JPH01297452A - Epoxy resin composition - Google Patents

Abstract

PURPOSE:To obtain the title composition good in handleability and outstanding in bond strength by incorporating an epoxy resin with composite fine granules made up of a flexible polymer and a cured epoxy resin. CONSTITUTION:The objective composition can be obtained by incorporating (A) 100 pts.wt. of an epoxy composition with (B) 3-100 (pref. 5-50) pts.wt. of spherical fine granules <=100 (pref. <=30)mum in mean size, either (1) made up of B1: the surface layer consisting of a cured epoxy resin from an epoxy compound having in one molecule two or more epoxy groups and an epoxy curing agent and B2: the interior consisting of a polymer <=20 deg.C in glass transition temperature and >=5,000 in number-average molecular weight (e.g., isoprene rubber) or (2) a phase-separated mixture comprising the components B1 and B2 with the latter representing a continuous layer. (The amount of the component B is calculated as the component B2 polymer).

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an epoxy resin composition containing composite fine particles consisting of a flexible polymer and a cured epoxy resin.

[Prior Art] Epoxy resins are used in a wide range of industrial fields as paints, adhesives, and molding materials because of their excellent mechanical, thermal, electrical, and adhesive properties. On the other hand, it is hard and brittle and generates internal stress as it hardens and cools, so when used as an adhesive, it has problems such as low peel strength and, in the case of molded products, cracks are likely to occur.

In order to solve these problems, various studies have been carried out in the past. The most common method is known as rubber blend modification. Specifically, molecule 1 is 3,00
0 or so liquid rubber, especially liquid butadiene-acrylonitrile copolymer (CTBN) having terminal or pendant carboxyl groups is often used.

Furthermore, in JP-A No. 62-22850, fine polymer particles are prepared by coating the surface of a polymer whose glass transition temperature is below room temperature with a polymer whose glass transition temperature is above room temperature by an emulsion polymerization method, and are made into powder. A method has been proposed in which the cured epoxy resin is blended with the epoxy resin after recovery to reduce the internal stress of the cured epoxy resin.

[Problems to be Solved by the Invention] However, carboxyl group-containing liquid rubbers have low compatibility with epoxy resins, especially epoxy resins with large molecular weights, and furthermore, when cured, the particle size of the rubber component particles forming the dispersed layer may be reduced. Since it is difficult to control, there is a problem in that it is difficult to always obtain a uniformly cured resin.

Furthermore, in the technique of JP-A-62-22850, since an acrylic polymer component having a relatively high glass transition temperature is interposed between the epoxy resin of the matrix and the acrylic polymer having a glass transition temperature below room temperature, There is a problem that the reinforcing effect of the particles is low, and in some cases, the particles penetrate into the epoxy resin layer and deteriorate the properties of the epoxy resin matrix. Furthermore, there was a problem in that the licking operation of repeating polymerization was complicated.

The present invention aims to solve such problems,
Without sacrificing the original excellent properties of epoxy resin,
The object of the present invention is to provide an epoxy resin composition that has reduced internal stress, improved peel adhesive strength, and further improved shear adhesive strength and impact adhesive strength.

[Means for Solving the Problems] In order to achieve the above object, the present invention has the following configuration.

"An epoxy resin composition comprising particles A below substantially dispersed in an epoxy resin.

Particle A: The inside and the surface layer covering it are separated, and the surface layer is as below (a) and the inside is as below (b), or the following (b) is a continuous layer, (a) and ( Spherical fine particles with an average particle diameter of 100 μm or less, which are a phase-separated mixture with

(A): A cured epoxy resin consisting of an epoxy compound having at least two epoxy groups in one molecule and an epoxy curing agent.

(b) A polymer having a glass transition temperature of 20°C or less.

As the epoxy compound in the cured epoxy resin (a) of the present invention, epoxy resins having at least two epoxy groups in the molecule are widely used, and specifically, bisenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol F type epoxy resin, Bisphenol S type epoxy resin, phenol novolac epoxy resin, cresol novolac epoxy resin, glycidyl ether type epoxy resin such as triglycidyl ether triphenylmethane, tetraglycidyl ether tetraphenylethane, hexahydrophthalic acid glycidyl ester, dimer acid glycidyl ester, etc. Glycidyl ester type epoxy resin, triglycidyl-P-
Examples include, but are not limited to, glycidylamine type epoxy resins and alicyclic epoxy resins such as aminophenol, tetraglycidyl aminodiphenylmethane, tetraglycidyl metaxylene diamine, and triglycidyl isocyanurate.

In addition, as the epoxy curing agent used as the curing agent for the epoxy resin, those that are sparingly soluble in water are preferably used, and specifically, polyamide amines, alicyclic polyamines, aromatic polyamines, polyphenols, tertiary polyamines, etc. Examples include amines, imidazoles, and acid anhydrides.

The amount of these epoxy curing agents is preferably in the range of 0.8 to 1.2 equivalents per equivalent of the epoxy group of the epoxy compound, and in the case of a catalyst type curing agent, the epoxy compound
It is preferable to use approximately 20 parts by weight or less relative to 0 parts by weight.

The combination of the epoxy resin and the epoxy curing agent in the particles A is not particularly limited, but it is preferable to use the same combination as in the epoxy resin composition in which the particles A are dispersed.

In the present invention, "substantially dispersing the particles A in the epoxy resin" means that each particle is independently dispersed in the epoxy resin serving as a matrix without agglomeration of the particles A. .

The inside of the particle (A) of the present invention is made of a polymer having a glass transition temperature of 20°C or less (b), or (b)
It consists of a phase-separated mixture of (a) and (b) with a continuous layer, but the polymer with a glass transition temperature of 20°C or less that constitutes (b) has a number average molecular weight of 5,000 or more. It is preferably 10,000 or more, and more preferably 10,000 or more.

In addition, in order to form a phase i4 structure within the particles, 1δE-δR1 is 0.6 or more, where δF is the solubility parameter of the epoxy compound and δR is the solubility parameter of the polymer whose glass transition temperature is 20°C or lower. It is preferable that it is, and further, it is preferable that it is 1.0 or more. Polymers that satisfy these characteristics include isoprene rubber, butadiene rubber, butyl rubber, nitrile rubber, and styrene rubber.
Examples include butadiene rubber, epichlorohydrin rubber, acrylic rubber, and hydrogenated products or derivatives thereof. Among these polymers, carboxyl groups,
A polymer into which at least one functional group selected from an acid anhydride group, an epoxy group (including a glycidyl group), an amine group, and a hydroxyl group is introduced is partially bonded to the epoxy compound at the phase separation interface during curing of the epoxy compound. can react or have the same curing behavior, improving adhesion at phase separation interfaces,
That is, it is particularly preferable because the properties of the epoxy resin composition in which the particles are finally dispersed can be further improved. In the present invention, the polymer may be a homopolymer or a copolymer, or two or more types of polymers may be used in combination.

In the present invention, a polymer having a glass transition temperature of 20°C or less (
The composition ratio of b) in the spherical fine particles is preferably 90 wt% or less. If it exceeds 90 wt%, the surface of the fine particles cannot be sufficiently covered with the cured epoxy resin, which may cause blocking during handling.

Next, a method for producing spherical fine particles of the present invention will be explained.

In the present invention, it is preferable that the epoxy compound (a), the epoxy curing agent, and the copolymer (b) having a glass transition temperature of 20° C. or less can temporarily form a transparent compatible solution. If a compatible solution cannot be formed, a difference in composition ratio will occur between the fine particles obtained by the manufacturing method described below, and for example, fine particles containing only the polymer (b) may be produced, which is not preferable. The epoxy compound (a) and epoxy curing agent, which are liquid or solid at room temperature, and (
There is a heating melt kneading method as a method for compatibilizing the polymer (b), but the curing reaction between the epoxy compound and the epoxy curing agent progresses during heating, which may make it difficult to form spherical particles.

In consideration of the above points, in the present invention, a method of temporarily forming a compatible solution by dissolving each component using a common solvent is preferably used. A method for forming the thus formed compatible solution into spherical fine particles includes a method in which the compatible solution is suspended or dispersed in a liquid mainly consisting of water. Typical methods will be listed below, but the present invention is not particularly limited to these methods.

(2) A method in which the compatible solution is continuously ejected from a nozzle that vibrates in the air or in the liquid, cutting it into droplets and collecting them in the liquid.

(2) A method in which the compatible solution is ejected in pulses from a nozzle in the air or in the liquid, and then collected in the liquid.

(2) A method of emulsifying the compatible solution using an emulsifier.

Among the above methods, method (2) is preferably used in the present invention from the viewpoint of productivity.

The organic solvent suitable for the above-mentioned spherical microparticle formation method is preferably one that is substantially sparingly soluble in water and has a boiling point of less than 100°C. Specifically, hydrocarbons such as benzene and cycloxane, halogenated hydrocarbons such as dichloromethane, chloroform, carbon tetrachloride, dichloroethane, trichloroethane, and trichloroethylene, esters such as ethyl acetate, and ketones such as methyl ethyl ketone are listed. and two or more types may be mixed and used. Furthermore, in order to further improve the solubility of each component, it is also possible to use an appropriate amount of an organic solvent that is miscible with water.

In the above-mentioned spherical micronization method, the organic solvent used is 6
If 0% by weight or more is insoluble in water, the operation can be carried out without any problem.

Next, the organic solvent in the compatible solution droplets in the suspension is volatilized and removed by heating and/or reduced pressure. By removing the organic solvent, a phase-separated structure of the epoxy compound and the polymer (iii) may be formed in the particles.

Finally, heat curing treatment is performed under normal pressure or pressurization to cause the epoxy compound in the particles to react with the epoxy curing agent, and then water is removed by filtration or centrifugation.
Wash and dry to obtain spherical fine particles. The heat curing treatment temperature is preferably 60°C or higher. During this heat curing treatment, a phase-separated structure of the epoxy compound and the polymer (iii) is finally formed.

As a result of observation with a transmission electron microscope, the spherical fine particles obtained by the method of the present invention have a structure in which the surface layer is made of a coating layer of cured epoxy resin, and the inside thereof has a glass transition temperature of 20°C or less. It was observed that the polymers formed a phase-separated structure in a continuous layer. In addition, the phase-separated state exhibits various structures such as a sea-island structure and a lotus root-like structure depending on the characteristics of the polymer (c) used, but in the present invention, if a phase-separated structure is formed, It is possible to exhibit the desired characteristics. The reason why such a structure was formed is not clear, but it was formed during the process of dispersion into a water-based dispersion medium, desolvation in the suspended liquid state, and subsequent hardening treatment. , is a highly preferred structure for achieving the present invention.

The average particle diameter of the fine particles obtained as described above was 100.
μm or less, preferably 70 μm or less, more preferably 3 μm or less
It is preferably 0 μm or less. If the average particle diameter exceeds 100 μm, it is not preferable because the handling property deteriorates during kneading with the epoxy resin as a matrix, or the physical properties of the composition are impaired due to not being finely dispersed.

Further, other components such as pigments, dyes, antioxidants, heat resistant agents, lubricants, antistatic agents, plasticizers, and other polymers can be added to the spherical fine particles of the present invention. Furthermore, it is also possible to use inorganic fillers such as titanium oxide, talc, and silica supported on the surface of the spherical fine particles of the present invention.

The epoxy resin for the matrix of the epoxy resin composition of the present invention comprising the above-mentioned spherical fine particles as a dispersed phase can be a conventionally known epoxy resin, that is, a compound having at least two epoxy groups in the molecule. . Furthermore, conventionally known compounds can be used as the curing agent. Furthermore, it is also possible to use a curing accelerator together with the curing agent. Details of these compounds are explained in detail in, for example, "New Epoxy Resin" (Shokodo), edited by Hiroshi Kakiuchi.

In the present invention, in order to obtain the desired epoxy resin composition by blending the spherical fine particles with the epoxy resin, the fine particles are thoroughly mixed with the epoxy resin using a three-roll machine, an extruder, a melt mixer, a ball mill, etc. Just mix. At this time, additives such as a curing agent, a filler, an antioxidant, a lubricant, and an antistatic agent may be added as necessary.

In the epoxy resin composition obtained as described above, the spherical fine particles are uniformly dispersed without agglomeration.

In the epoxy resin composition of the present invention, the amount of particles (A) added is 3 to 100 parts by weight as a polymer having a glass transition temperature of 20°C or less in the fine particles, based on 100 parts by weight of the matrix epoxy resin. , preferably 5 to 50 parts by weight. If it is less than 3 parts by weight, a sufficient modifying effect cannot be obtained, and if it exceeds 100 parts by weight, it becomes difficult to obtain the properties required of an epoxy resin, such as heat resistance, electrical properties, and adhesiveness.

[Example] Examples of the present invention are listed below, but the present invention is not limited thereto.

Synthesis Example 1 16 parts by weight of bisphenol A type epoxy resin (trade name [Epicote 828J, manufactured by Yuka Shell Epoxy ■), 1 part of diaminodiphenylmethane 4-fold, and butyl acrylate-ethyl acrylate-acrylonitrile-acrylic acid copolymer (number average molecular weight 300 parts by weight of ethyl acetate was added to 80 parts by weight (100,000, glass transition temperature: 10° C.) and mixed to obtain a homogeneous solution. The solution was heated at 30°C for 90°C.
300 parts by weight of an aqueous solution of 8% polyvinyl alcohol (product name: Gohsenol GL-05J manufactured by Nippon Gohsei Chemical Co., Ltd.) was continuously added over 10 minutes while stirring at the rotational speed of the Orpm to form an initial water-in-oil emulsion. Finally, an oil-in-water emulsion was obtained.The emulsion was heated to 50°C under reduced pressure while stirring at 20 Orpm to remove ethyl acetate by volatilization.Furthermore, the emulsion was placed in an autoclave equipped with a stirrer. and heated at 90℃ for 2 hours with slow stirring, followed by 1 hour.
Heat curing treatment was carried out at 50° C. for 2 hours, and after cooling to room temperature, it was taken out from the container, filtered, thoroughly washed with warm water, and dried to obtain spherical fine particles with an average particle diameter of 3.1 μm.

Figure 1 shows a transmission electron micrograph (400,000x magnification) showing the particle structure of the obtained spherical fine particles.The sample was dyed with osmic acid, and the dark areas are cured epoxy resin, and the light areas are stained with osmic acid. is a polymer having a glass transition temperature of 20°C or less. It can be seen that the epoxy resin and acrylic rubber form a phase 4 structure, and the surface layer is covered with the epoxy resin layer.

Synthesis Example 2 In Synthesis Example 1, butyl acrylate-ethyl acrylate-acrylonitrile-glycidyl methacrylate copolymer was used instead of butyl acrylate-ethyl acrylate-acrylonitrile-acrylic acid copolymer, number average molecular weight: 80,000, glass transition temperature: 15 The same operations as in Synthesis Example 1 were carried out except that spherical fine particles with an average particle diameter of 2.degree. 9 .mu.m were obtained.

FIG. 2 shows a transmission electron micrograph showing the particle structure of the obtained spherical fine particles (magnification: 400,000 times).

Examples 1 to 4 According to Table 1, the spherical fine particles obtained in Synthesis Examples 1 and 2 were mixed and dispersed in a bisphenol A type epoxy resin (trade name "Epicoat 828J" manufactured by Yuka Shell Epoxy ■), and the cured product was Don't create it.

Curing was performed at 80°C for 2 hours, then at 150°C for 2 hours, and finally at 150°C for 2 hours.
The test was carried out at 80°C for 2 hours.

Comparative Example 1.2 According to Table 1, a cured modified epoxy resin without the addition of a rubber component and a terminally carboxylated butadiene-acrylonitrile copolymer (trade name: "Hiker CTBN1300X8J," manufactured by Gudrich Co., Ltd., which is a liquid rubber) was prepared.

Curing was performed under the same conditions as in the examples.

Examples 1 to 4 produced above. For Comparative Examples 1 and 2, the adhesive strength (resistance adhesive strength, tensile shear adhesive strength, impact adhesive strength) was determined according to JIS K6854 and JIS K6854, respectively.
K6850. Measured according to JIS K6855.

The measurement results are shown in Table 2, and it was found that the epoxy resin composition of the present invention had excellent adhesive strength.

Table 1 (Unit double placement part) [Effects of the invention] The epoxy resin composition of the present invention is easy to handle and has excellent adhesive strength.

[Brief explanation of the drawing]

FIG. 1 is a photograph showing the particle structure of spherical fine particles obtained in Synthesis Example 1 of the present invention. FIG. 2 is a photograph showing the particle structure of spherical fine particles obtained in Synthesis Example 2 of the present invention. Patent applicant Toshi Co., Ltd. Figure 1: ZI! !

Claims (1)

[Claims] (1) An epoxy resin composition characterized in that the following particles A are substantially dispersed in an epoxy resin. Particle A: Consisting of an interior and a surface layer covering it, the surface layer is as shown below (a) and the inside is as shown below (b), or (a) with the following (b) as a continuous layer. (b) Spherical fine particles with an average particle diameter of 100 μm or less, which are a phase-separated mixture with (b). (A): A cured epoxy resin consisting of an epoxy compound having at least two epoxy groups in one molecule and an epoxy curing agent. (b): A polymer having a glass transition temperature of 20°C or less.