CN106661397B

CN106661397B - Conductive adhesive sheet

Info

Publication number: CN106661397B
Application number: CN201580045646.4A
Authority: CN
Inventors: 大高翔; 植田贵洋; 松下大雅; 松下香织; 宫田壮
Original assignee: Lintec Corp
Current assignee: Lintec Corp
Priority date: 2014-08-28
Filing date: 2015-08-24
Publication date: 2020-11-27
Anticipated expiration: 2035-08-24
Also published as: KR20170048349A; TWI678408B; JP6500904B2; CN106661397A; TW201625756A; KR102388869B1; WO2016031786A1; JPWO2016031786A1

Abstract

The invention provides a conductive adhesive sheet, which at least comprises an adhesive conductive layer (X) and a non-adhesive conductive layer (Y), wherein the adhesive conductive layer (X) is a layer formed by an adhesive composition, the adhesive composition comprises an adhesive resin (X1) and a carbon-based filler (X2) with the average length-diameter ratio of more than 1.5, the content of the carbon-based filler (X2) in the adhesive composition is 0.01-15 parts by mass relative to 100 parts by mass of the adhesive resin (X1), and the non-adhesive conductive layer (Y) is a layer comprising more than 1 conductive material selected from conductive polymers, carbon-based fillers and metal oxides. The conductive adhesive sheet has good adhesive force, and simultaneously has excellent antistatic property and conductivity.

Description

Conductive adhesive sheet

Technical Field

The present invention relates to a conductive adhesive sheet.

Background

Conventionally, conductive adhesive sheets having easy adhesiveness have been used for various joints such as electromagnetic shielding materials for containers for housing electronic devices such as computers and communication devices, grounding wires for electrical components, and materials for preventing ignition due to sparks generated by static electricity such as triboelectricity.

In order to impart antistatic properties and electrical conductivity to the pressure-sensitive adhesive composition used for the pressure-sensitive adhesive layer of the electrically conductive pressure-sensitive adhesive sheet, a composition in which an electrically conductive substance such as a metal powder, e.g., copper powder, silver powder, nickel powder, or aluminum powder, is dispersed in a pressure-sensitive adhesive resin is often used.

For example, patent document 1 discloses a conductive adhesive in which at least one of carbon nanotubes and carbon microcoils, which are conductive substances, is dispersed in a binder, and a conductive adhesive sheet using the conductive adhesive.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2001 + 172582

Disclosure of Invention

Problems to be solved by the invention

However, in order to improve the conductivity of the pressure-sensitive adhesive layer of the conductive pressure-sensitive adhesive sheet, it is necessary to mix a large amount of a conductive material in a pressure-sensitive adhesive composition as a material for forming the pressure-sensitive adhesive layer so that the particles of the conductive material are in close contact with each other.

However, when a large amount of conductive material is blended in the pressure-sensitive adhesive composition, the adhesive force of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition tends to decrease. On the other hand, if the content of the conductive material in the adhesive layer is reduced in order to improve the adhesive force, there is a problem of trade-off such that the conductivity of the adhesive layer is reduced.

The conductive pressure-sensitive adhesive sheet disclosed in patent document 1 is still insufficient in improving both the adhesive force and the conductivity.

The invention aims to provide a conductive adhesive sheet which has good adhesive force and excellent antistatic property and conductivity.

Means for solving the problems

The present inventors have found that the above problems can be solved by a conductive adhesive sheet having an adhesive conductive layer formed from an adhesive composition containing an adhesive resin and a carbon-based filler having a specific shape at a specific ratio and a non-adhesive conductive layer containing a specific conductive material, and have completed the present invention.

Namely, the present invention provides the following [1] to [14 ].

[1] A conductive adhesive sheet comprising at least an adhesive conductive layer (X) and a non-adhesive conductive layer (Y),

the adhesive conductive layer (X) is a layer formed from an adhesive composition comprising an adhesive resin (X1) and a carbon-based filler (X2) having an average aspect ratio of 1.5 or more,

the content of the carbon-based filler (x2) in the adhesive composition is 0.01 to 15 parts by mass per 100 parts by mass of the adhesive resin (x1),

the non-adhesive conductive layer (Y) is a layer containing 1 or more conductive materials selected from a conductive polymer, a carbon-based filler, and a metal oxide.

[2]Above-mentioned [1]The conductive adhesive sheet, whereinSurface resistivity (p) of the adhesive conductive layer (X)_SX) Is 1.0X 10²～1.0×10¹⁰Ω/□。

[3]Above-mentioned [1]Or [2 ]]The conductive adhesive sheet, wherein the surface resistivity (. rho.) of the non-adhesive conductive layer (Y) alone_SY) Is 1.0X 10^-2～1.0×10⁸Ω/□。

[4] The conductive adhesive sheet according to any one of the above [1] to [3], wherein the carbon-based filler (x2) contained in the adhesive composition is a carbon nanomaterial.

[5] The conductive adhesive sheet according to any one of the above [1] to [4], wherein the non-adhesive conductive layer (Y) is a layer containing 1 or more conductive materials selected from the group consisting of polythiophene, PEDOT-PSS, carbon nanomaterial, and ITO (indium tin oxide).

[6]Above-mentioned [1]～[5]The conductive adhesive sheet as claimed in any one of the above, wherein the conductive material contained in the non-adhesive conductive layer (Y) has a density of 0.8 to 2.5g/cm³。

[7] The conductive adhesive sheet according to any one of the above [1] to [6], wherein the adhesive resin (x1) contained in the adhesive composition contains 1 or more adhesive resins selected from acrylic resins, polyurethane resins, polyisobutylene resins, styrene resins, polyester resins, and polyolefin resins.

[8]Above-mentioned [1]～[7]The conductive adhesive sheet as claimed in any one of the above items, wherein the thickness (t) of the adhesive conductive layer (X)_X)1 to 1200 μm.

[9]Above-mentioned [1]～[8]The conductive adhesive sheet as claimed in any one of the above items, wherein the thickness (t) of the non-adhesive conductive layer (Y)_Y) 0.01 to 200 μm.

[10] The conductive adhesive sheet according to any one of the above [1] to [9], which has a structure in which a substrate, a non-adhesive conductive layer (Y), and an adhesive conductive layer (X) are sequentially stacked.

[11] The conductive adhesive sheet according to [10], wherein the substrate has two layers of a non-adhesive conductive layer (Y) and an adhesive conductive layer (X) on both surfaces thereof.

[12]Above-mentioned [10]Or [11]The conductive adhesive sheet, wherein the substrate has a surface resistivity of 1.0X 10¹⁴An insulating base material having a density of not less than Ω/□.

[13] The conductive adhesive sheet according to any one of [1] to [9], which has a two-layer structure comprising an adhesive conductive layer (X) and a non-adhesive conductive layer (Y) sandwiched between 2 sheets of a release sheet.

[14] The conductive adhesive sheet according to any one of the above [1] to [9], which has a three-layer structure comprising a1 st adhesive conductive layer (X-I), a non-adhesive conductive layer (Y) and a2 nd adhesive conductive layer (X-II) stacked in this order with a 2-sheet release sheet interposed therebetween.

ADVANTAGEOUS EFFECTS OF INVENTION

The conductive adhesive sheet of the present invention has good adhesive force, and is excellent in antistatic property and conductivity.

Drawings

Fig. 1 is a sectional view of a conductive adhesive sheet with a substrate, which is one of the configurations of preferred embodiments of the conductive adhesive sheet of the present invention.

Fig. 2 is a sectional view of a conductive adhesive sheet without a substrate, which is one of the configurations of the preferred embodiments of the conductive adhesive sheet of the present invention.

Description of the symbols

1A, 1B, 2A, 2B, 3,4 conductive adhesive sheet

11 adhesive conductive layer (X)

11a 1 st adhesive conductive layer (X-I)

11b adhesive conductive layer 2 (X-II)

12 non-adhesive conductive layer (Y)

12a No. 1 non-adhesive conductive layer (Y-I)

12b No. 2 non-adhesive conductive layer (Y-II)

13 base material

14 Release sheet

21 two-layer body

21a second layer 1

21b second layer of 2

22 trilayer

Detailed Description

In the present specification, "weight average molecular weight (Mw)" is a value measured by Gel Permeation Chromatography (GPC) and converted to standard polystyrene, specifically, a value measured by the method described in examples.

For example, when the term "(meth) acrylate" is used, both "acrylate" and "methacrylate" are shown, and other similar terms are also used.

In addition, unless otherwise specified, the "surface resistivity of the conductive adhesive sheet" means the surface resistivity measured from the surface side of the adhesive conductive layer (X) of the conductive adhesive sheet.

In the present invention, the values of the surface resistivity and the volume resistivity of each layer are values measured according to JIS K7194, and specifically, values measured by the methods described in examples.

[ conductive adhesive sheet ]

The conductive adhesive sheet of the present invention has at least an adhesive conductive layer (X) and a non-adhesive conductive layer (Y).

The conductive adhesive sheet of the present invention can significantly reduce the surface resistivity of the adhesive conductive layer (X) and improve antistatic properties and conductivity by providing the non-adhesive conductive layer (Y). As a result, since the adhesive conductive layer (X) does not need to contain a large amount of carbon-based filler, the conductive adhesive sheet of the present invention has good adhesive force.

In the present invention, the "adhesive conductive layer (X)" and the "non-adhesive conductive layer (Y)" are distinguished according to the presence or absence of adhesiveness, and the presence or absence of adhesiveness is determined by the peak value of probe tack (probe tack) with respect to the surface of each conductive layer.

That is, in the present invention, if the peak value of the probe adhesion force with respect to the surface of the conductive layer as the object is 0.1N or more, the conductive layer is judged to have adhesiveness and is classified as an "adhesive conductive layer (X)".

In contrast, if the peak value of the probe adhesion force with respect to the surface of the conductive layer as the object is less than 0.1N, the conductive layer is judged to be non-adhesive and classified as a "non-adhesive conductive layer (Y)".

The peak value of the probe adhesion to the surface of the conductive layer to be measured is a value measured according to JIS Z0237(1991), and specifically a value measured by the method described in the examples described later.

The conductive adhesive sheet of the present invention is not particularly limited as long as it has a structure having at least an adhesive conductive layer (X) and a non-adhesive conductive layer (Y), and may have layers other than these.

The conductive adhesive sheet according to one embodiment of the present invention may have a structure in which another layer is provided between the adhesive conductive layer (X) and the non-adhesive conductive layer (Y), but from the viewpoint of reducing the surface resistivity of the conductive adhesive sheet and improving antistatic properties and conductivity, a structure in which the adhesive conductive layer (X) and the non-adhesive conductive layer (Y) are directly laminated is preferable.

As an example of the conductive adhesive sheet according to an embodiment of the present invention, there is a conductive adhesive sheet 1A having a structure in which a substrate 13, a non-adhesive conductive layer (Y)12, and an adhesive conductive layer (X)11 are sequentially stacked as shown in fig. 1 (a). The conductive adhesive sheet 1A has a two-layer body 21 composed of a non-adhesive conductive layer (Y)12 and an adhesive conductive layer (X)11 on one surface of a substrate.

Further, a conductive adhesive sheet 1B as shown in fig. 1(B) may be formed by laminating a release sheet 14 on the adhesive conductive layer (X)11 with respect to the structure of the conductive adhesive sheet 1A.

As an example of the conductive adhesive sheet according to an embodiment of the present invention, a conductive adhesive sheet having two

layered bodies

21a and 21b each composed of a non-adhesive conductive layer (Y) and an adhesive conductive layer (X) on both surfaces of a substrate as shown in fig. 1(c) and (d) may be used.

That is, the conductive adhesive sheet 2A shown in fig. 1(c) has a1 st second layer 21a composed of a1 st non-adhesive conductive layer (Y-I)12A and a1 st adhesive conductive layer (X-I)11a on one surface of a substrate 13, and has a2 nd second layer 21b composed of a2 nd non-adhesive conductive layer (Y-II)12b and a2 nd adhesive conductive layer (X-II)11b on the other surface of the substrate 13.

The conductive adhesive sheet 2B shown in fig. 1(d) has a structure in which release sheets 14a and 14B are further laminated on the 1 st adhesive conductive layer (X-I)11a and the 2 nd adhesive conductive layer (X-II)11B, respectively, with respect to the structure of the conductive adhesive sheet 2A.

The conductive adhesive sheet according to one embodiment of the present invention may be a conductive adhesive sheet without a substrate, and specifically, a conductive adhesive sheet 3 having a structure in which a two-layer body 21 composed of an adhesive conductive layer (X)11 and a non-adhesive conductive layer (Y)12 is sandwiched between 2

peeling sheets

14a and 14b as shown in fig. 2(a) is exemplified.

As shown in fig. 2(b), the conductive adhesive sheet according to one embodiment of the present invention may be a conductive adhesive sheet 4 having a three-layer structure 22 in which a1 st adhesive conductive layer (X-I)11a, a non-adhesive conductive layer (Y)12, and a2 nd adhesive conductive layer (X-II)11b are laminated in this order with 2

peeling sheets

14a and 14b interposed therebetween.

As a conductive adhesive sheet according to an embodiment of the present invention having a structure other than the above, there can be mentioned a conductive adhesive sheet having a structure in which a material in which a two-layer body composed of an adhesive conductive layer (X) and a non-adhesive conductive layer (Y) is provided on one surface of a release sheet having both surfaces subjected to a peeling treatment so that the adhesive conductive layer (X) is exposed, is wound into a roll.

The 1 st adhesive conductive layer (X-I)11a and the 2 nd adhesive conductive layer (X-II)11b may be formed of the same adhesive composition or different adhesive compositions.

Similarly, the 1 st non-adhesive conductive layer (Y-I)12a and the 2 nd non-adhesive conductive layer (Y-II)12b may be formed of the same forming material or different forming materials.

The following description will be made of an adhesive conductive layer (X), a non-adhesive conductive layer (Y), a substrate, and a release sheet constituting the conductive adhesive sheet of the present invention.

In the present invention, the structure of the 1 st adhesive conductive layer (X-I) and the 2 nd adhesive conductive layer (X-II) is the same as the adhesive conductive layer (X), and the structure of the 1 st non-adhesive conductive layer (Y-I) and the 2 nd non-adhesive conductive layer (Y-II) is the same as the non-adhesive conductive layer (Y).

[ adhesive conductive layer (X) ]

The adhesive conductive layer (X) of the conductive adhesive sheet of the present invention is a layer formed from an adhesive composition containing an adhesive resin (X1) and a carbon-based filler (X2) having an average aspect ratio of 1.5 or more.

The adhesive conductive layer (X) has adhesiveness (the peak value of the probe adhesion is 0.1N or more) and conductivity (the volume resistivity (. rho.) of the individual layers_VX) Is 1.0X 10⁸Ω · cm or less).

Surface resistivity (. rho.) as a separate adhesive conductive layer (X)_SX) From the viewpoint of obtaining a conductive adhesive sheet having good adhesive strength and capable of effectively reducing surface resistivity, it is preferably 1.0 × 10²～1.0×10¹⁰Omega/□, more preferably 1.0X 10²～1.0×10⁸Omega/□, more preferably 1.0X 10²～1.0×10⁷Omega/□, more preferably 1.0X 10²～1.0×10⁶Ω/□。

Volume resistivity (. rho.) as a separate adhesive conductive layer (X)_VX) From the viewpoint of obtaining a conductive adhesive sheet having good adhesive strength and capable of effectively reducing surface resistivity, it is preferably 1.0 × 10⁰～1.0×10⁸Omega cm, more preferably 1.0X 10⁰～1.0×10⁶Omega cm, more preferably 1.0X 10⁰～1.0×10⁵Omega. cm, more preferably 1.0X 10⁰～1.0×10⁴Ω·cm。

Thickness (t) of adhesive conductive layer (X)_X) The particle size is suitably adjusted depending on the application, but is preferably 1 to 1200 μm, more preferably 2 to 600 μm, still more preferably 3 to 300 μm, yet more preferably 5 to 250 μm, yet more preferably 10 to 200 μm, and particularly preferably 15 to 150 μm.

Thickness (t)_X) When the thickness is 1 μm or more, a good adhesive force can be exhibited regardless of the kind of the adherend. On the other hand, thickness (t)_X) When the thickness is 1200 μm or less, the conductivity of the resulting conductive adhesive sheet becomes good. In addition, when the conductive adhesive sheet is formed into a roll, defects such as winding displacement due to deformation of the adhesive conductive layer (X) and exposure of the adhesive conductive layer (X) to the end of the roll can be suppressed.

The adhesive composition as a material for forming the adhesive conductive layer (X) includes an adhesive resin (X1) and a carbon-based filler (X2) having an average aspect ratio of 1.5 or more, but may contain a crosslinking agent, a thickening agent, and general-purpose additives other than these, depending on the type of the adhesive resin (X1).

Hereinafter, each component included in the adhesive composition will be described.

< adhesive resin (x1) >

The adhesive resin (X1) contained in the adhesive composition as a material for forming the adhesive conductive layer (X) is a resin having adhesive properties and a weight average molecular weight of 1 ten thousand or more.

The weight average molecular weight (Mw) of the adhesive resin (x1) is preferably 1 to 200 ten thousand, more preferably 2 to 150 ten thousand, from the viewpoint of improving the adhesive strength of the conductive adhesive sheet.

The content of the adhesive resin (x1) in the adhesive composition is preferably 60.0 to 99.99% by mass, more preferably 70.0 to 99.9% by mass, even more preferably 80.0 to 99.5% by mass, and even more preferably 90.0 to 99.0% by mass, based on the total amount (100% by mass) of the adhesive composition.

The adhesive resin (x1) preferably contains 1 or more adhesive resins selected from acrylic resins, polyurethane resins, polyisobutylene resins, styrene resins, polyester resins and polyolefin resins, more preferably contains 1 or more adhesive resins selected from acrylic resins, polyurethane resins, polyisobutylene resins and styrene resins, and even more preferably contains 1 or more adhesive resins selected from acrylic resins and polyurethane resins, from the viewpoint of improving the adhesive strength of the conductive adhesive sheet and improving the antistatic property and conductivity.

(acrylic resin)

As the acrylic resin that can be used as the adhesive resin (x1), for example: a polymer containing a structural unit derived from an alkyl (meth) acrylate having a linear or branched alkyl group, a polymer containing a structural unit derived from a (meth) acrylate having a cyclic structure, and the like.

The weight average molecular weight (Mw) of the acrylic resin is preferably 5 to 150 ten thousand, more preferably 15 to 130 ten thousand, even more preferably 25 to 110 ten thousand, and even more preferably 35 to 90 ten thousand.

The acrylic resin is preferably an acrylic copolymer containing a structural unit (a1) derived from an alkyl (meth) acrylate (a1 ') having an alkyl group having 1 to 20 carbon atoms (hereinafter also referred to as "monomer (a 1')"), and a structural unit (a2) derived from a functional group-containing monomer (a2 ') (hereinafter also referred to as "monomer (a 2')").

The acrylic copolymer may have a structural unit (a3) derived from a monomer (a3 ') other than the monomers (a1 ') and (a2 ').

The copolymerization mode of the acrylic copolymer is not particularly limited. That is, the acrylic copolymer may be any of a block copolymer, a random copolymer, and a graft copolymer.

The number of carbon atoms of the alkyl group of the monomer (a 1') is preferably 1 to 12, more preferably 4 to 8, and still more preferably 4 to 6, from the viewpoint of improving the adhesive properties.

Examples of the monomer (a 1') include: methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, stearyl (meth) acrylate, and the like.

Among these monomers (a 1'), butyl (meth) acrylate and 2-ethylhexyl (meth) acrylate are preferable, and butyl (meth) acrylate is more preferable.

The content of the structural unit (a1) is preferably 50 to 99.5% by mass, more preferably 60 to 99% by mass, even more preferably 70 to 97% by mass, and even more preferably 80 to 95% by mass, based on the total structural units (100% by mass) of the acrylic copolymer.

Examples of the monomer (a 2') include: hydroxyl group-containing monomers, carboxyl group-containing monomers, epoxy group-containing monomers, amino group-containing monomers, cyano group-containing monomers, ketone group-containing monomers, alkoxysilyl group-containing monomers, and the like.

Among these monomers (a 2'), carboxyl group-containing monomers are preferred.

Examples of the carboxyl group-containing monomer include: (meth) acrylic acid, maleic acid, fumaric acid, itaconic acid and the like, with (meth) acrylic acid being preferred.

The content of the structural unit (a2) is preferably 0.5 to 50% by mass, more preferably 1 to 40% by mass, even more preferably 5 to 30% by mass, and even more preferably 7 to 20% by mass, based on the total structural units (100% by mass) of the acrylic copolymer.

Examples of the monomer (a 3') include: (meth) acrylates having a cyclic structure such as cyclohexyl (meth) acrylate, benzyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, imide (meth) acrylate, and the like, vinyl acetate, acrylonitrile, styrene, and the like.

The content of the structural unit (a3) is preferably 0 to 30% by mass, more preferably 0 to 20% by mass, still more preferably 0 to 10% by mass, and still more preferably 0 to 5% by mass, based on the total structural units (100% by mass) of the acrylic copolymer.

The monomers (a1 ') to (a 3') may be used alone or in combination of 2 or more.

(polyurethane type resin)

The polyurethane resin that can be used as the adhesive resin (x1) is not particularly limited as long as it is a polymer having at least one of a urethane bond and a urea bond in the main chain and/or side chain, and examples thereof include: urethane prepolymer (α) obtained by reacting a polyol with a polyisocyanate compound, urethane polymer (β) obtained by further performing a chain extension reaction using a chain extender with respect to the urethane prepolymer (α), and the like.

Among these, the polyurethane resin used in one embodiment of the present invention preferably contains a urethane polymer having a polyoxyalkylene skeleton.

The weight average molecular weight (Mw) of the polyurethane resin is preferably 1 to 20 ten thousand, more preferably 1.2 to 15 ten thousand, still more preferably 1.5 to 10 ten thousand, and still more preferably 2 to 7 ten thousand.

Examples of the polyol to be used as a raw material of the urethane prepolymer (α) include: the polyol compound such as alkylene glycol, polyether polyol, polyester polyol, and polycarbonate polyol is not particularly limited as long as it is a polyol, and may be a 2-functional diol or a 3-functional triol.

Among these polyols, diols are preferred from the viewpoint of easiness of obtaining, reactivity, and the like.

Examples of diols include: and alkanediols such as 1, 3-propanediol, 1, 4-butanediol, 1, 5-pentanediol, neopentyl glycol, 1, 6-hexanediol, and 1, 7-heptanediol, alkylene glycols such as ethylene glycol, propylene glycol, diethylene glycol, and dipropylene glycol, polyalkylene glycols such as polyethylene glycol, polypropylene glycol, and polybutylene glycol, and polyoxyalkylene glycols such as polytetramethylene glycol. These diols may be used alone or in combination of 2 or more.

Among these diols, diols having a weight average molecular weight of 1000 to 3000 are preferable from the viewpoint of suppressing gelation during the reaction when the reaction with the chain extender is further performed.

Examples of the polyisocyanate compound to be used as a raw material of the urethane prepolymer (α) include: aromatic polyisocyanates, aliphatic polyisocyanates, alicyclic polyisocyanates, and the like.

Examples of the aromatic polyisocyanate include: 1, 3-phenylene diisocyanate, 1, 4-phenylene diisocyanate, 4 '-diphenylmethane diisocyanate (MDI), 2, 4-toluene diisocyanate (2,4-TDI), 2, 6-toluene diisocyanate (2,6-TDI), 4' -toluidine diisocyanate, 2,4, 6-triisocyanate toluene, 1,3, 5-triisocyanate benzene, anisidine diisocyanate, 4 '-diphenyl ether diisocyanate, 4' -triphenylmethane triisocyanate, 1, 4-tetramethylxylylene diisocyanate, 1, 3-tetramethylxylylene diisocyanate, and the like.

Examples of the aliphatic polyisocyanate include: trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HMDI), pentamethylene diisocyanate, 1, 2-propylene diisocyanate, 2, 3-butylene diisocyanate, 1, 3-butylene diisocyanate, dodecamethylene diisocyanate, 2,4, 4-trimethylhexamethylene diisocyanate, and the like.

Examples of the alicyclic polyisocyanate include: 3-isocyanatomethylene-3, 5, 5-trimethylcyclohexyl isocyanate (IPDI), 1, 3-cyclopentane diisocyanate, 1, 3-cyclohexane diisocyanate, 1, 4-cyclohexane diisocyanate, methyl-2, 6-cyclohexane diisocyanate, 4' -methylenebis (cyclohexyl isocyanate), 1, 4-bis (isocyanatomethyl) cyclohexane, and the like.

The polyisocyanate compound may be a modified compound (polyisocyanate) selected from the group consisting of the aromatic polyisocyanate, the aliphatic polyisocyanate, and the alicyclic polyisocyanate. Specifically, a trimethylolpropane adduct-type modified product of the compound, a biuret-type modified product obtained by reacting the compound with water, or an isocyanurate-type modified product obtained by allowing the compound to contain an isocyanurate ring may be used.

Among these polyisocyanate compounds, from the viewpoint of obtaining a urethane polymer excellent in adhesion, 1 or more selected from the group consisting of 4, 4' -diphenylmethane diisocyanate (MDI), 2, 4-tolylene diisocyanate (2,4-TDI), 2, 6-tolylene diisocyanate (2,6-TDI), hexamethylene diisocyanate (HMDI), 3-isocyanatomethylene-3, 5, 5-trimethylcyclohexyl isocyanate (IPDI) and modifications thereof are preferable, and 1 or more selected from the group consisting of HMDI, IPDI and modifications thereof is more preferable from the viewpoint of weather resistance.

The isocyanate group content (NCO%) in the urethane prepolymer (α) is preferably 0.5 to 12% by mass, more preferably 1 to 4% by mass, as measured in accordance with JIS K1603.

The chain extender is preferably a compound having 2 groups of at least one of a hydroxyl group and an amino group, or a compound having 3 or more groups of at least one of a hydroxyl group and an amino group.

The compound having 2 groups of at least one of a hydroxyl group and an amino group is preferably at least 1 compound selected from the group consisting of aliphatic diols, aliphatic diamines, alkanolamines, bisphenols, and aromatic diamines.

Examples of the aliphatic diol include: alkanediols such as 1, 3-propanediol, 1, 4-butanediol, 1, 5-pentanediol, neopentyl glycol, 1, 6-hexanediol, and 1, 7-heptanediol, and alkylene glycols such as ethylene glycol, propylene glycol, diethylene glycol, and dipropylene glycol.

Examples of the aliphatic diamine include: ethylenediamine, 1, 3-propylenediamine, 1, 4-butylenediamine, 1, 5-pentylenediamine, 1, 6-hexylenediamine, and the like.

As the alkanolamine, for example: monoethanolamine, monopropanolamine, isopropanolamine, and the like.

Examples of the bisphenol include bisphenol a.

Examples of the aromatic diamine include: diphenylmethanediamine, tolylenediamine, xylylenediamine, etc.

Examples of the compound having 3 or more groups of at least one of a hydroxyl group and an amino group include: polyhydric alcohols such as trimethylolpropane, ditrimethylolpropane, pentaerythritol and dipentaerythritol, aminoalcohols such as 1-amino-2, 3-propanediol, 1-methylamino-2, 3-propanediol and N- (2-hydroxypropylethanolamine), and ethylene oxide or propylene oxide adducts of tetramethylxylylenediamine.

(polyisobutylene resin)

The polyisobutylene-based resin (hereinafter, also referred to as "PIB-based resin") that can be used as the adhesive resin (x1) is a resin having a polyisobutylene skeleton in the main chain or in the side chain.

The weight average molecular weight (Mw) of the PIB-based resin is preferably 2 ten thousand or more from the viewpoint of sufficiently obtaining the cohesive force of the obtained adhesive composition and improving the adhesive force of the conductive adhesive sheet, and from the viewpoint of preventing contamination by an adherend, and is more preferably 3 ten thousand to 100 ten thousand, even more preferably 5 ten thousand to 80 ten thousand, and even more preferably 7 ten thousand to 60 ten thousand from the viewpoint of wettability to an adherend and solubility in a solvent.

Examples of the PIB-based resin include: polyisobutylene, a copolymer of isobutylene and isoprene, a copolymer of isobutylene and n-butene, a copolymer of isobutylene and butadiene, and halogenated butyl rubber obtained by brominating or chlorinating these copolymers, which are homopolymers of isobutylene.

When the PIB-based resin is a copolymer, the isobutylene-derived structural unit is contained in the largest amount in the entire structural units.

In the PIB resin used in one embodiment of the present invention, the content of the constitutional unit derived from isobutylene is preferably 80 to 100% by mass, more preferably 90 to 100% by mass, further preferably 95 to 100% by mass, and further preferably 98 to 100% by mass, based on the total constitutional units (100% by mass) of the PIB resin.

These PIB resins may be used alone, or 2 or more kinds may be used in combination.

Among these, from the viewpoint of improving the durability and weather resistance of the adhesive conductive layer (X) to be formed, a PIB-based resin having a dense molecular structure at the time of polymerization and containing a large amount of isobutylene-derived structural units having no polymerizable double bonds in the main chain and side chains is preferable.

In the PIB-based resin used in one embodiment of the present invention, the content of the structural unit derived from isobutylene in which no polymerizable double bond is present in the main chain and the side chain is preferably 80 to 100% by mass, more preferably 90 to 100% by mass, even more preferably 95 to 100% by mass, and even more preferably 98 to 100% by mass, based on the total structural units (100% by mass) of the PIB-based resin.

When the PIB-based resin is used, the PIB-based resin having a high weight average molecular weight and the PIB-based resin having a low weight average molecular weight are preferably used in combination.

More specifically, as the PIB-based resin used in one embodiment of the present invention, a PIB-based resin (p1) (hereinafter also referred to as "PIB-based resin (p 1)") having a weight average molecular weight of 27 to 60 ten thousand and a PIB-based resin (p2) (hereinafter also referred to as "PIB-based resin (p 2)") having a weight average molecular weight of 5 to 25 ten thousand are preferably used in combination.

The PIB-based resin (p1) having a high weight average molecular weight contributes to improvement in durability and weather resistance of the adhesive conductive layer (X) formed from the resultant adhesive composition and improvement in adhesive force.

The PIB-based resin (p2) having a low weight average molecular weight is well compatible with the PIB-based resin (p1), and can appropriately plasticize the PIB-based resin (p1), thereby contributing to improvement in wettability of the adhesive conductive layer (X) to an adherend and improvement in adhesive properties, flexibility, and the like.

From the above viewpoint, the weight average molecular weight (Mw) of the PIB-based resin (p1) is preferably 27 to 60 ten thousand, more preferably 29 to 48 ten thousand, still more preferably 31 to 45 ten thousand, and still more preferably 32 to 40 ten thousand.

From the above-described viewpoint, the weight average molecular weight (Mw) of the PIB-based resin (p2) is preferably 5 to 25 ten thousand, more preferably 8 to 23 ten thousand, even more preferably 14 to 22 ten thousand, and even more preferably 18 to 21 ten thousand.

The content ratio of the PIB resin (p2) is preferably 5 to 55 parts by mass, more preferably 6 to 40 parts by mass, still more preferably 7 to 30 parts by mass, and still more preferably 8 to 20 parts by mass, relative to 100 parts by mass of the PIB resin (p 1).

When the content of the PIB-based resin (p2) is 5 parts by mass or more, the PIB-based resin (p1) can be sufficiently plasticized, and the wettability of the formed adhesive conductive layer (X) with respect to an adherend can be improved and the adhesive strength can be improved.

On the other hand, when the content of the PIB-based resin (p2) is 55 parts by mass or less, the adhesive force, holding power, and durability of the formed adhesive conductive layer (X) can be improved.

(styrene-based resin)

The styrene-based resin that can be used as the adhesive resin (x1) is a polymer having a structural unit derived from styrene.

In the styrene-based resin used in one embodiment of the present invention, the content of the styrene-derived structural unit is preferably 5 to 50% by mass, more preferably 10 to 40% by mass, and still more preferably 15 to 35% by mass, based on the total structural units (100% by mass) of the styrene-based resin.

From the viewpoint of improving the adhesive strength of the conductive adhesive sheet, the weight average molecular weight (Mw) of the styrene-based resin is preferably 1 to 40 ten thousand, more preferably 2 to 30 ten thousand, and even more preferably 2.5 to 20 ten thousand.

The softening point of the styrene-based resin is preferably 80 to 200 ℃, more preferably 90 to 160 ℃, further preferably 100 to 140 ℃, and further preferably 105 to 135 ℃ from the viewpoint of improving the adhesive strength of the conductive adhesive sheet.

In the present invention, the softening point of the styrene-based resin is a value measured in accordance with JIS K2531.

Examples of the styrene-based resin include: styrene-butadiene-styrene triblock copolymer (hereinafter also referred to as "SBS"), styrene-block- (ethylene-co-butylene) -block-styrene triblock copolymer (hereinafter also referred to as "SEBS"), styrene-block- (ethylene-co-butylene) diblock copolymer (hereinafter also referred to as "SEB"), styrene-butadiene diblock copolymer, styrene-isoprene-styrene triblock copolymer, styrene-block- (butadiene-co-isoprene) diblock copolymer, styrene-block- (butadiene-co-isoprene) -block-styrene triblock copolymer, and the like, or carboxyl-modified products of these copolymers, and the like, And copolymers of styrene and aromatic vinyl compounds such as α -methylstyrene.

The styrene-based resins may be used alone or in combination of 2 or more.

Among these styrene-based resins, SBS, SEBS, and SEB are preferable, and SBS and SEBS are more preferable.

When the styrene-based resin is a copolymer, the copolymerization mode is not particularly limited. That is, the styrene-based resin may be any of a block copolymer, a random copolymer, and a graft copolymer.

(polyester resin)

The polyester resin that can be used as the adhesive resin (x1) is a copolymer obtained by polycondensation of an acid component and a diol component or a polyol component, and includes a modified product of the copolymer.

The polycondensation reaction can be carried out by a conventional polyesterification reaction such as a direct esterification method or an ester exchange method.

The copolymerization form of the polyester-based resin is not particularly limited. That is, the polyester-based resin may be any of a block copolymer, a random copolymer, and a graft copolymer.

Examples of the acid component include: aliphatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic anhydride, α -naphthalenedicarboxylic acid, isophthalic acid-5-sulfonic acid sodium salt, isophthalic acid-5-sulfonic acid potassium salt or esters thereof, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecylenic acid, dodecanedicarboxylic acid or esters thereof; alicyclic dicarboxylic acids such as 1, 4-cyclohexahydrophthalic anhydride, and the like.

Examples of the diol component or the polyol component include: ethylene glycol, 1, 2-propanediol, 1, 3-butanediol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, 1, 8-octanediol, 1, 9-nonanediol, neopentyl glycol, 3-methylpentanediol, 2, 3-trimethylpentanediol, aliphatic diols such as diethylene glycol, triethylene glycol and dipropylene glycol, 1, 4-cyclohexanediol, alicyclic diols such as 1, 4-cyclohexanedimethanol, and aromatic diols such as bisphenol A.

The polyester-based resin may be used alone, or 2 or more kinds thereof may be used in combination.

(polyolefin resin)

The polyolefin-based resin that can be used as the adhesive resin (x1) is a polymer having a structural unit derived from an olefin compound such as ethylene or propylene.

Examples of the polyolefin-based resin include: polyethylene such as low density polyethylene, medium density polyethylene, high density polyethylene and linear low density polyethylene, polypropylene, copolymers of ethylene and propylene, copolymers of ethylene and other α -olefins, copolymers of propylene and other α -olefins, copolymers of ethylene and other ethylenically unsaturated monomers (ethylene-vinyl acetate copolymers, ethylene-alkyl (meth) acrylate copolymers, etc.), and the like.

When the polyolefin-based resin is a copolymer, the copolymerization mode is not particularly limited. That is, the polyolefin-based resin may be any of a block copolymer, a random copolymer, and a graft copolymer.

As the above-mentioned α -olefin, for example: 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 4-methyl-1-pentene, 4-methyl-1-hexene and the like.

Examples of the ethylenically unsaturated monomer include: vinyl acetate, (meth) acrylic acid, alkyl (meth) acrylates, vinyl alcohol, and the like.

Among these polyolefin-based resins, polypropylene-based resins containing a structural unit derived from propylene, such as polypropylene, copolymers of ethylene and propylene, and copolymers of propylene and other α -olefins, are preferred.

The polyolefin resin may be used alone, or 2 or more kinds thereof may be used in combination.

< carbon-based Filler (x2) >

The adhesive composition as a material for forming the adhesive conductive layer (X) contains an adhesive resin (X1) and a carbon-based filler (X2) having an average aspect ratio of 1.5 or more.

When the average aspect ratio of the carbon-based filler (X2) is less than 1.5, the surface resistivity of the adhesive conductive layer (X) to be formed tends to increase, and even when a conductive adhesive sheet is formed by further providing a non-adhesive conductive layer (Y), it is difficult to sufficiently reduce the surface resistivity, and antistatic properties and conductivity are poor.

The average aspect ratio of the carbon-based filler (X2) is preferably 2 to 10000, more preferably 3 to 5000, further preferably 4 to 1000, further preferably 5 to 500, further more preferably 6 to 400, and particularly preferably 10 to 300, from the viewpoint of reducing the surface resistivity of the formed adhesive conductive layer (X) and improving the adhesive strength.

In the present invention, the "aspect ratio" is a value calculated from the ratio of the long side length (H) to the short side length (L) of the carbon-based filler to be treated, that is, "long side length (H)/short side length (L)". The "average aspect ratio" is an average value of the "aspect ratios" calculated for 10 carbon-based fillers.

The long side length (H) of the carbon-based filler (x2) is the length of the carbon-based filler to be used in the height direction (longitudinal direction).

On the other hand, as for the length (L) of the short side of the carbon-based filler (x2), on the cross-section orthogonal to the height direction (longitudinal direction) of the carbon-based filler to be treated, if the cross-section is a circle or an ellipse, the length (L) of the short side of the carbon-based filler (x2) means the diameter or the major axis, and if the cross-section is a polygon, the length (L) of the short side of the carbon-based filler (x2) means the diameter of the circumscribed circle of the polygon.

The length (H) of the long side of the carbon-based filler (x2) is preferably 0.01 to 2000 μm, more preferably 0.05 to 1000 μm, still more preferably 0.07 to 500 μm, and still more preferably 0.10 to 100 μm.

In the present invention, the average value of the long side lengths of the optionally selected 10 carbon-based fillers may be regarded as the value of the "long side length (H) of the carbon-based filler (x 2)".

The carbon-based filler (x2) preferably has a short side length (L) of 1 to 1000nm, more preferably 2 to 750nm, still more preferably 3 to 500nm, yet more preferably 5 to 100nm, and yet more preferably 7 to 50 nm.

In the present invention, the average value of the short side lengths of the arbitrarily selected 10 carbon-based fillers may be regarded as the value of the "short side length (L) of the carbon-based filler (x 2)".

Examples of the shape of the carbon-based filler (x2) include: columnar shape, tubular shape, spindle shape, fibrous shape, oblate spherical shape (normal sphericity is usually 0.7 or less), and a combination thereof.

Of these shapes, from the viewpoint of forming the adhesive conductive layer (X) having good conductivity, 1 or more selected from the group consisting of a columnar carbon-based filler, a cylindrical carbon-based filler, and a fibrous carbon-based filler is preferable.

The content of the carbon-based filler (x2) in the adhesive composition is 0.01 to 15 parts by mass, preferably 0.02 to 10 parts by mass, more preferably 0.30 to 7.0 parts by mass, still more preferably 0.40 to 5.0 parts by mass, still more preferably 0.50 to 4.5 parts by mass, and yet still more preferably 0.70 to 3.8 parts by mass, based on 100 parts by mass of the adhesive resin (x 1).

When the content of the carbon-based filler (X2) is less than 0.01 part by mass, the surface resistivity of the adhesive conductive layer (X) to be formed tends to be high, and even when a conductive adhesive sheet is formed by further providing a non-adhesive conductive layer (Y), it is difficult to sufficiently reduce the surface resistivity, and antistatic properties and conductivity are poor.

On the other hand, when the content of the carbon-based filler (X2) exceeds 15 parts by mass, the adhesive force of the adhesive conductive layer (X) to be formed tends to decrease.

In the conductive adhesive sheet of the present invention, since excellent antistatic properties and electrical conductivity can be exhibited even when the content of the carbon-based filler (X2) in the adhesive conductive layer (X) is small, it is not necessary to add a large amount of the carbon-based filler (X2).

From the above-mentioned viewpoint, the content of the carbon-based filler (x2) relative to the total amount (100 mass%) of the adhesive composition is usually 0.01 to 10 mass%, preferably 0.30 to 7.0 mass%, more preferably 0.40 to 5.0 mass%, still more preferably 0.50 to 4.5 mass%, and still more preferably 0.70 to 3.8 mass%.

Examples of the carbon-based filler (x2) include: carbon nanomaterials, carbon black, milled carbon fibers, graphite, and the like, but carbon nanomaterials are preferred from the viewpoint of reducing the surface resistivity of the formed adhesive conductive layer (X) and improving the adhesive force.

The carbon nanomaterial may be composed of a substance including a graphite sheet having a six-membered ring arrangement structure as a main structure, and the graphite structure may contain elements other than carbon such as boron and nitrogen, or may be in a form in which the carbon nanomaterial encapsulates another substance, or may be in a form in which the carbon nanomaterial is modified with another conductive substance.

Examples of the carbon nanomaterial include: carbon Nanotubes (CNTs), carbon nanofibers, carbon nanohorns, carbon nanocones, fullerenes, etc., with carbon nanotubes being preferred.

The carbon nanotube has a cylindrical carbon polyhedron having a cylindrical structure closed by graphite (graphite) sheets having a carbon six-membered ring structure as a main structure.

The carbon nanotube includes: any 2 or more of these may be used in combination, for example, as a single-walled carbon nanotube having a structure in which one graphite sheet is closed into a cylindrical shape, a double-walled carbon nanotube having a structure in which two graphite sheets are closed into a cylindrical shape, and a multi-walled carbon nanotube having a multi-layered structure in which graphite sheets are closed into 3 or more concentric cylindrical shapes.

< crosslinking agent >

The adhesive composition as a material for forming the adhesive conductive layer (X) may further contain a crosslinking agent.

In particular, when the acrylic resin (particularly the acrylic copolymer having the structural unit (a 2)) is used as the adhesive resin (X1), a crosslinking agent is preferably contained from the viewpoint of improving the adhesive strength of the adhesive conductive layer (X) to be formed.

Examples of the crosslinking agent include: isocyanate crosslinking agents, epoxy crosslinking agents, aziridine crosslinking agents, metal chelate crosslinking agents, amine crosslinking agents, amino resin crosslinking agents, and the like. These crosslinking agents may be used alone or in combination of 2 or more.

Among these, isocyanate-based crosslinking agents are preferable from the viewpoint of improving the adhesive strength of the conductive adhesive sheet.

Examples of the isocyanate-based crosslinking agent include: polyisocyanate compounds such as 2, 4-tolylene diisocyanate, 2, 6-tolylene diisocyanate, 1, 3-xylylene diisocyanate, 1, 4-xylylene diisocyanate, diphenylmethane-4, 4 '-diisocyanate, diphenylmethane-2, 4' -diisocyanate, 3-methyldiphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4, 4 '-diisocyanate, dicyclohexylmethane-2, 4' -diisocyanate and lysine diisocyanate.

The polyvalent isocyanate compound may be a trimethylolpropane adduct modified product of the above-mentioned compound, a biuret modified product obtained by reaction with water, or an isocyanurate modified product containing an isocyanurate ring.

The content of the crosslinking agent is preferably 0.01 to 15 parts by mass, more preferably 0.05 to 10 parts by mass, and still more preferably 0.1 to 5 parts by mass, per 100 parts by mass of the adhesive resin (x 1).

< thickening agent >

The adhesive composition as a material for forming the adhesive conductive layer (X) may further contain a thickener.

In particular, when the above-mentioned polyurethane resin, PIB resin, and styrene resin are used as the adhesive resin (X1), a thickener is preferably contained from the viewpoint of improving the adhesive strength of the adhesive conductive layer (X) to be formed.

The weight average molecular weight (Mw) of the thickener is usually less than 1 ten thousand, and is a component different from the above-mentioned adhesive resin (x 1).

The weight average molecular weight (Mw) of the thickener is preferably 400 to 4000, more preferably 800 to 1500, from the viewpoint of improving the adhesive force of the adhesive conductive layer (X) to be formed.

The softening point of the thickener is preferably 110 ℃ or higher, more preferably 110 to 180 ℃, further preferably 115 to 175 ℃, and further preferably 120 to 170 ℃.

In the present invention, the "softening point" of the thickener is a value measured in accordance with JIS K2531.

Examples of the thickener include: rosin resins such as rosin resins, rosin phenol resins, and ester compounds thereof; hydrogenated rosin resins obtained by hydrogenating these rosin resins; terpene resins such as terpene resins, aromatic modified terpene resins, and terpene phenol resins; hydrogenated terpene resins obtained by hydrogenating these terpene resins; c5-based petroleum resins obtained by copolymerizing C5 fractions such as pentene, isoprene, piperine (piperine), and 1, 3-pentadiene produced by thermal cracking of naphtha, and hydrogenated petroleum resins of the C5-based petroleum resins; a C9-based petroleum resin obtained by copolymerizing a C9 fraction such as indene, vinyl toluene, or α -or β -methylstyrene, which is produced by thermally cracking naphtha, and a hydrogenated petroleum resin of the C9-based petroleum resin; and so on.

In the present invention, the thickener may be used alone, or 2 or more kinds of thickeners having different softening points and structures may be used in combination.

The content of the thickener is preferably 1 to 200 parts by mass, more preferably 5 to 160 parts by mass, and still more preferably 10 to 120 parts by mass, per 100 parts by mass of the adhesive resin (x 1).

When the adhesive resin (x1) contains an acrylic resin, the content of the thickener is preferably 1 to 100 parts by mass, more preferably 5 to 50 parts by mass, and still more preferably 10 to 40 parts by mass, based on 100 parts by mass of the acrylic resin.

When the adhesive resin (x1) contains a polyurethane resin, the content of the thickener is preferably 5 to 200 parts by mass, more preferably 40 to 160 parts by mass, and still more preferably 80 to 120 parts by mass, based on 100 parts by mass of the polyurethane resin.

When the adhesive resin (x1) contains a PIB resin, the content of the thickener is preferably 5 to 100 parts by mass, more preferably 10 to 80 parts by mass, and still more preferably 15 to 40 parts by mass, per 100 parts by mass of the PIB resin.

When the adhesive resin (x1) contains a styrene-based resin, the content of the thickener is preferably 5 to 100 parts by mass, more preferably 15 to 80 parts by mass, and still more preferably 25 to 60 parts by mass, per 100 parts by mass of the styrene-based resin.

When the adhesive resin (x1) contains a polyester resin, the content of the thickener is preferably 5 to 100 parts by mass, more preferably 15 to 80 parts by mass, and still more preferably 25 to 60 parts by mass, per 100 parts by mass of the polyester resin.

When the adhesive resin (x1) contains a polyolefin-based resin, the content of the thickener is preferably 5 to 100 parts by mass, more preferably 15 to 80 parts by mass, and still more preferably 25 to 60 parts by mass, per 100 parts by mass of the polyolefin-based resin.

< other additives >

The adhesive composition as a material for forming the adhesive conductive layer (X) may contain a general-purpose additive commonly used with an adhesive resin, within a range not to impair the effects of the present invention.

Examples of such general-purpose additives include: ultraviolet ray absorber, antioxidant, softener (plasticizer), filler, antirust agent, pigment, dye, curing agent, curing assistant, catalyst and the like.

When these general-purpose additives are blended, the blending amount of each of the general-purpose additives is preferably 0.01 to 6 parts by mass, and more preferably 0.01 to 2 parts by mass, based on 100 parts by mass of the adhesive resin (x 1).

The total content of the adhesive resin (X1) and the carbon-based filler (X2) in the total amount (100 mass%) of the adhesive composition that is a material for forming the adhesive conductive layer (X) is preferably 20 mass% or more, and more preferably 30 mass% or more.

When the adhesive resin (x1) containing an acrylic resin as a main component is used, the total content of the adhesive resin (x1) and the carbon-based filler (x2) in the total amount (100 mass%) of the adhesive composition is preferably 60 mass% or more, more preferably 70 mass% or more, still more preferably 80 mass% or more, and still more preferably 90 mass% or more.

When the adhesive resin (x1) containing a polyurethane resin as a main component is used, the total content of the adhesive resin (x1) and the carbon-based filler (x2) in the total amount (100 mass%) of the adhesive composition is preferably 35 mass% or more, more preferably 40 mass% or more, and still more preferably 45 mass% or more, and the total content of the adhesive resin (x1), the carbon-based filler (x2), and the thickener is preferably 70 mass% or more, more preferably 80 mass% or more, and still more preferably 90 mass% or more.

When the adhesive resin (x1) containing a PIB-based resin as a main component is used, the total content of the adhesive resin (x1) and the carbon-based filler (x2) in the total amount (100 mass%) of the adhesive composition is preferably 50 mass% or more, more preferably 60 mass% or more, and still more preferably 70 mass% or more, and the total content of the adhesive resin (x1), the carbon-based filler (x2), and the thickener is preferably 70 mass% or more, more preferably 80 mass% or more, and still more preferably 90 mass% or more.

When the adhesive resin (x1) containing a styrene-based resin as a main component is used, the total content of the adhesive resin (x1) and the carbon-based filler (x2) in the total amount (100 mass%) of the adhesive composition is preferably 20 mass% or more, more preferably 25 mass% or more, and still more preferably 30 mass% or more.

The expression "adhesive resin (x1) containing ZZ-based resin as a main component" means: "the content of the ZZ-based resin is the largest among the resins contained in the adhesive resin (x 1)".

The specific content of the ZZ-based resin in this description is usually 50% by mass or more, preferably 65 to 100% by mass, more preferably 75 to 100% by mass, and further preferably 85 to 100% by mass, based on the total amount (100% by mass) of the adhesive resin (x 1).

< method for Forming adhesive conductive layer (X) >

The method for forming the adhesive conductive layer (X) is not particularly limited, and it can be produced by a known method, and examples thereof include the following methods (X-1) and (X-2).

Method (X-1): a method of preparing a solution of an organic solvent of the adhesive composition, forming a coating film by applying the solution to a release sheet described later by a known coating method, and drying the coating film to form the adhesive conductive layer (X).

Method (X-2): a method in which a composite material is prepared by heating and kneading an adhesive resin (X1), a carbon-based filler (X2), and the like, and then the composite material is molded into a sheet shape by a known molding method, thereby forming the adhesive conductive layer (X).

(method (X-1))

The method (X-1) is a preferable formation method in the case of using an acrylic resin, a polyurethane resin, a PIB resin, or the like as the adhesive resin (X1).

In the method (X-1), examples of the organic solvent to be used include: methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexane, N-hexane, toluene, xylene, N-propanol, isopropanol, dimethylformamide, N-methylpyrrolidone, dimethylsulfoxide, and the like.

These organic solvents may be used as they are in the synthesis of the adhesive resin (x 1).

In the method (X-1), the carbon-based filler (X2) is preferably blended in the binder resin (X1) in the form of a dispersion liquid dispersed in a solvent.

Since the carbon-based filler (X2) is mixed in the form of a dispersion liquid, the carbon-based filler (X2) can be easily brought close to each other and a network of the filler can be formed, and thus the surface resistivity and the volume resistivity of the adhesive conductive layer (X) to be formed can be easily reduced, since the adhesive resin (X1) can be mixed in a state of low viscosity.

Examples of the solvent used for preparing the dispersion of the carbon-based filler (x2) include water and the above-mentioned organic solvent, and an organic solvent is preferable.

Examples of the method for producing the dispersion of the carbon-based filler (x2) include: a method of adding a carbon-based filler (x2) to a solvent and applying vibration for a certain period of time by ultrasonic waves or the like.

The solid content concentration of the dispersion of the carbon-based filler (x2) is preferably 0.01 to 60 mass%, more preferably 0.05 to 10 mass%, and still more preferably 0.1 to 3 mass%.

In the method (X-1), examples of a method for applying the solution of the adhesive composition to the release sheet include: spin coating, spray coating, bar coating, knife coating, roll coating, blade coating, die coating, gravure coating, and the like.

It is preferable that a solution of the adhesive composition is applied to a release sheet to form a coating film, and then a drying treatment is performed to remove the solvent contained in the coating film.

In the method (X-1), in order to improve the adhesive strength, it is preferable that the coating layer after the drying treatment is allowed to stand in an environment of, for example, 23 ℃ and 50% RH (relative humidity) for about 7 to 30 days to sufficiently crosslink the inside of the coating layer.

(method (X-2))

The method (X-2) is a preferable formation method in the case of using a resin that can withstand heat kneading, such as a styrene-based resin, as the adhesive resin (X1).

Examples of the heating and kneading apparatus include: a single screw extruder, a twin screw extruder, a roll mill, a plastomill (plastomill), a banbury mixer, an internal mixer (intermix), a pressure kneader, and the like.

Examples of the method for molding the composite material obtained by the heating and kneading apparatus include a melt extrusion method, a rolling method, a compression molding method, and the like, and a compression molding method is preferable.

As a specific method of the compression molding method, a sheet-shaped adhesive conductive layer (X) can be molded by sandwiching the prepared composite material with 2 sheets of release sheets and heating and compressing the sheet by a hot press or the like. Instead of the 2-sheet release sheet, the prepared composite material may be sandwiched between a substrate and a release sheet to form a sheet-shaped adhesive conductive layer (X).

[ non-adhesive conductive layer (Y) ]

The non-adhesive conductive layer (Y) of the conductive adhesive sheet of the present invention is a non-adhesive layer (the peak value of the probe adhesion is less than 0.1N) and has conductivity (the volume resistivity (ρ:) of the individual layers_VX) Is 1.0X 10⁸Ω · cm or less).

Surface resistivity (. rho.) as a separate non-adhesive conductive layer (Y)_SY) From the viewpoint of obtaining a conductive adhesive sheet having effectively reduced surface resistivity, it is preferably 1.0 × 10^-2～1.0×10⁸Omega/□, more preferably 1.0X 10^-2～1.0×10⁷Omega/□, more preferably 1.0X 10^-2～1.0×10⁶Omega/□, more preferably 1.0X 10^-2～1.0×10⁵Omega/□, still more preferably 1.0X 10^-2～1.0×10⁴Omega/□, particularly preferably 1.0X 10^-2～1.0×10³Ω/□。

In one embodiment of the present invention, the surface resistivity (ρ) of the non-adhesive conductive layer (Y) alone is preferably set to effectively lower the surface resistivity of the conductive adhesive sheet_SY) Is a surface resistivity (. rho.) of the adhesive conductive layer (X) alone_SX) A small value.

Volume resistivity (. rho.) as a separate non-adhesive conductive layer (Y)_VY) From the viewpoint of obtaining a conductive adhesive sheet having effectively reduced surface resistivity, it is preferably 1.0 × 10^-4～1.0×10⁶Omega cm, more preferably 1.0X 10^-4～1.0×10⁴Omega cm, more preferably 1.0X 10^-4～1.0×10³Omega. cm, more preferably 1.0X 10^-4～1.0×10²Omega cm, still more preferably 1.0X 10^-4～1.0×10¹Omega cm, particularly preferably 1.0X 10^-4～1.0×10⁰Ω·cm。

In one embodiment of the present invention, the volume resistivity (ρ) of the non-adhesive conductive layer (Y) alone is preferably set to effectively lower the surface resistivity of the conductive adhesive sheet_VY) Is a volume resistivity (. rho.) of the adhesive conductive layer (X) alone_VX) A small value.

Thickness (t) of the non-adhesive conductive layer (Y)_Y) The particle size is preferably 0.01 to 200 μm, more preferably 0.1 to 160 μm, still more preferably 0.5 to 130 μm, and still more preferably 1.0 to 100 μm, though it can be adjusted as appropriate depending on the application.

Thickness (t)_Y) When the thickness is 0.01 μm or more, the surface resistivity of the non-adhesive conductive layer (Y) can be effectively reduced.

On the other hand, thickness (t)_Y) When the thickness is 200 μm or less, when the conductive adhesive sheet is formed into a roll, the winding displacement due to the deformation of the non-adhesive conductive layer (Y) and the defect that the non-adhesive conductive layer (Y) is exposed to the end of the roll can be suppressed. Further, by reducing the total thickness of the conductive adhesive sheet, a conductive adhesive sheet which is easily applicable to small electronic devices can be obtained.

In the present invention, the non-adhesive conductive layer (Y) is a layer containing 1 or more conductive materials selected from a conductive polymer, a carbon-based filler and a metal oxide.

Since the non-adhesive conductive layer (Y) is a layer containing these specific conductive materials, the surface resistivity of the adhesive conductive layer (X) can be significantly reduced.

From the above viewpoint, the non-adhesive conductive layer (Y) preferably contains 1 or more conductive materials selected from the group consisting of polythiophene, PEDOT-PSS, carbon nanomaterial, and ITO (indium tin oxide), and more preferably contains 1 or more conductive materials selected from the group consisting of polythiophene, PEDOT-PSS, and carbon nanomaterial.

The density of the conductive material contained in the non-adhesive conductive layer (Y) is preferably 0.8 to 2.5g/cm from the viewpoint of weight reduction of the conductive adhesive sheet³More preferably 0.8 to 2.0g/cm³More preferably 0.8 to 1.7g/cm³。

The conductive material constituting the non-adhesive conductive layer (Y) will be described below.

< conductive Polymer >

Examples of the conductive polymer include: polythiophene, PEDOT-PSS (poly (3, 4-ethylenedioxythiophene) -poly (styrenesulfonic acid)), polyaniline, polypyrrole, polyquinoxaline, and the like.

Of these, polythiophene and PEDOT-PSS are preferred.

The non-adhesive conductive layer (Y) containing a conductive polymer preferably contains a non-adhesive resin together with the conductive polymer, and the non-adhesive resin is preferably 1 or more non-adhesive resins selected from acrylic resins, polyurethane resins, PIB resins, and styrene resins.

When a conductive polymer is used as the conductive material, the content of the conductive polymer is preferably 4 to 100% by mass, more preferably 8 to 100% by mass, based on the total amount (100% by mass) of the non-adhesive conductive layer (Y).

The method for forming the non-adhesive conductive layer (Y) comprising a conductive polymer is not particularly limited, and examples thereof include the following methods: a solution containing an organic solvent for the conductive polymer is prepared, and the solution is applied to a substrate or a release sheet by a known coating method to form a coating film, and the coating film is dried to form the non-adhesive conductive layer (Y) containing the conductive polymer.

The kind of the organic solvent and the method of applying the solution used in this method are the same as those described in the above "method (X-1)" as the method of forming the adhesive conductive layer (X).

< carbon-based Filler >

Examples of the carbon-based filler include the same materials as those of the carbon-based filler (x2), and a carbon nanomaterial is preferable.

The non-adhesive conductive layer (Y) containing a carbon-based filler preferably contains a non-adhesive resin together with the carbon-based filler, and the non-adhesive resin is preferably 1 or more non-adhesive resins selected from acrylic resins, polyurethane resins, PIB resins, and styrene resins.

When a carbon-based filler is used as the conductive material, the content of the carbon-based filler is preferably 0.1 to 20% by mass, more preferably 0.5 to 15% by mass, even more preferably 1.0 to 10% by mass, and even more preferably 2.0 to 7% by mass, based on the total amount (100% by mass) of the non-adhesive conductive layer (Y).

The method for forming the non-adhesive conductive layer (Y) containing a carbon-based filler is not particularly limited, and examples thereof include the following methods: the solution of the resin composition is prepared by mixing a dispersion liquid of the carbon-based filler and a solution of the non-adhesive resin in an organic solvent, and then the solution is coated on a substrate or a release sheet by a known coating method to form a coating film, and the coating film is dried to form the non-adhesive conductive layer (Y) containing the carbon-based filler.

The kind of organic solvent used in this method, the method for preparing a dispersion of a carbon-based filler, and the method for applying a solution are the same as those described above in "method (X-1)" as a method for forming the adhesive conductive layer (X).

In addition, as a method for forming the non-adhesive conductive layer (Y) containing a carbon-based filler, a method may be used in which a composite material is prepared by heating and kneading a carbon-based filler and a non-adhesive resin, and then the composite material is formed into a sheet by a known molding method to obtain the non-adhesive conductive layer (Y) containing a carbon-based filler.

The heating kneader and the method for molding the composite material used in this method are the same as those described above in "method (X-2)" as a method for forming the adhesive conductive layer (X).

< Metal oxide >

As the metal oxide, there can be mentioned: ITO (indium tin oxide), ZnO (zinc oxide), IZO (indium zinc oxide), AZO (aluminum zinc oxide), GZO (gallium zinc oxide), IGZO (indium gallium zinc oxide), ATO (antimony tin oxide), and the like.

Among these, ITO (indium tin oxide) is preferable.

In the case of using a metal oxide as the conductive material, the non-adhesive conductive layer (Y) is preferably a layer formed only of the metal oxide.

As a method for forming the non-adhesive conductive layer (Y) containing a metal oxide, a method of forming the non-adhesive conductive layer (Y) on a substrate by vapor deposition is preferable.

[ base Material ]

The substrate used for the conductive adhesive sheet in one embodiment of the present invention may be appropriately selected depending on the use of the conductive adhesive sheet, and may be an insulating substrate containing an insulating material or a conductive substrate containing a conductive material such as a metal.

In the present invention, the insulating base material has a surface resistivity of 1.0X 10¹⁴Omega/□ or more (preferably 1.0X 10)¹⁶Omega/□ or higher).

Examples of the insulating base material include: various papers such as full size paper, art paper, coated paper, cellophane paper, and laminated paper obtained by laminating thermoplastic resins such as polyethylene on these paper substrates; porous materials such as nonwoven fabrics; plastic films or sheets made of polyolefin resins such as polyethylene resins and polypropylene resins, polyester resins such as polybutylene terephthalate resins and polyethylene terephthalate resins, acetate resins, ABS resins, polystyrene resins, vinyl chloride resins, and the like; a plastic film or sheet formed of a mixture of these resins; plastic films or sheets formed of a laminate of these plastic films or sheets, and the like.

The base material such as a plastic film or sheet may be unstretched, or may be stretched in a uniaxial direction or a biaxial direction such as a longitudinal direction or a transverse direction.

These insulating substrates (particularly plastic films or sheets) may further contain ultraviolet absorbers, light stabilizers, antioxidants, antistatic agents, slip agents, antiblocking agents, colorants, and the like.

Examples of the conductive substrate include: a metal foil, a film or sheet obtained by laminating a metal foil with a resin or the like that forms the insulating base material, a film or sheet obtained by performing a metal vapor deposition treatment on the surface of the insulating base material, a film or sheet obtained by performing an antistatic treatment on the surface of the insulating base material, a sheet obtained by weaving metal wires in a mesh shape, and the like.

As the metal used for the conductive base material, for example, there can be mentioned: aluminum, copper, silver, gold, and the like.

The thickness of the base material is not particularly limited, but is preferably 10 to 250 μm, more preferably 15 to 200 μm, and still more preferably 20 to 150 μm, from the viewpoint of ease of handling.

When the substrate is a plastic film or sheet, it is preferable to subject the surface of the substrate to a surface treatment such as an oxidation method or an embossing method as necessary, from the viewpoint of improving the adhesion between the substrate and the non-adhesive conductive layer (Y).

The oxidation method is not particularly limited, and examples thereof include: corona discharge treatment, plasma treatment, chromic acid oxidation (wet), flame treatment, hot air treatment, ozone/ultraviolet irradiation treatment, and the like. The method of forming the concavities and convexities is not particularly limited, and examples thereof include: sand blasting, solvent treatment, and the like. These surface treatments may be appropriately selected depending on the type of the substrate, but from the viewpoint of the effect of improving the adhesion to the non-adhesive conductive layer (Y) and the workability, a corona discharge treatment method is preferable. In addition, plasma treatment may be performed.

[ Release sheet ]

In addition, as the release sheet used for the conductive adhesive sheet in one embodiment of the present invention, a release sheet subjected to a double-sided release treatment, a release sheet subjected to a single-sided release treatment, or the like can be used, and examples thereof include a release sheet obtained by applying a release agent to a release sheet substrate.

Examples of the base material for a release sheet include: paper substrates such as cellophane, coated paper and fully-pulped paper, laminated paper obtained by laminating thermoplastic resins such as polyethylene on these paper substrates, plastic films such as polyester resin films such as polyethylene terephthalate resin, polybutylene terephthalate resin and polyethylene naphthalate resin, and polyolefin resin films such as polypropylene resin and polyethylene resin.

Examples of the release agent include: rubber elastomers such as silicone resins, olefin resins, isoprene resins, and butadiene resins, long-chain alkyl resins, alkyd resins, and fluorine resins.

The thickness of the release sheet is not particularly limited, but is preferably 10 to 200 μm, more preferably 25 to 150 μm.

[ method for producing conductive adhesive sheet, physical Properties ]

The conductive adhesive sheet according to one embodiment of the present invention can be produced by appropriately bonding the adhesive conductive layer (X) and the non-adhesive conductive layer (Y) formed by the above-described forming method, and the substrate and the release sheet.

The peak value of the probe adhesion to the surface of the adhesive conductive layer (X) of the conductive adhesive sheet according to one embodiment of the present invention is preferably 0.1N or more, more preferably 0.1 to 49N, even more preferably 0.5 to 49N, and even more preferably 1.0 to 49N.

The peak value of the probe adhesion force represents a value measured by the method described in examples. The peak value of the probe adhesion is a physical property value as an index of the adhesive force of the conductive adhesive sheet, and the larger the value, the higher the adhesive force.

The surface resistivity (ρ) measured from the surface side of the adhesive conductive layer (X) of the conductive adhesive sheet according to one embodiment of the present invention_S) Preferably 9.0X 10⁴Omega/□ or less, more preferably 1.0X 10⁴Omega/□ or less, more preferably 5.0X 10³Omega/□ or less, more preferably 2.0X 10³Omega/□ or less.

The value of "surface resistivity measured from the surface side of the adhesive conductive layer (X) of the conductive adhesive sheet" is determined from at least the adhesive conductive layer (X) and the non-adhesive conductive layerThe value of the surface resistivity measured on the surface side of the exposed adhesive conductive layer (X) of the conductive adhesive sheet of the present invention in which the adhesive conductive layer (Y) is laminated is different from the surface resistivity (ρ) of the aforementioned "adhesive conductive layer (X) alone_SX) "is used.

Examples

The physical properties of the components used in the following examples and comparative examples, and the physical properties of the conductive adhesive sheet, the adhesive conductive layer (X), and the non-adhesive conductive layer were measured by the methods described below.

< weight average molecular weight (Mw) >

The measurement was carried out under the following conditions using a gel permeation chromatography apparatus (product name "HLC-8020" manufactured by Tosoh corporation) and the value was converted to standard polystyrene.

(measurement conditions)

Column chromatography: a column was prepared by connecting "TSK guard column HXL-H", "TSK gel GMHXL (. times.2)" and "TSK gel G2000 HXL" (all available from Tosoh Corp.) in this order.

Column temperature: 40 deg.C

Elution solvent: tetrahydrofuran (THF)

Flow rate: 1.0mL/min

< length-to-diameter ratio, length of long side and length of short side of carbon-based filler >

The randomly selected 10-carbon filler particles were observed with a scanning electron microscope (product name "S-4700" manufactured by Hitachi High-Technologies, ltd.), the length of each long side and the length of each short side were measured, and the average value of the 10-carbon filler particles was defined as the "length of the long side (H)" and the "length of the short side (L)" of the filler. The aspect ratio (H/L) is calculated by "long side length (H)/short side length (L)".

< softening Point >

Measured according to JIS K2531.

< Density >

The measurement was carried out according to JIS Z8807: 2012.

< Probe adhesion >

The assay was performed based on J IS Z0237 (1991).

Specifically, a test piece having a size of 10mm × 10mm was allowed to stand at 23 ℃ in an environment of 50% RH (relative humidity) for 24 hours, and then the surface of the layer to be measured was exposed, and the PROBE adhesion value to the surface of the layer was measured by an adhesion tester (product name "PROBE TACK TESTER" manufactured by physical and industrial co., ltd.).

It should be noted that the probe adhesion values are as follows: a probe made of stainless steel having a diameter of 5mm was set at 0.98N/cm²After the contact load of (2) was brought into contact with the surface of the layer to be measured for 1 second, the probe was moved away from the surface at a speed of 600 mm/sec, and the force required at that time was taken as the probe adhesion value of the surface of the layer.

In addition, the peak value of the probe adhesion value was measured with respect to the surface of the non-adhesive conductive layer. The peak value and the integrated value of the probe adhesion value were measured with respect to the surface of the adhesive conductive layer (X) of the conductive adhesive sheet.

When the surface of the layer to be measured has no adhesiveness and the peak of the probe adhesion value cannot be measured, the peak is set to "0 (N)".

< surface resistivity, volume resistivity >

The measurement was carried out according to JIS K7194.

Specifically, a test piece having a size of 20mm × 40mm was allowed to stand at 23 ℃ in an environment of 50% RH (relative humidity) for 24 hours, and then the surface of the layer to be measured of the test piece was exposed, and the surface resistivity and the volume resistivity were measured by a low resistivity meter (product name "Loresta GP MCP-T610" manufactured by Mitsubishi Chemical Analytech).

The above measurements were performed 3 times for surface resistivity and 5 times for volume resistivity, and the average values of the measurement values obtained in the respective measurements are shown in tables 1 and 2.

In the measurement of the surface resistivity and the volume resistivity of the adhesive conductive layer (X) alone, a laminate in which only the adhesive conductive layer (X) was sandwiched between 2 sheets of release sheets was used as a test piece, and one side of the release sheet of the test piece was removed, and these values were measured with respect to the surface of the exposed adhesive conductive layer (X).

In the measurement of the surface resistivity and the volume resistivity of the non-adhesive conductive layer alone, a substrate with a non-adhesive conductive layer was used as a test piece, and the values were measured with respect to the surface of the non-adhesive conductive layer of the test piece.

Further, in the measurement of the surface resistivity of the conductive adhesive sheet, the conductive adhesive sheet prepared in examples and comparative examples, in which the substrate, the non-adhesive conductive layer, the adhesive conductive layer (X), and the release sheet were sequentially laminated, was used as a test piece, the release sheet of the test piece was removed, and only the value of the surface resistivity was measured with respect to the exposed surface of the adhesive conductive layer (X).

Production example 1

(preparation of substrate with non-adhesive conductive layer (Y-1))

A polyethylene terephthalate (PET) film (product name "LUMIRROR" manufactured by Toray corporation) having a thickness of 50 μm and having a surface resistivity of 1.18X 10 was used as a substrate¹⁸Omega/□) was coated with a solution of polythiophene (product of Soken chemical Co., Ltd., trade name "Berazol IW-103") so that the thickness after drying became 2.4 μm to form a coating film, and the coating film was dried to obtain a substrate with a non-adhesive conductive layer (Y-1) containing polythiophene.

Production example 2

(preparation of substrate with non-adhesive conductive layer (Y-2))

A solution containing 10 parts by mass (solid content ratio) of a dispersion (product name "Orgacon S305" manufactured by Agfa) of poly (3, 4-ethylenedioxythiophene) -poly (styrenesulfonic acid) (PEDOT-PSS) and 10 parts by mass of ethylene glycol per 100 parts by mass (solid content) of an acrylic water-soluble polymer (product name "tamanio G-37" manufactured by seikagawa chemical industries, ltd.) was prepared.

Then, the solution was applied to the same PET film as used in production example 1 so that the dried thickness became 1.0. mu.m, to form a coating film, and the coating film was dried, to obtain a substrate with a non-adhesive conductive layer (Y-2) comprising PEDOT-PSS.

Production example 3

(preparation of substrate with non-adhesive conductive layer (Y-3))

A composite material was obtained by adding 10 parts by mass (solid content ratio) of multi-walled Carbon Nanotubes (CNTs) (trade name "NC 7000" manufactured by Nanoshiru, described in detail later) to 100 parts by mass (solid content) of a styrene-based resin (product name "1726M" manufactured by Clayton corporation, SEBS), and kneading the mixture at 100 ℃ and 50rpm using a heated kneader (product name "30C 150" manufactured by tokyo seiki corporation).

Then, the composite material was sandwiched by the same PET film as used in production example 1 and a release sheet (product name "SP-PET 751031" manufactured by Lindeke corporation) having a thickness of 75 μm, and hot-pressed at 130 ℃ and 10MPa for 10 minutes by using a hot press (product name "SA-302" manufactured by Tester Sangyo Co., Ltd.). After hot pressing, the release sheet was removed to obtain a substrate with a non-adhesive conductive layer (Y-3) comprising SEBS and CNT (10 parts by mass) and having a thickness of 100.0. mu.m.

In the present example and comparative example, the following substrates with a non-adhesive conductive layer were used in addition to the substrates with a non-adhesive conductive layer produced in production examples 1 to 3.

"substrate with non-adhesive conductive layer (Y-a) comprising ITO": the trade name is "ITO-POLYETHYLENE TEREPHTHALATE" (manufactured by Nissui Kogyo Co., Ltd.). In a 50 μm thick PET film (surface resistivity: 1.18X 10)¹⁸Omega/□) was vapor-deposited with an ITO film having a thickness of 1.6 μm on one surface thereof.

"substrate with non-adhesive conductive layer (Y-B) comprising copper": the product name is "NIKAFLEX" (manufactured by Nikkan Industries Co., Ltd.). In a 50 μm thick PET film (surface resistivity: 1.18X 10)¹⁸Omega/□) was bonded to one surface of the substrate with a copper film having a thickness of 35.0 μm using an adhesive.

Substrates with non-adhesive conductive layers (Y-C) comprising aluminum: trade name "Metarumi #50 "('TORAY' Innovation by Chemistry, Inc.). In a 50 μm thick PET film (surface resistivity: 1.18X 10)¹⁸Omega/□) was vapor-deposited with an aluminum film having a thickness of 10.0 μm on one surface thereof.

The properties of the non-adhesive conductive layer of the substrate with a non-adhesive conductive layer used in the examples and comparative examples are shown in table 1.

TABLE 1

Examples 1 to 15 and comparative examples 1 to 8

(1) Formation of adhesive conductive layer (X)

A dispersion of the carbon-based filler (x2) having a solid content concentration of 0.5 mass% was prepared in advance by adding the carbon-based filler (x2) of the kind and amount (solid content ratio with respect to 100 parts by mass (solid content)) shown in table 2 to ethyl acetate and applying vibration by ultrasonic waves (42kHz, 125W) for 1 hour by an ultrasonic cleaner.

Next, the dispersion of the carbon-based filler (x2) was added to 100 parts by mass (solid content) of the adhesive resin (x1) of the type shown in table 2, and if necessary, a crosslinking agent and a thickening agent of the type and amount (solid content ratio) shown in table 2 were added. Then, a solution of the adhesive composition was prepared by appropriately diluting with ethyl acetate and stirring until uniformity was achieved.

Then, the solution of the adhesive composition prepared as described above was applied to a release-treated surface of a release sheet (product of Lindcokeko K.K., trade name "SP-PET 381031", thickness: 38 μm, surface of which was a polyethylene terephthalate film subjected to a silicone release treatment) to form a coating film, and the coating film was dried to form a coating layer.

Next, a release sheet of the same kind as described above was additionally laminated on the coating layer, and after standing for 14 hours in an atmosphere of 23 ℃ and 50% RH (relative humidity), the coating layer was sufficiently crosslinked, to obtain a laminate in which only the adhesive conductive layer (X) having a thickness shown in table 2 was sandwiched between 2 release sheets.

(2) Production of conductive adhesive sheet

In examples 1 to 15 and comparative examples 7 to 8, conductive adhesive sheets were produced by bonding the adhesive conductive layer (X) exposed by removing one side of the release sheet of the laminate to the non-adhesive conductive layer of the substrate with a non-adhesive conductive layer of the type shown in table 2.

In comparative examples 1 to 6, an adhesive conductive layer (X) exposed by removing one side of the release sheet of the laminate was bonded to a PET film (product name "LUMIRROR" of Toray corporation) having a thickness of 50 μm to prepare a conductive adhesive sheet.

Example 16

(1) Formation of adhesive conductive layer (X)

Multiwall Carbon Nanotubes (CNTs) (trade name "NC 7000" manufactured by Nanoshiru, Inc., and detail shown below) were added to 100 parts by mass (solid content) of a styrene-based resin (trade name "P-907Y" manufactured by TOYO ADL K.K., and detail shown below) in the blending amounts (solid content ratios) shown in Table 2, and the mixture was kneaded at 100 ℃ and 50rpm using a heated kneader (trade name "30C 150" manufactured by Toyo Seiki K.K.).

Then, the composite material was sandwiched by 2 release sheets (product name "SP-PET 751031" manufactured by Lindeke corporation, thickness: 75 μm), and hot-pressed by a hot press (product name "SA-302" manufactured by Tester Sangyo Co., Ltd.) at 130 ℃ and 10MPa for 10 minutes to obtain a laminate in which only the adhesive conductive layer (X) was sandwiched by the 2 release sheets.

(2) Production of conductive adhesive sheet

An adhesive conductive layer (X) comprising a styrene resin exposed by removing one side of the release sheet of the laminate was bonded to a non-adhesive conductive layer of a substrate having a non-adhesive conductive layer (Y-2), to prepare a conductive adhesive sheet.

The details of each component of the adhesive compositions used in examples and comparative examples shown in table 2 are as follows.

(adhesive resin (x1))

"acrylic resin": methyl acetate solution of an acrylic polymer formed from n-Butyl Acrylate (BA) and Acrylic Acid (AA), BA/AA of 90.0/10.0 (parts by mass), Mw: 70 ten thousand, solid content concentration: 33.6% by mass.

"polyurethane resin": the product name "U.S. Pat. No. 902A" manufactured by Lion Specialty Chemicals, polyurethane resin, Mw 56,000.

"PIB-based resin": 90.9 parts by mass (solid content ratio) of a PIB resin having an Mw of 34 ten thousand (product name "Oppanol B50" manufactured by BASF corporation) and 9.1 parts by mass (solid content ratio) of a PIB resin having an Mw of 20 ten thousand (product name "Oppanol B30" manufactured by BASF corporation).

Styrene resin ": trade name "P-907Y" manufactured by TOYO ADL corporation, a mixed resin containing SEBS and SEB, a total content of SEBS and SEB being 30 mass%, and a softening point being 112 ℃.

(carbon-based Filler (x2))

"NC 7000": trade name, cylindrical multi-walled carbon nanotube manufactured by Nanoshiru, average aspect ratio (H/L): 150. length of long side (H): 1.5 μm, short side length (L): 10 nm.

"AMC": trade name, cylindrical multi-walled carbon nanotube manufactured by Utsu Kyoho, average aspect ratio (H/L): 100. length of long side (H): 1.1 μm, short side length (L): 11 nm.

(crosslinking agent)

"CORONATE L": trade name, manufactured by Tosoh corporation, isocyanate-based crosslinking agent, solid content concentration: 75% by mass.

(thickening agent)

"Alcon P-125": trade name, manufactured by seikagawa chemical industries co., ltd., hydrogenated petroleum resin, softening point: 125 ℃.

"YS Polystar K125": trade name, manufactured by Yasuhara Chemical co., ltd., terpene phenol resin, softening point: 125 ℃.

(other Components)

A mixture of components (such as a thickener and a plasticizer) other than the component (x1) contained in "P-907Y" used as a styrene-based resin.

Table 2 shows various physical property values measured by the above method for the conductive adhesive sheet produced as described above.

As is clear from table 2, the conductive adhesive sheets of examples 1 to 16 have good adhesive force, and have lower surface resistivity, and excellent antistatic property and conductivity as compared with the conductive adhesive sheets of comparative examples 1 to 8.

Industrial applicability

The conductive adhesive sheet of the present invention has excellent adhesion and low surface resistivity, and therefore, is excellent in antistatic properties and conductivity.

Therefore, the conductive adhesive sheet of the present invention is suitable as a joining member for electromagnetic shielding materials of containers for housing electronic devices such as computers and communication devices, grounding wires of electrical components and the like, and members such as ignition-preventing materials for preventing ignition due to sparks generated by static electricity such as triboelectricity and the like.

Claims

1. A conductive adhesive sheet comprising at least an adhesive conductive layer (X) and a non-adhesive conductive layer (Y),

the conductive adhesive sheet has a structure in which a substrate, a non-adhesive conductive layer (Y), and an adhesive conductive layer (X) are sequentially laminated,

2. The conductive adhesive sheet according to claim 1, wherein the surface resistivity (ρ) of the adhesive conductive layer (X) alone is_SX) Is 1.0X 10²～1.0×10¹⁰Ω/□。

3. The conductive adhesive sheet according to claim 1, wherein the surface resistivity (ρ) of the individual non-adhesive conductive layer (Y)_SY) Is 1.0X 10^-2～1.0×10⁸Ω/□。

4. The conductive adhesive sheet according to claim 2, wherein the surface resistivity (ρ) of the individual non-adhesive conductive layer (Y)_SY) Is 1.0X 10^-2～1.0×10⁸Ω/□。

5. The conductive adhesive sheet according to claim 1, wherein the carbon-based filler (x2) contained in the adhesive composition is a carbon nanomaterial.

6. The conductive adhesive sheet according to claim 2, wherein the carbon-based filler (x2) contained in the adhesive composition is a carbon nanomaterial.

7. The conductive adhesive sheet according to claim 3, wherein the carbon-based filler (x2) contained in the adhesive composition is a carbon nanomaterial.

8. The conductive adhesive sheet according to claim 4, wherein the carbon-based filler (x2) contained in the adhesive composition is a carbon nanomaterial.

9. The conductive adhesive sheet according to any one of claims 1 to 8, wherein the non-adhesive conductive layer (Y) is a layer containing 1 or more conductive materials selected from the group consisting of polythiophene, PEDOT-PSS, carbon nanomaterial, and ITO (indium tin oxide).

10. The conductive adhesive sheet according to any one of claims 1 to 8, wherein the conductive material contained in the non-adhesive conductive layer (Y) has a density of 0.8 to 2.5g/cm³。

11. The conductive adhesive sheet according to claim 9, wherein the density of the conductive material contained in the non-adhesive conductive layer (Y) is 0.8 to 2.5g/cm³。

12. The conductive adhesive sheet according to any one of claims 1 to 8, wherein the adhesive resin (x1) contained in the adhesive composition contains 1 or more adhesive resins selected from acrylic resins, polyurethane resins, polyisobutylene resins, styrene resins, polyester resins, and polyolefin resins.

13. The conductive adhesive sheet according to claim 9, wherein the adhesive resin (x1) contained in the adhesive composition contains 1 or more adhesive resins selected from acrylic resins, polyurethane resins, polyisobutylene resins, styrene resins, polyester resins, and polyolefin resins.

14. The conductive adhesive sheet according to claim 10, wherein the adhesive resin (x1) contained in the adhesive composition contains 1 or more adhesive resins selected from acrylic resins, polyurethane resins, polyisobutylene resins, styrene resins, polyester resins, and polyolefin resins.

15. The conductive adhesive sheet according to any one of claims 1 to 8, wherein the thickness (t) of the adhesive conductive layer (X)_X)1 to 1200 μm.

16. The conductive adhesive sheet according to claim 9, wherein the thickness (t) of the adhesive conductive layer (X)_X)1 to 1200 μm.

17. The conductive adhesive sheet according to claim 10, wherein the thickness (t) of the adhesive conductive layer (X)_X)1 to 1200 μm.

18. The conductive adhesive sheet according to claim 12, wherein the thickness (t) of the adhesive conductive layer (X)_X)1 to 1200 μm.

19. The conductive adhesive sheet according to any one of claims 1 to 8, wherein the thickness (t) of the non-adhesive conductive layer (Y)_Y) 0.01 to 200 μm.

20. The conductive adhesive sheet according to claim 9, wherein the thickness (t) of the non-adhesive conductive layer (Y)_Y) 0.01 to 200 μm.

21. The conductive adhesive sheet according to claim 10, wherein the thickness (t) of the non-adhesive conductive layer (Y)_Y) 0.01 to 200 μm.

22. The conductive adhesive sheet according to claim 12, wherein the thickness (t) of the non-adhesive conductive layer (Y)_Y) 0.01 to 200 μm.

23. The conductive adhesive sheet according to claim 15, wherein the thickness (t) of the non-adhesive conductive layer (Y)_Y) 0.01 to 200 μm.

24. The conductive adhesive sheet according to claim 1, wherein a two-layer body comprising the non-adhesive conductive layer (Y) and the adhesive conductive layer (X) is provided on each of both surfaces of the substrate.

25. The conductive adhesive sheet according to claim 1, wherein the substrate has a surface resistivity of 1.0 x 10¹⁴An insulating base material having a density of not less than Ω/□.

26. The method of claim 24The conductive adhesive sheet of (1), wherein the substrate has a surface resistivity of 1.0X 10¹⁴An insulating base material having a density of not less than Ω/□.

27. The conductive adhesive sheet according to any one of claims 1 to 8, which has a structure in which a two-layer body comprising the adhesive conductive layer (X) and the non-adhesive conductive layer (Y) is sandwiched between 2 sheets of release sheets.

28. The conductive adhesive sheet according to claim 9, which has a two-layer structure comprising an adhesive conductive layer (X) and a non-adhesive conductive layer (Y) sandwiched between 2 sheets of release sheets.

29. The conductive adhesive sheet according to claim 10, which has a two-layer structure comprising an adhesive conductive layer (X) and a non-adhesive conductive layer (Y) sandwiched between 2 sheets of release sheets.

30. The conductive adhesive sheet according to claim 12, which has a two-layer structure comprising an adhesive conductive layer (X) and a non-adhesive conductive layer (Y) sandwiched between 2 sheets of release sheets.

31. The conductive adhesive sheet according to claim 15, which has a two-layer structure comprising an adhesive conductive layer (X) and a non-adhesive conductive layer (Y) sandwiched between 2 sheets of release sheets.

32. The conductive adhesive sheet according to claim 19, which has a two-layer structure comprising the adhesive conductive layer (X) and the non-adhesive conductive layer (Y) sandwiched between 2 sheets of release sheets.

33. The conductive adhesive sheet according to claim 24, which has a two-layer structure comprising the adhesive conductive layer (X) and the non-adhesive conductive layer (Y) sandwiched between 2 sheets of release sheets.

34. The conductive adhesive sheet according to claim 25, which has a two-layer structure comprising the adhesive conductive layer (X) and the non-adhesive conductive layer (Y) sandwiched between 2 sheets of release sheets.

35. The conductive adhesive sheet according to any one of claims 1 to 8, which has a three-layer structure comprising a1 st adhesive conductive layer (X-I), a non-adhesive conductive layer (Y) and a2 nd adhesive conductive layer (X-II) stacked in this order with a 2-sheet release sheet sandwiched therebetween.

36. The conductive adhesive sheet according to claim 9, which has a three-layer structure comprising a1 st adhesive conductive layer (X-I), a non-adhesive conductive layer (Y) and a2 nd adhesive conductive layer (X-II) stacked in this order with a 2-sheet release sheet sandwiched therebetween.

37. The conductive adhesive sheet according to claim 10, which has a three-layer structure comprising a1 st adhesive conductive layer (X-I), a non-adhesive conductive layer (Y) and a2 nd adhesive conductive layer (X-II) stacked in this order with a 2-sheet release sheet sandwiched therebetween.

38. The conductive adhesive sheet according to claim 12, which has a three-layer structure comprising a1 st adhesive conductive layer (X-I), a non-adhesive conductive layer (Y) and a2 nd adhesive conductive layer (X-II) stacked in this order with a 2-sheet release sheet sandwiched therebetween.

39. The conductive adhesive sheet according to claim 15, which has a three-layer structure comprising a1 st adhesive conductive layer (X-I), a non-adhesive conductive layer (Y) and a2 nd adhesive conductive layer (X-II) stacked in this order with a 2-sheet release sheet sandwiched therebetween.

40. The conductive adhesive sheet according to claim 19, which has a three-layer structure comprising a1 st adhesive conductive layer (X-I), a non-adhesive conductive layer (Y) and a2 nd adhesive conductive layer (X-II) stacked in this order with a 2-sheet release sheet sandwiched therebetween.

41. The conductive adhesive sheet according to claim 24, which has a three-layer structure comprising a1 st adhesive conductive layer (X-I), a non-adhesive conductive layer (Y) and a2 nd adhesive conductive layer (X-II) stacked in this order with a 2-sheet release sheet sandwiched therebetween.

42. The conductive adhesive sheet according to claim 25, which has a three-layer structure comprising a1 st adhesive conductive layer (X-I), a non-adhesive conductive layer (Y) and a2 nd adhesive conductive layer (X-II) stacked in this order with a 2-sheet release sheet interposed therebetween.

43. The conductive adhesive sheet according to claim 27, which has a three-layer structure comprising a1 st adhesive conductive layer (X-I), a non-adhesive conductive layer (Y) and a2 nd adhesive conductive layer (X-II) stacked in this order with a 2-sheet release sheet sandwiched therebetween.