JPH10120988A - Curing type adhesive sheet and joining of member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a curing type adhesive sheet having good tack and initial adhesive force at the ordinary temperature and exhibiting excellent adhesive force, heat resistance, durability, etc., after cured, to provide a method for joining members to each other with the adhesive sheet, and to provide the joined member. SOLUTION: This curing type adhesive sheet capable of being cured by the addition of activation energy comprises a high mol.wt. polymer, an epoxy group-having compound, and a compound for inducing the ring-opening reaction of epoxy groups. Therein, the content of the epoxy groups in the curing type adhesive sheet is 0.0001-0.015mol/g, and the conversion of the epoxy groups is 0-30% just after the induction of the ring-opening reaction of the epoxy groups and 50-100% after left for 7 days from the time at 25 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a curable adhesive sheet and a method for joining members using the same.

[0002]

2. Description of the Related Art Epoxy resin adhesives have excellent adhesive strength, creep resistance, weather resistance, water resistance, heat resistance, chemical resistance, etc., and can bond a wide range of materials such as metals, plastics and glass. Suitable for automobiles, electric machines,
It is widely used in various fields such as architecture, civil engineering, woodwork, and general use.

However, since epoxy resin adhesives are generally liquid at room temperature, coating unevenness occurs at the time of application, the appearance of the joint ends deteriorates due to sticking out of the adhesive at the time of excessive application, and before curing. Have problems associated with being liquid, such as difficulty in recoating.

To cope with the above problems, for example, Japanese Patent Application Laid-Open No. Sho 60-173076 proposes to use an epoxy resin-based adhesive formed into a sheet or film. However, conventional sheet-like or film-like epoxy resin-based adhesives such as those proposed above are generally inferior in tackiness and lack initial tackiness because they are solid at room temperature, and workability at the time of joining is poor. Due to the problem and lack of initial adhesive strength, it is necessary to adopt a severe joining method such as using a high-temperature and high-pressure press, and it cannot be applied to adherends and joining members that do not have resistance to high-temperature and high-pressure There is a point.

In Japanese Patent Application Laid-Open No. 2-272076,
"Pressure-sensitive thermosetting consisting of photopolymerizable monomer syrup containing acrylic acid ester as a main component, epoxy resin containing no photopolymerizable group, heat-active curing agent for epoxy resin, photoinitiator and photocrosslinking agent. Pressure-sensitive adhesive and pressure-sensitive thermosetting adhesive tape using the same "have been proposed.

However, the pressure-sensitive thermosetting adhesive tape proposed above requires heat-curing in order to cure the epoxy resin, and is difficult to apply to an adherend having poor heat resistance such as plastic. There is.

Further, JP-A-5-506465 discloses that "a radical photopolymerization component such as (meth) acrylate and vinyl ester, a cationic photopolymerization component such as an epoxy compound, and an organometallic complex salt initiator are contained. Pressure-sensitive adhesive and a pressure-sensitive adhesive tape using the same ".

[0008] However, the pressure-sensitive adhesive tape according to the above proposal has already completed the cationic polymerization reaction when it is formed into a tape shape, so that it no longer adheres and cures even if it is irradiated with ultraviolet light at the time of attaching the substrate. However, there is a problem that the adhesive strength cannot be expressed as much as an adhesive.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned conventional problems, the present invention has good tackiness (tack) and initial tackiness at room temperature, and excellent adhesive strength and heat resistance after curing. , A curable adhesive sheet exhibiting durability etc., and
An object of the present invention is to provide a method for joining members using the same and an adhesive member.

[0010]

According to the first aspect of the present invention, there is provided a curable adhesive sheet comprising a high molecular weight polymer, a compound having an epoxy group, and an epoxy group. A curable pressure-sensitive adhesive sheet containing a compound that induces a ring-opening reaction and curable by application of activation energy, wherein the content of the epoxy group in the curable pressure-sensitive adhesive sheet is 0.0001 to 0. .015mol / g
And the conversion of the epoxy group immediately after the activation energy is applied to induce the ring-opening reaction of the epoxy group is 0.
-30% at 25 ° C. and 7%
After standing for days, the conversion of the epoxy groups is in the range of 50 to 100%.

The invention according to claim 2 (hereinafter referred to as "the second invention")
The curable adhesive sheet according to the first aspect is characterized in that the high molecular weight polymer is an acrylic polymer.

The invention according to claim 3 (hereinafter referred to as "third invention")
The curable pressure-sensitive adhesive sheet according to the second invention is the curable pressure-sensitive adhesive sheet according to the second invention, wherein the acrylic polymer is a photopolymerizable composition containing an allylic monomer.
It is characterized by being obtained by photoradical polymerization.

The invention according to claim 4 (hereinafter referred to as the "fourth invention")
The curable adhesive sheet according to the first invention,
In the curable adhesive sheet according to the second or third invention, the compound that induces a ring-opening reaction of the epoxy group is an onium salt catalyst.

The method for joining members according to the invention described in claim 5 (hereinafter referred to as “fifth invention”) is the same as that of the first invention.
Before or after bonding the joining member to the adherend via the curable adhesive sheet according to any of the fourth inventions, the curing type adhesive sheet is provided with an activation energy to form an epoxy group. A step of curing the curable pressure-sensitive adhesive sheet by a polymerization reaction for ring opening.

Further, according to a sixth aspect of the present invention, there is provided a method of joining members according to the fifth aspect of the present invention, wherein the activation energy is less than 360 nm. And the light intensity is 5 m
It is characterized by being ultraviolet light of W / cm ² or more.

The invention according to claim 7 (hereinafter referred to as the "seventh invention")
Described), the at least one surface of the base material,
The curable adhesive sheet according to any of the first to fourth inventions is laminated.

The high molecular weight polymer used for the curable pressure-sensitive adhesive sheet according to the first invention is preferably one having good compatibility with the compound having an epoxy group, and is not particularly limited. Polymer, polyester, polyurethane, polysilicone, polyether, polycarbonate, polystyrene, polyvinyl ether, polyvinyl chloride, polyvinyl acetate, ethylene-vinyl acetate copolymer, polyisobutylene, and the like. Although the above is preferably used, it is possible to utilize a photo-radical polymerization reaction described below,
One or more acrylic polymers are more preferably used in terms of good compatibility with the compound having an epoxy group and excellent performance as an adhesive sheet.

The molecular weight of the high molecular weight polymer is not particularly limited, but the weight average molecular weight is 200,000 to 5
It is preferably 100,000, more preferably 600,000 to 3,000,000. The weight average molecular weight of the high molecular weight polymer is 20
If it is less than 10,000, the cohesive force of the obtained curable pressure-sensitive adhesive sheet becomes insufficient, and it becomes easy to cause peeling due to cohesive failure when attached to an adherend.
The viscosity of the composition comprising the high molecular weight polymer and the compound having an epoxy group becomes high, and it becomes difficult to form the composition into a sheet.

The epoxy group-containing compound used in the curable adhesive sheet according to the first invention can utilize the photocationic polymerization reaction described below and does not contain a photoradical polymerizable group such as a vinyl group. Preferred are, but not particularly limited to, for example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, novolak type epoxy resin, glycidyl ester type epoxy resin, cycloaliphatic epoxy resin, halogenated epoxy resin, poly Alkylene glycol epoxy resins and the like are mentioned, and one or more of these are suitably used.

In the first invention, the content of the epoxy group in the curable adhesive sheet is from 0.0001 to 0.0001.
0.015 mol / g, preferably 0.001 to 0.0
1 mol / g, more preferably 0.002 to 0.0
08 mol / g.

The content of the epoxy group is 0.0001 m
If the amount is less than ol / g, even if the compound having an epoxy group is completely cured, the degree of cross-linking becomes insufficient and sufficient adhesive strength cannot be obtained. The curing rate of the compound having a group becomes too fast, so that the adhesiveness and initial adhesive strength of the curable adhesive sheet become poor, and the workability at the time of joining decreases.

The content of the epoxy group in the curable pressure-sensitive adhesive sheet was determined by the hydrochloric acid-dioxane method as follows.

With respect to a predetermined amount of the curable adhesive sheet, hydrogen chloride dioxane solution / ethanol = 1/1 (weight ratio)
After stirring at room temperature for 5 hours, unreacted hydrogen chloride was subjected to back titration with potassium hydroxide, and the epoxy group content was determined by the following formula. Z (mol / g) = (S ₁ −S ₂ ) × C × f / (Ws ×
1000) Z (mol / g): Content of epoxy group S ₁ (mL): Titration of ethanol solution of potassium hydroxide required for main test S ₂ (mL): Ethanol solution of potassium hydroxide required for blank test C (mol / L): Concentration of ethanol solution of potassium hydroxide used for titration f: Factor of ethanol solution of potassium hydroxide used for titration Ws (g): Sampled amount of titration sample, but titration sample When an acid group such as a carboxyl group is present in the acid, the content of the acid group is determined in advance, and the value is calculated as Z
The value subtracted from the above was defined as the epoxy group content.

The compound for inducing the ring opening reaction of the epoxy group used in the curable adhesive sheet according to the first invention is not particularly limited, but includes an inorganic acid-base complex, a Lewis acid-base complex and the like. Compounds that generate a proton by heat and induce ring-opening reaction of epoxy group, such as onium salts and organometallic complexes, compounds that induce ring-opening reaction of epoxy group by light such as ultraviolet rays. One or more of these are suitably used.

The above onium salts are not particularly restricted but include, for example, diazonium salts, sulfonium salts, iodonium salts and the like, and one or more of these are preferably used.

The above-mentioned organometallic complexes are not particularly restricted but include, for example, iron-allene complexes, titanocene complexes, arylsilanol-aluminum complexes, and one or more of these. Is preferably used.

In the curable pressure-sensitive adhesive sheet according to the first invention, the conversion of the epoxy group immediately after the activation energy is applied to induce the ring-opening reaction of the epoxy group is 0 to 0.
30%, preferably 0 to 20%, and after the ring opening reaction is induced and left at 25 ° C for 7 days, the conversion of the epoxy group is 50 to 100%, preferably 60 to 100%, more preferably Needs to be in the range of 70 to 100%.

The means for imparting activation energy to the epoxy group is not particularly limited, but includes, for example, ultraviolet light, electron beam, X-ray, high frequency, heat and the like. Among them, ultraviolet rays that cause less deterioration of the adherend and the joining member are more preferably used.

If the conversion of the epoxy group immediately after inducing the ring-opening reaction of the epoxy group exceeds 30%, the resulting curable pressure-sensitive adhesive sheet becomes poor in tackiness and initial tackiness, resulting in poor adhesion during bonding. Workability decreases.

In addition, the ring-opening reaction of the epoxy group is induced, and the conversion of the epoxy group after standing at 25 ° C. for 7 days is 50%.
If the amount is less than the above, curing is insufficient, and sufficient adhesive strength cannot be obtained.

The conversion of the epoxy group was determined by the following equation. Conv (%) = (Z ₀ −Z ₁ ) / Z ₀ × 100 Conv (%): Conversion ratio of epoxy group Z ₀ (mol / g): In the curable adhesive sheet before applying activation energy epoxy group content Z ₁ (mol / g): epoxy group content of the curing pressure-sensitive in the adhesive sheet at a time after providing the activation energy, however, Z ₀ and Z ₁ are hydrochloric mentioned above - dioxane It was determined by the method.

The curable adhesive sheet according to the first invention includes:
One or more crosslinkable monomers such as a polyfunctional acrylate monomer or a polyfunctional vinyl monomer in order to improve the heat resistance and the cohesive strength at a high temperature, etc., if necessary within a range not to hinder the achievement of the object of the present invention. Two or more kinds may be contained.

The crosslinkable monomer is not particularly restricted but includes, for example, hexanediol (meth) acrylate, ethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate and 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 the present invention, “(meth) acrylate” means “acrylate” or “methacrylate”.

The curable pressure-sensitive adhesive sheet according to the first aspect of the present invention includes a rosin-based resin, a modified resin, and Rosin resin, terpene resin, terpene phenol resin, aromatic modified terpene resin, C5 or C
9, one or more tackifier resins such as petroleum resin and cumarone indene resin.

In particular, when the adherend to which the curable pressure-sensitive adhesive sheet is applied is a polyolefin, a rosin-based resin among the tackifying resins described above can be used because it can exhibit a strong adhesive force. Modified rosin-based resins, petroleum-based resins, and the like are more preferably used.

Further, the curable pressure-sensitive adhesive sheet according to the first aspect of the present invention may be used, if necessary, in order to improve the coatability of the composition when it is formed into a sheet, as long as the object of the present invention is not hindered. , Acrylic rubber, epichlorohydrin rubber,
One or more of thickeners such as isoprene rubber and butyl rubber, thixotropic agents such as colloidal silica and polyvinylpyrrolidone, and extenders such as calcium carbonate, titanium oxide and clay may be contained.

Further, the curable pressure-sensitive adhesive sheet according to the first invention may further include a glass balloon, an alumina balloon, or the like, if necessary, in order to improve the shearing adhesive force or the like as long as the achievement of the object of the present invention is not hindered. Inorganic hollow bodies such as ceramic balloons, organic hollow bodies such as vinylidene chloride balloons and acrylic balloons, organic spherical bodies such as nylon beads, acrylic beads and silicon beads, and single fibers such as glass, polyester, rayon, nylon and cellulose. Species or two or more species may be contained.

The method for preparing the curable pressure-sensitive adhesive sheet according to the first invention is not particularly limited, but the high molecular weight polymer, the compound having an epoxy group, and the ring-opening reaction of the epoxy group are essential components. A curable adhesive composition comprising an inducing compound and other components to be contained as necessary is coated on a release paper to form a sheet, thereby obtaining a non-support type cured adhesive sheet. May be
Alternatively, a support-type curable pressure-sensitive adhesive sheet may be obtained by using various substrates as a support, coating the curable pressure-sensitive adhesive composition on the substrate, and forming a sheet.

The substrate may be one generally used in the production of pressure-sensitive adhesive sheets, and is not particularly limited. For example, polyethylene terephthalate (PE)
T) Synthetic resin films such as films, cloths, non-woven fabrics, metal foils and the like are mentioned, and are preferably used.

The coating thickness of the curable pressure-sensitive adhesive composition is not particularly limited, and may be appropriately set according to the use and purpose of use of the curable pressure-sensitive adhesive sheet. Although it is not a thing, it is generally preferable that it is 10-1000 micrometers.

Next, the curable adhesive sheet according to the second invention is the same as the curable adhesive sheet according to the first invention,
The high molecular weight polymer is an acrylic polymer.

The acrylic polymer is a homopolymer of alkyl (meth) acrylate monomer or 2
Copolymers of alkyl (meth) acrylate monomers or more, or copolymers of an alkyl (meth) acrylate monomer and a vinyl monomer having an unsaturated bond copolymerizable with the alkyl (meth) acrylate monomer, etc. In the case of a copolymer of an alkyl (meth) acrylate monomer and a vinyl monomer having an unsaturated bond, it is preferable that the unit of the alkyl (meth) acrylate monomer in the copolymer is 20% by weight or more. .

The alkyl (meth) acrylate monomer is not particularly limited, but may be, for example,
Methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, Examples include isononyl (meth) acrylate, isomiristyl (meth) acrylate, hexadecyl (meth) acrylate, octadecyl (meth) acrylate, eicosyl (meth) acrylate, and one or more of these are preferably used. Among them, one or more alkyl (meth) acrylate monomers having an alkyl group having 1 to 14 carbon atoms are more preferably used.

The vinyl monomer having an unsaturated bond copolymerizable with the alkyl (meth) acrylate monomer is not particularly limited, but the storage stability of the resulting curable pressure-sensitive adhesive sheet is not limited. In terms of not inhibiting,
The compound having an epoxy group is preferably non-reactive, for example, (meth) acrylonitrile, N-vinylpyrrolidone, isovoltanyl (meth) acrylate,
Cyclohexyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, N-acryloylmorpholine, benzyl (meth) acrylate, glycidyl (meth) acrylate, N-vinylcaprolactone, N
-Vinylpiperidine and the like, and one or more of these are suitably used.

The polymerization method for obtaining the acrylic polymer is not particularly limited, and conventionally known polymerization methods such as a radical polymerization method, an anion polymerization method, a coordination polymerization method, and a photopolymerization method are suitably employed. .

The structure of the acrylic polymer is not particularly limited, and may be a homopolymer structure, a random copolymer structure, a block copolymer structure, an alternating copolymer structure, a stereoregular structure, or a multi-layer structure. Any structure such as a branched structure, a star-shaped structure, a dendritic structure, a ladder structure, a ring structure, and a helical structure may be used.

Further, whether the acrylic polymer has good compatibility with the compound having an epoxy group,
Alternatively, it is preferable that the compound does not cause macro phase separation even if it is incompatible with the compound having an epoxy group. Note that the macro phase separation means that the acrylic polymer and the compound having an epoxy group completely undergo phase separation,
That is, it means that one or both of the acrylic polymer and the compound having an epoxy group are separated in a transparent state, and does not mean a state where the phase is merely clouded due to microphase separation.

The molecular weight of the acrylic polymer is not particularly limited, but is preferably 200,000 to 5,000,000 in weight average molecular weight, and 600,000 to 3,000,000.
More preferably, it is one million. If the weight-average molecular weight of the acrylic polymer is less than 200,000, the resulting curable pressure-sensitive adhesive sheet has insufficient cohesive force and tends to peel off due to stringing at the time of application. When it exceeds, the viscosity of the curable adhesive composition comprising an acrylic polymer, a compound having an epoxy group, and a compound that induces a ring-opening reaction of the epoxy group becomes too high, and it is difficult to mold the composition into a sheet. It will be difficult.

Next, the curable adhesive sheet according to the third invention is the same as the curable adhesive sheet according to the second invention,
The acrylic polymer is obtained by subjecting a photopolymerizable composition containing an acrylic monomer to radical photopolymerization.

The above-mentioned photopolymerizable composition contains an acrylic monomer and a photoradical polymerization initiator as essential components. If necessary, an unsaturated monomer copolymerizable with the acrylic monomer may be used as long as the object of the present invention is not hindered. It contains a vinyl monomer having a bond.

The acrylic monomer is not particularly limited, but includes various alkyl (meth) acrylate monomers exemplified in the description of the curable adhesive sheet according to the second invention. One or more kinds are preferably used, and among them, one or more kinds of alkyl (meth) acrylate monomers having an alkyl group having 1 to 14 carbon atoms are more preferably used.

Examples of the vinyl monomer having an unsaturated bond copolymerizable with the alkyl (meth) acrylate monomer include various vinyl monomers exemplified in the description of the curable adhesive sheet according to the second invention. And one or more of them are suitably used.

As the photoradical polymerization initiator, 36
A cleavage type compound that is activated by light in a wavelength region of 0 nm or more and does not cause energy transfer to a photocationic polymerization initiator that opens an epoxy group described below is preferable, and is not particularly limited. But, for example, 4
-(2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone, α-hydroxy-α, α ′
-Dimethylacetophenone, methoxyacetophenone,
Acetophenone-based compounds such as 2,2-dimethoxy-2-phenylacetophenone; benzoin ethyl ether;
Benzoin ether compounds such as benzoin isopropyl ether; ketal compounds such as benzyldimethyl ketal; halogenated ketones; acylphosphine oxides; acylphosphonates; bis- (2,6-dimethoxybenzoyl) -2,4,4- Trimethylpentyl phosphine oxide and the like can be mentioned, and one or more of these are suitably used.
Acylphosphine oxide, acylphosphonate, bis- (2,6-dimethoxybenzoyl) -2,4,4-
One or more of trimethylpentylphosphine oxide and the like are more preferably used.

The content of the alkyl (meth) acrylate monomer in the photopolymerizable composition is not particularly limited, but is preferably 30 to 95% by weight, and more preferably 40 to 60% by weight. Is more preferred.

If the content of the above alkyl (meth) acrylate monomer is less than 30% by weight, the resulting acrylic polymer will have insufficient tackiness at room temperature and initial tackiness. The cohesive force of the obtained acrylic polymer decreases.

When a vinyl monomer having an unsaturated bond copolymerizable with the alkyl (meth) acrylate monomer is used in combination, the content of the vinyl monomer in the photopolymerizable composition is particularly limited. However, it is preferably 2 to 40% by weight, and 20 to 3% by weight.
More preferably, it is 0% by weight.

When the content of the vinyl monomer is 2% by weight
When the amount is less than the above, the cohesive force of the obtained acrylic polymer becomes insufficient. On the other hand, when the amount exceeds 40% by weight, the obtained acrylic polymer becomes hard and the adhesiveness at room temperature and the initial adhesive force become poor.

The content of the photo-radical polymerization initiator in the photo-polymerizable composition is not particularly limited, but is preferably 0.05 to 5% by weight.
More preferably, it is 0.1 to 1% by weight.

When the content of the above photo-radical polymerization initiator is 0.1.
When the amount is less than 05% by weight, the polymerization of the obtained acrylic polymer is not sufficiently performed. On the contrary, when the amount exceeds 5% by weight, the molecular weight of the obtained acrylic polymer becomes low and the heat resistance becomes insufficient.

The above-mentioned photopolymerizable composition may contain, if necessary, a compound having an epoxy group and a ring-opening reaction of the epoxy group as long as the object of the present invention is not hindered. An optical cationic polymerization initiator may be contained.

The lamps used for light irradiation as a trigger for photo-radical polymerization of the photopolymerizable composition are not particularly limited. For example, low-pressure mercury lamps, medium-pressure mercury lamps, and high-pressure mercury lamps , 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.

In the third invention, when a compound having an epoxy group and a cationic photopolymerization initiator coexist in the photopolymerizable composition, the direct light from the lamps is 3
Since a large amount of light having a wavelength of less than 60 nm is emitted and a photocationic polymerization reaction of a compound having an epoxy group is easily caused at the same time, in order to cause only a photoradical polymerization of the photopolymerizable composition, a wavelength region of less than 360 nm is required. Near-ultraviolet light substantially free of light is preferable. Examples of a method for obtaining the near-ultraviolet light include using a cut filter in combination with the lamps. However, when a fluorescent lamp having a maximum emission wavelength in the 420 nm region is used, light in a wavelength region of less than 360 nm is not substantially contained, so that it is not necessary to use a cut filter together.

The upper limit wavelength of the irradiation light in the near ultraviolet light is not particularly limited, but is generally 450 nm.
For example, when an acylphosphone-based photoradical polymerization initiator is used as the photoradical polymerization initiator, polymerization is sufficiently performed even with light having a wavelength around 400 nm.

The light intensity of the near ultraviolet light is not particularly limited, but the light intensity in the wavelength region of 360 to 450 nm is preferably 0.05 to 20 mW / cm ² . When the light intensity is less than 0.05 mW / cm ² , the polymerization does not proceed sufficiently and the polymerization time becomes longer.
When it exceeds 0 mW / cm ² , when a compound having an epoxy group and a cationic photopolymerization initiator coexist, cationic photopolymerization tends to occur.

In the above-mentioned photo-radical polymerization process, the radical polymerization reaction is inhibited by oxygen in the air and oxygen dissolved in the photo-polymerizable composition. Therefore, light irradiation is performed by a method capable of removing the inhibition of the oxygen reaction. Is preferred. Examples of such a method include, but are not particularly limited to, for example, a method of covering the photopolymerizable composition with a PET film or a Teflon film and irradiating light through the film, nitrogen gas, carbon dioxide gas, or the like. A method in which polymerization is performed in an inert zone having a light-transmitting window in which oxygen has been replaced by an inert gas.

In the above method of polymerizing in the inert zone, the polymerization rate of the photopolymerizable composition is 99.7%.
In order to sufficiently complete the process up to the above, the oxygen concentration in the inert zone is preferably 5000 ppm or less. Also, the molecular weight of the acrylic polymer obtained by photopolymerizing the photopolymerizable composition decreases with an increase in the oxygen concentration in the inert zone, so that the molecular weight is almost the same as that in the case of polymerization under completely inert conditions. In order to do so, the oxygen concentration in the inert zone is more preferably 1000 ppm or less. Furthermore, since the surface layer portion of the photopolymerizable composition is more susceptible to oxygen than the inner layer portion, the oxygen concentration in the inert zone is 300 ppm or less in order to impart the same cohesive force to the surface layer portion as the inner layer portion. Is particularly preferred.

Next, the curable pressure-sensitive adhesive sheet according to the fourth invention is the same as the curable pressure-sensitive adhesive sheet according to the first, second, or third invention described above, except that the compound capable of inducing a ring-opening reaction of an epoxy group. Is an onium salt catalyst.

The onium salt catalyst is not particularly limited, but is inactive to light in a wavelength region of 360 nm or more, is active in light in a wavelength region of less than 360 nm, and has no thermal reactivity. In this respect, aromatic onium salts are preferably used.

The aromatic onium salts are not particularly limited, but include, for example, aromatic diazonium salts, aromatic iodonium salts, aromatic sulfonium salts and the like. It is preferably used.

Specific examples of the above-mentioned aromatic onium salts are "Optomer SP-150" (manufactured by Asahi Denka Kogyo KK), "Optmer SP-170" (manufactured by Asahi Denka Kogyo KK) and "UVE" Commercially available products such as "-1014" (manufactured by General Electronics Co., Ltd.) and trade name "CD-1012" (manufactured by Sartomer Co., Ltd.) are used, and one or more of these are suitably used.

The lamps used for light irradiation for activating the photocationic polymerization initiator are not particularly limited, but those having an emission distribution in a wavelength region of 300 to 360 nm are usually used. Preferably, 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-excited mercury lamp, a metal halide lamp, and the like are preferably used.

In the case of performing the light irradiation, in order to prevent only the surface layer of the curable pressure-sensitive adhesive sheet from being cured and to uniformly cure the inside of the sheet, light in a wavelength region of 300 nm or less is cut and irradiated. Is preferred.

In the above-mentioned cationic photopolymerization process,
Although there is no polymerization inhibition by oxygen, it is preferable to reduce the humidity of the irradiation atmosphere as much as possible in order to prevent deactivation of the cationic activity due to humidity.

The curable adhesive sheet according to the fourth invention includes:
If necessary, a compound that generates a proton by heat, such as an inorganic acid-base complex or a Lewis acid-base complex, may be contained, if necessary, as long as the object of the present invention is not hindered. good.

By including the above compound which generates protons by heat in the curable adhesive sheet, not only the light energy but also the compound having an epoxy group can be cured using both light energy and heat energy. It becomes possible.

Next, the method for joining members according to the fifth invention is as follows.
Before or after bonding the joining member to the adherend via the curable adhesive sheet according to any of the first to fourth inventions described above, activation energy is applied to the curable adhesive sheet. And curing the curable pressure-sensitive adhesive sheet by a polymerization reaction to open the epoxy group.

The above joining method includes the steps of joining the adherend and the joining member via the curable adhesive sheet according to any of the first to fourth inventions before or after joining. UV, electron beam, X
Apply activation energy by wire, high frequency, heat, etc.
The method includes a step of opening the epoxy group in the compound having an epoxy group contained in the curable pressure-sensitive adhesive sheet to cause a polymerization reaction to cure the curable pressure-sensitive adhesive sheet.

In the above joining method, the step of applying activation energy to the curable adhesive sheet to open the epoxy group and cause a polymerization reaction may be performed before joining the adherend and the joining member. As described in the description of the curable pressure-sensitive adhesive sheet, the conversion of the epoxy group immediately after the ring-opening reaction is induced is suppressed to the range of 0 to 30%. It has good tackiness and initial tackiness, and can be joined without any hindrance.

The step of opening the epoxy group by the activation energy may be carried out before or after the joining of the adherend and the joining member as described above, regardless of the case. The polymerization reaction of the compound proceeds with time at room temperature, and as described in the description of the curable pressure-sensitive adhesive sheet according to the first invention, induces a ring-opening reaction to cause 2
After standing at 5 ° C. for 7 days, the conversion of the epoxy group is 50-1.
Since the content is within the range of 00%, a bonded article having excellent adhesive strength, heat resistance, durability and the like can be finally obtained.

Next, the method for joining members according to the sixth aspect of the invention is as follows.
In the member joining method according to the fifth aspect, the activation energy is in a wavelength region of less than 360 nm, and the light intensity is ultraviolet light of 5 mW / cm ² or more.

Epo contained in the curable adhesive sheet
Properly promotes photocationic polymerization of compounds with xyl groups
In order for the light to be transmitted,
Degree is 5mW / cm^TwoIt is necessary to be more than
But 10-300mW / cm ^TwoIs preferably
10-100mW / cm^TwoIs more preferable.
The light intensity is 5 mW / cm^TwoLess than the photocation
The polymerization reaction hardly proceeds.

As the lamps used for light irradiation for performing the photocationic polymerization reaction, various lamps exemplified in the description of the curable adhesive sheet according to the fourth invention are suitably used.

Next, the pressure-sensitive adhesive member according to the seventh invention is characterized in that the curable pressure-sensitive adhesive sheet according to any one of the first to fourth inventions described above is laminated on at least one surface of a substrate. .

The substrate used for the pressure-sensitive adhesive member according to the seventh aspect of the present invention is not particularly limited. For example, non-woven fabrics such as rayon-based and cellulosic;
Films or sheets such as polyester, polypropylene, polystyrene, polyimide, cellophane; foams such as polyethylene foam, urethane foam, chloroprene foam, and vinyl chloride foam; resin plates such as polystyrene, ABS, acrylic, polypropylene, polyethylene, and polycarbonate Steel, stainless steel,
Metal sheets or plates such as copper and aluminum; glass; wood; paper;
In addition, the shape of the base material is not limited to a film shape, a sheet shape, a foam shape, a plate shape, and the like.
It may have a spherical shape or a shape having an aspherical surface.

The method of laminating the curable pressure-sensitive adhesive sheet on at least one surface of the substrate is not particularly limited, and may be carried out by a conventional method using a conventionally known device such as a laminator, a roll, a press and the like.

The shape of the adhesive member according to the seventh aspect of the present invention is not particularly limited, but is preferably a tape or sheet including a double-sided adhesive tape.

(Function) The curable pressure-sensitive adhesive sheet according to the first invention comprises a high molecular weight polymer, a compound having an epoxy group,
And a compound that induces a ring opening reaction of the epoxy group,
A curable pressure-sensitive adhesive sheet that can be cured by application of activation energy, wherein the curable pressure-sensitive adhesive sheet contains a specific amount of epoxy groups, and imparts activation energy,
Immediately after inducing the ring-opening reaction of the epoxy group and at 25 ° C, 7
Since the conversion ratio of the epoxy group after standing for a day is within a specific range, it has good tackiness and initial tackiness, and exhibits excellent adhesive strength, heat resistance, durability and the like after curing.

The curable adhesive sheet according to the second aspect of the present invention is the curable adhesive sheet according to the first aspect of the present invention.
Since an acrylic polymer is used as the high molecular weight polymer, it has better tackiness and initial tackiness, and exhibits more excellent adhesive strength, heat resistance, durability and the like after curing.

Further, the curable pressure-sensitive adhesive sheet according to the third invention is an acrylic curable pressure-sensitive adhesive sheet obtained by subjecting the curable pressure-sensitive adhesive sheet according to the second invention to photoradical polymerization of a photopolymerizable composition containing an acrylic monomer. Since an acrylic polymer is used, an acrylic polymer (high molecular weight polymer) can be easily obtained only by light energy without using thermal energy.

Further, the curable pressure-sensitive adhesive sheet according to the fourth invention is the curable pressure-sensitive adhesive sheet according to the first, second or third invention, wherein the onium salt catalyst for opening the epoxy group is contained. Therefore, the curable adhesive sheet can be cured only by light energy without requiring high heat or high pressure. Therefore, the curable pressure-sensitive adhesive sheet can be suitably used for joining an adherend or a joining member having poor heat resistance and pressure resistance.

Next, the method for joining members according to the fifth invention is as follows.
In joining the adherend and the joining member via the curable adhesive sheet according to any of the first to fourth inventions described above, before or after joining, the activation energy is applied to the curable adhesive sheet. Since the method includes a step of curing the curable adhesive sheet by a polymerization reaction of giving and ring-opening the epoxy group, the joining can be performed with less restrictions on the joining step and with good workability. Further, the joined article joined by the above joining method is excellent in adhesive strength, heat resistance, durability and the like.

The member joining method according to the sixth aspect of the present invention is the member joining method according to the fifth aspect of the present invention, wherein the activation energy is an ultraviolet ray having a wavelength region of less than 360 nm and a light intensity of 5 mW / cm ² or more. Since high heat and high pressure are not required, bonding of an adherend and a bonding member having poor heat resistance and pressure resistance can be easily performed. Also, the joints joined by the above joining method have adhesive strength, heat resistance,
Excellent durability and the like.

Further, the pressure-sensitive adhesive member according to the seventh aspect of the present invention is formed by previously laminating the curable pressure-sensitive adhesive sheet according to any of the first to fourth aspects on at least one surface of the base material. In addition to being able to be performed, the resulting joint is excellent in adhesive strength, heat resistance, durability and the like.

[0094]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 36 g of 2-ethylhexyl acrylate was placed in a 4-liter separable flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen gas inlet.
84 g of N-vinylpyrrolidone and 98 g of ethyl acetate were charged, and the monomer mixed solution was bubbled with nitrogen gas for 20 minutes to remove dissolved oxygen. Then, the inside of the separable flask was replaced with nitrogen gas and refluxed with stirring. Temperature was reached. Next, a solution prepared by diluting 0.024 g of 1,1-di (t-hexylperoxy) -3,3,5-trimethylcyclohexane with 1 g of ethyl acetate as a polymerization initiator was added to the polymerization system. One hour later, a solution obtained by diluting 0.036 g of 1,1-di (t-hexylperoxy) 3,3,5-trimethylcyclohexane with 1 g of ethyl acetate was added to the polymerization system. Further, 2 hours, 3 hours and 4 hours after the initiation of the polymerization, 0.048 g of di (3,5,5-trimethylhexanoyl) peroxide and 0.12 g
And solutions prepared by diluting 0.36 g with 1 g of ethyl acetate were charged into the polymerization system. 7 from the first polymerization initiator
After an hour, an acrylic polymer having a weight average molecular weight of about 500,000 was obtained. Next, after cooling the polymerization system to room temperature, 36 g of an epoxy resin (trade name “Epicoat 828”, manufactured by Yuka Shell Epoxy) and a cationic photopolymerization initiator (trade name “Optomer SP-170”, Asahi Denka Kogyo KK) Was added and uniformly stirred and mixed to obtain a curable adhesive composition.

[0096] A coating thickness of 300 µm (d
ry), and dried in a dryer at 100 ° C. for 2 minutes to obtain a curable adhesive sheet. The epoxy group content in the obtained curable adhesive sheet was 0.001.
It was 5 mol / g. Also, the conversion of epoxy groups immediately after irradiating the curable adhesive sheet with light having a light intensity of 5 mW / cm ² or more in the wavelength region of 300 to 360 nm is 10
%, And the conversion of epoxy groups after irradiation and standing at 25 ° C. for 7 days was 75%.

[0097] The curable pressure-sensitive adhesive sheet obtained above
Room temperature T peeling force, room temperature shearing force and initial adhesive strength are measured according to JIS Z
-0237 "Adhesive tape / adhesive sheet test method"
Room temperature T peeling force was 0.5 kg / c
m, normal temperature shearing force is 4 kg / cm ^Two, Initial adhesive strength is 300
gf.

Further, the curable pressure-sensitive adhesive sheet obtained above had a light intensity of 5 mW / W at a wavelength range of 300 to 360 nm.
The adherends were adhered by irradiating light of cm ² or more, and the room temperature T peeling force and the room temperature shear force immediately after the adhesion and after standing at 25 ° C. for 7 days were measured in accordance with JIS Z-0237.
The room temperature T peeling force immediately after bonding is 0.6 kg / cm, the room temperature shearing force is 4.5 kg / cm ² , the room temperature T peeling force after standing at 25 ° C. for 7 days is 1 kg / cm, and the room temperature shearing force is 10 kg / cm 2.
kg / cm ² . The initial adhesive strength before bonding was 400 gf.

Example 2 In a 2-liter separable flask, 70 g of 2-ethylhexyl acrylate, N
-30 g of vinylpyrrolidone, 30 g of epoxy resin "Epicoat 828", 0.05 g of bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide as a photoradical polymerization initiator and as a photocationic polymerization initiator "Optomer SP-170"
0.5 g was uniformly stirred and mixed to obtain a photopolymerizable composition.

The photopolymerizable composition obtained above was subjected to a release treatment to a PET film having a coating thickness of 300 μm (dry).
After coating so that the coating surface is released from PET
A laminate was formed by coating with a film. Then 400 nm
A fluorescent lamp having a maximum emission wavelength is used, and near-ultraviolet light substantially not including light in a wavelength region of 360 nm or less is irradiated to the laminate for 5 minutes so that the light intensity becomes 1 mW / cm ^2. A curable adhesive sheet was obtained. The content of the epoxy group in the obtained curable adhesive sheet is 0.0015 m.
ol / g. Next, the curable pressure-sensitive adhesive sheet obtained above was irradiated with light having a light intensity of 5 mW / cm ² or more in a wavelength region of 300 to 360 nm. The conversion of the epoxy groups immediately after irradiation is 10%,
After standing for 7 days, the conversion of epoxy groups was 75%.

When the room-temperature T-peeling force, room-temperature shearing force and initial adhesive force of the curable pressure-sensitive adhesive sheet obtained above were measured in the same manner as in Example 1, the room-temperature T-peeling force was 0.6 kg.
/ Cm, normal temperature shear strength was 4.3 kg / cm ² , and initial adhesive strength was 350 gf.

Further, using the curable pressure-sensitive adhesive sheet obtained above, an adherend was adhered in the same manner as in Example 1, and the room-temperature T-peeling force immediately after lamination and after standing for 7 days at 25 ° C. The room temperature shearing force was measured in the same manner as in Example 1. The room temperature T peeling force immediately after bonding is 0.8 kg / cm, the room temperature shearing force is 5 kg / cm ² , and the room temperature T after standing at 25 ° C. for 7 days.
Peeling force: 1.8 kg / cm, normal temperature shearing force: 13 kg / c
m ² . The initial adhesive strength before bonding is 400g
f.

[0103]

As described above, the curable pressure-sensitive adhesive sheet according to the present invention has good tackiness and initial tackiness at room temperature, and has excellent adhesive strength, heat resistance and durability after curing. Since it exhibits properties and the like, it is suitably used for joining various adherends and joining members with good workability. In addition, since it can be cured only by light energy without requiring high heat or high pressure, it can also be suitably used for joining adherends and joining members having poor heat resistance and pressure resistance.

Further, according to the method of joining members according to the present invention, various types of adherends and joining members can be joined with good workability with little restriction on the joining process, and without using high heat or high pressure. Since bonding using only light energy is also possible, bonding of an adherend or a bonding member having poor heat resistance, pressure resistance, or the like can be easily performed.

Further, the joined article obtained by using the curable pressure-sensitive adhesive sheet according to the present invention by the method of joining members according to the present invention is excellent in adhesive strength, heat resistance, durability and the like, and is suitably used for various applications. .

Further, the pressure-sensitive adhesive member according to the present invention can join various members with good workability, and the obtained joint is excellent in adhesive strength, heat resistance, durability and the like, and is suitably used for various applications.

Claims (7)

[Claims] 1. A curable adhesive sheet which comprises a high molecular weight polymer, a compound having an epoxy group, and a compound which induces a ring opening reaction of an epoxy group, and which can be cured by applying activation energy. The content of the epoxy group in the curable adhesive sheet is 0.0001 to 0.015.
mol / g, and the conversion rate of the epoxy group immediately after the activation energy is applied to induce the ring-opening reaction of the epoxy group is 0 to 30%. , After standing for 7 days, the conversion of epoxy group is 50 ~
A curable adhesive sheet characterized by being in the range of 100%. 2. The curable adhesive sheet according to claim 1, wherein the high molecular weight polymer is an acrylic polymer. 3. The curable adhesive according to claim 2, wherein the acrylic polymer is obtained by subjecting a photopolymerizable composition containing an acrylic monomer to photoradical polymerization. Sheet. 4. The curable adhesive sheet according to claim 1, wherein the compound that induces a ring opening reaction of the epoxy group is an onium salt catalyst. 5. A method for activating the curable adhesive sheet before or after attaching the joining member to an adherend via the curable adhesive sheet according to claim 1. A method of joining members, comprising a step of curing the curable pressure-sensitive adhesive sheet by a polymerization reaction of applying energy to open the epoxy group. 6. The method according to claim 5, wherein the activation energy is in a wavelength region of less than 360 nm and the light intensity is ultraviolet light having a light intensity of 5 mW / cm ² or more. 7. The method according to claim 1, wherein at least one surface of the substrate is provided.
A pressure-sensitive adhesive member, wherein the curable pressure-sensitive adhesive sheet according to any one of the above is laminated.