TWI801499B - Double-sided adhesive sheet and its application - Google Patents

Abstract

The present invention provides a double-sided adhesive sheet, which is a film and has strong adhesiveness, and suppresses excessive adhesion, and is endowed with re-adhesive suitability. The double-sided adhesive sheet is characterized in that it has an adhesive layer on both sides of the core material, and the adhesive layer is composed of 100 parts by mass of (meth)acrylic copolymer, 40-70 parts by mass of tackifying resin part and an adhesive composition of 0.01 to 5 parts by mass of a crosslinking agent, wherein the thickness of the core material is 1 to 12 μm, and the thicknesses of the adhesive layers on both sides of the core material are respectively It is 1~12μm and meets certain conditions.

Description

Double-sided adhesive sheet and its application

The present invention relates to a double-sided adhesive sheet, its manufacturing method and its use.

Adhesive sheets (adhesive tapes) have been widely used for fixing parts of OA equipment and electronic equipment. In recent years, as OA equipment and electronic equipment have become thinner and smaller, the thickness of the adhesive sheet used to fix the components is also required to be thinner.

Generally, the thinner the adhesive sheet, the weaker the adhesive force, and the market requires thinner and stronger adhesive sheets. On the other hand, due to the reduction in strength associated with thinning and shortening of parts, the problem of parts being broken during re-adhesion has also become a problem. Therefore, a tape with strong adhesion and suitable for re-adhesion is required.

As an adhesive sheet used for fixing parts of OA equipment and electronic equipment, for example, an adhesive tape is described in Patent Document 1, which has an adhesive layer on at least one side of the base material, and the thickness direction of the base material is The 25% compressive strength is less than 300kPa, the total thickness is less than 250μm, and the probe initial tack (ProbeTack) is more than 2.0N/cm ² .

In addition, in Patent Document 2, a double-sided adhesive sheet is described, which is used to fix and constitute a portable electronic device. A component of a sub-device is provided with an acrylic adhesive layer, and the acrylic adhesive layer has an acrylic polymer containing 9 to 30% by mass of a constituent unit derived from a polar monomer as a base polymer, and the The thickness of the acrylic adhesive layer is 280 μm or more.

prior art literature

patent documents

Patent Document 1: Japanese Patent Laid-Open No. 2016-89145

Patent Document 2: Japanese Patent Laid-Open No. 2015-147873

However, neither Patent Document 1 nor Patent Document 2 mentions the characteristics of being a thin film and having strong adhesiveness and re-adhesiveness.

The present invention was made in view of the above-mentioned problems, and found that both a film and a It has strong adhesiveness, suppresses excessive adhesion, and is endowed with re-adhesive suitability, thereby solving the above-mentioned problems.

That is, the present invention is as follows:

[1] A double-sided adhesive sheet having an adhesive layer formed of an adhesive composition containing 100 parts by mass of a (meth)acrylic acid-based adhesive on both sides of a core material. copolymer, 40-70 parts by mass of tackifying resin and 0.01-5 parts by mass of crosslinking agent, wherein the thickness of the core material is 1-12 μm, and the adhesive layer on both sides of the core material The thickness of each is 1~12μm, and the following conditions (i) and (ii) are satisfied, (i) the adhesive surface of the adhesive layer is attached to the SUS plate and it is kept under the environment of 25°C/50%RH The adhesion force A measured after standing for 20 minutes is 1000~1600g/25mm; (ii) the adhesive surface of the adhesive layer is attached to the SUS plate and kept under 25°C/50%RH for 24 hours. When the measured adhesive force is regarded as the adhesive force B, the value of the adhesive force B/adhesive force A is 1.00 to 1.25.

[2] The double-sided adhesive sheet according to the above item [1], wherein the tackifying resin contains a styrene-based tackifying resin and a rosin-based tackifying resin.

[3] The double-sided adhesive sheet according to the above item [2], wherein the content of the styrene-based tackifying resin is larger than the content of the rosin-based tackifying resin.

[4] The double-sided adhesive sheet according to item [3] above, wherein the content of the styrene-based tackifying resin is 20-35 parts by mass, and the content of the rosin-based tackifying resin is 18-32 parts by mass. parts by mass.

[5] The double-sided adhesive sheet according to item [4] above, wherein the content of the styrene-based tackifying resin is 27-35 parts by mass, and the content of the rosin-based tackifying resin is 26-30 parts by mass. parts by mass.

[6] The double-sided adhesive sheet according to any one of the above [1] to [5], which is a double-sided adhesive sheet for a heat sink.

[7] The double-sided adhesive sheet according to any one of the above [1] to [5], which is a double-sided adhesive sheet for a light-shielding tape.

The double-sided adhesive sheet of the present invention is a thin film, has strong adhesiveness, and is endowed with re-adhesive suitability by suppressing excessive adhesion. Therefore, the double-sided adhesive sheet of the present invention contributes to miniaturization of electronic equipment, and when applied to electronic components, it can firmly connect the components to each other and can be peeled off from the components without causing damage when re-adhesion is required.

Hereinafter, the present invention will be described in detail, but the present invention is not limited to these specific embodiments.

The double-sided adhesive sheet of the present invention is characterized in that it has an adhesive layer formed of an adhesive composition containing 100 parts by mass of a (meth)acrylic acid-based adhesive on both sides of the core material. Copolymer, 40-70 parts by mass of tackifying resin and 0.01-5 parts by mass of crosslinking agent, wherein the thickness of the core material is 1-12 μm, and the adhesive on both sides of the core material The thicknesses of the adhesive layers are each 1-12 μm, and the following conditions (i), (ii) are satisfied, (i) the adhesive surface of the adhesive layer is attached to the SUS plate and heated at 25°C/50% The adhesion force A measured after being placed in the RH environment for 20 minutes is 1000~1600g/25mm; (ii) the adhesive surface of the adhesive layer is attached to the SUS board and protected against 24 When the adhesive force measured after 1 hour is regarded as the adhesive force B, the value of the adhesive force B/adhesive force A is 1.00~1.25.

Next, the configuration will be described in detail.

〔(Meth)acrylic copolymer〕

(Meth)acrylic copolymer means that at least one of the monomers constituting the main component is a monomer having a (meth)acryl group, which is obtained by adding (meth)acrylate, etc. A copolymer obtained by polymerizing a monomer having a (meth)acryl group and a monomer component copolymerizable therewith.

As a monomer component which forms a (meth)acrylic-type copolymer, the (meth)acrylate mentioned later and the monomer containing the crosslinkable group which can be copolymerized with this are mentioned, for example.

It should be noted that in this specification, "(meth)acryl" includes both "acryl" and "methacryl", and "(meth)acrylate" includes "acrylate" and "methacrylate". "Both" and "(meth)acryl" include both "acryl" and "methacryl".

Examples of (meth)acrylates include alkyl (meth)acrylates, alicyclic (meth)acrylates, aryl (meth)acrylates, aralkyl (meth)acrylates, alkane Oxyalkyl (meth)acrylates, alkoxypolyalkylene glycol mono(meth)acrylates, aryloxyalkyl (meth)acrylates.

As alkyl(meth)acrylates such as meth(meth)acrylate, ethyl(meth)acrylate base) acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, Isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, n-decyl (meth)acrylate ) acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, octadecyl (meth)acrylate, isostearyl Alkyl (meth)acrylates.

Examples of alicyclic (meth)acrylates include cycloalkyl (meth)acrylates such as cyclohexyl (meth)acrylate and 4-tert-butylcyclohexyl (meth)acrylate, iso Bornyl (meth)acrylate, Adamantyl (meth)acrylate.

As aryl (meth)acrylate, a phenyl (meth)acrylate is mentioned, for example, As aralkyl (meth)acrylate, a benzyl (meth)acrylate is mentioned, for example.

Examples of alkoxyalkyl (meth)acrylates include methoxymethyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, 3-ethoxypropyl (meth)acrylate, 4-methoxybutyl (meth)acrylate, 4 - Ethoxybutyl (meth)acrylate.

Examples of alkoxy polyalkylene glycol mono(meth)acrylates include methoxydiethylene glycol mono(meth)acrylate, methoxydipropylene glycol mono(meth)acrylate, ethyl Oxytriethylene glycol mono(meth)acrylate, ethoxydiethylene glycol mono(meth)acrylate, methoxytriethylene glycol mono(meth)acrylate.

Examples of aryloxyalkyl (meth)acrylates include phenoxymethyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, 2-methylphenoxyethyl (meth)acrylate, xyloxymethyl (meth)acrylate, naphthyloxymethyl (meth)acrylate.

(Meth)acrylate may be used individually by 1 type, and may use 2 or more types.

In 100% by mass of monomer components used to form a (meth)acrylic copolymer, the amount of (meth)acrylate used is preferably 65% by mass or more, more preferably 70% by mass or more, and even more preferably 75% by mass or more. 99% by mass. Such a form is preferable in terms of the adhesive force of the obtained adhesive layer and suppression of excessive adhesion. Moreover, it is preferable that 60 mass % or more is an alkyl (meth)acrylate in 100 mass % of (meth)acrylates.

Examples of the crosslinkable group-containing monomer include carboxyl group-containing monomers and hydroxyl group-containing monomers.

Examples of carboxyl group-containing monomers include (meth)acrylic acid, β-carboxyethyl (meth)acrylate, 5-carboxypentyl (meth)acrylate, crotonic acid, maleic acid, and fumaric acid. .

Examples of hydroxyl-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 3-chloro- 2-Hydroxypropyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate.

The crosslinkable group-containing monomer may be used alone or in combination of two or more.

In 100% by mass of the monomer components used to form a (meth)acrylic copolymer, the amount of the crosslinkable group-containing monomer used is preferably 0.1 to 15% by mass, more preferably 0.5 to 10% by mass, and further Preferably it is 1-8 mass %. If it is such a form, a suitable crosslinked structure can be formed by reaction of a (meth)acrylic-type copolymer and the crosslinking agent mentioned later.

The said monomer component may contain other monomers other than a (meth)acrylate and a crosslinkable group containing monomer.

Examples of other monomers include amino group-containing monomers, amide group-containing monomers, glycidyl group-containing monomers, vinyl group-containing monomers, and polymerizable macromonomers.

As amino group-containing monomers, for example, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate; as amide group-containing monomers, for example (form base) acrylamide, N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide; examples of glycidyl group-containing monomers include glycidyl (meth)acrylate , 4-hydroxybutyl (Meth)acrylate glycidyl ether; Examples of vinyl group-containing monomers include vinyl acetate, ethylene, propylene, isobutylene, vinyl chloride, styrene, α-methylstyrene, butadiene, and isopentyl Diene, Chloroprene.

Examples of polymerizable macromonomers include those in which the main chain constituent monomer is methyl methacrylate (product name: 45% AA-6 (AA-6S), AA-6; manufactured by Toagosei Co., Ltd. ), a macromonomer whose main chain is butyl acrylate (product name: AB-6; manufactured by Toagosei Co., Ltd.), a macromonomer whose main chain is styrene/acrylonitrile copolymer (product name: AN -6S; manufactured by Toagosei Co., Ltd.).

One kind of other monomers may be used alone, or two or more kinds thereof may be used.

The amount of other monomers used to form a (meth)acrylic copolymer is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less, based on 100% by mass of monomer components used to form a (meth)acrylic copolymer.

The weight average molecular weight (weight average molecular weight, Mw) of the (meth)acrylic copolymer based on the gel permeation chromatography (GPC) method is not particularly limited, but is preferably 100,000 to 1.5 million, more preferably 200,000 to 1.5 million. 1.2 million, more preferably 300,000 to 1 million.

The molecular weight distribution (Mw/Mn) of a (meth)acrylic-type copolymer becomes like this. Preferably it is 20 or less, More preferably, it is 1.5-18, More preferably, it is 1.8-15.

The glass transition temperature (Tg) of the (meth)acrylic copolymer is preferably less than 0°C, more preferably -80 to -10°C, even more preferably -70 to -20°C. The Tg of the (meth)acrylic copolymer can be obtained by Fox's formula, and the Tg of the homopolymer formed from each monomer in the Fox's formula can be the value described in Polymer Handbook Fourth Edition (Wiley-Interscience 2003) .

〔Manufacture of (meth)acrylic copolymer〕

A (meth)acrylic copolymer can be produced by copolymerizing the above-mentioned monomer components, and any of a random copolymer, a block copolymer, and a graft copolymer may be used. For example, the (meth)acrylic copolymer can be produced by a conventionally known polymerization method such as a solution polymerization method, a bulk polymerization method, an emulsion polymerization method, or a suspension polymerization method, and among them, a solution polymerization method is preferable.

Specifically, in the solution polymerization method, other components such as a monomer component, a polymerization initiator, and if necessary, a chain transfer agent and a polymerization solvent are arranged in a reaction vessel, the reaction initiation temperature is set at 40 to 100° C., and the reaction system is maintained at The reaction is carried out for 2 to 20 hours at a temperature of 50 to 90°C. The reaction is performed under an inert gas atmosphere such as nitrogen. In addition, during the polymerization reaction, at least one selected from monomer components, polymerization initiators, chain transfer agents, and polymerization solvents may be additionally added.

As a polymerization initiator, thermal polymerization initiators, such as an azo type initiator and a peroxide type polymerization initiator, are mentioned, for example.

Examples of the azo-based initiator include 2,2'-azobisisobutyronitrile, 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2 , 2'-Azobis(2-cyclopropylpropionitrile), 2,2'-Azobis(2,4-dimethylvaleronitrile), 2,2'-Azobis(2-methylbutyronitrile), 1,1'-Azobis(cyclohexane- 1-formonitrile), 2-(carbamoyl azo) isobutyronitrile, 2-phenylazo-4-methoxy-2,4-dimethylvaleronitrile, 2,2'-azo Bis(2-amidinopropane) dihydrochloride, 2,2'-azobis(N,N'-dimethyleneisobutylamidine), 2,2'-azobis[2-methyl -N-(2-hydroxyethyl)-propionamide], 2,2'-azobis(isobutylamide) dihydrate, 4,4'-azobis(4-cyanovaleric acid ), 2,2'-azobis(2-cyanopropanol), dimethyl-2,2'-azobis(2-methylpropionate) and other azo compounds.

Examples of peroxide-based polymerization initiators include tert-butyl hydroperoxide, cumene hydroperoxide, dicumyl peroxide, benzoyl peroxide, lauryl peroxide, and hexyl peroxide. Di-i-propyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, t-butyl peroxypivalate, 2,2-bis(4,4-di- tert-butylperoxycyclohexyl)propane, 2,2-bis(4,4-di-tert-pentylperoxycyclohexyl)propane, 2,2-bis(4,4-di-tert-octylperoxycyclohexyl)propane Hexyl)propane, 2,2-bis(4,4-di-α-cumylperoxycyclohexyl)propane, 2,2-bis(4,4-di-tert-butylperoxycyclohexyl)butane, 2,2-bis(4,4-di-tert-octylperoxycyclohexyl)butane.

One kind of polymerization initiator may be used alone, or two or more kinds may be used.

In manufacture of a (meth)acrylic-type copolymer, the usage-amount of a polymerization initiator is 0.001-5 mass parts normally with respect to a total of 100 mass parts of monomer components, Preferably it is 0.005-3 mass parts.

Examples of polymerization solvents include aromatic hydrocarbons such as benzene, toluene, and xylene; aliphatic hydrocarbons such as n-pentane, n-hexane, n-heptane, and n-octane; cyclopentane, cyclohexane, and cycloheptane; Alicyclic hydrocarbons such as alkane and cyclooctane; diethyl ether, diisopropyl ether, 1,2-dimethoxyethane, dibutyl ether, tetrahydrofuran, dioxane, anisole, phenyl Ethers such as ethyl ether and diphenyl ether; halogenated hydrocarbons such as chloroform, carbon tetrachloride, 1,2-dichloroethane, chlorobenzene, etc.; ethyl acetate, propyl acetate, butyl acetate, propionic acid Esters such as methyl esters; ketones such as acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, cyclohexanone, etc.; N,N-dimethylformamide, N,N-dimethylformamide Amides such as acetamide and N-methylpyrrolidone; nitriles such as acetonitrile and benzonitrile;

One kind of polymerization solvent may be used alone, or two or more kinds may be used.

〔Tackifying resin〕

The adhesive composition used for the double-sided adhesive sheet of this invention contains tackifying resin. The tackifying resin is not particularly limited as long as it can impart adhesiveness to the adhesive composition. Examples of tackifying resins include styrene-based tackifying resins, rosin-based tackifying resins such as rosin ester-based resins, terpene-based tackifying resins such as terpene-phenol-based resins, and alicyclic saturated hydrocarbon resins.

〔Styrenic Tackifying Resin〕

The styrene-based tackifying resin contained in the adhesive composition is not particularly limited. Examples of styrene-based tackifier resins include styrene-based and substituted styrene-based petroleum resins.

Specific examples of styrene-based tackifying resins include FMR-0150, FTR-0100, FTR-2120, FTR-2140, FTR-6100, FTR-6110, FTR-6125, FTR -7100, FTR-8100, FTR-8120. The above products are manufactured by Mitsui Chemicals Co., Ltd., Japan. Moreover, YS RESIN SX-100 (manufactured by Yasuhara Chemical Co., Ltd.) is also mentioned.

〔Rosin-based tackifying resin〕

The rosin-based tackifying resin contained in the adhesive composition is not particularly limited, and a rosin ester-based tackifying resin is generally used.

Specific examples of rosin ester resins include Super Ester A75, Super Ester A100, Super Ester A115, Super Ester A125, Pinecrystal KE-100, Pinecrystal KE-311, Pinecrystal KE-359, Pinecrystal KE-604, Ester Gum AT, Ester Gum H, Ester Gum HP, PENSEL D-125, PENSEL D-135, PENSEL D-160. The above products are manufactured by ARAKAWA CHEMICAL INDUSTRIES,LTD.

In addition, examples thereof include HARIESTER TF, HARIESTER S, HARITACK 8LJA, HARITACK ER95, HARITACK SE10, HARITACK PH, HARITACK F85, HARITACK F105, HARITACK FK100, and HARITACK PCJ. The above products are manufactured by Harima Chemicals Group, Inc.

〔Terpene Tackifying Resin〕

Examples of terpene-based tackifying resins include YS RESIN PX800, YS RESIN PX1000, YS RESIN PX1150, YS RESIN PX1250, YS POLYSTER U115, YS POLYSTER U130, YS POLYSTER UH115, YS POLYSTER T80, YS POLYSTER T100, YS POLYSTER T115, YS POLYSTER T130, YS POLYSTER T145, YS POLYSTER T160. The above products are manufactured by YASUHARA CHEMICAL CO.,LTD. In addition, Tamanol 803L and Tamanol 901 (manufactured by ARAKAWA CHEMICAL INDUSTRIES, LTD.) are also mentioned.

〔Alicyclic saturated hydrocarbon resin〕

As alicyclic saturated hydrocarbon resin, ARKONP-90, ARKONP-100, ARKONP-115, ARKONP-125, ARKONP-135, ARKONM-90, ARKONM-100, ARKONM-115 are mentioned, for example. The above products are manufactured by ARAKAWA CHEMICAL INDUSTRIES,LTD.

One kind of tackifying resin can be used alone, and two or more kinds can also be used. It is preferred to contain at least one of styrene-based tackifying resin and rosin-based tackifying resin, and it is more preferable to use styrene-based tackifying resin and rosin-based tackifying resin in combination. resin.

In the adhesive composition of the present invention, the tackifying resin is preferably contained in the range of 40 to 70 parts by mass, more preferably 45 to 65 parts by mass, based on 100 parts by mass of the (meth)acrylic copolymer. If it is more than 40 parts by mass, the predetermined strength of the adhesive layer can be obtained, and physical properties such as adhesion force can be exhibited, and if it is less than 70 parts by mass, the uniformity of the adhesive composition can be ensured. When a plurality of tackifying resins are used, the composition of the adhesive composition may be adjusted so that the total amount of the tackifying resins falls within the above range.

The content of the styrene-based tackifying resin when using the styrene-based tackifying resin and the rosin-based tackifying resin in combination is not particularly limited, but is preferably 20 to 38 parts by mass, More preferably, it is 23-35 mass parts, More preferably, it is 27-35 mass parts. More than 20 parts by mass can inhibit the parts from being damaged during re-pasting, and less than 38 parts by mass can uniformly dissolve the styrene-based tackifying resin with poor compatibility in the adhesive composition, and can prevent the resulting adhesive from being damaged. Dullness of the adhesive layer formed by the composition.

In addition, the content of the rosin-based tackifying resin is not particularly limited, but is preferably 18 to 32 parts by mass, more preferably 20 to 30 parts by mass, and even more preferably 26 to 30 parts by mass relative to 100 parts by mass of the (meth)acrylic copolymer. parts by mass. When it is 18 parts by mass or more, strong adhesiveness can be obtained, and when it is less than 32 parts by mass, it is possible to suppress the destruction of parts at the time of re-pasting.

Also, the content of the styrene-based tackifying resin relative to the content of the rosin-based tackifying resin is not particularly limited, but it is preferable that the content of the styrene-based tackifying resin is larger than the content of the rosin-based tackifying resin. When there are more styrene-based tackifying resins than rosin-based tackifying resins, the relationship of adhesion B/adhesion A described below can be easily maintained while maintaining strong adhesiveness.

〔Crosslinking agent〕

The crosslinking agent contained in the adhesive composition is a substance reactive to the crosslinkable group contained in the (meth)acrylic copolymer.

As a crosslinking agent, an isocyanate, an epoxy compound, and a metal chelate compound are mentioned, for example.

As the isocyanate, an isocyanate having two or more isocyanate groups in one molecule is usually used, preferably 2 to 8, and more preferably 3 to 6. When the number of isocyanate groups is within the above-mentioned range, it is preferable from the viewpoint of the efficiency of the crosslinking reaction between the (meth)acrylic copolymer and isocyanate and maintaining the flexibility of the adhesive layer.

Examples of the diisocyanate having two isocyanate groups in one molecule include aliphatic diisocyanate, alicyclic diisocyanate, and aromatic diisocyanate. Examples of aliphatic diisocyanate include ethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 2-methyl-1,5-pentane diisocyanate, 3- Aliphatic diisocyanates having 4 to 30 carbon atoms such as methyl-1,5-pentane diisocyanate and 2,2,4-trimethyl-1,6-hexamethylene diisocyanate. Examples of the alicyclic diisocyanate include isophorone diisocyanate, cyclopentyl diisocyanate, cyclohexyl diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated diphenylene diisocyanate, and hydrogenated diphenylene diisocyanate. C7-30 alicyclic diisocyanates such as methane diisocyanate and hydrogenated tetramethylxylene diisocyanate. Examples of the aromatic diisocyanate include phenylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate, naphthalene diisocyanate, diphenyl ether diisocyanate, and diphenylmethane diisocyanate. , diphenylpropane diisocyanate and other aromatic diisocyanates with 8 to 30 carbon atoms.

Examples of the isocyanate having three or more isocyanate groups in one molecule include aromatic polyisocyanate, aliphatic polyisocyanate, and alicyclic polyisocyanate. Specifically, 2, 4,6-triisocyanate toluene, 1,3,5-triisocyanate benzene, 4,4’,4”-triphenylmethane triisocyanate.

In addition, as the isocyanate, for example, the above-mentioned isocyanate having 2 or 3 or more isocyanate groups, a multimer (such as a dimer or a trimer, a biuret body, an isocyanurate body), derivatives ( For example, an addition reaction product of a polyol and two or more molecules of diisocyanate), and a polymer. As the polyhydric alcohol in the above-mentioned derivatives, for example, trimethylolpropane, glycerin, pentaerythritol and other trivalent or higher alcohols can be mentioned as low molecular weight polyols; for example, polyether polyols, Polyester polyol, acrylic polyol, polybutadiene polyol, polyisoprene polyol.

As such an isocyanate, for example, a trimer of diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, hexamethylene diisocyanate, or a biuret body of tolylene diisocyanate or Isocyanurate bodies, reaction products of trimethylolpropane and tolylene diisocyanate or xylylene diisocyanate (such as tolylene diisocyanate or xylylene diisocyanate 3-molecule adduct), reaction product of trimethylolpropane and hexamethylene diisocyanate (for example, 3-molecule adduct of hexamethylene diisocyanate), polyether polyisocyanate, polyester polyisocyanate.

Among isocyanates, xylylene diisocyanate-based and hexamethylene diisocyanate-based cross-linking agents are preferred in terms of yellowing resistance, and tolylene diisocyanate-based cross-linking agents are preferred from the viewpoint of stress relaxation. joint agent. As a xylylene diisocyanate-based crosslinking agent, such as Examples include xylylene diisocyanate and its multimers, derivatives, and polymers; examples of hexamethylene diisocyanate-based crosslinking agents include hexamethylene diisocyanate and its multimers, Derivatives and polymers; Examples of tolylene diisocyanate-based crosslinking agents include tolylene diisocyanate, multimers, derivatives, and polymers thereof.

Examples of the epoxy compound include compounds having two or more epoxy groups in the molecule, for example, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin Triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, diglycidyl aniline, N,N,N',N'-tetraglycidyl-m-benzenedi Methylenediamine, 1,3-bis(N,N'-diamineglycidylaminomethyl)cyclohexane, 1,3-bis(N,N-diglycidylaminomethyl)benzene.

As the metal chelate compound, for example, polyvalent metal complex alkoxides, acetylacetone, acetoacetone, etc. Compounds such as ethyl acyl acetate. Specifically, aluminum isopropoxide, aluminum sec-butoxide, ethylaluminum diisopropyl acetylacetate, tris(ethylacetylacetate)aluminum, and aluminum triacetylacetonate are exemplified.

One type of crosslinking agent may be used alone, or two or more types may be used.

The adhesive composition of the present invention preferably contains 0.01 to 5 parts by mass, more preferably 0.05 to 3 parts by mass, and still more preferably 1 to 2.5 parts by mass, based on 100 parts by mass of the (meth)acrylic copolymer. the cross-linking agent. With such a form, excellent adhesion properties can be realized.

〔additive〕

The adhesive composition used in the double-sided adhesive sheet of the present invention may contain silane coupling agents, polymeric organosiloxane compounds, pigments, flame retardants, plasticizers, antistatic agents, lubricants, fillers, etc. Various additives. The content of the additives is not particularly limited, but should be within a range that does not inhibit the properties of the double-sided adhesive sheet and the adhesive composition used for the double-sided adhesive sheet of the present invention.

〔Organic solvents〕

The adhesive composition used in the double-sided adhesive sheet of the present invention may contain an organic solvent in order to adjust applicability. As an organic solvent, the polymerization solvent demonstrated in the part of the manufacturing conditions of a (meth)acryl-type copolymer is mentioned, for example. The content of the organic solvent in the adhesive composition is usually 30 to 90% by mass, preferably 40 to 90% by mass.

〔Adhesive composition〕

The adhesive composition used for the double-sided adhesive sheet of the present invention contains 40 to 65 parts by mass of tackifier resin and 0.01 to 5 parts by mass of crosslinking agent per 100 parts by mass of (meth)acrylic copolymer , can be prepared by mixing these. It should be noted that the adhesive composition may contain other components.

〔Double-sided adhesive sheet〕

The double-sided adhesive sheet of the present invention is composed of a core material and adhesive layers (first adhesive layer and second adhesive layer) formed on both sides of the core material. Therefore, the double-sided adhesive sheet of the present invention has at least 3 layers Structure. In addition, a release film may be attached to the surface of the adhesive layer that is not in contact with the core material.

〔Core〕

The double-sided adhesive sheet of the present invention contains a core material. The core material used in the double-sided adhesive sheet of the present invention has a thickness of 1 to 12 μm. If it is more than 1 μm, suitable sheet strength can be obtained, and if it is less than 12 μm, excessive adhesion can be suppressed.

Examples of the core material and release film include polycarbonate (PC), polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polybutylene terephthalate ( PBT), polyethylene naphthalate (PEN), polyethylene (PE), polypropylene (PP), ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, acrylonitrile-butadiene-styrene Plastic film of copolymer (ABS), polyamide (nylon), polyimide, polyvinyl chloride (PVC), etc. Moreover, glass, paper, a nonwoven fabric, etc. are mentioned as a core material. It should be noted that the core material is preferably PET from the viewpoint of strength and ease of handling.

When the double-sided adhesive sheet of the present invention is used as a light-shielding tape, a core material in which a black color material such as a black pigment or a white color material such as a white pigment is dispersed can be used.

〔Adhesive layer〕

The adhesive layer provided on both sides of the core material may be formed from an adhesive composition. The adhesive layers on both sides of the core material may be the same or different.

A single adhesive layer has a thickness of 1-12 μm. A double-sided adhesive sheet with a suitable adhesive force can be obtained if it is more than 1 μm, and excessive adhesion can be suppressed if it is less than 12 μm.

In addition, from the viewpoint of cohesive force, adhesive force described later, and suitability for re-pasting, the gel fraction of the adhesive layer is preferably 10 to 98% by mass, more preferably 20 to 90% by mass, and even more preferably 30 to 85% by mass. .

〔Adhesion A〕

The double-sided adhesive sheet of the present invention is characterized in that the adhesive force A measured after attaching the adhesive surface of the adhesive layer to the SUS plate and leaving it for 20 minutes in an environment of 25°C/50%RH is 1000 to 1600g/ 25mm. Having such a feature means that it belongs to a double-sided adhesive sheet with strong initial adhesion. Detailed measurement conditions are described in Examples.

[Adhesion B/Adhesion A]

The double-sided adhesive sheet of the present invention is characterized in that when the adhesive force B is measured after the adhesive surface of the adhesive layer is attached to the SUS plate and left in an environment of 25°C/50%RH for 24 hours, The ratio of the adhesive force B to the aforementioned adhesive force A (adhesive force B/adhesive force A) is 1.00˜1.25. The measurement conditions of the adhesive force B are described in Examples.

Adhesion B is the adhesive force measured after 24 hours of sticking, and it is usually higher than that of Adhesion A. However, since the adhesive force B/adhesive force A of the double-sided adhesive sheet of the present invention is not less than 1.00 and not more than 1.25, the increase rate of the adhesive force is not high, and excessive adhesion can be suppressed. That is, the double-sided adhesive sheet of the present invention has high re-adhesive properties, and can suppress damage to components due to re-adhesive.

〔use〕

As described above, the double-sided adhesive sheet of the present invention is both a thin film and strong adhesiveness, and suppresses over-adhesion, imparts re-adhesive suitability, and can be used for various purposes. For example, a heat sink or a light-shielding tape can be attached to a target article using the double-sided adhesive sheet of the present invention. The heat sink and light-shielding tape are explained below.

heat sink

By providing heat sinks in local high-temperature parts, heat can be dissipated over the entire surface of OA equipment and electronic equipment. As a graphite sheet used for a heat radiation sheet, the natural graphite sheet obtained by flaking natural graphite powder, the artificial graphite sheet obtained by heat-processing a polymer film, etc. are mentioned, for example.

Examples of the above polymer film include polyimide, polyamide, polyoxadiazole, polybenzothiazole, polybenzobithiazole, polybenzoxazole, polybenzobisoxazole, poly Films composed of p-phenylene vinylene, polybenzimidazole, polybenzobisimidazole, polythiazole, etc.

The thickness of the graphite sheet is preferably 10 to 100 μm, more preferably 15 to 50 μm. By setting the thickness of the graphite sheet into the above-mentioned range, it can be suitably used for component fixing of OA equipment and electronic equipment.

blackout tape

For example, by using a light-shielding tape for laminating a non-self-luminous display unit such as a liquid crystal display module unit and a backlight unit, problems due to light leakage can be prevented.

[Manufacturing method of double-sided adhesive sheet]

The double-sided adhesive sheet of the present invention can be produced as follows.

The adhesive composition is applied to one side of the release film so that the thickness after drying becomes 1 to 12 μm, and the solvent is removed by drying at usually 60 to 100° C. for 1 to 10 minutes. Thereafter, the obtained adhesive layer was bonded to one side of the core material with a thickness of 1-12 μm (the first surface of the core material).

Next, the adhesive composition is applied on one side of another release film so that the thickness after drying becomes 1 to 12 μm. Further, dry at 60-100° C. for 1-10 minutes to remove the solvent, and attach the adhesive layer thus obtained to the side of the above-mentioned core material on which the adhesive layer is not attached (the second surface of the core material). , thus producing a double-sided adhesive sheet.

The coating method is not particularly limited, and conventionally known methods can be used. Examples of coating methods for the adhesive composition include roll coaters, spray blade coaters, lip coaters, blade coaters, die coaters, transfer coaters, reverse coaters, curtain coaters, etc. A method such as a type coater, a slit coater, or the like.

Wherein, the adhesive layer formed on the first surface and the adhesive layer formed on the second surface may be the same or different.

【Example】

Examples are described below, but the present invention is not limited by the Examples.

(Manufacturing example: Preparation of adhesive composition)

97 parts by mass of n-BA (n-butyl acrylate), 2 parts by mass of AA (acrylic acid), 2HEA (2-hydroxyethyl acrylate ) 1 mass part, 80 mass parts of ethyl acetate, while introducing nitrogen, the temperature is raised to 75°C. Next, 0.3 parts by mass of azobisisobutyronitrile was added, and the reaction was performed for 4 hours by repeating heating and cooling so that the temperature of the content in the flask was maintained at 75 to 76°C. After completion of the reaction, 20 parts by mass of ethyl acetate was further added to obtain a (meth)acrylic copolymer having a weight average molecular weight (Mw) of 850,000.

35 parts by mass of a styrene-based tackifying resin (FTR-6100: manufactured by Mitsui Chemicals Co., Ltd.), rosin-based tackifying resin (D-135 : ARAKAWA CHEMICAL INDUSTRIES, LTD.) 30 mass parts, an isocyanate crosslinking agent (L-45: Soken Chemical Co., Ltd.) 1.5 mass parts (solid content), and the adhesive composition was obtained.

(Example 1: double-sided adhesive sheet and its manufacture)

Apply the adhesive composition to a peeling film so that the thickness after drying becomes 5 μm, dry at 90° C. for 3 minutes, and stick to a PET film (core material) with a thickness of 2 μm (adhesive layer on the first side) Formation). Furthermore, the adhesive composition was applied on a release film so that the thickness after drying became 5 μm, dried at 90° C. for 3 minutes, and the obtained adhesive layer-attached sheet was bonded to the PET film. The side of the first-side adhesive layer that is not bonded (formation of the second-side adhesive layer) was used to make a double-sided adhesive sheet (Example 1).

(Examples 2-6 and Comparative Examples 1-3)

Various double-sided adhesive sheets were obtained in the same manner as in Example 1 (Examples 2 to 6 and Comparative Example 1) except that the amount of tackifying resin used and the thicknesses of the core material and the adhesive layer were changed to those described in Table 1. ~3).

<Measurement‧Evaluation>

The measurement conditions of the weight average molecular weight of the (meth)acrylic-type copolymer used in Examples 1-6 and Comparative Examples 1-3, adhesive force A, and adhesive force B are as shown.

(weight average molecular weight (Mw))

About the (meth)acrylic-type copolymer, the weight average molecular weight (Mw) based on standard polystyrene conversion was calculated|required by the gel permeation chromatography (GPC) method under the following conditions.

‧Measuring device: HLC-8120GPC (manufactured by Tosoh Corporation)

‧GPC column composition: the following 5 columns (all manufactured by Tosoh Corporation)

(1) TSK-GEL HXL-H (guard column)

(2) TSK-GEL G7000HXL

(3) TSK-GEL GMHXL

(4) TSK-GEL GMHXL

(5) TSK-GEL G2500HXL

‧Sample concentration: diluted with THF to 1.0mg/cm ³

‧Mobile phase solvent: tetrahydrofuran

‧Flow rate: 1.0cm3/min

‧Column temperature: 40℃

(Adhesion A and Adhesion B)

The release film on the first adhesive layer side of the double-sided adhesive sheets obtained in Examples and Comparative Examples was peeled off, and the entire surface of the exposed adhesive layer was attached to a PET film with a thickness of 50 μm, and cut into 25 mm ×150mm, and produced a test piece. Next, the release film on the side of the second adhesive layer was peeled off to bond the exposed adhesive layer to the SUS plate, and a roller weighing 2 kg was reciprocated three times for pressure bonding. After being crimped and placed in an environment of 25°C/50%RH for 20 minutes, the end of the test piece was pulled at a speed of 300 mm/min in a direction 180° relative to the PET film surface, and the adhesion A was measured.

In addition, the adhesive force B was measured in the same manner as that of the adhesive force A, except that it was left to stand in a 25° C./50% RH environment for 24 hours after crimping.

The double-sided adhesive sheets of the examples were both films and had high initial adhesion, and excessive adhesion was suppressed, indicating that they were excellent in re-adhesion suitability. The double-sided adhesive sheets of Comparative Example 1 in which the amount of tackifier resin used was less than 40 parts by mass and Comparative Example 2 in which the thickness of the core material exceeded 12 μm resulted in low initial adhesion, while the comparison of the adhesive layer thickness exceeding 12 μm The double-sided adhesive sheet of Example 3 was the result of failure to suppress excessive adhesion.

Claims (6)

A double-sided adhesive sheet, wherein, it is a double-sided adhesive sheet with an adhesive layer on both sides of the core material, and the adhesive layer is composed of 100 parts by mass of (meth)acrylic copolymer, styrene An adhesive composition consisting of 23-35 parts by mass of tackifying resin, 18-32 parts by mass of rosin-based tackifying resin and 0.01-5 parts by mass of crosslinking agent, wherein the thickness of the core material is 1-12 μm, The thickness of the adhesive layer on both sides of the core material is 1-12 μm respectively, and the following conditions (i) and (ii) are satisfied: (i) the adhesive layer is The adhesive surface is attached to the SUS plate and the adhesion force A measured after placing it in an environment of 25°C/50%RH for 20 minutes is 1000~1600g/25mm; (ii) the adhesive surface of the adhesive layer is attached to When the adhesive force measured after the SUS board was left standing for 24 hours in an environment of 25°C/50%RH was regarded as the adhesive force B, the value of the adhesive force B/adhesive force A was 1.00 to 1.25. The double-sided adhesive sheet according to claim 1, wherein the content of the styrene-based tackifying resin is greater than the content of the rosin-based tackifying resin. The double-sided adhesive sheet according to claim 2, wherein the content of the styrene-based tackifying resin is 27-35 parts by mass, and the content of the rosin-based tackifying resin is 26-30 parts by mass. The double-sided adhesive sheet according to claim 1, wherein the content of the styrene-based tackifying resin is 27-35 parts by mass, and the content of the rosin-based tackifying resin is 26-30 parts by mass. The double-sided adhesive sheet according to any one of claims 1 to 4 is a double-sided adhesive sheet for heat sinks. The double-sided adhesive sheet according to any one of Claims 1 to 4 is a double-sided adhesive sheet for light-shielding tape.