JP2001279196A - Substrate-free, thermally conductive pressure-sensitive adhesive tape or sheet and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate-free thermally conductive pressure-sensitive adhesive tape or sheet that is good in basic adhesive properties such as adhesive force, retention force at high temperatures, or the like, and is excellent in thermal conductivity. SOLUTION: This substrate-free, thermally conductive pressure-sensitive adhesive tape or sheet is produced by using a photocurable, thermally conductive pressure-sensitive adhesive comprising as main components an alkyl (meth) acrylate monomer, a polar group-containing monomer, an acrylic polymer having a photoactive functional group, a photopolymerization initiator and thermally conductive particles and polymerizing the adhesive by light irradiation, wherein the acrylic polymer having a photoactive functional group has a weight average molecular weight of 200,000-3,000,000 and the content of the photoactive functional group is 0.001-0.5 milliequivalent/g and wherein the content of the thermally good conductive material is 10-300 pts.wt. per 100 pts.wt. photocurable pressure-sensitive adhesive in the photocurable, thermally conductive pressure- sensitive adhesive.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acrylic-based heat-conductive pressure-sensitive adhesive tape / sheet and a method for producing the same.

[0002]

2. Description of the Related Art With the high integration, high performance, high functionality, and miniaturization of computers and communication devices, printed wiring boards and ceramic module substrates used in these electronic devices are also becoming highly integrated. It is downsized. For this reason, measures to dissipate heat from various electric and electronic devices have become increasingly important, and fixing of these printed wiring boards and ceramic module boards to heat sinks and heat dissipation fins has traditionally required a heat conductive adhesive or heat sink. Joining with conductive silicone rubber or the like has been performed.

In recent years, in industries such as the electric and electronic fields, products have been remarkably reduced in size, weight, and integration, and accordingly, adhesives and pressure-sensitive adhesives used for joining parts have high heat resistance. Demands for high adhesion, high reliability, etc. are increasing. In particular, from the viewpoint of improving workability and work environment, various components are joined using a tape-shaped or sheet-shaped pressure-sensitive adhesive ("pressure-sensitive adhesive" is referred to as "adhesion") instead of the liquid adhesive. Things are increasing. Also in the field of heat radiation fixing of various electronic components described above, development of a heat conductive adhesive tape having good heat conductivity and easy adhesion such as an adhesive tape is desired. Above all, with the miniaturization of components and equipment, the demand for thinning is strict, and in order to improve the adhesion with the adherend, it has the characteristics described above,
In addition, there is a demand for the development of a flexible, non-substrate thermally conductive pressure-sensitive adhesive tape / sheet that does not use a support.

[0004] As the heat conductive adhesive tape, there are (1) a case where conductivity is required together with heat conductivity, and (2) a case where electrical insulation is required together with heat conductivity.

[0005] In the case of the above (1), a heat conductive adhesive obtained by dispersing heat conductive particles such as metal powder in an adhesive material has been coated on a heat conductive base material such as a metal foil. Engineered ones are being considered. As the heat conductive substrate,
Metal foils such as copper foils, aluminum foils, stainless steel foils, nickel foils, and plastic films or nonwoven fabrics on which metals are deposited or plated are used. In the case of producing a heat-conductive double-sided pressure-sensitive adhesive tape, one obtained by applying the above-mentioned heat-conductive pressure-sensitive adhesive on both surfaces of the above-mentioned heat-conductive base material is used.

In the case of the above (2), a heat conductive pressure-sensitive adhesive obtained by dispersing heat conductive particles having electrical insulation properties such as metal oxides, metal nitrides, and metal borides in a pressure-sensitive adhesive substance is used. Heat conductive adhesive tapes coated on an electrically insulating substrate made of a plastic film or the like have been studied.

However, in the heat conductive adhesive tape having such a base material which has been conventionally studied, the thickness of the adhesive tape is increased and the adhesive tape is hardened. As a result, the adhesiveness to the adherend is increased. Has a problem. In addition, it is not possible to cope with miniaturization required for joining electric and electronic components, and a solution is desired.

[0008] Conventionally, as a method for producing an adhesive tape, a water-based adhesive such as a solvent-type adhesive or an emulsion is applied onto a substrate, and then the solvent or water is volatilized by heating to crosslink the adhesive. , Curing methods have been adopted.

However, solvent-based pressure-sensitive adhesive tapes which have been conventionally used and which are cured by heating have problems in heat resistance and reliability after bonding.
No. 784, Japanese Unexamined Patent Publication No. 9-137142 and the like have developed ultraviolet-curable pressure-sensitive adhesive tapes.

[0010]

However, even in the ultraviolet-curable pressure-sensitive adhesive tape described in the above publication,
If the thickness of the adhesive tape is small, it is difficult to obtain a non-base heat conductive adhesive tape having good adhesive basic properties such as adhesive strength and high-temperature holding power, and also having excellent thermal conductivity. The development of materials and processes for solving the problem was desired.

An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a non-substrate having good basic adhesive properties such as adhesive strength and high-temperature holding power and excellent thermal conductivity. An object of the present invention is to provide a heat conductive adhesive tape / sheet and a method for producing the same.

[0012]

In order to achieve the above object, the present invention provides an alkyl (meth) acrylate monomer, a polar group-containing monomer, and an acrylic high molecular weight having a photoactive functional group. Non-base prepared using a photocurable heat-conductive adhesive in which a metal powder, a metal oxide, and other good heat-conductive materials are dispersed in a photocurable pressure-sensitive adhesive whose main component is a polymer and a photopolymerization initiator In the heat conductive pressure-sensitive adhesive tape / sheet, the weight average molecular weight of the acrylic polymer having a photoactive functional group is 200,000 to 3,000,000, and the content of the photoactive functional group is 0.001 to 0.5 mm. Equivalent / g, and the content of the good heat conductive substance with respect to 100 parts by weight of the photo-curable pressure-sensitive adhesive is 10 to 300 parts by weight.

In the method for producing a heat-conductive adhesive tape / sheet without a base material, the photo-curable heat-conductive pressure-sensitive adhesive is coated on a sheet substrate to a thickness of 5 to 500 μm to form a photo-curable pressure-sensitive adhesive tape / sheet. A heat conductive adhesive layer is formed, and the photocurable heat conductive adhesive layer is cured by light irradiation.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION In order to achieve the above object, the present inventors examined various materials and processes, and found that a (meth) acrylic acid alkyl ester monomer, a polar group-containing monomer and a photoactive functional group were used. (1) In the case where the photocurable pressure-sensitive adhesive mainly composed of an acrylic high-molecular-weight material and a photopolymerization initiator having a conductivity is also required, conductive heat-conductive particles such as metal powder (2) In the case where electric insulation is required by using a heat conductive photo-curable pressure-sensitive adhesive in which is dispersed heat-dispersible heat conductive particles such as metal oxides. Non-substrate thermally conductive adhesive tapes / sheets produced by polymerizing by light irradiation using a conductive photo-curing adhesive have good adhesive properties such as adhesive strength and high-temperature holding power even when the tape thickness is small. It was confirmed that the heat conductivity was excellent.

The acrylic high molecular weight material having a photoactive functional group used here has a weight average molecular weight of 200,000 to 3,000,000 and a photoactive functional group content of 0.001 to 0,0. It was found that a material having a weight of 5 meq / g was good, and a non-substrate thermal conductivity prepared using a heat-conductive photocurable pressure-sensitive adhesive obtained by dispersing heat-conductive particles in a photocurable pressure-sensitive adhesive containing the same. It was confirmed that the pressure-sensitive adhesive tape / sheet exhibited excellent properties such as adhesive strength, high-temperature holding power, and thermal conductivity.

That is, by using the non-base heat conductive adhesive tape / sheet made of the heat conductive light-curable pressure-sensitive adhesive of the present invention, the basic adhesive properties such as adhesive strength and high-temperature holding power and good thermal conductivity are obtained. Is obtained. In addition, the thickness of the adhesive tape / sheet can be reduced, and since there is no base material, the adhesiveness to the adherend is excellent, and it is possible to obtain a heat-dissipating joint suitable for small electric / electronic parts. it can.

The materials used in the present invention and the method for producing the pressure-sensitive adhesive tape / sheet will be described below.

The acrylic high molecular weight material having a photoactive functional group is used for improving the heat resistance of the pressure-sensitive adhesive tape / sheet, particularly the characteristics such as high-temperature holding power, and the workability such as coating property. Used to improve
The acrylic high molecular weight material having a photoactive functional group used in the present invention has a weight average molecular weight of 200,000 to 300.
Acrylic high molecular weight materials having a photoactive functional group content of 0.001 to 0.5 meq / g are preferred.

As a method for introducing the photoactive functional group into the acrylic high molecular weight compound, an isocyanate compound having a (meth) acryloyloxy group having a hydroxyl group on the side chain of the acrylic high molecular weight compound (for example, 2 -Methacryloyloxyethyl isocyanate). In this way, an acrylic high molecular weight substance having a photoactive functional group such as a (meth) acryloyloxy group can be obtained. However, the introduction method is not particularly limited.

When the weight average molecular weight of the above-mentioned acrylic high molecular weight compound having a photoactive functional group is less than 200,000,
In order to obtain a high-viscosity adhesive composition of several thousand to several tens of thousands cp in consideration of coatability and the like, it is necessary to increase the amount of the acrylic polymer having a photoactive functional group. As a result, the adhesive tape has both excellent adhesive properties (specifically, adhesive strength of 3.5N / 10mm or more to a stainless steel substrate) and heat resistance (specifically, holding power at 150 ° C or more). No, not preferred. Further, when the weight average molecular weight is 30
If it is larger than 0,000, there is no particular problem in the properties of the pressure-sensitive adhesive tape, but it is difficult to mass-produce an acrylic high molecular weight substance, which is not preferable.

When the content of the photoactive functional group of the acrylic polymer having a photoactive functional group is less than 0.001 meq / g, the high-temperature holding power of the pressure-sensitive adhesive tape deteriorates. When the content of the photoactive functional group is more than 0.5 meq / g, the adhesive strength of the pressure-sensitive adhesive tape becomes low, which is not preferable in any case. The amount of the acrylic polymer having a photoactive functional group in the pressure-sensitive adhesive composition is adjusted according to the desired pressure-sensitive adhesive properties and the viscosity at the time of coating. 5-
Used at 50% by weight.

The main component of the acrylic polymer having a photoactive functional group is usually a copolymer of a (meth) acrylic acid alkyl ester monomer and a polar group-containing monomer, for example, an acrylic polymer. Copolymers of 2-ethylhexyl acrylate and 2-hydroxyethyl methacrylate, terpolymers of isooctyl acrylate, acrylic acid and 2-hydroxyethyl methacrylate, and the like are used, but are not particularly limited thereto. Not something.

The alkyl (meth) acrylate monomers used in the present invention include, for example, ethyl, propyl, butyl, pentyl, hexyl, 2-ethylhexyl, octyl, Usually, esters of (meth) acrylic acid having an alkyl group having 20 or less carbon atoms, such as an isooctyl group, a nonyl group, an isononyl group, and a decyl group, are exemplified. The above-mentioned alkyl (meth) acrylate is used alone or in combination of two or more. In the present invention,
Part of the alkyl (meth) acrylate may be replaced with a copolymerizable monomer such as vinyl acetate.

Examples of the polar group-containing monomer used in the present invention include acrylic acid, methacrylic acid, itaconic acid, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, dimethylaminoethyl acrylate, acrylonitrile, methacrylic acid and the like. Ronitrile, N-vinyl-2
-Polymerizable unsaturated monomers having a polar group such as a carboxyl group, a hydroxyl group or an amino group in the molecule, such as pyrrolidone.

The compounding amount is from 1 to 3 with respect to 99 to 70 parts by weight of the above-mentioned alkyl (meth) acrylate.
It is preferably 0 parts by weight. When the content of the polar group-containing monomer is less than 1 part by weight, the adhesive strength of the pressure-sensitive adhesive tape is reduced, and when the content is more than 30 parts by weight, the adhesive property of the pressure-sensitive adhesive tape at low temperatures is reduced, Either case is not preferred. The polar group-containing monomers described above are used alone or in combination of two or more.

As the above-mentioned photopolymerization initiator, a usual photopolymerization initiator used for radical photopolymerization such as a vinyl group or a (meth) acryloyloxy group is used. For example,
2,2-dimethoxy-1,2-diphenylethane-1-
Benzyldimethyl ketal compounds such as ON (Irgacure 651 from Ciba Specialty Chemicals), 1-hydroxycyclohexyl phenyl ketone (Irgacure 18 from Ciba Specialty Chemicals)
4), α-hydroxyketone compounds such as 2-hydroxy-2-methyl-1-phenylpropan-1-one (Darocur 1173 of Ciba Specialty Chemicals), 2-benzyl-2-dimethylamino-1- (4
Α-aminoketone compounds such as -morpholinophenyl) butanone-1 (Irgacure 369 from Ciba Specialty Chemicals) and bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide (Ciba Specialty Chemicals) Irgacure 81
9) and the like, and bis (2,6-dimethoxybenzoyl) -2,4,
Bisacylphosphine oxides such as 4-trimethylpentylphosphine oxide and Darocure 117
1: 3 mixture of Irgacure 1700 with Ciba Specialty Chemicals, bisacylphosphine oxide such as bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide and Irgacure 184 1: 1 mixture with Irgacure 185 (Ciba Specialty Chemicals)
0), benzoin ethyl ether compounds such as benzoin ethyl ether and benzoin isopropyl ether. In particular, a photopolymerization initiator such as a bisacylphosphine oxide-based compound that generates two or more active species (radicals) from one molecule of the photopolymerization initiator by light irradiation is desirable.

These photopolymerization initiators are preferably used in a ratio of 0.001 to 5 parts by weight based on 100 parts by weight of the photocurable pressure-sensitive adhesive. When the amount is less than 0.001 part by weight, it is difficult to complete the polymerization sufficiently, and when the amount is more than 5 parts by weight,
The molecular weight of the resulting pressure-sensitive adhesive polymer is reduced, and particularly, the holding power of the pressure-sensitive adhesive tape at high temperatures is lowered, which is not preferable in terms of pressure-sensitive adhesive properties.

As the heat conductive substance used in the present invention, when conductivity is required, nickel powder, copper powder, silver powder, aluminum powder, iron powder, titanium powder, alloy powder of these metals, etc. Conductive and heat conductive particles can be mentioned, and when electrical insulation is required, metal oxides (for example, Al ₂ O
₃ , SiO ₂ , TiO ₂ , MgO, NiO, Fe
₂ O ₃ , CuO, etc.) powder, metal nitride (for example, BN,
Electrically insulating and thermally conductive particles such as Si ₃ N ₄ powder, metal boride (eg, TiB ₂ ) powder, and metal carbide (eg, SiC) powder.

In order to obtain high thermal conductivity with a small amount of the thermally conductive particles added, it is preferable to use a secondary aggregate of the thermally conductive particles. Further, in order to prevent sedimentation of the thermally conductive particles, various anti-settling agents (for example, Disparon # 6650 manufactured by Kusumoto Kasei) may be added.

These heat conductive particles are preferably used in a proportion of 10 to 300 parts by weight based on 100 parts by weight of the photocurable pressure-sensitive adhesive. If the amount is less than 10 parts by weight, it is difficult to sufficiently exhibit heat conductivity, and if the amount is more than 300 parts by weight, it is difficult to obtain sufficient adhesive strength, In any case, it is not practically preferable as a non-base heat conductive adhesive tape / sheet.

The photocurable heat conductive pressure-sensitive adhesive of the present invention may further comprise, if necessary, a pressure-sensitive adhesive composition 100 excluding heat conductive particles.
About 0.001 to 5 parts by weight of a photopolymerizable compound such as a polyfunctional acrylic (methacrylic) monomer may be added to the parts by weight. Examples of such a photopolymerizable compound include hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, and dipentaerothritol hexa. Examples include (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, epoxy acrylate, polyester acrylate, urethane acrylate, and the like.

The photocurable heat-conductive pressure-sensitive adhesive for producing the substrate-free heat-conductive pressure-sensitive adhesive tape / sheet of the present invention includes rosin-based resins, terpene-based resins, and A tackifier such as a resin may be added.

Further, the photo-curing type heat conductive pressure-sensitive adhesive of the present invention may contain commonly used compounding agents such as a thickener, a thixotropic agent and a filler. Examples of the thickener include acrylic rubber and epichlorohydrin rubber, and examples of the thixotropic agent include ultrafine silica (Aerosil 300 manufactured by Aerosil Japan). As the filler, calcium carbonate, titanium dioxide, inorganic particles such as silicon dioxide, nylon beads, acrylic beads, organic particles such as silicone beads, glass balloon,
Examples include inorganic hollow particles such as alumina balloons, organic hollow particles such as acrylic balloons and vinylidene chloride balloons, and organic or inorganic short fibers such as polyester, nylon, rayon, and glass. These are added in order to improve mechanical properties such as stress relaxation of the pressure-sensitive adhesive tape / sheet, and are used within a range that does not impair photocurability and the like.

The above-mentioned photocurable heat conductive pressure-sensitive adhesive is in a liquid state, and is coated on a sheet substrate such as a polyester film subjected to a release treatment by a roll coater or a die coater, and then polymerized by light irradiation. Thereby, a base material-free heat conductive adhesive tape / sheet is obtained. When the photocurable heat conductive pressure sensitive adhesive is polymerized, the polymerization reaction is inhibited by oxygen in the air or oxygen dissolved in the pressure sensitive adhesive. Light irradiation is performed in an atmosphere replaced with an inert gas such as A tin salt compound having a deoxidizing effect, such as stannous octoate or triisodecyl phosphite, or a phosphorus-based compound may be added to suppress the inhibition of curing by oxygen.

Hereinafter, the method for producing the heat-resistant pressure-sensitive adhesive tape / sheet of the present invention will be described in detail. However, the thermally conductive pressure-sensitive adhesive tape / sheet of the present invention is not limited to those manufactured by this method.

First, the (meth) acrylic acid alkyl ester monomer and the polar group-containing monomer are mixed in a predetermined blending amount, and the acrylic high molecular weight material having a photoactive functional group Predetermined amounts of the conductive particles and the photopolymerization initiator are added, sufficiently stirred and mixed to obtain a uniform heat-conductive pressure-sensitive adhesive dispersion. At this time, the viscosity at 25 ° C. of the heat conductive adhesive dispersion is preferably 1,000 to 50,000 cp in terms of coating. The viscosity is adjusted according to the thickness required for the tape sheet.

If necessary, the above-mentioned polyfunctional (meth) acrylic monomer, thixotropic agent, filler and the like may be added to the above-mentioned heat conductive adhesive dispersion. The heat conductive pressure-sensitive adhesive dispersion thus prepared is applied to a predetermined thickness of usually 5 to 500 μm on a sheet substrate such as a polyester film subjected to a release treatment. Next, under a nitrogen atmosphere or under a condition in which a transparent polyester-coated film is overlaid and the air is shut off, the UV intensity at 365 nm is about 0.1 to 1 using a black light.
An ultraviolet ray of 0 mW / cm ² is irradiated for 20 seconds to 5 minutes to cure the heat conductive pressure-sensitive adhesive layer, thereby obtaining a substrate-free heat conductive pressure-sensitive adhesive tape sheet.

[0038] The base material-free thermally conductive pressure-sensitive adhesive tape sheet of the present invention is obtained in this manner.
When bonded to an adherend such as an electronic component, it exhibits excellent adhesive properties and thermal conductivity.

[0039]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The non-substrate thermally conductive pressure-sensitive adhesive tape / sheet of the present invention and the method for producing the same will be specifically described with reference to the embodiments of the present invention. However, the non-substrate thermally conductive pressure-sensitive adhesive tape / sheet of the present invention and the method for producing the same are not limited thereto. It should be noted that “parts” in the description of the examples and comparative examples of the embodiments represents parts by weight. Example 1 2-Ethylhexyl acrylate having a weight average molecular weight of 700,000 and a photoactive functional group content of 0.01 meq / g was used as a main component in 63 parts of 2-ethylhexyl acrylate and 7 parts of acrylic acid. Acrylic high molecular weight body 30
Parts, 1,6-hexanediol diacrylate 0.05
Parts, 100 parts of α-alumina powder (average particle size: 2 μm) and 0.3 parts of a photopolymerization initiator Irgacure 819 (manufactured by Ciba Specialty Chemicals) are added, mixed well, and have a viscosity at 25 ° C. of 2 parts. , 500 cp.

This adhesive dispersion was subjected to a release treatment of 50
A 50 μm-thick polyester film coated on a μm-thick polyester film with a comma coater and subjected to a release treatment from above is superimposed on the polyester film so as to prevent air bubbles from entering.
Irradiation with ultraviolet light having an ultraviolet intensity of 3 mW / cm ² at 65 nm was performed for 2 minutes to obtain a 50 μm thick non-substrate thermally conductive pressure-sensitive adhesive tape sheet.

The adhesive strength of the non-substrate heat conductive adhesive tape / sheet to the stainless steel plate was 4.6 N / 10 mm, and it was measured in a holding force test (load: 1 kg) at 40 ° C./24 hours or 180 ° C./1 hour. No slippage or drop was observed, showing excellent adhesiveness and heat resistance. In addition, the ball tack (angle: 30) of this heat conductive adhesive tape / sheet was used.
°) was 3 or less.

When the thermal conductivity of this non-substrate thermally conductive pressure-sensitive adhesive tape sheet was measured, it was 0.4 W / m · K, indicating thermal conductivity, while the volume resistivity was 5 × 10 ¹⁵ Ω.・ Cm
It was confirmed that the composition exhibited high insulating properties and had a sufficient function as a heat conductive adhesive tape / sheet having electrical insulating properties. Example 2 63 parts of isooctyl acrylate and 7 parts of acrylic acid were composed mainly of 2-ethylhexyl acrylate having a weight average molecular weight of 800,000 and a photoactive functional group content of 0.02 meq / g. 30 parts of an acrylic high molecular weight body,
0.05 parts of 1,6-hexanediol diacrylate,
Nickel powder # 287 (Nikko Fine Products) 50
Parts and Irgacure 819 (Ciba Specialty Chemicals) are added, mixed well, and mixed at 25 ° C.
, A uniform pressure-sensitive adhesive dispersion having a viscosity of 2,500 cp was obtained.

The pressure-sensitive adhesive dispersion was subjected to a release treatment 50
Coated with a doctor coater on a polyester film having a thickness of μm, and a polyester film having a thickness of 50 μm, which has been subjected to a peeling treatment, is stacked on the polyester film so that air bubbles do not enter.
Ultraviolet light having an intensity of 3 mW / cm ² at 365 nm was irradiated for 2 minutes to obtain a 50 μm thick non-substrate thermally conductive pressure-sensitive adhesive tape sheet.

The adhesive strength of this non-substrate heat conductive adhesive sheet to a stainless steel plate was 5.2 N / 10 mm,
In the holding force test (load: 1 kg) at ℃ / 24 hours or 180 ° C / 1 hour, no displacement or drop was observed.
It showed excellent adhesiveness and heat resistance. The pressure-sensitive adhesive sheet had a ball tack (angle: 30 °) of 3 or less.

When the thermal conductivity of this heat conductive pressure-sensitive adhesive tape / sheet was measured, it was 0.45 W / m · K, showing thermal conductivity, and the volume resistivity was 50 Ω · cm. It was confirmed that the composition had sufficient properties as a heat conductive adhesive tape sheet having conductivity. [Examples 3 to 13] In the same manner as in Examples 1 and 2,
A substrate-free heat-conductive pressure-sensitive adhesive tape / sheet was produced under the composition and production conditions shown in Table 1. In Table 1, all photopolymerization initiators used were Irgacure 819 and 0.3 parts, and 0.05 parts of 1,6-hexanediol diacrylate was added to all compositions. The light irradiation conditions are
Ultraviolet light having an ultraviolet intensity of 3 mW / cm ² was irradiated for 3 minutes.

Table 2 shows the measurement results of the adhesive strength, holding power, thermal conductivity, and volume resistivity of these non-base heat conductive adhesive tapes / sheets, all of which have excellent adhesive properties, heat resistance and heat resistance. Showed conductivity. In addition, non-base heat conductive adhesive tape
The mass productivity such as coatability, film formability and curability when producing the sheet was also good.

[0047]

[Table 1]

[0048]

[Table 2] [Comparative Example 1] Acrylic high-molecular-weight polymer 30 having a weight average molecular weight of 700,000 and 2-ethylhexyl acrylate containing no photoactive functional group as a main component in 63 parts of 2-ethylhexyl acrylate and 7 parts of acrylic acid Part, 1,6-hexanediol diacrylate 0.05 part, nickel powder # 2
87 (Nikko Fine Products) 30 parts and Irgacure 819 (Ciba Specialty Chemicals)
0.3 part was added and mixed well to obtain a uniform pressure-sensitive adhesive dispersion having a viscosity of 3,000 cp at 25 ° C.

The pressure-sensitive adhesive dispersion was subjected to a peeling treatment.
Coating on a polyester film having a thickness of μm, the ultraviolet intensity at 365 nm is 3 mW / cm ² under a nitrogen atmosphere.
For 2 minutes to obtain a 50 μm-thick non-substrate conductive pressure-sensitive adhesive tape sheet.

The adhesive strength of the adhesive tape / sheet to the stainless steel plate was 6.0 N / 10 mm, and the ball tack was 3 N.
Hereinafter, the thermal conductivity is 0.45 W / m · K, and the volume resistivity is 5
Although it was 0 Ω · cm, the holding force test at 40 ° C. (load: 1
kg), it fell in 10 minutes and was found to be inferior in holding power. [Comparative Example 2] 2-Ethylhexyl acrylate having a weight average molecular weight of 800,000 and a photoactive functional group content of 0.02 meq / g was used as a main component in 63 parts of isooctyl acrylate and 7 parts of acrylic acid. 30 parts of an acrylic high molecular weight body,
0.05 parts of 1,6-hexanediol diacrylate and 0.3 parts of Irgacure 819 (Ciba Specialty Chemicals) are sufficiently mixed to obtain a uniform adhesive dispersion having a viscosity at 25 ° C. of 3,000 cp. Was.

The pressure-sensitive adhesive solution was subjected to a release treatment to 50 μm.
A transparent 50 μm-thick polyester film coated on a m-thick polyester film and subjected to a peeling treatment is laminated thereon so as to prevent air bubbles from entering, and irradiated with ultraviolet light having an ultraviolet intensity at 365 nm of 3 mW / cm ² for 2 minutes. Then 50
A μm-thick non-base pressure-sensitive adhesive sheet was obtained.

The adhesive strength of this adhesive sheet to the stainless steel plate is 7.0 N / 10 mm, the ball tack is 3, 40 ° C.
In a holding force test (load: 1 kg) at / 24 hours or 180 ° C / 1 hour, no slippage or drop was observed, and excellent adhesiveness and heat resistance were exhibited. However, the volume resistivity is 5 ×
It was 10 ¹⁵ Ω · cm, but the thermal conductivity was 0.15 W /
m · K, which made it impossible to achieve both excellent adhesive strength, holding power and thermal conductivity.

[0053]

As described above, the present invention provides an alkyl (meth) acrylate monomer, a polar group-containing monomer, an acrylic high molecular weight material having a photoactive functional group, and a photopolymerization initiator. Non-base heat conductive adhesive tape made using a light curable heat conductive adhesive in which a good heat conductive material such as metal powder and metal oxide is dispersed in a light curable adhesive mainly composed of -In the sheet, the weight average molecular weight of the acrylic high molecular weight material having the photoactive functional group is 200,000 to 300.
Good thermal conductivity, wherein the content of the photoactive functional group is 0.001 to 0.5 meq / g, and the photocurable heat-conductive adhesive is 100 parts by weight of the photocurable adhesive. Since the content of the substance is 10 to 300 parts by weight, the adhesive strength,
It is possible to obtain a non-substrate heat-conductive pressure-sensitive adhesive tape / sheet having excellent basic adhesive properties such as high-temperature holding power and excellent heat conductivity.

Further, the present invention provides the method for producing a heat-sensitive adhesive tape / sheet without a base material, wherein the photocurable heat-conductive pressure-sensitive adhesive is applied to a thickness of 5 to 500 μm on a sheet substrate. Forming a photocurable heat conductive adhesive layer, and curing the photocurable heat conductive adhesive layer by light irradiation,
The above adhesive tape / sheet can be manufactured with good mass productivity.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kazuo Nade 3819 Notobe, Tama-ku, Kawasaki-shi, Kanagawa F-Term in Sliontec Co., Ltd. (Reference) 4J004 AA10 AA18 AB01 AB07 BA02

Claims (2)

[Claims] 1. A photo-curable pressure-sensitive adhesive comprising a (meth) acrylic acid alkyl ester monomer, a polar group-containing monomer, an acrylic polymer having a photoactive functional group and a photopolymerization initiator as main components. Non-base heat conductive adhesive tape made using a photo-curing heat conductive adhesive with a good heat conductive material dispersed in
In the sheet, the weight average molecular weight of the acrylic polymer having a photoactive functional group is from 200,000 to 3,000,000, and the content of the photoactive functional group is from 0.001 to 0.5 meq / g. And the photocurable heat-conductive pressure-sensitive adhesive contains 10 to 300 parts by weight of the good heat-conductive substance based on 100 parts by weight of the photocurable pressure-sensitive adhesive. Adhesive tape / sheet. 2. A photocurable heat-conductive pressure-sensitive adhesive according to claim 1 is applied to a thickness of 5 to 500 μm on a sheet substrate to form a photocurable heat-conductive pressure-sensitive adhesive layer. A method for producing a substrate-free heat-conductive pressure-sensitive adhesive tape / sheet, which is produced by curing the photocurable heat-conductive pressure-sensitive adhesive layer.