JPH10219200A - Curable pressure-sensitive adhesive sheet and method for joining member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a pressure-sensitive adhesive sheet which has sufficient initial tank in a normal state, can be easily cured by irradiation with light, does not need severe conditions, such as high-temperature and high-pressure pressing, in sticking, by blending a pressure-sensitive adhesive polymer, an epoxy compound, a vinyl ether compound and a photoinduced cationic polymerization initiator. SOLUTION: A pressure-sensitive adhesive polymer, preferably comprising an acrylic polymer, is blended with an epoxy compound, a vinyl ether compound and a photoinduced cationic polymerization initiator, preferably comprising a photosensitive onium salt compound. The amounts of the epoxy compound, vinyl ether compound and photoinduced cationic polymerization initiator respectively blended are preferably 30-70 pts.wt., 1-30 pts.wt. and 0.01-10 pts.wt. The joining of a member by using this pressure-sensitive adhesive sheet is performed by irradiating the sheet with light to cure it before or after joining the member to an adherent through the sheet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of joining a curable pressure-sensitive adhesive sheet and a member which has tackiness in a normal state and can be cured after application, and more particularly, to a method for joining a sheet at the time of attachment or at the beginning of joining. Has adhesive strength and cohesive strength that can be temporarily fixed,
The present invention relates to a curable adhesive sheet which is adhesively cured by light irradiation and a method for joining members using the curable adhesive sheet.

[0002]

2. Description of the Related Art Acrylic pressure-sensitive adhesives have heat resistance, weather resistance,
Because of its excellent oil resistance, it is widely used for various adhesive processed products such as adhesive tape. However, an acrylic pressure-sensitive adhesive is designed to have a low elastic modulus as a physical property in order to develop a pressure-sensitive adhesive force. Therefore, it is difficult to develop high bonding strength such as adhesives, and it is used for applications that require high bonding strength, such as bonding steel plates for vehicles, structural members for houses and buildings, and housing members. Could not.

Therefore, a pressure-sensitive adhesive has been proposed which has both easy workability and bonding strength and film strength as hard as an adhesive, and which is excellent in safety because it contains no volatile components. For example, JP-A-2-272076 discloses that
An adhesive tape using a pressure-sensitive thermosetting adhesive composed of a photopolymerizable composition containing an acrylate monomer and an epoxy resin is disclosed. Here, it is stated that only the acrylate monomer in the photopolymerizable composition is polymerized to form an adhesive tape, and the epoxy resin is cured by heating after application, thereby increasing the adhesive strength.

However, in the method described in JP-A-2-272076, since heat is used for curing the epoxy resin, a material having poor heat resistance cannot be used as the adherend. However, there is a problem that the material is limited.

On the other hand, JP-A-5-506465 discloses a photosensitive composition comprising a photoradical polymerization component such as an acrylate monomer, a photocationic polymerization component such as an epoxy compound, and an organometallic complex polymerization initiator. A pressure-sensitive adhesive is disclosed. This pressure-sensitive adhesive has been proposed in order to increase the adhesive force, and in the production stage of the pressure-sensitive adhesive, both photoradical polymerization and photocation polymerization proceed, and these polymerization reactions are carried out. This is completed when the pressure-sensitive adhesive is formed into a sheet or the like. That is,
The obtained pressure-sensitive adhesive sheet is configured to have sufficient strength in advance. Therefore, when bonding to an adherend, a sufficient adhesive strength can be expected, but even when an external stimulus such as heat or light is applied, no further improvement in the adhesive strength can be expected.

Epoxy resin adhesives have excellent creep resistance, light resistance, water resistance, heat resistance, chemical resistance, etc., high adhesive strength, and a wide range of metals, plastics, glass and the like. Since various materials can be adhered, it is widely used for attaching various joining members.

However, the epoxy resin adhesive is
Since it is generally used in the form of a liquid, there are problems that coating unevenness occurs at the time of coating, the appearance of the joint end face is impaired due to spotting due to excessive coating, and it is not possible to apply the coating once again to the surface once applied. Was. Further, the epoxy resin-based adhesive is mainly configured as a two-part adhesive, and since the mixing ratio between the main agent and the curing agent is limited, attention must be paid to the mixing ratio when used.
In some cases, the desired adhesive strength could not be achieved due to an incorrect mixing ratio.

Therefore, a sheet-like epoxy adhesive formed by molding an epoxy resin-based adhesive into a sheet or film has been proposed (Japanese Patent Application Laid-Open No. 60-173076). However, the sheet-like epoxy adhesive has a high elastic modulus in a normal state and a low initial tackiness. Therefore, there is a problem that the sheet-like epoxy adhesive does not have a temporary fixing property and the workability at the time of joining is not sufficient. In addition, since the adhesiveness to the adherend is not sufficient, the adhesive must be adhered to the adherend under severe conditions such as high temperature and high pressure press, and the adherence does not have resistance to such processing conditions. Could not be applied to kimono.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a material which has a sufficient initial adhesive strength under normal conditions, can be easily cured by irradiating light, and has an insufficient heat resistance. An object of the present invention is to provide a method of joining a curable pressure-sensitive adhesive sheet and a member which can be suitably used and does not require severe conditions such as high temperature and high pressure pressing at the time of sticking.

[0010]

Means for Solving the Problems Although not yet known, the inventors of the present invention have previously made it possible to use such members for joining members having insufficient heat resistance and to apply severe bonding conditions such as a high-temperature / high-pressure press. As a curable adhesive sheet that can be used without the need for a curable adhesive sheet containing an acrylic polymer, a compound having an epoxy group, and a compound that is irradiated with light to induce ring opening of the epoxy group. Suggested. In this curable pressure-sensitive adhesive sheet, the compound having an epoxy group is cured by light irradiation. Therefore, before or after the curable pressure-sensitive adhesive sheet is adhered to the adherend, the curable pressure-sensitive adhesive sheet is simply irradiated with light. The curable adhesive sheet can be firmly joined to the adherend, and the heat resistance of the adherend does not matter. In addition, the acrylic polymer has sufficient initial adhesive strength,
Adhesion when applied to an adherend is also enhanced.

However, when light is applied to the curable pressure-sensitive adhesive sheet, the curing reaction proceeds simultaneously with the light irradiation, and the elasticity of the curable pressure-sensitive adhesive sheet increases in a relatively short time. In some cases, the adhesiveness to the toner was reduced. Therefore, if the adherends are not joined to each other using the curable adhesive sheet immediately after the light irradiation, sufficient adhesive strength may not be obtained.

The present invention has been made to further solve the above-mentioned problems.
A curable adhesive sheet comprising an adhesive polymer, a compound having an epoxy group, a vinyl ether compound, and a cationic photopolymerization initiator.

The invention according to claim 2 is characterized in that the adhesive polymer is an acrylic polymer and the photocationic polymerization initiator is a photosensitive onium salt compound.

According to a third aspect of the present invention, when the joining members are bonded to each other via the curable adhesive sheet according to the first or second aspect, light is applied to the curable adhesive sheet. It is a joining method of a characteristic member.

Hereinafter, the present invention will be described in detail. Adhesive polymer The adhesive polymer used in the curable adhesive sheet according to the present invention is blended so that the adhesive sheet has tackiness in a normal state. Is not particularly limited as long as it can provide tackiness. Materials that can be used as the adhesive polymer include, for example, acrylic polymers, polyesters, polyurethanes, silicones, polyethers, polycarbonates, polyvinyl ethers, polyvinyl chlorides,
Examples thereof include polyvinyl acetate and polyisobutylene, and copolymers based on these can also be used.

Regarding the molecular weight of the above-mentioned adhesive polymer,
Although not particularly limited, the molecular weight is preferably large, and the weight average molecular weight is preferably about 200,000 to 5,000,000. When the weight average molecular weight is less than 200,000,
The cohesive force of the curable pressure-sensitive adhesive sheet is insufficient, stringing may occur at the time of application and peeling, and the weight average molecular weight may be 500.
If it exceeds 10,000, the viscosity of the composition containing the adhesive polymer and the compound having an epoxy group becomes too high to form a sheet in some cases.

Regarding the structure of the adhesive polymer, for example, a homopolymer structure, a random copolymer structure, a block copolymer structure, an alternating copolymer structure, a stereoregular structure,
The structure is arbitrary, such as a multibranched structure, a star-shaped structure, a dendritic structure, a ladder structure, a cyclic structure, and a helical structure, and is not particularly limited.

[0018] Among the above-mentioned adhesive polymers, they are commonly used as a main component of the adhesive in order to exhibit excellent initial adhesive strength, and the control of the adhesive properties is easy. It is preferable to use an acrylic polymer.

The structure of the acrylic polymer is not particularly limited, and various structures exemplified for the adhesive polymer described above can be used. More preferable examples of the acrylic polymer include a copolymer obtained by copolymerizing a compound having a (meth) acryloyl group with a copolymerizable monomer copolymerizable with the compound.

Examples of the compound having a (meth) acryloyl group include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, tert-butyl (meth) acrylate,
Ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, isomiristyl (meth) acrylate, isobornyl (meth) acrylate, benzyl (meth) acrylate Glycidyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, and the like.

The copolymerizable monomer is not particularly limited as long as it is a compound having an unsaturated bond copolymerizable with the compound having a (meth) acryloyl group, but the epoxy group contained in the curable adhesive sheet is not particularly limited. Is preferable because a vinyl monomer which is non-reactive can enhance the storage stability of the curable adhesive sheet.

From the above viewpoint, it is not preferable to use a vinyl monomer having a carboxyl group such as acrylic acid or methacrylic acid or a vinyl monomer such as maleic anhydride having an acid anhydride skeleton.

Examples of the above vinyl monomer include (meth) acrylonitrile, N-vinylpyrrolidone, N-acryloylmorpholine, N-vinylcaprolactone,
N-vinylpiperidine, styrene, indene, α-methylstyrene, p-methylstyrene, p-chlorostyrene, p-chloromethylstyrene, p-methoxystyrene, p-tert-butoxystyrene, divinylbenzene, vinyl acetate, propionic acid Vinyl, vinyl butyrate, vinyl caproate, vinyl benzoate, vinyl cinnamate and the like can be mentioned.

More preferably, as the adhesive polymer, an acrylic polymer obtained by subjecting a photopolymerizable composition containing an acrylic monomer to photoradical polymerization is used. In this case, an acrylic polymer is obtained by photoradical polymerization by irradiating the photopolymerizable composition with light. Therefore, along with a resin having an epoxy group, a vinyl ether compound and a photocationic polymerization initiator, if the acrylic monomer and the photoradical polymerization initiator are contained in the photopolymerizable composition, by irradiating light, The curable adhesive sheet according to the present invention can be easily obtained.

Compound Having Epoxy Group The compound having an epoxy group used in the curable adhesive sheet of the present invention is opened by the action of a compound which induces a ring-opening reaction of the epoxy group when irradiated with light. It is used to cure the curable adhesive sheet by ring polymerization.

As the compound having an epoxy group,
There is no particular limitation as long as it contains an epoxy group.
For example, epoxy resins such as bisphenol A epoxy resin, bisphenol F epoxy resin, novolak type epoxy resin and alicyclic aliphatic epoxy resin, and glycidyl amine compounds such as glycidyl ester compounds are exemplified.

Vinyl ether compound Examples of the vinyl ether compound include n-propyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, tert-butyl vinyl ether, tert-amyl vinyl ether, cyclohexyl vinyl ether, 2-ethylhexyl vinyl ether,
Dodecyl vinyl ether, octadecyl vinyl ether, 2-chloroethyl vinyl ether, ethylene glycol butyl vinyl ether, triethylene glycol methyl vinyl ether, (4-vinyloxy) butyl benzoate, ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, tetraethylene glycol Divinyl ether, butane-1,4-diol-divinyl ether, hexane-1,6-diol-divinyl ether,
Cyclohexane-1,4-dimethanol-divinyl ether, di (4-vinyloxy) butyl isophthalate, di (4-vinyloxy) butyl glutarate, di (4-vinyl succinate)
Vinyloxy) butyl trimethylolpropane trivinyl ether, 2-hydroxyethyl vinyl ether, 4-
Hydroxybutyl vinyl ether, 6-hydroxyhexyl vinyl ether, cyclohexane-1,4-dimethanol-monovinyl ether, diethylene glycol monovinyl ether, 3-aminopropyl vinyl ether, 2- (N, N-diethylamino) ethyl vinyl ether, urethane vinyl ether, polyester vinyl ether, etc. Although it can be mentioned, it is not particularly limited.

Photo-Cationic Polymerization Initiator In the curable adhesive sheet of the present invention, the above-mentioned photo-cationic polymerization initiator is used in order to promote the curing by ring-opening polymerization of the epoxy group by light irradiation.

The cationic photopolymerization initiator is not particularly limited as long as the epoxy group can be subjected to ring-opening polymerization by irradiation with light. For example, photosensitive onium salts and organometallic complexes can be used. .

Preferably, a photosensitive onium salt compound is used as the cationic photopolymerization initiator. That is, as the light irradiated to advance the curing reaction, ultraviolet light having a high energy intensity and a wavelength of 300 nm or more, which promptly advances ring opening of the epoxy group, is preferably used. The above-mentioned photosensitive onium salt compound is suitably used as the compound activated by the irradiation of the above.

For example, when an adhesive polymer such as an acrylic polymer is formed by photoradical polymerization by irradiating a photopolymerizable composition with light, as described above,
Light having a wavelength of 360 nm or more is used. In this case, the light irradiated for curing at the time of using the curable adhesive sheet needs to have a wavelength of less than 360 nm, but the photosensitive onium salt compound has a wavelength of less than 360 nm. It can be suitably used because it is activated by irradiation.

Further, since the onium salt compound is stable against heat, it is advantageous in improving the storage stability of the curable pressure-sensitive adhesive sheet before light irradiation, and the structure at the growth end is at room temperature. The curing reaction after irradiation with light and after lamination can surely proceed at room temperature because the reaction is so active as to react and there is no deactivation as a termination reaction.

Specific examples of the onium salt compound include aromatic diazonium salts, aromatic iodonium salts, aromatic sulfonium salts, and pyridinium salts. More specifically, for example, Optomer SP-
150 (manufactured by Asahi Denka Kogyo KK), Optmer SP-170
(Manufactured by Asahi Denka Kogyo), UVE-1014 (manufactured by General Electronics), CD-1012 (manufactured by Sartomer), Sun Aid SI-60L (manufactured by Sanshin Chemical Industry),
Sun-Aid SL-80L (manufactured by Sanshin Chemical Industry), Sun-Aid SI-100L (manufactured by Sanshin Chemical Industry), CI-20
64 (manufactured by Nippon Soda), CI-2639 (manufactured by Nippon Soda), CI-2624 (manufactured by Nippon Soda), CI-248
Commercially available compounds such as 1 (manufactured by Nippon Soda Co., Ltd.) can be used.

The lamp used for the light irradiation includes:
Any lamp can be used as long as it has an emission distribution of 800 nm or less, but when an acrylic polymer is obtained by the above-described photoradical polymerization, preferably, a wavelength of 360 nm is used.
m, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a chemical lamp, a black light lamp, a micro-wave excitation mercury lamp, a metal halide lamp, and the like can be used. In this case, in order to prevent curing of only the surface layer and realize internal curing, light having a wavelength of 320 nm or less may be cut and irradiated.

Blending Ratio In the curable pressure-sensitive adhesive sheet according to the present invention, the blending ratio of the above-mentioned compound having an epoxy group, the above-mentioned vinyl ether-based compound, and the cationic photopolymerization initiator is preferably such that the epoxy group is contained. 30 to 70 parts by weight of a compound to be used, 1 to 30 parts by weight of a vinyl ether compound, and 0.01 to 10 parts by weight of a cationic photopolymerization initiator.

When the compounding ratio of the epoxy group-containing compound is less than 30 parts by weight, even if the composition is cured, the original adhesive properties of the epoxy resin may not be exhibited. In some cases, the cohesive force of the sheet is reduced, and it is difficult to temporarily fix the sheet to an adherend, and improvement in workability may not be expected.

When the blending ratio of the vinyl ether compound is less than 1 part by weight, the curing is substantially the same as that of the compound having an epoxy group alone, and when it exceeds 30 parts by weight, the cured product obtained by photocuring is not cured. In some cases, the strength becomes low and sufficient adhesive strength cannot be exhibited.

When the compounding ratio of the cationic photopolymerization initiator is 0.0
If the amount is less than 1 part by weight, the concentration of the cationically polymerizable species will be low even if photocured, and the curing speed may not be able to be set to an appropriate size. The curing proceeds rapidly on the surface of the pressure-sensitive adhesive sheet, and even when the composition contains a vinyl ether compound, the adhesion of the surface of the curable pressure-sensitive adhesive sheet to the adherend may decrease. Therefore, even though the mechanical strength of the final cured adhesive product is sufficient, the adhesive strength may not be sufficient. In the above preferable mixing ratio, a more preferable mixing ratio of the cationic photopolymerization initiator is 0.05 to 5 parts by weight, and further preferably 0.1 to 3 parts by weight.

The acrylic polymer is used in an amount of 30 to 70 parts by weight based on 30 to 70 parts by weight of a compound having an epoxy group, 1 to 30 parts by weight of a vinyl ether compound and 0.01 to 10 parts by weight of a cationic photopolymerization initiator. It is preferable to mix them in parts by weight. When the blending ratio of the acrylic polymer is less than 30 parts by weight, the cohesive force of the curable adhesive sheet is reduced, so that the temporary fixing to the adherend becomes impossible, and the improvement of workability may not be expected. If the number is more than the number of parts, the original adhesiveness of the epoxy resin may not be expected.

Other additives In the curable adhesive sheet according to the present invention, if necessary, heat resistance and cohesive strength at a high temperature may be improved as long as the object of the present invention is not impaired. One or more crosslinkable monomers such as a functional acrylate monomer or a polyfunctional vinyl monomer may be contained.

The crosslinkable monomer is not particularly restricted but includes, for example, hexanediol di (meth) acrylate, ethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate. ) Acrylate,
Polypropylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, Examples thereof include dipentaerythritol hexa (meth) acrylate, epoxy acrylate, polyester acrylate, and urethane acrylate, and one or more of these are suitably used. In addition, "(meth) acrylate" in this specification means "acrylate" or "methacrylate."

Further, in the curable adhesive sheet according to the present invention, the adhesive polymer, the compound having an epoxy group,
In addition to the vinyl ether-based compound and the cationic photopolymerization initiator, known tackifying resins and extenders may be appropriately blended as long as the object of the present invention is not impaired.

For example, in order to improve the tackiness of the curable adhesive sheet 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 C9 series And a tackifier resin such as a petroleum resin and a chroman resin. Especially,
When the adherend is a polyolefin, a rosin-based resin and a petroleum resin are preferable in that a strong adhesive force can be exhibited.

For the purpose of improving coatability, thickeners such as acrylic rubber, epichlorohydrin rubber, isoprene rubber, and butyl rubber, thixotropic agents such as colloidal silica and polyvinylpyrrolidone, and increasing amounts of calcium carbonate, titanium oxide, clay and the like. An agent may be added.

Further, in order to impart high strength shear adhesive force when the adhesive sheet is used, inorganic hollow bodies such as glass balloons, alumina balloons and ceramic balloons; and organic hollow bodies such as nylon beads, acrylic beads and silicon beads. Spherical bodies; organic hollow bodies such as vinylidene chloride balloons and acrylic balloons; and single fibers such as glass, polyester, rayon, nylon and cellulose may be added.

When the above glass fiber is blended, it is possible to add a fibrous chip to the composition. High shear strength can be obtained.

Production of Curable Adhesive Sheet The method for producing the curable adhesive sheet according to the present invention is not particularly limited, and solvent coating, extrusion coating, calendering, UV polymerization and the like are preferably used. .

The solvent coating method comprises the steps of:
This is a method in which a compound having an epoxy group, a vinyl ether-based compound, and a cationic photopolymerization initiator are dissolved in an organic solvent, applied to a substrate, and dried to form a sheet. In addition, the extrusion coating method and the calendar method include a hot-melt adhesive polymer having a weight average molecular weight of about tens of thousands to 500,000, a compound having an epoxy group, a vinyl ether compound, and a cationic photopolymerization initiator. This is a method in which the composition is heated and melted, and the composition is coated on a substrate using a melt coating apparatus.

As a preferred embodiment of the method for producing a curable adhesive sheet according to the present invention, an example using the above-mentioned UV polymerization method will be described. In this preferred embodiment, a photopolymerization comprising a (meth) acrylate monomer, a photo-radical polymerization initiator sensitive to a wavelength region different from that of the photosensitive onium salt compound, a compound having an epoxy group, a vinyl ether compound and a photosensitive onium salt compound An acidic composition is used. This photopolymerizable composition is applied to an appropriate sheet substrate, only the photoradical polymerization initiator is exposed, only radical polymerization is caused to form an acrylic polymer as an adhesive polymer in the sheet, and the curable composition is cured. An adhesive sheet can be obtained. In the production method using the photopolymerizable composition, an acrylic polymer as an adhesive polymer can be polymerized by light irradiation.

In the above preferred embodiment, more preferably, the photosensitive onium salt compound is hardly exposed to light in a wavelength region of 360 nm or more, and the photo radical polymerization initiator is preferably
The photosensitive onium salt compound and the photo-radical polymerization initiator are selected so as to be sensitive to light in a wavelength region of 60 nm or more and less than 800 nm, whereby 360 nm to 800 nm
By irradiating light in the wavelength region of nm, a curable adhesive sheet can be obtained.

The wavelength of the light to be irradiated at the time of manufacture is 800 n
In the case of m or more, the heat due to the radiant heat deteriorates the performance of the curable adhesive sheet, so that equipment such as a heat ray cut filter or other heat removal equipment is required. On the other hand, as described above, when a photo-radical polymerization initiator activated by light in a wavelength region of less than 800 nm is used,
There is no need to provide such equipment.

When light of less than 360 nm is irradiated,
Since the photosensitive onium salt compound is activated, the curable adhesive sheet according to the present invention cannot be obtained. Therefore, as described above, preferably, it is 360 nm or more and 80 nm or more.
A photo-radical polymerization initiator sensitive to a wavelength region of less than 0 nm is used.

As described above, by setting the boundary of the photosensitive wavelength between the photosensitive onium salt compound and the photo-radical polymerization initiator to 360 nm, various light sources can be easily used according to the light emission spectrum pattern of the light source lamp. 3
Light in a wavelength region of 60 nm or more and light in a wavelength region of less than 360 nm can be selectively used.

In order to induce a reaction for opening the epoxy group, a larger energy is required than in the case of the photoradical polymerization. Therefore, more preferably, at the time of the photoradical polymerization, when photoradical polymerization is performed by irradiating light in a wavelength region of 360 nm or more to initiate photocationic polymerization and induce a ring opening reaction of an epoxy group,
It is desirable to use light having a wavelength of less than 360 nm.

The photo-radical polymerization initiator activated by light in the wavelength region of 360 nm or more includes 360 n
Compounds that must be activated by light having a wavelength of at least m and that do not cause energy transfer to the photocationic polymerization initiator with light of less than 360 nm are preferred.
Preferred examples of such a photoradical polymerization initiator include, for example, 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone, α-hydroxy-α, α′-dimethylacetophenone, methoxyacetophenone Acetophenone derivative compounds such as 2,2-dimethoxy-2-phenylacetophenone; benzoin ether compounds such as benzoin ethyl ether and benzoin propyl ether; ketal derivative compounds such as benzyl dimethyl ketal; halogenated ketones;
Acylphosphine oxide; acylphosphonate; bis- (2,6-dimethoxybenzoyl) -2,
4,4-trimethylpentylphosphine oxide and the like can be mentioned.

Among the above examples of the photopolymerization initiator, in particular, 3
Acylphosphine oxide, acylphosphonate, bis- (2,6-dimethoxybenzoyl) -2, which has a high absorption coefficient for light in a wavelength region exceeding 60 nm.
4,4-Trimethylpentylphosphine oxide is preferred.

Examples of lamps used for light irradiation in the photoradical polymerization include low-pressure mercury lamps, medium-pressure mercury lamps,
A high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a chemical lamp, a black light lamp, a microwave excitation mercury lamp, a metal halide lamp, and the like can be used.

Adhesive Member The curable adhesive sheet according to the present invention is used as it is in the form of a double-sided pressure-sensitive adhesive tape so as to be interposed between bonding members when they are bonded to an adherend. Alternatively, the adhesive may be formed as an adhesive layer on at least one surface of a substrate and configured as an adhesive member with the substrate.

Examples of the substrate include various nonwoven fabrics such as rayon or cellulose, films or sheets made of various synthetic resins such as polyethylene, polyester, cellophane, polypropylene, polystyrene, and polyimide; foamed polyethylene, urethane foam, and neoprene foam. , Foamed vinyl chloride, foamed polystyrene and other foams, polystyrene, ABS, acrylic, polypropylene, polyethylene and other synthetic resins, resin plates,
Sheets or plates made of various metals such as steel, stainless steel, copper, and aluminum, glass, wood, paper, cloth, tiles, gypsum boards, light culverts, and the like can be used without any particular limitation. Further, the shape of the substrate is not limited to a thin shape such as a sheet or a plate, and may be any shape such as a prism, a rod, a sphere, and a shape having an aspheric surface.

[0060] In the bonding method method of joining members according to the invention of claim 3 of the member, bonding the joining member to the adherend with the adhesive and pressure-sensitive adhesive sheet according to claim 1 or 2 described above At the time, that is, before bonding or by irradiating light after bonding,
The curable adhesive sheet is cured. In this case, "before bonding" preferably means before bonding and before curing of the resin having an epoxy group is completed by light irradiation. When the activation energy is applied and the curing of the compound having an epoxy group is completed, the curable pressure-sensitive adhesive sheet becomes too hard, and a sufficient initial adhesive strength may not be obtained.

When the curing member is irradiated with light before the joining member is joined to the adherend and the curing of the curable adhesive sheet is advanced, the joining member and the adherend are not irradiated with light. Further, it is possible to prevent the deterioration of the joining member and the adherend due to light. Therefore, when joining an adherend or a joining member that is likely to be deteriorated by light irradiation, it is desirable to irradiate the curable adhesive sheet in advance with light as described above. Further, when one of the adherend and the bonding member is easily deteriorated by light and the other is hardly deteriorated by light, the light is irradiated by bonding a curable adhesive sheet to the other member side, Thereafter, it may be bonded to the one member.

Regarding the wavelength of the light irradiated upon curing, when the above-mentioned photosensitive onium salt compound is used as the photocationic polymerization initiator, the light is in the wavelength region of 300 nm or more, and the intensity is 1 mW / cm ^2. ~ 100mW / cm
It is preferred to use less than ^two lights. Wavelength is 300nm
If less than the above, sufficient energy to activate the photosensitive onium salt compound can be obtained, but there is not much light transmission power, only the adhesive surface is cured, and the bonding surface of the curable adhesive sheet is cured. Adhesion to the adherend may be reduced. Further, the inside of the curable adhesive sheet may remain uncured.

The intensity of light in the wavelength region of 300 nm or more is
In the case of less than 1 mW / cm ² , the energy is not enough to activate the photosensitive onium salt compound, and only a small amount of the onium salt compound is exposed to light, so that the curing speed becomes extremely slow. Therefore, preferably, 300 nm or more, more preferably 300 nm or more, less than 800 nm,
More preferably, light in a wavelength region of 300 nm or more and less than 400 nm is used.

When the intensity of the light irradiated during the above-mentioned curing exceeds 100 mW / cm ² , the radiation heat due to the light cannot be ignored, the curing reaction due to the heat is accelerated, and the bonding members must be bonded immediately after the light irradiation. , Immediately surface hardening occurs. That is, the adhesiveness of the curable adhesive sheet to the adherend may hardly be seen.

[0065] In adhesive and pressure-sensitive adhesive sheet according to the invention described in the action claim 1,
Since the adhesive polymer has adhesiveness in a normal state, it can be adhered to an adherend. In addition, since it contains a compound having an epoxy group, a vinyl ether-based compound, and a cationic photopolymerization initiator, the epoxy group undergoes ring-opening polymerization upon irradiation with light, curing proceeds, and a strong adhesive cured product is obtained. In addition, the vinyl ether-based compound preferentially causes a cationic photopolymerization reaction over a cationic polymerization reaction of a compound having an epoxy group, and thus acts to delay the initiation of polymerization of the compound having an epoxy group. In addition, since the elastic modulus of the polymer of the vinyl ether compound is much lower than that of the polymer of the compound having an epoxy group, the polymer has sufficient tackiness at an early stage after light irradiation. Therefore, the adhesiveness of the curable pressure-sensitive adhesive sheet to the adherend can be increased, and the time from light irradiation to application, that is, the pot life can be extended.

In the second aspect of the present invention, since the adhesive polymer is an acrylic polymer, it has excellent initial adhesive strength in a normal state, easy control of adhesive properties, and the above cationic photopolymerization initiator. Is a photosensitive onium salt compound, so it is stable against heat, can increase the storage stability of the curable adhesive sheet before light irradiation, and is more active as the growth terminal structure reacts at room temperature. The curing reaction after light irradiation and after bonding can proceed reliably at room temperature.

In the method for joining members according to the third aspect of the present invention, when the joining members are bonded to each other via the curable adhesive sheet according to the first or second aspect of the present invention, the curable adhesive is bonded. It is characterized in that the adhesive sheet is irradiated with light and joined, but the cured adhesive sheet has a sufficient initial adhesive force and cohesive force in a normal state, so that it is securely adhered to the joining member, and Since the curing reaction proceeds reliably by irradiation, both joining members can be firmly bonded.

[0068]

The present invention will be clarified by the following non-limiting examples. In the following, “parts” means “parts by weight” unless otherwise specified.

Example 1 In a 2 L separable flask, 30 parts of glycidyl methacrylate, epoxy resin (trade name: Epicoat 82, manufactured by Yuka Shell Epoxy Co., Ltd.)
8) 90 parts, cyclohexane dimethanol divinyl ether (manufactured by ISP) 10 parts, bis (2,6-dimethoxybenzoyl) -2,4,4 as a photoradical polymerization initiator
0.1 parts of trimethylpentylphosphine oxide (manufactured by Ciba Geigy, trade name: Irgacure 1700) and 0.5 parts of a photocationic polymerization initiator (manufactured by Asahi Denka Kogyo, trade name: Optomer SP-170) are made uniform. Then, dissolved oxygen was removed by bubbling with nitrogen gas for 20 minutes to obtain a photopolymerizable composition.

The above photopolymerizable composition was applied to a polyethylene terephthalate film whose surface was subjected to a release treatment to a thickness of 0.1 mm.
The film was coated so as to have a thickness of 3 mm, and another surface of the coated film of the photopolymerizable composition was coated with a polyethylene terephthalate film having a release treatment. Thus, a laminate in which the coating film made of the photopolymerizable composition was sandwiched between the pair of polyethylene terephthalate films was obtained.

Using a fluorescent lamp having a maximum emission wavelength at 400 nm, near-ultraviolet light substantially not containing light in a wavelength region of 360 nm or less is applied to the laminate, and a light intensity of 1 mW / c.
as a m ^2, and irradiated for 10 minutes to obtain a cured pressure-sensitive adhesive sheet.

(Examples 2 to 6 and Comparative Examples 1 and 2) Except that the composition of the photopolymerizable composition used to obtain the curable adhesive sheet was changed as shown in Table 1 below. The
A curable adhesive sheet was produced in the same manner as in Example 1.

(Evaluation) The polyethylene terephthalate film on one side was peeled off from the laminate, and the obtained curable pressure-sensitive adhesive sheet was cut into a size of 25 mm × 25 mm.
mm x length 150mm x thickness 2mm stainless steel plate (S
US304, hereinafter abbreviated to adherend A. ). Next, in the wavelength range of 300 nm to less than 360 nm, the curable adhesive sheet was irradiated with light such that the light intensity became 30 mW / cm ² for 60 seconds. As shown in Table 1, the polyethylene terephthalate film covering the other surface of the curable pressure-sensitive adhesive sheet was peeled off immediately after the light irradiation or after a lapse of a predetermined time (the time until the application after the light irradiation). An adherend B having the same material and the same dimensions as the adherend A was adhered to each other, and a shear adhesion test piece in which the adherends A and B were joined with a curable adhesive sheet was obtained. The shear adhesive strength of the shear adhesive test piece was measured according to JISZ0237 after curing for 7 days after bonding. The results are shown in Table 1 below.

In the evaluation of the shearing adhesive force in Table 1, immediately after light irradiation, 10 minutes after light irradiation, 30 minutes after light irradiation, 60 minutes after light irradiation and 120 minutes after light irradiation, It was the time until the adherend B was applied. In each case, after the application, curing was performed for 7 days, and after the curing, the shear adhesive strength was evaluated.

[0075]

[Table 1]

In Table 1, the epoxy resin 1 is
Yuka Shell Epoxy Co., Ltd., product name: Epicoat 828
Epoxy resin 2 is manufactured by Shin Nippon Rika Co., Ltd., trade name: Rica Resin BPO-20E, cyclohexane dimethanol divinyl ether is a product manufactured by ISP, and triethylene glycol methyl vinyl ether is a product manufactured by BASF.

[0077]

As described above, according to the curable pressure-sensitive adhesive sheet according to the first aspect of the present invention, it contains a tacky polymer, a compound having an epoxy group, a vinyl ether compound, and a cationic photopolymerization initiator. Therefore, it has sufficient tackiness in a normal state, and is surely cured after light irradiation to give a strong adhesive cured product. In addition, since the photocationic polymerization of the vinyl ether compound delays the photocationic polymerization of the compound having an epoxy group, the time from light irradiation until the application, that is, the pot life is kept relatively long. . Therefore, the bonding operation using the curable adhesive sheet can be facilitated. In addition, in the early stage after light irradiation,
Since the elastic modulus of the polymer of the vinyl ether compound is lower than the elastic modulus of the polymer of the compound having an epoxy group, the polymer also has sufficient tackiness.

Claims (3)

[Claims] 1. A curable pressure-sensitive adhesive sheet comprising an adhesive polymer, a compound having an epoxy group, a vinyl ether compound, and a cationic photopolymerization initiator. 2. The curable adhesive sheet according to claim 1, wherein the adhesive polymer is an acrylic polymer, and the cationic photopolymerization initiator is a photosensitive onium salt compound. 3. A bonding method of members, wherein when the bonding members are bonded to each other via the curable adhesive sheet according to claim 1 or 2, the curable adhesive sheet is irradiated with light. .