JP2008133391A - Adhesive composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new adhesive composition exhibiting performances excellent in impact resistance, heat resistance, chemical resistance, water resistance, etc. <P>SOLUTION: The adhesive composition comprises an epoxydized polybutadiene, a bisphenol-based epoxy resin, a silane compound having an epoxy group and an alkoxysilane group together in the molecule and a cation polymerization initiator. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a novel adhesive composition that exhibits excellent performance in impact resistance, heat resistance, chemical resistance, water resistance, and the like.

  Epoxy adhesives have high mechanical strength and are excellent in adhesiveness, heat resistance, and chemical resistance of various substrates, and therefore are widely used from general purpose to structural adhesives. Epoxy adhesives have high heat resistance, chemical resistance, and electrical insulation, and some of them are used as adhesives for electronic materials and as adhesives for optical members.

  Epoxy adhesives can be cured from room temperature curing (used in paints and adhesives) using amino compounds such as N, N-dimethylpropylamine as curing agents, and acid anhydrides such as hexahydrophthalic anhydride as curing agents. It is possible to control a wide range of curing characteristics and various physical properties up to the high-temperature curing type (used in electrical materials), and is characterized by a wide range of applications. Furthermore, the bisphenol A diglycidyl ether type epoxy resin is preferably a cationically cured alicyclic epoxy resin or the like using an acid generator such as an iodonium salt as an initiator, so that the storage stability, pot life adjustment and the like are relatively high. It is applied to paints and adhesives that can be easily cured for a short time.

A so-called acrylic-epoxy hybrid adhesive that combines the excellent performance of an epoxy resin as an adhesive and the function of an acrylic resin as a pressure-sensitive adhesive has been proposed (see Patent Document 1). The present proposal provides a curable (meth) acrylate-modified epoxy resin composition containing an epoxy resin, a (meth) acrylate compound and a diamine compound or bis (amino) alkylpiperazine as a curing agent. According to Patent Document 1, the mechanical toughness of the epoxy resin adhesive is improved as it is, and the impact resistance is improved, and it is said that the epoxy resin adhesive is suitable for use as an adhesive for an automobile bumper or the like. The aim of this proposal is
(1) Dilute a high viscosity epoxy resin with a low viscosity (meth) acrylate and reduce the viscosity to improve the adhesive application workability.
(2) In the curing process, the epoxy resin is cured and crosslinked with the diamine compound and the like, and the polymerization of (meth) acrylate is advanced to form an epoxy-acrylic interpenetrating network structure (hereinafter also referred to as IPN). It is considered that an adhesive having excellent impact resistance is to be obtained. The aim of Patent Document 1 is very interesting. (1) When the viscosity of the adhesive is simply lowered, the adhesive viscosity becomes Newtonian, and the adhesive flows easily. There is a tendency that the thickness cannot be obtained, and there is a concern that the adhesion to the adherend will deteriorate and the adhesive strength will be insufficient. (2) As is well known, bases such as diamine compounds and bis (amino) alkylpiperazines (Meth) acrylate is extremely poorly polymerizable in the presence of a reactive compound (or N-containing atom-containing compound), and the concern remains that (meth) acrylate remains unreacted even if sufficient time is taken for curing. This is not possible, and it is predicted that the adhesive strength will vary significantly. Furthermore, (meth) acrylates are strongly anaerobic, and if deaeration (deoxygenation) is insufficient, there will be similar concerns regarding the development of adhesive strength.

  A curable adhesive containing a polyacrylate component, an epoxy component, and a cationic initiator has been proposed (see Patent Document 2).

  In the adhesive described in Patent Document 2, the polyacrylate exists independently without self-crosslinking. Accordingly, the entanglement of the epoxy with the polyacrylate, the restraint of the epoxy, and the binder force of the network structure with the epoxy are limited to some extent, and it is easily predicted that they are not so strong. In other words, it can be inferred that the IPN effect that should be originally expected is diminished only by the movement of the polyacrylate if it is dragged.

  The polyacrylate may be bonded with a specific functional group, carboxylic acid, or hydroxyl group that the epoxy and the polyacrylate have. When the functional group possessed by the polyacrylate is a carboxylic acid, a reaction with the epoxy group possessed by the epoxy resin occurs, the gelation that does not depend on the original cationic polymerization reaction of the adhesive proceeds, and the storage stability of the adhesive increases In addition to the deterioration, there is a concern that mechanical strength and adhesive strength are lowered because sufficient polymerization is inhibited. When the functional group of the polyacrylate is a hydroxyl group, when the adhesive is cured by cationic polymerization, it acts as a chain transfer agent and the apparent curing rate and cross-linking are promoted, but the degree of polymerization is reduced and the adhesive There is a concern that the material becomes brittle and does not function as a structural adhesive.

There has been proposed a photocurable resin composition that gives a cured film with excellent flexibility by irradiation with ultraviolet rays or electron beam radiation (see Patent Document 3). Patent Document 3 proposes a photocurable resin composition containing epoxidized polybutadiene, an alicyclic epoxy resin, and a photopolymerization initiator as essential components. Patent document 3 aims at improving the water resistance and adhesiveness of a photocurable resin. However, when an alicyclic epoxy resin is blended, the curability is generally excellent, but it is known that the storage stability and adhesiveness are insufficient, and this proposal is considered to be similar to that.
JP-A-63-215716 JP-T-2005-508435 JP-A-8-277320

  The present invention provides an adhesive composition that maintains and exhibits strong adhesiveness even in an electrolyte solution such as water or salt water, such as bonding of a carbon fiber reinforced plastic and an aluminum alloy.

  The present invention provides an epoxidized polybutadiene represented by the following structural formula:

(Where a + b + c = 1.0 and a + c> b, a = 0.05-0.40, b = 0.02-0.30, c = 0.20-0.80, x is 10-10 Represents an integer of 250.)
An epoxy resin represented by the following structural formula,

(However, y represents 0 or an integer of 1 to 50.)
Silane compound having both epoxy group and alkoxysilane group in the molecule represented by the following structural formula

(However, R1 and R2 are alkyl groups having 1 to 3 carbon atoms, and z is an integer of 1 to 3.)
And the adhesive composition containing a cationic polymerization initiator is provided.

  Adhesives using the adhesive composition of the present invention include metals such as iron, aluminum, copper, magnesium, titanium, and alloys thereof, polyester resins, acrylic resins, polycarbonate resins, polyphenylene sulfide resins, polypropylene alloys, polyethylene, and the like. It can be applied to a wide range of base materials such as plastics, inorganic materials such as glass, mortar and quartz.

  The adhesive using the adhesive composition of the present invention can be suitably applied particularly to plastics reinforced with carbon fiber or glass fiber. The adhesive using the adhesive composition of the present invention joins a carbon fiber reinforced plastic to a metal that is more likely to be ionic in the electrolyte solution than the carbon fiber, such as a joint between a carbon fiber reinforced plastic and an aluminum alloy. In particular, it exhibits strong adhesion, suppresses battery formation and prevents metal corrosion, and maintains and exhibits strong adhesion even in electrolyte solutions such as water and brine.

  The present invention provides an epoxidized polybutadiene represented by the following structural formula:

(Where a + b + c = 1.0 and a + c> b, a = 0.05-0.40, b = 0.02-0.30, c = 0.20-0.80, x is 10-10 Represents an integer of 250.)
An epoxy resin represented by the following structural formula,

(However, y represents 0 or an integer of 1 to 50.)
Silane compound having both epoxy group and alkoxysilane group in the molecule represented by the following structural formula

(However, R1 and R2 are alkyl groups having 1 to 3 carbon atoms, and z is an integer of 1 to 3.)
And the adhesive composition containing a cationic polymerization initiator is provided.

  Epoxidized polybutadiene represented by the following structural formula is easily produced by, for example, epoxidizing polybutadiene with hydrogen peroxide solution and peracids.

(Where a + b + c = 1.0 and a + c> b, a = 0.05-0.40, b = 0.02-0.30, c = 0.20-0.80, x is 10-10 Represents an integer of 250.)
In the adhesive composition of the present invention, the polybutadiene used as the raw material for the epoxidized polybutadiene can be arbitrarily selected from commercially available ones. For example, “Poly.BD R-15HT”, “Poly.BD R-45HT” ( Above, polybutadiene made by Idemitsu Petrochemical Co., Ltd.), “NISSO PB B-1000”, “NISSO PB B-3000”, “NISSO PB G-1000”, “NISSO PB G-3000” (above, manufactured by Nippon Soda Co., Ltd.) Polybutadiene) and the like. These polybutadienes may be used alone or as a mixture of two or more.

  In the present invention, a liquid polybutadiene represented by the following structural formula is preferably used as the polybutadiene, and an epoxidized polybutadiene obtained by epoxidizing this polybutadiene is recommended.

  As the liquid polybutadiene represented by the following structural formula,

(However, it represents an integer of a = 0.20, b = 0.20, c = 0.60, and n = 10 to 250.)
“Poly.BD R-15HT”, “Poly.BD R-45HT” (polybutadiene manufactured by Idemitsu Petrochemical Co., Ltd.) and the like are exemplified. Such a liquid polybutadiene is characterized by having a hydroxyl group in the molecule and containing more 1,4-vinyl structure than 1,2-vinyl structure. These polybutadienes may be used alone or as a mixture of two or more.

  As the epoxidized polybutadiene represented by the following structural formula obtained by epoxidizing liquid polybutadiene,

(However, a = 0.20, b = 0.20, c = 0.60, and n represents an integer of 10 to 250.)
“Epolide PB3600” (epoxidized polybutadiene manufactured by Daicel Chemical Industries) is exemplified. These epoxidized polybutadienes may be used alone or as a mixture of two or more.

  Since the epoxidized polybutadiene used in the adhesive composition of the present invention has a hydroxyl group in the molecule, an effect of increasing the curability of the adhesive is seen. In particular, in the case of thin film adhesion in which the adhesive film thickness is 100 μm or less, there is an effect of suppressing poor curing and expressing strong adhesiveness.

  At the same time, since the epoxidized polybutadiene used in the adhesive composition of the present invention has a polybutadiene skeleton having a large 1,4-vinyl structure, it is excellent in flexibility and has the impact resistance, mechanical strength, and adhesiveness of the adhesive. The effect is improved and enhanced.

  The epoxy resin represented by the following structural formula contained in the adhesive composition of the present invention is:

(However, y represents 0 or an integer of 1 to 50.)
It is a so-called bisphenol A type epoxy resin (reference: “14705 chemical product (issued in 2005)” (Chemical Industry Daily, p1126 to p1135), “Epicoat 825”, “Epicoat 827”, “Epicoat 828”, “ Examples include “Epicote 834”, “Epicote 1001”, “Epicote 1003”, “Epicote 1004” (the epoxy resin of Japan Epoxy Resin Co., Ltd.), etc. These epoxy resins may be used alone or as a mixture of two or more. May be.

  These epoxy resins have the effect of bringing a cross-linked structure to the adhesive, hardening the adhesive, and increasing the elastic modulus. It also improves adhesion and chemical resistance.

  In the adhesive composition of the present invention, when the total amount of the epoxidized polybutadiene and the epoxy resin is 100 parts by weight, the epoxidized polybutadiene is preferably 10 to 95% by weight, more preferably 20 to 90% by weight. More preferably, 20 to 80% by weight is used. When the amount of the epoxidized polybutadiene used is less than 10% by weight, the curability of the adhesive during thin film may be deteriorated. Moreover, there exists a tendency for impact resistance to deteriorate. When the amount of the epoxidized polybutadiene used exceeds 95% by weight, the viscosity of the adhesive is increased and workability may be deteriorated.

  As a silane compound represented by the following structural formula contained in the adhesive composition of the present invention,

(However, R1 and R2 are alkyl groups having 1 to 3 carbon atoms, and z is an integer of 1 to 3.)
Examples include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropyltriethoxysilane, and γ-glycidoxypropylethyldiethoxysilane. These silane compounds may be used alone or as a mixture of two or more.

  In the adhesive composition of the present invention, the silane compound preferably reacts with epoxidized polybutadiene and an epoxy resin via an epoxy group to form a crosslinked structure in the adhesive. Furthermore, for example, when the adherend is a metal such as an aluminum alloy or iron, the alkoxysilane group is oriented and reacted to form a dense polysiloxane film on the surface, making the metal nonconductive, It has the effect of preventing adhesion failure due to electrical corrosion of metals.

This function is prominent when the adherend is bonded to carbon fiber reinforced plastic (conductive plastic), aluminum alloy, iron, etc., and suppresses the generation of batteries between adherends, and is water and salt resistant. There is a tendency to dramatically improve the environmental resistance performance. This function is a function that can never be achieved even if a tough adhesive is produced by blending only epoxidized polybutadiene and epoxy resin, for example. It is achieved only when a silane compound is blended and the silane compound has both an epoxy group and an alkoxysilane group in the molecule.
In the adhesive composition of the present invention, when the total amount of epoxidized polybutadiene and epoxy resin is 100 parts by weight, the silane compound is preferably 0.5 to 100 parts by weight, more preferably 2 parts by weight. It is desirable to use 0.0 to 60 parts by weight, more preferably 5.0 to 50 parts by weight.

  When the usage-amount of a silane compound is less than 0.5 weight part, the adhesive viscosity becomes high and the tendency for handling to get a little worse is seen. Further, when the adherend is made of a metal such as a carbon fiber reinforced plastic and an aluminum alloy, there is a tendency that electric corrosion is likely to occur, water resistance and salt water resistance are deteriorated, and adhesion failure is likely to occur.

  When the amount of the silane compound used exceeds 100 parts by weight, the adhesive tends to flow with a low viscosity, and there is a tendency that a sufficient adhesive film thickness cannot be secured. As a result, it tends to cause poor curing of the adhesive and tends to cause a decrease in adhesive strength. In addition, the adhesive strength may be reduced due to the influence of low molecular weight alcohol gas generated by hydrolysis of the alkoxysilane group, or adhesion failure may occur.

  In the adhesive composition of the present invention, a cationic polymerization initiator is blended, and a curing reaction is performed by a cationic curing reaction.

  In the present invention, a sulfonium salt compound can be preferably blended as a curing agent that promotes the cationic curing reaction.

  The sulfonium salt compound is preferably a sulfonium salt compound represented by the following structural formula.

(However, R3, R4, and R5 represent an alkyl group having 1 to 12 carbon atoms.)

  Examples of the sulfonium salt compound include hexafluoroantimony salt of methylphenyldimethylsulfonium, hexafluoroantimony salt of ethylphenyldimethylsulfonium, hexafluorophosphate salt of methylphenyldimethylsulfonium, and the like. These sulfonium salt compounds may be used alone or as a mixture of two or more.

  The commercially available sulfonium salts include “Sun-Aid SI-60L”, “Sun-Aid SI-80L”, “Sun-Aid SI-100L” (product of Sanshin Chemical Industry Co., Ltd.), “UVI-6990”, “UVI-”. "6992", "UVI-6974" (product of Union Carbide), "Adekaoptomer SP-150", "Adekaoptomer SP-170", "Adeka Opton CP-66", "Adeka Opton CP-77" ( As mentioned above, Asahi Denka Kogyo Co., Ltd. product), “IRGACURE 261” (Ciba Geigy Corp. product) and the like are exemplified.

The sulfonium salt compound generates an acid by heat or light irradiation and initiates cationic polymerization of the epoxy resin.
In the present invention, those represented by the following structural formula are more preferably used as the sulfonium salt compound, and there is a tendency that the storage stability and curability of the adhesive are excellent.

(However, R3, R4, and R5 represent an alkyl group having 1 to 12 carbon atoms.)
Examples of commercially available sulfonium salts include “Sun-Aid SI-60L”, “Sun-Aid SI-80L”, and “Sun-Aid SI-100L” (product of Sanshin Chemical Industry Co., Ltd.).

  In the adhesive composition of the present invention, a curing reaction is performed by a cationic polymerization mechanism, and a tough and high adhesive strength can be produced by a quick and sharp curing reaction. Further, the storage stability of the adhesive is good, and the adhesive can be substantially made into a one-component adhesive. Handling and workability at the bonding site are improved, and bonding failures due to mixing errors can be avoided to the maximum.

  In the present invention, when the total amount of the epoxidized polybutadiene, the epoxy resin, and the silane compound is 100 parts by weight, the sulfonium salt compound is preferably 0.2 to 20 parts by weight, more preferably Is preferably used in an amount of 0.4 to 10 parts by weight, more preferably 0.5 to 8 parts by weight.

  When the usage-amount of a sulfonium salt compound is less than 0.2 weight part, the sclerosis | hardenability of an adhesive agent deteriorates and the tendency which raise | generates a hardening defect is seen. When the usage-amount of a sulfonium salt compound exceeds 20 weight part, the storage stability of an adhesive agent will be impaired and it may become impossible to manufacture a one-pack type adhesive agent. Moreover, since hardening of an adhesive progresses rapidly, the residual stress and distortion remain in an adhesive and the tendency for adhesiveness to deteriorate is seen.

  When these sulfonium salt compounds are used as curing agents, the adhesive undergoes a crosslinking reaction through a cationic polymerization mechanism and forms a crosslinked structure while mainly forming an ether bond. There is a tendency to be excellent in performance.

  The adhesive composition of the present invention is preferably cured by a cationic polymerization mechanism using a sulfonium salt compound as a curing agent. Cationic polymerization is a so-called chain transfer reaction, which has polymerization activity next to radical polymerization reaction and is characterized by sharp response to heat and light irradiation. In other words, if certain conditions are not met, the curing reaction does not occur and the adhesive is stable (good storage stability and can be made into a one-part adhesive). On the other hand, for example, at a temperature higher than a specific temperature, the curing reaction proceeds rapidly and is completed in a short time (rapid curing, reduction of unreacted substances).

  Therefore, the adhesive composition of the present invention has a pot life as compared with an adhesive using an amino compound such as polyoxypropylene-α, ω-diamine, diethylene glycol bis (3-aminopropyl) ether, diaminoguanidine as a curing agent. Is an adhesive having a long storage stability. As described, it is a one-part adhesive that does not initiate the curing reaction unless certain specific conditions are substantially met. On the other hand, under specific conditions (for example, appropriate curing temperature, ultraviolet irradiation, etc.), the curing reaction proceeds smoothly and no unreacted product remains. As a result, despite the fact that it is a one-part adhesive, a curing reaction can be performed at a relatively low temperature, and various performances such as adhesive strength, impact resistance, heat resistance, and water resistance can be achieved with a high reaction achievement rate. It will be excellent.

  In addition to cationic polymerization initiators such as epoxidized polybutadiene, silane compounds, epoxy resins, sulfonium salt compounds, the adhesive composition of the present invention includes talc, bentonite, montmorillonite, quartzite powder, glass powder, mica, potassium titanate. Reinforcing whisker, glass wool, carbon fiber, fillers for filling, and the like can be blended.

  The filler to be blended (for example, fine particle silica) imparts thixotropy to the adhesive to improve workability, or serves as a cross-linking and reinforcing point to improve adhesive strength. Since the adhesive composition of the present invention is preferably subjected to a curing reaction by a cationic reaction, a filler having a surface charge in a neutral to acidic region is recommended as a blended filler. As the filler, one having a pH of about 3 to 6 is recommended.

The adhesive composition of the present invention can be applied to an adherend in a liquid state and cured by heating to obtain an adhesive article. Moreover, after apply | coating on the protective film which can peel an adhesive agent, Preferably, it heats at suitable temperature, Preferably it is suitable time for 60 to 120 degreeC, Preferably, it is 30 seconds-10 minutes, After passing B stage Then, after pressure-bonding this to an adherend, it can be heat-cured to obtain an adhesive article.
Adhesives using the adhesive composition of the present invention are used as (structure) adhesives for automobiles, motorcycles and bicycle parts, as leisure adhesives for golf clubs, fishing rods, etc., and as structural adhesives for ships and aircraft. In addition, the present invention is suitably applied to applications requiring chemical strength such as adhesive strength, adhesive mechanical properties, toughness, and water resistance.

  Hereinafter, the present invention will be described in detail with examples.

In the examples and comparative examples, the composition ratio represents a weight ratio unless otherwise specified. The adhesion test was performed according to the following.
(1) Initial adhesion test a) Preparation of test piece Adhesive agent was uniformly applied to an aluminum plate (film thickness 50 μm, application area 25 mm × 25 mm), and another aluminum plate was pressure-bonded to the adhesive surface. If not, it was cured by heating at 120 ° C. for 1 hour. The shear adhesion force was measured using this test piece.
b) Test method A-2017P aluminum plate (size: length 50 mm, width 25 mm, thickness 2 mm) is used, and conforms to JIS K 6850 (1999) (Test method for tensile shear bond strength of rigid substrates). I went. The pulling speed is 1.0 mm / min. The test temperature was 23 ° C. unless otherwise specified.
(2) Water resistance test (1) -1) The test piece prepared in (a) was immersed in warm water at 80 ° C. for 72 hours. Then, the adhesiveness test was done according to (1) -1) (b).

Example 1
"JER 828" (Japan Epoxy Resin bisphenol A type epoxy resin) 800g, "Epolide PB-3600" (Daicel Chemical Industries epoxidized butadiene) 200g (epoxy resin / epoxidized polybutadiene = 80 / 20), 10 g of “Aerosil 380” (silica fine particles of Nippon Aerosil Co., Ltd.) were charged and stirred for 60 minutes.

  200 g of γ-glycidoxypropyltrimethoxysilane (silane compound) ((epoxy resin + epoxidized polybutadiene) / silane compound = 100/20) was charged and stirred and mixed until uniform.

To this was added 2 phr of “Sun-Aid 80L” (a sulfonium salt cation curing catalyst manufactured by Sanshin Chemical Industry), and stirring was continued for 30 minutes to produce an adhesive (1).
(Adhesive tensile test)
The adhesive (1) was spread out in a sheet shape so as to have a film thickness of 2 mm, and was cured by heating at 120 ° C. for 1 hour. This cured adhesive film was cut with a No. 3 dumbbell and subjected to a tensile test. The test results are shown in Table 1.
(Adhesive evaluation)
(1) Evaluation of initial adhesive strength Adhesive (1) was evenly applied to an aluminum plate (film thickness 50 μm, application area 25 mm × 25 mm), and another aluminum plate was pressure-bonded to the adhesive surface, and 1 at 120 ° C. Heat cured for hours. The shear adhesion force was measured using this test piece.
(2) Evaluation of adhesive strength after water resistance test The test piece prepared in (1) was immersed in warm water at 80 ° C. for 72 hours. Thereafter, an adhesion test was conducted in the same manner as (1). The adhesion test results are shown in Table 1.

Example 2
"JER 828" (bisphenol A type epoxy resin from Japan Epoxy Resin Co., Ltd.) 600g, 400g (epoxide butadiene from Daicel Chemical Industries) (epoxy resin / epoxidized polybutadiene = 60 / 40) and 10 g of “Aerosil 380” (silica fine particles of Nippon Aerosil Co., Ltd.) were added and stirred for 60 minutes.

  200 g of γ-glycidoxypropyltrimethoxysilane (silane compound) ((epoxy resin + epoxidized polybutadiene) / silane compound = 100/20) was charged and stirred and mixed until uniform.

  To this was added 2 phr of “Sun Aid 80L” (a sulfonium salt cation curing catalyst manufactured by Sanshin Chemical Industries), and stirring was continued for 30 minutes to produce an adhesive (2).

(Adhesive tensile test)
The adhesive (2) was spread in a sheet shape so as to have a film thickness of 2 mm, and was heated and cured at 120 ° C. for 1 hour. This cured adhesive film was cut with a No. 3 dumbbell and subjected to a tensile test. The test results are shown in Table 1.

(Adhesive evaluation)
(1) Evaluation of initial adhesive strength Adhesive agent (2) was uniformly applied to an aluminum plate (film thickness 50 μm, application area 25 mm × 25 mm), and another aluminum plate was pressure-bonded to the adhesive surface, and 1 at 120 ° C. Heat cured for hours. The shear adhesion force was measured using this test piece.

(2) Evaluation of adhesive strength after water resistance test The test piece prepared in (1) was immersed in warm water at 80 ° C. for 72 hours. Thereafter, an adhesion test was conducted in the same manner as (1). The adhesion test results are shown in Table 1.

Example 3
"JER 828" (Japan Epoxy Resin bisphenol A type epoxy resin) 400g, "Epolide PB-3600" (Daicel Chemical Industries epoxidized butadiene) 600g (epoxy resin / epoxidized polybutadiene = 40 / 60) and 10 g of “Aerosil 380” (silica fine particles of Nippon Aerosil Co., Ltd.) were added and stirred for 60 minutes.

  200 g of γ-glycidoxypropyltrimethoxysilane (silane compound) ((epoxy resin + epoxidized polybutadiene) / silane compound = 100/20) was charged and stirred and mixed until uniform.

  To this was added 2 phr of “Sun Aid 80L” (a sulfonium salt cationic curing catalyst manufactured by Sanshin Chemical Industry), and stirring was continued for 30 minutes to produce an adhesive (3).

(Adhesive tensile test)
The adhesive (3) was spread in a sheet shape so that the film thickness was 2 mm, and was heat-cured at 120 ° C. for 1 hour. This cured adhesive film was cut with a No. 3 dumbbell and subjected to a tensile test. The test results are shown in Table 1.
(Adhesive evaluation)
(1) Evaluation of initial adhesive strength Adhesive (3) was evenly applied to an aluminum plate (film thickness 50 μm, application area 25 mm × 25 mm), and another aluminum plate was pressure-bonded to the adhesive surface, and 1 at 120 ° C. Heat cured for hours. The shear adhesion force was measured using this test piece.
(2) Evaluation of adhesive strength after water resistance test The test piece prepared in (1) was immersed in warm water at 80 ° C. for 72 hours. Thereafter, an adhesion test was conducted in the same manner as (1). The adhesion test results are shown in Table 1.

Comparative Example 1
"JER 828" (Japan epoxy resin bisphenol A type epoxy resin) 1000g, γ-glycidoxypropyltrimethoxysilane (silane compound) 200g (epoxy resin / silane compound = 100/20), 20 g of “Aerosil 380” (silica fine particles of Nippon Aerosil Co., Ltd.) was charged and stirred for 60 minutes.

  To this was added 2 phr of “Sun Aid 80L” (a sulfonium salt cation curing catalyst manufactured by Sanshin Chemical Industry), and stirring was continued for 30 minutes to produce an adhesive (4) containing no epoxidized polybutadiene.

(Adhesive tensile test)
The adhesive (4) was spread out in a sheet shape so as to have a film thickness of 2 mm, and was heated and cured at 120 ° C. for 1 hour. This cured adhesive film was cut with a No. 3 dumbbell and subjected to a tensile test. The test results are shown in Table 2.

(Adhesive evaluation)
(1) Evaluation of initial adhesive strength Adhesive (4) was uniformly applied to an aluminum plate (film thickness 50 μm, application area 25 mm × 25 mm), and another aluminum plate was pressure-bonded to the adhesive surface, and the temperature was 1 The adhesive was not cured after heating for a period of time.

Comparative Example 2
"JER 828" (bisphenol A type epoxy resin from Japan Epoxy Resin Co., Ltd.) 600g, 400g (epoxide butadiene from Daicel Chemical Industries) (epoxy resin / epoxidized polybutadiene = 60 / 40) and 20 g of “Aerosil 380” (silica fine particles of Nippon Aerosil Co., Ltd.) were added and stirred for 60 minutes.

  200 g of phenyltrimethoxysilane was charged and stirred and mixed until uniform.

  To this was added 2 phr of “Sun-Aid 80L” (a sulfonium salt cation curing catalyst manufactured by Sanshin Chemical Industry), and the mixture was further stirred for 30 minutes to contain a silane compound having no epoxy group in the molecule. (5) was produced.

(Adhesive tensile test)
The adhesive (5) was spread out in a sheet shape so as to have a film thickness of 2 mm, and was heated and cured at 120 ° C. for 1 hour. This cured adhesive film was cut with a No. 3 dumbbell and subjected to a tensile test. The test results are shown in Table 1.

(Adhesive evaluation)
(1) Evaluation of initial adhesive force Adhesive (5) was uniformly applied to an aluminum plate (film thickness 50 μm, application area 25 mm × 25 mm), and another aluminum plate was pressure-bonded to the adhesive surface, and the temperature was 1 at 120 ° C. Heat cured for hours. The shear adhesion force was measured using this test piece.

(2) Evaluation of adhesive strength after water resistance test The test piece prepared in (1) was immersed in warm water at 80 ° C. for 72 hours. Thereafter, an adhesion test was conducted in the same manner as (1). The adhesion test results are shown in Table 2.

Claims (2)

Epoxidized polybutadiene represented by the following structural formula,

(Where a + b + c = 1.0 and a + c> b, a = 0.05-0.40, b = 0.02-0.30, c = 0.20-0.80, x is 10-10 Represents an integer of 250.)
An epoxy resin represented by the following structural formula,

(However, y represents 0 or an integer of 1 to 50.)
Silane compound having both epoxy group and alkoxysilane group in the molecule represented by the following structural formula

(However, R1 and R2 are alkyl groups having 1 to 3 carbon atoms, and z is an integer of 1 to 3.)
And an adhesive composition comprising a cationic polymerization initiator.   The adhesive composition according to claim 1, wherein the cationic polymerization initiator is a sulfonium salt compound.