JPH05320482A - Flame-retarding epoxy resin composition - Google Patents

Abstract

PURPOSE:To obtain a resin composition which is lowly viscous and easily workable, excels in humidity resistance and flame retardancy and is reduced in the emission of smoke and noxious gases when heated or burnt without using any halogen-containing flame retardant. CONSTITUTION:This composition comprises an epoxy resin, an acid anhydride, a cure accelerator and a filler which comprises hydrated alumina having a conductivity of 30mus/cm or below, has a surface treated with a silane coupling agent, and is used in an amount of 250-450 pts.wt. per 100 pts.wt. epoxy resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flame-retardant epoxy resin composition, and more specifically, it has low smoke generation, little generation of harmful gases, and excellent flame resistance, flame retardancy and workability. It relates to an epoxy resin composition.

[0002]

2. Description of the Related Art Conventionally, epoxy resin has excellent electrical characteristics,
Since it has mechanical properties and crack resistance, and is excellent in adhesion to various materials, it is often used for electrical insulation, especially for casting, especially for insulation protection, high voltage characteristics (arc resistance, arc resistance,
Tracking resistance), crack resistance, and flame resistance are improved with flame-retardant epoxy resin insulation treatment of high-voltage parts,
That is, it is used for impregnation casting, and for example, a composition containing a large amount of a filler and a flame retardant in an acid anhydride-curable epoxy resin is used. Currently, a flame-retardant epoxy resin composition is generally added with a halogen-based flame retardant, a phosphorus-based flame retardant, an inorganic flame retardant, or the like to impart flame retardancy. As a combustion gas of this composition, harmful gases such as carbon monoxide, hydrogen cyanide, sulfurous acid gas, and hydrogen halide are generated. Especially when a halogen-based flame retardant is used,
A very harmful brominated benzodioxin and dibenzofuran may be produced, which is regarded as a problem. Also,
Moisture resistance and heat resistance are poor when phosphorus-based flame retardants are used,
When an inorganic flame retardant is used, sufficient flame retardancy cannot be obtained, and there is a problem that the viscosity is remarkably increased by increasing the amount and the workability is deteriorated.

[0003]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, does not use a halogen-based flame retardant, produces a small amount of smoke and a harmful gas during heating / combustion, and is resistant to moisture. And a flame-retardant epoxy resin composition having excellent flame retardancy, low viscosity, and excellent workability.

[0004]

Means for Solving the Problems The present inventors have found that by using a hydrated alumina having a small conductivity as a filler and a surface of the filler treated with a silane coupling agent in a specific blending amount, The present invention has been achieved by finding that the above problems can be solved.

The present invention provides a flame-retardant epoxy resin composition containing an epoxy resin, an acid anhydride, a curing accelerator and a filler, and the filler having an electric conductivity of 30 μS / cm.
The present invention also relates to a flame-retardant epoxy resin composition obtained by mixing 250 to 450 parts by weight of water surface alumina whose surface of a filler is treated with a silane coupling agent with 100 parts by weight of an epoxy resin.

The epoxy resin used in the present invention has at least one epoxy group in the molecule,
For example, a bisphenol A type epoxy resin obtained from bisphenol A and epichlorhydrin, a bisphenol F type epoxy resin obtained from bisphenol F and epichlorhydrin, phthalic acid, tetrahydrophthalic acid, hexahydroxyphthalic acid, sebacic acid, Glycidyl esters of polycarboxylic acids such as dodecanoic acid, 1,4
-Glycidyl ethers of polyhydric alcohols such as butanediol, 1,6-hexanediol, polyethylene glycol, polypropylene glycol, trimethylolpropane, 3,4-epoxycyclohexylmethyl (3,4
Examples include alicyclic epoxy resins such as epoxycyclohexane) carboxylate and epoxy compounds of liquid polyptadiene.

Examples of the acid anhydride used in the present invention include methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, phthalic anhydride, hexahydrophthalic anhydride, endomethylenetetrahydrophthalic anhydride, dodecenylsuccinic anhydride and octenyl. Examples thereof include succinic anhydride and polyazelaic acid polyanhydride. The amount of the acid anhydride used is preferably in the range of 0.6 to 1.3 equivalents per equivalent of the epoxy group contained in the epoxy resin.

As the curing accelerator used in the present invention,
Examples thereof include imidazoles such as 2-ethyl 4-methylimidazole, 1-cyanoethyl 4-methylimidazole, 1-benzyl 2-ethylimidazole and derivatives thereof, and tertiary amines such as trisdimethylaminomethylphenol. The amount of the curing accelerator used is not particularly limited, but is preferably in the range of 0.1 to 5.0 parts by weight per 100 parts by weight of acid anhydride.

The filler used in the present invention is a hydrated alumina which is effective in moisture resistance and flame retardancy, has an electric conductivity of 30 μS / cm or less, and has its surface treated with a silane coupling agent. The compounding amount thereof is in the range of 250 to 450 parts by weight with respect to 100 parts by weight of the epoxy resin. Even if silica, talc, calcium carbonate, clay or the like other than hydrated alumina is used as the filler, excellent moisture resistance and flame retardancy (UL94V-0) cannot be obtained. The treatment of the filler with the silane coupling agent is
The filler is dispersed in water or an organic solvent to form a slurry, the silane coupling agent is added while stirring the slurry, and the filler is dried. The filler may be stirred to spray an aqueous solution of the silane coupling agent and then dried. Alternatively, the high temperature filler immediately after being taken out of the furnace may be sprayed with the aqueous solution of the silane coupling agent.

Examples of the silane-based coupling agent used in the present invention include vinylsilane-based, acrylsilane-based, epoxysilane-based, and aminosilane-based coupling agents. For example, vinyltrichlorosilane, vinyltris (β-methoxyethoxy) silane, vinyltriethoxysilane, vinyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, β- (3,
4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ
-Glycidoxypropylmethyldiethoxysilane, N-
β (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β (aminoethyl) -γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, Examples include γ-mercaptopropyltrimethoxysilane and γ-chloropropyltrimethoxysilane. The hydrated alumina treated with the silane coupling agent may be further treated (double-coated) with fatty acid or stearic acid. The amount of the silane coupling agent to be treated as the filler is not particularly limited, but the filler 10
The range of 0.1 to 3.0 parts by weight per 0 parts by weight is preferable. If the blending amount of the hydrated alumina is less than 250 parts by weight, flame retardancy (UL94V-0) cannot be obtained, and if it exceeds 450 parts by weight, the viscosity remarkably increases and the workability deteriorates. Further, the one using hydrated alumina having a conductivity of more than 30 without surface treatment is inferior in workability and remarkably deteriorates in moisture resistance. As the filler, a specific amount of the above-mentioned hydrated alumina is used, but in addition to these, fillers such as silica, talc, calcium carbonate and clay can also be used together.

The flame-retardant epoxy resin composition of the present invention comprises
If necessary, coloring agents such as antimony trioxide, red iron oxide, ferric oxide, carbon, titanium white, silane-based or titanium-based coupling agents, silicone-based defoaming agents, epoxies such as monoglycidyl ether, diglycidyl ether, etc. A reactive diluent and the like can also be added.

[0012]

EXAMPLES The present invention will be described below with reference to examples. "Parts" in the following examples means parts by weight. The characteristics of the flame-retardant epoxy resin composition having the composition shown in Table 2 were measured. Flame retardant epoxy resin composition at 70 ° C for 2.5 hours, then 11
Cured at 0 ° C. for 2.5 hours. Moreover, each characteristic was measured by the method shown below. (1) Average particle diameter of filler: using Shimadzu Corporation's Sedigraph 500ET, sample concentration of about 8% by weight, starting particle diameter of 50 μm, dispersion of sodium hexametaphosphate 0.1% by weight and preliminary dispersion exceeding Sonic cleaning was carried out for 20 minutes to prepare a particle size distribution chart to determine the cumulative weight% of the particle size, and the average particle size showed a particle size (μm) with a cumulative weight (%) of 50%. (2) Viscosity: Measured at a measurement temperature of 25 ° C. using a B type rotational viscometer. (3) Flame retardancy: Test piece thickness 1.58 according to UL94
Evaluation was made with a sample of mm. (4) Conductivity: 30 g of the sample was suspended in 100 ml of water at 85 ° C., and after cooling, the conductivity (μS / cm) of the suspension was measured with a conductivity meter. (5) Moisture resistance: The epoxy resin composition is stirred under predetermined conditions.
After mixing, a hardened plate (1.6 mm thickness) is created under predetermined conditions, and then the hardened plate cut out into 10 cm × 10 cm is put in a high pressure steam sterilizer manufactured by Yamatra Botech Co., Ltd. (2.1 at).
m, 120 ° C.) for 50 hours, and evaluated by the dielectric breakdown strength (kV / mm) in terms of 1 mm. Moisture resistance: evaluated according to the following criteria. ◯: Dielectric breakdown strength after 50 hours is 15 kV / mm or more ×: Dielectric breakdown strength after 50 hours is less than 15 kV / mm Note that the types, manufacturers and characteristics of the fillers used in Examples and Comparative Examples are shown below. The composition (unit is parts by weight) of the resin composition shown in FIG.

[0013]

[Table 1]

[0014]

[Table 2]

Examples 1 to 4 Among the fillers in Table 1, hydrated alumina whose conductivity is 30 μS / cm or less and whose surface is treated with a composite system of an acrylic silane coupling agent and stearic acid. All of the epoxy resin compositions containing 250 to 500 parts by weight of 100 parts by weight of the epoxy resin have excellent moisture resistance, and flame retardancy shows a high level of 94 V-0 according to UL standard. . Comparative Example 1 Among the fillers shown in Table 1, hydrated alumina whose conductivity is 30 μS / cm or less and whose filler surface is not treated with a silane coupling agent is 300 parts by weight with respect to 100 parts by weight of an epoxy resin.
The epoxy resin composition blended in parts by weight has excellent moisture resistance and flame retardancy, but has a higher viscosity and poorer workability than an epoxy composition using hydrated alumina whose surface of the filler has been treated and modified. Comparative Example 2 Among the fillers in Table 1, hydrated alumina whose conductivity is 30 μS / cm or less and whose filler surface is treated with an acrylic silane coupling agent is 230 parts by weight with respect to 100 parts by weight of the epoxy resin. The epoxy resin composition obtained by blending less than the above parts has excellent moisture resistance, low viscosity and excellent workability, but flame retardancy (UL94V-0) cannot be obtained. Comparative Example 3 Among the fillers in Table 1, the conductivity was 30 μS / cm or less, and 480 parts by weight of hydrated alumina obtained by treating the surface of the filler with an acrylic silane coupling agent was used with respect to 100 parts by weight of the epoxy resin. The epoxy resin composition obtained by blending more than 100 parts has excellent moisture resistance and flame retardancy (UL94V-
It is also excellent in 0), but the viscosity is remarkably increased and the workability is poor. Comparative Example 4 Among the fillers in Table 1, 300 parts by weight of hydrated alumina whose conductivity is 30 μS / cm or more and whose filler surface is not treated with a silane coupling agent is used per 100 parts by weight of the epoxy resin. The epoxy resin composition obtained by blending is excellent in flame retardancy, but inferior in workability and moisture resistance.

[0016]

The flame-retardant epoxy resin composition of the present invention is
Without using a halogen-based flame retardant, the amount of smoke and the amount of harmful gas generated at the time of heating / combustion are small, the humidity resistance and flame retardancy are excellent, and the viscosity is low and the workability is excellent. The flame-retardant epoxy resin composition of the present invention can be widely used for impregnation and casting of flyback transformers, high-voltage transformers, power transformers, switching transformers, solenoid coils and the like.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masahiro Suzuki Masahiro Suzuki 13-13-1, Higashimachi, Hitachi City, Ibaraki Hitachi Chemical Co., Ltd. Yamazaki Factory (72) Inventor Mitsuo Ohara 4-13, Higashimachi, Hitachi City, Ibaraki Prefecture No. 1 Hitachi Chemical Co., Ltd. Yamazaki Factory

Claims (1)

[Claims] 1. A flame-retardant epoxy resin composition containing an epoxy resin, an acid anhydride, a curing accelerator and a filler, wherein the filler has an electric conductivity of 30 μS / cm or less, and the surface of the filler is silane. Hydrated alumina treated with a coupling agent was added to 100 parts by weight of the epoxy resin.
A flame-retardant epoxy resin composition containing 250 to 450 parts by weight.