JP2001049210A - Adhesive sheets - Google Patents

Abstract

(57) [Summary] [Problem] Adhesion that has no adverse effect on the inside of electronic equipment due to hydrocarbon gas and further siloxane gas, and has excellent original adhesive properties such as high adhesive strength, and excellent release properties of release liner. Provide sheets. SOLUTION: In an adhesive sheet comprising an adhesive sheet main body and a release liner bonded to the adhesive sheet, carbonization when the adhesive sheet main body from which the release liner is peeled is heated at 85 ° C for 10 minutes. The amount of generated gas of hydrogen is 0.05 μg / cm ²
The following, the adhesive layer in the adhesive sheet body,
A) 50-100% by weight of a polyester polymer containing an aliphatic polycarbonate as an essential polyol component; and B) 50-0% of an acrylic polymer having a glass transition temperature of -10 ° C or less. % By weight, wherein the release layer of the release liner is made of low-density polyethylene.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-sensitive adhesive sheet (sheet) used for bonding inside an electronic device, the pressure-sensitive sheet comprising a pressure-sensitive adhesive sheet body and a release liner bonded thereto.
And tape).

[0002]

2. Description of the Related Art Since adhesive sheets are used for various purposes, those having high tack, high adhesiveness and cohesiveness are designed. Particularly in recent years, adhesive sheets have been used inside electronic devices. In such applications, in addition to the above adhesive properties, maintenance of airtightness, reduction of volatile gas components, and the like are also required.

By the way, in the case of pressure-sensitive adhesive sheets, a release liner is stuck to the surface of the pressure-sensitive adhesive layer until the adhesive is used from the viewpoint of protection of the pressure-sensitive adhesive surface and handleability. Then, in order to obtain good peelability,
A release liner whose surface is treated with silicone is used. However, when such a release liner is used, silicone migrates to the adhesive surface, and siloxane gas is generated inside the electronic device, which may cause corrosion and malfunction of the electronic device.

[0004] For this reason, recently, the use of a release liner that has not been subjected to a silicon treatment has been studied, and as a typical example, attempts have been made to use a polyolefin film such as a polyethylene film. Such a polyolefin film is known to exhibit particularly good releasability to an adhesive layer or the like containing a polyester-based polymer having a carbonate bond in a molecule as a main component. The performance as a liner can be fully expected.

[0005]

However, according to the study of the present inventors, even though the use of the above-mentioned polyolefin film can prevent the generation of siloxane gas, it can cause corrosion and malfunction of electronic equipment. It has been found that adverse effects such as these cannot be avoided reliably. The present inventors have further examined the cause of this. As a result, the polyolefin film contained a small amount of hydrocarbons having 8 to 20 carbon atoms, which migrated to the adhesive surface, and caused a high temperature inside the electronic device. It has been found that it evaporates as a gas component under the use environment and adversely affects electronic equipment.

SUMMARY OF THE INVENTION In view of such circumstances, an object of the present invention is to provide an adhesive sheet in which a hydrocarbon gas is prevented from adversely affecting electronic equipment. Further, the present invention has not only the adverse effect of the hydrocarbon gas, but also the adverse effect of the siloxane gas. Therefore, the corrosion and malfunction of the electronic device can be reliably avoided, and the original adhesive properties such as high adhesive strength are excellent. Another object of the present invention is to provide an adhesive sheet having excellent release properties of the release liner.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies on the above object, and as a result, have regulated the amount of hydrocarbons having 8 to 20 carbon atoms contained in the release liner. It has been found that when the amount of hydrocarbons transferred to the pressure-sensitive adhesive layer is reduced to a specific value or less, adverse effects on electronic devices due to the generation of hydrocarbon gas can be avoided.

Further, as such a release liner, a material composed of low-density polyethylene, particularly linear low-density polyethylene, is selectively used, and as a pressure-sensitive adhesive layer for bonding the same, a carbonate bond is present in the molecule. When a specific polyester-based polymer or a specific acrylic-based polymer and a specific acrylic-based polymer are used as main components, there is no adverse effect of the hydrocarbon gas and further the siloxane gas, so that corrosion and malfunction of electronic devices can be reliably avoided. At the same time, it has been found that adhesive sheets having excellent adhesive properties such as high adhesive strength and excellent release properties of the release liner can be obtained.

The present invention has been made based on these findings.
It is completed. That is, the present invention provides an adhesive sheet
Adhesive sheet consisting of a main body and a release liner bonded to the main body
Adhesive sheets (claim 1), characterized in that the amount of generated gas of hydrocarbons when heating the main body at 85 ° C. for 10 minutes is 0.05 μg / cm ² or less. The present invention relates to the pressure-sensitive adhesive sheets (claim 4) suitable for bonding applications.

In the present invention, the pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet itself as the pressure-sensitive adhesive sheet having such a constitution is required to contain: A) an aliphatic polycarbonate diol. Polyester-based polymer 50 to 10 as a polyol component
0% by weight and B) 50 to 0% by weight of an acrylic polymer having a glass transition temperature of -10 ° C. or lower, and the release sheet of the release liner is made of low-density polyethylene. (2) In particular, it is possible to provide an adhesive sheet (claim 3) in which the release layer of the release liner is made of linear low-density polyethylene.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION An adhesive sheet of the present invention comprises an adhesive sheet main body and a release liner bonded to the adhesive sheet. The amount of gas generated from hydrocarbons when heated for 10 minutes is 0.05
[mu] g / cm ² or less, preferably 0.03 [mu] g / cm ² or less,
Most preferably, it is 0 μg / cm ² .
Here, most of the above hydrocarbons have 8 to 20 carbon atoms.
If this hydrocarbon is reduced as described above, even if this adhesive sheet is used for bonding inside electronic equipment, corrosion and malfunction of electronic equipment caused by hydrocarbon gas will occur. It does not cause any problems. When the amount of generated gas exceeds 0.05 μg / cm ² , the above problem cannot be avoided.

In the present invention, the material composition of the adhesive sheet body and the release liner bonded thereto is not particularly limited as long as the above-mentioned characteristics are satisfied. However, in order to prevent not only the above-mentioned adverse effects of the hydrocarbon gas but also the adverse effects of the generation of siloxane gas, and to obtain excellent adhesive properties such as high adhesive strength and further excellent releasability, adhesive sheets are used. The pressure-sensitive adhesive layer in the main body is A)
50-100% by weight of a polyester polymer containing an aliphatic polycarbonate as an essential polyol component
And B) a composition comprising 50 to 0% by weight of an acrylic polymer having a glass transition temperature of -10 ° C or lower, and a release layer of a release liner made of low-density polyethylene, particularly linear low-density polyethylene. It is desirable that it is.

In the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet body, A
The polyester polymer of the component is a polyester containing an aliphatic polycarbonate diol as an essential polyol component, that is, 50% by weight or more, preferably 60% by weight of the aliphatic polycarbonate diol. % Or more polio
And a polybasic acid component, having a weight average molecular weight of 10,000 to 200,000, preferably 20,000 to 15
Those having a number of 10,000, more preferably 30,000 to 120,000 are used. If the molecular weight of the polyester-based polymer is too low, good results cannot be obtained in the adhesive properties such as adhesive strength.

[0014] The aliphatic polycarbonate is
The following formula: (Wherein R is an aliphatic hydrocarbon group having 2 to 20 carbon atoms), is a diol having a repeating unit represented by the formula:
As a commercially available product, "PLAC" manufactured by Daicel Chemical Industries, Ltd.
CEL CD220PL ”,“ CD210PL ”,
"CD205PL", "CD220", "CD2"
10 ". Other polyol components include straight-chain diols such as ethylene glycol, propylene glycol, butanediol, hexanediol, octanediol, decanediol, and octadecandiol. Are used.

The polybasic acid component to be reacted with the polyol component has a molecular skeleton of an aliphatic or alicyclic hydrocarbon group having 2 to 20 carbon atoms. May be linear or branched. For example, malonic acid, succinic acid, methyl succinic acid, adipic acid, sebacic acid, 1,12-dodecandioic acid, 1,14-tetradecandioic acid, n-hexyl adipic acid, tetrahydrophthalic acid, endmethylene tetrahydrophthalic acid and the like Dicarboxylic acids and derivatives such as acid anhydrides thereof are used.

In the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet body, B
The acrylic polymer as the component is used for compensating for a case where the polyester polymer as the component A alone has poor initial adhesiveness. Such an acrylic polymer has an alkyl group having 4 to 14 carbon atoms (meth)
A polymer of a monomer containing 50 to 100% by weight of an alkyl acrylate, having a glass transition temperature of -10C or lower, preferably -15C or lower (usually up to about -90C).
It is what becomes. When the glass transition temperature is higher than −10 ° C., the effect of improving the initial adhesiveness is inferior.

The alkyl (meth) acrylate having an alkyl group having 4 to 14 carbon atoms includes butyl, isobutyl, isoamyl, hexyl, heptyl, 2-ethylhexyl, isooctyl, isononyl. And those having an alkyl group such as a group, a lauryl group and an isomyristyl group. Along with these (meth) acrylic acid alkyl esters, modifying monomers such as vinyl acetate, styrene, 2-hydroxyethyl (meth) acrylate, and (meth) acrylonitrile may be used. The use of an acid component such as (meth) acrylic acid as the modifying monomer is not preferred because of the problem of corrosion of electronic devices to metals.

In the pressure-sensitive adhesive layer of the main body of the pressure-sensitive adhesive sheet, the proportion of the polyester polymer of component A and the acrylic polymer of component B is such that the polyester polymer of component A Is 50 to 100% by weight, preferably 6
0 to 100% by weight, 50 to 50% by weight of acrylic polymer of component B
It is preferably 0% by weight, preferably 40 to 0% by weight. When preparing a mixture of the polyester polymer of the component A and the acrylic polymer of the component B, the respective polymer components are separately synthesized and then mixed in a lump or a solution, or one of the polymer components is mixed. It may be prepared by a method of polymerizing the other in the coalescence, or may be prepared by a method of polymerizing both at the same time.

The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is mainly composed of the polyester polymer of the above-mentioned component A or the acrylic polymer of the above-mentioned component B as a main component. Thus, the adhesive property can be improved. In the crosslinking treatment, a polyisocyanate compound, an epoxy compound, an aziridine compound, or the like may be added as a crosslinking agent, and this may be reacted with a functional group such as a hydroxyl group contained in the polymer. In such an adhesive layer, if necessary, a tackifier, an inorganic or organic filler, a metal powder, a powder such as a pigment, a particulate material, a conventionally known various material such as a foil material, etc. Can be optionally included.

The pressure-sensitive adhesive sheet itself may be composed of only the pressure-sensitive adhesive layer. However, usually, the pressure-sensitive adhesive layer is provided on one or both sides of a support, and the sheet-like or tape-like shape is used. It is desirable to take the form. As the support, a plastic film such as a polyester film, paper, a nonwoven fabric, a foam, a metal foil, a laminate thereof, or the like is used. Also,
The thickness of the pressure-sensitive adhesive layer is usually preferably in the range of 5 to 200 μm.

As the release liner to be bonded to such an adhesive sheet body, a release liner which is not subjected to silicone treatment and which is made of low-density polyethylene, particularly linear low-density polyethylene, is preferably used. The release liner may be a single-layer film made of the polyethylene alone, or a multilayer film in which the polyethylene is used as a release layer and two or more other plastic films are laminated thereon. The low-density polyethylene described above has a density in the range of 0.90 to 0.93, and the linear low-density polyethylene is a linear low-density polyethylene obtained by copolymerizing ethylene and α-olefin. Α-olefins include butene-1 and pentene-
1, hexene-1, heptene-1, octene-1, nonene-1, 4-methylpentene-1, decene-1 and the like are used.

In the present invention, in order to reduce the amount of gas generated from hydrocarbons to 0.05 μg / cm ² or less when the pressure-sensitive adhesive sheet body from which the release liner is peeled is heated at 85 ° C. for 10 minutes, The amount of the hydrocarbon having 8 to 20 carbon atoms contained in the release liner may be regulated to reduce the amount of the hydrocarbon transferred from the release liner to the pressure-sensitive adhesive layer. For example, the amount of hydrocarbons having 8 to 20 carbon atoms in the low-density polyethylene may be reduced by subjecting a low-density polyethylene pellet or film to solvent extraction or heat treatment. In the case of a multilayer film, the absolute amount of hydrocarbons having 8 to 20 carbon atoms in the entire release liner can be reduced by making the release layer made of low-density polyethylene an extremely thin layer. May be adopted.

The pressure-sensitive adhesive sheets of the present invention generally have an adhesive strength (adherend: aluminum plate) of 0. 0 when the specific pressure-sensitive adhesive sheet body and the specific release liner are combined. 5 kg / 20 mm width or more, preferably 0.8 kg /
20 mm width or more, and the release force of the release liner is 20
The width is 0 g / 50 mm or less, preferably 100 g / 50 mm or less, more preferably 50 g / 50 mm or less.

The pressure-sensitive adhesive sheets of the present invention, having such a structure, are capable of generating a hydrocarbon gas even when the release liner is peeled off at the time of bonding and applied to bonding of electronic equipment parts. An adverse effect on the inside of the electronic device can be avoided. In addition, a specific polyester polymer having a carbonic acid bond in the molecule as the adhesive layer or a material containing the same as a specific acrylic polymer as a main component is used as a pressure-sensitive adhesive layer. In the case of using the one made of high density polyethylene, there is no adverse effect due to the generation of the hydrocarbon gas and further the siloxane gas, and it is possible to reliably avoid the corrosion and malfunction of the electronic device, and furthermore, the high adhesion force etc. Excellent adhesive properties can be exhibited, and the release liner can be easily peeled off from the adhesive sheet body.

[0025]

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the scope of the present invention is not limited by the following examples. In the following, “parts” means “parts by weight”.

Example 1 A four-necked separable flask equipped with a stirrer, a thermometer and a water separating tube was charged with a liquid polycarbonate ["PLACCEL CD220" manufactured by Daicel Chemical Industries, Ltd.
PL ", hydroxyl value 56.1 KOH mg / g] 250 parts, sebacic acid 26.6 parts, titanium tetraisopropoxide 0.1 part as a catalyst, and in the presence of small amounts of toluene and xylene as a reaction water discharge solvent. The temperature was raised to 180 ° C. while stirring was started, and maintained at this temperature. After a while, effluent separation of water was observed, and the reaction began to proceed. The reaction was continued for about 25 hours, and the weight average molecular weight was 3.8.
Ten thousand polyester-based polymer A solutions were obtained.

To the solution of the polyester polymer A, 3 parts (solid content) of a tolylene diisocyanate adduct of trimethylolpropane ("Coronate L" manufactured by Nippon Polyurethane Co.) was added as a crosslinking agent. And mixed to form a solution of the pressure-sensitive adhesive composition. This solution was applied on a 38 μm-thick polyethylene terephthalate film (hereinafter referred to as PET film) using an applicator,
For 3 minutes to form an adhesive layer having a thickness of 30 μm. On this pressure-sensitive adhesive layer, as a release liner, a pellet of linear low-density polyethylene (copolymer resin of ethylene and octene-1) was extracted with toluene, and dried under reduced pressure to form a film. A 150 μm film (density 0.915) was attached to form an adhesive tape.

Example 2 100 parts of toluene, 50 parts of isononyl acrylate, 40 parts of ethyl acrylate, 6 parts of methyl methacrylate were placed in a reaction vessel equipped with a cooling pipe, a nitrogen introducing pipe, a thermometer and a stirrer. 2-hydroxyethyl acrylate 4
And 0.2 parts of benzoyl peroxide, and polymerized in a nitrogen stream to obtain a solution of an acrylic polymer B having a glass transition temperature of -42 ° C and a weight average molecular weight of 450,000.

The solution of the acrylic polymer B and the solution of the polyester polymer A obtained in Example 1 were mixed with the acrylic polymer B25 per 75 parts of the polyester polymer A.
And 3 parts (solid content) of a tolylene dipropocyanate adduct of trimethylolpropane ("Coronate L" manufactured by Nippon Polyurethane Co., Ltd.), and then mixed. A solution of the composition was obtained. Using this solution of the pressure-sensitive adhesive composition, a pressure-sensitive adhesive tape was prepared in the same manner as in Example 1.

Example 3 A low-density polyethylene film (density 0.92) having a thickness of 150 μm was prepared, subjected to an extraction treatment in which the film was immersed in toluene at 40 ° C. for 7 days, and then dried. , And a release liner. An adhesive tape was produced in the same manner as in Example 1 except that this release liner was used.

Example 4 An adhesive tape was produced in the same manner as in Example 2 except that a low-density polyethylene film subjected to the same extraction treatment as in Example 3 was used as the release liner.

Comparative Example 1 An adhesive tape was prepared in the same manner as in Example 1 except that a high-density polyethylene film (density 0.94) having a thickness of 150 μm was prepared and used as a release liner as it was. did.

Comparative Example 2 As the release liner, the thickness used in Example 3 was 150 μm.
m low-density polyethylene film (density 0.92)
An adhesive tape was prepared in the same manner as in Example 1 except that the extraction tape was not subjected to extraction treatment by immersion in toluene, and was used as it was.

With respect to each of the adhesive tapes of Examples 1 to 4 and Comparative Examples 1 and 2, carbonization was performed by heating the adhesive tape body from which the release liner was peeled off at 85 ° C. for 10 minutes by the following method. The amount of generated gas of hydrogen was measured. Separately, the adhesive force of each of the above-mentioned adhesive tapes and the peeling force of the peeling liner were measured by the following methods. The results of these measurements were as shown in Table 1.

<Measurement of amount of generated gas of hydrocarbon>
The stripping liner was removed, weighed, and heated at 85 ° C. for 10 minutes using a purge & trap head space sampler, and the generated gas was cold trapped at −120 ° C. With respect to this trap (generated gas) component, the amount of generated gas of a hydrocarbon having 8 to 20 carbon atoms was measured by a gas chromatograph / mass spectrometer.

<Measurement of Adhesive Strength> Adhesive tape was 20 mm × 1
It was cut to 00 mm, the release liner was peeled off from the adhesive tape in an atmosphere of 23 ° C. and 65% RH, and pressed on an aluminum plate as an adherend under the condition of 2 kg roller and one round trip.
After 30 minutes, at a peel speed of 300 mm / min, 180 ° C.
Peel adhesion (kg / 20 mm width) was measured.

<Measurement of Peeling Force of Peeling Liner> The adhesive tape was cut into 50 mm × 100 mm, and the PET film side was fixed to a stainless steel plate with a double-sided tape.
The peeling force (g / 50 mm width) when the release liner was peeled off from the adhesive tape at a pulling rate of 300 mm / min in an atmosphere of 65% RH was measured.

[0038]

As is clear from the results shown in Table 1, the pressure-sensitive adhesive tapes of Examples 1 to 4 have a smaller amount of generated hydrocarbon gas than the pressure-sensitive adhesive tapes of Comparative Examples 1 and 2. There is no adverse effect on electronic equipment, and it is a combination of a specific polyester polymer or a pressure-sensitive adhesive layer mixed with an acrylic polymer and a release liner made of low-density polyethylene film. It has no adverse effects on electronic equipment, has a large adhesive strength, and has excellent release properties of the release liner.

[0040]

As described above, according to the present invention, the amount of hydrocarbon generated gas when the adhesive sheet body from which the release liner has been peeled off is heated at 85 ° C. for 10 minutes is 0.05 μg / cm.
^By adopting a configuration of ² or less, it is possible to provide adhesive sheets that avoid adverse effects when used for bonding of electronic devices. Further, in the present invention, in addition to the above constitution, a specific polyester polymer having a carbonate bond in the molecule or a pressure-sensitive adhesive composition containing this and a specific acrylic polymer as a main component are combined with a low-density adhesive. By combining with a release liner made of polyethylene, the above-mentioned hydrocarbon gas and further siloxane gas are not generated, so that corrosion and malfunction of electronic equipment can be reliably avoided, and high adhesive strength etc. Adhesive sheets having excellent original adhesive properties and excellent release properties of the release liner.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yasuyuki Tokunaga 1-1-2 Shimohozumi, Ibaraki City, Osaka Prefecture Inside Nitto Denko Corporation (72) Inventor Hiroshi Yamamoto 1-1-2 Shimohozumi, Ibaraki City, Osaka Prefecture Nitto Denko Corporation (72) Inventor Naoyuki Nishiyama 1-1-2 Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation F-term (reference) 4J004 AA02 AA10 AA15 AB01 BA02 CA02 CA06 CA08 CB02 CC02 DA02 DB02 FA05

Claims (4)

[Claims] 1. An adhesive sheet comprising an adhesive sheet body and a release liner bonded thereto, wherein the adhesive sheet body from which the release liner has been peeled is heated at 85 ° C. for 10 minutes. The amount of hydrocarbon generated gas is 0.05 μg / cm ²
Adhesive sheets characterized by the following. 2. The pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet body,
A) 50-100% by weight of a polyester polymer containing an aliphatic polycarbonate as an essential polyol component; and B) 50-0% of an acrylic polymer having a glass transition temperature of -10 ° C or less. The pressure-sensitive adhesive sheet according to claim 1, wherein the release liner comprises a low-density polyethylene as a release layer. 3. The adhesive sheet according to claim 2, wherein the release liner comprises a linear low density polyethylene as a release layer. 4. The adhesive sheet according to claim 1, which is used for bonding inside an electronic device.