JPH115953A - Vibration-damping bonding method and vibration-damping structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration-damping bonding method that can easily bond adherends to each other with a high bond strength and, at the same time, can impart excellent vibration damping and sound insulating properties. SOLUTION: This vibration-damping bonding method comprises: providing a curable pressure-sensitive adhesive sheet comprising a compsn., which comprises an acrylic polymer, an epoxy-contg. compd., and a cationic photopolymn. initiator, the compsn. being curable upon exposure to light of wavelengths ranging from 300 to 370 nm; and bonding adherends to each other through the adhesive sheet while irradiating the adhesive sheet with light.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joining method capable of obtaining a structure excellent in soundproofing and vibration damping effects, and a vibration damping structure obtained by the joining method.
The present invention relates to a vibration damping bonding method and a vibration damping structure using a curable adhesive sheet that is cured by light irradiation.

[0002]

2. Description of the Related Art Conventionally, in joining members together, a mechanical joining method such as a screw or welding, or a joining method using an adhesive or an adhesive has been widely used. However, when the members are joined by a mechanical joining method, the vibration damping effect and the soundproofing effect are not sufficient, the stress is easily concentrated on the joints, and it is difficult to secure confidentiality. There were drawbacks.

[0003] On the other hand, in the joining method using an adhesive, since the adhesive is generally in a liquid state, application unevenness occurs at the time of application, and the appearance of the joined portion is impaired due to bleeding when applied excessively. There was a problem. Also,
When an adhesive is used, although sufficient adhesive strength can be obtained, the working environment is deteriorated due to the volatilization of harmful volatile components such as solvents, and it is necessary to fix it using a jig or the like until curing is sufficiently advanced. There were problems that had to be done.

In order to solve the above-mentioned problems of the liquid adhesive, there has been proposed an adhesive sheet formed by molding an epoxy resin-based adhesive into a sheet or a film (Japanese Patent Application Laid-Open No. 60-173076). ). In this type of adhesive sheet, the content of harmful volatile components is small, and sufficient adhesive strength can be obtained. However, since the initial adhesive strength is low and it has no temporary fixing property, there is a problem in workability at the time of joining. In addition, it has to be heated at a high temperature for curing, and cannot be used for joining members having insufficient heat resistance.

Further, when the adhesive sheet is used for joining a member having a three-dimensional shape such as a wavy surface, the adhesive sheet tends to peel off from the member due to shrinkage of the adhesive sheet during heat curing. There was also a disadvantage that there was. In addition, the vibration damping and soundproofing effects of the joints were not sufficient.

On the other hand, a pressure-sensitive adhesive sheet formed by sheet-forming a pressure-sensitive adhesive such as an acrylic pressure-sensitive adhesive is also used. The pressure-sensitive adhesive sheet has a low content of harmful volatile components and has sufficient flexibility to suppress vibration. It is also excellent in effect and soundproofing effect. However, it is difficult to develop an adhesive strength equivalent to that of an adhesive or an adhesive sheet, since the elasticity is designed to be low in order to develop the adhesiveness. Therefore, it could not be used for applications requiring high adhesive strength.

Heretofore, as a vibration damping method and a soundproofing method, a method of increasing the mass and rigidity of a member made of metal or other material used for equipment has also been used. However, this type of method increases the mass of the entire device and cannot be used for applications that require light weight.

Further, a vibration-damping or sound-insulating material layer (hereinafter, simply referred to as a vibration-damping material layer) made of rubber, asphalt, various thermoplastic or thermosetting resins, ultraviolet curable resins, or the like is formed on a plate-like member. There are also known ways to do this. However, it has been difficult to achieve sufficient vibration damping and soundproofing performance with a vibration damping material layer using rubber, asphalt, or various thermoplastic or thermosetting resins. In addition, since rubber and asphalt have poor moldability, it has been difficult to mold them into a sheet and use them.

Further, in a vibration damping material layer using rubber, asphalt or various thermoplastic resins,
There is also a problem that a sufficient damping effect and soundproofing effect cannot be obtained.

Further, the thermoplastic resin and the thermosetting resin cannot be applied to a member having poor heat resistance or a member which is adversely affected by heating in use, and has a large shrinkage force during heat curing. Therefore, when applied to a plate material such as a thin plate, the plate material is deformed by the residual stress of the vibration damping material layer, and the commercial value may be significantly impaired.

On the other hand, an example of a vibration damping and soundproofing method using an ultraviolet-curable resin is disclosed in Japanese Patent Application Laid-Open No. Sho 59-204550. In this method, a coating layer made of an ultraviolet-curable resin composition obtained by blending a photopolymerization initiator on the surface of a thin plate is formed, and the coating layer is irradiated with ultraviolet rays, whereby an interface between the coating layer and the thin plate is formed. It is said that the vibration suppression and soundproofing effects can be obtained by making the hardness of the coating layer lower than the hardness of the other surface side of the coating layer.

However, in this method, it is necessary to continuously irradiate the light until the curing of the ultraviolet-curable resin composition is completed. Therefore, it cannot be used for joining members that do not transmit light. In addition, when the other member is directly bonded to the surface where the coating layer is exposed after forming the coating layer, it is necessary to newly form an adhesive layer on the coating layer, which complicates the process. There was a disadvantage.

[0013]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks of the conventional vibration damping / soundproofing method, to enable members to be easily joined together, and to provide an excellent vibration damping / soundproofing effect. An object of the present invention is to provide a joining method that can be exerted, has less restrictions on applied members, and is less likely to impair the appearance of a joining portion, and a vibration damping structure obtained by the joining method.

[0014]

According to a first aspect of the present invention, there is provided a composition comprising an acrylic polymer, a compound having an epoxy group, and a cationic photopolymerization initiator, the composition being cured by irradiation with light. A curable pressure-sensitive adhesive sheet made of: is prepared, and when the members to be joined are joined via the curable pressure-sensitive adhesive sheet, 300
A vibration damping bonding method characterized by irradiating light having a wavelength of about 370 nm.

Further, a vibration damping structure according to a second aspect of the present invention is obtained by the vibration damping joining method according to the first aspect of the present invention, wherein the first member and the second member are made of acrylic. A system polymer, a compound having an epoxy group, and a cationic photopolymerization initiator, which are joined via a curable adhesive sheet using a composition that is cured by irradiation with light. . In addition, since sound is also vibration, the expression “vibration suppression” may be used below as including a soundproofing effect.

Hereinafter, the present invention will be described in detail. (Acrylic Polymer) In the present invention, the acrylic polymer is used for imparting pressure-sensitive adhesiveness to the curable adhesive sheet. In this case, in order to provide pressure-sensitive adhesiveness, the curable adhesive sheet is preferably configured to have one or more ball tacks in an atmosphere at 25 ° C., and more preferably three or more at room temperature. It is configured as follows.

In order to obtain pressure-sensitive adhesiveness, it is necessary that the balance between wettability to an adherend and cohesion is appropriate. Then, in order to obtain a cohesive force, the above-mentioned acrylic polymer is used.

The acrylic polymer is not particularly limited as long as pressure-sensitive adhesiveness can be obtained. Examples thereof include 2-hydroxyethyl (meth) acrylate,
-Hydroxypropyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 5-hydroxypentyl (meth) acrylate, 6-hydroxyhexyl (meth) ) Acrylate, 3-hydroxy-3-methylbutyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, pentaerythritol tri (meth) acrylate, 2-[(meth) acryloyloxy] ethyl-2-hydroxy -Such as ethyl phthalic acid
Compounds with OH groups, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth)
Acrylate, tert-butyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth)
Acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, isomiristyl (meth) acrylate, stearyl (meth) acrylate,
Isobornyl (meth) acrylate, benzyl (meth)
Examples thereof include homopolymers and copolymers of monomers such as acrylate, 2-butoxyethyl (meth) acrylate, 2-phenoxyethyl (meth) acrylate, glycidyl (meth) acrylate, and tetrahydrfurfuryl (meth) acrylate. it can.

In the present specification, (meth) acrylate is used as a general term for acrylate and methacrylate. When an acrylic copolymer is used as the acrylic polymer, a copolymer of a (meth) acrylate monomer and a vinyl monomer having an unsaturated bond copolymerizable with the (meth) acrylate monomer is used. . In this case, an acrylic polymer that is non-reactive with a compound having an epoxy group described below is preferable from the viewpoint of enhancing storage stability. Therefore, as the vinyl monomer, a carboxyl group-containing compound such as acrylic acid or methacrylic acid or an acid is used. It is not preferable to use a compound having a anhydride skeleton such as maleic anhydride.

The acrylic polymer may be used in combination of a plurality of types. The molecular weight of the acrylic polymer is not particularly limited, but in order to maintain the shape of the curable adhesive sheet, the weight average molecular weight is 4
It is preferably at least 100,000, and preferably at most 5,000,000 in order to exhibit sufficient adhesiveness.

The method for producing the acrylic polymer is not particularly limited, but photoradical polymerization or thermal radical polymerization is preferred since the type of monomer is not limited.

When an acrylic polymer is produced by radical polymerization, a monomer component to be radically polymerized to form the acrylic polymer, a radical polymerization initiator, a compound having an epoxy group described below, and a cationic photopolymerization An acrylic polymer can be formed in the sheet by subjecting the composition containing the initiator to sheet formation and then performing radical polymerization. However, after obtaining a radically polymerized acrylic polymer, a compound having an epoxy group and a photo-cationic polymerization initiator may be mixed with the acrylic polymer to form a sheet.

When radical polymerization is carried out by light, preferably, the radical photopolymerization initiator is
A photo-radical polymerization initiator activated by light having a wavelength longer than 370 nm is used. As such a photo-radical polymerization initiator, for example, 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2- Propyl) ketone, α-hydroxy-α, α′-dimethylacetophenone, methoxyacetophenone, 2,2-dimethoxy-2
Acetophenone derivative compounds such as phenylacetophenone; benzoin ether compounds such as benzoin ethyl ether and benzoin propyl ether; ketal derivative compounds such as benzyl dimethyl ketal; halogenated ketones; acylphosphine oxides; acylphosphonates; , 6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxides.

When radical polymerization is caused by utilizing heat, AIBN (2,2'-azobis-isobutyronitrile) and AMBN (2,2'-azobis-2-methylbutyi) are used as polymerization initiators. General-purpose thermal radical polymerization initiators such as azo compounds such as nitronitrile) and peroxide compounds such as benzoyl peroxide (BPO) and lauroyl peroxide (LPO) can be used.

(Compound Having Epoxy Group) In the present invention, the above-described compound having an epoxy group is blended in order to cure the curable adhesive sheet by irradiating light.
That is, the compound having an epoxy group undergoes ring-opening polymerization by the cation-forming species generated by irradiating the photocationic polymerization initiator with light, and the curable adhesive sheet is cured.

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

Also, an epoxy group-containing oligomer can be suitably used, and examples thereof include a bisphenol A type epoxy oligomer (for example, Epicoat 1001, 1002, manufactured by Yuka Shell Epoxy Co., Ltd.).

Further, an addition polymer of the above-mentioned epoxy group-containing monomer or oligomer may be used, and examples thereof include glycidylated polyester, glycidylated polyurethane, and glycidylated polyacryl.

Further, these resins may be blended or added with other resin components or the like to increase flexibility, and to improve adhesion or bending force. CTBN (butadiene-acrylonitrile rubber containing a terminal carboxyl group) modified epoxy resin; epoxy resin in which various rubbers such as acrylic rubber, NBR, SBR, butyl rubber, or isoprene rubber are dispersed; epoxy modified with the above liquid rubber Resins; epoxy resins obtained by adding various resins such as acryl, urethane, urea, polyester, and styrene; chelate-modified epoxy resins; and polyol-modified epoxy resins.

(Photocationic Polymerization Initiator) In the present invention, the photocationic polymerization initiator is activated by irradiation with light to generate a photocationic polymerization initiator, and is polymerized by irradiation with light. Can be initiated, so that polymerization can be initiated with relatively low energy.

As the light, any suitable light such as ultraviolet light or visible light can be used.
Is used. The cationic photopolymerization initiator is not particularly limited as long as the ring opening reaction of the epoxy group can be induced by light having the wavelength used.
A compound which induces a ring-opening reaction of an epoxy group by light having a wavelength of 00 to 370 nm and is inactive in a wavelength region exceeding 370 nm is preferably used. Examples of such a compound include aromatic diazonium salts and aromatic compounds. Onium salts such as halonium salts and aromatic sulfonium salts can be mentioned. Specific examples of such onium salts include, for example, Optomer SP-150 (manufactured by Asahi Denka Kogyo), Optomer SP-170 (manufactured by Asahi Denka Kogyo),
UVE-1014 (manufactured by General Electronics),
CD-1012 (manufactured by Sartomer), Sun-Aid SI-
60L (manufactured by Sanshin Chemical Industries), Sun-Aid SI-80L
(Manufactured by Sanshin Chemical Industry Co., Ltd.), Sun-Aid SI-100L (manufactured by Sanshin Chemical Industry Co., Ltd.), CI-2064 (manufactured by Nippon Soda Co., Ltd.),
CI-2639 (Nippon Soda Co., Ltd.), CI-2624 (Nippon Soda Co., Ltd.), CI-2481 (Nippon Soda Co., Ltd.) and the like can be exemplified.

The above cationic photopolymerization initiators may be used alone or in combination of two or more. Further, two-stage curing may be performed using a plurality of cationic photopolymerization initiators having different effective wavelengths. The curable pressure-sensitive adhesive sheet may contain a known thickener, filler, colorant, flame retardant, and the like as long as the object of the present invention is not impaired.

(Blending Ratio) In the present invention, the blending ratio of the acrylic polymer and the compound having an epoxy group is appropriately determined according to the desired initial adhesive strength, the adhesive strength after curing, and the like. Although not limited, preferably, the compound having an epoxy group is blended in an amount of 10 to 300 parts by weight based on 100 parts by weight of the acrylic polymer.

The compounding ratio of the compound having an epoxy group is 1
If the amount is less than 0 parts by weight, it may not be possible to obtain sufficient adhesive strength even when cured by irradiating light.
If it exceeds 300 parts by weight, the relative blending ratio of the acrylic polymer may decrease, and a sufficient initial adhesive strength may not be obtained.

The mixing ratio of the above-mentioned cationic photopolymerization initiator is not particularly limited because it varies depending on the kind thereof, but preferably, the cationic photopolymerization initiator is added to 100 parts by weight of the compound having an epoxy group. The agent will range from 0.01 to 5 parts by weight. When the proportion of the cationic photopolymerization initiator is less than 0.01 parts by weight, the ring-opening reaction of the epoxy group may not be able to proceed sufficiently even when irradiated with light, and an adhesive cured product having a high adhesive strength may be obtained. May not be obtained, and even if it is added in an amount exceeding 5 parts by weight, the effect of promoting curing may not be further increased, and conversely, the initial adhesive strength may be reduced.

(Formation of Curable Adhesive Sheet) Regarding the method of forming a sheet containing the acrylic polymer, the compound having an epoxy group and the cationic photopolymerization initiator,
There is no particular limitation, and a commonly used general coating technique can be employed. For example, a method of obtaining a curable adhesive sheet by dissolving a composition containing each of the above components in a solvent, coating and drying, or a monomer having an acrylic polymer as a raw material of an acrylic polymer, a compound having an epoxy group, and a photocation. After applying a composition containing a polymerization initiator and a photo-radical polymerization initiator, the bulk polymerization is performed by irradiating a long-wavelength ultraviolet ray that does not cause energy transfer to the photo-cationic polymerization initiator but causes a photo-radical polymerization reaction. And the like.

The light source used for initiating photoradical polymerization and photocation polymerization is not particularly limited.
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 can be used. In this case, it is desirable to cut and irradiate light having a wavelength of 320 nm or less in order to prevent curing of only the surface layer portion and promote internal curing.

(Substrate) In the bonding method of the present invention, the above-mentioned curable pressure-sensitive adhesive sheet has a form of a double-sided pressure-sensitive adhesive tape, for example, in order to interpose and adhere between adherends. Is done. In this case, the curable pressure-sensitive adhesive sheet does not have a substrate and may be composed of only a pressure-sensitive adhesive layer, or may have a form in which pressure-sensitive adhesive layers are formed on both surfaces of a substrate. You may.

Examples of the base material include various nonwoven fabrics such as rayon or cellulose, and various synthetic materials such as polyethylene, polyester, cellophane, polypropylene, polystyrene, polyimide, nylon, polymethyl (meth) acrylate, polyvinyl chloride, and polycarbonate. Various foams such as foamed polyethylene, foamed polyurethane, neoprene foam, and foamed vinyl chloride; natural rubber, synthetic rubber, silicone rubber,
Various rubber sheets such as fluorinated ethylene rubber; sheets made of various metals such as steel, stainless steel, copper, and aluminum; glass; wood, paper, cloth, and the like can be used, and are not particularly limited.

The shape of the substrate is not particularly limited, and may be any shape such as a sheet, a prism, a rod, a sphere, and an aspheric surface, and may be a foam.
In the curable pressure-sensitive adhesive sheet, the thickness of the pressure-sensitive adhesive layer is not particularly limited, but is preferably about 0.5 to 4 mm, more preferably 0.8 to 3 m.
m.

(Adhesion) The curable pressure-sensitive adhesive sheet manufactured as described above is usually stored as a laminate in which a release sheet is bonded to the surface of the pressure-sensitive adhesive layer.

According to the bonding method of the present invention, the release sheet on the curable adhesive sheet stored as described above is peeled off, and when the adhesive sheet is attached to a member to be joined, 300 μm is applied to the curable adhesive sheet. Irradiate light with a wavelength of ｎｍ370 nm. That is, before applying to a member to be joined, a method in which light is applied to the surface of the adhesive layer exposed by peeling the release sheet and then attached to the member to be joined, or a curable adhesive sheet Is applied to the member to be joined, and then the curable adhesive sheet is irradiated with light. In the latter method, after the curable adhesive sheet is attached to the member to be joined, the release sheet on the back side of the curable adhesive sheet is peeled off, and the newly exposed adhesive layer surface is irradiated with light. Alternatively, if the member to be joined is transparent, light may be emitted from the member to be joined.

Light irradiation is performed to activate the photocationic polymerization initiator, and light having a wavelength of 300 to 370 nm is used. If it is less than 300 nm, sufficient adhesive strength may not be obtained due to uncuring inside, and if it exceeds 370 nm, the curable adhesive sheet becomes difficult to absorb sufficient light energy and may not be cured.

Further, the irradiation intensity of the light irradiated upon curing is desirably 5 mW / cm ² or more. If it is less than 5 mW / cm ² , the cationic photopolymerization initiator may not be sufficiently activated, and the curing may not proceed sufficiently.

Preferably, after the light irradiation, the curing is carried out in such a manner that the progress of the curing in the dark reaction is in the range of 50 to 100% of the conversion of the epoxy group after 7 days at 25 ° C. If the epoxy group conversion is less than 50%, sufficient adhesive strength may not be obtained.

The epoxy conversion is measured in the following manner. (Epoxy group conversion) The content of epoxy group was determined by adding hydrochloric acid-
It can be determined by a method called the dioxane method. That is, to a predetermined amount of the curable adhesive sheet, a hydrogen chloride dioxane solution and ethanol are added at a ratio of 1: 1 and the mixture is stirred at room temperature for about 5 hours, and the unreacted hydrogen chloride is reversed with potassium hydroxide. Perform a titration. Epoxy group content Z (m
ol / g) is calculated as follows.

Z (mol / g) = (S ₁ -S ₂ ) × C ×
f / (W _s × 1000) S ₁ (mL): Titration of potassium hydroxide in ethanol solution required for this test S ₂ (mL): Titration of potassium hydroxide in ethanol solution required for blank test C ( mol / L): Concentration of potassium hydroxide in ethanol solution used for titration f: Factor of potassium hydroxide in ethanol solution used for titration W _S (c): Collection amount of titration sample However, carboxyl group etc. When the acid is present, the concentration of the acid is determined in advance, and the value obtained by subtracting the value from Z is the epoxy group content.

The conversion of the above epoxy group (Conv
(%)) Was determined by the following equation. Conv (%) = (Z ₀ −Z ₁ ) / Z ₀ × 100 Z ₀ (mol / g): Epoxy group content of the curable adhesive sheet before light irradiation Z ₁ (mol / g): The epoxy group content of the curable pressure-sensitive adhesive sheet for a certain time after light irradiation, wherein Z ₀ and Z ₁ are determined by the hydrochloric acid-dioxane method described above.

(Vibration Suppression Structure) In the vibration suppression structure according to the second aspect of the present invention, the first member and the second member are joined via the curable adhesive sheet. It is characterized by being.

That is, according to the above-mentioned bonding method, the first
By adhering the second member and the second member via the curable adhesive sheet, the vibration damping structure according to the second aspect of the present invention can be obtained. In this case, the materials of the first and second members to be joined are not particularly limited, and are arbitrary such as metal, synthetic resin, rubber, and wood.

(Function) In the bonding method according to the first aspect of the present invention, since the curable pressure-sensitive adhesive sheet has tackiness, it can be bonded to a member to be bonded made of a non-heat-resistant material or another material. Can be easily attached and 300 ~
Irradiation with light having a wavelength of 370 nm activates the cationic photopolymerization initiator, and the ring-opening polymerization of the compound having an epoxy group proceeds to cure. Since this curing does not proceed rapidly, the curing type adhesive sheet can be easily and securely attached to the adherend using the adhesive force of the curing type adhesive sheet even after light irradiation. Can be matched. Therefore,
Does not require temporary fixing.

Furthermore, since the curing is performed by light irradiation, even when joining members having low heat resistance, deformation of the members to be joined hardly occurs. In addition, although curing proceeds by light irradiation, since it is not necessary to continue light irradiation until curing is completed, it can be used for joining members having no light transmittance or joining in a shadow zone.

Further, when the curing of the curable pressure-sensitive adhesive sheet is completed, the members joined through the curable pressure-sensitive adhesive sheet are firmly joined. Has moderate flexibility and exhibits excellent vibration damping and soundproofing effects.

In the vibration damping structure according to the second aspect of the invention, the first and second members are joined via the curable adhesive sheet, and the curable adhesive sheet is Since it has sufficient elasticity after completion of curing, propagation of vibration between the first and second members can be suppressed. Therefore,
A structure excellent in vibration damping and soundproofing effects can be obtained.

[0055]

The present invention will be clarified below by describing non-limiting examples of the present invention.

Example 1 In a 2 L separable flask, 5 parts by weight of n-butyl acrylate, 25 parts by weight of glycidyl methacrylate, and 75 parts by weight of an epoxy resin (trade name: Epicoat 828, manufactured by Yuka Shell Epoxy Co., Ltd.) Parts, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide (Ciba Geigy, trade name: Irgacure 1700) as a photoradical polymerization initiator, and a photocation Polymerization initiator (manufactured by Asahi Denka Kogyo KK, trade name: Optomer SP-17)
0) 0.5 parts by weight with stirring until homogeneous, and then dissolved oxygen was removed by bubbling with nitrogen gas for 20 minutes to obtain a photopolymerizable composition.

The above photopolymerizable composition was treated with a polyethylene terephthalate film (hereinafter referred to as PE
T film) so as to have a thickness of 1.0 mm.
An ET film was coated to obtain a laminated film. Using a fluorescent lamp having a maximum emission wavelength at 400 nm and near-ultraviolet light substantially not containing light in a wavelength range of 370 nm or less, the laminated film thus obtained was irradiated with near-ultraviolet light having a light intensity of 1 nm.
Irradiation was performed for 5 minutes so that the pressure became mW / cm ² , thereby obtaining an adhesive sheet sandwiched between PET films.

Next, one of the PET films was peeled off, and a glass cloth having a thickness of 0.1 mm was adhered thereto to form a curable adhesive sheet (1.0 mm × 50 mm × thickness).
150 mm).

In the above-mentioned curable pressure-sensitive adhesive sheet, the PET film laminated on the opposite surface of the glass cloth is peeled off so that light of 300 nm or more and less than 350 nm has a light intensity of 0.05 mW / cm ² or more. For 30 seconds, interposed between the first and second members made of 0.8 mm thick × 50 mm × 120 mm cold-rolled steel plates, so that the first and second hardened adhesive sheets have a thickness of 1 mm. The vibration damping structure was obtained by pressing the member 2 in the thickness direction.

Example 2 20 parts by weight of 2-ethylhexyl acrylate and 15 parts by weight of N-vinylpyrrolidone were used as monomer components for obtaining an acrylic polymer, and an epoxy resin (oil) was used as a compound having an epoxy group. Curable adhesive sheet was obtained in the same manner as in Example 1 except that 65 parts by weight of trade name: Epicoat 828, manufactured by Kasei Shell Epoxy Co., Ltd. were used. A structure was obtained.

Comparative Example 1 100 parts by weight of an epoxy resin (trade name: Epicoat 828, manufactured by Yuka Shell Epoxy Co., Ltd.), 5 parts by weight of dicyandiamide, and 2,4-diamino-6 [2'-methyl] as an imidazole compound Imidazole (1) ′] ethyl-s-triazine isocyanuric acid adduct (2 parts by weight) was mixed and mixed with two rolls to obtain an epoxy resin composition.

The above epoxy resin composition was rolled into a sheet so as to have a thickness of 1.0 mm using a press machine to obtain an adhesive sheet. 0.8 mm thick using this adhesive sheet
First and second cold-rolled steel sheets of × 50 mm × 120 mm
Between the members and pressure bonded, the thickness of the adhesive sheet is 1mm
And bonded together. Thereafter, heat curing was performed at 180 ° C. for 30 minutes to obtain a test piece.

(Measurement of Vibration Suppression Effect) In general, a loss factor is used as an index representing the vibration suppression and sound insulation effects of a material.
η is used, and a material having η of 0.05 or more is considered to be suitable for vibration damping and soundproofing. Many vibration damping and soundproofing materials have been proposed. As a measuring method, two cold-rolled steel sheets (0.8 mm thick, 50 mm × 120 mm) are alternately stuck to each other, leaving one end at 2 cm, and sandwiching the adhesive layer so as to have a thickness of 1 mm. Form a layer. One end of the sample steel plate thus obtained is fixed, a pickup sensor is mounted on the upper surface of the center of the sample, and the loss coefficient (η) is obtained from the attenuation of vibration when the other end is hit with a hammer. .

(Measurement of Room Temperature T Peeling Force and Room Temperature Shearing Force) In the measurement of room temperature T peeling force and room temperature shearing force, an adherend was attached to a light post-curing adhesive sheet and a post-curing adhesive sheet. After combining, after curing at 25 ° C for 7 days, JISZ 023
7 was measured.

The results are shown in Table 1 below.

[0066]

[Table 1]

As is clear from Table 1, in each of Examples 1 and 2, and Comparative Example 1, the loss coefficient was higher than that of the case of using the cold-rolled steel sheet alone, and it was found that the cold-rolled steel sheet had a vibration damping and soundproofing effect. In addition, it can be seen that the loss coefficients of Examples 1 and 2 are higher than those of Comparative Example 1, and therefore, it is possible to exhibit more excellent vibration damping and soundproofing effects.

In addition, the vibration-damping structures obtained in Examples 1 and 2 were superior to the test piece of Comparative Example 1 in the shear adhesive force and the T peeling force. It can be seen that not only is the soundproofing effect excellent, but also the adhesive strength between the members can be effectively increased.

[0069]

According to the joining method of the present invention, since the curable adhesive sheet contains an acrylic polymer as a main component, it can be easily attached to a member to be joined by its adhesive strength. Curing proceeds by irradiation with light having a wavelength of 300 to 370 nm, but does not proceed rapidly, so that a curable adhesive sheet can be easily attached to a member to be joined using the adhesive force of an acrylic polymer. can do.

In addition, since it is adhered by the above-mentioned adhesive strength, it is not necessary to carry out work such as temporary fixing and pressing after attaching. In addition, curing is promoted by irradiating light before or after attaching the curable adhesive sheet to a member to be joined. In other words, since curing is performed using light, deformation of a non-heat-resistant material is less likely to occur than in a conventional thermosetting adhesive sheet. In addition, the curable adhesive sheet before light irradiation has excellent storage stability because the curing reaction does not proceed even when exposed to a high temperature.

Further, since heat energy is not required for curing, energy cost can be reduced. Further, after light irradiation, the ring-opening polymerization of the compound having an epoxy group proceeds, and when the curing is completed, the members to be joined are firmly adhered to each other via the curable adhesive sheet. And the members can be joined with the same high adhesive strength as in the case of welding.

Furthermore, not only is the adhesive strength excellent,
The vibration damping structure according to the second aspect of the present invention, in which the first and second members are joined via the curable adhesive sheet, exhibits excellent vibration damping and soundproofing effects.

Therefore, according to the vibration damping joining method according to the first aspect of the present invention, not only can the productivity at the time of joining various members be increased, but also a material having insufficient heat resistance or a weak mechanical strength. The present invention can be applied to the joining of members made of a thin plate-like material and the like, and the joined portions can have excellent vibration damping and soundproofing effects.

Therefore, the vibration damping joining method according to the first aspect of the present invention and the vibration damping structure according to the second aspect of the present invention can be applied to home appliances with vibration such as refrigerators, air conditioners, and washing machines, The present invention can be suitably used for electronic devices with built-in motor-driven vibration such as CD players.

Claims (2)

[Claims] 1. A curable pressure-sensitive adhesive sheet comprising a composition containing an acrylic polymer, a compound having an epoxy group, and a cationic photopolymerization initiator, which is cured by irradiating light, is prepared and joined. A vibration damping bonding method, comprising: irradiating the curable adhesive sheet with light having a wavelength of 300 to 370 nm when joining members to be bonded via the curable adhesive sheet. 2. A method according to claim 1, wherein the first member and the second member each include an acrylic polymer, a compound having an epoxy group, and a cationic photopolymerization initiator, wherein the composition is cured by light irradiation. A vibration damping structure, wherein the vibration damping structure is joined via a cured curable adhesive sheet.