JPH0570649B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a one-component epoxy resin composition that has low viscosity and excellent storage stability, and more specifically, has excellent storage stability and has excellent heat resistance, surface smoothness, and electrical properties. The present invention relates to an epoxy resin composition capable of forming coating films and molded articles having excellent chemical resistance. [Prior Art] Trimellitic acid ester anhydride obtained from trimellitic acid anhydride and a polyfunctional alcohol is mainly used as a curing agent for general-purpose epoxy resins because it gives a cured product with excellent heat resistance. Widely used in fields where heat resistance is required. All of these trimellitic acid ester anhydrides are solid at room temperature, so when used as a curing agent for liquid epoxy resin, liquid acid anhydrides (for example, methylhexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, etc.) should be used. It is generally used by dissolving it in a soluble solvent. but,
Since mixtures of these liquid modified products and liquid epoxy resins form a uniform liquid, they inevitably suffer from short pot lives and poor storage stability. As a method to overcome these drawbacks, a liquid epoxy resin composition in which mechanically pulverized finely powdered polyhydric carboxylic acid or its anhydride is dispersed has been proposed (Japanese Patent Laid-Open No. 55-60569). . However, in general, mechanically pulverizing a solid into fine particles of 100 microns or less requires a large amount of energy, and the resulting finely pulverized material tends to stand up as dust (Japanese Patent Application No. 60-36738). It is also unfavorable from an environmental standpoint. [Problems to be Solved by the Invention] The object of the present invention is to create a liquid epoxy resin composition that has excellent heat resistance, is liquid, has excellent storage stability, and is significantly improved in terms of manufacturing work environment. With the goal. [Means for Solving the Problems] As a result of intensive studies to achieve the above object, the inventors of the present invention have solved the problem by heating and dissolving trimellitic acid ester anhydride in a specific solvent and then cooling it while stirring. A paste-like material in which spherical fine particles of anhydride are uniformly dispersed is obtained by a so-called chemical method, and an epoxy resin composition made by dispersing this paste-like material is a one-part material that can achieve the intended purpose. The present inventors have discovered that the epoxy resin composition is a polyurethane epoxy resin composition, and have completed the present invention based on this knowledge. That is, the one-component epoxy resin composition according to the present invention is obtained by precipitating and dispersing a trimellitic acid ester anhydride represented by the general formula () in a medium represented by the general formula (), and then dispersing the dispersion at room temperature. It is characterized by being blended with liquid epoxy resin.

[Chemical formula] (However, R represents an alcohol residue, and n is 2 to 4.) The above trimellitic acid ester anhydride can be used, for example, with trimellitic acid anhydride and a polyol having 2 to 4 hydroxyl groups in the molecule. (Special Publication No. 52-46940). The above-mentioned polyols preferably have 2 to 12 carbon atoms, and may be entirely aliphatic or may have an aromatic substituent therein. Among such polyols having terminal hydroxyl groups are ethylene glycol, 1,3-propanediol, 1,4-
butanediol, 1,5-pentanediol,
Aliphatic diols such as 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, neopentyl glycol, methylpropylpropanediol, Cyclic diols such as p-dihydroxymethylbenzene, cyclohexanedimethanol, and hydrogenated bisphenol A, glycol ethers such as diethylene glycol and triethylene glycol, and glycerin and trimethylolpropane having three or more hydroxyl groups. , pentaerythritol, etc. may also be used in conjunction with the diol. The medium for dispersing the acid anhydride according to the present invention has the general formula ()

[Chemical formula] (However, R ¹ and R ² are alkyl groups having 1 to 8 carbon atoms, and may be the same or different. R ³ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. One type or a mixture of two or more of the media represented by (m represents 1 to 20) is suitable, specifically cellosolve-based or carbitol-based media, such as methyl cellosolve acetate, butyl cellosolve acetate, Examples include ethyl carbitol acetate, butyl carbitol acetate, mixed media thereof, and mixed media with other organic solvents. The mixing ratio (weight ratio) of trimellitic acid ester anhydride and medium is 1:9 to 9:1, preferably 1:
The ratio is 2 to 4:1. The acid anhydride according to the present invention is heated and dissolved in a medium,
When this solution is cooled while stirring, the acid anhydride is precipitated as fine particles and uniformly dispersed in the medium to form a paste-like mixture. The particle size of the fine particles changes depending on the temperature at which the particles are precipitated, the stirring speed, etc., and since they exhibit an amorphous shape above a certain temperature, they can be controlled to a desired particle size and state. This paste is blended and dispersed in a general-purpose liquid epoxy resin. The epoxy resin recommended in the present invention may be any known epoxy resin as long as it is liquid at room temperature, and specifically, bisphenol obtained from dihydric phenols such as bisphenol A and bisphenol F and epichlorohydrin. There are type epoxy resins, alicyclic epoxy resins, glycidyl ester type epoxy resins, novolac type epoxy resins, glycidyl ether type epoxy resins of long chain polyols, polyolefin type epoxy resins, etc., and each may be used alone, or A mixture of more than one species may be used. Furthermore, the composition according to the present invention may contain conventionally known acid anhydride curing agents, curing accelerators, fillers, diluents, etc., as appropriate, as long as the desired effects are achieved. [Example] The present invention will be explained in detail with reference to Examples below. Example 1 64 g of ethylene glycol bistrimelitate dianhydride (hereinafter abbreviated as TMEG) and 64 g of diethylene glycol monoethyl ether acetate (hereinafter abbreviated as ECA) are heated and mixed at 150°C, and then cooled to 50°C. When stirring was continued for 3 hours while maintaining the temperature at 50°C, the system gradually became cloudy and a light yellowish brown TMEG paste was obtained. To this paste was added 100 g of Epicote 828 and stirred for 1 hour at room temperature, resulting in a yellow, low viscosity one-component formulation. When observed under a microscope, TMEG fine particles with a particle size distribution of 10 to 50 μm were observed. Example 2 TMEG 96g, ethylene glycol monobutyl ether acetate 20.6g and Swazol 1000
(Maruzen Oil Co., Ltd.: aromatic solvent) 20.6 g was heated and mixed at 150°C, cooled to 50°C, and stirred for 4 hours.
A paste was obtained in which spherical TMEG particles with a particle size of 10 to 50 μm were dispersed. Next, 100 g of Epicote 828 was added and stirred for 1 hour at room temperature, resulting in a pale yellow, low viscosity, one-component formulation. Example 3 100 g of glycerin tristrimeritate trianhydride (hereinafter abbreviated as TMTA) and 67 g of ECA are mixed and heated to 150°C. After the solution became a brown homogeneous solution, it was cooled to 50° C. while stirring, and stirring was continued for 3 hours to obtain a pale yellow paste. 100 g of Epicote 828 was added to this paste and stirred for 1 hour at room temperature, resulting in a yellow, low viscosity one-component formulation. Comparative Example 1 42 g of TMTA and 53 g of liquid acid anhydride (Rikashido MH-700, manufactured by Shin Nippon Chemical Co., Ltd.) were mixed and heated and stirred to 120°C to form a brown transparent liquid. Furthermore, 100 g of Epicote 828 was added and stirred at room temperature to obtain a brown transparent mixture. Comparative Example 2 A pale yellow transparent compound was obtained by mixing 86 g of liquid acid anhydride (Rikashid MH-700) and 100 g of Epicote 828 and stirring at room temperature. The physical properties of the epoxy resin compositions and cured products obtained in the above Examples and Comparative Examples are shown in the table. [Effects of the Invention] As is clear from the table, the one-component epoxy resin composition of the present invention exhibits excellent storage stability, and the cured product thereof has the characteristics of a cured product of trimellitic acid ester anhydride. It has excellent performance in certain heat resistance, electrical properties, etc. In addition, when this paste mixture is mixed with epoxy resin, it lowers the viscosity of the resin, making it easier to mix and evenly dispersing while maintaining the fine particle state. The cured product exhibits a high heat distortion temperature and has excellent heat resistance.

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Claims (1)

[Claims] 1. A trimellitic acid ester anhydride represented by the general formula () is precipitated and dispersed in a medium represented by the general formula (), and the dispersion is blended into an epoxy resin that is liquid at room temperature. A one-component epoxy resin composition. [In the formula, R ¹ and R ² are the same or different and have a carbon number of 1
~8 alkyl group. R ³ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. m represents an integer of 1 to 20. ] [In the formula, R represents an alcohol residue, and n is 2 to 4
indicates an integer. ]