JPH11343478A - Pressure sensitive curing adhesive, sheet having curing tackiness and method for adhesion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare a pressure sensitive curing adhesive composition, having a pressure sensitive adhesive property in an initial state, having a longer pot life after being irradiated with light, and capable of hardening at comparatively low temperatures in a short time, by including a specific polymer, a specific compound and a specific polymerization initiator. SOLUTION: This adhesive composition is prepared by including (A) a polymer having tackiness, (B) a cationically polymerizable compound and (C) a photopolymerization initiator, wherein at least one of the constituents A and B has nitrogen in each molecule, and the total content of nitrogen is adjusted so as for the ratio of mol equivalent of nitrogen to that of cation formed from the constituent C when irradiated with light to become >=1. An acrylic polymer having the transition temperature <=20 deg.C and the weight average molecular weight 10,000-5,000,000 and an epoxy group-containing compound are pref. as the constituents A and B respectively. The constituent C is activated with the irradiation of ultraviolet light having the wavelength 200-400 nm and releases cationic photopolymerization-initiating substances.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photocurable curable adhesive composition which exhibits pressure-sensitive adhesiveness in an initial state and cures after light irradiation, a curable adhesive sheet, and a cured adhesive sheet. Regarding the bonding method, more specifically, a curable adhesive composition having a sufficient pot life and capable of curing at a relatively low temperature and in a short time, a curable adhesive sheet, and adhesion using the same About the method.

[0002]

2. Description of the Related Art Since adhesives exhibit pressure-sensitive adhesiveness in the initial state, like adhesives, they can be applied to adherends with a relatively low pressure and cured by any method after application. Thereby, an adhesive strength equivalent to that of the adhesive is exhibited. Such adhesives have attracted attention as an alternative to adhesives in recent years because of their excellent adhesive workability and physical properties after adhesive curing.

[0003] As a curing method for the above-mentioned adhesives,
Methods using various means such as heat, light or moisture have been proposed. Among them, a curing method using light can be used for bonding an adherend having low heat resistance. Can be suitably used for bonding.

For example, Japanese Patent Application Laid-Open No. Hei 7-138550 discloses a liquid epoxy resin, a crosslinked rubber particle, and a latent curing agent, which exhibits tackiness when applied, and which is cured by heat, photoradical, photocation or moisture after application. A pressure-sensitive adhesive which is cured by a curing method using is disclosed. It is stated that various curing methods can be employed as described above depending on the type of the latent curing agent. In addition, the use of the crosslinked rubber particles enhances the initial pressure-sensitive adhesiveness.

Further, in recent years, attention has been paid to adhesives of the type in which light is irradiated prior to application and cured by utilizing photocationic polymerization. In photocationic polymerization, unlike photoradical polymerization, which has been the mainstream in conventional photocurable adhesives, the curing reaction continues even after light irradiation. Therefore, since the adhesive can be applied to the adherend after light irradiation and cured,
It can also be applied to opaque adherends.

An example of the above-mentioned adhesive utilizing photocationic polymerization is disclosed in JP-A-9-279103. Here, a high-molecular-weight polymer having tackiness, an epoxy resin, and a cationic photopolymerization initiator are included, and the photocationic polymerization initiator is activated by irradiation with light, and is cured by ring-opening polymerization of epoxy groups of the epoxy resin. It is supposed to progress.

[0007]

The conventional adhesives have a disadvantage that the curing time is long when they are cured by using, for example, heat. In order to shorten the curing time, it is necessary to apply high heat, so that it cannot be applied to an adherend having insufficient heat resistance.

[0008] In the case of an adhesive which is cured by utilizing photoradical polymerization, it can be cured in a relatively short time. However, when the irradiation of light is stopped, the curing reaction is stopped. Therefore, it could not be used for bonding opaque adherends.

On the other hand, as disclosed in Japanese Patent Application Laid-Open No. 9-279103, when light is irradiated prior to bonding to promote photocationic polymerization and cure, materials having low heat resistance or opaque materials are used. Although it can be applied to an adherend made of a material, cationic photopolymerization proceeds continuously even after the stop of light irradiation. Therefore, it gradually cures even after the light irradiation is stopped, and after a certain period of time, the tackiness decreases,
There has been a problem that it can no longer be attached to an adherend. Therefore, it was necessary to continuously perform from the light irradiation to the attachment in as short a time as possible.

[0010] However, in the above-mentioned adhesive using photocationic polymerization, it is also possible to adjust the time (pot life), ie, the pot life, that can be stuck after application of light, in order to maintain the adhesive property. It is. However, when the pot life is lengthened, the curing speed decreases, and it takes a long time to cure.

An object of the present invention is to solve the above-mentioned drawbacks of the prior art, to have a pressure-sensitive adhesive property in an initial state, to have a long pot life after light irradiation, to cure at a relatively low temperature and for a short time. The present invention provides a curable adhesive composition, a curable adhesive sheet, and a bonding method using the curable adhesive sheet which can be applied to an adherend having insufficient heat resistance. It is in.

[0012]

According to a first aspect of the present invention, there is provided a curable adhesive composition comprising a tacky polymer, a cationically polymerizable compound, and a cationic photopolymerization initiator.
And at least one of the adhesive polymer and the cationically polymerizable compound has a nitrogen atom in the molecule, and the molar equivalent of the nitrogen atom and hydrogen generated from the cationic photopolymerization initiator when irradiated with light. It is characterized by containing a nitrogen atom such that the ratio to the molar equivalent of the ion is 1 or more.

According to a second aspect of the present invention, there is provided a curable adhesive composition comprising a tacky polymer, a cationically polymerizable compound, a compound having a nitrogen atom in a molecule, and a cationic photopolymerization initiator. Wherein the nitrogen atom is contained such that the ratio of the molar equivalent of the nitrogen atom to the molar equivalent of the cation generated from the cationic photopolymerization initiator when irradiated with light is 1 or more. .

The third aspect of the present invention is a curable adhesive sheet obtained by molding the curable adhesive composition according to the first or second aspect into a sheet. Claim 4
In the curable pressure-sensitive adhesive sheet according to the invention described in (1), light is irradiated prior to sticking.

According to a fifth aspect of the present invention, there is provided a bonding method using the curable pressure-sensitive adhesive sheet according to the third or fourth aspect, wherein the adherends are adhered to each other using the curable pressure-sensitive adhesive sheet. In this case, heating is performed at the time of bonding or after bonding.

Hereinafter, the present invention will be described in detail. In the curable adhesive composition according to the present invention, the pressure-sensitive adhesive in the initial state can be obtained by the above-mentioned tacky polymer. In addition, the light cationic polymerization initiator is activated by the irradiation of light,
The cationically polymerizable compound undergoes cationic polymerization by the generated cation, and is cured. In this case, if the ratio of the molar equivalent of the nitrogen atom of at least one type of atomic group containing a nitrogen atom to the molar equivalent of the photocationic polymerization initiator is 1 or more, the cation generated by the atomic group is trapped, The cation and the cation polymerizable compound are stably coexisted in the composition without cation polymerization immediately after the light irradiation. Therefore, since the adhesiveness is maintained at room temperature for a sufficiently long time, the time that can be applied to the adherend, that is, the pot life can be sufficiently long. In order to further increase the pot life and enhance the storage stability, the molar equivalent ratio is set to 1
It is preferably 0 or more.

The curable pressure-sensitive adhesive composition and the curable pressure-sensitive adhesive sheet according to the present invention may be irradiated with light before or after application, or may be irradiated with light before production.
The cation and the cationic photopolymerizable compound may be coexisted. Even when light irradiation cannot be performed stably during use, light can be irradiated in advance during manufacturing as described above, so that bonding work on site can be facilitated, and for large adherends. Can also be easily applied.

The light irradiation is carried out by irradiating light having an active wavelength of the cationic photopolymerization initiator from an appropriate light source. Ultraviolet light is preferably used as the light having the active wavelength, and a high-pressure mercury lamp, a metal halide lamp, a chemical lamp, or the like can be used as a light source.

The above-mentioned light irradiation needs to be performed at an illuminance capable of activating the cationic photopolymerization initiator and generating cations, and the required adhesive properties and heat resistance are exhibited in the final cured adhesive product. It is preferable to set the light irradiation amount as described above.

In the curable pressure-sensitive adhesive composition and the curable pressure-sensitive adhesive sheet after light irradiation, cations are trapped by heating at a relatively low temperature at an arbitrary point after sticking to an adherend. The trapping action of the nitrogen-containing atomic group can be reduced or eliminated. Therefore, when the cations are not trapped, the cationic polymerization proceeds in a very short time, and the bonding strength becomes extremely high in a short time after the above heating. In this case, the higher the cation concentration generated by the activation of the photocationic polymerization initiator, the faster the curing proceeds.

The heating temperature is not particularly limited, but is preferably in the range of 50 to 100 ° C. If the temperature is lower than 50 ° C., the storage stability at room temperature is reduced, and
If the temperature is higher than 00 ° C., it may be difficult to apply to an adherend having low heat resistance. However, when a heat-resistant material is attached, the material may be heated to 100 ° C. or more.

The atomic group containing a nitrogen atom is not particularly limited, but may be -CN, -NRCO
It is preferable to use a functional group selected from-or -NRCO-O- (where R represents H or an aliphatic, alicyclic or aromatic hydrocarbon group). In these functional groups, the generated cations can be stably trapped due to the electron donating property of the nitrogen atom, and when heated to a relatively low temperature, the trapping action is reduced or lost.

The storage of the curable pressure-sensitive adhesive composition and the curable pressure-sensitive adhesive sheet according to the present invention is determined by the reaction temperature of the composition. .

(Cured Adhesive Composition) A: Adhesive Polymer The above-mentioned adhesive polymer is blended to exhibit pressure-sensitive adhesiveness.
Although not particularly limited, an adhesive polymer used for a general rubber-based, acrylic-based, or silicone-based adhesive can be used. In particular, an acrylic polymer is preferably used because the polymer alone has adhesiveness.

The acrylic adhesive polymer includes:
In the present invention, an acrylic polymer containing an alkyl acrylate having a low glass transition point as a main component is preferably used because the polymer alone can exert appropriate pressure-sensitive adhesiveness. As the acrylic polymer, those having a glass transition point Tg of 20 ° C. or less are more preferable because of good initial tackiness, and those having a glass transition point Tg of 0 ° C. or less are more preferably used.

When the acrylic adhesive polymer is used, the molecular weight is not particularly limited, but is preferably in the range of 10,000 to 5,000,000, more preferably 100,000 to 300 in terms of weight average molecular weight. Range of ten thousand. When the molecular weight is less than 10,000, tackiness and heat resistance may be insufficient. When the molecular weight exceeds 5,000,000, viscosity increases, coating properties decrease, thickness accuracy decreases, and productivity decreases. Sometimes.

Preferred acrylic polymers include, for example, homopolymers or copolymers of alkyl (meth) acrylate monomers having an alkyl group having 2 to 14 carbon atoms, and more preferably the above alkyl ( A copolymer of a (meth) acrylate monomer and another vinyl monomer copolymerizable with the alkyl (meth) acrylate monomer can be exemplified.

The alkyl (meth) acrylate monomers include ethyl acrylate and n-butyl (meth)
Examples thereof include acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, and isomyristyl acrylate.

The vinyl monomer is not particularly limited as long as it is a compound copolymerizable with the alkyl (meth) acrylate monomer, and may be a (meth) acrylate other than the alkyl (meth) acrylate, vinyl acetate, styrene, Vinyl chloride, ethylene, propylene, 2
-Hydroxyethyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, ε-caprolactone (meth) acrylate, 2-acryloyloxyethyl succinic acid, (meth) acrylonitrile, N-vinylpyrrolidone, isobornyl (meth) acrylate, N -Acryloyl morpholine, benzyl (meth) acrylate,
Glycidyl (meth) acrylate, N-vinylcaprolactone, N-vinylpiperidine, (meth) acrylic acid,
Maleic anhydride, crotonic acid, itaconic acid and the like can be mentioned.

As the adhesive polymer, silicones such as a mixture of a silicone rubber such as polydimethylsiloxane and polydiphenylsiloxane and a silicone resin such as polysiloxane having trimethylsilyl group or triphenylsilyl group; polyesters Polyurethanes; Polyethers; Polycarbonates; Polyvinyl ethers; Polyvinyl alcohol; Non-acrylic polymers such as polyisobutylene, acrylic rubber, acrylonitrile-butadiene rubber, random styrene-butadiene rubber, butyl rubber, isoprene rubber; Butadiene rubber, ethylene-propylene rubber, ethylene-propylene-diene rubber, urethane rubber, styrene-isoprene-styrene block rubber, styrene-ethylene - butadiene - styrene block rubbers, styrene - may be a synthetic rubber-based polymers such as butadiene block rubber.

B: Cationic Polymerizable Compound (Cationic Polymerizable Compound) In the present invention, a cationically polymerizable compound is blended in order to cure the curable adhesive composition by irradiating it with light. As the cationically polymerizable compound, various monomers, oligomers or polymers having a cationically polymerizable functional group in a molecule, for example, a hydroxyl group, a vinyl ether group, an episulfide group, an ethyleneimine group or an epoxy group can be used.
Further, the polymer having these functional groups is not limited, and various polymers such as acrylic, urethane, polyester, polyolefin, polyether, natural rubber, block copolymer rubber, and silicone can be used. it can.

The above-mentioned cationically polymerizable compounds may be used alone or in combination of two or more. As the cationic polymerizable compound, a compound having an epoxy group is preferably used. Since ring-opening polymerization of an epoxy group has high reactivity and a short curing time, the bonding step can be shortened. Furthermore, since the cohesive force and the elastic modulus are high, it is possible to obtain an adhesive cured product having excellent heat resistance and adhesive strength, for example, in a process exposed to high heat such as soldering in a process of manufacturing a printed circuit board or a flexible printed board. In addition, adhesion abnormalities such as peeling and displacement can be effectively prevented.

As the compound having an epoxy group,
Epoxy resins are preferably used. Examples of the epoxy resin include bisphenol A type, bisphenol F type, phenol novolak type, cresol novolak type, glycidyl ether type, and glycidylamine type epoxy resins.

An epoxy group-containing oligomer (for example, manufactured by Yuka Shell Epoxy Co., Ltd., trade name: Epicoat 10)
01, Epicoat 1002, etc.) are also preferably used.
Further, an addition polymer of the above-mentioned epoxy group-containing monomer or oligomer may be used, and examples thereof include glycidylated polyester, glycidylated polyurethane, and glycidylated polyacrylate.

In particular, an acrylic polymer such as a glycidylated polyacrylate containing an epoxy group has a high compatibility with the acrylic adhesive polymer as described above.
preferable. Such an acrylic polymer is obtained by a method in which epichlorohydrin is reacted with an acrylic polymer having an OH group, or a method in which glycidyl (meth) acrylate is copolymerized.

Further, other resin components and the like may be blended or added to the cationically polymerizable compound to improve flexibility and crack resistance, and to improve adhesion and bending strength. Examples of such a modified product include a CTBN (butadiene-acrylonitrile rubber containing a terminal carboxyl group) modified epoxy resin; an epoxy resin in which various rubbers such as acrylic rubber, NBR, SBR, butyl rubber, or isoprene rubber are dispersed; Epoxy resins modified with various liquid rubbers; epoxy resins obtained by adding various resins such as acryl, urethane, urea, polyester, and styrene; chelate-modified epoxy resins; and polyol-modified epoxy resins.

The cationically polymerizable compound may be modified with another functional group, if necessary, or may have a reactive functional group such as a compound having a radically polymerizable unsaturated bond introduced therein. Is also good.

The polysulfide-modified epoxy is a compound having a polysulfide skeleton in the main chain and having epoxy groups at both ends. The urethane-modified epoxy is a resin obtained by introducing a urethane bond into an epoxy resin skeleton. Examples of the method for producing this urethane-modified epoxy resin include a method in which a hydroxyl group of a compound having both epoxy and hydroxyl groups in the molecule and an isocyanate group of the urethane prepolymer are reacted to introduce a urethane bond into the epoxy group resin. Can be.

The above urethane prepolymer is OCN-
A polymer obtained by reacting a polyisocyanate compound represented by a general formula such as U-NCO with a polyhydroxy compound represented by a general formula such as HO-R'-OH.

Here, U and R 'are aliphatic, aromatic,
Examples thereof include an alicyclic hydrocarbon chain, a polyether chain, a polyester chain, and a complex chain thereof, but these are not necessarily required.

The urethane prepolymer obtained by reacting the urethane prepolymer thus obtained with the hydroxyl group of a compound having both epoxy and hydroxyl groups in the molecule is called urethane-modified epoxy.

For example, a linear urethane-modified epoxy is obtained by reacting a hydroxyl group such as glycidol or a resol having an epoxy group with a urethane prepolymer.
As the branch type urethane-modified epoxy, a hydroxyl group such as a pisphenol type epoxy resin was reacted with a urethane prepolymer, and as the acrylic urethane-modified epoxy resin, a hydroxyl group of a hydroxy acrylate was reacted with a urethane prepolymer. Things.

Specifically, for example, Asahi Denka Co., Ltd., trade names: EPU-6, EPU-15, EPU-16A, EP
U-16B, EPU-17T-6, EPU-4, EPU
-75X, EPU-86, EPU-73, EPU-7
8, EPU-11.

In the present invention, vinyl ethers and OH group-containing compounds can also be suitably used as the cationically polymerizable compound. Examples of the vinyl ether include vinyl ethyl ether, vinyl methyl ether, vinyl isopropyl ether, vinyl-n-propyl ether, vinyl isobutyl ether, vinyl-n-butyl ether, and vinyl-
Examples thereof include n-mil ether, vinyl isoamyl ether, vinyl-2-ethylhexyl ethyl, and vinyl-n-octadecyl ether.

Examples of the OH group-containing compound include glycol,
Glycerin, diglycerin, polyglycerin, polyethylene glycol, polypropylene glycol, polyvinyl alcohol, OH group-containing polyester resin, terminal OH
A base urethane resin or the like can be suitably used.

In the first aspect of the present invention, A: an adhesive polymer and / or B: a cationically polymerizable compound contains a nitrogen atom. The sex compound will be described later.

C: Photocationic Polymerization Initiator In the present invention, the photocationic polymerization initiator is activated by irradiation with light to generate a photocationic polymerization initiator, and has a relatively low energy. The polymerization can be started.

As the light, microwaves, infrared rays, visible light, ultraviolet rays, X-rays, γ-rays and the like can be used. Generally, the handling is easy and simple, and relatively high energy can be obtained. Ultraviolet rays that can be used are preferably used. More preferably, ultraviolet light having a wavelength of 200 to 400 nm is used.

The ultraviolet rays can be irradiated using an appropriate light source such as a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, and a chemical lamp. The cationic photopolymerization initiator may be either an ionic photoacid generating type or a nonionic photoacid generating type.

The ionic photoacid generating types include onium salts such as aromatic diazonium salts, aromatic halonium salts, and aromatic sulfonium salts, and organic metal salts such as iron-allene complexes, titanocene complexes, and arylsilanol-aluminum complexes. Complexes and the like can be mentioned. More specifically, for example, Optomer SP-150 (manufactured by Asahi Denka), Optmer SP-170 (manufactured by Asahi Denka), UVE
-1014 (manufactured by General Electronics), CD-
Commercially available initiators such as 1012 (manufactured by Sartomer) can be used.

As the nonionic photoacid generating type, nitrobenzyl ester, sulfonic acid derivative, phosphoric acid ester, sulfonic acid derivative, phenolsulfonic acid ester, diazonaphthoquinone, N-hydroxyimidesulfonate and the like can be used. it can.

The above-mentioned cationic photopolymerization initiators may be used alone or in combination of two or more, and are cured in a plurality of stages using a plurality of cationic photopolymerization initiators having different effective active wavelengths. Is also good.

The cationic photopolymerization initiator is used in an amount of 0.001 mol based on 1 mol of the functional group of the cationic photopolymerizable compound in the curable adhesive composition of the present invention.
% Is preferable. When the amount is less than 0.001 mol%, the cationic photopolymerization does not sufficiently proceed, and the curing speed may be slow.

(Compound Containing Nitrogen Atom) The curable adhesive composition according to the present invention contains a nitrogen atom, and the molar equivalent of the nitrogen atom and the photocationic polymerization when irradiated with light. The ratio to the molar equivalent of hydrogen ions generated from the initiator is set to 1 or more.

According to the second aspect of the present invention, a compound containing a nitrogen atom is used. Examples of the compound containing a nitrogen atom include compounds having at least one type of atomic group containing a nitrogen atom. Phenylamine, naphthylamine, dialkylamine, diphenylamine, dinaphthylamine, trialkylamine, triphenylamine, trinaphthylamine, monoalcoholamines, dialcoholamines, trialcoholamines, pyrrole, 2-pyrroline, pyrrolidine, pyrazole, -Pyrazoline, pyrazolidine, imidazole, 2
-Imidazolines, imidazolidines, triazoles, tetrazoles, isoxazole, furazane, isocyanazole, thiazole, pyridine, piperidine, pyridazine, pyrimidine, pyrazine, piperazine, triazine,
Tetrazine, 4H-1,4-oxazine, 4H-1,4
-Including heterocycles such as thiazine, indole, indoline, isoindole, isoindoline, indolizine, 1H-indazole, 2H-indazole, benzimidazole, benzotriazole, benzoxazole, benzothiazole, pyrrolidone, oxazoline, morpholine and the like. Compounds, azo compounds and the like: polyamide resins, urethane resins, acrylonitrile resins, synthetic polymers such as polyvinylpyrrolidone, polyvinyloxazoline and polyvinylmorpholine, and natural organic compounds such as proteins and amino acids. In the present invention, as described in claim 1, the compound containing a nitrogen atom may be an adhesive polymer and / or a cation polymerizable compound.

Examples of the nitrogen atom-containing adhesive polymer include acrylonitrile, 2-dimethylaminoethyl (meth) acrylate, (meth) acrylamide, urethane (meth) acrylate, N-vinylpyrrolidone, N-vinyloxazoline, 2-vinyl Examples thereof include (meth) acrylic polymers or nitrile rubbers obtained by polymerizing or copolymerizing monomers such as pyridine, 4-vinylpyridine, and (meth) acryloylmorpholine.

Examples of the cationic polymerizable compound containing a nitrogen atom include a glycidylamine type epoxy resin, an acrylonitrile-butadiene rubber (CTBN) -modified epoxy having a terminal COOH group, an acrylonitrile-butadiene (ATBN) -modified epoxy having a terminal amine group, a crosslinked NBR-modified epoxy,
Examples include urethane-modified epoxy.

The atomic group containing a nitrogen atom is preferably -CN, -NRCO-, -NRCO-
O— is a functional group, wherein R is H or aliphatic,
Shows an alicyclic or aromatic hydrocarbon group. Examples of the compound having a functional group include a cyano compound, a nitrile compound, a polyurea, a polyamide, a polyurethane, a polyacrylonitrile, a polyvinylpyrrolidone, a copolymer thereof, and a natural organic compound such as a protein or an amino acid. These functional groups may be contained in an adhesive polymer or a cationically polymerizable compound.

In order to improve the tackiness of the curable adhesive composition of the present invention, a rosin resin, a modified rosin resin, a terpene resin, a terpene phenol resin, an aromatic modified terpene resin, a C5 or A tackifier resin such as a C9 petroleum resin or a coumarone resin may be added. Especially,
When the adherend is a polyolefin, a rosin-based resin and a petroleum resin are preferably used in that a strong adhesive force can be exhibited.

(Curing Adhesive Sheet) The curable adhesive sheet according to the present invention is obtained by processing the curable adhesive composition according to the present invention into a thin sheet by any method and forming a sheet. Can be The method of forming the sheet is not particularly limited, but preferably, the sheet is cured by a roll coating method, a gravure coating method, or an extrusion method on a release-treated sheet-like support. A method of processing the adhesive composition into a sheet is used. Even when the curable adhesive composition is solid or liquid, if the viscosity is high and it cannot be applied, it can be diluted with an appropriate solvent or melted by heating, thereby reducing the viscosity. May be.

The curable pressure-sensitive adhesive sheet obtained as described above exhibits pressure-sensitive adhesive properties at room temperature, and therefore, the surface having pressure-sensitive adhesive properties is protected with a release sheet for easy handling. Is preferred.

The curable pressure-sensitive adhesive sheet according to the present invention may be in the form of a double-sided pressure-sensitive adhesive tape having no substrate, or a substrate having a curable pressure-sensitive adhesive layer formed on one surface of the substrate. Alternatively, the base material may be formed into a sheet by forming a curable adhesive layer on both surfaces. The material constituting the base material is not particularly limited, but includes polyester, polyolefin, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyvinyl alcohol, cellophane, tri (di) acetyl cellulose, and cellulose. , A suitable plastic such as polycarbonate, polymethyl methacrylate, polyamide, and polyimide, a film made of a natural polymer, a nonwoven fabric, a woven fabric, a knitted fabric, a paper, and a metal foil.

If necessary, a substrate obtained by compounding these materials may be used. Further, the base material may be subjected to various surface treatments such as vapor deposition, corona treatment, flame treatment, antistatic treatment, easy adhesion treatment, primer coating, and peeling treatment.

The curable pressure-sensitive adhesive sheet according to the present invention is preferably wound in a roll shape, whereby the sticking workability can be improved. Of course, it may be formed in a sheet shape or a punched shape.

In the case of a curable adhesive sheet having no base material, it may be prepared in a form laminated on an appropriate plate-like member. Examples of such plate-like members include phenolic resin, epoxy resin, acrylic resin, urea resin, polyester, olefin resin, styrene resin, silicone resin, fluororesin and other appropriate synthetic resins, paper, cloth, nonwoven fabric, wood , Natural polymer-based materials such as rubber, inorganic materials such as glass, metal, ceramics, and composite materials thereof. A double-sided adhesive-type curable adhesive sheet can be prepared in a form in which a curable adhesive layer is laminated on a plate-like member made of these materials. When laminating, the curable adhesive composition may be applied onto the plate-like member and laminated, or the curable adhesive layer may be formed on the substrate treated by the release treatment method described above. After molding, it may be transferred to a plate-like member.

When the curable adhesive sheet laminated on the plate member is used, it can be applied to an adherend by a transfer method. Although the thickness of the curable pressure-sensitive adhesive sheet is not particularly limited, it is preferably in the range of 10 μm to 3 mm, more preferably 10 μm to 1 mm. 10
If it is thinner than μm, pressure-sensitive adhesiveness due to unevenness of the adherend surface,
As a result, the adhesive strength may be affected, and if it is thicker than 3 mm, the cured state may vary in the thickness direction.

(Function) The curable pressure-sensitive adhesive composition according to the first or second aspect of the present invention exhibits pressure-sensitive adhesive properties at an ordinary temperature in an initial state due to the function of the adhesive polymer. Therefore, the adherends can be bonded with a low pressure. The irradiation of light activates the cationic photopolymerization initiator, generates cations, and cationically polymerizes the cationically polymerizable compound with the cations, whereby the curing reaction proceeds. However, since the ratio of the molar equivalent of the nitrogen atom to the molar equivalent of the cation generated from the photocationic polymerization initiator when irradiated with light is 1 or more, the generated cation is an atomic group containing a nitrogen atom. Trapped in Therefore, the cation and the cationically polymerizable compound stably coexist in the curable adhesive composition. Therefore, since the curing reaction does not proceed immediately, pressure-sensitive adhesiveness is maintained at room temperature for a very long period. Therefore, even when light is irradiated in advance during manufacturing, the adherends can be easily attached to each other on the user side by utilizing the pressure-sensitive adhesiveness. That is, since the compound contains the nitrogen atom-containing compound, the pot life is remarkably prolonged, and the storage stability is remarkably improved.

On the other hand, when using a curable adhesive composition which has been previously irradiated with light, if it is heated after application, the cations trapped in the atomic group containing a nitrogen atom are released, and cationic polymerization is initiated. It proceeds in a very short time. Therefore, finally, the adherends are firmly joined to each other.

According to the third aspect of the present invention, the first aspect is provided.
Or, since the curable adhesive sheet is constituted by the curable adhesive composition according to the invention described in 2, even if light is previously irradiated during the production, the cation is formed by the atomic group containing a nitrogen atom. Are trapped, and the adherends can be easily bonded to each other using the pressure-sensitive adhesiveness. In addition, the trapping action by atomic groups including nitrogen atoms decreases or disappears due to heating,
The cation is released. Therefore, after the heating, the cationic polymerization proceeds immediately, and the adherends are firmly joined.

In the third aspect of the present invention,
The light does not need to be irradiated in advance, and may be irradiated when used. However, preferably, if the light is irradiated prior to the application as described in claim 4, no equipment for irradiating the light at the bonding site is required.

According to the fifth aspect of the present invention, when the adherends are bonded to each other using the curable pressure-sensitive adhesive sheet according to the third or fourth aspect, they are heated at the time of application or after application. The cation is released from being trapped by the atomic group containing a nitrogen atom, and the cationic polymerization proceeds immediately. Therefore, the adherends are firmly joined.

[0072]

The present invention will be more specifically described below with reference to non-limiting examples.

A: Adhesive polymer An adhesive polymer shown in Table 1 below was polymerized in the following manner. First, 120 parts by weight of ethyl acetate and 0.01 part by weight of dodecyl mercaptan are blended in a separable flask with respect to 100 parts by weight of the monomer composition shown in A of Table 1,
The mixture was uniformly stirred to obtain a monomer solution. This monomer solution was subjected to nitrogen bubbling, and the dissolved oxygen was sufficiently replaced with nitrogen. Thereafter, the above monomer solution was heated to 80 ° C., and then 0.03 parts by weight of azobisisobutyronitrile was added, and radical polymerization was carried out at the boiling point for 6 hours to obtain a tacky polymer.

B: Cationic polymerizable compound As the cationic polymerizable compound, a bisphenol A type epoxy resin and a urethane modified epoxy resin are prepared.
As shown in Table 1 below, they were used in Examples and Comparative Examples, respectively. The bisphenol A type epoxy resin was manufactured by Yuka Shell Epoxy Co., Ltd., trade name: Epicoat # 8
28 (epoxy equivalent 10.0) was used. The urethane-modified epoxy resin was adjusted as follows.

First, as a urethane prepolymer, hexamethylene diisocyanate (molecular weight = 168, manufactured by Nippon Polyurethane Co., trade name: Coronate HL) and 1,6
-Hexanediol (molecular weight = 118) was weighed at a molar ratio of 2: 1 and 100 parts by weight of these were dissolved in 100 parts by weight of methyl ethyl ketone and reacted at 80 ° C. for 4 hours to obtain the following formula (1) A) urethane prepolymer having the structure of (1) was obtained.

[0076]

Embedded image

Next, 2 mol of glycidol was added dropwise to 1 mol of the urethane prepolymer and reacted to obtain a urethane-modified epoxy resin represented by the following formula (2).

[0078]

Embedded image

The urethane-modified epoxy has a molecular weight of 602.

C: Photocationic polymerization initiator As shown in Table 1 below, a commercially available photocationic polymerization initiator, manufactured by Asahi Denka Co., Ltd., trade name: Adeka Optomer SP170
(Molecular weight = 1270).

(Preparation of Curable Adhesive) A: adhesive polymer, B: cationic polymerizable compound, and C: cationic photopolymerization initiator prepared as described above were mixed at the ratio shown in Table 1. By diluting with ethyl acetate so as to have a solid content of 40% by weight, a curable adhesive composition was obtained.

Table 1 shows the composition of each curable adhesive composition, the molar equivalent of nitrogen atom, the molar equivalent of cation (H ⁺ ) generated upon irradiation with light, and the molar equivalent ratio (N / H). ⁺ ),
Epoxy equivalent of cationic polymerizable compound and cation (H
⁺ ) Shows the mole (%) based on the cationically polymerizable compound.

(Evaluation) Initial adhesive strength The initial adhesive strength was measured at room temperature and under heating, respectively.
It was measured in the following manner.

A) At room temperature: The above curable pressure-sensitive adhesive composition was applied to a corona-treated surface of a 50 μm-thick polyethylene terephthalate (PET) film having a corona-treated surface to a final thickness of 100 μm using a roll coater. The resultant was applied and dried to obtain a first adhesive sheet sample for evaluating adhesive strength.

Similarly, a curable adhesive composition was applied and dried on the release-treated surface of a 50 μm-thick PET film whose surface had been release-treated, and a second adhesive for measuring ethyl acetate insoluble content was obtained. Was obtained. The first and second pressure-sensitive adhesive sheet samples were cut to a width of 10 mm to obtain first and second test pieces, respectively.

Using an ultra-high pressure mercury lamp on the surface of the adhesive layer of the above two test specimens, ultraviolet rays having a center wavelength of 365 nm were irradiated at 5 J / cm 2.
Irradiation was performed so as to obtain cm ² . The first specimen is JIS
Using a laminator at 23 ° C. according to Z-0237,
Lamination pressure 3kg / cm, lamination speed 1m / min,
At a laminating temperature of 23 ° C, it is stuck on a stainless steel plate,
After leaving for 30 minutes after bonding, the peeling speed is 50 mm /
In 180 minutes, the 180 ° peel adhesion was measured.

From the second specimen, about 0.2 mg of the adhesive was weighed into a sample tube, 40 ml of ethyl acetate was added thereto, and the mixture was shaken at 23 ° C. for 24 hours to obtain an ethyl acetate insoluble matter (weight %) Was measured.

B) Heating: First and second test specimens were prepared in the same manner as in the case of a), and were irradiated with an ultraviolet ray having a center wavelength of 365 nm at 5 J / cm ² using an extra-high pressure mercury lamp. After irradiation, the first specimen is irradiated within 1 minute after light irradiation, a)
The lamination pressure was 3 kg / cm and the laminating speed was 1 m /
After laminating at 100 ° C. for 10 minutes, lamination is performed in the same manner as in a).
The 0 ° peel adhesion was measured.

Further, the second specimen was heated to a temperature of 100 ° C. for 10 minutes, about 0.2 mg of the adhesive was weighed into a sample tube, 40 ml of ethyl acetate was added, and
After shaking at 3 ° C., the ethyl acetate insoluble content was measured.

Adhesive Strength One Hour After Light Irradiation Each adhesive strength at room temperature and under heating was evaluated in the same manner as described above, except that the measurement was performed after the ultraviolet irradiation was left at a temperature of 23 ° C. for one hour. .

Adhesion Force One Week After Light Irradiation The 180 ° peel adhesion at room temperature and under heating was measured in the same manner as described above, except that the adhesion was measured after standing for one week at a temperature of 23 ° C. after irradiation with ultraviolet light. evaluated.

Adhesion force after 1 month of light irradiation 180 ° peel adhesion at room temperature and under heating was measured in the same manner as in Example 1 except that the measurement was carried out after standing at 23 ° C. for 1 month after irradiation with ultraviolet light. did.

The results are shown in Table 2 below.

[0094]

[Table 1]

[0095]

[Table 2]

In Comparative Example 2, since only an adhesive polymer was used, no ethyl acetate-insoluble content was generated, but only pressure-sensitive adhesiveness was exhibited. As shown, the adhesive strength did not increase even after being left for a predetermined time after light irradiation.

In Comparative Example 1, even in the case of laminating at room temperature, ethyl acetate insolubles were generated in a short time after light irradiation, the tackiness was lost, and lamination could not be performed (
(See lamination under heating and evaluation results of). This is presumably because the generated cation immediately promoted the polymerization of the cationically polymerizable compound, and the curing proceeded, and the tack disappeared.

On the other hand, in Examples 1 to 3, even if the cations generated by light irradiation were trapped by the atomic group containing a nitrogen atom and left for one month after the light irradiation, they remained at room temperature. Ethyl acetate insolubles were not generated, sufficient pressure-sensitive adhesiveness was exhibited, and lamination was possible. In addition, when heated, in each case, a sufficient adhesive strength was finally exhibited. This is presumably because the laminate was instantaneously cured by lamination under heating at 100 ° C., and the adhesive strength was increased.

Accordingly, it can be seen that a sufficient adhesive force can be obtained in a very short time, and the bonding step can be greatly simplified and efficiency can be improved. In addition, since ethyl acetate-insoluble components are not generated at room temperature as described above, it is understood that light irradiation does not have to be performed at the time of bonding at the bonding site if light irradiation is performed in advance at the time of production.

[0100]

In the curable adhesive composition according to the first and second aspects of the present invention, the pressure-sensitive adhesive polymer exhibits sufficient pressure-sensitive adhesiveness in the initial state at normal temperature.
In particular, since the ratio between the molar equivalent of the nitrogen atom and the molar equivalent of the cation generated from the photocationic polymerization initiator when irradiated with light is set to 1 or more, even when the light was previously irradiated, the light was generated. Since the cation is trapped in the atomic group containing a nitrogen atom, the cationic polymerization does not proceed, and the cation coexists stably with the cationically polymerizable compound. Therefore,
Even when irradiated with light, the pressure-sensitive adhesive property of the tacky polymer is not lost.

Therefore, for example, by irradiating light beforehand at the time of manufacturing, it is possible to omit the irradiation of light at the bonding site. Therefore, at the bonding site,
There is no need to prepare a device for irradiating light, and there is no need to perform a complicated light irradiation operation. In addition, it can be suitably used for an adhesive portion where light irradiation is difficult.

Further, when heated, the cations are released from the trapped state, and the cationically polymerizable compound immediately starts cationic polymerization and rapidly cures. Therefore, ultimately, a sufficient adhesive strength equivalent to that of the adhesive is exhibited.

Therefore, in the initial state, the adherends can be easily adhered to each other by utilizing the pressure-sensitive adhesiveness in the same manner as in the case of the conventional pressure-sensitive adhesive. In addition, it is possible to provide a curable adhesive composition excellent in operability, which does not require a complicated operation for curing at the bonding site. In addition, heating for releasing the cations from the trapped state does not need to be performed at a very high temperature, and therefore can be applied to an adherend having insufficient heat resistance.

According to the third aspect of the present invention, since the curable adhesive sheet is constituted by the curable adhesive composition according to the present invention, the cured adhesive sheet is initially at room temperature with respect to the adherend. It can be easily attached. In addition, by heating after the light irradiation, sufficient adhesive strength similar to that of the adhesive is exhibited in the same manner as described above, and the adherends can be firmly joined to each other.

Further, as in the invention according to claim 4, in the curable adhesive sheet according to the present invention, even when light is irradiated prior to sticking, an atomic group containing a nitrogen atom is used. Cations are trapped and pressure sensitive adhesion is not lost. Therefore, even after long-term storage, the adherends can be easily bonded to each other using the curable adhesive sheet. Also in this case, the cations are released from the trapped state by heating, the polymerization of the cationically polymerizable compound proceeds rapidly, and finally, the adherends are firmly joined to each other.

In the bonding method according to the fifth aspect of the present invention, when the adherends are bonded to each other using the curable pressure-sensitive adhesive sheet according to the third or fourth aspect, heating is performed during or after the bonding. The cations trapped by the heating are released, and the polymerization of the cationically polymerizable compound proceeds rapidly. Therefore, the adherends are firmly joined.

Claims (5)

[Claims] An adhesive polymer, a cationically polymerizable compound, and a cationic photopolymerization initiator, and at least one of the adhesive polymer and the cationically polymerizable compound has a nitrogen atom in a molecule. The ratio of the molar equivalent of the nitrogen atom to the molar equivalent of the cation generated from the photocationic polymerization initiator when irradiated with light is 1
As described above, a curable adhesive composition containing a nitrogen atom. 2. An adhesive polymer, a cationically polymerizable compound, a compound having a nitrogen atom in a molecule, and a photo-cationic polymerization initiator, wherein a molar equivalent of the nitrogen atom and light upon irradiation with light are obtained. The ratio to the molar equivalent of the cation generated from the cationic polymerization initiator is 1
As described above, a curable adhesive composition containing a nitrogen atom. 3. A curable pressure-sensitive adhesive sheet comprising the curable pressure-sensitive adhesive composition according to claim 1 or 2. 4. The curable pressure-sensitive adhesive sheet according to claim 3, wherein light is irradiated prior to sticking. 5. A bonding method, wherein when the adherends are bonded to each other using the curable pressure-sensitive adhesive sheet according to claim 3 or 4, heat is applied during or after the bonding.