JPH0372651B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an epoxy resin composition suitable for lamination, casting, impregnation, painting, etc. used in the electrical and electronic industry fields, and more specifically, it has a relatively pot life even at high temperatures. The present invention relates to a solvent-free flame-retardant epoxy resin composition that has a long dispersion stability and provides a uniform cured product. Epoxy resins are widely used in the electrical and electronic fields because they have excellent properties such as mechanical properties, electrical properties, thermal properties, chemical resistance, and adhesive properties. In the electrical and electronic fields, in recent years, varnishes have been made flame retardant to prevent fires during use, and solvent-free varnishes have been developed to improve working environments, solve pollution problems, and save resources. has become a major issue. The present invention provides a solvent-free flame-retardant epoxy resin composition that solves the above problems. That is, the present invention provides a mixture of an epoxy resin (A) that is liquid at room temperature and a compound (B) having at least two phenolic hydroxyl groups in the molecule, the epoxy resin (A) and the compound (B) ), and the compound (B) contains a bromine-containing compound in either or both of them, and the phenolic hydroxyl group is in the range of 0.05 to 0.5 per epoxy group of the epoxy resin (A). The specific gravity at 25℃ is 1.33 to 1.52.
The present invention relates to an epoxy resin composition containing 1 to 5 parts by weight of dicyandiamide powder having an average particle size of 50 μm or less per 100 parts by weight of a mixture that is liquid at normal temperature within the range of 1 to 5 parts by weight. Epoxy resin that is liquid at room temperature used in the present invention
(A) is 2,2-bis(4-hydroxyphenyl)
Bisphenol A), bis(4-hydroxyphenyl)methane (hereinafter referred to as bisphenol F), bis(4-hydroxyphenyl)methane (hereinafter referred to as bisphenol F),
), bis(4-hydroxyphenyl) such as 1,1-bis(4-hydroxyphenyl)ethane
Diglycidyl ethers of alkanes, polyglycidyl ethers of polyhydric phenols such as phenol novolak and chrysol novolak, polyglycidyl ethers of aliphatic polyhydroxy compounds such as ethylene glycol and polyethylene glycol, and mixtures thereof. Furthermore, these epoxy resins are a mixture of a reactive diluent containing at least one epoxy group, such as butyl glycidyl ether. In addition, bromine-containing epoxy resins include bis(4-hydroxyphenyl) alkanes such as bisphenol A and bisphenol F, which are liquid at room temperature;
Bromine-substituted bis(4-
Epoxy resin obtained by reacting hydroxyphenyl) alkanes with epihalohydrin such as epibromhydrin or epichlorohydrin. Brominated bis(4-hydroxyphenyl) is solid at room temperature but dissolves in liquid epoxy resin. ) Diglycidyl ethers obtained by reacting alkanes with epihalohydrin, bis(4-
Diglycidyl ethers obtained by reacting diglycidyl ethers of hydroxyphenyl) alkanes with bromine-substituted bis(4-hydroxyphenyl)alkanes, and further bromine-containing ethers such as dibromucresyl glycidyl ether. Also included are reactive diluents and the like. Examples of compounds having at least two phenolic hydroxyl groups in the molecule include dihydric phenols such as catechol, resorcinol, bisphenol A, bisphenol F, and tetrabromobisphenol A, pyrogallol, phenol novolac resins,
It is a polyhydric phenol such as cresol novolac resin, polyparavinylphenol, bromine-substituted polyparavinylphenol, or a mixture thereof. The blending ratio of the mixture of the epoxy resin and the compound having a phenolic hydroxyl group is as follows:
It is preferable to mix compounds having phenolic hydroxyl groups in the range of 0.05 to 0.5.
If the number of phenolic hydroxyl groups is less than 0.05, the curing speed will be slow, and the performance of the cured product improved by adding the compound, especially the improvement effect on bending strength, water resistance, etc., will be negligible, and the phenolic If the number of hydroxyl groups exceeds 0.5, curing will proceed before the powdered dicyandiamide is completely dissolved.
Perhaps because dicyandiamide remains unreacted in the cured product, the properties of the cured product, especially chemical resistance and heat resistance, are poor, so the number of phenolic hydroxyl groups per epoxy group is in the range of 0.05 to 0.5. It is necessary to mix compounds having phenolic hydroxyl groups so that In addition, when determining the blending composition, in order to improve the dispersion stability of dicyandiamide, 25% of the mixture was
It is necessary to adjust the specific gravity in the range of 1.33 to 1.52 at °C. For this purpose, it is preferable to mix a bromine-containing epoxy resin or a bromine-containing compound having a phenolic hydroxyl group such that the bromine content is approximately 16 to 32% by weight based on the mixture. By adjusting the bromine content to 16 to 32% by weight, flame retardancy can be imparted to the composition at the same time. The dicyandiamide used in the present invention can be produced using, for example, a “jet pulverizer” (manufactured by Nippon Neumatic Co., Ltd.).
Average particle size obtained by finely pulverizing with etc.
The diameter is 50 μm or less. The reason why the average particle size is set to be 50 μm or less is because if the average particle size exceeds 50 μm, even if the specific gravity of the mixture is in the range of 1.33 to 1.52, when the viscosity of the mixture decreases due to heating etc., dicyandiamide will settle. This is because floating is observed, curing progresses unevenly, and various properties of the cured product are inferior. In addition, in order for powdered dicyandiamide to completely dissolve and react before curing is completed, it is more preferable for the particle size of dicyandiamide to be small, and from this point of view as well, the average particle size of dicyandiamide is preferably 50 μm or less. is important. The epoxy resin composition of the present invention is produced by mixing the above-mentioned epoxy resin that is liquid at room temperature and a compound having a phenolic hydroxyl group at room temperature or up to 200°C, and adding dicyandiamide finely ground to an average particle size of 50 μm or less. In addition, it is manufactured by uniformly kneading with three rolls or the like. Since the phenolic hydroxyl group slightly reacts with the epoxy group during production, it is preferable to mix at as low a temperature as possible. Further, if it is necessary to further increase the curing speed of the composition, a curing accelerator may be used in combination. As the curing accelerator, for example, aliphatic tertiary amines having an aromatic ring such as benzyldimethylamine, unsaturated ring tertiary amines such as pyridine, 3 (3
Urea compounds such as -chlorophenyl)-1,1-dimethylurea, boron trifluoride amine complexes, imidazoles, etc. can be used. The amount to be used must be determined with sufficient care since the pot life of the composition will be shortened, but it is usually used in an amount of 1 part by weight or less based on the epoxy resin. The epoxy resin composition of the present invention obtained in this way has good storage stability at low temperatures because it has dicyandiamide, which is a latent curing agent, dispersed in powder form, and also has phenolic hydroxyl groups. The curing reaction proceeds rapidly by heating to a temperature above ℃. In addition, by setting the average particle size of dicyandiamide to 50 μm or less and adjusting the specific gravity of the epoxy resin mixture at 25°C to a range of 1.33 to 1.52 to approximate the specific gravity of dicyandiamide, we have made it possible to maintain the temperature not only at room temperature but also at 40 to 80°C. Even if the viscosity of the composition is lowered by heating to a temperature higher than 100 nm, the dispersion stability is good. The epoxy resin composition of the present invention can be used for lamination, casting, impregnation, painting, etc. by adding various additives such as quartz powder, inorganic fillers such as mica, pigments, and dyes as necessary. Even in these applications, by using dicyandiamide with an average particle size of 50 μm or less, it can sufficiently penetrate into the minute parts of the base material and cure progresses uniformly, so the resulting cured product has excellent mechanical properties and electrical properties. Excellent physical properties, thermal properties, chemical resistance, etc. Example 1 84 g of bisphenol A, 109 g of tetrabromo bisphenol A, and 260 g of epichlorohydrin were mixed and dissolved in a separable flask, sodium hydroxide was added as a reaction catalyst, and the mixture was reacted at 80°C for about 4 hours, and excess epichlorohydrin was removed under vacuum. The resulting sodium chloride was washed with water to obtain an epoxy resin with a bromine content of 24% by weight and an epoxy equivalent of 248. Take 200 g of the obtained epoxy resin into another separable flask, add 45 g of bisphenol A, and stir and mix at 120°C for about 30 minutes.
A homogeneous mixture was obtained. The specific gravity of this mixture at 25°C was 1.38, the viscosity at 35°C was 400 poise, and the bromine content was 19.5% by weight. To the resulting mixture, add 8 g of dicyandiamide powder with an average particle size of 15 μm and 0.5 g of benzyldimethylamine.
In addition, the mixture was kneaded using three rolls to obtain an epoxy resin composition. The stroke cure of the resulting composition is 180℃
It took 250 seconds. The viscosity of the composition at 60° C. was 14 poise, and after being left at this temperature for 5 hours, the viscosity became 28 poise, but no precipitation of the dicyandiamide powder was observed. Example 2 AER331 (manufactured by Asahi Kasei Industries, Ltd., bisphenol A)
Diglycidyl ether, epoxy equivalent weight 190) 520
g, DER542 (manufactured by Dow Chemical, tetrabromo bisphenol A diglycidyl ether, epoxy equivalent 345, bromine content 48% by weight) 280 g, bisphenol A 120 g, phenol novolac resin (average molecular weight 350) 20 g and as a reactive diluent.
60 g of BROC (manufactured by Nippon Kayaku Co., Ltd., dibromucresyl glucidyl ether) was placed in a separable flask and stirred and mixed at 120° C. for about 30 minutes to obtain a homogeneous mixture. The specific gravity of this mixture at 25℃ is 1.33,
The viscosity at 35℃ is 160 poise and the bromine content is 16
It was in weight%. To the obtained mixture, 40 g of dicyandiamide powder with an average particle size of 15 μm and 3 (3-
5g of chlorphenyl-1,1-dimethylurea
In addition, the mixture was kneaded using three rolls to obtain an epoxy resin composition. The stroke cure of the resulting composition is 180℃
It took 160 seconds. Further, the viscosity of the composition at 60° C. was 8 poise, and the viscosity after standing at this temperature for 5 hours was 10 poise, with no sedimentation of the dicyandiamide powder observed. Example 3 AER331 (manufactured by Asahi Kasei Industries, Ltd., bisphenol A)
Diglycidyl ether, epoxy equivalent 190) 650g
and 350 g of tetrabromobisphenol A were placed in a separable flask and stirred and mixed at 120° C. for about 1 hour to obtain a homogeneous mixture. The specific gravity of this mixture at 25°C was 1.39, the viscosity at 35°C was 500 poise, and the bromine content was 20% by weight. To the resulting mixture, add 30 g of dicyandiamide powder with an average particle size of 15 μm and 2 g of benzyldimethylamine.
was added and kneaded using three rolls to obtain an epoxy resin composition. The stroke cure of the resulting composition is 180℃
It took 300 seconds. The viscosity of the composition at 60° C. was 18 poise, and the viscosity after standing at this temperature for 5 hours was 35 poise, with no precipitation of dicyandiamide powder observed at all. Example 4 The mixture obtained in Examples 1 and 2 and as a comparative example AER331 (manufactured by Asahi Kasei Corporation, bisphenol A diglycidyl ether, epoxy equivalent 190) 630
g, 250 g of DER542 (manufactured by Dow Chemical, tetrabromo bisphenol A diglycidyl ether, epoxy equivalent 345, bromine content 48% by weight) and 120 g of bisphenol A were mixed and dissolved to determine the bromine content.
A mixture of 12% by weight, specific gravity at 25°C of 1.28, and viscosity at 30°C of 150 poise was obtained. A composition obtained by adding 4 parts by weight of dicyandiamide powder with average particle diameters of 15 μm, 45 μm, and 75 μm to these mixtures was taken into a sedimentation tube and left at 80°C for 10 hours. Table 1 shows the amount of sedimentation of the dicyandiamide powder. . 【table】

Claims (1)

[Claims] 1 Epoxy resin (A) that is liquid at room temperature and a compound having at least two phenolic hydroxyl groups in the molecule
(B), which contains a bromine-containing compound in either or both of the epoxy resin (A) and the compound (B), and for each epoxy group of the epoxy resin (A), Phenolic hydroxyl group is 0.05-0.5
The compound (B) was mixed in a range of 25
A solvent-free epoxy resin composition characterized by containing 1 to 5 parts by weight of dicyandiamide powder with an average particle size of 50 μm or less per 100 parts by weight of a mixture that is liquid at room temperature and has a specific gravity in the range of 1.33 to 1.52 at °C. .