JPS62205152A - Flame-retardant epoxy resin composition - Google Patents

Abstract

PURPOSE:The titled composition which has improved electric characteristics such as insulation resistance, breakdown voltage, dielectric constant, etc., and high flame retardance free from poisonous components, obtained by bending a halogen-containing addition type flame-retardant with an allyl group-containing phosphoric ester. CONSTITUTION:(A) 100pts.wt. epoxy resin is blended with (B) 10-50pts.wt. halogen-containing addition type flame-retardant and (C) 5-40pts.wt. allyl group- containing phosphoric ester. Or, the blend is further mixed with (D) 100-230pts. wt. aluminum hydroxide as both a filler and a flame-retardant. Hexabromobenzene, decabromodiphenyl ether or tetrabromobisphenol A is used as the component B. Cresyl phenyl phosphate, xylenyl diphenyl phosphate, etc., is used as the component C.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a flame-retardant epoxy resin composition, and particularly to an epoxy resin composition suitable for sealing and impregnating electrical parts.

BACKGROUND OF THE INVENTION Epoxy resin compositions have been widely used for the purpose of moisture proofing and insulating electrical components such as resistors, capacitors, transformers, motors and diodes. On the other hand, as evidenced by the tightening of UL standards in the United States, the demand for flame retardant properties for these electrical components is increasing, and it is well known that epoxy resin sealants and impregnators are being made flame retardant. It is as follows.

A conventional method for flame retardant epoxy resin compositions that has been commonly used is the use of halogen-containing additive flame retardants, such as perchloropentacyclodecane.

Hexabromobenzene decabromo biphenyl, decabromo biphenyl ether, tetrabromo bisphenol A
, a method of adding and mixing chlorinated paraffin etc. with antimony trioxide added as a flame retardant aid to an epoxy resin, a method of adding and mixing phosphorus or phosphate ester,
Alternatively, a method that uses phosphorus in combination with an inorganic hydroxide such as aluminum hydroxide or molybdenum hydroxide, or an epoxy resin in which both ends of the copolymerization of tetrabromobisphenol A and bisphenol A are converted to glycidyl ether, Methods such as introducing halogen into the resin to make the resin itself flame retardant are used.

Problems to be solved by the invention However, among these, a combination of a halogen-containing additive flame retardant and antimony trioxide has good properties as a sealant for electrical parts, such as flame retardancy and insulation resistance. but,
The toxicity of antimony trioxide and the instability of its supply have recently been pointed out. Additionally, halogen-containing additive flame retardants and antimony trioxide are generally expensive.

On the other hand, in the flame retardant method using phosphorus as the main component, the hygroscopicity of phosphoric acid generated during the cross-talk between phosphorus and the resin component 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 when halogen-containing additive flame retardants are used. Recently, some products have coated phosphorus, especially red phosphorus, with a specific resin to suppress moisture absorption and improve the insulation properties of the resin.
Even so, the insulation resistance is lower than that of resins using halogen-containing additive flame retardants.

In addition, resins using phosphate esters such as tricresyl phosphate, trischloroethyl phosphate, or tri(dichloropropyl) phosphate have high polarity, and the decomposition products of phosphoric acid and metal phosphate Insulation resistance is generally low due to hygroscopic properties such as acids. In addition, this type of phosphoric acid ester often has high volatility and bleeding problems.
To solve this problem, if a phosphoric ester with a large molecular weight is used, the phosphorus content will be low, and a large amount of phosphoric ester will need to be added to provide the desired flame retardancy. The viscosity of the sealant increases and physical properties such as sealing performance decrease.

Epoxy resins containing halogen in their molecular structure have good flame retardancy, but have poor sealing performance.
They have poor electrical properties such as electrical insulation, and are generally expensive.

In addition, in liquid epoxy resin casting material compositions, a casting material with low viscosity is required from the viewpoint of workability, and for this reason, a low-viscosity diluent is usually added to the resin composition.
Addition of this diluent causes a large decrease in the electrical properties of the casting material, especially the insulation resistance, and also causes a decrease in mechanical properties such as sealing performance. Therefore, it is desirable to use such a diluent in the minimum necessary amount.

Epoxy resin sealants are usually used in combination with various fillers in order to improve properties and reduce costs, and in flame-retardant sealants, various hydroxides are used as fillers. However, if a large amount of filler is used to improve flame retardancy, the electrical properties may deteriorate or the viscosity of the sealant may increase, resulting in a decrease in workability.

In view of the above prior art, the present invention has been developed to provide a material that does not contain toxic components such as antimore oxide, has good electrical properties such as insulation resistance, dielectric breakdown voltage, dielectric constant, and dielectric loss, and has low viscosity. The present invention provides a liquid type flame retardant epoxy resin t4ha composition which has good workability and excellent flame retardancy.

Means to Solve the Problems The compositional components imparting flame retardance used in the present invention are a mixture of a halogen-containing additive flame retardant and an allyl group-containing phosphate ester.

Function: Both chlorine-based and bromine-based flame retardants can be used as halogen-containing additive flame retardants, but bromine-based flame retardants have a greater flame retardant effect than chlorine-based ones when added in the same amount; Because of their high decomposition properties, they are less harmful to pollution than brominated aromatic flame retardants such as hexabromobenzene (for example, Nippo Chemical Co., Ltd.'s FR-B) and decabromodiphenyl ether (for example, Nippo Chemical Co., Ltd.'s FR-B). FR-PE (manufactured by Co., Ltd.), tetrabromobisphenol A (for example, Fire Guard 52ooo, manufactured by Yotaikasei Co., Ltd.), and the like can be used. When these brominated aromatic additive flame retardants are used in combination with phosphoric acid esters, they produce a synergistic effect on flame retardant properties. The amount of the brominated aromatic flame retardant added depends on the amount of phosphate ester and filler added, but is 10 to 60 parts by weight, preferably 15 to 30 parts by weight, per 100 parts by weight of the epoxy resin. However, it has the best electrical characteristics and 6z for work seminars. If Blend 7: is less than the above blending range, sufficient flame retardancy will not be obtained, and if it is too large, the mechanical f1 of the epoxy resin will be low.

Next, regarding phosphoric acid esters, each of the f.
The phosphoric acid ester containing Allyl-Juku had good electrical characteristics such as insulation resistance and dielectric breakdown voltage.

Specifically, cresyl diphenyl phosphate-1 (for example, Phosflex # manufactured by Stouffer Japan)
112), xylenyl diphenyl phosphate (for example, Phosflex 59 manufactured by Stouffer Japan)
O),) ligicilenyl phosphate (e.g., Phosflex a179, manufactured by Stouffer Japan), mono(or di)ph, nil di(or mono) isobrobylphenyl phosphate r--1- (e.g., manufactured by Ajinomoto Co., Ltd.) , Rheophos # part), etc. can be used. Since these are all liquids with relatively low viscosity, the combination of flame retardant and diluent (-) lowers the viscosity of the sealing material and improves workability.

However, since this type of phosphoric acid ester is relatively inexpensive, it is possible to reduce the price of the compounded resin. The amount to be added is 5 to 40 parts by weight, preferably 10 to 30 parts by weight, based on 100 parts by weight of the epoxy resin, which is best from the viewpoint of electrical properties and mechanical properties such as sealing performance. If the blending amount is less than the above blending range, sufficient flame retardancy cannot be obtained, and if the blending amount is larger than the above blending range, insulation resistance and mechanical properties will be lowered.

As the filler and flame retardant, hydroxides such as aluminum hydroxide and molybdenum hydroxide can be used, but aluminum hydroxide is the cheapest in terms of cost. In the present invention,
Ordinary aluminum hydroxide (for example, manufactured by Showa Light Metal Co., Ltd.,
]・In addition to Ijirai H-32), a low electrical conductivity type aluminum hydroxide (for example, H-34I manufactured by Showa Light Metal Co., Ltd.) from which ionic impurities have been removed using an ion exchange membrane is used.

In addition, aluminum hydroxide of a type whose surface has been treated with stearic acid, a silicone-based coupling agent, or a titanium-based coupling agent to improve compatibility with resin (for example, H-323 manufactured by Showa Light Metal Co., Ltd.) , H-32S
T, H-32T, etc.) may also be used.

The basic resin formulation of the present invention has an epoxy equivalent of 180 to 190.
bisphenol A type epoxy resin (e.g., Ebicor, manufactured by Yuka Shell Co., Ltd., $828), and a diglycidyl ether of polyglycol (for example, diethylene glycol diglycidyl ether YE, manufactured by Yuka Shell Co., Ltd.) as a diluent.
D205), dihydric alcohol diglycidyl 1-thyl (e.g. Eva, 1.6-quinanediol diglycidyl ether ED603 manufactured by Asahi Denka Co., Ltd.), and the like are used. The amount of these diluents is 10 parts by weight per 100 parts by weight of epoxy resin.
~30 parts is preferred. When a particularly low viscosity composition is required, bisphenol F having an epoxy equivalent of 160 to 180 can be used instead of the above bistubonol A type epoxy resin.
type epoxy resin (for example, manufactured by Tobu Kasei Co., Ltd., YDF1A0
) is used.

Further, the above-mentioned halogen-containing additive flame retardant, phosphoric acid ester, and aluminum hydroxide are added to this. In addition, dry silica (
For example, Aerosil (manufactured by Nippon Aerosil Co., Ltd., $200) and various antifoaming agents (eg, KS-603, manufactured by Shin-Etsu Silicone Co., Ltd.) can be used as the antifoaming agent.

As the curing agent, various acid anhydride curing agents, such as methyltetrahydrophthalic anhydride HN-22 manufactured by Hitachi Chemical Co., Ltd.
00, B-570 or □ also manufactured by Inu Nippon Ink Co., Ltd.
, methylhexahydrophthalic anhydride HN manufactured by Hitachi Chemical Co., Ltd.
-5500, MH-700A also manufactured by Shin Nippon Rika Co., Ltd.
etc. can be used.

The curing agent is used by adding 1 to 6 parts by weight of a curing accelerator to 100 parts by weight of the curing agent. The curing accelerator used is imidazole (for example, 2-ethyl, 4-methylimidazole 2E4MZ manufactured by Shikoku Kasei Co., Ltd.) or
, 4, 61-1), x, dimethylamine methylphenol (for example, TAP manufactured by Hitachi Chemical Co., Ltd.) or 3
Salts of grade amines (for example, UCATl manufactured by Sun Abbott)
02) etc. can be used.

The curing accelerator is appropriately selected depending on the desired curing conditions and pot life conditions. The curing accelerator still affects the electrical properties and adhesive strength of the encapsulant after curing.

Since the mechanical and thermal properties such as the softening point also change, the type and amount of the accelerator to be used are determined experimentally as appropriate. In the present invention, methyl, hexahydrophthalic anhydride (MH-70OA manufactured by Shin Nihon Rika Co., Ltd.) is used as a curing agent.
As a curing accelerator, UCAT10 manufactured by Sun Abbott
2, and imidazole (2E4MZ manufactured by Shikoku Kasei Co., Ltd.)
These were used because they met appropriate curing conditions and pot life conditions, and had excellent electrical, mechanical, and thermal properties.

The epoxy resin composition obtained by blending the above composition,
The properties before and after curing were based on the following items and measurement methods. That is, the viscosity and pot life of the resin composition before curing were measured. The viscosity was measured at 26° using a B-type viscometer at rotor f3.
The viscosity at C was measured. The pot life is the resin composition 1.
This was substituted by measuring the time until the viscosity of 00g in an 80°C oil bath suddenly increases. 80゛C
A pot life of 1 hour at room temperature corresponds to a pot life of about 10 hours at room temperature.

Regarding the resin composition after curing, the electrical properties include insulation resistance (volume resistivity) and 120' of the cured resin.
C2 atmosphere 100 hours pressure shoe test (P
The deterioration of the insulation resistance after the CT test), the dielectric breakdown voltage after curing (3js/pull thickness), the dielectric constant ε, and the dielectric loss 1anδ were measured. These measurement methods were based on Tl5K6911. ε, -δ is 10kl
h, Measured at room temperature. As for thermal properties, the glass transition temperature was measured using a differential scanning calorimeter (DSC). Moreover, the flame retardancy test was measured according to the UL94 test method. In other words, a sample of 6" Measure the time. Perform the same measurement twice in succession on the same sample to find the average flame-out time. If the flame goes out within 10 seconds, the flame retardant grade is UL-94V-0.

In the following Examples, a method for preparing a sealing material resin composition and results of measuring its properties will be described.

Example: 10 parts by weight of diethylene glycol diglycidyl ether (YED205, manufactured by Yuka Shell Co., Ltd.) was added to 80 parts by weight of bisphenol A epoxy resin (Epicoat, manufactured by Yuka Shell Co., Ltd.).
Parts by weight, 10 parts by weight of cresyl diphenyl phosphate (7 Osflex #112 manufactured by Stouffer Japan Co., Ltd.), dry silica (Aerosil #2 manufactured by Nippon Aerosil Co., Ltd.)
00) and 0.1 part by weight of a silicone antifoaming agent (KS603 manufactured by Shin-Etsu Silicone Co., Ltd.) are added, and the mixture is thoroughly stirred and mixed. Furthermore, 25 parts by weight of decaproxy phenyl ether (FR-PE manufactured by Hitachi Chemical Co., Ltd.), aluminum hydroxide (Hijirai H-32 manufactured by Showa Light Metal Co., Ltd.)
100 parts by weight, and low electrical conductivity type aluminum hydroxide (Hisilite H-34I manufactured by Showa Light Metal Co., Ltd.) 40
Parts by weight are added, and the filler and flame retardant are sufficiently dispersed and mixed in the epoxy resin using a three-roll mill to obtain the main ingredient of the sealant composition.

Regarding the curing agent composition, 100 parts by weight of methyltetrahydrophthalic anhydride (MH-700A, manufactured by Shinnihon Rika Co., Ltd.) and 2 parts by weight of a tertiary amine salt (UCATl 02, manufactured by Sun Abbott) as a curing accelerator were added. The mixture is thoroughly stirred and mixed to obtain a curing agent composition.

The resin base composition and curing agent composition obtained as described above were mixed in a ratio of epoxy resin and acid anhydride of 100:8.
5 to 90, that is, the base composition and the curing agent composition are blended at a ratio of 100:31 and mixed by stirring,
A flame-retardant epoxy resin composition is obtained by vacuum defoaming.

The resulting composition was heated for 80'02 hours, followed by 110°C.
to obtain a cured product.

Table 1 shows the compositions of Examples 1 to 3 and Comparative Examples 1 to 3, and Table 2 shows the measurement results of their properties.

As shown in Table 2, the flame retardance of Examples 1 to 7 according to the present invention is at the level of UL94V-0, and even in the insulation properties, which are the most important for electrical component sealing materials, the initial The insulation resistance shows a high value of more than 1015Ω・2 atm at 120″C.

Insulation resistance after 100 hours PCT test is also 1013Ω・m
maintains the above level. On the other hand, as seen in Comparative Example 1, the insulation resistance after the PCT test in the one using red phosphorus was reduced to 3×10 11 Ω·α.

Comparative Examples 2 and 3, 7. Those using a rhodan-containing additive flame retardant and antimony trioxide showed a high insulation resistance of 10 Ω・m or more after the PCT test. As mentioned above, the toxicity of antimony trioxide is a problem.

The dielectric breakdown voltage, ε, tan δ, and glass transition temperature of Examples 1 to 4 are equivalent or higher than those of Comparative Examples 1 to 3, and are at a level that can be used in practical use as a sealing resin for electrical components. .

Effects of the Invention As described in detail above, the present invention provides a non-polluting, unrivaled electrical property, and is also inexpensive.
It is possible to provide a flame-retardant resin for encapsulating electrical parts, and can meet the demands for flame-retardant resins and lower costs, which are expected to become increasingly strict in the future.

Claims (6)

[Claims] (1) Adding a halogen-containing flame retardant to the epoxy resin,
A flame-retardant epoxy resin composition characterized in that it is blended with an allyl group-containing phosphate ester. (2) The flame-retardant epoxy resin composition according to claim 1, wherein the halogen-containing additive flame retardant is hexabromobenzene, decabromodiphenyl ether, or tetrabromobisphenol A. . (3) The allyl group-containing phosphoric ester is cresyl phenyl phosphate, xylenyl diphenyl phosphate, tricylenyl phosphate, monophenyl diisopropylphenyl phosphate, or diphenyl monoisopropylphenyl phosphate. A flame-retardant epoxy resin composition according to claim 1. (4) The flame-retardant epoxy resin composition according to claim 1, wherein 10 to 50 parts by weight of a halogen-containing additive flame retardant is blended with 100 parts by weight of the epoxy resin. (5) The flame-retardant epoxy resin composition according to claim 1, wherein 5 to 40 parts by weight of the allyl group-containing phosphate ester is blended with 100 parts by weight of the epoxy resin. (6) The flame-retardant epoxy resin composition according to claim 1, wherein 100 to 230 parts by weight of aluminum hydroxide is blended as a filler and flame retardant to 100 parts by weight of the epoxy resin. .