JPH0610245B2 - Manufacturing method of electrically insulating cast products - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a method for producing an electrically insulating casting. More specifically, the present invention relates to a method for producing an electrically insulative casting product which is highly flexible, tough, and excellent in thermal shock resistance.

<Prior Art> Currently, polymer materials such as phenol resin, silicone resin, epoxy resin, and polyimide resin are used as electrical insulating materials. Of these, phenolic resins have problems in reliability and fluidity. Also, the silicone resin is
There is a drawback that the adhesive strength to the adherend is low. Although the polyimide resin has good heat resistance, it requires a high temperature of 250 ° C. or higher for curing.

Epoxy resins are widely used in the electric and electronic fields because they have excellent adhesiveness, chemical resistance, durability, and electrical insulation properties as compared with other materials. However, since the epoxy resin is hard and brittle as it is, various flexibility-imparting agents are used for the purpose of improving impact resistance, improving crack resistance against thermal shock, and reducing internal strain due to curing shrinkage. Often.

As the flexibility-imparting agent for the epoxy resin cured product, a non-reactive flexibility-imparting agent such as a plasticizer or a non-epoxy-based reactivity flexibility-imparting agent such as polythiol is used. However, when the plasticizer is blended with the epoxy resin, the plasticizer oozes out after a long time and causes contamination.

<Problems to be Solved by the Invention> When a polythiol such as a polycarbide polymer is used as a flexibility-imparting agent, by changing the mixing amount of the polysulfide polymer, an appropriate flexibility depending on the purpose can be obtained. A certain epoxy resin cured product can be obtained. However, since the polysulfide polymer has a unique mercaptan odor, when the epoxy resin composition containing the polysulfide polymer is heat-cured, a mercaptan odor derived from the polysulfide polymer is generated, so that the use tends to be avoided. .

As a result of intensive studies on the method for producing an electrically insulative cast product, the present inventors have included a bisphenol skeleton and a polysulfide skeleton, and a modified epoxy resin in which both end groups are epoxy groups, and an acid anhydride. When the mixture containing as a main component is poured into a mold containing an article to be insulated and cured by heating, the resulting electrically insulating cast product has good thermal shock resistance and no mercaptan odor. And has reached the present invention.

<Means for Solving Problems> The present invention has the following configurations.

A method for producing a cast product having an electric insulating layer excellent in thermal shock resistance, comprising: (A) a modified epoxy resin containing a bisphenol skeleton and a polysulfide skeleton, and having both end groups being epoxy groups, and (B) an acid. A method comprising injecting a mixture containing an anhydride as a main component into a mold containing an article to be insulated and curing the mixture by heating.

The modified epoxy resin in the present invention is an epoxy resin in which a polysulfide skeleton is introduced into an epoxy resin having a bisphenol skeleton.

The bisphenol skeleton of the modified epoxy resin in the present invention is, for example, bisphenol A, bisphenol AD,
It has the same molecular structure as halogenated bisphenol A, bisphenol F, and halogenated bisphenol F.

The polysulfide skeleton of the modified epoxy resin in the present invention is represented by the general formula —ROR′OR—Sx (wherein R and R ′ are alkyl groups having 1 to 4 carbon atoms, and the average of x is 1 to 3). Be done.

Further, preferred polysulfide skeleton of the modified epoxy resin in the present invention is a _{-C 2 H 4 OCH 2 OC 2} H 4 -Sx- ( Note that the average of x is 1.5 to 2.5).

The modified epoxy resin in the present invention is produced, for example, by reacting an epoxy resin having a bisphenol skeleton with a substance having a polysulfide skeleton. The modified epoxy resin in the present invention is preferably produced by a method of reacting a substance having a polysulfide skeleton, for example, a polysulfide polymer with a bisphenol type epoxy resin in a state where the bisphenol type epoxy resin is in an excessive amount. The modified epoxy resin in the present invention can be produced by a method of using a solvent such as toluene or a method of using a catalyst such as a tertiary amine, or a method of reacting without a solvent or without a catalyst. The modified epoxy resin produced can also be used in the present invention.

The polymerization ratio of the bisphenol skeleton and the polysulfide skeleton of the modified epoxy resin in the present invention is changed depending on the purpose, but when a relatively soft cured product is intended, a large amount of the polysulfide skeleton and a relatively hard cured product are intended. Reduces the polysulfide skeleton. Generally, it is preferable to control the weight ratio of the polysulfide skeleton in the range of 5% to 75%. If the weight ratio of the polysulfide skeleton exceeds 75%, the cured product becomes soft and the strength decreases, which is not preferable. Further, if the weight ratio of the polysulfide skeleton is less than 5%, the flexibility of the cured product decreases and cracks are likely to occur, which is not preferable.

In the modified epoxy resin according to the present invention, the weight ratio of the bisphenol skeleton to the polysulfide skeleton can be controlled by appropriately selecting the molecular weights of the substance having the polysulfide skeleton as the raw material and the bisphenol type epoxy resin. Further, the weight ratio of the bisphenol skeleton to the polysulfide skeleton can be controlled by selecting the reaction ratio of the substance having a polysulfide skeleton and the bisphenol type epoxy resin.

In the insulator composition used in the method of the present invention, an acid anhydride is blended together with the modified epoxy resin. Examples of the acid anhydride compounded in the present invention include phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, ethylene glycol bistrimellitate, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, endomethylenetetrahydro. Phthalic anhydride, methylendomethylenetetrahydrophthalic anhydride, methylbutenyltetrahydrophthalic anhydride, dodecenylsuccinic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, succinic anhydride, methylcyclohexenedicarboxylic anhydride, alkylstyrene Examples thereof include maleic anhydride copolymer, chlorendic anhydride, and polyazelaic anhydride.

In the present invention, the compounding amount of the acid anhydride varies depending on the kind of the acid anhydride, but is usually 15 to 100 parts by weight based on 100 parts by weight of the modified epoxy resin.

In the present invention, a curing accelerator can be blended together.
The preferred blending amount of the curing accelerator is modified epoxy resin 10
It is 0.1 to 3.0 parts by weight with respect to 0 parts by weight.

Examples of the curing accelerator used in the present invention include N,
N, N ', N'-tetramethylhexamethylenediamine, piperidine, benzyldimethylamine, dimethylaminomethylphenol, 2,4,6-tris (dimethylaminomethyl) phenol, 2-ethyl-4-methylimidazole, triphenyl Phosphine, acetylacetenate metal salt, tin octylate, triethanolamine titanate, amine imide, zinc caprylate, DBU,
Examples include chromium tricarboxylate and the like.

The insulator composition used in the method of the present invention is mainly composed of a modified epoxy resin having a bisphenol skeleton and a polysulfide skeleton and both end groups being an epoxy resin, and an acid anhydride. Alternatively, a small amount of an affinity polymer can be added.

Further, in the insulator composition used in the method of the present invention, if necessary, zinc dust, aluminum powder, carbon black, glass fiber, carbon fiber, aramid fiber,
Titanium oxide, iron oxide, silica, quartz powder, talc, kaolin, calcium carbonate, bentonite, mica, silica sand, clay, wollastonite, polyethylene powder, cyanine blue, chrome zinc, nickel slag, aluminum hydroxide, alumina, stearic acid Further, a filler such as zinc stearate, a filler, a pigment, a reinforcing material, a defoaming agent, a molding lubricant, a release agent, a flow control agent, a flame retardant and the like can be added.

In the electrically insulating casting and manufacturing method of the present invention, the article to be insulated is also placed in a mold, and the insulating composition described above is injected into the mold. Then, the insulating composition is heated and cured, and taken out from the mold.

<Example> Next, the present invention will be described with reference to Synthesis Examples, Examples, and Comparative Examples.

Synthesis Example 1 Bisphenol A was added to a 1-liter separable flask.
Type epoxy resin ("Adeka Resin E" manufactured by Asahi Denka Co., Ltd.)
P-4100 ") and 200 g of polysulfide polymer (" Thiocol LP-3 "manufactured by Toray Thiokol Co., Ltd.) 1
00 g was added and the mixture was stirred at room temperature for 15 minutes. In addition, 2,
After adding 0.05 g of 4,6-tris (dimethylaminomethyl) phenol and stirring for 1 hour and leaving it at room temperature for 24 hours, the polysulfide polymer was entirely bisphenol A.
It was confirmed that it was reacted with the epoxy resin. At this time, the epoxy equivalent is 344 and the viscosity is 640 poise (25
C.), and the reaction product had no mercaptan odor.

Example 1 A method for producing a test piece and a method for measuring thermal shock resistance are JIS
C 2105 (1979) “Test method for solvent-free liquid resin for electrical insulation” (24) [crackability test].

To 100 parts by weight of the epoxy resin of Synthesis Example 1, 42 parts by weight of methyltetrahydrophthalic anhydride and 1 part by weight of 2,4,6-tris (dimethylaminomethyl) phenol were mixed, and a spring washer No. 2 12S was put. After pouring over a flat bottom having an inner diameter of 60 mm and heating and curing at 100 ° C. for 2 hours, it was further heated at 150 ° C. for 4 hours. The test piece was subjected to a thermal cycle test to confirm the presence or absence of cracks for each cycle. The results are summarized in Table 1. As shown in Table 1, cracks were generated at cycle stage "6" (low temperature condition: -55 ° C, high temperature condition: 130 ° C). Comparative Example 1 described below
Compared with, cracks did not occur even under severe conditions, and thermal shock resistance was good.

Example 2 In Example 1, methyltetravitrophthalic anhydride 4
The thermal shock resistance was measured in the same manner as in Example 1 except that 68 parts by weight of methylhexahydrophthalic anhydride was used instead of 2 parts by weight. The results are summarized in Table 1. As shown in Table 1, cycle stage "6" (low temperature condition is -55
Cracks occurred at ℃ and high temperature of 130 ℃. As compared with Comparative Example 2 described later, cracks did not occur even under severe conditions, and the thermal shock resistance was good.

Example 3 In Example 1, methyltetrahydrophthalic anhydride 4
The thermal shock resistance was measured in the same manner as in Example 1 except that 75 parts by weight of dodecenyl succinic anhydride was used instead of 2 parts by weight. The results are summarized in Table 1. As shown in Table 1, no cracks were generated at the cycle stage "6" (low temperature condition: -55 ° C, high temperature condition: 130 ° C), and the thermal shock resistance was good.

Comparative Example 1 100 parts by weight of a bisphenol A type epoxy resin ("Adeka Resin EP-4100" manufactured by Asahi Denka Co., Ltd.), 79 parts by weight of methyltetrahydrophthalic anhydride and 2,4,6
1 part by weight of tris (dimethylaminomethyl) phenol was mixed and the thermal shock resistance was measured in the same manner as in Example 1. The results are summarized in Table 1. As shown in Table 1, cracks occurred at the cycle stage “1” (-10 ° C. under the low temperature condition and 105 ° C. under the high temperature condition).

Comparative Example 2 100 parts by weight of a bisphenol A type epoxy resin (“Adeka Resin EP-4100” manufactured by Asahi Denka Co., Ltd.), 85 parts by weight of methylhexahydrophthalic anhydride and 2,4,6
1 part by weight of tris (dimethylaminomethyl) phenol was mixed and the thermal shock resistance was measured in the same manner as in Example 1. The results are summarized in Table 1. As shown in Table 1, cracks occurred at the cycle stage “1” (-10 ° C. under the low temperature condition and 105 ° C. under the high temperature condition).

Synthesis Example 2 Bisphenol A was added to a 1-liter separable flask.
Type epoxy resin ("Adeka Resin E" manufactured by Asahi Denka Co., Ltd.)
P-4100 ") 200 g and a polysulfide polymer (Thiocol LP-3" manufactured by Toray Thiokol Ltd.) 10
0 g was added and the mixture was stirred at room temperature for 15 minutes. Furthermore, 2, 4,
Add 6-tris (dimethylaminomethyl) phenol to 0.
03 g was added and stirred for 1 hour. After being left at room temperature for 24 hours, all the polysulfide polymer was bisphenol A.
It was confirmed that it was reacted with the epoxy resin. At this time, the epoxy equivalent is 595 and the viscosity is 2000 poise (2
5 ° C.), and the reaction product had no mercaptan odor.

Example 4 100 parts by weight of the epoxy resin of Synthesis Example 2 was mixed with 27 parts by weight of methyltetrahydrophthalic anhydride and 1 part by weight of 2,4,6-tris (dimethylaminomethyl) phenol, and the same as in Example 1. The thermal shock resistance was measured. The results are summarized in Table 2. As shown in Table 2, cycle stage “7” (low temperature condition: −55 ° C., high temperature condition: 15)
Cracks occurred at 0 ° C. Cracks did not occur even under severe conditions, and thermal shock resistance was good.

Synthesis Example 3 A 1 liter separable flask was charged with a polysulfide polymer ("Thiocol LP-" manufactured by Toray Thiokol Co., Ltd.).
3 ") and 93 g of bisphenol F type epoxy resin (" Adeka Resin EP-4900 "manufactured by Asahi Denka Co., Ltd.)
65 g was put and stirred at room temperature for 10 minutes. Furthermore, 2, 4,
Add 6-tris (dimethylaminomethyl) phenol to 0.
05 g was added and stirred for 1 hour. After being left at room temperature for 24 hours, the polysulfide polymer was completely bisphenol F.
It was confirmed that it was reacted with the epoxy resin. At this time, the epoxy equivalent is 328 and the viscosity is 270 poise (25
C.), and the reaction product had no mercaptan odor.

Example 5 100 parts by weight of the epoxy resin of Synthesis Example 3 was mixed with 42 parts by weight of methylterolahydrophthalic anhydride and 1 part by weight of 2,4,6-tris (dimethylaminomethyl) phenol, and the same as in Example 1. Then, the thermal shock resistance was measured. The results are summarized in Table 2. As shown in Table 2, cycle stage “6” (low temperature condition: −55 ° C., high temperature condition: 13)
Cracks occurred at 0 ° C. As compared with Comparative Example 3 described later, cracks did not occur even under severe conditions, and the thermal shock resistance was good.

Comparative Example 3 100 parts by weight of a bisphenol F type epoxy resin (“Adeka Resin EP-4900” manufactured by Asahi Denka Co., Ltd.), 79 parts by weight of methyltetrahydrophthalic anhydride and 2,4,6
1 part by weight of tris (dimethylaminomethyl) phenol was mixed and the thermal shock resistance was measured in the same manner as in Example 1. The results are summarized in Table 2. As shown in Table 2, cracks occurred in the cycle stage “2” (low temperature condition: −20 ° C., high temperature condition: 105 ° C.).

Comparative Example 4 67 parts by weight of a bisphenol A type epoxy resin (“Adeka Resin EP-4100” manufactured by Asahi Denka Kogyo Co., Ltd.), 42 parts by weight of methyltetrahydrophthalic anhydride and a polysulfide polymer (“Thiocol LP- manufactured by Toray Thiocole”).
3 ″) 33 parts by weight and 2,4,6-tris (dimethylaminomethyl) phenol 1 part by weight were mixed and the thermal shock resistance was measured in the same manner as in Example 1. The results are summarized in Table 2. As shown in Table 2, cracks occurred at the cycle stage "6" (low temperature condition: -55 ° C, high temperature condition: 130 ° C). Although cracks did not occur even under severe conditions and the thermal shock resistance was good, mercaptan odor was generated by the polysulfide polymer during heat curing.

<Effects of the Invention> (1) Since the insulator composition used for the electrically insulating cast product manufactured by the method of the present invention contains an epoxy resin having a polysulfide skeleton as a main component, it has thermal shock resistance and chemical resistance. Has excellent wear resistance and durability.

(2) Since the insulator composition used for the electrically insulating cast product manufactured by the method of the present invention does not contain a component having a mercaptan odor, its use is not limited by the odor.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location H01B 3/40 9059-5G

Claims (2)

[Claims] 1. A method for producing a cast product having an electric insulating layer having excellent thermal shock resistance, comprising: (A) a modified epoxy resin containing a bisphenol skeleton and a polysulfide skeleton, and having both end groups being epoxy groups. , (B) a mixture containing an acid anhydride as a main component is poured into a mold containing an article to be insulated and cured by heating. 2. The method for producing a cast product according to claim 1, wherein the weight ratio of the polysulfide skeleton in the modified epoxy resin is 5 to 75%.