JP2022038777A - Adhesive composition, cured product and adhesive sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive composition having excellent curability and pot life while maintaining good adhesiveness after heat curing.
SOLUTION: The pressure-sensitive adhesive composition is a cross-linking agent containing a cross-linking functional group, an acrylic polymer (a) having a glass transition temperature Tg of −70 to 0 ° C., and an aliphatic or alicyclic polyisocyanate. A blocked polyisocyanate containing the component (b1) and a secondary or tertiary alcohol (c), or derived from the acrylic polymer (a) and an aliphatic or alicyclic polyisocyanate and a blocking agent. The content of the monomer unit having a crosslinkable functional group is 0.1 to 20% by mass with respect to the total mass of the cross-linking agent component (b2) including the cross-linking agent component (b2), and the content of (b1) is contained. Is 0.05 to 20 parts by mass with respect to (a) 100 parts by mass, the content of (c) is 5 to 300 parts by mass with respect to (a) 100 parts by mass, and the content of (b2). Is (a) 0.1 to 20 parts by mass with respect to 100 parts by mass.
[Selection diagram] None

Description

The present invention relates to pressure-sensitive adhesive compositions, cured products and pressure-sensitive adhesive sheets.

Polyisocyanate is a polymer having a hydroxyl group or a carboxy group, and can be crosslinked at a temperature that is industrially easy to use from a relatively low temperature of room temperature or higher to about 150 ° C., has excellent adhesion to a substrate, etc., and is moderate at room temperature. Has a good pot life. Therefore, it is used for various purposes such as adhesives, adhesives, paints, and plastics. Among them, aromatic, alicyclic and aliphatic polyisocyanates are used for adhesive applications. However, when the polymer contained in the pressure-sensitive adhesive has a carboxy group and an alicyclic or aliphatic polyisocyanate is used as a cross-linking agent component, rapid thickening or gelation occurs in a short time of less than 1 hour. Therefore, there is a problem that it is difficult to use at the mass production level. There is also a problem that the viscosity is easily increased when the amount of crosslinked functional groups is large.

Patent Document 1 discloses a pressure-sensitive adhesive composition obtained by blending a polyfunctional isocyanate-based compound, a β-dicarbonyl compound, and an alcohol having 2 or more carbon atoms with a carboxy group-containing acrylic resin.

Japanese Unexamined Patent Publication No. 8-259922

However, the pressure-sensitive adhesive composition described in Patent Document 1 is complicated in that it is necessary to further add two kinds of compounds in addition to the cross-linking agent component composed of a polyfunctional isocyanate-based compound. Furthermore, when acetylacetone is blended as the β-dicarbonyl compound, the acetylacetone has acute toxicity and has a high boiling point of 140 ° C., so that it may remain in the cured product even after heating of the pressure-sensitive adhesive composition. be. Therefore, there is a demand for a pressure-sensitive adhesive composition that can suppress gelling and thickening, has a smaller number of components to be blended, and has a safer composition.

The present invention has been made in view of the above circumstances, and a pressure-sensitive adhesive composition having excellent curability and pot life while maintaining good adhesiveness after heat-curing, and the pressure-sensitive adhesive composition are used. A cured product and an adhesive sheet are provided.

That is, the present invention includes the following aspects.
(1) An acrylic polymer (a) having a crosslinkable functional group and having a glass transition temperature Tg of −70 ° C. or higher and 0 ° C. or lower.
Crosslinking agent component (b1) containing aliphatic or alicyclic polyisocyanate,
Containing secondary or tertiary alcohol (c),
Or, with the acrylic polymer (a)
Containing a cross-linking agent component (b2) containing an aliphatic or alicyclic polyisocyanate and a blocked polyisocyanate derived from a blocking agent,
The content of the monomer unit having a crosslinkable functional group with respect to the total mass of the acrylic polymer (a) is 0.1% by mass or more and 20% by mass or less.
The content of the cross-linking agent component (b1) is 0.05 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the acrylic polymer (a).
The content of the secondary or tertiary alcohol (c) is 5 parts by mass or more and 300 parts by mass or less with respect to 100 parts by mass of the acrylic polymer (a).
A pressure-sensitive adhesive composition in which the content of the cross-linking agent component (b2) is 0.1 part by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the acrylic polymer (a).
(2) The pressure-sensitive adhesive composition according to (1), wherein the aliphatic or alicyclic polyisocyanate has an average number of isocyanate functional groups of 2 or more.
(3) The pressure-sensitive adhesive composition according to (1) or (2), wherein the secondary or tertiary alcohol (c) contains a tertiary alcohol.
(4) The blocking agent is at least one compound selected from the group consisting of an active methylene compound, an oxime compound, an amine compound, a pyrazole compound, and a triazole compound, according to (1) to (3). The pressure-sensitive adhesive composition according to any one.
(5) The blocking agent is an active methylene compound, and the blocking agent is an active methylene compound.
The pressure-sensitive adhesive composition according to any one of (1) to (4), wherein the active methylene compound contains a malonic acid ester having a secondary alkyl group or a malonic acid ester having a tertiary alkyl group.
(6) The blocking agent is an active methylene compound, and the blocking agent is an active methylene compound.
The pressure-sensitive adhesive composition according to any one of (1) to (5), wherein the active methylene compound contains a malonic acid ester having a secondary alkyl group and a malonic acid ester having a tertiary alkyl group.
(7) Of (1) to (6), the weight average molecular weight Mw of the cross-linking agent component (b1) and the cross-linking agent component (b2) is 1.0 × 10 ³ or more and 1.0 × ¹⁰⁵ or less, respectively. The pressure-sensitive adhesive composition according to any one.
(8) The aliphatic or alicyclic polyisocyanate has at least one structure selected from the group consisting of a urethane structure, an allophanate structure, a biuret structure, a urea structure, and an isocyanurate structure (1) to (7). The pressure-sensitive adhesive composition according to any one of the above.
(9) Any one of (1) to (8), wherein the acrylic polymer (a) contains at least one acrylic acid ester unit having an alkyl group having 1 or more and 20 or less carbon atoms at the end of the ester group. The pressure-sensitive adhesive composition according to one.
(10) The pressure-sensitive adhesive composition according to any one of (1) to (9), wherein the crosslinkable functional group is one or more functional groups selected from the group consisting of a hydroxyl group, a carboxy group, and an epoxy group. thing.
(11) The pressure-sensitive adhesive according to any one of (1) to (10), wherein the acrylic polymer (a) has a weight average molecular weight Mw of 3.0 × 105 or more and ^2.5 × ¹⁰⁶ or less. Composition.
(12) A cured product obtained by curing the pressure-sensitive adhesive composition according to any one of (1) to (11) by heat or light.
(13) Substrate and
A pressure-sensitive adhesive layer is provided on the substrate.
A pressure-sensitive adhesive sheet in which the pressure-sensitive adhesive layer is made of a cured product of the pressure-sensitive adhesive composition according to any one of (1) to (11).
(14) The pressure-sensitive adhesive sheet according to (13), wherein the thickness of the pressure-sensitive adhesive layer is 0.1 μm or more and 1000 μm or less.
(15) A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer having a thickness of 45 μm, which is obtained by applying the pressure-sensitive adhesive composition on a polyethylene terephthalate film having a thickness of 38 μm and being dried and cured at 130 ° C. for 3 minutes, 23. After storage in a 50% RH environment for 7 days, the gel was immersed in ethyl acetate at 23 ° C. for 1 week and dried at 120 ° C. for 2 hours, and the gel content was 20% by mass or more and 98% by mass or less (13). ) Or the adhesive sheet according to (14).
(16) Adhesive having a width of 20 mm and a length of 100 mm, comprising a pressure-sensitive adhesive layer having a thickness of 45 μm, which is obtained by applying the pressure-sensitive adhesive composition on a polyethylene terephthalate film having a thickness of 25 μm, drying at 130 ° C. for 3 minutes, and curing the pressure-sensitive adhesive composition. After storing the sheet in a 23 ° C., 50% RH environment for 7 days, using a SUS304BA steel plate as an adherend, the sheet was pressure-bonded once with a 2 kg roller, cured at 23 ° C. for 30 minutes, and then 23 ° C., 300 mm / min. The pressure-sensitive adhesive sheet according to any one of (13) to (15), wherein the 180-degree peel adhesive strength measured at a speed is 0.05 N / 20 mm or more and 40 N / 20 mm or less.

According to the pressure-sensitive adhesive composition of the above aspect, it is possible to provide a pressure-sensitive adhesive composition having excellent curability and pot life while maintaining good adhesiveness after heat-curing.

Hereinafter, embodiments for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail. The present invention is not limited to the following embodiments. The present invention can be appropriately modified and carried out within the scope of the gist thereof.

In addition, in this specification, a "polyol" means a compound having two or more hydroxy groups (-OH).
As used herein, the term "polyisocyanate" means a reaction product in which a plurality of monomer compounds having one or more isocyanate groups (-NCO) are bonded.

As used herein, the term "constituent unit" means a structure derived from a single molecule of a monomer (monomer) in a structure constituting a polyisocyanate, a blocked polyisocyanate, or an acrylic polymer. For example, the monomer unit having a crosslinkable functional group indicates a structure caused by one molecule of the monomer having a crosslinkable functional group (monomer) in the acrylic polymer. The structural unit may be a unit directly formed by a (co) polymerization reaction of a monomer, or a unit in which a part of the unit is converted into another structure by treating the (co) polymer. There may be.

≪Adhesive composition≫
The pressure-sensitive adhesive composition of the present embodiment contains an acrylic polymer (a) having a crosslinkable functional group and having a glass transition temperature Tg of −70 ° C. or higher and 0 ° C. or lower.
Crosslinking agent component (b1) containing aliphatic or alicyclic polyisocyanate,
Containing secondary or tertiary alcohol (c),
Or, with the acrylic polymer (a)
It contains a cross-linking agent component (b2) containing an aliphatic or alicyclic polyisocyanate and a blocked polyisocyanate derived from a blocking agent.

That is, the pressure-sensitive adhesive composition of the present embodiment contains an acrylic polymer (a) having a crosslinkable functional group and having a glass transition temperature Tg of −70 ° C. or higher and 0 ° C. or lower.
Crosslinking agent component (b1) containing aliphatic or alicyclic polyisocyanate,
Includes secondary or tertiary alcohol (c).
Alternatively, the pressure-sensitive adhesive composition of the present embodiment contains an acrylic polymer (a) having a crosslinkable functional group and having a glass transition temperature Tg of −70 ° C. or higher and 0 ° C. or lower.
It contains a cross-linking agent component (b2) containing an aliphatic or alicyclic polyisocyanate and a blocked polyisocyanate derived from a blocking agent.

The content of the monomer unit having a crosslinkable functional group with respect to the total mass of the acrylic polymer (a) is 0.1% by mass or more and 20% by mass or less, and 0.1% by mass or more and 18% by mass or less. It is more preferably 0.1% by mass or more and 15% by mass or less, further preferably 0.1% by mass or more and 12% by mass or less, and particularly preferably 0.1% by mass or more and 10% by mass or less. When the content of the monomer unit having a crosslinkable functional group is within the above range, the adhesiveness after heat curing can be improved. For the content of the monomer unit having a crosslinkable functional group, for example, the ratio (percentage) of the mass of the monomer having a crosslinkable functional group to the total mass of all the monomers used in the synthesis is calculated. Obtained at. Alternatively, for example, it is calculated by combining the measurement of the acid value and the hydroxyl value of the acrylic polymer (a) with the measurement by infrared spectroscopy (IR) analysis method, nuclear magnetic resonance (NMR) analysis method or mass spectrometry method. can do.

When the pressure-sensitive adhesive composition of the present embodiment contains the cross-linking agent component (b1), the content of the cross-linking agent component (b1) is 0.05 part by mass or more with respect to 100 parts by mass of the acrylic polymer (a). It is 20 parts by mass or less, preferably 0.1 parts by mass or more and 15 parts by mass or less, more preferably 0.1 parts by mass or more and 10 parts by mass or less, and 0.1 parts by mass or more and 8 parts by mass or less. It is more preferably 0.2 parts by mass or more and 7 parts by mass or less. When the content of the cross-linking agent component (b1) is within the above range, the cohesive force and the adhesive force of the pressure-sensitive adhesive after heat curing can be improved. The content of the cross-linking agent component (b1) can be calculated from, for example, the blending amount of the acrylic polymer (a) and the cross-linking agent component (b1) at the time of producing the pressure-sensitive adhesive composition. Alternatively, the content of the cross-linking agent component (b1) can be measured by, for example, an IR analysis method, an NMR analysis method, or a mass spectrometry method.
Further, the content of the secondary or tertiary alcohol (c) is 5 parts by mass or more and 300 parts by mass or less, preferably 10 parts by mass or more and 250 parts by mass or less with respect to 100 parts by mass of the acrylic polymer (a). , 15 parts by mass or more and 250 parts by mass or less is more preferable, 20 parts by mass or more and 250 parts by mass or less is further preferable, 26 parts by mass or more and 250 parts by mass or less is further preferable, and 28 parts by mass or more and 250 parts by mass or less is further preferable. , 40 parts by mass or more and 200 parts by mass or less is particularly preferable, 45 parts by mass or more and 200 parts by mass or less is particularly preferable, and 50 parts by mass or more and 200 parts by mass or less is most preferable.
When the content of the secondary or tertiary alcohol (c) is at least the above lower limit value, it is possible to obtain a pressure-sensitive adhesive composition having excellent pot life while maintaining good adhesiveness after heat curing. On the other hand, when the content of the secondary or tertiary alcohol (c) is not more than the above upper limit value, a pressure-sensitive adhesive composition having a retained adhesive strength can be obtained. The content of the secondary or tertiary alcohol (c) can be calculated from, for example, the blending amount of the acrylic polymer (a) and the secondary or tertiary alcohol (c) at the time of producing the pressure-sensitive adhesive composition. Alternatively, the content of the secondary or tertiary alcohol (c) can be measured by, for example, an IR analysis method, an NMR analysis method, or a mass spectrometry method.

When the pressure-sensitive adhesive composition of the present embodiment contains the cross-linking agent component (b2), the content of the cross-linking agent component (b2) is 0.1 part by mass or more with respect to 100 parts by mass of the acrylic polymer (a). It is 20 parts by mass or less, preferably 0.1 parts by mass or more and 15 parts by mass or less, more preferably 0.1 parts by mass or more and 10 parts by mass or less, further preferably 0.1 parts by mass or more and 8 parts by mass or less, and 0. 1 part by mass or more and 5 parts by mass or less are particularly preferable, and 0.5 parts by mass or more and 4 parts by mass or less are most preferable. When the content of the cross-linking agent component (b2) is at least the above lower limit value, the cohesive force and the adhesive force can be excellent, while when it is at least the above upper limit value, the adhesive force after heat curing and the adhesive force can be improved. You can keep the pot life good. The content of the cross-linking agent component (b2) can be calculated from, for example, the blending amount of the acrylic polymer (a) and the cross-linking agent component (b2) at the time of producing the pressure-sensitive adhesive composition. Alternatively, the content of the cross-linking agent component (b2) can be measured by, for example, an IR analysis method, an NMR analysis method, or a mass spectrometry method.

By having the above-mentioned structure, the pressure-sensitive adhesive composition of the present embodiment is excellent in curability and pot life while maintaining good stickiness and cohesive force after heat-curing.
Next, each component contained in the pressure-sensitive adhesive composition of the present embodiment will be described in detail below.

<Acrylic polymer (a)>
The acrylic polymer (a) has a crosslinkable functional group and has a glass transition temperature Tg of −70 ° C. or higher and 0 ° C. or lower.
The acrylic polymer (a) contains one or more polymerizable acrylic monomer units having a crosslinkable functional group and one or more polymerizable acrylic monomer units having no crosslinkable functional group, and copolymerizes these monomers. Obtained by letting it.

Examples of the crosslinkable functional group capable of cross-linking with the cross-linking agent component (b) include a hydroxyl group, a carboxy group, an epoxy group and the like, and among them, a hydroxyl group is preferable.
The acrylic polymer (a) may contain one type of crosslinkable functional group alone, or may contain two or more types of different types of crosslinkable functional groups in combination. That is, the acrylic polymer (a) may be obtained by polymerizing one type of polymerizable monomer having one or more crosslinkable functional groups in one molecule alone, and different types of crosslinkable functional groups. It may be obtained by combining two or more kinds of polymerizable monomers having the above and copolymerizing them.

Examples of the polymerizable monomer having one or more crosslinkable functional groups in one molecule include those shown in the following (i) to (v). These may be used alone or in combination of two or more.
(I) Acrylic acid ester having a hydroxyl group such as -2-hydroxyethyl acrylate, -2-hydroxypropyl acrylate, -2-hydroxybutyl acrylate, -4-hydroxybutyl acrylate, -6-hydroxyhexyl acrylate, etc. Kind.
(Ii) Methacrylic acid ester having a hydroxyl group such as -2-hydroxyethyl methacrylate, -2-hydroxypropyl methacrylate, -2-hydroxybutyl methacrylate, -4-hydroxybutyl methacrylate, -6-hydroxyhexyl methacrylate and the like. Kind.
(Iii) (meth) acrylic acid esters having a polyvalent hydroxy group such as acrylic acid monoester or methacrylic acid monoester of glycerin, acrylic acid monoester or methacrylic acid monoester of trimethylolpropane.
(Iv) Unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, and itaconic acid.
(V) A polymerizable monomer having an epoxy group such as glycidyl methacrylate, 1,2-epoxy-4-vinylcyclohexane, allyl glycidyl ether, and 4-hydroxybutyl acrylate glycidyl ether.

Examples of other monomers copolymerizable with the polymerizable monomer include those shown in the following (i) to (iii). These may be used alone or in combination of two or more.
(I) Methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, -n-butyl (meth) acrylate, isobutyl (meth) acrylate, (meth) ) Acrylic acid-sec-butyl, (meth) acrylate-tert-butyl, (meth) acrylate pentyl, (meth) acrylate isopentyl, (meth) acrylate hexyl, (meth) acrylate -2-ethylhexyl, (Meta) heptyl acrylate, (meth) octyl acrylate, (meth) isooctyl acrylate, (meth) nonyl acrylate, (meth) isononyl acrylate, (meth) decyl acrylate, (meth) isodecyl acrylate, ( Undecyl acrylate, (meth) dodecyl acrylate ((meth) lauryl acrylate), (meth) tridecyl acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, (meth) Heptadecyl acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, nonadecil (meth) acrylate, eicocil (meth) acrylate, benzyl (meth) acrylate, cyclohexyl (meth) acrylate, etc. (Meta) Acrylic acid esters.
(Ii) Unsaturated amides such as (meth) acrylamide, N-methylol acrylamide, diacetone acrylamide, and dimethylaminopropyl acrylamide.
(Iii) Styrene, vinyltoluene, vinyl acetate, (meth) acrylonitrile, N-vinylpyrrolidone, N-vinylcaprolactam, acryloylmorpholine, (meth) dimethylaminoethyl acrylate, (meth) diethylaminoethyl acrylate.

Further, as other monomers copolymerizable with the polymerizable monomer, the polymerizable ultraviolet stables disclosed in Reference 1 (Japanese Patent Laid-Open No. 1-261409) and Reference 2 (Japanese Patent Laid-Open No. 3-006273) and the like. A sex monomer may be used.
Specifically, as the polymerizable ultraviolet-stable monomer, for example, 4- (meth) acryloyloxy-2, 2,6,6-tetramethylpiperidine, 4- (meth) acryloylamino-2, 2,6 , 6-Tetramethylpiperidine, 1-crotonoyl-4-crotonoyloxy-2, 2,6,6-tetramethylpiperidine, 2-hydroxy-4- (3-methacryloxy-2-hydroxypropoxy) benzophenone and the like. Be done.

Above all, the acrylic polymer (a) preferably contains one or more acrylic acid ester units having an alkyl group having 1 or more and 20 or less carbon atoms at the end of the ester group.
The acrylic acid ester unit having an alkyl group having 1 or more and 20 or less carbon atoms at the terminal of the ester group may or may not contain a crosslinkable functional group.
The alkyl group of the acrylic acid ester unit containing a crosslinkable functional group has 1 or more and 20 or less carbon atoms, preferably 1 or more and 18 or less, and more preferably 2 or more and 18 or less.
On the other hand, the number of carbon atoms of the alkyl group of the acrylic acid ester unit containing no crosslinkable functional group is 1 or more and 20 or less, preferably 1 or more and 18 or less, more preferably 2 or more and 18 or less, and 4 or more and 18 or less. More preferred.

For example, the above monomer component is solution-polymerized in the presence of a known radical polymerization initiator such as a peroxide or an azo compound, and if necessary, diluted with an organic solvent or the like to obtain an acrylic polymer (a). ) Can be obtained.

When the water-based acrylic polymer (a) is obtained, it can be produced by a known method such as a method of solution-polymerizing an olefinically unsaturated compound to convert it into an aqueous layer or an emulsion polymerization. In that case, water solubility or water dispersibility can be imparted by neutralizing an acidic moiety such as a carboxylic acid-containing monomer such as acrylic acid or methacrylic acid or a sulfonic acid-containing monomer with an amine or ammonia.

[Glass transition temperature of acrylic polymer (a)]
The glass transition temperature Tg of the acrylic polymer (a) is −70 ° C. or higher and 0 ° C. or lower, preferably −70 ° C. or higher and −5 ° C. or lower, more preferably −70 ° C. or higher and −10 ° C. or lower, and −70 ° C. or higher and −. It is more preferably 15 ° C. or lower. When the glass transition temperature Tg of the acrylic polymer (a) is within the above range, the adhesive strength and cohesive strength of the cured product of the pressure-sensitive adhesive composition tend to be more excellent. The glass transition temperature of the acrylic polymer (a) is, for example, a differential scanning calorimetry (DSC) measuring device obtained by removing the organic solvent and water in the acrylic polymer (a) solution under reduced pressure and then vacuum-drying the mixture. The value measured under the condition of a heating rate of 5 ° C./min can be used as the glass transition temperature.

[Weight average molecular weight of acrylic polymer (a)]
The weight average molecular weight Mw of the acrylic polymer (a) is preferably 3.0 × 10 ⁵ or more and 2.5 × ¹⁰⁶ or less, and 4.0 × 10 ⁵ or more and 2.0 × 10 ⁶ or less. Is more preferable, and 4.5 × 105 or more and 1.8 × ¹⁰⁶ is more preferable, and 4.5 × ^{10 5} or more and 1.7 × ¹⁰⁶ or less is particularly preferable. When the weight average molecular weight of the acrylic polymer (a) is within the above range, the adhesive strength, cohesive strength, and durability of the cured product of the pressure-sensitive adhesive composition tend to be more excellent. The weight average molecular weight Mw of the acrylic polymer (a) can be measured, for example, by using the method described in Examples described later.

<Crosslinking agent component (b)>
The pressure-sensitive adhesive composition of the present embodiment contains a cross-linking agent component (b1) containing a polyisocyanate or a cross-linking agent component (b2) containing a blocked polyisocyanate as the cross-linking agent component (b).

[Crosslinking agent component (b1)]
The polyisocyanate contained in the cross-linking agent component (b1) is a reaction obtained by reacting a plurality of monomer compounds having one or more isocyanate groups (-NCO) (hereinafter, may be referred to as "isocyanate monomer"). It is a thing. The isocyanate monomer used for producing the polyisocyanate is one or more kinds of diisocyanates selected from the group consisting of aliphatic diisocyanates and alicyclic diisocyanates.
The diisocyanate preferably has 4 or more and 30 or less carbon atoms. Specific examples of the diisocyanate include the following. These diisocyanates may be used alone or in combination of two or more.
(1) 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate (hereinafter, may be referred to as "HDI"), 2,2,4-trimethyl-1,6-diisocyanatohexane, 2, Aliphatic diisocyanates such as 4,4-trimethyl-1,6-hexamethylene diisocyanate, 2-methylpentane-1,5-diisocyanate (MPDI), and lysine diisocyanate (hereinafter, may be referred to as "LDI").
(2) Fats such as isophorone diisocyanate (hereinafter sometimes referred to as "IPDI"), 1,3-bis (diisocyanatemethyl) cyclohexane, 4,4'-dicyclohexylmethane diisocyanate, diisocyanate norbornane, di (isocyanatemethyl) norbornane, etc. Cyclic diisocyanate.

Further, the isocyanate monomer is more preferably HDI or IPDI because of its easy industrial availability. Further, the isocyanate monomer is more preferably HDI from the viewpoint of reducing the viscosity of the cross-linking agent component.

Further, as the isocyanate monomer used for producing the polyisocyanate, either an aliphatic diisocyanate or an alicyclic diisocyanate may be used alone, or a combination thereof may be used, but the aliphatic diisocyanate and the alicyclic diisocyanate may be used. It is preferable to use a combination of group diisocyanates, and it is particularly preferable to use HDI and IPDI. By using the aliphatic diisocyanate and the alicyclic diisocyanate, the elastic modulus and the cohesive force of the pressure-sensitive adhesive can be improved.

In polyisocyanate, from the viewpoint of improving the elastic modulus and cohesive force of the pressure-sensitive adhesive, the mass ratio of the structural unit derived from the aliphatic diisocyanate to the structural unit derived from the alicyclic diisocyanate (the structural unit derived from the aliphatic diisocyanate / the alicyclic). The constituent unit derived from the group diisocyanate) is preferably 50/50 or more and 95/5 or less, more preferably 55/45 or more and 93/7 or less, further preferably 60/40 or more and 91/9 or less, and 65/35 or more and 90. It is more preferably / 10 or less.
When the mass ratio of the constituent unit derived from the aliphatic diisocyanate to the constituent unit derived from the alicyclic diisocyanate is at least the above lower limit value, it is possible to more effectively suppress the elongation and the decrease in flexibility of the adhesive. Can be done. On the other hand, when it is not more than the above upper limit value, the elastic modulus and the cohesive force of the pressure-sensitive adhesive can be further improved.
The mass ratio of the structural unit derived from the aliphatic diisocyanate to the structural unit derived from the alicyclic diisocyanate can be calculated by using, for example, the following method. First, the mass of unreacted aliphatic diisocyanate and the unreacted alicyclic diisocyanate are obtained from the mass of unreacted diisocyanate after the reaction and the concentration of aliphatic diisocyanate and the concentration of alicyclic diisocyanate in the unreacted diisocyanate obtained by gas chromatograph measurement. Calculate the mass of. Then, after subtracting the mass of the unreacted aliphatic diisocyanate and the mass of the unreacted aliphatic diisocyanate calculated above from the mass of the charged aliphatic diisocyanate and the mass of the alicyclic diisocyanate, the obtained difference is the fat, respectively. The mass of the constituent unit derived from the group diisocyanate and the mass of the constituent unit derived from the alicyclic diisocyanate. Then, by dividing the mass of the constituent unit derived from the aliphatic diisocyanate by the mass of the constituent unit derived from the alicyclic diisocyanate, the mass of the constituent unit derived from the aliphatic diisocyanate with respect to the constituent unit derived from the alicyclic diisocyanate. The ratio is obtained.

As the isocyanate monomer used for producing the polyisocyanate, an isocyanate monomer as shown below may be further used.
(1) Aromatic diisocyanates such as diphenylmethane-4,4'-diisocyanate (MDI), 1,5-naphthalenediocyanate, tolylene diisocyanate (TDI), xylylene diisocyanate, m-tetramethylxylylene diisocyanate (TMXDI).
(2) 4-Isocyanate Methyl-1,8-octamethylene diisocyanate (hereinafter, may be referred to as "NTI"), 1,3,6-hexamethylene triisocyanate (hereinafter, may be referred to as "HTI"). , Bis (2-isocyanatoethyl) 2-isocyanatoglutarate (hereinafter, may be referred to as "GTI"), lysine triisocyanate (hereinafter, may be referred to as "LTI") and the like.

(Polyol)
The polyisocyanate is preferably derived from the above-mentioned diisocyanate and a polyol having an average number of hydroxyl group functional groups of 2.0 or more and 8.0 or less. Thereby, the average number of isocyanate groups of the obtained polyisocyanate can be further increased. In the polyisocyanate, a urethane group is formed by the reaction between the hydroxyl group of the polyol and the isocyanate group of the diisocyanate.

The average number of hydroxyl group functional groups of the polyol is preferably 2.0 or more and 8.0 or less, more preferably 2 or more and 6 or less, and further preferably 2 or more and 5 or less. The average number of hydroxyl group functional groups of the polyol here is the number of hydroxyl groups existing in one molecule of the polyol.

From the viewpoint of the flexibility of the pressure-sensitive adhesive, the number average molecular weight of the polyol is preferably 50 or more and 5000 or less, preferably 100 or more and 4500 or less, more preferably 130 or more and 4300 or less, and further preferably 200 or more and 4200 or less.
When the number average molecular weight of the polyol is within the above range, the pressure-sensitive adhesive composition containing the cross-linking agent component (b1) is superior in adhesive strength, cohesive strength, and flexibility. The number average molecular weight Mn of the polyol is, for example, a polystyrene-based number average molecular weight measured by gel permeation chromatography (GPC).

Examples of such polyols include trimethylolpropane, glycerol, polycaprolactone polyols derived from trihydric or higher polyhydric alcohols and ε-caprolactone.
Commercially available polycaprolactone polyols include, for example, Daicel's "Plaxel 303" (number average molecular weight 300), "Plaxel 305" (number average molecular weight 550), "Plaxel 308" (number average molecular weight 850), and "Plaxel 309". "(Number average molecular weight 900)," Pluxel 312 "(Number average molecular weight 1250)," Pluxel 320 "(Number average molecular weight 2000)," Pluxel 205 "(Number average molecular weight 530)" Pluxel 210 "(Number average molecular weight 1000) , "Plaxel 220" (number average molecular weight 2000), "Plaxel 230" (number average molecular weight 3000), "Plaxel 240" (number average molecular weight 4000) and the like.

The polyisocyanate can have at least one structure selected from the group consisting of an allophanate structure, a uretdione structure, an iminooxadiazinedione structure, an isocyanurate structure, a urea structure, a urethane structure, and a biuret structure. Above all, it is preferable to have at least one structure selected from the group consisting of a urethane structure, an allophanate structure, a biuret structure, a urea structure, and an isocyanurate group.

(Manufacturing method of polyisocyanate)
The method for producing polyisocyanate will be described in detail below.
The polyisocyanate is, for example, an allophanate-forming reaction forming an allophanate structure, a uretdione-forming reaction forming a uretdione structure, an iminooxadiazine-dione formation reaction forming an iminooxadiazinedione structure, and an isocyanurate-forming reaction forming an isocyanurate structure. The reaction, the urea (urea) conversion reaction that forms the urea structure, the urethane conversion reaction that forms the urethane structure, and the biuret conversion reaction that forms the biuret structure are all produced at once in the presence of excess isocyanate monomer, and the reaction is completed. Later, it can be obtained by removing the unreacted isocyanate monomer. That is, the polyisocyanate obtained by the above reaction is a product in which a plurality of the above-mentioned isocyanate monomers are bonded, and has an allophanate structure, a uretdione structure, an iminooxadiazinedione structure, an isocyanurate structure, a urea structure, a urethane structure, and a biuret. It is a reactant having one or more kinds selected from the group consisting of structures.
Further, the above reactions may be carried out separately, and the obtained polyisocyanates may be mixed at a specific ratio.
From the viewpoint of simplicity of production, it is preferable to carry out the above reaction at once to obtain a polyisocyanate, and from the viewpoint of freely adjusting the molar ratio of each functional group, it is preferable to separately produce and then mix.

(1) Method for Producing Alofanate Structure-Containing Polyisocyanate The allophanate structure-containing polyisocyanate can be obtained by adding an alcohol to an isocyanate monomer and using an allophanate reaction catalyst.
The alcohol used to form the allophanate structure is preferably an alcohol formed only of carbon, hydrogen and oxygen.
Specific examples of the alcohol include, but are not limited to, monoalcohol, dialcohol and the like. These alcohols may be used alone or in combination of two or more.
Examples of the monoalcohol include methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol and the like.
Examples of the dialcohol include ethylene glycol, 1,3-butanediol, neopentyl glycol, 2-ethylhexanediol and the like.
Among them, as the alcohol, monoalcohol is preferable, and monoalcohol having a molecular weight of 200 or less is more preferable.

Examples of the allophanate formation reaction catalyst include, but are not limited to, alkyl carboxylates such as tin, lead, zinc, bismuth, zirconium, and zirconyl.
Examples of the tin alkylcarboxylic acid salt (organic tin compound) include tin 2-ethylhexanoate and dibutyltin dilaurate.
Examples of the lead alkylcarboxylic acid salt (organolead compound) include lead 2-ethylhexanoate.
Examples of the alkylcarboxylate (organozinc compound) of zinc include zinc 2-ethylhexanoate and the like.
Examples of the alkylcarboxylate of bismuth include bismuth 2-ethylhexanoate.
Examples of the alkylcarboxylate of zirconium include zirconium 2-ethylhexanoate.
Examples of the alkylcarboxylate of zirconyl include zirconyl 2-ethylhexanoate. These catalysts may be used alone or in combination of two or more.
Further, the isocyanurate-forming reaction catalyst described later can also be an allophanate-forming reaction catalyst. When an allophanate reaction is carried out using an isocyanurate-forming reaction catalyst described later, an isocyanurate group-containing polyisocyanate (hereinafter, may be referred to as "isocyanurate-type polyisocyanate") is naturally produced.
Above all, it is economically preferable to carry out the allophanate formation reaction and the isocyanurate formation reaction using an isocyanurate formation reaction catalyst described later as the allophanate formation reaction catalyst.

The lower limit of the amount of the allophanation reaction catalyst used is preferably 10 mass ppm, more preferably 20 mass ppm, and 40 mass ppm with respect to the mass of the charged isocyanate monomer. It is more preferably 80 mass ppm, and particularly preferably 80 mass ppm.
The upper limit of the amount of the allophanation reaction catalyst used is preferably 1000 mass ppm, more preferably 800 mass ppm, and 600 mass ppm with respect to the mass of the charged isocyanate monomer. It is more preferably 500 mass ppm, and particularly preferably 500 mass ppm.
That is, the amount of the above-mentioned allophanate reaction catalyst used is preferably 10% by mass or more and 1000% by mass or less, and more preferably 20% by mass or more and 800% by mass or less with respect to the mass of the charged isocyanate monomer. It is more preferably 40% by mass or more and 600% by mass or less, and particularly preferably 80% by mass or more and 500% by mass or less.

The lower limit of the allophanate reaction temperature is preferably 40 ° C, more preferably 60 ° C, further preferably 80 ° C, and particularly preferably 100 ° C.
The upper limit of the allophanate reaction temperature is preferably 180 ° C, more preferably 160 ° C, and even more preferably 140 ° C.
That is, the allophanate reaction temperature is preferably 40 ° C. or higher and 180 ° C. or lower, more preferably 60 ° C. or higher and 160 ° C. or lower, further preferably 80 ° C. or higher and 140 ° C. or lower, and 100 ° C. or higher. It is particularly preferable that the temperature is 140 ° C. or lower.
When the allophanate reaction temperature is equal to or higher than the above lower limit, the reaction rate can be further improved. When the allophanate reaction temperature is not more than the above upper limit value, coloring of polyisocyanate and the like can be more effectively suppressed.

(2) Method for producing polyisocyanate containing uretdione structure When deriving a polyisocyanate having a uretdione structure from an isocyanate monomer, for example, the isocyanate monomer is increased in quantity by using a uretdione reaction catalyst or by heat. Can be manufactured.
The uretdione reaction catalyst is not particularly limited, and examples thereof include trialkylphosphine, tris (dialkylamino) phosphine, third phosphine such as cycloalkylphosphine, and Lewis acid.
Examples of the trialkylphosphine include tri-n-butylphosphine and tri-n-octylphosphine.
Examples of the tris (dialkylamino) phosphine include tris- (dimethylamino) phosphine.
Examples of the cycloalkylphosphine include cyclohexyl-di-n-hexylphosphine.
Examples of Lewis acid include boron trifluoride and zinc hydrochloride.

Many uretdioneization reaction catalysts can also promote isocyanurate-forming reactions at the same time.
When a uretdioneization reaction catalyst is used, a deactivating agent for the uretdioneization reaction catalyst such as phosphoric acid and methyl paratoluenesulfonate may be added to stop the uretdioneization reaction when the desired yield is obtained. preferable.
Further, when one or more diisocyanates selected from the group consisting of the aliphatic diisocyanate and the alicyclic diisocyanate are heated without using a uretdione reaction catalyst to obtain a polyisocyanate having a uretdione group, the heating temperature thereof is set. , 120 ° C. or higher is preferable, and 150 ° C. or higher and 170 ° C. or lower is more preferable. The heating time is preferably 1 hour or more and 4 hours or less.

(3) Method for producing iminooxadiazinedione structure-containing polyisocyanate When the iminooxadiazinedione structure-containing polyisocyanate is derived from an isocyanate monomer, an iminooxadiazinedione formation reaction catalyst is usually used.
Examples of the iminooxadiazine diionization catalyst include those shown in 1) or 2) below.
1) (Poly) hydrogen fluoride represented by the general formula M [F _n ] or the general formula M [F _n (HF) _m ] (in the formula, m and n have a relationship of m / n> 0. It is an integer to be satisfied. M is an n-charged cation (mixture) or one or more radicals having a total n-valence.)
2) A compound represented by the general formula R ¹ -CR'2 _- C (O) O- or general formula R ² = CR'-C (O) O-, and a quaternary ammonium cation or a quaternary ammonium cation. A compound consisting of a quaternary phosphonium cation.
(In the formula, R ¹ and R ² are independently linear, branched or cyclic, saturated or unsaturated perfluoroalkyl groups having 1 or more and 30 or less carbon atoms. A plurality of R'are each. It is an alkyl group or an aryl group having 1 to 20 carbon atoms which may independently contain a hydrogen atom or a hetero atom.)

Specific examples of the compound ((poly) hydrogen fluoride) of 1) include tetramethylammonium fluoride hydrate and tetraethylammonium fluoride.
Specifically, as the compound of 2), for example, 3,3,3-trifluorocarboxylic acid, 4,4,4,3,3-pentafluorobutanoic acid, 5,5,5,4,4,3 Examples thereof include 3-heptafluoropentanoic acid and 3,3-difluoropropa-2-enoic acid.
Among them, as the iminooxadiazine diionization reaction catalyst, 1) is preferable from the viewpoint of availability, and 2) is preferable from the viewpoint of safety.

The lower limit of the amount of the iminooxadiazine diionization catalyst used is not particularly limited, but from the viewpoint of reactivity, the mass ratio is preferably 5 ppm and more preferably 10 ppm with respect to the isocyanate monomer such as HDI as a raw material. , 20 ppm is more preferable.
The upper limit of the amount of the iminooxadiazine diionization catalyst used is preferably 5000 ppm by mass ratio with respect to the isocyanate monomer such as HDI, which is a raw material, from the viewpoint of suppressing coloration and discoloration of the product and controlling the reaction. 2000 ppm is more preferable, and 500 ppm is even more preferable.
That is, the amount of the iminooxadiazine diionization catalyst used is preferably 5 ppm or more and 5000 ppm or less, more preferably 10 ppm or more and 2000 ppm or less, and 20 ppm or more in terms of mass ratio with respect to the isocyanate monomer such as HDI as a raw material. More preferably, it is 500 ppm or less.

The lower limit of the reaction temperature for iminooxadiazinedione formation is not particularly limited, but is preferably 40 ° C, more preferably 50 ° C, and even more preferably 60 ° C from the viewpoint of reaction rate.
The upper limit of the reaction temperature for iminooxadiazine dioneization is preferably 150 ° C., more preferably 120 ° C., and even more preferably 110 ° C. from the viewpoint of suppressing coloration and discoloration of the product.
That is, the reaction temperature for iminooxadiazine dioneization is preferably 40 ° C. or higher and 150 ° C. or lower, more preferably 50 ° C. or higher and 120 ° C. or lower, and even more preferably 60 ° C. or higher and 110 ° C. or lower.

When the iminooxadiazinedioneization reaction reaches the desired iminooxadiazinedione group content, the iminooxadiazinedioneization reaction can be stopped. The iminooxadiazine diionization reaction can be stopped, for example, by adding an acidic compound to the reaction solution. Examples of the acidic compound include phosphoric acid, acidic phosphoric acid ester, sulfuric acid, hydrochloric acid, sulfonic acid compound and the like. This neutralizes the iminooxadiazine diionization reaction catalyst, or inactivates it by thermal decomposition, chemical decomposition, or the like. After stopping the reaction, if necessary, perform filtration.

(4) Method for Producing Isocyanurate Structure-Containing Polyisocyanate As a catalyst for deriving a polyisocyanate-containing polyisocyanate from an isocyanate monomer, a commonly used isocyanurate-forming reaction catalyst can be mentioned.

The isocyanurate-forming reaction catalyst is not particularly limited, but is generally preferably one having basicity. Specific examples of the isocyanurate-forming reaction catalyst include those shown below.
1) Hydroxide of tetraalkylammonium such as tetramethylammonium, tetraethylammonium, tetrabutylammonium, and acetate, propionate, octylate, capricate, myristate, and benzoate of the tetraalkylammonium. Organic weak salts such as.
2) Hydroxide of aryltrialkylammonium such as benzyltrimethylammonium and trimethylphenylammonium, acetate of the aryltrialkylammonate, propionate, octylate, capricate, myristate, benzoate and the like. Organic weak acid salt.
3) Hydroxide of hydroxyalkylammonium such as trimethylhydroxyethylammonium, trimethylhydroxypropylammonium, triethylhydroxyethylammonium, triethylhydroxypropylammonium, and acetate, propionate, octylate, capric acid of the hydroxyalkylammonium. Organic weak salts such as salts, myristates and benzoates.
4) Metal salts of alkylcarboxylic acids such as acetic acid, propionic acid, caproic acid, octyl acid, caproic acid and myristic acid such as tin, zinc and lead.
5) Metallic alcoholates such as sodium and potassium.
6) Aminosilyl group-containing compound such as hexamethylene disilazane.
7) Mannich bases.
8) A mixture of tertiary amines and an epoxy compound.
9) Phosphorus compounds such as tributylphosphine.

Above all, from the viewpoint of less likely to generate unnecessary by-products, the quaternary ammonium hydrooxide or the quaternary ammonium organic weak acid salt is preferable as the isocyanurate-forming reaction catalyst, and the tetraalkylammonium hydroxide. More preferably, it is an organic weakened salt of tetraalkylammonium, a hydroxide of aryltrialkylammonium, or an organic weakened salt of aryltrialkylammonium.

The upper limit of the amount of the isocyanurate-forming reaction catalyst used is preferably 1000 mass ppm, more preferably 500 mass ppm, and 100 mass ppm with respect to the mass of the charged isocyanate monomer. Is more preferable.
On the other hand, the lower limit of the amount of the above-mentioned isocyanurate-forming reaction catalyst used is not particularly limited, but may be, for example, 10 mass ppm.

The isocyanurate-forming reaction temperature is preferably 50 ° C. or higher and 120 ° C. or lower, and more preferably 60 ° C. or higher and 90 ° C. or lower. When the isocyanurate-forming reaction temperature is not more than the above upper limit value, coloring of polyisocyanate and the like tend to be more effectively suppressed.

When the desired conversion rate (the ratio of the mass of the polyisocyanate produced in the isocyanurate-forming reaction to the mass of the charged isocyanate monomer) is reached, the isocyanurate-forming reaction is carried out with an acidic compound (for example, phosphoric acid, acidic phosphoric acid). It is stopped by the addition of (ester, etc.).
In order to obtain polyisocyanate, it is necessary to stop the progress of the reaction at an early stage. However, since the initial reaction rate of the isocyanurate-forming reaction is very fast, it is difficult to stop the progress of the reaction at the initial stage, and it is necessary to carefully select the reaction conditions, especially the addition amount and method of the catalyst. be. For example, a method of dividing and adding the catalyst at regular time intervals is recommended as a suitable method.
Therefore, the conversion rate of the isocyanurate-forming reaction for obtaining a polyisocyanate is preferably 10% or more and 60% or less, more preferably 15% or more and 55% or less, and 20% or more and 50% or less. Is even more preferred.
When the conversion rate of the isocyanurate-forming reaction is not more than the above upper limit value, the blocked polyisocyanate component can have a lower viscosity. Further, when the conversion rate of the isocyanurate-forming reaction is at least the above lower limit value, the reaction stop operation can be performed more easily.

Further, when inducing a polyisocyanate containing an isocyanurate group, an alcohol having a valence of 1 or more and a valence of 6 or less can be used in addition to the isocyanate monomer.
Examples of alcohols having a valence of 1 or more and 6 or less that can be used include non-polymerizable alcohols and polymerizable alcohols. The term "non-polymerizable alcohol" as used herein means an alcohol having no polymerizable group. On the other hand, the "polymerizable alcohol" means an alcohol obtained by polymerizing a monomer having a polymerizable group and a hydroxyl group.
Examples of the non-polymerizable alcohol include polyhydric alcohols such as monoalcohols, diols, triols and tetraols.
Examples of monoalcohols include methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, n-pentanol, n-hexanol, n-octanol, n-nonanol, and 2-ethylbutanol. , 2,2-Dimethylhexanol, 2-ethylhexanol, cyclohexanol, methylcyclohexanol, ethylcyclohexanol and the like.
Examples of diols include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, and 1, 3-butanediol, 1,4-butanediol, 2,3-butanediol, 2-methyl-1,2-propanediol, 1,5-pentanediol, 2-methyl-2,3-butanediol, 1, 6-hexanediol, 1,2-hexanediol, 2,5-hexanediol, 2-methyl-2,4-pentanediol, 2,3-dimethyl-2,3-butanediol, 2-ethyl-hexanediol, 1,2-octanediol, 1,2-decanediol, 2,2,4-trimethylpentanediol, 2-butyl-2-ethyl-1,3-propanediol, 2,2-diethyl-1,3-propane Examples include diol.
Examples of triols include glycerin, trimethylolpropane and the like.
Examples of the tetraols include pentaerythritol and the like.

The polymerizable alcohol is not particularly limited, and examples thereof include polyester polyols, polyether polyols, acrylic polyols, and polyolefin polyols.

The polyester polyols are not particularly limited, and examples thereof include products obtained by a condensation reaction between a dibasic acid alone or a mixture and a polyhydric alcohol alone or a mixture.
The dibasic acid is not particularly limited, but is at least one selected from the group consisting of carboxylic acids such as succinic acid, adipic acid, sebacic acid, dimer acid, maleic anhydride, phthalic acid anhydride, isophthalic acid, and terephthalic acid. Species dibasic acid can be mentioned.
The polyhydric alcohol is not particularly limited, and examples thereof include at least one polyhydric alcohol selected from the group consisting of ethylene glycol, propylene glycol, diethylene glycol, neopentyl glycol, trimethylolpropane, and glycerin.
Examples of polyester polyols include polycaprolactones obtained by ring-opening polymerization of ε-caprolactone using the above polyhydric alcohol.

The polyether polyols are not particularly limited, but for example, an alkali metal hydroxide or a strongly basic catalyst is used to add an alkylene oxide alone or a mixture to a polyhydric alcohol alone or a mixture. Examples thereof include polyether polyols obtained by reacting a polyamine compound with an alkylene oxide, and so-called polymer polyols obtained by polymerizing acrylamide or the like using the above-mentioned polyethers as a medium.
Examples of the alkali metal include lithium, sodium, potassium and the like.
Examples of the strongly basic catalyst include alcoholates, alkylamines and the like.
Examples of the polyhydric alcohol include those similar to those exemplified in the above polyester polyols.
Examples of the alkylene oxide include ethylene oxide, propylene oxide, butylene oxide, cyclohexene oxide, styrene oxide and the like.
Examples of the polyamine compound include ethylenediamines.

The acrylic polyols are not particularly limited, but for example, an ethylenically unsaturated bond-containing monomer having a hydroxyl group alone or a mixture thereof and another ethylenically unsaturated bond-containing monomer copolymerizable therewith are used alone. Alternatively, a copolymer of a mixture may be used.
The ethylenically unsaturated bond-containing monomer having a hydroxyl group is not particularly limited, and for example, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxy methacrylate. Examples include butyl.
The other ethylenically unsaturated bond-containing monomer copolymerizable with the ethylenically unsaturated bond-containing monomer having a hydroxyl group is not particularly limited, and is, for example, an acrylic acid ester, a methacrylic acid ester, or an unsaturated carboxylic acid. , Unsaturated amides, vinyl monomers, vinyl monomers having a hydrolyzable silyl group.
Examples of the acrylic acid ester include methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, -n-butyl acrylate, isobutyl acrylate, -n-hexyl acrylate, cyclohexyl acrylate, and -2 acrylate. -Ethylhexyl, lauryl acrylate, benzyl acrylate, phenyl acrylate and the like can be mentioned.
Examples of the methacrylic acid ester include methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, -n-butyl methacrylate, isobutyl methacrylate, -n-hexyl methacrylate, cyclohexyl methacrylate, and -2 methacrylic acid. -Ethylhexyl, lauryl methacrylate, benzyl methacrylate, phenyl methacrylate and the like can be mentioned.
Examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic acid, itaconic acid and the like.
Examples of unsaturated amides include acrylamide, methacrylamide, N, N-methylenebisacrylamide, diacetoneacrylamide, diacetonemethacrylamide, maleic acid amide, maleimide and the like.
Examples of the vinyl-based monomer include glycidyl methacrylate, styrene, vinyltoluene, vinyl acetate, acrylonitrile, dibutyl fumarate and the like.
Examples of the vinyl-based monomer having a hydrolyzable silyl group include vinyltrimethoxysilane, vinylmethyldimethoxysilane, γ- (meth) acryloxypropyltrimethoxysilane, and the like.

Examples of the polyolefin polyols include hydroxyl-terminated polybutadiene and hydrogenated products thereof.

(5) Method for Producing Polyisocyanate Containing Urea Structure When deriving a polyisocyanate containing a urea structure from an isocyanate monomer, for example, it is necessary to mix an excess isocyanate monomer with water or a primary or secondary amine. It can be produced by adding a urea conversion reaction catalyst according to the above.
The polyisocyanate containing a urea structure can be obtained, for example, by stirring at a temperature of 23 ° C. or higher for 30 minutes or longer (preferably 60 minutes or longer).

(6) Method for Producing Polyisocyanate Containing Urethane Structure When deriving a polyisocyanate containing a urethane structure from an isocyanate monomer, for example, an excess isocyanate monomer, the above-mentioned polyol, and, if necessary, an alcohol other than the above-mentioned polyol are used. Can be produced by mixing and adding a urethanization reaction catalyst as needed.
Examples of the polyol include the same as those exemplified in the above-mentioned "polypoly".
Examples of the alcohol other than the polyol include those exemplified in the above-mentioned "Method for producing an isocyanurate group-containing polyisocyanate", excluding those exemplified in the above-mentioned "polyol".
The urethanization reaction catalyst is not particularly limited, and examples thereof include tin-based compounds, zinc-based compounds, and amine-based compounds.
The urethanization reaction temperature is preferably 50 ° C. or higher and 160 ° C. or lower, and more preferably 60 ° C. or higher and 120 ° C. or lower.
When the urethanization reaction temperature is not more than the above upper limit value, coloring of polyisocyanate and the like can be more effectively suppressed.
The urethanization reaction time is preferably 30 minutes or more and 4 hours or less, more preferably 1 hour or more and 3 hours or less, and further preferably 1 hour or more and 2 hours or less.
The ratio of the molar amount of the isocyanate group of the isocyanate monomer to the molar amount of the hydroxyl group of the polyol (and, if necessary, an alcohol other than the polyol) is preferably 2/1 or more and 50/1 or less. When the molar ratio is at least the above lower limit value, the polyisocyanate can have a lower viscosity. When the molar ratio is not more than the above upper limit, the yield of the urethane group-containing polyisocyanate can be further increased.

(7) Method for Producing Biuret Structure-Containing Polyisocyanate The biuret agent for inducing a biuret-structure-containing polyisocyanate from an isocyanate monomer is not particularly limited, and is, for example, water, a monohydric tertiary alcohol, or an acid acid. , Organic first monoamine, organic first diamine and the like.
The isocyanate group is preferably 6 mol or more, more preferably 10 mol or more, and further preferably 10 mol or more and 80 mol or less with respect to 1 mol of the biuret agent. When the molar amount of the isocyanate group per 1 mol of the biuret agent is at least the above lower limit value, the polyisocyanate has a sufficiently low viscosity, and when it is at least the above upper limit value, the low temperature curability when made into a resin film is further improved. do.

Further, a solvent may be used in the biuret formation reaction. The solvent may be any one that dissolves an isocyanate monomer and a biuret agent such as water to form a uniform phase under reaction conditions.
Specific examples of the solvent include ethylene glycol-based solvents and phosphoric acid-based solvents.
Examples of the ethylene glycol-based solvent include ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol mono-n-propyl ether acetate, ethylene glycol monoisopropyl ether acetate, ethylene glycol mono-n-butyl ether acetate, and ethylene glycol. Diacetate, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol di-n-propyl ether, ethylene glycol diisopropyl ether, ethylene glycol di-n-butyl ether, ethylene glycol methyl ethyl ether, ethylene glycol methyl isopropyl ether, ethylene glycol methyl- n-butyl ether, ethylene glycol ethyl-n-propyl ether, ethylene glycol ethyl isopropyl ether, ethylene glycol ethyl-n-butyl ether, ethylene glycol-n-propyl-n-butyl ether, ethylene glycol isopropyl-n-butyl ether, diethylene glycol monomethyl ether acetate , Diethylene glycol monoethyl ether acetate, diethylene glycol mono-n-propyl ether acetate, diethylene glycol monoisopropyl ether acetate, diethylene glycol mono-n-butyl ether acetate, diethylene glycol diacetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol di-n-propyl ether, diethylene glycol Diisopropyl ether, diethylene glycol di-n-butyl ether, diethylene glycol methyl ethyl ether, diethylene glycol methyl isopropyl ether, diethylene glycol methyl-n-propyl ether, diethylene glycol methyl-n-butyl ether, diethylene glycol ethyl isopropyl ether, diethylene glycol ethyl-n-propyl ether, diethylene glycol ethyl Examples thereof include -n-butyl ether, diethylene glycol-n-propyl-n-butyl ether, diethylene glycol isopropyl-n-butyl ether and the like.
Examples of the phosphoric acid-based solvent include trimethyl phosphate, triethyl phosphate, tripropyl phosphate, tributyl phosphate and the like.
These solvents may be used alone or in combination of two or more.
Among them, as the ethylene glycol solvent, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol diacetate or diethylene glycol dimethyl ether are preferable.
Further, as the phosphoric acid solvent, trimethyl phosphate or triethyl phosphate is preferable.

The biuret reaction temperature is preferably 70 ° C. or higher and 200 ° C. or lower, and more preferably 90 ° C. or higher and 180 ° C. or lower. When it is not more than the above upper limit value, coloring of polyisocyanate or the like tends to be prevented more effectively.

The above-mentioned allophanate-forming reaction, uretdione-forming reaction, iminooxadiazine-izing reaction, isocyanurate-forming reaction, urethanization reaction, and biuret-forming reaction may be carried out sequentially, and some of them may be carried out in parallel. May be good.
The unreacted isocyanate monomer can be removed from the reaction solution after completion of the reaction by thin film distillation, extraction or the like to obtain polyisocyanate.

Further, for the purpose of suppressing coloring during storage, for example, an antioxidant or an ultraviolet absorber may be added to the obtained polyisocyanate.
Examples of the antioxidant include hindered phenols such as 2,6-di-tert-butyl-p-cresol. Examples of the ultraviolet absorber include benzotriazole, benzophenone and the like. These antioxidants and ultraviolet absorbers may be used alone or in combination of two or more. The amount of these additions is preferably 10 mass ppm or more and 500 mass ppm or less with respect to the mass of the polyisocyanate.

(Average number of isocyanate functional groups of polyisocyanate)
The average number of isocyanate functional groups of the polyisocyanate is preferably 2 or more, more preferably 2 or more and 20 or less, further preferably 2 or more and 10 or less, and 2 or more and 9 or less in terms of enhancing the curability and cohesive force of the pressure-sensitive adhesive composition. It is particularly preferable, and 2 or more and 8 or less are most preferable.
The average number of isocyanate functional groups of polyisocyanate can be measured by using the method described in Examples described later.

[Crosslinking agent component (b2)]
The blocked polyisocyanate contained in the cross-linking agent component (b2) is a reaction product of the polyisocyanate and the blocking agent. That is, in the blocked polyisocyanate, at least a part of the isocyanate groups in the polyisocyanate are blocked with a blocking agent.

Examples of the polyisocyanate used for producing the blocked polyisocyanate include aliphatic or alicyclic polyisocyanates, which are the same as those exemplified in the above-mentioned “crosslinking agent component (b1)”.

(Blocking agent)
Specifically, as the blocking agent used for producing the blocked polyisocyanate, for example, 1) alcohol-based compound, 2) alkylphenol-based compound, 3) phenol-based compound, 4) active methylene-based compound, 5) mercaptan-based compound, 6 ) Acid amide compounds, 7) acid imide compounds, 8) imidazole compounds, 9) urea compounds, 10) oxime compounds, 11) amine compounds, 12) imide compounds, 13) heavy sulfites, 14 ) Pyrazole-based compounds, 15) Triazole-based compounds and the like. More specific examples of the blocking agent include those shown below.

1) Alcohol-based compounds: Alcohols such as methanol, ethanol, 2-propanol, n-butanol, sec-butanol, 2-ethyl-1-hexanol, 2-methoxyethanol, 2-etokashiethanol, 2-butoxyethanol and the like.
2) Alkylphenol compounds: Monos and dialkylphenols having an alkyl group having 4 or more carbon atoms as a substituent. Specific examples of the alkylphenol compound include n-propylphenol, iso-propylphenol, n-butylphenol, sec-butylphenol, tert-butylphenol, n-hexylphenol, 2-ethylhexylphenol, n-octylphenol, and n-nonylphenol. Monoalkylphenols such as: di-n-propylphenol, diisopropylphenol, isopropylcresol, di-n-butylphenol, di-tert-butylphenol, di-sec-butylphenol, di-n-octylphenol, di-2-ethylhexylphenol, etc. Dialkylphenols such as di-n-nonylphenol.
3) Phenolic compounds: phenol, cresol, ethylphenol, styrenated phenol, hydroxybenzoic acid ester, etc.
4) Active methylene compounds: malonic acid ester having a primary alkyl group such as dimethyl malonate, diethyl malonate, dipropyl malonic acid, dibutyl malonic acid, dicyclohexyl malonic acid, diphenyl malonic acid; di-sec-butyl malonic acid, Malonic acid ester having a secondary alkyl group such as diisopropyl malonic acid and isopropylethyl malonic acid; malon having a tertiary alkyl group such as di-tert-butyl malonic acid, di-tert-pentyl malonic acid and tert-butyl ethyl malonic acid. Acid ester; methyl acetoacetate, ethyl acetoacetate, methyl isobutanoylacetate, ethyl isobutanoylacetate, acetylacetone, etc.
5) Mercaptan compounds: Butyl mercaptan, dodecyl mercaptan, etc.
6) Acid amide compounds: acetanilide, acetate amide, ε-caprolactam, δ-valerolactam, γ-butyrolactam and the like.
7) Imide-based compounds: succinimide, maleic acid imide, etc.
8) Imidazole compounds: imidazole, 2-methylimidazole, etc.
9) Urea compounds: urea, thiourea, ethylene urea, etc.
10) Oxime compounds: formaldehyde, acetaldoxime, acetoxime, methylethylketooxime, cyclohexanone oxime and the like.
11) Amine-based compounds: diphenylamine, aniline, carbazole, din-propylamine, diisopropylamine, isopropylethylamine and the like.
12) Imine-based compounds: ethyleneimine, polyethyleneimine, etc.
13) Sodium bisulfite compound: sodium bisulfite or the like.
14) Pyrazole compounds: pyrazole, 3-methylpyrazole, 3,5-dimethylpyrazole and the like.
15) Triazole compounds: 3,5-dimethyl-1,2,4-triazole and the like.

Among the above blocking agents, the block polyisocyanate is composed of an active methylene compound, an oxime compound, an amine compound, a pyrazole compound and a triazole compound in terms of availability, viscosity, curing temperature and curing time of the obtained blocked polyisocyanate. At least one compound selected from the group is preferable, an active methylene compound is more preferable, and a malonic acid ester having a secondary alkyl group or a malonic acid ester having a tertiary alkyl group is further preferable.
Examples of the malonic acid ester having a secondary alkyl group and the malonic acid ester having a tertiary alkyl group include a compound represented by the following general formula (I) (hereinafter, may be referred to as “compound (I)”). Is. The blocking agent may contain the compound (I) alone or in combination of two or more. Above all, it is particularly preferable to use a malonic acid ester having a secondary alkyl group and a malonic acid ester having a tertiary alkyl group in combination as the blocking agent.

(In the general formula (I), R ¹¹ is selected from the group consisting of a hydroxy group; an alkyl group which may contain one or more substituents selected from the group consisting of a hydroxy group and an amino group; and a group consisting of a hydroxy group and an alkyl group. Amino group which may contain one or more substituents; an aryl group which may contain one or more substituents selected from the group consisting of a hydroxy group and an amino group; or a group consisting of a hydroxy group and an amino group. It is an alkoxy group which may contain one or more substituents which are selected from the above. However, the amino group may be cyclic.
^R12 , ^R13 and ^R14 are each independently a hydrogen atom; an alkyl group which may contain one or more substituents selected from the group consisting of a hydroxy group and an amino group; or a group consisting of a hydroxy group and an amino group. It is an aryl group which may contain one or more substituents which are more selected. The amino group may be cyclic. However, the number of hydrogen atoms in R ¹² , R ¹³ and R ¹⁴ is one or less. )

When R ¹¹ is an alkyl group having no substituent, the alkyl group preferably has 1 or more and 30 or less carbon atoms, more preferably 1 or more and 8 or less, and 1 or more and 6 or less. It is more preferable, and it is particularly preferable that it is 1 or more and 4 or less. Specific examples of the alkyl group having no substituent include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a tert-butyl group, a sec-butyl group, an isobutyl group, and an n-pentyl group. Isopentyl group, neopentyl group, tert-pentyl group, 1-methylbutyl group, n-hexyl group, 2-methylpentyl group, 3-methylpentyl group, 2,2-dimethylbutyl group, 2,3-dimethylbutyl group, n -Heptyl group, 2-methylhexyl group, 3-methylhexyl group, 2,2-dimethylpentyl group, 2,3-dimethylpentyl group, 2,4-dimethylpentyl group, 3,3-dimethylpentyl group, 3- Examples thereof include ethylpentyl group, 2,2,3-trimethylbutyl group, n-octyl group, isooctyl group, 2-ethylhexyl group, nonyl group, decyl group and the like.

When R ¹¹ is an alkyl group having a substituent, the substituent is a hydroxy group or an amino group.
Examples of the alkyl group containing a hydroxy group as the substituent include a hydroxymethyl group, a hydroxyethyl group, a hydroxypropyl group and the like.
Examples of the alkyl group containing an amino group as the substituent include an aminomethyl group, an aminoethyl group, an aminopropyl group, an aminobutyl group and the like.
Examples of the alkyl group containing a hydroxy group and an amino group as the substituent include a hydroxyaminomethyl group, a hydroxyaminoethyl group, a hydroxyaminopropyl group and the like.

When R ¹¹ is an amino group having a substituent, the substituent is a hydroxy group or an alkyl group.
Examples of the amino group having a hydroxy group as a substituent include a hydroxyamino group (-NH-OH).
Examples of the amino group having an alkyl group as a substituent include a methylamino group, an ethylamino group, an n-butylamino group, a dimethylamino group, a diethylamino group, a dipropylamino group, a diisopropylamino group and a di-n-butylamino. Examples thereof include a group, a di-tert-butylamino group, a di-sec-butylamino group, a diisobutylamino group, a 2,6-dimethylpiperidyl group and the like.
Examples of the amino group having a hydroxy group and an alkyl group as the substituent include a hydroxymethylene amino group, a hydroxyethylene amino group, a hydroxypropylene amino group, a hydroxybutylene amino group and the like.
Examples of the amino group in which the two substituents are linked to each other to form a ring include an ethyleneimino group, an azacyclobutyl group, a pyrrolidyl group, a piperidyl group, a 2,6-dimethylpiperidyl group and a hexamethyleneimino group. Cyclic secondary amino group of.

When R ¹¹ is an aryl group having no substituent, the aryl group preferably has 5 or more and 30 or less carbon atoms, more preferably 6 or more and 20 or less, and 6 or more and 14 or less. Is even more preferable. Specifically, the aryl group is, for example, a monocyclic aromatic hydrocarbon group, a bicyclic aromatic hydrocarbon group, a tricyclic aromatic hydrocarbon group, a tetracyclic aromatic hydrocarbon group, or a five-ring group. Examples thereof include aromatic hydrocarbon groups, 6-ring aromatic hydrocarbon groups, and 7-ring aromatic hydrocarbon groups.
Examples of the monocyclic aromatic hydrocarbon group include a phenyl group, a benzyl group, a tolyl group, an o-kisilyl group and the like.
Examples of the bicyclic aromatic hydrocarbon group include an indanyl group, an indenyl group, a pentarenyl group, an azulenyl group, a naphthyl group, a tetrahydronaphthyl group and the like.
Examples of the tricyclic aromatic hydrocarbon group include anthrasenyl group, fluorenyl group, phenalenyl group, phenanthrenyl group and the like.
Examples of the tetracyclic aromatic hydrocarbon group include a pyrenyl group, a naphthalsenyl group, a chrysenyl group and the like.
Examples of the pentacyclic aromatic hydrocarbon group include a perylenel group, a pisenyl group, a pentasenyl group and the like.
Examples of the hexacyclic aromatic hydrocarbon group include a naphthopyrenyl group and the like.
Examples of the 7-cyclic aromatic hydrocarbon group include a coronenyl group and the like.

When R ¹¹ is an aryl group having a substituent, the substituent is a hydroxy group or an amino group.
Examples of the aryl group containing a hydroxy group as a substituent include a phenol group and the like.
Examples of the aryl group containing an amino group as a substituent include an aniline group and the like.
Examples of the aryl group containing a hydroxy group and an amino group as the substituent include an aminophenol group (hydroxyaniline group) and the like.

When R ¹¹ is an alkoxy group having no substituent, the alkoxy group preferably has 1 or more and 30 or less carbon atoms, more preferably 1 or more and 8 or less, and 1 or more and 6 or less. It is more preferable, and it is particularly preferable that it is 1 or more and 4 or less. Specific examples of the alkoxy group include, for example, a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, an n-butoxy group, a tert-butoxy group, a sec-butoxy group, an isobutoxy group, an n-pentoxy group and an isopentoxy group. Neopentoxy group, tert-pentoxy group, 1-methylbutoxy group, n-hexitoxy group, 2-methylpentoxy group, 3-methylpentoxy group, 2,2-dimethylbutoxy group, 2,3-dimethylbutoxy group, n -Heptoxy group, 2-methylhexitoxy group, 3-methylhexitoxy group, 2,2-dimethylpentoxy group, 2,3-dimethylpentoxy group, 2,4-dimethylpentoxy group, 3,3-dimethylpentoxy group, Examples thereof include 3-ethylpentoxy group, 2,2,3-trimethylbutoxy group, n-octoxy group, isooctoxy group, 2-ethylhexitoxy group, noninoxy group, decyloxy group and the like.

When R ¹¹ is an alkoxy group having a substituent, the substituent is a hydroxy group or an amino group.
Examples of the alkoxy group containing a hydroxy group as a substituent include a hydroxymethyleneoxy group, a hydroxyethyleneoxy group, a hydroxypropyleneoxy group, a hydroxybutyleneoxy group and the like.
Examples of the alkoxy group containing an amino group as a substituent include an aminomethyleneoxy group, an aminoethyleneoxy group, an aminopropyleneoxy group, an aminobutyleneoxy group and the like.
Examples of the alkoxy group containing a hydroxy group and an amino group as the substituent include a hydroxyaminomethylidine oxy group, a hydroxy aminoethylidine oxy group, a hydroxy aminopropylene oxy group and the like.

Among them, as ^R11 , an alkoxy group having or not having a substituent is preferable, and an alkoxy group having no substituent is more preferable.

In the general formula (I), R ¹² , R ¹³ and R ¹⁴ are each independently an alkyl group which may contain one or more substituents selected from the group consisting of a hydrogen atom; a hydroxy group and an amino group; or hydroxy. It is an aryl group which may contain one or more substituents selected from the group consisting of a group and an amino group. The amino group may be formed by connecting the two substituents to each other to form a ring. However, the number of hydrogen atoms in R ¹² , R ¹³ and R ¹⁴ is one or less.
Examples of the above-mentioned alkyl group and the above-mentioned aryl group include the same as those exemplified in the above-mentioned “R ¹¹ ”.
Examples of the amino group in which the above two substituents are linked to each other to form a ring include a cyclic secondary amino group such as an ethyleneimino group, an azacyclobutyl group, a pyrrolidyl group and a piperidyl group.
Among them, it is preferable that R ¹² is an alkyl group having or not having a hydrogen atom or a substituent, and R ¹³ and R ¹⁴ are independently alkyl groups having or not having a substituent, respectively ^. Alkyl groups that are alkyl groups that do not have hydrogen atoms or substituents, and that R ¹³ and R ¹⁴ do not have substituents independently are more preferable.

Specific preferred compounds (I) are malonic acid esters having a secondary alkyl group such as diisopropyl malonic acid, isopropylethyl malonate, and di-sec-butyl malonic acid; tert-butylethyl malonic acid, malon. Examples thereof include malonic acid esters having a tertiary alkyl group such as di-tert-butyl acid and di-tert-pentyl malonic acid.
Among them, diisopropyl malonate is particularly preferable when the compound (I) is a malonic acid ester having a secondary alkyl group, and malonic acid is particularly preferable when the compound (I) is a malonic acid ester having a tertiary alkyl group. Di-tert-butyl acid acid is particularly preferred.

(Manufacturing method of blocked polyisocyanate)
The blocked polyisocyanate is obtained, for example, by reacting the polyisocyanate with the above-mentioned blocking agent.
The blocking reaction between the polyisocyanate and the blocking agent can be carried out regardless of the presence or absence of a solvent, and a blocked polyisocyanate can be obtained.

The mixing ratio of the polyisocyanate and the blocking agent is such that the molar ratio of the active hydrogen groups contained in the blocking agent when the isocyanate group contained in the polyisocyanate is 1 is the molar ratio of the active hydrogen groups contained in the polyisocyanate from the viewpoint of the storage stability of the pressure-sensitive adhesive composition. It is preferably 0.5 or more and 3.0 or less, more preferably 0.8 or more and 2.0 or less, more preferably 0.9 or more and 1.5 or less, and 0.9 or more and 1. It is more preferably 3 or less, and particularly preferably 0.9 or more and 1.2 or less.

In the blocking reaction, an organic metal salt such as tin, zinc or lead, a tertiary amine compound, an alkali metal alcoholate such as sodium or the like may be used as a catalyst.
The amount of the catalyst added varies depending on the temperature of the blocking reaction and the like, but is usually 0.05 parts by mass or more and 1.5 parts by mass or less with respect to 100 parts by mass of polyisocyanate, and 0.1 parts by mass. It is preferably 1.0 part by mass or less.

The blocking reaction can generally be carried out at −20 ° C. or higher and 150 ° C. or lower, preferably 0 ° C. or higher and 130 ° C. or lower, and more preferably 10 ° C. or higher and 120 ° C. or lower. When the temperature of the blocking reaction is at least the above lower limit value, the reaction rate can be further increased, and when it is at least the above upper limit value, the side reaction can be further suppressed.
After the blocking reaction, a neutralization treatment may be performed by adding an acidic compound or the like.
As the acidic compound, an inorganic acid may be used or an organic acid may be used. Examples of the inorganic acid include hydrochloric acid, phosphoric acid, phosphoric acid and the like. Examples of the organic acid include methanesulfonic acid, p-toluenesulfonic acid, dioctylphthalate, dibutylphthalate and the like.

The end of the reaction can be determined by confirming the disappearance or decrease of the isocyanate group by using, for example, infrared spectroscopic analysis.

When a solvent is used, a solvent that is inert to the isocyanate group may be used.
When a solvent is used, the content of the solid content derived from the polyisocyanate and the blocking agent with respect to 100 parts by mass of the blocked polyisocyanate composition may be usually 10 parts by mass or more and 95 parts by mass or less, and 15 parts by mass or more and 90 parts by mass. It is preferably 20 parts by mass or less, and more preferably 20 parts by mass or more and 85 parts by mass or less.

[Physical characteristics of the cross-linking agent component (b)]
The weight average molecular weight Mw of the cross-linking agent component (b1) and the cross-linking agent component (b2) is preferably 8.0 × 10 ² or more and 1.0 × 10 ⁵ or less, and 1.0 × 10 ³ or more and 8.0 × 10 respectively. ⁴ or less is more preferable, and 1.5 × 10 ³ or more and 7.0 × 10 ⁴ or less is further preferable. When the weight average molecular weight Mw is within the above range, the viscosities of the cross-linking agent component (b1) and the cross-linking agent component (b2) can be kept better. The weight average molecular weight Mw can be measured, for example, by gel permeation chromatography (hereinafter, may be abbreviated as “GPC”).

<Level 2 or Level 3 alcohol (c)>
The pressure-sensitive adhesive composition of the present embodiment contains a secondary or tertiary alcohol (c) when the cross-linking agent component (b1) is contained. By containing a predetermined amount of the secondary or tertiary alcohol (c), the pressure-sensitive adhesive composition of the present embodiment is excellent in cohesive power and pot life while maintaining good adhesiveness after heat curing.

Examples of the secondary or tertiary alcohol (c) include secondary alcohols such as isopropyl alcohol and isobutyl alcohol; and tertiary alcohols such as tert-butyl alcohol. These secondary or tertiary alcohols may be used alone or in combination of two or more. Further, only the secondary alcohol or only the tertiary alcohol may be used, or the secondary alcohol and the tertiary alcohol may be used in combination.

Among them, the secondary or tertiary alcohol (c) preferably contains a tertiary alcohol, more preferably contains tert-butyl alcohol, and further preferably tert-butyl alcohol.

<Other ingredients>
The pressure-sensitive adhesive composition of the present embodiment may further contain other additives.
Examples of other additives include curing agents other than the cross-linking agent component (b) capable of reacting with the cross-linking functional group in the acrylic polymer (a), a curing catalyst, a solvent, and pigments (constituent pigment, coloring pigment, metallic). Pigments, etc.), photopolymerization initiators, UV absorbers, light stabilizers, radical stabilizers, anti-yellowing agents that suppress coloration during the baking process, coating surface adjusters, flow conditioners, pigment dispersants, defoaming agents, etc. Examples thereof include thickeners and film-forming aids.

Examples of the curing agent include melamine resin, urea resin, epoxy group-containing compound or resin, carboxyl group-containing compound or resin, acid anhydride, alkoxysilane group-containing compound or resin, hydrazide compound and the like.

The curing catalyst may be a basic compound or a Lewis acidic compound.
Examples of the basic compound include metal hydroxides, metal alkoxides, metal carboxylates, metal acetyl acetylates, hydroxides of onium salts, onium carboxylates, halides of onium salts, and metal salts of active methylene compounds. Examples thereof include onium salts of active methylene compounds, aminosilanes, amines, phosphins and the like. As the onium salt, an ammonium salt, a phosphonium salt or a sulfonium salt is suitable.
Examples of the Lewis acidic compound include an organic tin compound, an organic zinc compound, an organic titanium compound, and an organic zirconium compound.

Examples of the solvent include 1-methylpyrrolidone, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, propylene glycol monomethyl ether, and 3-methoxy-3-methyl. -1-Butanol, ethylene glycol diethyl ether, diethylene glycol diethyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, dipropylene glycol dimethyl ether (DPDM), propylene glycol dimethyl ether, methyl ethyl ketone, acetone, methyl isobutyl ketone, propylene glycol monomethyl ether acetate, ethanol, methanol , Iso-propanol, 1-propanol, iso-butanol, 1-butanol, tert-butanol, 2-ethylhexanol, cyclohexanol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,4-butane Examples thereof include diol, 1,3-butanediol, ethyl acetate, isopropyl acetate, butyl acetate, toluene, xylene, pentane, iso-pentane, hexane, iso-hexane, cyclohexane, solvent naphtha, and mineral spirit. These solvents may be used alone or in combination of two or more.

In addition, pigments (constitution pigments, coloring pigments, metallic pigments, etc.), ultraviolet absorbers, light stabilizers, radical stabilizers, anti-yellowing agents that suppress coloring during the baking process, coating surface adjusting agents, flow adjusting agents, pigments As the dispersant, defoaming agent, thickener and film-forming auxiliary, known ones can be appropriately selected and used.

<Manufacturing method of adhesive composition>
The pressure-sensitive adhesive composition can be produced by a conventionally known method. For example, a melt-kneading method using a general miscible machine such as a Banbury mixer, a single-screw extruder, a twin-screw extruder, a conider, or a multi-screw screw extruder. A method of heating and removing the solvent after coating on the Kizai film is used.

The pressure-sensitive adhesive composition of the present embodiment may be foamed in order to reduce the weight, make it softer, and improve the adhesiveness. Examples of the foaming method include a chemical method, a physical method, and the use of a heat-expandable microballoon. Bubbles can be distributed inside the material by adding a chemical foaming agent such as an inorganic foaming agent or an organic foaming agent, a physical foaming agent, or the like, or by adding a heat-expandable microballoon.

Further, by adding a hollow filler (already inflated balloon), weight reduction, flexibility, and improvement of adhesion may be achieved.

In the pressure-sensitive adhesive composition of the present embodiment, a pressure-sensitive adhesive resin may be added for adjusting the pressure-sensitive adhesive force and the cohesive force. Examples of the tackifying resin include a rosin-based tackifier resin, a terpene-based tackifier resin, a petroleum-based tackifier resin, and a styrene-based tackifier resin. These tackifier resins may be used alone or in combination of two or more. Further, the softening point of the tackifier resin is preferably 90 ° C. or higher and 160 ° C. or lower.

≪Cursed product≫
The cured product of the present embodiment is obtained by curing the above-mentioned pressure-sensitive adhesive composition by heat or light.
The cured product of this embodiment has good adhesiveness.

The cured product of the present embodiment is obtained, for example, by dissolving the above-mentioned pressure-sensitive adhesive composition in a soluble solvent, applying it on an adherend using a coater or the like, drying it if necessary, and then heating or heating. It can be manufactured by curing with light.
Examples of the method of applying the pressure-sensitive adhesive composition onto the adherend include a method of applying the pressure-sensitive adhesive composition using an applicator, a roll coater, a knife coater, a gravure coater, or the like. When drying is performed after the coating, for example, a heat-drying method in which the obtained laminate is placed in a dryer or the like and dried at a temperature of 50 ° C. or higher and 150 ° C. or lower for 1 minute or longer and 30 minutes or lower can be mentioned. .. Alternatively, other drying methods include, for example, natural drying, hot air drying, infrared drying and the like.

In the case of heat curing, the heating temperature can be 70 ° C. or higher and 150 ° C. or lower, 75 ° C. or higher and 145 ° C. or lower, and 80 ° C. or higher and 140 ° C. or lower.

In the case of curing by light, examples of light include ultraviolet rays and the like. Examples of the method of irradiating ultraviolet rays include a method using a known ultraviolet light irradiation device such as a xenon lamp, a xenon-mercury lamp, a metal halide lamp, a high-pressure mercury lamp, and a low-pressure mercury lamp. The irradiation amount of ultraviolet rays can be, for example, in the range of 0.01 J / cm ² or more and 5 J / cm ² or less.

≪Adhesive sheet≫
The pressure-sensitive adhesive sheet of the present embodiment includes a base material and a pressure-sensitive adhesive layer on the base material.
The pressure-sensitive adhesive layer is made of a cured product of the pressure-sensitive adhesive composition described above.
In the pressure-sensitive adhesive sheet of the present embodiment, the pressure-sensitive adhesive layer has excellent adhesiveness.

The base material is not particularly limited, but for example, paper such as high-quality paper, coated paper, cast-coated paper, heat-sensitive paper, and inkjet paper; cloth such as woven cloth and non-woven cloth; polyvinyl chloride, synthetic paper, and polyethylene terephthalate (PET). ), Polypropylene, polyethylene, cellulose triacetate, cellulose diacetate, polystyrene, polycarbonate, nylon, polyvinyl alcohol, ethylene-vinyl acetate copolymer, resin film such as polyimide; porous resin film such as porous polypropylene film; PET, polyolefin Etc., a vapor-deposited film obtained by metal-depositing aluminum or the like; a metal foil or the like is exemplified. The base material may be one whose surface has been peeled off.

In the pressure-sensitive adhesive sheet of the present embodiment, the thickness of the pressure-sensitive adhesive layer can be appropriately determined depending on the intended use, but is preferably 0.1 μm or more and 1000 μm or less, and 0.5 μm or more and 900 μm or less. It is more preferably 1 μm or more and 800 μm or less, and particularly preferably 3 μm or more and 700 μm or less.

The pressure-sensitive adhesive sheet of the present embodiment can be produced, for example, by applying a pressure-sensitive adhesive composition on a substrate, drying it if necessary, and then curing it. Examples of the coating method and the curing method include the same methods as those exemplified in the above-mentioned "cured product".

The pressure-sensitive adhesive sheet of the present embodiment includes a pressure-sensitive adhesive layer having a thickness of 45 μm, which is obtained by applying the pressure-sensitive adhesive composition onto a peel-treated polyethylene terephthalate film having a thickness of 38 μm, drying at 130 ° C. for 3 minutes, and curing the pressure-sensitive adhesive composition. The adhesive sheet was stored in an environment of 23 ° C. and 50% RH for 7 days, then immersed in ethyl acetate at 23 ° C. for 1 week, and dried at 120 ° C. for 2 hours. It is more preferably 25% by mass or more and 98% by mass or less, further preferably 33% by mass or more and 98% by mass or less, and particularly preferably 35% by mass or more and 98% by mass or less. , 37% by mass or more and 98% by mass or less is most preferable. When the gel fraction is within the above range, the curability is more excellent.

The pressure-sensitive adhesive sheet of the present embodiment has a width of 20 mm and includes a pressure-sensitive adhesive layer having a thickness of 45 μm, which is obtained by coating the pressure-sensitive adhesive composition on a polyethylene terephthalate film having a thickness of 25 μm, drying at 130 ° C. for 3 minutes, and curing the pressure-sensitive adhesive composition. An adhesive sheet having a length of 100 mm is stored at 23 ° C. in a 50% RH environment for 7 days, then crimped once with a 2 kg roller using a SUS304BA steel plate as an adherend, cured at 23 ° C. for 30 minutes, and then 23 ° C. The 180 degree peel adhesive force measured at a speed of 300 mm / min is preferably 0.05 N / 20 mm or more and 40 N / 20 mm or less, more preferably 0.1 N / 20 mm or more and 40 N / 20 mm or less, and 0. It is more preferably 1 N / 20 mm or more and 38 N / 20 mm or less, particularly preferably 0.1 / 20 mm or more and 35 N / 20 mm or less, and most preferably 0.1 / 20 mm or more and 33 N / 20 mm or less.

Hereinafter, the present embodiment will be described in more detail based on Examples and Comparative Examples, but the present embodiment is not limited to the following Examples.

<Test items>
The acrylic polymer, polyisocyanate component and blocked polyisocyanate component obtained in the synthetic example were measured and evaluated for their physical properties according to the methods shown below.

[Physical characteristics 1]
(Isocyanate group (NCO) content)
In order to measure the NCO content of the polyisocyanate component, the polyisocyanate before being blocked by the blocking agent was used as a measurement sample for the blocked polyisocyanate component.

First, 2 g or more and 3 g or less of the measurement sample were precisely weighed in a flask (Wg). Then, 20 mL of toluene was added to dissolve the measurement sample. Then, 20 mL of a toluene solution of 2N-butylamine was added, and after mixing, the mixture was allowed to stand at room temperature for 15 minutes. Then 70 mL of isopropyl alcohol was added and mixed. This solution was then titrated into an indicator with a 1N hydrochloric acid solution (Factor F). The obtained titration value was V2 mL. Then, without the polyisocyanate sample, the obtained titration value was set to V1 ml. Next, the isocyanate group (NCO) content (% by mass) of the polyisocyanate was calculated from the following formula.

Isocyanate group (NCO) content (% by mass) = (V1-V2) x F x 42 / (W x 1000) x 100

[Physical characteristics 2]
(Number average molecular weight and weight average molecular weight)
The number average molecular weight and the weight average molecular weight are the polystyrene-based number average molecular weight and the weight average molecular weight measured by gel permeation chromatography (GPC) using the following apparatus. In order to measure the number average molecular weight of the polyisocyanate component, the polyisocyanate before being blocked by the blocking agent was used as a measurement sample for the blocked polyisocyanate component. As for the weight average molecular weight, the blocked polyisocyanate component was used as it was as a measurement sample. The measurement conditions are shown below.

(Measurement condition)
Equipment: HLC-802A manufactured by Tosoh Corporation
Column: Made by Tosoh Corporation, G1000HXL x 1
G2000HXL x 1
G3000HXL x 1 Carrier: Tetrahydrofuran Detection method: Differential refractometer

[Physical characteristics 3]
(Average number of isocyanate functional groups)
The average number of isocyanate functional groups (average number of NCOs) of the polyisocyanate component was calculated by the following formula. In the formula, “Mn” is the number average molecular weight of the polyisocyanate component before being blocked by the blocking agent for the blocked polyisocyanate component, and the value measured in the above “Physical characteristics 2” was used. The "NCO content" is the isocyanate group content of the polyisocyanate component measured before blocking with the blocking agent for the blocked polyisocyanate component, and the value calculated in the above "Physical characteristics 1" was used.

Average number of isocyanate functional groups = (Mn x NCO content x 0.01) / 42

[Physical characteristics 4]
(Solid content of polyisocyanate or blocked polyisocyanate)
The solid content of the polyisocyanate or the blocked polyisocyanate was determined as follows.
First, an aluminum dish having a bottom diameter of 38 mm was precisely weighed. Then, about 1 g of the polyisocyanate or the blocked polyisocyanate produced in Examples and Comparative Examples was placed on an aluminum dish and weighed precisely (W1). Then, the polyisocyanate or the blocked polyisocyanate was adjusted to a uniform thickness. Then, the polyisocyanate or the blocked polyisocyanate in the state of being placed on an aluminum dish was held in an oven at 105 ° C. for 1 hour. Then, after the aluminum dish reached room temperature, the polyisocyanate or block polyisocyanate remaining in the aluminum dish was precisely weighed (W2). Next, the solid content (mass%) of the polyisocyanate or the blocked polyisocyanate was calculated from the following formula.

Solid content (% by mass) of polyisocyanate or blocked polyisocyanate
= W2 / W1 × 100

[Physical characteristics 5]
(Glass transition temperature Tg)
The glass transition temperature of the acrylic polymer is such that the organic solvent and water in the acrylic polymer solution are blown under reduced pressure and then vacuum-dried, and the temperature is raised to 5 ° C. using a differential scanning calorimetry (DSC) measuring device. The value measured under the condition of / minute was used as the glass transition temperature.

[Preparation of adhesive sheet 1]
(Preparation of adhesive sheet for measuring 180 degree peel adhesive strength)
The pressure-sensitive adhesive compositions obtained in Examples and Comparative Examples were coated on a 25 μm polyethylene terephthalate (PET) film by an applicator so as to have a thickness of 45 μm after drying, and dried at 130 ° C. for 3 minutes. Then, it was stored in the environment of 23 ° C. and 50% RH for 7 days to obtain a pressure-sensitive adhesive sheet for measuring 180-degree peel adhesive strength. Those with a short pot life and gelation were applied before gelation. On the other hand, for those that did not gel immediately after adjustment, a pressure-sensitive adhesive composition was prepared and coated after 8 hours to prepare a pressure-sensitive adhesive sheet for measuring 180-degree peel adhesive strength.

[Preparation of adhesive sheet 2]
(Preparation of adhesive sheet for measuring gel fraction)
The pressure-sensitive adhesive compositions obtained in Examples and Comparative Examples were coated on a peel-treated PET film having a thickness of 38 μm by an applicator so that the thickness after drying was 45 μm, and dried at 130 ° C. for 3 minutes. .. Then, it was stored in the environment of 23 ° C. and 50% RH for 7 days to obtain an adhesive sheet for measuring the gel fraction.

[Evaluation 1]
(Pot life)
The viscosity of the pressure-sensitive adhesive compositions obtained in Examples and Comparative Examples was measured after storage for 8 hours in a 23 ° C. and 50% RH environment. The thickening rate (double) was calculated using the following formula. Those that do not gel after 8 hours are evaluated as having a good pot life, those having a thickening rate of 2 times or less are evaluated as having a better pot life, and those having a thickening rate close to 1 time. Alternatively, those having a pot life of 1 times or less were evaluated as having a better pot life, and those having a thickening rate of 0.9 times or more and 1.1 times or less were evaluated to be particularly good.

(Viscosity increase rate) = (Viscosity of the pressure-sensitive adhesive composition after 8 hours of storage) / (Viscosity of the pressure-sensitive adhesive composition immediately after compounding)

[Evaluation 2]
(180 degree peel adhesive strength)
The adhesive sheet obtained by the above method was cut into a width of 20 mm and a length of 100 mm to obtain a test piece. Using a steel plate of SUS304BA as an adherend, a 2 kg roller was reciprocated once to press the test piece against the steel plate, and after curing at 23 ° C. for 30 minutes, the peel adhesive strength of 180 degrees was measured at a speed of 300 mm / min. Those having a 180-degree peel adhesive strength of 0.05 N / 20 mm or more (those having adhesiveness) were evaluated as having good adhesiveness.

For Examples 1 to 17, 22 and Comparative Example 4, the adhesive strength retention rate (%) was calculated using the following formula. Those having an adhesive strength retention rate of 90% or more and 130% or less were evaluated as having good adhesive retention.

(Adhesive retention rate) =
{(180 degree peel adhesive strength of adhesive composition containing secondary or tertiary alcohol) / (180 degree peel adhesive strength of adhesive composition not containing secondary or tertiary alcohol)} × 100

That is, with respect to the pressure-sensitive adhesive compositions obtained in Examples 1 to 4, 9 to 16 and Comparative Example 4, the 180-degree peel adhesive strength of the pressure-sensitive adhesive composition obtained in Comparative Example 1 was "class 2 or 3". The adhesive strength retention rate was calculated using the above formula as "180 degree peel adhesive strength of the pressure-sensitive adhesive composition containing no alcohol".
Further, with respect to the pressure-sensitive adhesive compositions obtained in Examples 5 to 6, the 180-degree peel adhesive strength of the pressure-sensitive adhesive composition obtained in Comparative Example 2 was set to "a pressure-sensitive adhesive not containing a secondary or tertiary alcohol." The adhesive strength retention rate was calculated using the above formula as "180 degree peel adhesive strength of the composition".
Further, with respect to the pressure-sensitive adhesive compositions obtained in Examples 7 to 8, the 180-degree peel adhesive strength of the pressure-sensitive adhesive composition obtained in Comparative Example 3 was set to "a pressure-sensitive adhesive not containing a secondary or tertiary alcohol." The adhesive strength retention rate was calculated using the above formula as "180 degree peel adhesive strength of the composition".
Regarding the pressure-sensitive adhesive composition obtained in Example 17, the 180-degree peel adhesive strength of the pressure-sensitive adhesive composition obtained in Comparative Example 6 was set to "a pressure-sensitive adhesive composition not containing a secondary or tertiary alcohol." The adhesive strength retention rate was calculated using the above formula as "180 degree peel adhesive strength".
Regarding the pressure-sensitive adhesive composition obtained in Example 22, the pressure-sensitive adhesive composition obtained in Comparative Example 5 had a 180-degree peel adhesive strength of "a pressure-sensitive adhesive composition not containing a secondary or tertiary alcohol". The adhesive strength retention rate was calculated using the above formula as "180 degree peel adhesive strength".

[Evaluation 3]
(Gel fraction)
About 0.1 g or more and 0.2 g or less of the pressure-sensitive adhesive sheet obtained by the above method was collected, wrapped in a mesh-like sheet, immersed in ethyl acetate for 1 week, and then dried at 120 ° C. for 2 hours. Then, the gel fraction (% by mass) was calculated using the following formula. Those having a gel fraction of 20% by mass or more were evaluated as having good curability.

(Gel fraction)
= (Sample mass after drying) / (Sample mass before adding ethyl acetate) x 100

In Examples 1 to 17 and 22, and Comparative Example 4, the gel fraction retention rate (%) was calculated using the following formula. Those having a gel fraction retention rate of 90% or more were evaluated as having good curability retention.

(Gel fraction retention rate) =
((Gel fraction of pressure-sensitive adhesive composition containing secondary or tertiary alcohol) / (Gel fraction of pressure-sensitive adhesive composition containing no secondary or tertiary alcohol)) × 100

That is, for the pressure-sensitive adhesive compositions obtained in Examples 1 to 4, 9 to 16 and Comparative Example 4, the gel fraction of the pressure-sensitive adhesive composition obtained in Comparative Example 1 was set to "secondary or tertiary alcohol. The gel fraction retention rate was calculated using the above formula as the "gel fraction of the non-blended pressure-sensitive adhesive composition".
Regarding the pressure-sensitive adhesive compositions obtained in Examples 5 to 6, the gel fraction of the pressure-sensitive adhesive composition obtained in Comparative Example 2 was set to "a pressure-sensitive adhesive composition not containing a secondary or tertiary alcohol." The gel fraction retention rate was calculated using the above formula as the "gel fraction of".
Regarding the pressure-sensitive adhesive compositions obtained in Examples 7 to 8, the gel fraction of the pressure-sensitive adhesive composition obtained in Comparative Example 3 was set to "a pressure-sensitive adhesive composition not containing a secondary or tertiary alcohol." The gel fraction retention rate was calculated using the above formula as the "gel fraction of".
Regarding the pressure-sensitive adhesive composition obtained in Example 17, the gel fraction of the pressure-sensitive adhesive composition obtained in Comparative Example 6 was set to "Gel of the pressure-sensitive adhesive composition not containing a secondary or tertiary alcohol". The gel fraction retention rate was calculated using the above formula as the fraction.
Regarding the pressure-sensitive adhesive composition obtained in Example 22, the gel fraction of the pressure-sensitive adhesive composition obtained in Comparative Example 5 was set to "Gel of the pressure-sensitive adhesive composition not containing a secondary or tertiary alcohol". The gel fraction retention rate was calculated using the above formula as the fraction.

<Synthesis of acrylic polymer (a)>
[Synthesis Example 1-1]
(Synthesis of acrylic polymer a-1)
97 parts by mass of n-butyl acrylate (BA) and 3 parts by mass of acrylic acid (AA) were put into a four-necked flask equipped with a stirrer, a thermometer, a nitrogen gas introduction tube and a cooling tube, and ethyl acetate was used as a solvent. 150 parts by mass was charged. Next, 0.15 parts by mass of 2,2'-azobisisobutyronitrile (AIBN) was added as a polymerization initiator while stirring under a nitrogen gas atmosphere, and the reaction was carried out at 65 ° C. for 8 hours. After the reaction, the mixture was cooled to obtain an acrylic polymer a-1 having a solid content concentration of 40% by mass. The weight average molecular weight Mw measured excluding the solvent of the acrylic polymer a- ¹ was 6.8 × 105, and the glass transition temperature Tg was −52.2 ° C.

[Synthesis Example 1-2]
(Synthesis of acrylic polymer a-2)
In a four-necked flask equipped with a stirrer, a thermometer, a nitrogen gas introduction tube and a cooling tube, 82 parts by mass of 2-ethylhexyl acrylate (2EHA), 14 parts by mass of methyl acrylate (MA), and acrylic acid (AA). 4 parts by mass was added, and 150 parts by mass of ethyl acetate was added as a solvent. Next, 0.15 parts by mass of AIBN was added as a polymerization initiator while stirring under a nitrogen gas atmosphere, and the reaction was carried out at 63 ° C. for 8 hours. After the reaction, the mixture was cooled to obtain an acrylic polymer a-2 having a solid content concentration of 40% by mass. The weight average molecular weight Mw measured by removing the solvent of the acrylic polymer a- ² was 6.6 × 105, and the glass transition temperature Tg was −58.1 ° C.

[Synthesis Example 1-3]
(Synthesis of acrylic polymer a-3)
96.4 parts by mass of n-butyl acrylate (BA) and 0.6 parts by mass of 4-hydroxybutyl acrylate (4-HBA) in a four-necked flask equipped with a stirrer, a thermometer, a nitrogen gas introduction tube and a cooling tube. And 3 parts by mass of acrylic acid (AA) were added, and 150 parts by mass of ethyl acetate was added as a solvent. Next, 0.15 parts by mass of AIBN was added as a polymerization initiator while stirring under a nitrogen gas atmosphere, and the reaction was carried out at 65 ° C. for 8 hours. After the reaction, the mixture was cooled to obtain an acrylic polymer a-3 having a solid content concentration of 40% by mass. The weight average molecular weight Mw measured excluding the solvent of the acrylic polymer a- ³ was 6.9 × 105, and the glass transition temperature Tg was −52.1 ° C.

[Synthesis Example 1-4]
(Synthesis of acrylic polymer a-4)
81.5 parts by mass of 2-ethylhexyl acrylate (2EHA) and 0.5 of 4-hydroxybutyl acrylate (4-HBA) in a four-necked flask equipped with a stirrer, a thermometer, a nitrogen gas introduction tube and a cooling tube. 14 parts by mass of methyl acrylate (MA), 4 parts by mass of acrylic acid (AA) were added, and 150 parts by mass of ethyl acetate was added as a solvent. Next, 0.15 parts by mass of AIBN was added as a polymerization initiator while stirring under a nitrogen gas atmosphere, and the reaction was carried out at 63 ° C. for 8 hours. After the reaction, the mixture was cooled to obtain an acrylic polymer a-4 having a solid content concentration of 40% by mass. The weight average molecular weight Mw measured by removing the solvent of the acrylic polymer a- ⁴ was 6.8 × 105, and the glass transition temperature Tg was −57.9 ° C.

[Synthesis Example 1-5]
(Synthesis of acrylic polymer a-5)
96 parts by mass of 2-ethylhexyl acrylate (2EHA) and 4 parts by mass of acrylic acid (AA) were put into a four-necked flask equipped with a stirrer, a thermometer, a nitrogen gas introduction tube and a cooling tube, and used as a solvent. 150 parts by mass of ethyl acetate was added. Next, 0.15 parts by mass of AIBN was added as a polymerization initiator while stirring under a nitrogen gas atmosphere, and the reaction was carried out at 62 ° C. for 8 hours. After the reaction, the mixture was cooled to obtain an acrylic polymer a-5 having a solid content concentration of 40% by mass. The weight average molecular weight Mw measured excluding the solvent of the acrylic polymer a- ⁵ was 6.9 × 105, and the glass transition temperature Tg was -66.2 ° C.

[Synthesis Example 1-6]
(Synthesis of acrylic polymer a-6)
96 parts by mass of isononyl acrylate (iNA) and 4 parts by mass of acrylic acid (AA) were put into a four-necked flask equipped with a stirrer, a thermometer, a nitrogen gas introduction tube and a cooling tube, and ethyl acetate 150 was added as a solvent. The mass part was charged. Next, 0.15 parts by mass of AIBN was added as a polymerization initiator while stirring under a nitrogen gas atmosphere, and the reaction was carried out at 61 ° C. for 8 hours. After the reaction, the mixture was cooled to obtain an acrylic polymer a-6 having a solid content concentration of 40% by mass. The weight average molecular weight Mw measured excluding the solvent of the acrylic polymer a- ⁶ was 7.2 × 105, and the glass transition temperature Tg was −54.2 ° C.

[Synthesis Example 1-7]
(Synthesis of acrylic polymer a-7)
96 parts by mass of 2-ethylhexyl acrylate (2EHA) and 4 parts by mass of acrylic acid (AA) were put into a four-necked flask equipped with a stirrer, a thermometer, a nitrogen gas introduction tube and a cooling tube, and used as a solvent. 150 parts by mass of ethyl acetate was added. Next, 0.15 parts by mass of AIBN was added as a polymerization initiator while stirring under a nitrogen gas atmosphere, and the reaction was carried out at 62 ° C. for 8 hours. After the reaction, the mixture was cooled to obtain an acrylic polymer a-7 having a solid content concentration of 40% by mass. The weight average molecular weight Mw measured excluding the solvent of the acrylic polymer a- ⁷ was 6.9 × 105, and the glass transition temperature Tg was -66.2 ° C.

[Synthesis Example 1-8]
(Synthesis of acrylic polymer a-8)
87 parts by mass of 2-ethylhexyl acrylate (2EHA), 10 parts by mass of N-vinylpyrrolidone, and 4-hydroxybutyl acrylate (4-hydroxybutyl acrylate) in a four-necked flask equipped with a stirrer, a thermometer, a nitrogen gas introduction tube and a cooling tube. 4-HBA) 3 parts by mass was added, and 150 parts by mass of ethyl acetate was added as a solvent. Next, 0.15 parts by mass of AIBN was added as a polymerization initiator while stirring under a nitrogen gas atmosphere, and the reaction was carried out at 65 ° C. for 8 hours. After the reaction, the mixture was cooled to obtain an acrylic polymer a-8 having a solid content concentration of 40% by mass. The weight average molecular weight Mw measured excluding the solvent of the acrylic polymer a- ⁸ was 6.6 × 105, and the glass transition temperature Tg was −57.1 ° C.

<Synthesis of polyisocyanate and blocked polyisocyanate>
[Synthesis Example 2-1]
(Synthesis of polyisocyanate P-1)
A four-necked flask equipped with a thermometer, a stirring blade, and a reflux cooling tube was charged with 100 parts by mass of hexamethylene diisocyanate (HDI) under a nitrogen stream, and a trifunctional polycaprolactone polyol (Dycel Chemical Co., Ltd., "Plaxel". 308 ”(trade name), average number of hydroxyl functional groups: 3, number average molecular weight 850, hydroxyl value 195 mgKOH / g) 224.9 parts by mass (amount of NCO / OH = 15.2) in the reactor The temperature was maintained at 100 ° C. and maintained for 110 minutes. The reaction was stopped when the yield reached 41% by mass. After filtering the reaction solution, unreacted HDI was removed by a thin film distillation apparatus to obtain polyisocyanate P-1. The obtained polyisocyanate P-1 has an NCO content of 9.3% by mass, an average number of isocyanate functional groups of 3.9, a number average molecular weight Mn of 1.76 × 10 ³ , and a weight average molecular weight of Mw of 2.62 × 10. It was ³ . Further, ¹ H-NMR analysis and IR spectrum analysis were performed on the obtained polyisocyanate P-1, and it was confirmed that the urethane structure was present.

[Synthesis Example 2-2]
(Synthesis of Block Polyisocyanate BP-1)
Diisopropyl malonate with respect to 100 mol% of the isocyanate group of the polyisocyanate P-1 obtained in Synthesis Example 2-1 under a nitrogen stream in a four-necked flask equipped with a thermometer, a stirring blade, and a reflux condenser. And Di-tert-butyl malonate were charged in an amount ratio of 80 mol% and 20 mol%, respectively, and dipropylene glycol dimethyl ether (DPDM) was added to prepare the solid content to 65% by mass. Then, while stirring the solution, a methanol solution containing sodium methylate (28% by mass with respect to the total mass of the solution) was added dropwise by 1.0 part by mass, and then an outer bath was prepared so that the solution temperature became 52 ° C. The reaction was carried out at 52 ° C. for 7 hours or more to obtain a blocked polyisocyanate BP-1 having a solid content of 65% by mass. The average number of isocyanate functional groups of the blocked polyisocyanate BP-1 was ^3.9 , and the weight average molecular weight Mw was 6.21 × 103.

[Synthesis Example 2-3]
(Synthesis of polyisocyanate P-2)
A trifunctional polycaprolactone polyol derived from HDI: 100 parts by mass and trihydric alcohol and ε-caprolactone under a nitrogen stream in a four-necked flask equipped with a thermometer, stirring blade and reflux cooling tube. "Praccel 303" (trade name) manufactured by Daicel Chemical Co., Ltd., average number of hydroxyl functional groups: 3, number average molecular weight 300): 5.2 parts by mass was charged, and the temperature inside the reactor was maintained at 86 ° C. for 1 hour under stirring to make urethane. A chemical reaction was carried out. After that, the temperature inside the reactor was maintained at 62 ° C., an isocyanurate-forming catalyst tetramethylammonium capriate was added, and when the yield reached 51% by mass, phosphoric acid was added to terminate the reaction. After filtering the reaction solution, unreacted HDI was removed using a thin-film evaporator to obtain an isocyanurate-type polyisocyanate (hereinafter, may be referred to as "polyisocyanate P-2"). The NCO content of the obtained polyisocyanate P-2 was 18.9% by mass, the average number of isocyanate functional groups was 5.4, the number average molecular weight was 1200, and the weight ^average molecular weight Mw was 3.18 × 103. In addition, ¹ H-NMR analysis was performed on the obtained polyisocyanate P-2, and it was confirmed that an isocyanurate group was present.

[Synthesis Example 2-4]
(Synthesis of Block Polyisocyanate BP-2)
Diisopropyl malonic acid was added to 100 mol% of the isocyanate groups of the polyisocyanate P-2 obtained in Synthesis Example 2-3 under a nitrogen stream in a four-necked flask equipped with a thermometer, a stirring blade, and a reflux condenser. And di-tert-butyl malonic acid were charged in an amount ratio of 85 mol% and 15 mol%, respectively, and DPDM was added to prepare the solid content to 65% by mass. Then, while stirring the solution, a methanol solution containing sodium methylate (28% by mass with respect to the total mass of the solution) was added dropwise by 1.0 part by mass, and then an outer bath was prepared so that the solution temperature became 48 ° C. The reaction was carried out at 48 ° C. for 8 hours or more to obtain a blocked polyisocyanate BP-2 having a solid content of 65% by mass. The average number of isocyanate functional groups of the blocked polyisocyanate BP- ² was 5.4, and the weight average molecular weight Mw was 8.22 × 103.

[Synthesis Example 2-5]
(Synthesis of polyisocyanate P-3)
In a four-necked flask equipped with a thermometer, a stirring blade and a reflux condenser, HDI: 70 parts by mass, IPDI: 30 parts by mass, and trimethylolpropane (average hydroxyl group functional), which is a trihydric alcohol, under a nitrogen stream. The number of groups: 3 and the molecular weight: 134): 3.2 parts by mass were charged, and the temperature inside the reactor was maintained at 85 ° C. for 1.5 hours under stirring to carry out the urethanization reaction. After that, the temperature inside the reactor was maintained at 78 ° C., isocyanurate-forming catalyst tetramethylammonium capriate: 0.012 parts by mass was added, and when the yield reached 44% by mass, phosphoric acid was added to stop the reaction. After filtering the reaction solution, unreacted HDI and IPDI were removed using a thin film evaporator to obtain an isocyanurate-type polyisocyanate (hereinafter, may be referred to as "polyisocyanate P-3"). The NCO content of the obtained polyisocyanate P- ³ was 19.0% by mass, the average number of isocyanate groups was 5.5, the number average molecular weight was 1210, and the weight average molecular weight Mw was 2.95 × 103. In addition, ¹ H-NMR analysis was performed on the obtained polyisocyanate P-3, and it was confirmed that an isocyanurate group was present.

[Synthesis Example 2-6]
(Synthesis of Block Polyisocyanate BP-3)
Diisopropyl malonic acid was added to 100 mol% of the isocyanate groups of the polyisocyanate P-3 obtained in Synthesis Example 2-5 under a nitrogen stream in a four-necked flask equipped with a thermometer, a stirring blade, and a reflux condenser. And di-tert-butyl malonic acid were charged in an amount ratio of 83 mol% and 17 mol%, respectively, and DPDM was added to prepare the solid content to 65% by mass. Then, while stirring the solution, a methanol solution containing sodium methylate (28% by mass with respect to the total mass of the solution) was added dropwise by 1.0 part by mass, and then an outer bath was prepared so that the solution temperature became 52 ° C. The reaction was carried out at 52 ° C. for 8 hours or more to obtain a blocked polyisocyanate BP-3 having a solid content of 65% by mass. The average number of isocyanate functional groups of the blocked polyisocyanate BP- ³ was 5.5, and the weight average molecular weight Mw was 7.22 × 103.

[Synthesis Example 2-7]
(Synthesis of polyisocyanate P-4)
In a four-necked flask equipped with a thermometer, a stirring blade, and a reflux condenser, 100 parts by mass of hexamethylene diisocyanate (HDI) was charged under a nitrogen stream, the temperature inside the reactor was raised to 50 ° C., and then stirring was performed. While adding 8.0 parts by mass of trimethylol propane, the temperature inside the reactor was maintained at 67 ° C. for 5 hours, and then the reaction was stopped. After filtering the reaction solution, unreacted HDI was removed by a thin film distillation apparatus to obtain polyisocyanate P-4. The obtained polyisocyanate P-4 has an NCO content of 17.3% by mass, an average number of isocyanate functional groups of 3.5, a number average molecular weight Mn of 8.52 × 10 ² , and a weight average molecular weight Mw of 1.22 × 10. It was ³ . Further, ¹ H-NMR analysis and IR spectrum analysis were performed on the obtained polyisocyanate P-4, and it was confirmed that the urethane structure was present.

[Synthesis Example 2-8]
(Synthesis of Block Polyisocyanate BP-4)
Diisopropyl malonate with respect to 100 mol% of the isocyanate group of the polyisocyanate P-4 obtained in Synthesis Example 2-7 under a nitrogen stream in a four-necked flask equipped with a thermometer, a stirring blade, and a reflux condenser. And Di-tert-butyl malonate were charged in an amount ratio of 80 mol% and 20 mol%, respectively, and dipropylene glycol dimethyl ether (DPDM) was added to prepare the solid content to 65% by mass. Then, while stirring the solution, a methanol solution containing sodium methylate (28% by mass with respect to the total mass of the solution) was added dropwise by 1.0 part by mass, and then an outer bath was prepared so that the solution temperature became 53 ° C. The reaction was carried out at 53 ° C. for 7 hours or more to obtain a blocked polyisocyanate BP-4 having a solid content of 65% by mass. The average number of isocyanate functional groups of the blocked polyisocyanate BP-4 was ^3.5 , and the weight average molecular weight Mw was 3.25 × 103.

[Synthesis Example 2-9]
(Synthesis of Block Polyisocyanate BP-5)
Diisopropyl malonate with respect to 100 mol% of the isocyanate group of the polyisocyanate P-1 obtained in Synthesis Example 2-1 under a nitrogen stream in a four-necked flask equipped with a thermometer, a stirring blade, and a reflux condenser. And Di-tert-butyl malonate were charged in an amount ratio of 90 mol% and 10 mol%, respectively, and dipropylene glycol dimethyl ether (DPDM) was added to prepare the solid content to 65% by mass. Then, while stirring the solution, a methanol solution containing sodium methylate (28% by mass with respect to the total mass of the solution) was added dropwise by 1.0 part by mass, and then an outer bath was prepared so that the solution temperature became 52 ° C. The reaction was carried out at 52 ° C. for 7 hours or more to obtain a blocked polyisocyanate BP-5 having a solid content of 65% by mass. The average number of isocyanate functional groups of the blocked polyisocyanate BP- ⁵ was 3.9, and the weight average molecular weight Mw was 6.91 × 103.

<Manufacturing of adhesive composition>
[Examples 1 to 22 and Comparative Example 4]
(Manufacturing of Adhesive Compositions A-a1 to A-a22 and Ab4)
The type and amount of polyisocyanate added, and the amount of tert-butyl alcohol (tBu-OH) and ethyl acetate added to 100 parts by mass of the acrylic polymer are the amounts shown in Tables 1 to 3 or 6. As described above, tBu-OH and ethyl acetate were added to the polyisocyanate in this order and stirred, and then an acrylic polymer was added and stirred until uniform to obtain a pressure-sensitive adhesive composition having a solid content of 25% by mass.

[Examples 23 to 36]
(Manufacturing of Adhesive Compositions A-a23 to A-a36)
A solution previously mixed so that the type and amount of blocked polyisocyanate and the amount of ethyl acetate added are as shown in Tables 4 to 5 is added to 100 parts by mass of the acrylic polymer. Stirring until uniform was obtained to obtain a pressure-sensitive adhesive composition having a solid content of 25% by mass.

[Comparative Examples 1 to 3 and 5 to 6]
(Manufacturing of Adhesive Compositions Ab1 to Ab3 and Ab5 to Ab6)
Add a solution previously mixed so that the type and amount of polyisocyanate and the amount of ethyl acetate added are as shown in Table 6 with respect to 100 parts by mass of the acrylic polymer, until the mixture becomes uniform. The mixture was stirred to obtain a pressure-sensitive adhesive composition having a solid content of 25% by mass.

The pressure-sensitive adhesive compositions obtained in Examples and Comparative Examples were evaluated in various ways using the above methods. The results are shown in Tables 1 to 6 below.

From Tables 1 to 3, pressure-sensitive adhesive compositions A-a1 to A-a22 containing an acrylic polymer (a), a polyisocyanate as a cross-linking agent component (b1), and a secondary or tertiary alcohol (c) (Examples). In 1 to 22), the curability and pot life were excellent while maintaining good adhesiveness after heat curing.
Further, in comparison of the pressure-sensitive adhesive compositions A-a1 to A-a4 (Examples 1 to 4) having different contents of the secondary or tertiary alcohol (c), the content of the secondary or tertiary alcohol (c) is obtained. As the amount decreases, the adhesiveness after heat curing tends to be better, while as the content of the secondary or tertiary alcohol (c) increases, the gel fraction is higher (the curability is better). ), The gel fraction retention rate tended to be better.

From Tables 4 to 5, the pressure-sensitive adhesive compositions A-a23 to A-a36 (Examples 23 to 36) containing the acrylic polymer (a) and the blocking polyisocyanate as the cross-linking agent component (b2) have adhesiveness. It was excellent in curability and pot life while maintaining good condition.
Further, a comparison of the pressure-sensitive adhesive compositions A-a23 to A-a24 and A-a30 to A-a31 (Examples 23 to 24 and 30 to 31) having different contents of the blocked polyisocyanate, and the pressure-sensitive adhesive composition A-a25. Comparison of A-a26 (Examples 25 to 26), adhesive compositions A-a27 to A-a28 (Examples 27 to 28), and adhesive compositions A-a32 to A-a33 (Examples 32 to 32). In the comparison of 33), the higher the content of the blocked polyisocyanate, the better the curability, while the lower the content of the blocked polyisocyanate, the better the adhesiveness after heat curing. Was done.
Further, in the comparison of the pressure-sensitive adhesive compositions A-a28 and A-a34 (Examples 28 and 34) having different types of blocked polyisocyanates, those containing blocked polyisocyanates having a larger average isocyanate functional group have higher curability. On the other hand, those containing block polyisocyanates having a smaller weight average molecular weight Mw tended to be more excellent in adhesiveness after heat curing.
Further, a comparison of the pressure-sensitive adhesive compositions A-a23 and -a27 (Examples 23 and 27) in which the types of the acrylic polymers (a) are different, and the pressure-sensitive adhesive compositions A-a24 and A-a28 (Examples 24 and 28). In the comparison of the pressure-sensitive adhesive compositions A-a25 and A-a29 (Examples 25 and 29), the acrylic polymer having a higher content of the monomer unit having a carboxy group as a crosslinkable functional group (Examples 25 and 29). The one using a) tended to be more excellent in curability.
Further, in the comparison of the pressure-sensitive adhesive compositions A-a34 and A-a35 (Examples 34 and 35) in which the types of the acrylic polymer (a) are different, the one using the acrylic polymer a-4 is more adherent after heat curing. On the other hand, the one using the acrylic polymer a-8 tended to be more excellent in curability.

On the other hand, from Table 6, the pressure-sensitive adhesive compositions Ab1 to Ab3 containing the acrylic polymer (a) and the polyisocyanate as the cross-linking agent component (b1) but not the secondary or tertiary alcohol (c). And Ab5 to Ab6 (Comparative Examples 1 to 3 and 5 to 6) had good curability and adhesiveness after heat curing, but gelled during storage and had poor pot life.
Further, the acrylic polymer (a), the polyisocyanate as the cross-linking agent component (b1), and the secondary or tertiary alcohol (c) are contained, but the content of the secondary or tertiary alcohol (c) is the acrylic polymer ( a) In the pressure-sensitive adhesive composition Ab4 (Comparative Example 4), which is 1 part by mass with respect to 100 parts by mass, the curability and the stickiness after heat curing were good, but gelled during storage and potted. Life was bad.

According to the pressure-sensitive adhesive composition of the present embodiment, it is possible to provide a pressure-sensitive adhesive composition having excellent curability and pot life while maintaining good adhesiveness after heat-curing.

Claims (16)

Acrylic polymer (a) having a crosslinkable functional group and having a glass transition temperature Tg of −70 ° C. or higher and 0 ° C. or lower,
Crosslinking agent component (b1) containing aliphatic or alicyclic polyisocyanate,
Containing secondary or tertiary alcohol (c),
Or, with the acrylic polymer (a)
Containing a cross-linking agent component (b2) containing an aliphatic or alicyclic polyisocyanate and a blocked polyisocyanate derived from a blocking agent,
The content of the monomer unit having a crosslinkable functional group with respect to the total mass of the acrylic polymer (a) is 0.1% by mass or more and 20% by mass or less.
The content of the cross-linking agent component (b1) is 0.05 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the acrylic polymer (a).
The content of the secondary or tertiary alcohol (c) is 5 parts by mass or more and 300 parts by mass or less with respect to 100 parts by mass of the acrylic polymer (a).
A pressure-sensitive adhesive composition in which the content of the cross-linking agent component (b2) is 0.1 part by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the acrylic polymer (a). The pressure-sensitive adhesive composition according to claim 1, wherein the aliphatic or alicyclic polyisocyanate has an average number of isocyanate functional groups of 2 or more. The pressure-sensitive adhesive composition according to claim 1 or 2, wherein the secondary or tertiary alcohol (c) contains a tertiary alcohol. The blocking agent is at least one compound selected from the group consisting of an active methylene compound, an oxime compound, an amine compound, a pyrazole compound, and a triazole compound, according to any one of claims 1 to 3. The pressure-sensitive adhesive composition according to the above. The blocking agent is an active methylene compound and
The pressure-sensitive adhesive composition according to any one of claims 1 to 4, wherein the active methylene compound contains a malonic acid ester having a secondary alkyl group or a malonic acid ester having a tertiary alkyl group. The blocking agent is an active methylene compound and
The pressure-sensitive adhesive composition according to any one of claims 1 to 5, wherein the active methylene compound comprises a malonic acid ester having a secondary alkyl group and a malonic acid ester having a tertiary alkyl group. According to any one of claims 1 to 6, the weight average molecular weight Mw of the cross-linking agent component (b1) and the cross-linking agent component (b2) is 1.0 × 10 ³ or more and 1.0 × ¹⁰⁵ or less, respectively. The pressure-sensitive adhesive composition according to the description. One of claims 1 to 7, wherein the aliphatic or alicyclic polyisocyanate has at least one structure selected from the group consisting of a urethane structure, an allophanate structure, a biuret structure, a urea structure, and an isocyanurate structure. The pressure-sensitive adhesive composition according to. The adhesive according to any one of claims 1 to 8, wherein the acrylic polymer (a) contains at least one acrylic acid ester unit having an alkyl group having 1 or more and 20 or less carbon atoms at the end of the ester group. Agent composition. The pressure-sensitive adhesive composition according to any one of claims 1 to 9, wherein the crosslinkable functional group is one or more functional groups selected from the group consisting of a hydroxyl group, a carboxy group, and an epoxy group. The pressure-sensitive adhesive composition according to any one of claims 1 to 10, wherein the acrylic polymer (a) has a weight average molecular weight Mw of 3.0 × 105 or more and ^2.5 × ¹⁰⁶ or less. A cured product obtained by curing the pressure-sensitive adhesive composition according to any one of claims 1 to 11 by heat or light. With the base material
A pressure-sensitive adhesive layer is provided on the substrate.
A pressure-sensitive adhesive sheet in which the pressure-sensitive adhesive layer is a cured product of the pressure-sensitive adhesive composition according to any one of claims 1 to 11. The pressure-sensitive adhesive sheet according to claim 13, wherein the thickness of the pressure-sensitive adhesive layer is 0.1 μm or more and 1000 μm or less. A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer having a thickness of 45 μm, which is obtained by applying the pressure-sensitive adhesive composition on a stripped polyethylene terephthalate film having a thickness of 38 μm, drying at 130 ° C. for 3 minutes, and curing the pressure-sensitive adhesive composition, is formed at 23 ° C. and 50 ° C. Claimed that the gel fraction calculated by immersing in ethyl acetate at 23 ° C. for 1 week after storage in a% RH environment for 7 days and drying at 120 ° C. for 2 hours is 20% by mass or more and 98% by mass or less. The adhesive sheet according to 13 or 14. A pressure-sensitive adhesive sheet having a width of 20 mm and a length of 100 mm provided with a pressure-sensitive adhesive layer having a thickness of 45 μm obtained by applying the pressure-sensitive adhesive composition onto a polyethylene terephthalate film having a thickness of 25 μm and drying and curing the pressure-sensitive adhesive composition at 130 ° C. for 3 minutes. After storage for 7 days in a 23 ° C, 50% RH environment, a SUS304BA steel plate was used as an adherend, crimped once with a 2 kg roller, cured at 23 ° C for 30 minutes, and then measured at a speed of 23 ° C, 300 mm / min. The pressure-sensitive adhesive sheet according to any one of claims 13 to 15, wherein the 180-degree peel adhesive strength is 0.05 N / 20 mm or more and 40 N / 20 mm or less.