JPS6185473A - Resin composition for sealing electrical part - Google Patents

Abstract

PURPOSE:To provide a composition having high sealing adhesivity and high masking power, and curable in a remarkably short time, by compounding a radiation-curable resin composition with plastic microspheres expandable with heat. CONSTITUTION:A resin composition curable with radiation is compounded with plastic microspheres expandable with heat. The resin composition is preferably composed mainly of a prepolymer having polymerizable carbon-carbon double bond and a monomer having polymerizable carbon-carbon double bond. The plastic microsphere is powder having an average particle diameter of 10mu, a bulk density of 0.7 and an expansion temperature of 90-120 deg.C, and prepared by microencapslating isobutane with a copolymer of acrylonitrile and vinylidene chloride.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to a radiation-curable resin composition for encapsulating electrical components, which has a high encapsulation power and a negative effect.

(Industrial Application Field) 1-The resin composition for sealing gas components of the present invention is a radiation-curable sealant, so the curing time is significantly shorter than that of a thermosetting inhibitor. Moreover, even though it is a radial thread) and a hardening type, the sealing adhesive force is high, and the cured sealant also has a smearing force, making it advantageous for sealing unique electrical components. can be used.

(Prior art) Various electrical components are subject to protection, ice g'x,
, sealed with a sealant for rock purposes. Examples include synthetic resin cases such as L1 polybutylene terephthalate resin and noryl resin, such as capacitors and resistor cans, and F2. So-called potting is performed in which an element is placed in a case etc. and hooked with resin.Also, for relays, switches, electronic circuits, etc., the case and terminals in which the confectionery is placed are sealed (sealing). will be carried out.

Sealants used for sealing such electrical parts include:
Hitherto, tβ-forming resins such as epoxy resins have been used, but they have the drawback of taking a long time to cure.

For example, epoxy resin has a heat curing amount of 2~
It takes 3 hours or more, and the room temperature 6il type requires 1 to several days.

For this reason, in recent years, radiation arsenized resins, such as ultraviolet pores, 1L glue, and hardening resins, have come to be used as soil stoppers for such "uniformly exposed" parts. Radiation Lj-based sealant can be cured within a few seconds to tens of seconds, and unlike thermosetting resins, it does not cause pinholes caused by the expansion of air due to the weight t. However, its performance is still inferior to that of epoxy resin sealants, and its uses are limited.

(Problems to be Solved by the Invention) In particular, the following two points are major drawbacks of radiation-curable sealants compared to thermosetting T1 sealants such as epoxy resins.

(,) Sealed 21: Poor adhesion to the body and electrical parts.

(b) Unlike heat-cured encapsulants, a large amount of pigment cannot be added, so the cured encapsulant lacks negative effect.

The present invention aims to improve the above-mentioned drawbacks of radiation-curable encapsulants.

(Means for solving the problems) In order to solve the above problems, the inventors have proposed
As a result of extensive research, it was discovered that this objective could be easily achieved by incorporating plastic microspheres that expand with heat into a radiation-curable sealant, and the present invention was achieved.

That is, the resin composition for encapsulating electrical components of the present invention is a composition obtained by blending plastic microspheres that expand with heat into a resin composition that can be sintered by radiation exposure.

Ratio 44'J' rvg in the composition of the present invention 3
．． ] As a resin composition that can be converted into a 3-layer resin composition, 1.1
Although it is possible to use a variety of different types, particularly preferable ones include a prepolymer having a sjC water-carbon double bond, and a monomer having a sjC water-carbon double bond as the main components. You can open what you want.

Examples of prepolymers having ≦9 divalent bonds on the polymerizable carbon include L unsaturated polyesters, and radical monomerizable functional groups such as acroyl groups, methacroyl groups, allyl groups, and vinyl groups. Various oligomers having one or more oligomers are available. Furthermore, the same oligomers include acrylic acid or methacrylic acid additives such as epoxy resin, urethane resin, terminal hydroxy polybutanoene and terminal hydroxy polyester, terminal carboxy polybutanoene and terminal carboxy polyester 2- Examples include hydroxyethyl acrylate or 2-hydroxyethyl methacrylate adducts.

Since these unsaturated polyesters and oligomers are commercially available under various trade names, these commercially available products can be used as appropriate. One type of such prepolymers may be used alone, or two or more types may be used in combination as appropriate.

Furthermore, examples of monomers having polymerizable carbon-carbon double bonds include styrene, styrene derivatives such as vinyltoluene, various esters of acrylic acid or methacrylic acid, diallyl phthalate, triallyl isocyanurate, and vinyl acetate. etc. can be mentioned. These monomers may be used alone or in combination of two or more.

The resin composition curable (by radiation irradiation) of the present invention includes:
If necessary, a photopolymerization initiator such as benzoin, benzoin ether, benzophenone, or diphenyl sulfide is added. Moreover, various fillers, thixotropy imparting agents, pigments, etc. can be added to the curable resin composition as necessary.

The most important feature of the resin composition for encapsulating electrical components of the present invention is that it contains plastic microscopic 741 spheres that expand when heated. The plastic microspheres can be effectively used in the present invention as long as they expand with heat.

Plastic microspheres that expand with such heat can be killed by, for example, microencapsulating low-boiling point hydrocarbons with individual plastics, and by heating them, gases such as low-boiling point hydrocarbons can be killed. The expansion causes the microspheres to expand. Since this type of plastic microspheres are already commercially available under trade names such as Expancel (manufactured by Nippon Philite Co., Ltd.), the present invention can be easily carried out using such commercial products. . The above Expancel is microencapsulated isobutane using a copolymer of acrylonitrile and vinylidene chloride, has an average particle size of 10μ, a bulk specific gravity of 0.7, and an expansion temperature range of 90 to 120°C. with powder,
The radiation of the present invention can be easily dispersed into radiation-curable resin compositions.

The blending amount of the plastic microspheres in the present invention varies depending on the resin composition and the type of microspheres, etc. - Although it cannot be generally specified, it is usually 0.1% of the resin composition. ~several i%.

In order to seal an electrical component using the sealing resin composition of the present invention, the electrical component is sealed with the resin composition and then cured by radiation irradiation. It is also possible to further perform a heat curing treatment afterwards.

(Operations and Effects of the Invention) Generally, when an electrical component is sealed using a radiation-curing sealant, the tensile strength of the terminal and the peel strength between the sealant and the case are lower than those of the epoxy sealant. The sealant is weaker than the case where the sealant is sealed using a sealant, etc., and peeling between the case and the sealant is likely to occur even in a heat cycle test. The main reason for this is
It is thought that this is due to the fact that radiation-curable sealants have larger curing shrinkage than epoxy resin sealants and the like. In other words, while the curing shrinkage of epoxy resin is 1 to 2%,
Radiation IIi! Since the curing shrinkage of the curable sealant is 3 to 5 inches, a large tensile stress is generated between the case and the sealant, which weakens the adhesive strength.

However, since the sealant composition of the present invention contains plastic microspheres that expand due to heat, when the encapsulant begins to harden due to radiation irradiation, the reaction heat causes the microspheres to expand. This makes it possible to suppress the generation of internal stress due to curing shrinkage, and effectively prevent a decrease in adhesive strength.

In addition, with thermosetting sealants such as epoxy sealants, even if a relatively large amount of pigment is added, there is no adverse effect on the curing speed or cured physical properties. Can give you secret power. However, radiation-cured encapsulants,
In particular, UV-curable encapsulants, due to their curing mechanism,
There are restrictions on the addition of pigments. That is, if the amount of pigment added is large, ultraviolet rays will not be transmitted to the inside, resulting in poor curing, worsening the electrical characteristics of the element, and lowering the sealing adhesive strength.

Therefore, the ultraviolet curable encapsulant can only be colored to such an extent that ultraviolet rays can pass through, and it is insufficient to shade the inside of the electrical component body.

However, the encapsulating resin composition of the present invention is transparent before curing, allows ultraviolet rays to pass through it well, and can be effectively cured to the inside. The cured product becomes white and opaque and has a shadowy effect.

(Examples, etc.) Next, the present invention will be further explained in detail by giving examples and test examples.

Example 1 An ultraviolet curable resin composition (hereinafter, this composition will be referred to as "composition A") having the following composition was prepared.

Epoxy 5P-150970 parts by weight 2-hydroxyethyl acrylate 30
1 Benzin butyl ether 2I Note) Dishes: Trade name of epoxy acrylate manufactured by Showa Kobunshi Co., Ltd. To the above composition A, add Expancel (trade name, Philite Co., Ltd.) at a ratio of 0.3 to 3 A &I fat composition for sealing electrical parts was obtained by blending in various ratios in terms of weight and weight.

Example 2 An ultraviolet curable resin composition (hereinafter, this composition will be referred to as "composition B") having the following composition was prepared.

Aloex M-1100160 Jukenbu Phenoxyethyl Acrylate 40 l Benzoin Butyl Ether 21 Add Expancel (trade name, Philite Co., Ltd.) to the above composition B at a rate of 0.3 to Composition B.
A resin composition for encapsulating electrical components was obtained by blending the resin compositions in various proportions ranging from 31111 L% to 31111 L%.

Test Example 1 As shown in Figure 1, the inside dimensions are class X width x height 15 cm x 5
m x 5 ym, thickness 0.5 vr:
1 polybutylene terephthalate case 1, lower X1
Insert the hair-like bends of the iron plate piece 4, which is made by bending u into a wing shape from side to side, into sections 4' and 4', overlay the polyethylene terephthalate film 2 on top of the wing section, and then empty the film 2. On top of this, various UV-curable encapsulants 3 in which Expancel was added in various proportions to Composition A used in Example 1 or Composition B used in Example 2 were added to a depth of lfi. The sealant was cured by irradiating it with ultraviolet light. The output power is 80 W/c for ultraviolet irradiation! The conditions were irradiation under a metal halide lamp of n for 20 seconds at 10α. The case 1, in which the sealant had been cured by ultraviolet irradiation, and the iron plate piece 4 were stretched to examine the strength at which the cured sealant and the case would peel off.

The results are shown in FIG. 2, and the peel strength reached its maximum value when the amount of Expancel added was 1 to 2 weight. When the amount added exceeded 2% by weight, the strength gradually decreased. This is thought to be because if there is too much Expancel, the cured resin becomes spongy and stress concentration on the adhesive surface is likely to occur during the peel test.

In addition, when Expancel was not added, the cured encapsulant was transparent and the inside of the element could be seen through, but when the amount of Expancel added was 0.5 times or more, the cured encapsulant It became white and opaque, and the inside of the element could not be seen through at all.

Test Example 2 The specific gravity before and after curing was measured by the pycnometer method for the above composition A, composition B, and each composition (sealant) in which 1% by weight of Expancel was added to each of these compositions. . The results are shown in Table 1.

In addition, the test piece of the cured product was coated with a mold release agent and had a diameter of 50 m.
After injecting the sealant to a thickness of 11tII into the dish and curing it by irradiating it with ultraviolet rays under the same conditions as in Test Example 1,
Peel off the cured product from the plate and cut it with a diamond cutter for 10 minutes.
It was cut into small pieces of W square and used for measurement of specific gravity.

Table 1 As is clear from Table 1, composition person and composition B are:
When Expancel was not added, curing shrinkage of 4.3% and 3.7% occurred, respectively. In contrast, when 1% Expancel was added to these compositions, the opposite expansions occurred by 3.8 inches and 2.0 inches, respectively. It is thought that the expansion during curing due to the addition of Expancel contributes to the improvement of adhesive strength.

[Brief explanation of the drawing]

FIG. 1 is a drawing showing a sealed capsule used to test the sealing adhesive strength of a sealing resin composition, and A is a front view thereof, B is a side view thereof, and C is a plan view thereof. . Each symbol in the figure indicates the following. 1... Polybutylene terephthalate case, 2...
Polyethylene terephthalate film, 3... Resin composition for sealing, 4... Iron plate piece for tensile strength, 4'... Feather-shaped bent portion. Figure 1 Etas Bancel Lacquer Sword 0 Rate (vs. Composition Saiminari tZ) Procedure
Amendment, correction (method) % formula % 1. Indication of the case 1982 Patent Application No. 206139 2 Name of the invention Name of resin composition for sealing electrical parts Nippon Kasei Co., Ltd. 6. Subject of amendment (1) Details Column 7 of "Brief explanation of drawings" of the document, contents of amendment (as attached) Contents of amendment (1) The following statement is inserted next to line 5 of page 14 of the specification. yeah

Claims (1)

[Claims] 1) A resin composition for encapsulating electrical components, which is made by blending plastic microspheres that expand with heat into a resin composition that can be cured by radiation exposure.