JPH04142360A - Flame-retardant resin composition - Google Patents

Abstract

PURPOSE:To prepare the title compsn. which is excellent in flame retardance and heat resistance and generates no toxic gas during burning by compounding an epoxy resin with magnesium hydroxide comprising particles of a hexagonal plate shape. CONSTITUTION:The title compsn. is prepd. by compounding 100 pts.wt. epoxy resin (e.g. a bisphenol A epoxy resin) with 5-300 pts.wt. magnesium hydroxide comprising particles of a hexagonal plate shape with a mean particle size of 0.6-1mum. A commercially available magnesium hydroxide, such as KX-80, 200-06 (a product of Asahi Glass Co., Ltd.), or PT-25 (a product of Shin Nihon Chemical Industry Co., Ltd.), can be used as it is. The compsn. may further be compounded with a filler, a rubber component, a diluent, a colorant, etc., and is suitably used in areas of sealing and impregnating an electric part.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a flame-retardant resin composition, and in particular a flame-retardant resin composition with excellent heat resistance suitable for sealing and impregnating electrical parts. It is about things.

<Prior Art> Epoxy resin compositions have been widely used for the purpose of moisture proofing and insulating electrical and electronic components such as resistors, capacitors, transformers, motors, and diodes. on the other hand,
As shown by the tightening of UL standards in the United States, the demand for flame retardant properties for these electrical parts is becoming stronger, and it is well known that epoxy resin sealants and impregnants are being made flame retardant. That's right.

Conventionally, commonly used methods for making epoxy resin compositions flame retardant include adding and mixing phosphorus or phosphate esters, using phosphorus and inorganic hydroxides such as aluminum hydroxide together, and using halogen-containing hydroxides. Additive flame retardants such as perchloropentacyclodecane, hexabromobenzene, decabromo biphenyl, decabromodiphenyl oxide, tetrabromo bisphenol A1 chlorinated paraffin, etc., with antimony trioxide added as a flame retardant aid, are used as epoxy How to add and mix with resin,
Alternatively, a method is used in which halogen is introduced into the molecular structure to make the resin itself flame retardant, as in the case of epoxy resins in which both ends of a copolymer of tetrabromobisphenol A and bisphenol A are converted into glycidyl ethers.

However, in flame retardant methods using phosphorus as the main ingredient, the hygroscopicity of phosphoric acid produced during kneading of phosphorus and resin components may cause a decrease in the properties as an electrical insulating material. In fact, phosphorus-based flame retardant resins generally have lower insulation resistance than halogen-containing flame retardant additives.

On the other hand, a combination of a halogen-containing flame retardant and antimony trioxide has good properties as a sealant for electrical parts, such as flame retardancy and insulation resistance, but antimony trioxide has toxicity and supply issues. Stability has recently been pointed out. Additionally, halogen-containing additive flame retardants and antimony trioxide are generally expensive. Moreover, although conventional flame retardants containing halogen elements have a high flame retardant effect, they have problems such as smoke generation and generation of toxic gases during combustion.
An epoxy resin composition has been proposed in which at least one metal compound selected from oxides, hydroxides, basic carbonates, organic acid metal salts, and complex compounds of Co, Ni, and Pt is used as a flame retardant. (Special Publication No. 62-42927)
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<Problem to be solved by the invention> However, in the conventional method, especially when magnesium hydroxide is used as a flame retardant, sufficient mixing is not achieved, resulting in a cured product becoming crumbly and not a normal cured product. There was a problem with not being able to get it.

<Means for Solving the Problems> The present inventors have conducted extensive studies with the aim of providing a composition that allows a normal cured product to be obtained even when magnesium hydroxide is used as a flame retardant, and as a result, the present invention has been developed. Reached.

That is, the present invention is a flame-retardant resin composition comprising 100 parts by weight of an epoxy resin and 5 to 300 parts by weight of hexagonal plate-shaped magnesium hydroxide with an average particle size of 0.6 to 1.0 μm.

The present invention will be explained in detail below.

The epoxy resin used in the present invention has two
There is no particular restriction as long as it has at least two epoxy groups, such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, 3,3'-diallyl bisphenol A diglycidyl ether, phenol novolak type epoxy resin, cresol novolac type epoxy resin. Epoxy resin, phloroglucinol triglycidyl ether, resorcin diglycidyl ether, tetraglycidyldiaminodiphenylmethane, triglycidylmethaminophenol, 1.5-naphthalenediol diglycidyl ether, 1゜6-naphthalenediol diglycidyl ether, 3.3' , 5,5'-tetramethyl-4,4
' -Biphenol diglycidyl ether, 4.4'
-Biphenol diglycidyl ether, neopentyl glycol diglycidyl ether, adipic acid diglycidyl ester, 0-phthalic acid diglycidyl ester, tris(4-hydroxyphenyl)methane triglycidyl ether, 1,3-bis[3-(o- Hydroxyphenyl)propyl] 1,1.3.3-tetramethyldisiloxane diglycidyl ether, 1,3-bis(3-hydroxypropyl) 1,1.3.3-tetramethyldisiloxane diglycidyl ether, linear aliphatic epoxy resin,
Examples include alicyclic epoxy resins and heterocyclic epoxy resins. Among these, those preferably used are epoxy resins that are liquid at room temperature or have a softening point of 100° C. or less.

Most preferably, the formula: where n is the average degree of polymerization, is 0 or at most 15
A bisphenol A type epoxy resin is used, which represents a positive integer up to a degree.

The curing agent used in the present invention is not particularly limited as long as it is a curing agent for ordinary epoxy resins, and examples include bisphenol A1 bisphenol F144'-dihydroxybiphenyl, 3,3'-diallylbisphenol A1 hydroquinone, phloroglucinol, Phenolic compounds such as 1,2,4-) hydroxybenzene, salicylic acid, phenol novolak resin, cresol novolac resin: 4,4'-diaminodiphenylsulfone, 4,4'-'methylenebis(2-ethylani IJ):
/), aromatic polyamines such as 4.4'-diaminodiphenylmethane, aliphatic polyamines such as diaminomaleonitrile and their derivatives, polyamide resins, amine compounds such as amine imide compounds: phthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydro anhydride Acid anhydrides such as phthalic acid, trimellitic anhydride, pyromellitic anhydride, adipic dihydrazide, isophthalic acid dihydrazide, eicosanniic acid dihydrazide, 7,11-octadecadiene-1,18-dicarbohydrazide, 1.
Examples include hydrazide compounds such as 3-bis(hydrazinocarboethyl)-5-isopropylhydantoin; addition reaction products of dicyandiamide, epoxy and imidazole, Lewis acid complex compounds such as boron trifluoride complex compounds, and metal chelate compounds. .

Furthermore, in the present invention, among conventionally known curing accelerators, those having an action as a curing agent can also be used. Specific examples thereof include, for example, 2-methylimidazole,
2-ethyl-4methylimidazole, 2-phenyl-4
-Methylimidazole, 2-phenyl-4-methyl-5
- imidazole compounds such as hydroxymethylimidazole or acid addition salts thereof such as hydroxybenzoic acid, N,N'-dimethylpiperazine, 2,4,6-)lis(dimethylaminomethyl)phenol, 1,8-diazabicyclo(5 , 4°0) amine compounds such as undecene-7,4-dimethylaminopyridine, or acid addition salts thereof such as hydroxybenzoic acid or dihydroxybenzoic acid.

The amount of curing agent added to the composition of the invention is usually 0.1 to 200 parts by weight per 100 parts by weight of epoxy resin.

Other commonly used known curing accelerators may be added to the composition of the present invention, if necessary.

Examples of curing accelerators include, in addition to the compounds that can be included as curing agents mentioned above, triphenylphosphine, tricyclohexylphosphine, bis(diphenylphosphino)methane, tris(2,6-cymethoxyphenyl) ) Phosphine compounds such as phosphine; metal acetylacetonates such as aluminum acetylacetonate and cobalt acetylacetonate.

When adding the above-mentioned curing accelerator to the composition of the present invention,
Usually 0.1 to 20 parts by weight per 100 parts by weight of epoxy resin
0 parts by weight is added.

In the present invention, as a flame retardant, an average particle size of 0.6 to 1
．． It is important to use magnesium hydroxide in the form of a 0 μm hexagonal plate.

As the magnesium hydroxide used in the present invention, those commercially available under the trade names rKX-80J r200-06H,J (Asahi Glass ■) or rPT-25J (Shin Nihon Kagaku Kogyo ■) can be used as they are.

Magnesium hydroxide is blended in an amount of 5 to 300 parts by weight, preferably 10 to 150 parts by weight, per 100 parts by weight of the epoxy resin. If the amount is less than 5 parts by weight, sufficient flame retardancy will not be obtained, and if it exceeds 300 parts by weight, the mechanical properties of the epoxy resin will deteriorate. Magnesium hydroxide may be used untreated, but it may also be surface-treated with a fatty acid compound, and it may also be used with ordinary coupling agents such as epoxy silanes, amino silanes, and acrylic silanes. , a titanate coupling agent, etc.

Fillers, rubber components, diluents, colorants, pigments, and other flame retardants may be added to the composition of the present invention, if necessary.

Examples of fillers include aluminum oxide, magnesium oxide, calcium carbonate, magnesium carbonate, silica, quartz, kaolin, mica, asbestos, antimony trioxide, and the like.

In addition, dry silica (for example, Aerosil #200 manufactured by Nippon Aerosil ■) is used as an anti-settling agent for fillers, and various antifoaming agents (for example, Shin-Etsu Silicone Co., Ltd., Aerosil #200) are used as antifoaming agents.
KS-603) etc. can be used.

Examples of the rubber component are not particularly limited, and include silicone rubber, carboxyl group-containing butadiene nitrile rubber, styrene-butadiene block copolymer, styrene-isoprene block copolymer, natural rubber, and the like.

Examples of diluents include the above-mentioned diluent containing one epoxy group in one molecule.
In addition to its own low viscosity reactive compounds, cellosolve, butyl cellosolve, butyl cellosolve acetate, carpitol, butyl carpitol, carpitol acetate, γ-butyrolactone, 4-valerolactone, propylene carbonate, xylene, toluene, ethyl acetate, methyl ethyl ketone, Methyl isobutyl ketone, terpineol,
Examples include diacetone alcohol and benzyl alcohol.

Examples of colorants and pigments and flame retardants include titanium dioxide, yellow carbon black, iron black, molybdenum red, navy blue,
Examples include cadmium yellow and triphenyl phosphite.

The composition of the present invention may be mixed by melting at a high temperature as required, or by using a Banbury mixer, kneader, or kneader at a temperature of about room temperature to 150°C.
A method of kneading using a screw or twin screw extruder is applied.

<Example> Hereinafter, the present invention will be specifically explained with reference to Examples.

Examples 1 to 4 Bisphenol A type epoxy resin (Yuka Shell ■ Manufactured by E
P828''), 60 parts by weight of alicyclic epoxy resin (1L Hepoxide 2021'' manufactured by Daicel Aji), and dimethyltetrahydrophthalic anhydride (manufactured by Shin Nihon Rika ■).
0.5 parts by weight of 2,4.6-tris(dimethylaminomethyl)phenol as a curing accelerator was added to 109 parts by weight of M A sex imparting agent and a coupling agent were added and thoroughly dispersed and mixed using a sieve machine to obtain a resin composition.
The mixture was poured into a silicone mold heated to .degree. C., heated at 100.degree. C. for 3 hours, and then cured at 150.degree. C. for 15 hours to obtain each cured product. The flame retardancy of each cured product is UL94
Measured according to the test method. That is, 5X (1/
2) 'X (1/4)' sample with burner diameter (3)
/8)', after standing vertically in a gas of flame height (3/4)' and igniting an indirect flame for 10 seconds, measure the time required for the flame to go out. The same measurement was performed twice in succession on the same sample to determine the average extinguishing time. If the flame is extinguished within 10 seconds, the flame retardant grade is UL-94V-0. Additionally, during this flame retardancy test, the presence or absence of toxic gases such as hydrogen bromide was investigated. Furthermore, using cured product samples with the same shape as those for which flame retardancy was measured, they were left in a heating oven at 230°C, and changes in appearance were observed after one week to examine the heat resistance of each cured product. . The results are shown in Table 1.

As is clear from Table 1, Examples 1 to 4 using hexagonal plate-shaped magnesium hydroxide with an average particle size of 0.6 μm were easily combined with the epoxy resin composition regardless of whether or not surface treatment was performed. It showed good flame retardancy and heat resistance.

Furthermore, even if red phosphorus (a halogen-free flame retardant) and a silane coupling agent are used together, flame retardancy and heat resistance will not be impaired.

In addition, Table 1 shows that Comparative Example 1, in which aluminum hydroxide was used instead of magnesium hydroxide, had poor heat resistance at 230°C.
If left in an atmosphere for one week, the cured product will decompose.

Furthermore, as shown in Table 1, Comparative Example 2 in which magnesium hydroxide was used in combination with decabromodiphenyl oxide, a flame retardant containing a halogen, had slightly inferior heat resistance and generated toxic hydrogen bromide during the test.

In addition, as shown in Table 1, in Comparative Example 3.4, in which a conventional magnesium hydroxide with a large particle size was used, the cured product became crumbly after curing due to poor mixing, resulting in the creation of test pieces for measuring flame retardancy and heat resistance. was not possible.

<Effects of the Invention> According to the present invention, since specific magnesium hydroxide is used as a flame retardant, the magnesium hydroxide is sufficiently mixed in the epoxy resin composition, and a normal cured product can be obtained. Furthermore, the composition of the present invention exhibited sufficient flame retardancy and heat resistance when cured. Also, no toxic gas is generated during combustion.

Claims (1)

[Claims] 100 parts by weight of epoxy resin and an average particle size of 0.6-1.
0μm hexagonal plate-shaped magnesium hydroxide 5-300
A flame retardant resin composition consisting of parts by weight.