JPH10147754A - Curable adhesive sheet and method of joining members - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive at room temperature, which can be cured by irradiating light, has excellent adhesive strength to an adherend, and can be applied to an adherend having low heat resistance. Provided is a curable adhesive sheet. The pressure-sensitive adhesive sheet is formed using a pressure-sensitive adhesive polymer such as an acrylic polymer, and has an absorbance of 0.001 to 0 for light having a wavelength of 350 nm per sheet thickness of 100 μm in the pressure-sensitive adhesive sheet. .2
A curable adhesive sheet containing an epoxy group-containing compound and a photocationic polymerization catalyst for inducing a photoring-opening cation reaction of an epoxy group in the sheet as described below.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a curable pressure-sensitive adhesive sheet and a method for joining members, and more particularly, to a curable pressure-sensitive adhesive sheet which is normally tacky and is cured by light irradiation. The present invention relates to an adhesive sheet 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, the acrylic pressure-sensitive adhesive could not exhibit high peel resistance like the adhesive.

[0003] Therefore, a curable adhesive has been proposed which has both the easy workability of an acrylic pressure-sensitive adhesive and the high bonding strength and coating strength comparable to an adhesive. For example, JP-A-2-272076 discloses an adhesive tape using a pressure-sensitive thermosetting adhesive composed of a photopolymerizable composition containing an acrylate monomer and an epoxy resin.

When members are to be joined to each other using the adhesive tape described in the above-mentioned prior art, after irradiating the photopolymerizable composition with light to polymerize an acrylate monomer and develop adhesiveness, By sticking to an adherend and curing the epoxy resin by heating after sticking, a strong adhesive force can be obtained.

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. That is, there is a problem that the material of the adherend is limited.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a member which has a sufficient initial adhesive strength under normal conditions, can be easily cured by irradiating light, and can be used for a member having insufficient heat resistance. It is an object of the present invention to provide a curable pressure-sensitive adhesive sheet which can be bonded to a sheet and a method for bonding members using the curable pressure-sensitive adhesive sheet.

[0007]

Means for Solving the Problems Although not yet known, the inventors of the present application have previously described an acrylic polymer as a curable adhesive which can be used for joining members having insufficient heat resistance.
A curable adhesive sheet containing an epoxy resin and a compound which is exposed to light to induce ring opening of an epoxy group was proposed.
In this curable adhesive sheet, since the epoxy resin is cured by light irradiation, the adhesive can be applied to the adherend only by irradiating light before or after attaching the curable adhesive sheet to the adherend. The curable adhesive sheet can be firmly bonded, and the heat resistance of the adherend does not matter.

However, when a thick curable adhesive sheet is formed, it is difficult for light to reach a deep portion, so that it takes a long time to cure to a deep portion or it can be sufficiently cured to a deep portion. Or not. Therefore, as a result of further study on a curable adhesive sheet which is cured by irradiating the light, it has been found that if the absorbance of the sheet is adjusted, it is possible to quickly cure to a deep part, and the present invention has been accomplished. .

That is, the curable adhesive sheet according to the first aspect of the present invention is a pressure-sensitive adhesive sheet, comprising a compound having an epoxy group, and a cationic photopolymerization catalyst.
It is characterized in that the absorbance for light having a wavelength of 350 nm per sheet thickness of 100 μm is 0.001 to 0.2.

[0010] The invention according to claim 2 is characterized in that (meth)
A photopolymerizable composition containing an acrylate monomer, a compound having an epoxy group, a photocationic polymerization catalyst, and a photoradical polymerization initiator activated by light in a wavelength region of 360 nm or more has a wavelength region of 360 nm or more. The compound having an epoxy group and the cationic photopolymerization catalyst are held and sheeted by an acrylic acid polymer obtained by photoradical polymerization of the (meth) acrylic ester monomer by irradiating the above light. It is characterized by.

Further, in the curable adhesive sheet according to the third aspect of the present invention, the cationic photopolymerization catalyst is an onium salt compound activated by irradiation with light. In the invention according to claim 4, the alkyl group has 1 carbon atom.
(Meth) acrylate monomer (a)
A vinyl monomer having an unsaturated bond copolymerizable with a (meth) acrylate monomer (b), a photo-radical polymerization initiator activated by light in a wavelength region of 360 nm or more (c), and a compound containing an epoxy group (d ), And 30
A curable composition formed by irradiating light in a wavelength region of 360 nm or more with a composition formed by mixing a photocationic polymerization catalyst (e) that induces a ring-opening reaction of an epoxy group with light of 0 nm or more and less than 360 nm. An adhesive sheet comprising: an epoxy group in a compound containing an epoxy group in the sheet;
A photocationic polymerization catalyst that induces a ring-opening reaction of an epoxy group with light having a wavelength of at least nm and less than 360 nm is contained in an unreacted state.

According to a fifth aspect of the present invention, there is provided a method for joining members, wherein the joining members are bonded to each other via the curable adhesive sheet according to any one of the first to fourth aspects.
The curable adhesive sheet is irradiated with light having a wavelength of less than 360 nm and a light intensity of 5 mW / cm ² or more.

Hereinafter, the present invention will be described in detail. Compound having an epoxy group The compound having an epoxy group used in the curable pressure-sensitive adhesive sheet of the present invention undergoes ring-opening polymerization by the action of a photocationic polymerization catalyst when irradiated with light. Is used to cure

For compounds containing an epoxy group,
It is not particularly limited as long as it has an epoxy group,
For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, novolak type epoxy resin, glycidyl ester compound, glycidylamine compound and the like can be exemplified.

Photocationic Polymerization Catalyst In the curable pressure-sensitive adhesive sheet of the present invention, the curing proceeds by causing a ring-opening reaction of the epoxy group of the compound having an epoxy group to cause polymerization. In order to induce the ring opening of the epoxy group, a photocationic polymerization catalyst is blended as described above, and the photocationic polymerization catalyst may be any arbitrary one that induces the ring opening of the epoxy group by irradiating light. Photocationic polymerization catalysts may be used.

Preferably, the photocationic polymerization catalyst is activated by irradiation with light in a wavelength region of 300 nm or more and less than 360 nm.
Since light of a wavelength less than that is used, the energy intensity is high, and thus ring opening of the epoxy group can be rapidly advanced. Also, preferably, a compound having low thermocatalytic activity at around 20 to 80 ° C. is preferable from the viewpoint of enhancing storage stability. As such a preferable compound, for example, iron-
Organometallic complexes such as allene complexes, titanocene complexes, and arylsilanol-aluminum complexes; and onium salt compounds such as aromatic diazonium salts, aromatic iodonium salts, aromatic sulfonium salts, and pyridinium salts, more preferably As described in claim 4,
Onium salt compounds are used depending on the sensitivity in the photosensitive wavelength region.

More specifically, examples of the onium salt compound include Optomer SP-150 (manufactured by Asahi Denka Kogyo), Optomer SP-170 (manufactured by Asahi Denka Kogyo),
VE-1014 (manufactured by General Electronics), C
A commercially available compound such as D-1012 (manufactured by Sartomer) can be used.

The lamp used for the light irradiation includes:
Those having an emission distribution at a wavelength of 360 nm or less are used. For example, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, chemical lamps, black light lamps,
A microwave excitation mercury lamp, a metal halide lamp, or 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.

Adhesive Polymer The curable pressure-sensitive adhesive sheet according to the present invention comprises:
It is characterized by containing the above-mentioned compound having an epoxy group and a cationic photopolymerization catalyst, but the adhesive sheet contains an adhesive polymer in order to exhibit adhesiveness.

The adhesive polymer may be compatible or incompatible with the compound having an epoxy group and the cationic photopolymerization catalyst as long as they do not cause macrophase separation. You may. Here, the macro phase separation refers to a phenomenon in which the adhesive polymer completely separates the phase with the compound having an epoxy group and the cationic photopolymerization catalyst, and any one of the adhesive polymer, the compound having an epoxy group, and the cationic photopolymerization catalyst. Or a state in which all are separated in a transparent state, and a state different from a state in which micro phase separation merely causes cloudiness.

The adhesive polymer which can be used in the present invention has been conventionally used to constitute an adhesive unless it causes macro phase separation with the compound having an epoxy group and the cationic photopolymerization catalyst as described above. Any suitable high molecular weight polymer can be used. Examples of such tacky polymers include acrylic polymers,
Polyesters, polyurethanes, silicones, polyethers, polycarbonates, polyvinyl ethers, polyvinyl chlorides, polyvinyl acetates, polyisobutylenes, and the like can be given. May be a copolymer containing a monomer as a main component.

The molecular weight of the adhesive polymer is preferably large, and the weight average molecular weight is preferably in the range of 100,000 to 5,000,000, more preferably 200,000 to 3,000,000, and further preferably 600 to 2,000,000. If the weight average molecular weight of the adhesive polymer is less than 100,000, the cohesive force of the curable pressure-sensitive adhesive sheet is insufficient, stringing may occur at the time of application, and peeling may occur. In some cases, the viscosity of the composition containing the polymer and the resin having an epoxy group becomes high, and the sheet cannot be formed.

Among the various polymers described above, the polymer is commonly used as a main component of the pressure-sensitive adhesive in order to exhibit a superior initial tackiness, and the control of the pressure-sensitive adhesive properties is easy. It is preferable to use an acrylic polymer as described above.

The structure of the acrylic polymer is not particularly limited, and may be, for example, a homopolymer structure, a random copolymer structure, a block copolymer structure, an alternating copolymer structure, a stereoregular structure, or a multibranched structure. , A star-shaped structure, a dendritic structure, a ladder structure, a ring structure, a helical structure and the like.

A more preferred example of the acrylic polymer is a polymer containing a unit composed of (meth) acrylic ester in an amount of 20% by weight or more in the acrylic polymer, wherein the alkyl group has 1 to 14 carbon atoms. A polymer or copolymer of the (meth) acrylate monomer (a) may be mentioned.

The above-mentioned copolymer includes an alkyl (meth) acrylate monomer (a) and a vinyl monomer (b) having an unsaturated bond copolymerizable with the alkyl (meth) acrylate monomer (a). And copolymers. The method for producing such a copolymer is not particularly limited, and it can be produced by a known method such as radical polymerization, anionic polymerization, coordination polymerization, or photopolymerization.

The alkyl (meth) acrylate monomer (a) includes methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-
Examples thereof include octyl (meth) acrylate, isononyl (meth) acrylate, and isomyristyl (meth) acrylate.

The vinyl monomer (b) is not particularly limited as long as it is a compound having an unsaturated bond copolymerizable with the alkyl (meth) acrylate monomer (a). In order to enhance the property, a vinyl monomer which is not reactive with the epoxy group contained in the curable adhesive sheet is preferable.

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 vinyl monomer (b) include:
Examples thereof include (meth) acrylonitrile, N-vinylpyrrolidone, isovoltanyl (meth) acrylate, N-acryloylmorpholine, benzyl (meth) acrylate, glycidyl (meth) acrylate, N-vinylcaprolactone, and N-vinylpiperidine.

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

Since a cationic photopolymerization catalyst is used, curing of the curable pressure-sensitive adhesive sheet can be performed by irradiating light. That is, only by employing a single method of irradiating light, not only can the curable adhesive sheet be obtained from the photopolymerizable composition, but also the curing of the curable adhesive layer can be performed. Can play. However,
In this case, it is necessary to use light having different wavelength ranges from the light irradiated when forming the acrylic polymer by photoradical polymerization and the light irradiated when curing the curable adhesive sheet. is there.

Further, 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, when the photoradical polymerization is performed, the photoradical polymerization is performed by irradiating light in a wavelength region of 360 nm or more, and a ring opening reaction of an epoxy group is induced to be cured. It is desirable to use light of this type.

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 catalyst with light of less than 360 nm are preferred. Preferred examples of such a photo-radical 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 such as benzoin ethyl ether and benzoin propyl ether Ether compounds; ketal derivative compounds such as benzyl dimethyl ketal; halogenated ketones; acylphosphine oxides; acylphosphonates; 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.

As the lamp used for light irradiation in the photoradical polymerization, for example, 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 microwave excitation mercury lamp, a metal halide lamp, and the like can be used.

Blending Ratio In the curable pressure-sensitive adhesive sheet according to the present invention, the blending ratio of the adhesive polymer and the compound having an epoxy group depends on the desired initial adhesive strength, adhesive strength after curing, and rough surface. It is appropriately determined according to the adhesive force and is not particularly limited, but is preferably an acrylic polymer 10
The compound having an epoxy group is 10 to 3 parts by weight with respect to 0 parts by weight.
It is blended at a ratio of 00 parts by weight.

In the curable adhesive sheet according to the present invention, the compounding ratio of the compound having an epoxy group and the cationic photopolymerization catalyst is such that the absorbance at a wavelength of 350 nm per sheet thickness of 100 μm of the curable adhesive sheet is 100 μm. It is selected to be in the range of 0.001 to 0.2. When the absorbance is smaller than 0.001, the content of the photocationic polymerization catalyst is too small to obtain a sufficient curing rate, or the epoxy resin contained in the curable adhesive sheet has an epoxy group. The content becomes small, and it becomes impossible to obtain an adhesive cured product that can obtain sufficient adhesive strength. Conversely, when the absorbance is greater than 0.2, when the curable pressure-sensitive adhesive sheet is made thick, light does not sufficiently spread to a deep portion, and curing can be uniformly advanced in the curable pressure-sensitive adhesive sheet. It becomes impossible, and it becomes impossible to obtain sufficient adhesive strength. Preferably, the absorbance is from 0.01 to 0.15, more preferably from 0.015
０．１0.13.

Other Additives In addition to the acrylic polymer, the compound having an epoxy group, and the cationic photopolymerization catalyst, the curable pressure-sensitive adhesive sheet according to the present invention may be any of known additives as long as the object of the present invention is not impaired. A tackifier resin, an extender and the like may be appropriately compounded.

For example, for the purpose of improving 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, butyl rubber, etc., thixotropic agents such as colloidal silica, polyvinylpyrrolidone, etc., and increasing amounts of calcium carbonate, titanium oxide, clay, etc. An agent may be added.

Further, in order to provide a high-strength shear adhesive force when the adhesive sheet is formed, inorganic hollow bodies such as glass balloons, alumina balloons, and ceramic balloons; 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 fibers are blended, it is possible to add a fibrous chip to the composition. High shear strength can be obtained.

Production of Curable Adhesive Sheet The production method of the curable adhesive sheet according to the present invention is not particularly limited, and various methods such as a hot melt method, a casting coating method, and a UV polymerization method can be used. For example, in the casting coating method, the above-mentioned adhesive polymer, a compound having an epoxy group and a cationic photopolymerization catalyst are blended, and a resin composition obtained by adding a tackifier resin or the like as necessary is appropriately used. The method of molding into a sheet by the method, or the UV polymerization method, includes the above monomer component for obtaining an acrylic polymer by photoradical polymerization, a photoradical polymerization initiator, a compound having an epoxy group, and a photocationic polymerization catalyst The photopolymerizable composition is formed into a sheet, and the acrylic monomer is irradiated with light before or after the molding to irradiate the acrylic monomer. And a method in which the local polymerized acrylic polymer, may be any appropriate method.

Preferred examples of the production of the curable adhesive sheet according to the present invention by the above-mentioned UV polymerization method include:
As described in claim 4, the alkyl group has 1 to 1 carbon atoms.
4, an alkyl (meth) acrylate monomer, a vinyl monomer having an unsaturated bond copolymerizable with the alkyl (meth) acrylate monomer, a photoradical polymerization initiator activated by light in a wavelength region of 360 nm or more, A compound having an epoxy group;
A photopolymerizable composition is prepared by mixing a photo-cationic polymerization catalyst that induces a ring-opening reaction of an epoxy group when irradiated with light having a wavelength of nm, and is irradiated with light having a wavelength region exceeding 360 nm. A curable adhesive sheet comprising an acrylic polymer formed in a sheet by radical polymerization, and the epoxy group and the cationic photopolymerization catalyst contained in the sheet without being reacted.

In the curable adhesive sheet thus obtained, the epoxy group and the cationic photopolymerization catalyst which induces a ring-opening reaction of the epoxy group with light having a wavelength of 300 to 360 nm remain unreacted. Will do.

Therefore, immediately before or after laminating the curable adhesive sheet, it can be easily cured by irradiating light having a wavelength of 300 to 360 nm. For example, the epoxy group content in the sheet before irradiation with light having a wavelength of 300 to 360 nm is 0.0001 to
When a curable pressure-sensitive adhesive sheet of 0.01 mol / g is obtained, it varies depending on the wavelength and intensity of light to be irradiated, but when the conversion of epoxy groups is 0 to 30% immediately after irradiation, 7% at 25 ° C.
After curing for days, the conversion of epoxy groups in the sheet is 50
-100%.

Form of Use of the Curable Adhesive Sheet The curable adhesive sheet according to the present invention can be used as it is, for example, when bonding a bonding member to an adherend so as to be interposed and bonded therebetween. May be used in the form of a double-sided pressure-sensitive adhesive tape, or may be formed as a pressure-sensitive adhesive layer on at least one surface of a suitable substrate such as a synthetic resin film or cloth.

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. , Various foams such as polyvinyl chloride, resin plates made of various synthetic resins such as polystyrene, ABS, acrylic, polypropylene, and polyethylene, steel, stainless steel,
Sheets or plates made of various metals such as copper and aluminum, glass, wood, paper, cloth, and the like can be used.
There is no 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.

[0050] In the bonding method of members according to the invention according to the bonding method according to claim 5 of the member, the joining member via the adhesive and pressure-sensitive adhesive sheet according to any one of claims 1 to 4 as described above to the adherend When bonding, ie, before or after bonding, light is irradiated to cure the curable adhesive sheet. In this case, preferably, "before bonding" means
It means before the bonding and before the curing of the resin having the 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.

In curing, preferably, 36
Having a wavelength of less than 0 nm and a light intensity of 5 mW / cm ²
The above light is used. Light having a wavelength exceeding 360 nm does not have sufficient energy intensity, and may require a long time for curing. Similarly, when light having a light intensity of less than 5 mW / cm ² is used, similarly, a long time is required for curing. It may be.

If 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.

[0053] In the adhesive and pressure-sensitive adhesive sheet according to the action the present invention can be easily applied to an adherend to have a sufficient initial adhesive strength by the adhesive polymer. In addition, by irradiating light before or after the application to the adherend, the photocationic polymerization catalyst is activated to cause ring-opening polymerization of the compound having an epoxy group, thereby giving a strong adhesive cured product. Therefore,
The curable adhesive sheet is firmly joined to the adherend.

Further, in the curable adhesive sheet according to the present invention, the compound having an epoxy group and the cationic photopolymerization catalyst are contained so that the absorbance of the sheet is in the range of 0.001 to 0.2. As a result, the curing speed after the light irradiation proceeds sufficiently fast, the curing proceeds reliably even in the deep part, and an adhesive cured product having high adhesive strength can be obtained.

[0055]

The present invention will be clarified by the following non-limiting examples.

Example 1 In a 2 L separable flask, 10 g of n-butyl acrylate, 30 g of glycidyl methacrylate, 60 g of an epoxy resin (manufactured by Yuka Shell Epoxy Co., Ltd., Epicoat 828), and bis (photo-radical polymerization initiator) 2,6-dimethoxybenzoyl)-
2,4,4-trimethylpentylphosphine oxide (Ciba Geigy, trade name: Irgacure 1700)
0.10 g and a cationic photopolymerization catalyst (manufactured by Asahi Denka Kogyo Co., Ltd.
(Trade name: Optomer SP-170) 0.5 g was stirred and mixed until uniform, and then dissolved oxygen was removed by bubbling with nitrogen gas for 20 minutes to obtain a photopolymerizable composition.

The above photopolymerizable composition is applied to a polyethylene terephthalate (PET) film whose surface has been subjected to a release treatment so as to have a thickness of 0.3 mm or 1 mm. The composition film was coated with another PET film whose surface had been release-treated. 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 thus obtained so that the light intensity becomes 1 mW / cm ^2. To obtain a curable adhesive sheet.

The absorbance of the above-mentioned curable pressure-sensitive adhesive sheet at a wavelength of 350 nm per sheet thickness of 100 μm was measured using a self-recording spectrophotometer Model U-3500 manufactured by Hitachi, Ltd. and found to be 0.046.

The above-mentioned curable pressure-sensitive adhesive sheet is irradiated with light having a wavelength of 300 nm or more and less than 350 nm and 5 mW / cm ² or more for 30 seconds, and then through the curable pressure-sensitive adhesive sheet. The adherends made of stainless steel (SUS-304) were stuck together and cured at 25 ° C. for 7 days. The room-temperature shear adhesive strength and the normal-temperature T peel force before the light irradiation, and the normal-temperature shear adhesive force and the normal-temperature T peel force after the above-mentioned 7-day curing were determined by J
It measured according to ISZ0237. The results are shown in Table 1 below.

Example 2 As a photopolymerizable composition, 30 g of glycidyl methacrylate, 50 g of an epoxy resin (trade name: Epicoat 828, manufactured by Yuka Shell Epoxy Co., Ltd.)
Epoxy resin (Shin Nippon Rika Co., Ltd., trade name: Rica Resin B)
PO-60E), 0.10 g of bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide (trade name: Irgacure 1700, manufactured by Ciba Geigy) as a photoradical polymerization initiator, and a photocation After uniformly stirring and mixing 0.5 g of a polymerization catalyst (trade name: Optomer SP-170, manufactured by Asahi Denka Kogyo KK),
By bubbling with nitrogen gas for 20 minutes,
A curable pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that a material from which dissolved oxygen had been removed was used.

The thickness of the curable pressure-sensitive adhesive sheet is 10
The absorbance at a wavelength of 350 nm per 0 μm is
0.082. Further, the room-temperature shear adhesive strength and the normal-temperature T peeling force of the curable adhesive sheet were evaluated in the same manner as in Example 1. The results are shown in Table 1 below.

(Example 3) The compounding amount of glycidyl methacrylate was 20 g, and the compounding amount of an epoxy resin (manufactured by Yuka Shell Epoxy, product number: Epicoat 828) was 50 g.
Epoxy resin (Shin Nippon Rika Co., Ltd., trade name: Rica Resin B)
Example 1 was repeated except that a further 20 g of PE-60E) was added, and the amount of the cationic photopolymerization catalyst was changed to 1.0 g.
In the same manner as in the above, a photopolymerizable composition was obtained, and a curable adhesive sheet was produced.

The thickness of the curable pressure-sensitive adhesive sheet was 10
The absorbance at a wavelength of 350 nm per 0 μm is 0.
It was 10. The room-temperature shear adhesive strength and the normal-temperature T peeling force of the curable adhesive sheet were evaluated in the same manner as in Example 1. The results are shown in Table 1 below.

Comparative Example 1 The amount of n-butyl acrylate was changed from 10 g to 45 g, and 15 g of N-vinylpyrrolidone was used in place of glycidyl methacrylate. Epoxy resin (trade name: Epicoat 828, manufactured by Yuka Shell Epoxy Co., Ltd.) A photopolymerizable composition was obtained in the same manner as in Example 1 except that the amount of used was 40 g, and a curable adhesive sheet was obtained in the same manner as in Example 1.

Sheet thickness of curable adhesive sheet 100 μm
The absorbance at a wavelength of 350 nm per m is 0.25
Met. The adhesive strength of this curable adhesive sheet was measured in Example 1.
The evaluation was performed in the same manner as described above. The results are shown in Table 2 below.

Comparative Example 2 45 g of 2-ethylhexyl acrylate, 15 g of N-vinylpyrrolidone, epoxy resin (trade name: Epicoat 82, manufactured by Yuka Shell Epoxy Co., Ltd.)
8) 40 g, bis (2,6) as a photoradical polymerization initiator
0.10 g of -dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide (manufactured by Ciba Geigy, trade name: Irgacure 1700) and a cationic photopolymerization catalyst (manufactured by Asahi Denka Kogyo, trade name: Optomer SP-)
170) A photopolymerizable composition was obtained in the same manner as in Example 1 except that 0.5 g was used, and a curable adhesive sheet was obtained.

The sheet thickness of the curable adhesive sheet is 100 μm.
The absorbance at a wavelength of 350 nm per m is 0.23
Met. The adhesive strength of this curable adhesive sheet was measured in Example 1.
The evaluation was performed in the same manner as described above. The results are shown in Table 2 below.

[0068]

[Table 1]

[0069]

[Table 2]

As is apparent from Table 2, in Comparative Examples 1 and 2, the above-mentioned 350 n in the curable pressure-sensitive adhesive sheet may be due to absorption of ultraviolet rays by the N-vinylpyrrolidone compounded.
The absorbance at a wavelength of m was as high as 0.25 and 0.23. For this reason, regardless of whether the curable adhesive sheet having a thickness of 0.3 mm or 1.0 mm was obtained, in Comparative Examples 1 and 2, shear adhesion after curing for 7 days after irradiation with light. When a cured type pressure-sensitive adhesive sheet having a low strength and a thickness of 1.0 mm was obtained, the shear adhesive strength after curing for 7 days was extremely low. Similarly, in the case of the T-peeling force, in the case of a curable pressure-sensitive adhesive sheet having a thickness of 1.0 mm, the peeling force was almost constant after curing for 7 days in both Comparative Examples 1 and 2. Did not increase.

On the other hand, in Examples 1 to 3, even when the film thickness is 1.0 mm, the shear adhesive force and the T-peeling force are drastically increased after curing for 7 days. It can be seen that the curing by light irradiation proceeds sufficiently and reliably even in the thick-walled curable adhesive sheet.

[0072]

According to the curable pressure-sensitive adhesive sheet according to the first aspect of the present invention, the pressure-sensitive adhesive sheet contains a compound having an epoxy group and a photocationic polymerization catalyst in the pressure-sensitive adhesive sheet, and has a wavelength at a sheet thickness of 100 μm. Since the epoxy group-containing compound and the cationic photopolymerization catalyst are contained so that the absorbance with respect to light at 350 nm falls within the above-described specific range, even when a thick cured adhesive sheet is produced, Curing by light irradiation surely proceeds to a deep part. Therefore, even in the case of a thick curable adhesive sheet, by irradiating light before or after attaching to an adherend, it is possible to reliably obtain an adhesive cured product having high adhesive strength. it can.

Further, since the curable pressure-sensitive adhesive sheet according to the present invention uses an adhesive sheet as described above, it can be easily adhered to an adherend by utilizing the initial adhesive force under normal conditions. . Therefore, by irradiating light after being attached to the adherend or before attaching to the adherend, the curable adhesive sheet adhered to the adherend can be cured, and furthermore, press or the like Strong adhesion can be obtained without the need for curing under pressure. Therefore, the present invention can also be applied to a joining member that is deformed under pressure curing conditions. In addition, since heat is not required for curing, it can be applied to a joining member having a problem in heat resistance.

According to the second aspect of the present invention, in the curable adhesive sheet, a (meth) acrylate monomer, a compound having an epoxy group, a photocationic polymerization catalyst, and a light in a wavelength region of 360 nm or more. To a photopolymerizable composition containing a photoradical polymerization initiator activated by
Since the acrylic polymer is formed by photoradical polymerization of the (meth) acrylate monomer by irradiating light in a wavelength region of 60 nm or more, the adherence of the acrylic polymer usually causes the adherend to adhere to the adherend. Adhesion can be easily made. In addition, since the epoxy group and the cationic photopolymerization catalyst are not reacted and held by the acrylic polymer to form a sheet, curing is started by irradiating light as in the invention of claim 1. be able to.

According to the third aspect of the present invention, since the onium salt compound activated by light irradiation is used as the photocationic polymerization catalyst, the heat-resistant storage stability of the curable adhesive sheet is improved. At the same time, by light irradiation, the ring-opening polymerization of the compound having an epoxy group can be promptly advanced, and the curing of the curable adhesive sheet can be accelerated.

According to the fourth aspect of the present invention, the photopolymerizable composition containing the specific (meth) acrylate monomer and the vinyl monomer is irradiated with light in a wavelength region of 360 nm or more to perform photoradical polymerization. Thus, an acrylic polymer is formed, and adhesion to an adherend is easily performed by utilizing the adhesive force of the acrylic polymer. Moreover, in the curable adhesive sheet, the compound having an epoxy group and the cationic photopolymerization catalyst remain unreacted, and the photocationic polymerization catalyst has a high energy intensity of 360 nm.
Is activated by light of less than 360 n
By irradiating light of less than m, the curing reaction can proceed promptly.

In the method of joining members according to the fifth aspect, the curable adhesive sheet according to any one of the first to fourth aspects is applied to the member.
Light in the wavelength region with a high energy intensity of less than 60 nm,
Moreover, since the irradiation is performed so that the light intensity becomes 5 mW / cm ² or more, the curing of the curable adhesive sheet proceeds rapidly, and the joining members can be firmly and easily joined to each other.

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Claims (5)

[Claims] 1. An adhesive sheet comprising a compound having an epoxy group and a cationic photopolymerization catalyst, and having an absorbance of 0.001 to 0.2 for light having a wavelength of 350 nm per sheet thickness of 100 μm. Curable adhesive sheet characterized by the following. 2. A photopolymerizable composition comprising a (meth) acrylate monomer, a compound having an epoxy group, a photocationic polymerization catalyst, and a photoradical polymerization initiator activated by light in a wavelength region of 360 nm or more. 360 in the composition
The compound having an epoxy group and the cationic photopolymerization catalyst are held by an acrylic acid polymer obtained by irradiating light in a wavelength region of not less than nm with the photoradical polymerization of the (meth) acrylic acid ester monomer. The curable pressure-sensitive adhesive sheet according to claim 1, wherein the curable pressure-sensitive adhesive sheet is formed. 3. The curable adhesive sheet according to claim 1, wherein the cationic photopolymerization catalyst is an onium salt compound activated by light irradiation. 4. A (meth) acrylate monomer (a) having an alkyl group having 1 to 14 carbon atoms, a vinyl monomer (b) having an unsaturated bond copolymerizable with the (meth) acrylate monomer, and a wavelength of 360 nm or more. Photo-radical polymerization initiator (c) activated by light in the region, compound (d) containing an epoxy group, and
A composition obtained by mixing a cationic photopolymerization catalyst (e) for inducing a ring-opening reaction of an epoxy group with light having a wavelength of less than 0 nm,
A curable pressure-sensitive adhesive sheet formed by irradiating light in a wavelength region of at least 300 nm, wherein an epoxy group in a compound containing an epoxy group in the sheet and 300 nm or more,
2. The curable pressure-sensitive adhesive sheet according to claim 1, wherein a photocationic polymerization catalyst that induces a ring-opening reaction of an epoxy group with light of less than nm is contained in an unreacted state. 5. When bonding the bonding members together via the curable adhesive sheet according to any one of claims 1 to 4,
A method for joining members, wherein the curable adhesive sheet is irradiated with light having a wavelength of less than 360 nm and a light intensity of 5 mW / cm ² or more.