TWI649385B - Adhesive composition, adhesive and adhesive sheet - Google Patents

Abstract

The present invention provides an adhesive composition, an adhesive, and an adhesive sheet having excellent durability when applied to an optical member such as a polarizing plate. In order to solve the above-mentioned problems, an adhesive composition is provided which includes, as a monomer unit constituting a polymer, a (meth) acrylate polymer (A) containing a monomer having an alicyclic structure, and having an average weight Molecular weight is 900,000 to 3 million; bridging agent (B) and active energy ray curable component (C).

Description

Adhesive composition, adhesive and adhesive sheet

The present invention relates to an adhesive composition, an adhesive (a material for curing the adhesive composition) and an adhesive sheet, and more particularly to an adhesive composition suitable for use as an optical member such as a polarizing plate, Adhesives and adhesive sheets.

In recent years, in various electronic devices, a touch panel having both a display device and an input means has been used. The types of touch panels are mainly resistive, capacitive, optical, and ultrasonic. Resistive touch panels include analog data resistive and matrix resistive. Capacitive touch panels are available in surface and projection types.

Recently, the touch panels of mobile electronic devices such as smartphones and tablet terminals have attracted attention. Projection-type capacitive touch panels are mostly used. As a projection type capacitive touch panel of the above-mentioned mobile electronic device, for example, research has proposed that a liquid crystal display device (LCD), an adhesive layer, and a transparent conductive film (tin-doped indium oxide: ITO) are sequentially stacked from the bottom to the top. ), A glass substrate, a transparent conductive film (ITO), and a touch panel with a protective layer such as tempered glass.

As the optical member constituting the liquid crystal display device, a liquid crystal module is generally used. In a liquid crystal module, an alignment layer of two transparent electrode substrates forming an alignment layer is generally used as an inner side, and a spacer is arranged to form a predetermined interval. The periphery is sealed, and a liquid crystal material is held between the two transparent electrode substrates. s component. Generally, the outer surface of two transparent electrode substrates in a liquid crystal module On the side, the polarizing plates are adhered with an adhesive, respectively.

As an adhesive used for a touch panel, the adhesive shown in patent document 1, for example is known. This adhesive contains, as a monomer unit, 100 parts by weight of an alkyl (meth) acrylate having an alkyl group having 4 to 14 carbon atoms, and contains 0.2 to 20 parts by weight of a carboxyl group-containing monomer as a monomer unit. (Meth) propylene polymer obtained by copolymerizing the components, and as a bridging agent with respect to 100 parts by weight of the (meth) propylene polymer, containing 0.02 to 2 parts by weight of a peroxide and epoxy Cross-linking agent 0.005 parts by weight to 5 parts by weight.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2009-242786

In the touch panel as described above, a polarizing plate using a polycycloolefin-based protective film has recently been used. In addition, with the reduction in thickness of mobile electronic devices in recent years, the polarizing plate is also becoming thinner. However, polycycloolefin-based materials lack adhesion to the adhesive, and the thin polarizer has a high shrinkage rate. Therefore, conventional adhesives such as Patent Document 1 have low durability. Due to aging or under high temperature conditions, Under the hot and humid conditions, there is a problem that floating and peeling easily occur.

The present invention has been made in view of such a situation, and an object thereof is to provide an adhesive composition, an adhesive, and an adhesive sheet that are also excellent in durability when applied to an optical member such as a polarizing plate.

To achieve the above object, first, the present invention provides an adhesive A composition containing (meth) acrylate polymer (A) having a weight average molecular weight of 900,000 to 3,000,000 as a monomer unit constituting the polymer, containing a monomer having an alicyclic structure. Body; bridging agent (B); and active energy ray-curable component (C) (Invention 1).

When the adhesive composition according to the above invention (Invention 1) is cured, the (meth) acrylate polymer (A) is bridged by a bridging agent (B) to form a first three-dimensional network structure, and at the same time, a plurality of active energies The linear curable components (C) are combined with each other to form a second three-dimensional network structure. It is speculated that the first three-dimensional network structure and the second three-dimensional network structure are intertwined with each other to form an overall three-dimensional network structure. The adhesive obtained by curing the above-mentioned adhesive composition interacts with the above-mentioned structure and the alicyclic structure of the (meth) acrylate polymer (A), and is particularly useful in optical members such as polarizing plates, and the like. When a polycycloolefin-based optical member or a transparent conductive film is used as an adherend, durability is also excellent.

In the above invention (Invention 1), the (meth) acrylate polymer (A), as a monomer unit constituting the polymer, preferably contains 0.1 to 30% by mass of a monomer having the alicyclic structure.体 (Invention 2).

In the above invention (Invention 1, Invention 2), the alicyclic structure preferably contains a cyclohexyl skeleton, a dicyclopentadiene skeleton, an adamantane skeleton, or an isobornyl skeleton (Invention 3).

In the above invention (Invention 1 to Invention 3), the (meth) acrylate polymer (A), as a monomer unit constituting the polymer, more preferably contains 0.1 to 10% by mass of a monomer having a hydroxyl group.体 (Invention 4).

In the above invention (Invention 1 to Invention 4), it is preferable that the (meth) acrylate polymer (A) as a monomer unit constituting the polymer is substantially It does not contain a monomer having a carboxyl group (Invention 5).

In the above invention (Invention 1 to Invention 5), the bridging agent (B) is preferably an isocyanate bridging agent (Invention 6).

In the above invention (Invention 1 to Invention 6), the active energy ray-curable component (C) is preferably a polyfunctional acrylate monomer having a molecular weight of less than 1,000 (Invention 7).

In the said invention (invention 7), it is preferable that the said polyfunctional acrylate monomer has a cyclic structure (invention 8).

In the said invention (invention 1 to invention 8), content of the said active-energy-ray-curable component (C) in the said adhesive composition is 100 mass parts with respect to the said (meth) acrylate polymer (A) It is preferably 1 to 30 parts by mass (Invention 9).

In the said invention (invention 1 to invention 9), it is more preferable to contain a photoinitiator (D) (invention 10).

Secondly, the present invention provides an adhesive (invention 11) for curing the above-mentioned adhesive composition (invention 1 to invention 10) by irradiation with active energy rays.

Third, the present invention provides an adhesive sheet, which is an adhesive sheet having a substrate and an adhesive layer, and the adhesive layer is composed of the adhesive (Invention 11) (Invention 12).

In the said invention (invention 12), it is preferable that the said base material is an optical member (invention 13).

In the said invention (invention 13), it is preferable that the said optical member is a polarizing plate (invention 14).

In the above invention (Invention 13, Invention 14), the optical member preferably has a polycycloolefin-based film (Invention 15). In addition, the above-mentioned "having a polycycloolefin-based film" includes the concept of "consisting only of a polycycloolefin-based film".

Fourth, the present invention provides an adhesive sheet, which is characterized in that it includes two release sheets and an adhesive layer holding the release sheet so that the release surfaces of the two release sheets are in contact with each other, and the adhesive layer is It consists of the said adhesive agent (invention 11) (invention 16).

When the adhesive composition according to the present invention contains the components (A) to (C), the obtained adhesive has high durability and is suitable for use in optical members such as polarizing plates.

1A, 1B ‧‧‧ Adhesive Sheet

11‧‧‧Adhesive layer

12, 12a, 12b ‧‧‧ peeling sheet

13‧‧‧ substrate

FIG. 1 is a cross-sectional view of an adhesive sheet according to a first embodiment of the present invention.

Fig. 2 is a sectional view of an adhesive sheet according to a second embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described.

[Adhesive composition]

The adhesive composition according to this embodiment (hereinafter referred to as "adhesive composition P") contains, as a monomer unit constituting a polymer, a (meth) acrylate polymer (A) and a bridging agent ( B). The active energy ray-curable component (C) preferably further contains a photopolymerization initiator (D) and / or a silane coupling agent (E). The weight average of the (meth) acrylate polymer (A) The molecular weight is 900,000 to 3 million, and it contains a monomer having an alicyclic structure (containing an alicyclic structure monomer). In addition, in this specification, The (meth) acrylate refers to both acrylate and methacrylate. The same applies to other similar terms. In addition, the term "copolymer" is also included in "polymer".

When the adhesive composition P is cured, the (meth) acrylate polymer (A) is bridged by the bridging agent (B) to form a first three-dimensional network structure. On the other hand, a plurality of active energy ray-curable components (C) are combined with each other to form a second three-dimensional network structure. It is presumed that the first three-dimensional network structure and the second three-dimensional network structure are intertwined with each other to form a whole three-dimensional network structure (hereinafter referred to as "structure X").

The adhesive obtained by curing the adhesive composition P has an alicyclic structure function in the structure X and the (meth) acrylate polymer (A), and is particularly useful in optical members such as polarizing plates, and the like. When a polycycloolefin-based optical member (for example, an optical member composed of a polycycloolefin-based film or an optical member having a part of the polycycloolefin-based film) or a transparent conductive film is used as an adherend, durability is also excellent.

(1) (meth) acrylate polymer (A)

The (meth) acrylate polymer (A) contains a monomer having an alicyclic structure as a monomer unit constituting the polymer. Thereby, the obtained adhesive becomes the adhesive excellent in durability as mentioned above. It is considered that this effect is due to the relatively strong affinity and interaction between the alicyclic structure and the optical member or the transparent conductive film, and the increase in adhesion and the like.

The carbon atom ring of the alicyclic structure may be a carbon atom ring of a saturated structure or a carbon atom ring containing an unsaturated bond. Moreover, the alicyclic structure may be a monocyclic alicyclic structure, or a bicyclic, tricyclic, or other polycyclic alicyclic structure. The number of carbon atoms in the alicyclic structure is preferably 5 to 20, and particularly preferably It is 6 to 15, and more preferably 7 to 12.

Examples of the alicyclic structure include a cyclohexyl skeleton, a dicyclopentadiene skeleton, an adamantane skeleton, an isobornyl skeleton, a cycloalkane skeleton (cycloheptane skeleton, cyclooctane skeleton, cyclononane skeleton, cyclodecane). Skeleton, cycloundecane skeleton, cyclododecane skeleton, etc.), cyclic olefin skeleton (cycloheptene skeleton, cyclooctene skeleton, etc.), norbornene skeleton, norbornadiene skeleton, polycyclic skeleton (cubane Skeleton, pentacyclodecane skeleton, aventane skeleton, etc.), and alicyclic structures such as spirocyclic skeleton, among which a cyclohexyl skeleton, a dicyclopentadiene skeleton, and an adamantane skeleton which exhibit a more excellent durability upward effect are preferred Or the alicyclic structure of the isobornyl skeleton.

As the alicyclic structure-containing monomer, a (meth) acrylate monomer containing the above-mentioned skeleton is preferable, and specifically, cyclohexyl (meth) acrylate and dicyclopentyl (meth) acrylate are mentioned. , Adamantyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, etc., among them, preferred Cyclohexyl (meth) acrylate, dicyclopentyl (meth) acrylate, adamantyl (meth) acrylate, or isobornyl (meth) acrylate exhibiting more excellent durability-improving effects. These may be used alone or in combination of two or more.

The (meth) acrylate polymer (A), as a monomer unit constituting the polymer, preferably contains 0.1 to 30% by mass of the above-mentioned alicyclic structure-containing monomer, and particularly preferably contains 0.2% by mass to 25 mass%, more preferably 0.5 mass% to 13 mass%. When the content of the alicyclic structure-containing monomer is less than 0.1% by mass, it is difficult to obtain the aforementioned effect of improving durability. If the content of the alicyclic structure-containing monomer exceeds 30% by mass, it is regarded as In optical applications, preferable adhesiveness may not be obtained.

The (meth) acrylic acid ester polymer (A), as the monomer unit constituting the polymer, in addition to the alicyclic structure-containing monomer described above, it is also preferable that the Alkyl) acrylate is particularly preferably contained as a main component.

The (meth) acrylic acid ester polymer (A), as a monomer unit constituting the polymer, can exhibit preferable adhesion by an alkyl (meth) acrylic acid ester having 1 to 20 carbon atoms in the alkyl group. Sex. Examples of the alkyl (meth) acrylate having 1 to 20 carbon atoms in the alkyl group include methyl (meth) acrylate, ethyl (meth) acrylate, and propyl (meth) acrylate. Ester, n-butyl (meth) acrylate, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isomethacrylate Octyl ester, n-decyl (meth) acrylate, n-dodecyl (meth) acrylate, myristyl (meth) acrylate, cetyl (meth) acrylate, (methyl) ) Acrylic stearyl and the like. Among them, (meth) acrylates having 1 to 8 carbon atoms in the alkyl group are preferable from the viewpoint of further improving the adhesiveness, and methyl (meth) acrylate and n-butyl (meth) acrylate are particularly preferable. These may be used alone or in combination of two or more.

The (meth) acrylic acid ester polymer (A) is preferably a (meth) acrylic acid alkyl group having 1 to 20 carbon atoms having 20 to 99.8% by mass of an alkyl group as a monomer unit constituting the polymer. The ester particularly preferably contains 50% to 99.5% by mass, and more preferably 60% to 99% by mass.

The (meth) acrylate polymer (A) preferably contains a monomer having a hydroxyl group (a hydroxyl-containing monomer) as a monomer unit constituting the polymer. The reactive functional group of the hydroxyl group and the bridging agent (B), especially the isocyanate group of the isocyanate-based bridging agent, has high reactivity. Due to these reactions, the (meth) acrylate polymer (A) is effective due to the bridging agent (B). Ground bridge, forming a good bridge structure. Thereby, the obtained adhesive is more excellent in durability.

Examples of the hydroxyl-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and (methyl) ) 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, etc. From the viewpoint of the reactivity of the hydroxy bridging agent (B) in the (meth) acrylate polymer (A) and the copolymerizability with other monomers, 2-hydroxyethyl (meth) acrylate is preferred. These may be used alone or in combination of two or more.

The (meth) acrylate polymer (A), as a monomer unit constituting the polymer, preferably contains 0.1 to 10% by mass of a hydroxyl group-containing monomer, and particularly preferably contains 0.2 to 8% by mass. Further, It is preferably contained in an amount of 0.3 to 5% by mass. When the content of the hydroxyl group-containing monomer is within the above range, the formed bridging structure is good, and the obtained adhesive has more excellent durability. When the content of the hydroxyl-containing monomer is less than 0.1% by mass, the number of bridge points is too small, and it is difficult to obtain the effect of improving durability. On the other hand, if the content of the hydroxyl-containing monomer exceeds 10% by mass, there will be too many bridging points, and the resulting adhesive may not be soft and the stress relaxation may be reduced.

The (meth) acrylate polymer (A), as a monomer unit constituting the polymer, preferably does not substantially contain a monomer having a carboxyl group (a carboxyl group-containing monomer). By substantially not containing a monomer having a carboxyl group having an acid component, it is possible to suppress Defects caused by the acid due to the adhered object of the obtained adhesive can be suppressed by the acid even in the case of a transparent conductive film or a metal film, for example. In particular, when the object to be attached is a transparent conductive film, it is possible to suppress the transparent conductive film from being rotten or to change the resistance value of the transparent conductive film. In addition, like the silane coupling agent (E), a polymer not affected by an acid also functions effectively by using a mercapto group-containing silane coupling agent described later. In addition, by not substantially containing a monomer having a carboxyl group, it is possible to prevent the carboxyl group from hindering the reaction between the hydroxyl group of the hydroxyl-containing monomer and the bridging agent (B), and in particular, with an isocyanate-based bridging agent.

The (meth) acrylate polymer (A) may contain other monomers in addition to the above-mentioned monomers as necessary. The other monomer may be a monomer having a reactive functional group other than a hydroxyl group (a reactive functional group-containing monomer), or may be a non-reactive monomer.

Examples of the reactive functional group-containing monomer include a monomer having an amino group (amino-containing monomer) and the like. Examples of the amino group-containing monomer include aminoethyl (meth) acrylate and n-butylaminoethyl (meth) acrylate. These may be used alone or in combination of two or more.

Examples of the non-reactive monomer include methoxymethyl (meth) acrylate, methoxyethyl (meth) acrylate, ethoxymethyl (meth) acrylate, and (meth) (Meth) acrylates, such as ethoxyethyl acrylate, alkoxyalkyl (meth) acrylates, phenyl (meth) acrylates, etc., (meth) acrylates having aromatic rings, acrylamide, Non-bridged acrylamide such as methacrylamide, N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, etc. Non-bridged tertiary amino (meth) acrylate, vinyl acetate, styrene, etc. These can be used alone or in combination Use more than two.

The polymerization method of the (meth) acrylate polymer (A) may be a random copolymer or a block copolymer.

The weight average molecular weight of the (meth) acrylate polymer (A) is 900,000 to 3 million, preferably 1 to 2.5 million, and particularly preferably 1.1 to 2 million. In addition, the weight average molecular weight in this specification is a polystyrene conversion value measured by the gel permeation chromatography (GPC) method.

When the weight average molecular weight of the (meth) acrylate polymer (A) is less than 900,000, the durability of the obtained adhesive is poor. When the weight average molecular weight of the (meth) acrylate polymer (A) exceeds 3 million, the adhesive force of the obtained adhesive is reduced.

In addition, in the adhesive composition P, a (meth) acrylate polymer (A) may be used individually by 1 type, and may be used in combination of 2 or more type. Further, the adhesive composition P may further contain a (meth) acrylate polymer that does not contain the alicyclic structure-containing monomer as a constituent monomer unit.

(2) bridging agent (B)

The bridging agent (B) may be a reactive bridging agent with respect to a reactive functional group (such as a hydroxyl group and an amino group) of the (meth) acrylate polymer (A), and examples thereof include isocyanates. Bridging agent, isocyanate bridging agent, epoxy bridging agent, amine bridging agent, melamine bridging agent, aziridine bridging agent, hydrazine bridging agent, aldehyde bridging agent, oxazoline bridging agent, metal alcohol Salt bridging agent, metal chelate bridging agent, metal salt bridging agent, ammonium salt bridging agent, etc. Among them, when the (meth) acrylate polymer (A) has a hydroxyl group, the isocyanate-based bridging agent has the advantage of being excellent in reactivity with the hydroxyl group. bridge The agent (B) may be used singly or in combination of two or more kinds.

The isocyanate-based bridging agent is a bridging agent containing at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as methylenephenyl diisocyanate, diphenylmethane diisocyanate, and xylene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate; and isophor Alicyclic polyisocyanates, such as keto diisocyanate, hydrogenated diphenylmethane diisocyanate, etc., and these bisureton bodies, isocyanate bodies, and further include ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, Additives such as castor oil and the like as reactants with low-molecular active hydrogen compounds. Among these, from the viewpoint of reactivity with the hydroxyl group of the (meth) acrylate polymer (A), trimethylolpropane-modified aromatic polyisocyanate is preferred, and trimethylolpropane-modified xylene is particularly preferred. Isocyanate and trimethylolpropane modified methylenediphenyl diisocyanate.

The content of the bridging agent (B) in the adhesive composition P is preferably from 0.05 to 3 parts by mass, and particularly preferably from 0.08 to 1.5 parts by mass based on 100 parts by mass of the (meth) acrylate polymer (A). The mass part is more preferably 0.1 part by mass to 1 part by mass. When the content of the bridging agent (B) is 0.05 parts by mass or more, the effect of improving the durability by the bridging agent (B) can be obtained. When the content of the bridging agent (B) exceeds 3 parts by mass, the degree of bridging is excessive, and the adhesive force of the obtained adhesive may be reduced.

(3) Active energy ray curable component (C)

The active energy ray-curable component (C) is not particularly limited as long as it is a component that does not prevent the effects of the present invention and is cured by irradiation of the active energy ray, and may be a monomer, an oligomer, or a polymer. Either one, or for them mixture. Among them, preferred are polyfunctional acrylate monomers having a molecular weight of less than 1,000 and having excellent compatibility with the (meth) acrylate polymer (A) and the like.

Examples of the polyfunctional acrylate monomer having a molecular weight of less than 1,000 include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, and neopentyl Alcohol di (meth) acrylate, polyethylene glycol di (meth) acrylate, neopentyl glycol adipate di (meth) acrylate, hydroxypivalic acid neopentyl glycol di (meth) Acrylate, dicyclopentyl di (meth) acrylate, caprolactone-modified dicyclopentenyl di (meth) acrylate, ethylene oxide-modified phosphate di (meth) acrylate, di ( 2-functional types such as propylene ethoxyethyl) isocyanate, allyl cyclohexyl di (meth) acrylate; trimethylolpropane tri (meth) acrylate, dipentaerythritol tri (meth) acrylate , Propionic acid-modified dipentaerythritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, propylene oxide modified trimethylolpropane tri (meth) acrylate, tris (propyleneoxyethyl) ) Trifunctional type such as isocyanate; 4-functional type such as diglycerol tetra (meth) acrylate, pentaerythritol tetra (meth) acrylate; etc .; Propionic acid modified dipentaerythritol (Meth) acrylate functional type 5; dipentaerythritol hexa (meth) acrylate, caprolactone-modified dipentaerythritol hexa (meth) acrylate and hexafunctional type. These may be used alone or in combination of two or more.

Among the above-mentioned polyfunctional acrylate monomers, a polyfunctional acrylate monomer having a cyclic structure in the skeleton is more preferable because it has superior durability. The cyclic structure may be a carbocyclic structure or a heterocyclic structure, and may be a monocyclic structure or a polycyclic structure. Examples of such a polyfunctional acrylate-based monomer include a polyfunctional acrylic having an isocyanate structure, such as bis (acryloxyethyl) isocyanate and tris (acryloxyethyl) isocyanate. Acrylate monomers, dimethylol dicyclopentane diacrylate, ethylene oxide modified hexahydrophthalic acid diacrylate, tricyclic dimethanol acrylate, adamantane diacrylate, and the like.

As the active energy ray-curable component (C), an active energy ray-curable acrylate-based oligomer may be used. The acrylate oligomer preferably has a weight average molecular weight of 50,000 or less. Examples of such acrylate-based oligomers include polyester acrylates, epoxy acrylates, urethane acrylates, polyether acrylates, polybutadiene acrylates, Silicone acrylates, etc.

Here, the polyester acrylate type oligomer can be obtained by, for example, using (meth) acrylic acid, by polycondensing a polycarboxylic acid and a polyhydric alcohol, and obtaining hydroxyl groups and esters of the polyester oligomer having hydroxyl groups at both ends. Alternatively, it can be obtained by esterifying a hydroxy group at the terminal of an oligomer obtained by oxidizing an alkylene with a polycarboxylic acid using (meth) acrylic acid. The epoxy acrylate oligomer can be reacted with, for example, esterification of (meth) acrylic acid on the ethylene oxide ring of a relatively low molecular weight bisphenol epoxy resin or novolac epoxy resin. And get. In addition, a carboxy-modified epoxy acrylate oligomer obtained by partially modifying the epoxy acrylate-based oligomer with a dibasic carboxylic anhydride may also be used. The urethane acrylate oligomer can be obtained by, for example, esterifying a urethane oligomer obtained by reacting a polyether polyol or polyester polyol with a polyisocyanate with (meth) acrylic acid. get. The polyol acrylate oligomer can be obtained by esterifying a hydroxyl group of a polyether polyol with (meth) acrylic acid.

The weight average molecular weight of the acrylate oligomer is preferably 50,000 or less, particularly preferably 500 to 50,000, and even more preferably 3,000. ~ 40,000. These acrylate oligomers may be used singly or in combination of two or more kinds.

In addition, as the active energy ray-curable component (C), an adduct acrylate polymer obtained by introducing a group having a (meth) acrylfluorenyl group into a side chain may be used. Such an adduct acrylate polymer can have a copolymer with a (meth) acrylfluorene group and a bridging functional group by using a copolymer of (meth) acrylate and a monomer having a bridging functional group in the molecule. A compound of a reactive group is obtained by reacting with a part of the bridging functional group of the copolymer.

The (meth) acrylate is preferably an alkyl (meth) acrylate containing 1 to 20 carbon atoms in the alkyl group, and examples thereof include methyl (meth) acrylate and ethyl (meth) acrylate Ester, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, (meth) ) 2-ethylhexyl acrylate, isooctyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, myristyl (meth) acrylate, ( Cetyl (meth) acrylate, stearyl (meth) acrylate, and the like. These may be used alone or in combination of two or more.

The monomer having a bridging functional group in the molecule preferably contains, as a functional group, at least one selected from the group consisting of a hydroxyl group, a carboxyl group, an amino group, and an amido group. Examples of the monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and (meth) acrylic acid 2 -Hydroxyalkyl (meth) acrylates such as hydroxybutyl ester, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate; acrylamide, methacrylamide , N-methacrylamide, N-methacrylamine Acrylamines such as amines, N-methylol acrylamide, N-methylol acrylamide; monomethylaminoethyl (meth) acrylate, monoethylamino (meth) acrylate (Meth) acrylic acid monoalkylaminoalkyl esters such as ethyl ester, monomethylaminopropyl (meth) acrylate, monoethylaminopropyl (meth) acrylate; acrylic acid, methacrylic acid, Ethylene unsaturated carboxylic acids such as crotonic acid, maleic acid, itaconic acid, and citraconic acid. These monomers may be used alone or in combination of two or more.

As the compound having a group that reacts with a (meth) acrylfluorenyl group and a bridging functional group, for example, 2-methacrylfluorenyloxyethyl isocyanate and methacrylic acid 2- (0- [1 '-Methylpropaneamino] carboxyamino) ethyl, 2-[(3,5-dimethylpyrazole) carbonylamino] ethyl methacrylate, 1,1- (bispropenyloxymethyl) Ethyl isocyanate, 2-propenyloxyethyl isocyanate, 2-propenyloxyethyl succinate, 2-propenyloxyethylhexahydrophthalimide, imine, ω-carboxy-polycaprolactone mono Acrylate, phthalic acid monohydroxyethyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, and the like. These compounds may be used alone or in combination of two or more.

The weight average molecular weight of the additive acrylate polymer is preferably about 300,000 to 2 million, and particularly preferably 500,000 to 850,000.

The active energy ray-curable component (C) may be selected from one of the above-mentioned multifunctional acrylate monomers, acrylate oligomers, and adduct acrylate polymers, or two or more of them may be used. They can be used in combination, and can also be used in combination with other active energy ray-curable components.

Of the active energy ray-curable component (C) in the adhesive composition P The content is preferably 1 to 30 parts by mass, more preferably 2 to 20 parts by mass, and still more preferably 3 to 9 parts by mass based on 100 parts by mass of the (meth) acrylate polymer (A). Serving. The adhesive obtained from the adhesive composition P containing the active energy ray-curable component (C) in this range is presumably an adhesive that forms the structure X well.

(4) Photopolymerization initiator (D)

When using ultraviolet rays as an active energy ray irradiated to the adhesive composition P, it is preferable that the adhesive composition P further contains a photopolymerization initiator (D). By containing the photopolymerization initiator (D) as described above, the active energy ray-curable component (C) can be effectively cured, and the polymerization curing time and the amount of active energy ray irradiation can be reduced.

Examples of such a photopolymerization initiator (D) include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, Benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylbenzene Ethyl ketone, 2-hydroxy-2-methyl-1-phenylpropane-1-one, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] 2-morpholine-propane-1-one, 4- (2-hydroxyethoxy) phenyl-2- (hydroxy-2-propyl) one, benzophenone, P-phenylbenzophenone , 4,4'-diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, 2 -Methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyldimethylketal Ketone, acetophenone dimethyl ketal, P-dimethylaminobenzoate, oligo [2-hydroxy-2-methyl-1 [4- (1-methylvinyl) benzene] acetone], 2 , 4,6-trimethylbenzylidene-diphenyl-phosphine oxide and the like. These may be used alone or in combination of two or more.

The photopolymerization initiator (D) is preferably 2 to 15 parts by mass, and particularly preferably 5 to 12 parts by mass with respect to 100 parts by mass of the active energy ray-curable component (C). use.

(5) Silane coupling agent (E)

The adhesive composition P preferably contains a silane coupling agent (E). By including the silane coupling agent (E), the durability of the adhesive obtained from the adhesive composition P is more excellent.

As the silane coupling agent (E), for example, a silane coupling agent containing a (meth) acrylfluorenyl group, an epoxy group, an amino group, or a mercapto group as a functional group that reacts with an organic material can be preferably used. Among these, the adhesive composition P is particularly preferably a silane coupling agent containing a mercapto group as a functional group that reacts with an organic material (hereinafter referred to as a "mercaptosilane-containing coupling agent").

The above-mentioned adhesive composition P containing a mercaptosilane coupling agent is bridged, and the mercapto group containing the mercaptosilane coupling agent is reacted with a reactive functional group of the bridging agent (B). In particular, when the bridging agent (B) is an isocyanate-based bridging agent, a mercapto group containing a mercaptosilane coupling agent may easily form a thiourethane bond with the isocyanate group of the isocyanate-based bridging agent. On the other hand, the other reactive functional groups of the bridging agent (B) (isocyanate groups of the isocyanate-based bridging agent) react with the reactive functional groups (such as a hydroxyl group and an amino group) of the (meth) acrylate polymer (A). The (meth) acrylate polymer (A) is bridged to form a three-dimensional network structure. In addition, the alkoxysilyl group containing a mercaptosilane coupling agent is kept at a suitable distance from the (bridged) (meth) acrylate polymer (A), and is suspended from (meth) acrylic acid. Shape on the ester polymer (A). As a result, an excellent coupling effect is exhibited, and the obtained adhesive has excellent adhesiveness, and becomes an adhesive with more excellent durability even under high temperature conditions or wet heat conditions.

When the bridging agent (B) is an isocyanate-based bridging agent, the mercapto group contained in the mercaptosilane coupling agent is easily reacted with the isocyanate group of the isocyanate-based bridging agent, so the (meth) acrylate polymer (A) Even if it is a reactive functional group that is difficult to function in a general silane coupling agent (the (meth) acrylate polymer (A) may not contain a carboxyl group as a reactive functional group)), Coupling effect of mercaptosilane coupling agent.

The mercaptosilane-containing coupling agent is an organosilicon compound having at least one mercapto group and at least one alkoxysilyl group in the molecule. The organic silicon compound has good compatibility with the adhesive component and has light transparency. Be transparent.

Specific examples of the mercapto-containing silane coupling agent include 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyldimethoxymethylsilane, and the like. Mercapto-containing low-molecular-weight silane coupling agent; 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyldimethoxymethylsilane, etc. Copolycondensates of silane compounds and thiol-containing oligomers, such as methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane, and other alkyl-containing silane compounds Polymer type silane coupling agent, etc. Among these, from the viewpoint of improving durability, a mercapto-containing oligomeric silane coupling agent is preferred, a mercapto-containing silane compound and an alkylsilane compound-containing copolycondensate are particularly preferred, and 3-mercaptopropyl is more preferred. Trimethoxysilane and methyltriethyl Copolycondensates of oxysilanes. These may be used alone or in combination of two or more.

The mercapto-containing silane coupling agent is preferably an oligomer. In the thiol-containing silane coupling agent of the above oligomer, the thiol equivalent in the oligomer is preferably 100 g / mol to 1000 g / mol, particularly preferably 200 g / mol to 900 g / mol, and more preferably 300 g / mol to 700 g / mol. mol. If the mercapto equivalent is less than 100 g / mol, the effect of improving durability may be reduced. When the mercapto equivalent is more than 1000 g / mol, there is a possibility that a decrease in adhesive strength or poor peeling may occur.

The adhesive composition P also preferably contains a silane coupling agent containing an epoxy group as a functional group that reacts with an organic material. Examples of the epoxy group-containing silane coupling agent include glycidylpropyltrimethoxysilane, triethoxysilane glycidyl ester, triisopropyloxysilane, glycidyl tributoxysilane, and glycidyl trisilane. Chlorosilane, dimethoxy-chloro-glycidyloxysilane, glycidyl dichlorooxysilane, glycidyl chlorodiethoxysilane, glycidyl dichloroethoxysilane, glycidyl tribromosilane, 3-epoxy Propoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltributoxy Silane, 3-glycidoxypropyltrimethylchlorosilane, 3-glycidoxypropyldimethoxymethylsilane chloride, 3-glycidyloxypropyldimethylmethoxysilane , 3-glycidyloxypropyldiethoxysilane, 3-glycidoxypropyldichlorosilane, 3-glycidyloxytribromosilane, 2- (3,4-epoxycyclohexyl) ethyl Trimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltri-n-propoxysilane, 2- ( 3,4-epoxy ring Yl) ethyl - tributoxyethyl Silane like. These can be used singly or in combination. Use.

The content of the silane coupling agent (E) in the adhesive composition P is preferably 0.01 to 5 parts by mass, and particularly preferably 0.02 parts by mass relative to 100 parts by mass of the (meth) acrylate polymer (A). Parts to 3 parts by mass, and more preferably 0.05 parts by mass to 2 parts by mass. When the content of the silane coupling agent (E) is less than 0.01 parts by mass, it is difficult to obtain the effect by the silane coupling agent (E). On the other hand, when the content of the silane coupling agent (E) exceeds 5 parts by mass, there may be a case where the adhesive force is extremely reduced or the cohesive force is insufficient.

(6) Various additives

The adhesive composition P may be added with various additives commonly used in acrylic adhesives, such as an antistatic agent, an adhesion-imparting agent, an oxidation inhibitor, an ultraviolet absorber, a light stabilizer, a softener, and the like, as needed. Fillers, refractive index modifiers, etc.

Examples of the antistatic agent include ionic liquids, ionic solids, anionic surfactants, sulfonium metal salts, cationic surfactants, and nonionic surfactants. Among them, ionic liquids and ionic surfactants are preferably used. At least one selected from the group consisting of a solid solid and a rhenium metal salt.

As the ionic liquid and the ionic solid, a nitrogen-containing onium salt, a sulfur-containing xanthium salt, a phosphorus-containing onium salt, and the like are preferable. In addition, the phosphonium metal salt is preferably a lithium salt, a potassium salt, or the like. These may be used alone or in combination of two or more.

The content of the antistatic agent in the adhesive composition P is preferably 0.5% to 8% by mass, and particularly preferably 1% to 5% by mass. When the content of the antistatic agent is within the above range, the balance between the antistatic property and the durability of the adhesive becomes good.

[Manufacturing method of adhesive composition]

The adhesive composition P can be produced by (meth) acrylate polymer (A), and the obtained (meth) acrylate polymer (A), bridging agent (B), and active energy ray-curable component (C ) Are mixed, and at the same time, if necessary, a photopolymerization initiator (D), a silane coupling agent (E) additive, and the like are added to produce them.

The (meth) acrylate polymer (A) can be produced by polymerizing monomers (in the case of a copolymer, a mixture of monomers) constituting a polymer by a usual radical polymerization method. The polymerization of the (meth) acrylate polymer (A) can be performed by a solution polymerization method or the like using a polymerization initiator as necessary. Examples of the polymerization solvent include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, and methyl ethyl ketone, and two or more of them may be used in combination.

Examples of the polymerization initiator include an azo compound, an organic peroxide, and the like, and two or more of them may be used simultaneously. Examples of the azo compound include 2,2'-azobisisobutyronitrile, 2,2'-azobis (2-methylbutyronitrile), and 1,1'-azobis (cyclohexane). 1-nitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2,4-dimethyl-4-methoxyvaleronitrile) , Dimethyl 2,2'-azobis (2-methylpropionate), 4,4'-azobis (4-cyanovaleric acid), 2,2'-azobis (2-methylpropionate) Hydroxymethylpropionitrile), 2,2'-azobis [2- (2-imidazolin-2-yl) propane] and the like.

Examples of the organic peroxide include benzamidine peroxide, tert-butyl peroxybenzoate, cumene hydrogen peroxide, diisopropylperoxydicarbonate, and di-n-propylperoxy. Dicarbonate, bis (2-ethoxyethyl) peroxydicarbonate, tert-butyl peroxynecaprylate, tert-butyl peroxypivalate, (3,5,5-trimethyl Hexyl) peroxide, dipropylhydrazone peroxide, diethylhydrazone peroxide Things.

Moreover, in the said polymerization process, the weight average molecular weight of the obtained polymer can be adjusted by mix | blending a chain shifting agent, such as 2-mercaptoethanol.

After the (meth) acrylate polymer (A) is obtained, to the solution of the (meth) acrylate polymer (A), a bridging agent (B), an active energy ray-curable component (C) are added, and if necessary, added The photopolymerization initiator (D), silane coupling agent (E), additives, and the like are sufficiently mixed to obtain an adhesive composition P (coating solution) diluted with a solvent.

As a diluent for diluting the adhesive composition P to obtain a coating solution, aliphatic hydrocarbons such as hexane, heptane, and cyclohexane; aromatic hydrocarbons such as toluene and xylene; dichloromethane and two Halogenated hydrocarbons such as ethyl chloride; alcohols such as methanol, ethanol, propanol, butanol, 1-methoxy-2-propanol; acetone, methyl ethyl ketone, 2-pentanone, isophorone , Ketones such as cyclohexanone; esters such as ethyl acetate and butyl acetate; solvents such as ethyl cellosolve;

The concentration and viscosity of the coating solution prepared in this manner are not particularly limited as long as they are within the range possible for coating, and can be appropriately selected according to circumstances. For example, the concentration of the adhesive composition P may be diluted to 10% to 40% by mass. In addition, when a coating solution is obtained, the addition of a diluent solvent and the like is not necessary, and the adhesive composition P may not be added as long as the viscosity is possible for coating. In this case, the adhesive composition P can be used as a coating solution as it is.

[Adhesive]

The adhesive agent according to this embodiment can be preferably obtained by applying and drying the adhesive composition P to a desired object, and then curing the adhesive composition P by irradiation with active energy rays.

Drying of the adhesive composition P can be performed by air-drying, but it is usually performed by heat treatment (preferably hot-air drying). When the heat treatment is performed, the heating temperature is preferably 50 ° C to 150 ° C, and particularly preferably 70 ° C to 120 ° C. The heating time is preferably 10 seconds to 10 minutes, and particularly preferably 50 seconds to 2 minutes.

As the active energy rays, ultraviolet rays, electron rays, and the like are generally used. The irradiation amount of the active energy ray varies depending on the type of the energy ray, but in the case of ultraviolet rays, for example, it is preferably 50 mJ / cm2 to 1000 mJ / cm2 in terms of light amount, and particularly preferably 100 mJ / cm2 to 500 mJ / cm2. In the case of an electron beam, it is preferably about 10 krad to 1000 krad.

By drying the adhesive composition P and irradiating the active energy ray, the (meth) acrylate polymer (A) having a bridging functional group is bridged by the bridging agent (B) to form a first three-dimensional network structure. The active energy ray-curable components (C) are combined with each other to form a second three-dimensional network structure, and it is estimated that they are entangled with each other to form the structure X described above.

The adhesive obtained by curing the adhesive composition P acts on the alicyclic structure of the structure X and the (meth) acrylate polymer (A) described above, and is particularly useful in optical members such as polarizing plates, and the like. When a polycycloolefin-based optical member or a transparent conductive film is used as an adherend, it has high durability. In particular, it exhibits excellent durability under high temperature conditions or wet heat conditions. For example, under high temperature conditions of 80 ° C or humid conditions of 60 ° C and 90% RH, it can be prevented by leaving it for 500 hours. And suppress the occurrence of floating, peeling, air bubbles and so on.

The gel fraction of the adhesive according to this embodiment is preferably 30% to 99%, particularly preferably 40% to 95%, and still more preferably 76% to 90%. When the gel fraction is less than 30%, the cohesive force of the adhesive is insufficient, and durability and reworkability may be reduced. On the other hand, if the gel fraction is more than 99%, the adhesive force becomes too low, and the durability may be reduced. The above-mentioned gel fraction is a value after storage for 7 days (after the maturation period has elapsed) under the environment of 23 ° C. and 50% RH from the time of formation of the adhesive layer. When it is unknown whether it is a maturation period, the gel fraction should be within the above range after re-storing for 7 days in an environment of 23 ° C. and 50% RH.

[Adhesive sheet]

As shown in FIG. 1, the adhesive sheet 1A according to the first embodiment is composed of a release sheet 12, an adhesive layer 11 laminated on a release surface of the release sheet 12, and The base material 13 on the adhesive layer 11 is configured.

In addition, as shown in FIG. 2, the adhesive sheet 1B according to the second embodiment is composed of two peeling sheets 12 a and 12 b and is in contact with the peeling surfaces of the two peeling sheets 12 a and 12 b. The adhesive layer 11 held by the two release sheets 12a and 12b is configured. The release surface of the release sheet in the present specification refers to a surface having releasability in the release sheet, and includes both a surface subjected to a release treatment and a surface that exhibits releasability even without a release treatment.

In both of the adhesive sheets 1A and 1B, the adhesive layer 11 is composed of an adhesive formed by curing the above-mentioned adhesive composition.

The thickness of the adhesive layer 11 is appropriately determined according to the purpose of use of the adhesive sheets 1A and 1B, but it is usually 5 μm to 100 μm, and preferably 10 μm to 60 μm range. For example, when it is used as an optical member, especially as an adhesive layer for polarizing plates, it is preferable that it is 10 micrometers-50 micrometers, and it is especially preferable that it is 15 micrometers-30 micrometers.

The base material 13 is not particularly limited, and any base material used as a base material sheet of a general adhesive sheet can be used. For example, in addition to desired optical members, woven or non-woven fabrics using fibers such as rayon, acrylic, and polyester; synthetic paper; high-quality paper, cellophane, impregnated paper, and coated paper; Metal foils such as aluminum and copper; foams such as urethane foam and polyethylene foam; polyethylene terephthalate, polybutylene terephthalate, and polynaphthalene Polyester films such as ethylene glycol esters; cellulose films such as polyurethane films, polyethylene films, polypropylene films, and triethyl cellulose; polyvinyl chloride films, polyvinylidene chloride films, polyvinyl alcohol films, Plastic films such as ethylene-vinyl acetate copolymer film, polystyrene film, polycarbonate film, acrylic resin film, norbornene-based resin film, and cycloolefin resin film; a laminate of two or more of these and the like. The plastic film may be a uniaxially rolled film or a biaxially rolled film.

Examples of the optical member include a polarizing plate (polarizing film), a polarizer, a retardation plate (a retardation film), a viewing angle compensation film, a brightness enhancement film, a contrast enhancement film, a liquid crystal polymer film, a diffusion film, and a half Transmissive reflective film, etc. Among them, since the polarizing plate is easy to shrink and has a large dimensional change, it is preferably used as a base material for forming the adhesive (the above-mentioned adhesive layer 11) according to this embodiment from the viewpoint of durability. In particular, a polarizing plate made of a thin polycyclic olefin-based protective film (hereinafter referred to as a "COP polarizing plate") is not only easy to shrink, but also has a large dimensional change, and has a large contact angle and low adhesion. ,because This is more preferable as a base material for forming the adhesive (the above-mentioned adhesive layer 11) according to the present embodiment from the viewpoint of durability.

The thickness of the base material 13 varies depending on the type, but in the case of an optical member, for example, it is usually 10 μm to 500 μm, preferably 50 μm to 300 μm, and particularly preferably 80 μm to 150 μm.

As the release sheets 12, 12a, 12b, for example, polyethylene films, polypropylene films, polybutene films, polybutadiene films, polymethylpentene films, polyvinyl chloride films, vinyl chloride copolymer films, Polyethylene terephthalate film, polyethylene naphthalate film, polybutylene terephthalate film, polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene- ( Methacrylic acid copolymer film, ethylene- (meth) acrylate copolymer film, polystyrene film, polycarbonate film, polyimide film, fluororesin film, etc. Moreover, these bridge films can also be used. Furthermore, these laminated films may be used. The release sheets 12, 12a, and 12b preferably have active energy ray permeability.

It is preferable that the peeling surface (especially the surface which contacts the adhesive layer 11) of the said peeling sheet is peeled. Examples of the release agent used in the release treatment include alkyd-based, silicone-based, fluorine-based, unsaturated polyester-based, polyolefin-based, and wax-based release agents.

The thickness of the release sheets 12, 12a, and 12b is not particularly limited, but is usually about 20 μm to 150 μm.

In the production of the above-mentioned adhesive sheet 1A, the solution (coating solution) containing the adhesive composition P was coated and dried on the release surface of the release sheet 12, and after the coating film layer of the adhesive composition P was formed, On its coating layer, the substrate 13 Laminate. Then, the coating film layer is irradiated with active energy rays through the release sheet 12 to form an adhesive layer 11. The irradiation conditions of the active energy rays are as described above.

In addition, in the production of the adhesive sheet 1B, a coating solution containing the adhesive composition is applied and dried on the release surface of one release sheet 12a (or 12b), and then the adhesive composition P is applied. After the film layer, another peeling sheet 12b (or 12a) is laminated on the coating film layer. Then, the coating film layer is irradiated with active energy rays through the release sheet 12a (or 12b) to form the adhesive layer 11.

In addition, instead of irradiating the active energy ray to form the adhesive layer 11 through the release sheet as described above, a coating film layer of the adhesive composition P may be formed on the release sheet, and the coating film layer is exposed and irradiated. The active energy ray forms an adhesive layer 11, and thereafter, a base material or a release sheet is laminated on the adhesive layer 11. Furthermore, a coating film layer of the adhesive composition P may be directly formed on the substrate, and the coating film layer may be irradiated with active energy rays to form the adhesive layer 11.

As a method of applying the coating solution, for example, a bar coating method, a blade coating method, a roll coating method, a plate coating method, a mold coating method, a gravure coating method, or the like can be used.

Here, for example, in manufacturing a liquid crystal display device composed of a liquid crystal module and a polarizing plate, as the base material 13 of the adhesive sheet 1A, a polarizing plate is used, and the release sheet 12 of the adhesive sheet 1A is peeled off to expose the exposed The adhesive layer 11 may be bonded to the liquid crystal module.

In addition, for example, in a liquid crystal display device in which a retardation plate is disposed between a liquid crystal module and a polarizing plate, as an example, first, the adhesive sheet 1B One peeling sheet 12a (or 12b) is peeled off, and the adhesive layer 11 exposed by the adhesive sheet 1B and the retardation plate are bonded together. Then, the release sheet 12 of the adhesive sheet 1A using a polarizing plate as the base material 13 is peeled off, and the adhesive layer 11 exposed by the adhesive sheet 1A and the retardation plate are bonded together. Furthermore, the other peeling sheet 12b (or 12a) is peeled from the adhesive layer 11 of the said adhesive sheet B, and the adhesive layer 11 exposed by the adhesive sheet B and a liquid crystal element are bonded.

According to the above-mentioned pressure-sensitive adhesive sheets 1A and 1B, the durability of the pressure-sensitive adhesive layer 11 is excellent. Therefore, it can be prevented and suppressed from being adhered to a substrate 13 such as a COP polarizing plate or to be adhered even under high-temperature conditions or wet heat conditions. Floating, peeling, foaming, etc. occur between objects.

The haze value (value measured in accordance with JIS K7136: 2000) of the adhesive layer 11 in the adhesive sheets 1A and 1B is preferably 2% or less, particularly preferably 1.8% or less, and further preferably 1%. a bit. When the haze value is 2% or less, the transparency is very high, and it becomes an adhesive layer suitable for optical applications.

On the other hand, in the adhesive sheets 1A and 1B according to this embodiment, it is preferable to use a transparent conductive film as an adherend. In this case, the (meth) acrylate polymer (A) in the adhesive composition P preferably does not contain a carboxyl group-containing monomer as a monomer unit constituting the polymer. Thereby, it is possible to suppress the adverse effect of the acid component on the transparent conductive film. Specifically, it is possible to suppress corrosion of the transparent conductive film or change in the resistance value of the transparent conductive film.

Examples of the transparent conductive film include metals such as platinum, gold, silver, and copper; oxides of tin oxide, indium oxide, cadmium oxide, zinc oxide, and zinc dioxide; and tin-doped indium oxide (ITO) , Zinc oxide-doped indium oxide, fluorine-doped indium oxide, antimony-doped tin oxide, fluorine-doped tin oxide, aluminum-doped Transparent oxide film made of composite oxides such as zinc oxide; non-oxidizing compounds such as sulfide, lanthanum hexaboride, titanium nitride, and titanium carbide.

Further, an adhesive sheet 1A (hereinafter referred to as a “polarizer with an adhesive layer layer”) is used as a base material 13 for a polarizing plate, and the adhesive force is preferably 0.1N / 25mm to 25N relative to alkali-free glass. / 25mm, particularly preferably 2N / 25mm to 20N / 25mm. When the adhesive force is within the above range, it is possible to prevent floating, peeling, and the like from being adhered to a glass plate or the like. In addition, the adhesive force referred to here basically refers to an adhesive force measured by a 180 ° peeling method based on JIS Z0237: 2009, but a measurement sample is cut into a width of 25 mm and a length of 100 mm so that the measurement sample is relatively Adhesive (alkali-free glass) was attached at 0.5 MPa, 50 ° C for 20 minutes under pressure, and then left to stand for 24 hours at 23 ° C and 50% RH under normal pressure, and then measured at a peeling speed of 300 mm / min. Adhesion.

In addition, the above-mentioned polarizing plate with an adhesive layer is adhered to the alkali-free glass, and the adhesive force after being left for 14 days (adhesive force after being attached for 14 days) is preferably 0.5N / 25mm ~ 30N / 25mm, especially It is preferably 1N / 25mm to 25N / 25mm, and more preferably 2N / 25mm to 20N / 25mm. As described above, the increase in the adhesive force due to the passage of time is suppressed, so that the above-mentioned polarizing plate with an adhesive layer can be evaluated as a polarizing plate having excellent reworkability. In addition, the adhesive force referred to here basically refers to the adhesive force measured by the 180 ° peeling method based on JIS Z0237: 2009, but the measurement sample is cut into a width of 25 mm and a length of 100 mm to make the measurement sample relatively adhered. (Alkali-free glass), adhered at 0.5 MPa, 50 ° C for 20 minutes under pressure, and left for 14 days under the conditions of normal pressure 23 ° C and 50% RH, and measured at a peeling speed of 300 mm / min Adhesion.

The embodiment described above is to facilitate understanding of the principles of the present invention. What is described and described is not a description for limiting the present invention. Therefore, each element disclosed in the above embodiment includes all design changes and equivalents belonging to the technical scope of the present invention.

For example, the release sheet 12 of the adhesive sheet 1A may be omitted, and any one of the release sheets 12a and 12b in the adhesive sheet 1B may be omitted.

[Example]

Hereinafter, the present invention will be described in more detail through examples and the like, but the scope of the present invention is not limited by these examples and the like.

[Example 1]

1. Preparation of (meth) acrylate polymer

Into a reaction vessel including a stirrer, a thermometer, a reflux cooler, a dropping device, and a nitrogen introduction tube, 74 parts by mass of n-butyl acrylate, 5 parts by mass of methyl acrylate, and acrylic acid isobornyl 20 were charged. Parts by mass, 1 part by mass of 2-hydroxyethyl acrylate, 200 parts by mass of ethyl acetate, and 0.08 parts by mass of 2,2'-azobisisobutyronitrile, replacing the air in the reaction vessel with Nitrogen. The reaction solution was heated to 60 ° C. while stirring under this nitrogen atmosphere, and the reaction was allowed to proceed for 16 hours, followed by cooling to room temperature. Here, a part of the obtained solution was measured for molecular weight by a method described later, and it was confirmed that a (meth) acrylate polymer (A) having a weight average molecular weight (Mw) of 1.85 million was formed.

2. Preparation of adhesive composition

100 parts by mass of the (meth) acrylate polymer (A) obtained in the above step (1) (solid content conversion value; the same applies hereinafter); as a bridging agent (B), trimethylolpropane was modified 0.4 parts by mass of toluene diisocyanate (manufactured by Soken Chemical Co., Ltd., with a trade name of "TD-75"); as the active energy ray-curable component (C), tris (acryloxyethyl) isocyanate (manufactured by Toa Synthetic Corporation, product Name "aronixM-315" Molecular weight: 423, trifunctional ) 5 parts by mass; As a photopolymerization initiator (D), benzophenone and 1-hydroxycyclohexylbenzophenone will be 1: 1 mass 0.5 part by mass of the polymer (Irgacure 500, manufactured by Chiba Specialty Chemicals); as a silane coupling agent (E), it has a mercapto group as a functional group that reacts with an organic material, and 3-mercaptopropyltrimethoxy 0.3 parts by mass of a copolycondensate of methylsilane and methyltriethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd. under the trade name "X41-1810") was mixed, stirred sufficiently, and diluted with ethyl acetate to obtain adhesion A coating solution of a sexual composition.

Here, the combination of this adhesive composition is shown in Table 1. The details of the abbreviations and the like described in Table 1 are as follows.

[(Meth) acrylate polymer (A)]

BA: n-butyl acrylate

MA: methyl acrylate

HEA: 2-hydroxyethyl acrylate

IBXA: Isobornyl Acrylate

ADMMA: Adamantyl Methacrylate

DCPA: Dicyclopentyl acrylate

CHA: cyclohexyl acrylate

PhEA: 2-phenoxyethyl acrylate

AA: Acrylic

〔Cross-linking agent (B)〕

XDI: Trimethylolpropane modified xylene diisocyanate (manufactured by Soken Chemical Co., Ltd., trade name "TD-75")

TDI: Trimethylolpropane modified methylenephenyl diisocyanate (manufactured by Soken Chemical Co., Ltd., trade name "L-45")

[Silane coupling agent (E)]

E1: Co-condensation polymer of 3-mercaptopropyltrimethoxysilane and methyltriethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "X41-1810", mercapto equivalent: 450 g / mol)

E2: 3-mercaptopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBM-403")

3. Manufacturing of polarizing plate with adhesive layer

The obtained coating solution of the adhesive composition was a peeling sheet (manufactured by Lindec Corporation, peeled off) on one side of a polyethylene terephthalate film with a silicone release agent, SP-PET3811 (thickness: 38 μm), after being coated with a doctor blade applicator, heat-treated at 90 ° C. for 1 minute to form a coating film layer of the adhesive composition.

Next, a one-sided polarizer made of a polyvinyl alcohol film was protected with a triethylammonium cellulose film, and a COP polarizing plate having a thickness of 100 μm obtained by protecting the other surface with a cycloolefin polymer film was bonded to the above coating. The exposed side of the film layer. Thereafter, ultraviolet rays were irradiated through the release sheet under the following conditions to make the coating film layer into an adhesive layer, thereby obtaining a polarizing plate with an adhesive layer. The thickness of the adhesive layer was 20 μm.

<UV irradiation conditions>

‧Electrodeless lamp made by Fusion company using H bulb

‧Illumination 600mW / cm ² , 150mJ / cm ²

‧UV Illumination‧Light meter uses "UVPF-36" manufactured by Eyegraphics

[Examples 2 to 19, Comparative Examples 1 to 4]

In addition to curing the type and ratio of each monomer constituting the (meth) acrylate polymer (A), the weight average molecular weight of the (meth) acrylate polymer (A), the bridging agent (B), and active energy ray curing The types and / or blending amounts of the sexual component (C), the photopolymerization initiator (D), and the silane coupling agent (E) were changed as shown in Table 1, and the same operations as in Example 1 were performed to produce a tape. Polarizer with adhesive layer. In Example 4, as the antistatic agent, an adhesive composition was further blended with a pyridine salt-based ionic liquid (manufactured by Guangrong Chemical Co., Ltd., trade name "IL-P18").

Here, the weight average molecular weight (Mw) is a polystyrene equivalent weight average molecular weight measured (GPC measurement) under the following conditions using gel permeation chromatography (GPC).

<Measurement conditions>

‧GPC measurement device: manufactured by Tosoh Corporation, HLC-8020

‧GPC column (passed in the following order): made by Tosoh

TSK guard column HXL-H

TSK gel GMHXL (× 2)

TSK gel G2000HXL

‧Determination of flux: tetrahydrofuran

‧Measuring temperature: 40 ℃

[Test Example 1] (Measurement of gel fraction)

In Examples or Comparative Examples, instead of the polarizing plate used for the production of the polarizing plate with an adhesive layer, one surface of a polyethylene terephthalate film was used with a silicone-based release agent. Peel-off peeling sheet (Lintec) Co., Ltd., SP-PET3801, thickness: 38 μm), for the production of adhesive sheets. Specifically, on the exposed adhesive layer of the structure composed of the release sheet / adhesive layer (thickness: 20 μm) obtained in the manufacturing process of the example or the table example, the release-treated surface side phase was formed. The above-mentioned peeling sheet is laminated. Thereby, the adhesive sheet which consists of a peeling sheet / adhesive layer / peeling sheet structure was produced.

The obtained adhesive sheet was aged for 7 days under the conditions of 23 ° C. and 50% RH. Then, the adhesive sheet was made into a sample having a size of 80 mm × 80 mm, and the adhesive layer was wrapped with a polyester mesh (mesh size 200), and only the mass of the adhesive was weighed with a precision balance. Let the mass at this time be M1.

Next, the polyester mesh-wrapped adhesive was impregnated in ethyl acetate at room temperature (23 ° C) for 24 hours. After that, the adhesive was taken out and air-dried for 24 hours under an environment of a temperature of 23 ° C and a relative humidity of 50%, and further dried in an oven at 80 ° C for 12 hours. Only the mass of the dried adhesive was weighed with a precision balance. Let the mass at this time be M2. The gel fraction (%) is represented by (M2 / M1) × 100. The results are shown in Table 2.

[Test Example 2] (Measurement of Haze Value)

As a measurement sample, an adhesive sheet similar to the adhesive sheet used for measuring the gel fraction was prepared (aged for 7 days). About the adhesive layer (thickness: 20 micrometers) of this adhesive sheet, the haze value (%) was measured based on JIS K7136: 2000 using the haze meter (made by Nippon Denshoku Industries, NDH2000). The results are shown in Table 2.

[Test Example 3] (Measurement of Adhesive Strength)

The polarizing plate with an adhesive layer obtained in the examples or comparative examples was cut to produce samples having a width of 25 mm and a length of 100 mm. Release sheet from the sample After peeling off, pasting the sample on an alkali-free glass (Eagle XG) by an exposed adhesive layer, a pressure cooker made by Kurihara Manufacturing Co., Ltd. was pressurized at 0.5 MPa and 50 ° C for 20 minutes. . Thereafter, under conditions of 23 ° C. and 50% RH, it was left for 24 hours (1 day) or after 14 days, and then a tensile tester (Tensilon, manufactured by Orion) was used at a peeling speed based on JIS Z0237: 2009. At 300 mm / min and a peeling angle of 180 °, the adhesive force (adhesive force after 1 day and 14 days after application; N / 25 mm) was measured. The results are shown in Table 2.

[Test Example 4] (Durability Evaluation)

The polarizing plate with an adhesive layer obtained in the examples or comparative examples was cut to produce a sample having a size of 233 mm × 309 mm. As a sample, from the production of a polarizing plate with an adhesive layer (adhesive layer formation), a sample after storage for 7 days in an environment of 23 ° C. and 50% RH was prepared. The peeling sheet was peeled from this sample, and after the exposed adhesive layer was adhered on alkali-free glass (King Ning Corporation, Eagle XG), it was pressurized with a pressure cooker made by Kurihara Seisakusho at 0.5 MPa and 50 ° C. 20 minutes.

After that, it was put into an environment with the following durable conditions, and 500 hours later, the presence or absence of floating or peeling was confirmed using a 10-fold magnifying glass. The evaluation criteria are as follows. The results are shown in Table 2.

：: No floating or peeling was observed.

○: Floating or peeling of a size of 0.5 mm or less was confirmed.

×: Floating or peeling of a size of 0.6 mm or more was confirmed.

<Durable conditions>

‧80 ℃ dry

‧60 ℃, relative humidity 90% RH

【Table 2】

As can be seen from Table 2, the adhesive of the adhesive layer obtained in the examples has high adhesive strength and excellent durability.

[Industrial availability]

The adhesive of the present invention is suitable for optical members, particularly for the adhesion of polarizing plates. In addition, the adhesive sheet of the present invention is suitable for use as an optical member, and particularly suitable as an adhesive sheet for polarizing plates.

Claims (15)

An adhesive composition, comprising: a (meth) acrylate polymer (A) having a weight-average molecular weight of 900,000 to 3 million, and as a monomer unit constituting the polymer, containing 0.1% by mass to 30% by mass of a monomer having an alicyclic structure; a bridging agent (B); and an active energy ray-curable component (C). The adhesive composition according to item 1 of the scope of the patent application, wherein the alicyclic structure contains a cyclohexyl skeleton, a dicyclopentadiene skeleton, an adamantane skeleton, or an isobornyl skeleton. The adhesive composition according to item 1 of the scope of patent application, wherein the (meth) acrylate polymer (A), as a monomer unit constituting the polymer, further contains 0.1% to 10% by mass of A monomer having a hydroxyl group. The adhesive composition according to claim 1, wherein the (meth) acrylate polymer (A) does not substantially contain a monomer having a carboxyl group as a monomer unit constituting the polymer. The adhesive composition according to item 1 of the scope of patent application, wherein the bridging agent (B) is an isocyanate bridging agent. The adhesive composition according to item 1 of the scope of patent application, wherein the active energy ray-curable component (C) is a polyfunctional acrylate monomer having a molecular weight of less than 1,000. The adhesive composition according to item 6 of the patent application scope, wherein the polyfunctional acrylate monomer has a cyclic structure. The adhesive composition according to item 1 of the scope of patent application, wherein the content of the active energy ray-curable component (C) in the adhesive composition is relative to the (meth) acrylate polymer (A) 100 parts by mass, 1 to 30 parts by mass. The adhesive composition according to item 1 of the patent application scope, further comprising a photopolymerization initiator (D). An adhesive is an adhesive formed by curing the adhesive composition according to any one of claims 1 to 9 of an application for a patent by irradiation of active energy rays. An adhesive sheet is characterized in that it is an adhesive sheet provided with a substrate and an adhesive layer, and the adhesive layer is composed of the adhesive described in item 10 of the scope of patent application. The adhesive sheet according to item 11 of the scope of patent application, wherein the substrate is an optical member. The adhesive sheet according to item 12 of the patent application scope, wherein the optical member is a polarizing plate. The pressure-sensitive adhesive sheet according to Item 12 of the application, wherein the optical member has a polycycloolefin-based film. An adhesive sheet is characterized in that it is an adhesive sheet comprising two release sheets and an adhesive layer held by the release sheet so as to be in contact with the release surfaces of the two release sheets, and the adhesive The layer is composed of the adhesive described in item 10 of the patent application.