JPH0372652B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an epoxy resin varnish suitable for lamination, painting, etc. used in the electrical and electronic industry fields. This invention relates to a high-solid flame-retardant epoxy resin varnish that has good properties and gives a uniformly 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. Increasing power consumption and high solidity are becoming major issues. The present invention solves the above problems and provides a high solids flame retardant epoxy resin varnish. That is, the present invention provides a mixed solution in which an epoxy resin (A) and a compound (B) having at least two phenolic hydroxyl groups in the molecule are dissolved in a common solvent (C) for both, Either or both of the resin (A) and the compound (B) having a phenolic hydroxyl group contains a bromine-containing compound, and the phenolic hydroxyl group is 0.05 to 1 per epoxy group of the epoxy resin (A). The compound (B) was blended so that the number was within the range of 0.5, and the common solvent (C) was further added.
This is a flame-retardant epoxy resin varnish characterized by mixing dicyandiamide powder with an average particle size of 50 μm or less in a dispersed state into a mixed solution having a specific gravity in the range of 1.33 to 1.52 at °C. The epoxy resin used in the present invention is 2,2-
Diglycidyl of bis(4-hydroxyphenyl)alkanes such as bis(4-hydroxyphenyl)propane (hereinafter referred to as bisphenol A) and bis(4-hydroxyphenyl)methane (hereinafter referred to as bisphenol F) These include ethers, polyglycidyl ethers of polyhydric phenols such as phenol novolak and cresol novolak, polyglycidyl ethers of aliphatic polyhydroxy compounds such as ethylene glycol and polyethylene glycol, and mixtures thereof. 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 resins obtained by reacting hydroxyphenyl) alkanes with epihalohydrins such as epibromhydrin and epichlorohydrin, and epoxy resins obtained by reacting bromine-substituted bis(4-hydroxyphenyl)alkanes with epihalohydrin. Diglycidyl ethers, bis(4
These include diglycidyl ethers obtained by reacting diglycidyl ethers of -hydroxyphenyl)alkanes with bromine-substituted bis(4-hydroxyphenyl)alkanes. It is also possible to use reactive diluents containing at least one epoxy group, such as butyl glycidyl ether, dibromucresyl glycidyl ether, 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 is slow, and the performance of the cured product that is improved by adding the compound, especially flexural strength, water resistance, etc., is hardly improved, and if the number of phenolic hydroxyl groups exceeds 0.5, the powder-like Curing progresses before the dicyandiamide is completely dissolved, and dicyandiamide remains unreacted in the cured product, resulting in poor properties of the cured product, especially chemical resistance and heat resistance. On the other hand, it is necessary to blend so that the number of phenolic hydroxyl groups is in the range of 0.05 to 0.5. Common solvents for both include acetone, methyl ethyl ketone, toluene, xylene, and the like. In addition, when determining the blending composition, in order to improve the dispersion stability of dicyandiamide, 25% of the mixed solution was
It is necessary to adjust the specific gravity to a range of 1.33 to 1.52 at °C, and for this purpose, add a bromine-containing epoxy resin or a bromine-containing compound having a phenolic hydroxyl group to a mixture of the two. It is preferable that the amount of the solvent be about 16 to 32% by weight, and furthermore, the amount of the common solvent for both should be 20 parts by weight or less based on 100 parts by weight of the mixture. By adjusting the bromine content to 16-32% by weight of the mixture, flame retardancy can be imparted to the composition at the same time. The dicyandiamide used in the present invention has an average particle size of 50 μm obtained by finely pulverizing it with, for example, a jet pulverizer (manufactured by Nippon Neumatic Co., Ltd.).
These are as follows. 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 varnish of the present invention is produced by mixing and dissolving a mixture of an epoxy resin, a compound having a phenolic hydroxyl group, and a common solvent for both at a temperature between room temperature and 200°C to obtain a mixed solution.
Add dicyandiamide finely ground to 50μm or less,
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, the amount of dicyandiamide used is preferably 1 to 5 parts by weight per 100 parts by weight of the epoxy resin and the compound having a phenolic hydroxyl group. Furthermore, if it is necessary to increase the curing speed of the varnish, a curing accelerator may be used in combination. Examples of curing accelerators include aliphatic tertiary amines with an aromatic ring such as benzyldimethylamine, unsaturated ring tertiary amines such as pyridine, 3(3-chlorophenyl)-1,1-dimethylurea, etc. urea compounds,
Boron trifluoride amine complexes, imidazoles, etc. can be used. Further, 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 varnish of the present invention obtained in this way has good storage stability at low temperatures because it has dicyandiamide, which is a latent hardening agent, dispersed in powder form, and has a 100% The curing reaction proceeds rapidly by heating to a temperature above ℃. In addition, by adjusting 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, it is possible to ℃
Even if the viscosity of the varnish is lowered by heating at a temperature of 100° C., the dispersion stability is good. The epoxy resin varnish of the present invention can be used for lamination, painting, etc. by adding various additives such as inorganic fillers such as talc and quartz, pigments, and dyes, if 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 200g of the obtained epoxy resin into another separable flask, add 45g of bisphenol A and 15g of methyl ethyl ketone,
The mixture was stirred and mixed at 100°C for about 30 minutes to obtain a uniform mixed solution. The specific gravity of this mixed solution at 25℃ is 1.33, 35
The viscosity at °C was 15 poise, and the bromine content was 19.5% by weight based on solid content. For the obtained mixed solution, for the obtained mixed solution, the average particle size
8 g of 15 μm dicyandiamide powder and 0.5 g of benzyldimethylamine were added and kneaded using three rolls to obtain an epoxy resin varnish. The resulting varnish stroke cure is 180℃
It took 250 seconds. Further, the viscosity of the varnish at 60° C. was 1.2 poise, and after being left at this temperature for 5 hours, the viscosity became 1.6 poise, but no sedimentation of the dicyandiamide powder was observed. Example 2 AER331 (manufactured by Asahi Kasei Industries, Ltd., bisphenol A)
Diglycidyl ether, epoxy equivalent weight 190) 480
g, DER542 (manufactured by Dow Chemical, tetrabromo bisphenol A diglycidyl ether, epoxy equivalent 345, bromine content 48% by weight) 320 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 glycidyl ether) and 25 g of acetone were placed in a separable flask and stirred and mixed at 60° C. for about 30 minutes to obtain a uniform mixed solution. The specific gravity of this mixed solution at 25°C was 1.33, the viscosity at 35°C was 7 poise, and the bromine content was 18% by weight based on the solid content. To the obtained mixed solution, 40 g of dicyandiamide powder with an average particle size of 15 μm and 5 g of 3(3-chlorophenyl)-1,1-dimethylurea were added.
The mixture was kneaded using this roll to obtain an epoxy resin varnish. The resulting varnish stroke cure is 180℃
It took 160 seconds. Further, the viscosity of the varnish at 45° C. was 3 poise, and the viscosity did not change even after being left at this temperature for 5 hours, and no sedimentation of the dicyandiamide powder was observed. Example 3 AER331 (manufactured by Asahi Kasei Industries, Ltd., bisphenol A)
Diglycidyl ether, epoxy equivalent 190) 650g
Then, 350 g of tetrabromobisphenol A and 50 g of methyl ethyl ketone were placed in a separable flask and mixed with stirring at 100° C. for about 30 minutes to obtain a uniform mixed solution. The specific gravity of this mixed solution at 25℃ is
The viscosity at 1.35°C and 35°C was 20 poise, and the bromine content was 20% by weight based on the solid content. To the obtained mixed solution, 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 varnish. The resulting varnish stroke cure is 180℃
It took 300 seconds. Further, the viscosity of the varnish at 60°C was 1.5 poise, and the viscosity after standing at this temperature for 5 hours was 2.5 poise, with no sedimentation of the dicyandiamide powder being observed. Example 4 70 g of methyl ethyl ketone was further added to the mixed solution obtained in Examples 1 and 3 and the mixed solution obtained in Example 3 as a comparative example to obtain a specific gravity of 1.28 at 25°C. To these mixed solutions, 4 parts by weight of dicyandiamide powder with average particle diameters of 15 μm, 45 μm, and 75 μm were added to the varnish, which was taken into a sedimentation tube and left at 60°C for 10 hours. The amount of sedimentation of the dicyandiamide powder is shown in Table 1. Shown below. 【table】

Claims (1)

[Claims] 1. 20 parts by weight of a common solvent (C) for 100 parts by weight of a mixture of an epoxy resin (A) and a compound (B) having at least two phenolic hydroxyl groups in the molecule. The following is a mixed solution of dissolved epoxy resin.
Either or both of (A) and the compound (B) having a phenolic hydroxyl group contain a bromine-containing compound, and the phenolic hydroxyl group is 0.05 to 0.5 per epoxy group of the epoxy resin (A). The compound (B) is blended so that the specific gravity at 25°C is 1.33 to
For mixed solutions in the range of 1.52, the average particle size
A high solids type flame retardant epoxy resin varnish characterized by mixing dicyandiamide powder of 50 μm or less in a dispersed state. 2. The high solids according to claim 1, characterized in that 1 to 5 parts by weight of dicyandiamide powder is blended with 100 parts by weight of the mixture of the epoxy resin (A) and the compound having a phenolic hydroxyl group (B). Mold flame retardant epoxy resin varnish.