KR101888980B1 - Adhesive composition, and adhesive tape - Google Patents

Abstract

Disclosure of the Invention An object of the present invention is to provide a pressure-sensitive adhesive composition which is excellent in stability and coatability, has a high adhesive force even after high-humidity storage, and has a high specific strength even under a high temperature environment. (A), a polar group-containing monofunctional monomer (B), a (meth) acrylic polymer (C), an initiator (D), and a straight chain (E) having a polar group at one end of the main skeleton of the structure and having an acid value and an amine value, and a filler (F).

Description

ADHESIVE COMPOSITION, AND ADHESIVE TAPE [0002]

The present invention relates to a pressure-sensitive adhesive composition, and a pressure-sensitive adhesive tape. More particularly, the present invention relates to a pressure-sensitive adhesive composition containing a pressure-sensitive adhesive component and a filler such as a thermally conductive filler or an electrically conductive filler, and an adhesive tape using the same.

BACKGROUND ART Conventionally, there has been known a thermally conductive adhesive tape comprising a pressure-sensitive adhesive layer composed of a pressure-sensitive adhesive composition containing a pressure-sensitive adhesive component and a thermally conductive filler, and a pressure-sensitive adhesive tape having an adhesive layer composed of a pressure-sensitive adhesive composition containing a pressure- Are known. These adhesive tapes may be used by attaching them to an electronic part or a box body containing it.

For example, an electronic component such as a plasma display panel (PDP), an integrated circuit (IC) chip or the like has been required to take measures against a malfunction due to a rise in temperature, . In view of the above, a heat sink such as a heat sink is mounted on a heating element such as an electronic component. However, if the thermal connection between the electronic component and the heat sink is low, sufficient cooling performance can not be obtained. Respectively.

For example, Patent Documents 1 and 2 disclose a pressure-sensitive adhesive tape comprising a (meth) acrylic monomer, a (meth) acrylic polymer, A pressure-sensitive adhesive composition comprising an initiator, and a filler having thermal conductivity is used. In Patent Documents 3 and 4, only a (meth) acrylic monomer and a polymer dispersant are used as a pressure-sensitive adhesive component while using a metal oxide or a metal hydroxide as a thermally conductive filler.

Japanese Patent Application Laid-Open No. 2001-279196 International Publication WO2005 / 42612 Japanese Patent No. 4385573 Japanese Patent No. 4228269

However, in a system including only a (meth) acrylic monomer as a pressure-sensitive adhesive component which becomes a resin component after curing as disclosed in Patent Documents 3 and 4, it is difficult to obtain a resin component having a high molecular weight when a pressure- Therefore, cohesion is insufficient. Therefore, in the system comprising a (meth) acrylic monomer having a polarizable group capable of copolymerization, means for improving the cohesive force by adding a polyfunctional (meth) acrylic monomer as a crosslinking agent and photopolymerizing the same are taken, When the monomer is copolymerized as a crosslinking polymer, the pressure-sensitive adhesive tape itself becomes hard, resulting in deterioration of adhesion. In addition, when the pressure-sensitive adhesive composition contains no (meth) acrylic polymer, the viscosity control of the pressure-sensitive adhesive composition is basically difficult, and the application of the pressure-sensitive adhesive tape to various designs is limited.

From the above viewpoint, it is preferable to use not only a (meth) acrylic monomer but also a (meth) acrylic polymer as a pressure sensitive adhesive component, as in Patent Documents 1 and 2. However, There is a problem in that the viscosity of the composition is largely changed when the composition is stored, which is inferior in stability and easily deteriorated in coating property. In addition, the pressure-sensitive adhesive composition containing such a (meth) acrylic polymer also has a problem that the pressure-sensitive adhesive composition tends to be deteriorated in a high-humidity environment, and the holding force tends to deteriorate under a high temperature environment.

An object of the present invention is to provide a pressure-sensitive adhesive composition which is excellent in stability, excellent in coating properties, has a high adhesive force even after storage under high humidity, and has a high specific force even in a high- And to provide an adhesive tape using the same.

According to one aspect of the present invention, there is provided a process for producing a poly (alkyl methacrylate), which comprises reacting a (meth) acrylic acid alkyl ester monofunctional monomer (A), a polar group-containing monofunctional monomer (B), a (meth) acrylic polymer (C) (E) having an acid value and an amine value, and a filler (F) are provided at one end of the adhesive layer.

Since the pressure-sensitive adhesive composition contains not only the (meth) acrylic polymer (C) as the pressure-sensitive adhesive component but also the positive dispersion agent (E) having a polar group at one end of the linear skeleton and having an acid value and an amine value , The contact between the filler (F) and the (meth) acrylic polymer (C) can be suppressed, and the pressure-sensitive adhesive composition can be plasticized. As a result, it is possible to obtain a pressure-sensitive adhesive composition which is excellent in stability, has a high adhesive force even after high-humidity storage, and has a high specific strength even under a high-temperature environment. In the present specification, (meth) acryl means acryl or methacryl.

The (meth) acrylic polymer (C) preferably has a weight average molecular weight of 100,000 or more, and the pressure-sensitive adhesive composition preferably contains a (meth) acrylic polymer (C) relative to the total amount of the pressure- By mass, preferably 1 to 30% by mass.

In the adhesive composition, the positive dispersion agent (E) preferably has a phosphoric acid ester salt as a polar group.

The pressure-sensitive adhesive composition contains the positive dispersion agent (E), preferably 0.5 to 7.5 parts by mass, per 100 parts by mass of the filler (F).

The amphoteric dispersing agent (E) is preferably insoluble in water and soluble in both the (meth) acrylic acid alkyl ester monofunctional monomer (A) and the polar group-containing monofunctional monomer (B) .

According to another aspect of the present invention, there is provided an adhesive tape comprising a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive composition. In the pressure-sensitive adhesive tape, the filler (F) preferably has an average particle diameter of 50% or less of the pressure-sensitive adhesive layer and a maximum particle diameter of not more than the thickness of the pressure-sensitive adhesive layer.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to obtain a pressure-sensitive adhesive composition which is excellent in stability and coating property, has a high adhesive force even after high-humidity storage, and has a high specific strength even under a high temperature environment. Therefore, the pressure-sensitive adhesive tape having the pressure-sensitive adhesive layer containing the pressure-sensitive adhesive composition can be preferably used as a heat-conductive pressure-sensitive adhesive tape or a conductive pressure-sensitive adhesive tape.

(A), the polar group-containing monofunctional monomer (B), the (meth) acrylic polymer (C), the initiator (D) (E) having a polar group at one end of the main skeleton of the structure and having an acid value and an amine value is used.

(E) having an acid value and an amine value is used, even the adhesive composition containing the filler (F) and the (meth) acrylic polymer (C), the positive dispersion agent (E) is deposited on the surface of the filler (F) The interaction between the (meth) acrylic polymer (C) and the filler (F) is suppressed, whereby the stability of the adhesive composition can be improved. In addition, the attachment of the dispersant to the surface of the filler (F) mainly functions as the acidic group portion of the polar group in which the acid value is exhibited. Since the amphoteric dispersant (E) also has a basic group portion indicating an amine value, Is bonded to the polar group of the (meth) acrylic polymer (C) by ionic bonding or the like, whereby the bleed-out can be suppressed even after high-humidity storage, and the adhesive composition can be plasticized by the positive dispersion agent (E). As a result, it is possible to obtain a pressure-sensitive adhesive composition having a high adhesive force after high-humidity storage and having a high specific strength even under a high-temperature environment. On the other hand, when a dispersant having only an acid chelate is used, contact between the (meth) acrylic polymer (C) and the filler (F) is suppressed, but when the (meth) acrylic polymer And the adhesive strength is lowered. In addition, when a dispersant having amine amines is used, the dispersant is not sufficiently adhered to the filler F, and therefore, the stability is lowered.

In addition, since the positive dispersion agent (E) has a linear main skeleton and has a polar group only at one end of the main skeleton, the interaction between the positive dispersion agent (E) and the filler (F) Is suppressed. On the contrary, in consideration of adhesion of the dispersant to the filler (F), it is also conceivable to use a dispersing agent having a comb type structure having a polar group having an acidic group portion and a basic group portion in a plurality of branched chains. When a dispersing agent is used, the interaction between the dispersing agent and the filler (F) becomes excessively strong and the compatibility is lowered, and the stability of the adhesive composition tends to deteriorate rather.

In the present embodiment, examples of the polar group of the positive dispersion agent (E) include a phosphoric acid ester salt having a phosphoric acid group and an ammonium group, and a sulfuric acid ester salt having a sulfuric acid group and an ammonium group. Among them, a phosphoric acid ester salt is preferable. The acid value by these polar groups is preferably 10 to 300 mgKOH / g, more preferably 14 to 150 mgKOH / g, still more preferably 77 to 132 mgKOH / g, and the amine value is preferably 10 to 300 mgKOH / g More preferably 20 to 150 mg KOH / g, and still more preferably 21 to 74 mg KOH / g. In the present specification, acid clog refers to the number of mg of KOH required to neutralize 1 g of the solid content of the dispersant, and means the number of mg of KOH equivalent to the amount of HCl required to neutralize 1 g of the amine crown and solid dispersant .

The straight-chain main skeleton of the positive dispersion agent (E) is preferably composed of at least one kind of polymer chain selected from the group consisting of polyethylene glycol, polyether such as polypropylene glycol, and polyester. Among these, The main skeleton containing polypropylene glycol is more preferable. When the positive dispersion agent (E) is a polymer dispersant having such a polymer chain, the weight average molecular weight of the positive dispersion agent (E) is preferably 500 to 3,000. In the present specification, the weight average molecular weight means a polystyrene reduced weight average molecular weight by GPC (gel permeation chromatography) (solvent: tetrahydrofuran). Specific examples of the positive dispersion agent (E) available on the market include DisperBYK-101, DisperBYK-106, DisperBYK-180, DISPALON DA-325, DISPALON DA-234, DISPALON 300-257 manufactured by Kusumoto Chemical Co., Ltd., and the like. Among them, it is more preferable to be soluble in both water-insoluble (meth) acrylic acid alkyl ester monofunctional monomer (A) and polar group-containing monofunctional monomer (B). Such a positive dispersion agent (E) is excellent in compatibility with a polymer of a (meth) acrylic acid alkyl ester monofunctional monomer (A) and a polar group-containing monofunctional monomer (B) Even in the case of a pressure-sensitive adhesive composition containing a high filler, an increase in viscosity can be suppressed, occurrence of voids or the like formed in the resulting pressure-sensitive adhesive layer can be reduced, and coating properties can be further improved. As such a positive dispersion agent (E), there can be mentioned a high molecular weight positive dispersion agent having polyethylene glycol in the main skeleton, and DisperBYK-106 manufactured by BICKEMIS Co., Ltd. is available on the market.

The content of the positive dispersion agent (E) is preferably 0.5 to 7.5 parts by mass based on 100 parts by mass of the filler (F). If the content of the positive dispersion agent (E) is too small, the stability tends to decrease or the adhesive force after high-humidity storage tends to deteriorate. On the other hand, if the content of the positive dispersion agent (E) is too large, the crosslinking density is lowered and the holding power under a high temperature environment tends to be lowered.

Next, another pressure-sensitive adhesive component of the present embodiment will be described in detail.

As the (meth) acrylic acid alkyl ester monofunctional monomer (A), monofunctional monomers having an alkyl group having 20 or less carbon atoms can be used. Specific examples thereof include methyl (meth) acrylate, ethyl (meth) (Meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, isoamyl (meth) acrylate, hexyl (Meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, isodecyl (meth) acrylate, lauryl Acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, and the like. Among them, at least one member selected from the group consisting of butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and isooctyl (meth) acrylate is preferable.

The content of the (meth) acrylic acid alkyl ester monofunctional monomer (A) in the total amount of the pressure-sensitive adhesive component is preferably 55 to 90 mass%, and more preferably 60 to 85 mass%. When the content of the (meth) acrylic acid alkyl ester monofunctional monomer (A) is out of the above range, the adhesive strength tends to decrease.

As the polar group-containing monofunctional monomer (B), monofunctional monomers having a polar group and an alkyl group having 20 or less carbon atoms can be used. Specific examples thereof include (meth) acrylic acid, itaconic acid, 2- Monofunctional monomers containing a carboxyl group such as monooxyethylsuccinic acid, 2- (meth) acryloyloxyethylhexahydrophthalic acid and 2- (meth) acryloyloxyethylphthalic acid; (Meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2- A hydroxyl group-containing monofunctional monomer; Monofunctional monomers containing a phosphoric acid group such as 2- (meth) acryloyloxyethyl acid phosphate and 2- (meth) methacryloyloxyethyl acid phosphate; Amino group-containing monofunctional monomers such as dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate; (Meth) acrylonitrile; a monofunctional monomer containing a nitrile group such as (meth) acrylonitrile; And nitrogen-containing monofunctional monomers such as N-vinyl-2-pyrrolidone. Among them, a monofunctional monomer containing a carboxyl group and a hydroxyl group-containing monofunctional monomer capable of forming a three-dimensional crosslinked structure by the addition of a crosslinking agent having a reactive functional group and securing a high holding power even under a high temperature environment, Containing monofunctional monomers are preferred.

The content of the polar group-containing monofunctional monomer (B) in the total amount of the pressure-sensitive adhesive component is preferably 1 to 15 mass%, and more preferably 1 to 8 mass%. When the content of the polar group-containing monofunctional monomer (B) is 1% by mass or more, a higher adhesive force can be obtained after high-humidity storage. On the other hand, if the content of the polar group-containing monofunctional monomer (B) is 15 mass% or less, a higher holding power can be obtained in a high temperature environment.

(A) or a (meth) acrylic acid alkyl ester monofunctional monomer (A) and a polar group-containing monofunctional monomer (B) described above as a monomer component as the (meth) acrylic polymer Among them, a polymer of a (meth) acrylic acid alkyl ester monofunctional monomer (A) and a carboxyl group-containing monofunctional monomer is more preferable. By using a monomer having such a polar group as a monomer component, a high cohesive force is obtained with respect to the metal member, while the stability of the pressure-sensitive adhesive composition tends to deteriorate due to the interaction with the filler (F). In the pressure- (E), a pressure-sensitive adhesive composition excellent in stability can be obtained. The (meth) acrylic polymer (C) preferably contains a monomer of the same kind as the (meth) acrylic acid alkyl ester monofunctional monomer (A) as a monomer component, and is selected from butyl (meth) acrylate, 2-ethylhexyl (Meth) acrylate, and isooctyl (meth) acrylate as a monomer component.

The weight average molecular weight of the (meth) acrylic polymer (C) is preferably 100,000 or more, and more preferably 1,000,000 to 3,000,000. By using a high molecular weight polymer, a pressure sensitive adhesive composition having a high adhesive force can be obtained. Even when such a high molecular weight polymer is used, the pressure sensitive adhesive composition of the present embodiment contains the above-mentioned positive dispersion (E) This excellent adhesive composition can be obtained.

The content of the (meth) acrylic polymer (C) in the total amount of the pressure-sensitive adhesive component is preferably 1 to 30 mass%, and more preferably 3 to 20 mass%. When the content of the (meth) acrylic polymer (C) is 1% by mass or more, a higher adhesive force can be obtained after high-humidity storage. On the other hand, when the content of the (meth) acrylic polymer (C) is 30% by mass or less, the pressure-sensitive adhesive composition has a lower viscosity, and the coating defects can be further reduced.

(Meth) acrylic polymer (C) is not particularly limited, and conventionally known bulk polymerization or solution polymerization may be used. Of these, the (meth) acrylic polymer (C) Is preferably used as the medium and the bulk polymerization method in which the removal of the solvent is unnecessary is preferable. In addition, the (meth) acrylic polymer (C) may be used in the form of a polymerized polymerized in advance, or in the form of a polymerized partial polymer in a monomer as a medium when bulk polymerization is used.

As the initiator (D), at least one selected from the group consisting of a photopolymerization initiator and a thermal polymerization initiator can be used. Specific examples of the photopolymerization initiator include 2,4,6-trimethylbenzoyldiphenylphosphine oxide (Lucirin TPO, manufactured by BASF), 2,4,6-trimethylbenzoylphenyl ethoxyphosphine oxide Lucirin TPO-L, manufactured by BASF Co., Ltd.); Amino ketones such as 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone-1 (Irgacure 369, manufactured by Chiba); (2,4,6-trimethylbenzoyl) -phenylphosphine oxide (Irgacure 819, manufactured by Chiba), bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide , CGI403); < RTI ID = 0.0 > bisacylphosphine < / RTI > Hydroxyquinone such as hydroxycyclohexyl phenyl ketone (Irgacure 184, manufactured by Chiba) and hydroxy-2-methyl-1-phenyl-propan-1-one (Darocure 1173 manufactured by Chiba); Benzophenones such as benzophenone, 2,4,6-trimethylbenzophenone and 4-methylbenzophenone; Benzyl methyl ketal (Esacure KB1, manufactured by Nippon Shiba Hegner); 2-methyl- [4- (1-methylvinyl) phenyl] propanol oligomer (Esacure KIP150, manufactured by Nippon Shiba Hegner Co., Ltd.). Specific examples of the thermal polymerization initiator include 4,4'-azobis (4-cyanovaleric acid), dimethyl 2,2'-azobis (2-methylpropionate), 2,2 Azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'- Azobis (cyclohexane-1-carbonitrile), 1 - [(1-cyano-1-methylethyl ) Azo] formamide; Cumyl hydroperoxide, cumyl peroxyneodecanoate, cyclohexanone peroxide, 1,1,3,3-tetramethyl butyl peroxyneodecanate, octanoyl peroxide, lauroyl peroxide, 3,5,5 Butyl peroxypivalate, t-butyl peroxy-2-ethylhexanoate, t-butyl peroxyisobutylate, t-butyl cumyl peroxide, t-butyl Peroxide type thermal polymerization initiators such as peroxyneoheptanoate, 1,1-bis (t-hexylperoxy) cyclohexane, diisopropylperoxydicarbonate, 3-chlorobenzoic acid and the like.

The content of the initiator (D) is preferably 0.05 to 5% by mass, and more preferably 0.1 to 3% by mass, based on the total amount of the pressure-sensitive adhesive component. If the content of the initiator (D) is 0.05% by mass or more, a higher holding power can be obtained in a high temperature environment. On the other hand, when the content of the initiator (D) is 5% by mass or less, the increase in the low molecular weight component is suppressed, and a higher adhesive force can be obtained after the high humidity storage.

The pressure-sensitive adhesive composition of the present embodiment may further contain a crosslinking agent as one of the pressure-sensitive adhesive components. As such a crosslinking agent, it is possible to use a crosslinking agent having a functional group capable of crosslinking reaction in the molecule and by irradiation and / or heating, a (meth) acrylic acid alkyl ester monofunctional monomer (A), a polar group-containing monofunctional monomer (B) (Meth) acryl-based polymer (C) having a hydroxyl group and a hydroxyl group. The crosslinkable functional group is not particularly limited, and examples thereof include a vinyl group, a carboxyl group, an epoxy group, an isocyanate group, and a hydroxyl group. Specific examples of such a crosslinking agent include a polyfunctional polymerizable compound, an epoxy crosslinking agent, and an isocyanate crosslinking agent. Among them, a multifunctional polymerizable compound that is crosslinked by radical polymerization and does not decrease the polar group of the monofunctional monomer (B) containing a polar group is preferable.

As the polyfunctional polymerizable compound, there can be used a polyfunctional monomer or polyfunctional oligomer having two or more polymerizable double bonds such as a (meth) acrylate group, an allyl group and a vinyl group in the molecule and capable of radical polymerization . Specific examples thereof include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) (Meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, (Meth) acrylate, trimethylolpropane di (meth) acrylate, trimethylolpropane tri (meth) acrylate, allyl (meth) acrylate, vinyl Acrylate, urethane (meth) acrylate, urethane di (meth) acrylate and epoxy ester di (meth) acrylate. These may be used alone or in combination.

As the epoxy crosslinking agent, a compound having two or more epoxy groups in the molecule can be used. Specifically, for example, an epoxy resin of bisphenol A epichlorohydrin type, ethylene glycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6 Hexanediol glycidyl ether, trimethylolpropane triglycidyl ether, diglycidyl aniline, diamine glycidyl amine, N, N, N ', N'-tetraglycidyl-m-xylylenediamine, 1,3-bis (N, N'-diamine glycidylaminomethyl) cyclohexane, and the like. These may be used alone or in combination.

As the isocyanate crosslinking agent, a compound having two or more isocyanate groups in the molecule can be used. Specific examples thereof include tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, tetramethyl Xylylene diisocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate, polymethylene polyphenyl isocyanate, and adducts thereof with polyols such as trimethylolpropane. These may be used alone or in combination.

The content of the crosslinking agent is preferably 0.05 to 5% by mass, and more preferably 0.1 to 4% by mass in the total amount of the pressure-sensitive adhesive component. If the content of the crosslinking agent is 0.05 mass% or more, a higher holding force can be obtained in a high temperature environment. On the other hand, when the content of the crosslinking agent is 5 mass% or less, the increase of the low molecular weight component is suppressed, and a higher adhesive force can be obtained after the high humidity storage.

In the present embodiment, various fillers such as a heat conductive filler, an electrically conductive filler, an insulating filler, and an insulating filler can be used as the filler F in accordance with the characteristics of the intended adhesive tape. Specific examples thereof include aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, calcium oxide, magnesium oxide, zinc oxide, aluminum oxide, crystalline silica, amorphous silica, titanium oxide, Nickel, iron oxide, copper oxide, boron nitride, aluminum nitride, silicon nitride, carbon, graphite, silicon carbide, aluminum borate whisker and the like. These may be used alone or in combination. The content of the filler (F) is not particularly limited, but is usually 50 to 300 parts by mass based on 100 parts by mass of the pressure-sensitive adhesive component.

It is preferable that the filler (F) has an average particle diameter of 50% or less of the thickness of the pressure-sensitive adhesive layer and a maximum particle diameter of not more than the thickness of the pressure-sensitive adhesive layer when the pressure-sensitive adhesive tape having the pressure- When the filler F having such an average particle diameter and a maximum particle diameter is used, generation of voids or streaks at the time of coating can be further reduced.

In the present embodiment, if the pressure-sensitive adhesive composition contains the above-mentioned pressure-sensitive adhesive component and the filler (F), for the purpose of improving other properties, a pressure- May further contain an additive.

As a method of producing the adhesive composition of the present embodiment, conventionally known methods can be used. For example, a method of mixing the components (A) to (E) with the filler (F) by a conventionally known stirring means can be adopted. When the (meth) acrylic polymer (C) prepared by the bulk polymerization method is used, a polymer-containing solution (A) containing the alkyl (meth) acrylate monomer (A) and the polar group-containing monofunctional monomer May be used.

As a method of manufacturing the adhesive tape of the present embodiment, a conventionally known method can be used. For example, the pressure-sensitive adhesive composition obtained as described above is coated on at least one surface of a substrate to form a pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer is irradiated with radiation (X-ray, ultraviolet ray, electron beam, etc.) The adhesive tape can be produced.

As the substrate, a substrate made of plastic, metal, paper or the like can be mentioned, and among these, a plastic substrate made of polyethylene terephthalate, polypropylene and the like is preferable. These substrates may be subjected to surface treatment such as peelability improving treatment. The thickness of the pressure-sensitive adhesive layer is preferably 50 to 250 占 퐉 in order to reduce the thickness of the adherend after adhering the pressure-sensitive adhesive layer. Further, a peeling sheet may be further formed on the pressure-sensitive adhesive layer. Specific examples of the means for irradiating the radiation include black light, a chemical lamp, a low-pressure mercury lamp, a high-pressure mercury lamp, and a metal halide lamp. When ultraviolet rays are used as the radiation, the intensity of the ultraviolet rays is preferably about 0.1 to 10 mW / cm 2 (wavelength: 365 nm), and the irradiation time is preferably 20 seconds to 5 minutes.

In addition, the adhesive tape needs to have a high adhesive force capable of firmly fixing the adherend on the upper and lower surfaces of the pressure-sensitive adhesive layer. In consideration of the case where the adhering tape is mistakenly adhered or foreign matter is adhered to the adherend surface, , It is preferable that the pressure-sensitive adhesive layer is excellent in lithheet workability so that the pressure-sensitive adhesive layer can be peeled from the adherend and reattached. The pressure-sensitive adhesive composition of the present embodiment has such a good workability that the pressure-sensitive adhesive layer can be easily peeled off from the adherend immediately after adhering to the adherend, Can be formed.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In the following, what is referred to as " part " means " part by mass ".

Example

(Meth) acrylic acid alkyl ester monofunctional monomer, a polar group-containing monofunctional monomer, a crosslinking agent, a photopolymerization initiator, a dispersant, and a filler shown in Table 1 were prepared as the constituent components of the adhesive composition. The maximum particle size and average particle size of the filler are measured values by a laser diffraction particle size distribution analyzer (microtrack HRA). The solubility of the dispersant in water and each (meth) acrylic monomer is determined by the following evaluation. The abbreviated names in Table 2 indicate the same components as the abbreviated names in Table 1.

[Solubility in water]

Insoluble: Under room temperature, the dissolution amount per 100 g of water is less than 20 g

Solubility: The dissolution amount per 100 g of water at room temperature is 20 g or more

[Solubility in (meth) acrylic monomer]

Insoluble: Under a room temperature, the dissolution amount per 100 g of each (meth) acrylic monomer is less than 20 g

Solubility: Under a room temperature, the dissolution amount per 100 g of each (meth) acrylic monomer is 20 g or more

<Preparation of (meth) acrylic polymer>

450 parts of 2-ethylhexyl acrylate (2EHA), 50 parts of acrylic acid (AA) and 2 parts of 2-benzyl-2 as a photopolymerization initiator were placed in a four-necked flask equipped with a thermometer, a stirring propeller, (Irgacure 369, manufactured by Ciba-Geigy Co., Ltd.) was put into the flask, and the temperature of the flask was adjusted to 50 캜. (Hereinafter abbreviated as Poly-2EHA / AA) composed of 2 EHA and AA and 2 EHA and AA of unreacted component were added to the solution for 30 minutes while irradiating the solution, Containing syrup. The content of Poly-2 EHA / AA in the obtained syrup was 20 mass% and the weight average molecular weight was 1 million.

&Lt; Preparation of pressure-sensitive adhesive composition &

Each constituent component was mixed and stirred so as to be the blending amount shown in Table 2, and each pressure-sensitive adhesive composition was prepared. The numerical value in parentheses in the compounding amount of the dispersing agent is the compounding amount per 100 parts of the filler.

&Lt; Production of pressure-sensitive adhesive tape &

Each of the pressure-sensitive adhesive compositions prepared above was coated on one surface of a polyester film (thickness: 50 占 퐉) subjected to the peeling treatment to a thickness shown in Table 2 by a knife coater to form a pressure-sensitive adhesive layer, The polyester film (thickness: 50 占 퐉) subjected to the peeling treatment was superposed so as not to contain air bubbles and irradiated with ultraviolet rays (intensity at a wavelength of 365 nm: 3 mW / cm2) from one side of the pressure sensitive adhesive layer for 2 minutes, Respectively.

The following evaluations were carried out using the pressure-sensitive adhesive composition and the pressure-sensitive adhesive tape thus obtained. Table 3 shows the evaluation results of these.

〔stability〕

(25 占 폚) immediately after preparation of the pressure-sensitive adhesive composition and a viscosity after storage (24 占 폚) after the pressure-sensitive adhesive composition was stored at 40 占 폚 for 24 hours using a B type viscometer (manufactured by Shibaura Systems, single cylinder rotary viscometer, 25 占 폚), and viscosity increase / decrease rate were measured.

〔adhesiveness〕

A test sample having a pressure-sensitive adhesive layer adhered on a test plate made of SUS304 was prepared. The test samples were stored for 24 hours under an environment of 23 占 폚 and 50% RH and then subjected to an initial adhesive force and an adhesive tape stored for 100 hours under a high humidity environment of 65 占 폚 and 95% RH. The adhesive force after storage of the measurement sample with the pressure-sensitive adhesive layer adhered thereto was measured according to JIS Z 0237.

〔retention〕

The test samples prepared in the same manner as in the adhesion test were used and the test samples were stored for 168 hours under a high temperature environment of 80 DEG C and 120 DEG C respectively and the retention of the pressure-sensitive adhesive layer after storage was measured according to JIS Z 0237, The retention force was evaluated on the basis of.

○: No deviation occurs in the pressure-sensitive adhesive layer

X: Deviation and dropping occurred in the pressure-sensitive adhesive layer

[Thermal Conductivity]

A test specimen with an adhesive tape applied to a predetermined thickness so as to have a total thickness of 1 mm was prepared and the thermal conductivity of the specimen was measured by a rapid thermal conductivity meter (QTM-500, manufactured by Kyoto Electronics Co., Ltd.).

[Appearance (stripe)]

The pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape thus prepared was visually observed, and it was evaluated whether or not there was a portion to which the pressure-sensitive adhesive composition was not applied (defects in stripes).

[Appearance (void)]

The pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape thus prepared was observed with an optical microscope (Digital Microscope, VHX-500F, manufactured by KYENS Corporation), and it was evaluated whether or not there was a portion (void) not coated with the pressure-sensitive adhesive composition.

As shown in the above table, it can be seen that the pressure-sensitive adhesive composition of the examples shows little change in the viscosity of the pressure-sensitive adhesive composition after storage and can form a pressure-sensitive adhesive layer without any apparent problems. Further, it can be seen that the pressure-sensitive adhesive composition not only has a high adhesive force even after high-humidity storage, but also has a high specific strength even under a high-temperature environment. Particularly, in the case of using an amphoteric dispersant that is insoluble in water and soluble in both the (meth) acrylic acid alkyl ester monofunctional monomer and the polar group-containing monofunctional monomer, a filler having a small particle size can be used, It is understood that even when a layer is formed, the coatability is excellent.

On the other hand, it can be seen that the pressure-sensitive adhesive composition that does not contain a positive dispersion agent thickens the pressure-sensitive adhesive composition after storage and gels the pressure-sensitive adhesive composition to such an extent that it becomes impossible to coat. In the case of using a dispersant having a comb-like structure, even if it has both a dispersant having an amine-ambiguity and an acid value and an amine value, as in the case of not using a dispersant, the viscosity of the adhesive composition is increased after storage, Able to know. It is considered that this is because the interaction between the filler and the (meth) acrylic polymer can not be sufficiently inhibited even when a dispersant having amine amines is used. Further, when a dispersant having a comb-like structure is used, it is considered that the interaction between the dispersant and the filler is increased.

On the other hand, in the case of using a dispersing agent having only an acid chelate, the viscosity change is small, but the adhesive force after the high-humidity storage is remarkably lowered. It is considered that this is because the (meth) acrylic polymer bleeds out onto the surface of the pressure-sensitive adhesive layer.

In addition, the pressure-sensitive adhesive composition not containing the (meth) acrylic polymer in the pressure-sensitive adhesive composition has a very low viscosity, which causes the pressure-sensitive adhesive composition to sag upon coating with a knife coater, It is difficult to stably coat the composition. In addition, the adhesive tape had insufficient adhesive force and retaining force. This is considered to be because the (meth) acrylic polymer is not contained in the pressure-sensitive adhesive composition. Therefore, the pressure-sensitive adhesive composition not containing the (meth) acrylic polymer is very difficult to adjust the optimum viscosity according to the coating method, and thus the design and coating method of the pressure-sensitive adhesive composition is limited, and also is inferior in characteristics.

Further, when a filler having a largest maximum particle diameter with respect to the thickness of the pressure-sensitive adhesive layer is used, streaks are formed on the pressure-sensitive adhesive layer during coating and the appearance becomes poor.

Claims (12)

(A), a polar group-containing monofunctional monomer (B), a (meth) acrylic polymer (C), an initiator (D), and a polar group at the terminal end of a linear skeleton of the alkyl (meth) A pressure-sensitive adhesive composition comprising a pressure-sensitive adhesive component comprising at least an amphoteric dispersant (E) having an acid value and an amine value and insoluble in water, and a filler (F). The method according to claim 1,
The (meth) acrylic polymer (C) has a weight average molecular weight of 100,000 or more. 3. The method according to claim 1 or 2,
Wherein the pressure-sensitive adhesive composition contains 1 to 30 mass% of the (meth) acrylic polymer (C) based on the total amount of the pressure-sensitive adhesive component. 3. The method according to claim 1 or 2,
The positive-working dispersant (E) has a phosphoric acid ester salt as the polar group. 3. The method according to claim 1 or 2,
Wherein the positive dispersion agent (E) is contained in an amount of 0.5 to 7.5 parts by mass based on 100 parts by mass of the filler (F). 3. The method according to claim 1 or 2,
Wherein the positive dispersion agent (E) is insoluble in water and soluble in both of the (meth) acrylic acid alkyl ester monofunctional monomer (A) and the polar group-containing monofunctional monomer (B). A pressure-sensitive adhesive tape comprising a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive composition according to claim 1 or 2. A pressure-sensitive adhesive tape provided with a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive composition according to claim 3. A pressure-sensitive adhesive tape comprising a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive composition according to claim 4. A pressure-sensitive adhesive tape comprising a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive composition according to claim 5. A pressure-sensitive adhesive tape provided with a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive composition according to claim 6. 8. The method of claim 7,
Wherein the filler (F) has an average particle diameter of 50% or less of the thickness of the pressure-sensitive adhesive layer and has a maximum particle diameter equal to or less than the thickness of the pressure-sensitive adhesive layer.