JP2001172555A - Flame-retardant epoxy resin powder coating material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide flame-retardant epoxy resin powder coating materials having excellent flame retardance without using a halogen based flame-retardant, and excellent curability and moisture resistance which are important as insulating coating materials. SOLUTION: Into the epoxy resin compositions comprising an epoxy resin, a curing agent, a filler, and a flame-retardant as the essential components, a phosphorus-containing compound of the formula, wherein n is 1-3; and R is -CH3, -CH2NH3 or -CH2 NHCH3 is incorporated as the flame-retardant component. It is preferred to incorporate this phosphorus compound at a phosphorus content of 1.5-3.5 wt.% based on the sum of the epoxy resin and the curing agent.

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 powder coating having excellent flame retardancy without using a halogen-based flame retardant.

[0002]

2. Description of the Related Art Epoxy resin powder coatings used for insulating electrical and electronic parts are required to have high flame retardancy in order to ensure the safety of parts against fire. . For this reason, various compounds imparting flame retardancy are blended in the components of the powder coating. Non-flammable inorganic fillers that reduce the amount of flammable resin components, especially inorganic fillers such as aluminum hydroxide and magnesium hydroxide that contain water of crystallization and emit fire during combustion to exhibit a flame-retardant effect A variety of methods have been proposed and implemented, such as a method of compounding a large amount of methacrylate, a method of modifying with a low flammable silicone resin or a resin containing a cyanurate ring, but the most widely practiced is the use of various halogen-based flame retardants. It is a method of blending.

Among these halogen compounds, aromatic bromine compounds exhibit a remarkable fire-extinguishing effect by diluting the combustible gas with hydrogen bromide generated during combustion, which is a non-flammable heavy gas that shields the periphery of combustibles from oxygen. However, it has been pointed out that this hydrogen bromide is corrosive, and that when thermally decomposed in the presence of oxygen, it forms highly toxic polybromodibenzofuran and polydibromodibenzooxin similar to the highly toxic dioxin structure. Under such circumstances, a flame-retardant system containing no halogen is desired.

For this reason, in recent years, as a flame retardant replacing bromine compounds, phosphorus compounds which form a char by dehydration during combustion and exhibit a heat shielding effect have been widely studied, and inorganic red phosphorus and various organic phosphorus compounds have been studied. Acid esters have been used. However, since the red phosphorus compound has a dark reddish brown color, it is unsuitable for light-colored products such as blue, yellow, and green, which is one of the characteristics of epoxy resin powder coatings, when used in epoxy powder coatings. There is an inconvenience limited to dark colors. In the case of any combination of various phosphoric acid esters, the curability is lowered, and the phosphoric acid ester compound is easily decomposed under the moisture absorption treatment, so that the moisture resistance of the coating film is lowered and is not suitable for practical use.

[0005] As phosphorus compounds imparting flame retardancy, various compounds have been proposed in addition to red phosphorus and phosphate esters. For example, as inorganic compounds, phosphates such as ammonium phosphate are said to have a flame-retardant effect in some applications, but effective results can be obtained with powder coatings that require a high degree of flame retardancy. It is not possible. On the other hand, it has been proposed to synthesize various novel epoxy resins containing phosphorus in the structure and to apply this resin. However, these resins usually have low phosphorus content of 3% or less, and thus have low flame retardancy. It is enough.

[0006] In order to solve the above-mentioned problems, the present inventors have conducted intensive studies on other phosphorus-containing compounds. As a result, among the phosphorus compounds used as a coloring inhibitor for plastics, 9,10-dihydro-9- Oxa-10-phosphaphenanthrene-10-oxide was found to be highly effective in imparting flame retardancy.

Embedded image

However, since this compound has a highly reactive P—H bond in the molecule, it reacts with the epoxy resin and inhibits the curing reaction between the epoxy resin and the curing agent component, thereby improving the curability of the epoxy powder coating. Significantly lowers. In addition, when the coating film of the epoxy resin powder coating is heated and cured, there is also a problem that the compound of the formula (2) and the epoxy resin are mixed and the appearance of the coating film is impaired. Attempts have been made to blend as a flame retardant a compound that has been previously subjected to an addition reaction with an epoxy resin in order to remove the reaction activity of the PH bond. However, the addition reaction increases the molecular weight and increases the phosphorus content. descend. Therefore, in order to impart sufficient flame retardancy, it is necessary to add a large amount of this flame retardant, which causes deterioration of various properties of the powder coating product.

[0008]

SUMMARY OF THE INVENTION The present invention provides an epoxy resin powder coating which has high flame retardancy without blending a halogen-containing compound and which does not impair properties such as curability and moisture resistance. To provide.

[0009]

The present invention relates to an epoxy resin composition containing an epoxy resin, a curing agent, a filler and a flame retardant as essential components.
A flame-retardant epoxy resin powder coating characterized by incorporating a phosphorus-containing compound represented by the formula:

Embedded image That is, as a result of the inventor's intense study, the use of the compound represented by the general formula 1 obtained by the addition reaction of the compound of the formula 2 with an amine allows the addition of a small amount of the compound while imparting high flame retardancy. The inventors have found that the curability and the properties of the cured product are not inferior to those of conventional products, and have completed the present invention. Since this compound has a high phosphorus content and a nitrogen atom which enhances the flame-retarding effect in the molecule, a high degree of flame retardancy can be imparted with a relatively small amount of addition.

The compound represented by the general formula 1 can be easily obtained by carrying out an addition reaction of the compound of the formula 2 with a tertiary amine. This compound has a high phosphorus content and has a nitrogen atom that enhances the flame-retardant effect in the molecule, so it is possible to impart a high level of flame retardancy with a small amount of compounding, but the effect on powder coating properties In order to reduce the viscosity and impart sufficient flame retardancy, it is desirable to mix the epoxy resin and the curing agent in a phosphorus content of 1.5 to 3.5% based on the total amount (weight ratio). If the phosphorus content is less than 1.5%, sufficient flame retardancy cannot be obtained, and if it exceeds 3.5%, no further improvement in the effect of imparting flame retardancy is observed.

[0011] The epoxy resin in the present invention includes 1
It may be a non-halogen epoxy resin having at least two epoxy groups in the molecule and a solid at room temperature applicable to general epoxy powder coatings, such as bisphenol A type and bisphenol F type. , Bisphenol S type, phenol novolak type, cresol novolak type, biphenyl type, naphthalene type, aromatic amine type and the like, but are not particularly limited thereto. These can be used alone or in combination of two or more.

[0012] The curing agent in the present invention is not particularly limited either, and various curing agents may be used alone or in combination depending on the purpose to which the epoxy resin powder coating is applied. The use of a curing agent is most desirable in terms of curing properties. Examples include aromatic amines such as diaminodiphenylmethane and aniline resin, condensates of aliphatic amines with aliphatic dicarboxylic acids, dicyandiamide and its derivatives, various imidazoles and imidazoline compounds, adipic acid, sebacic acid, phthalic acid, and maleic acid. Polydicarboxylic acids such as acids, trimellitic acid, benzophenone dicarboxylic acid and pyromellitic acid or their anhydrides, dihydrazides such as adipic acid and phthalic acid, phenol, cresol, xylenol, bisphenol A, etc. and condensates with aldehydes. Novolaks, carboxamides, methylolated melamines,
And block-type isocyanurates.

The ratio of the curing agent to the epoxy resin is determined as appropriate depending on the type of the epoxy resin and the curing agent used. It is suitable to use in the range of .2 equivalents. If necessary, a curing accelerator such as a tertiary amine or an imidazole may be used for these curing agents. Among them, the use of an organic phosphorus compound is desirable for enhancing the flame retardancy.

Further, as a filler, calcium carbonate, calcium sulfate, barium sulfate, aluminum hydroxide, magnesium hydroxide, aluminum oxide, crystal or fused silica, talc, kaolin, clay, mica, dolomite,
Wollastonite, glass fiber or glass beads, zircon, titanium compounds, molybdenum compounds, etc. are used alone or in combination. In addition, additives such as various pigments, leveling agents, coupling agents and defoamers are appropriately compounded. In addition, silicone resin is used to enhance flame retardancy.
Resins having a cyanurate ring skeleton, such as melamine resins,
Alternatively, non-halogen flame-retardant auxiliaries such as zinc borate and expandable graphite can be used as appropriate.

In the present invention, the method for producing the powder coating is not particularly limited, and may be a general method.
As an example, the raw material components mixed in a predetermined composition ratio are sufficiently uniformly mixed by a mixer, melt-mixed by an extruder or a twin-screw kneader, and then pulverized to an appropriate particle size by a pulverizer and classified. can get.

[0016]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples. The raw material components were mixed by a mixer at the composition ratio (parts by weight) shown in Table 1, melt-kneaded, and then pulverized by a pulverizer to obtain an epoxy resin powder coating having an average particle size of 40 to 60 µm.

[0017]

[Table 1]

(Materials Used) Epoxy resin ・ EP-1003: Bisphenol A type, made of oily shell epoxy 2. 2. Curing agent BTDA: benzophenone tetracarboxylic anhydride 3. Hardening accelerator ・ TPP: triphenylphosphine Filler ・ Fused silica: RD-8, manufactured by Tatsumori ・ Aluminum hydroxide: CL-310, manufactured by Sumitomo Chemical Pigment-White pigment (titanium oxide): TTO-55, manufactured by Ishihara Sangyo-Blue pigment (cyanine blue): Cyanine blue GH, manufactured by Sumitomo Chemical Co., Ltd. Additives-Silane coupling agent: A-187, manufactured by Nippon Unicar Flame retardant • Phosphate ester: PX-200 manufactured by Daihachi Chemical Co., Ltd. • 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (compound of formula 2) • Compound of formula 1 (in formula 1 n = 2 and R = -CH ₂
NH ₂ )

(Test Method) Gel time: hot plate method at 165 ° C (JIS C 21
61) 2. 2. Flame retardancy: UL94 method (test plate thickness: 1 mm) Moisture resistance: A 0.6 mm thick powder-coated ceramic capacitor was treated at 121 ° C. for 2 hours, and then judged by insulation resistance. ：: over 10 ¹² Ω, △: 10 ¹² to 10 ¹¹ Ω, ×: 10
Less than ¹¹ Ω

In Example 1, 1.0 equivalent of an aromatic acid anhydride was blended with respect to 1.0 equivalent of an epoxy resin, and the compound of the formula 1 was further added with a phosphorus content relative to the total amount of the epoxy resin and the curing agent. In Example 2, aluminum hydroxide was used as the filler in the formulation of Example 1, and all of them had high flame retardancy and were hardened. It excels in various properties required for powder coatings, such as properties and moisture resistance of cured products.

On the other hand, each of the comparative examples has a problem with some characteristics, and it is difficult to apply the present invention to a powder coating. In Comparative Example 1, a phosphate ester having a high effect of imparting flame retardancy was blended, but the moisture resistance was greatly reduced. Comparative Example 2 contains the compound of Formula 2 as a flame retardant and has high flame retardancy, but cures slowly. In Comparative Example 3, only aluminum hydroxide was used as the flame retardant, and sufficient flame retardancy was not obtained, and the moisture resistance was also reduced.

[0022]

According to the present invention, there is provided a conventional epoxy powder coating for electrical insulation which does not use a halogen-containing compound such as bromine or an antimony-based flame retardant, which has been pointed out to be environmentally harmful for imparting flame retardancy. While providing excellent flame retardancy,
An object of the present invention is to provide a flame-retardant epoxy resin powder coating excellent in properties such as curability, moisture resistance, and heat discoloration resistance.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) C08K 5/49 C08K 5/49 C08L 63/00 C08L 63/00 CF term (reference) 4J002 CC042 CC052 CC062 CC182 CD041 CD051 CD061 CD111 CD131 CM012 DE077 DE097 DE147 DE237 DG047 DG057 DJ007 DJ017 DJ037 DJ047 DJ057 DL007 EF066 EF076 EF116 EF126 EL136 EL146 EN076 EP006 EQ026 ER026 EU116 EU196 EW009 EW138 FA047 FA087 FD017 FD130 AF01 AD14 AF01 AD14 AF01 FD138 FD142 AF01 DC21 DC31 DC35 DC41 DC45 DD07 FA03 FA04 FA05 FA06 FB07 JA03 4J038 DA042 DA162 DB061 DB071 DB081 DB151 GA14 HA166 HA286 HA366 HA446 HA486 HA526 HA536 HA546 JA39 JA41 JA75 JB07 JB12 JB17 JB18 JB32 JC20 KA03 PC04 PC02

Claims (4)

[Claims] 1. An epoxy resin composition comprising an epoxy resin, a curing agent, a filler and a flame retardant as essential components, wherein a phosphorus-containing compound represented by the general formula 1 is blended as a flame retardant. Epoxy resin powder coating. Embedded image 2. The flame-retardant epoxy resin according to claim 1, wherein the phosphorus-containing compound is compounded in a phosphorus content of 1.5 to 3.5% by weight based on the total amount of the epoxy resin and the curing agent. Powder paint. 3. The flame-retardant epoxy resin powder coating according to claim 1, wherein the curing agent is an acid anhydride-based curing agent. 4. The flame-retardant epoxy resin powder coating according to claim 1, wherein an organic phosphorus compound is used as a curing accelerator.