JPS5812897B2 - Translucent epoxy resin composition - Google Patents

Description

[Detailed description of the invention] The present invention relates to novel translucent epoxy resin compositions.

More specifically, (5) Epoxy equivalent: 300 to 1000
(B) a cycloaliphatic epoxy resin with an epoxy light intensity of 100 to 300, (C) a polybasic carboxylic acid anhydride, and (D) a filler with a diameter:length ratio of 1:2. A transparent material made of glass fiber in the range of 500 to 500, and characterized in that the proportion of 0) to the total amount of glass, (B), (C) and low is 10 to 50% (wt%, the same shall apply hereinafter). The present invention relates to a translucent epoxy resin composition with excellent properties, impregnability, hardness, and crack resistance.

In general, acid anhydride-cured epoxy resin compositions have excellent mechanical and electrical properties and moisture resistance, and are therefore widely used as materials for embedding electronic parts or casting electrical equipment.

For these electronic or electrical parts, transparent cured resin is required, such as the sealing material for light emitting diodes, and parts that require a transparent cured resin, such as those for embedding, and those that require a cured resin that is such that abnormalities in the implanted parts can be easily seen with the naked eye. There are applications where a relatively transparent cured resin product is required.

In addition to transparency, the latter is due to the impregnation properties of the resin composition, as well as the stress caused by tightening the iron core during installation as a cast product, due to the impregnated insulation of embedded parts such as magnetic coils. An epoxy resin composition is required that is hard enough not to deform due to the vibrations of the coil during operation or external forces, and has sufficient crack resistance against temperature cycles and heat shock during use. It is said that

Conventionally, for this type of application, epoxy resin compositions containing no filler or epoxy resin compositions containing colorless and transparent glass powder as a filler have often been used due to the requirement for transparency. has the disadvantage that it cannot be changed into a hard cured product and cracks easily occur.
It was difficult to use it for large cast parts.

In the latter case, the hardness and crack resistance improve as the content of glass powder increases, but there are disadvantages in that the visibility of the embedded part decreases and the impregnability decreases.

At that time, if the content of glass powder is low, the opposite phenomenon to the above will occur, and the sedimentation of glass powder will become noticeable.
It cannot be put to practical use.

Therefore, the present inventors conducted various studies to improve the above-mentioned problems, and found that (A) a bisphenol A-based epoxy resin with an epoxy equivalent of 300 to 1,000, and (B) a cyclic epoxy resin with an epoxy equivalent of 100 to 300 as epoxy resins. Aliphatic epoxy resin, (C) polybasic carboxylic acid anhydride as a curing agent, (D) as a filler with a diameter:length ratio of 1:2 to
Consisting of glass fibers in the range of 500, (A), (B),
(The ratio of (D) to the total amount of q and (D) is 10
Transparency, using an epoxy resin composition that is ~50%
The inventors have discovered that it is possible to provide a cured epoxy resin with excellent impregnability, hardness, and crack resistance, leading to the completion of the present invention.

As the epoxy resin used in the present invention, a bisphenol A-based epoxy resin and a cycloaliphatic epoxy resin are used.

Bisphenol A-based epoxy resins have excellent crack resistance and liquefy at temperatures below 100°C, so they have an epoxy equivalent of 300 to 1000, which is convenient for casting work.
are preferably used.

On the other hand, as the cycloaliphatic epoxy resin, one preferably used is one having an epoxy equivalent of 100 to 300, which has excellent transparency, low viscosity, and excellent impregnation and casting operations.

The blending ratio of these two types of epoxy resins is preferably 10 to 100 parts of the cycloaliphatic epoxy resin, with the cycloaliphatic epoxy resin being 10 parts per 100 parts (by weight, the same applies hereinafter) of the bisphenol A-based epoxy resin. If it is less than 100 parts, the transparency will be low, and if it is more than 100 parts, the crack resistance will be poor.

In addition, as an epoxy resin component, the transparency is poor when using only other bisphenol A epoxy resins, which have low viscosity and excellent impregnating and casting properties, and when using only cycloaliphatic epoxy resins, the resistance is poor. Both types of epoxy resins are poor in crack resistance, and the sedimentation of the filler is significant during curing, making them unsuitable for practical use.By using the two types of epoxy resins in combination, these drawbacks can be eliminated.

Next, the glass filler used in the present invention will be described.

Glass, which is generally used as a filler, has a refractive index within the range of 1.45 to 1.65 at room temperature, and a material with a low alkali content is preferably used, and the particle shape is spherical, balloon, or manufactured by pulverization. irregularly shaped particles are used.

However, when spherical or irregularly shaped particles are used as a filler, sedimentation during curing is significant, while when balloons are used, the transparency of the cured product is significantly reduced.

Furthermore, particles of these shapes accumulate on the surface of an object to be impregnated, such as a coil, and have the disadvantage that they impair the impregnability of the resin component.

In the present invention, the glass filler has a diameter:length ratio in the range of 1:2 to 500, and a diameter of 5 to 1.
5μ glass fibers are preferably used.

In this case, if the length:diameter ratio is smaller than 2, the inclusion property will be reduced and sedimentation during curing will be noticeable, as is the case when irregularly shaped particles are used. A ratio greater than 500 has the disadvantage that the viscosity of the composition becomes too high, making impregnation and casting operations difficult.

Furthermore, the filling rate of glass fibers (component D) in the present invention includes epoxy resin (components A and B), curing agent (C
1 for the total amount of component) and Gara fiber (component D)
It is preferably from 0 to 50%; if it is less than this, the crack resistance and hardness will decrease, and if it is less than this, the transparency and impregnability will decrease, which is not preferred.

Note that a filler in which the glass fibers are previously treated with a silane-based or chromium-based coupling agent has the advantage of improving adhesion to the polymer phase and improving the moisture resistance of the molded part.

As the curing agent, almost all polybasic carboxylic acid anhydrides can be used, but those that do not become darkly colored by the curing reaction are particularly preferred.

Specific examples include phthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride,
Examples include hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, trimellitic anhydride, pyromellitic anhydride, and mixtures thereof.

Examples of the curing accelerator include tertiary amines, metal complex salts of amines, and metal salts of organic acids.

Next, the translucent epoxy resin composition of the present invention will be explained with reference to Examples and Comparative Examples.

Examples 1 to 7 Epicote 836 and Epicote 100 as bisphenol A epoxy resins with epoxy equivalents of 300 to 1000
Araldite CY183, Araldite XB2793 (manufactured by Ciba Geigy), Epotherm CE-600, Epotherm CE- 300 (manufactured by Mitsubishi Chemical Industries, Ltd.), Chinsonox 221 (manufactured by Chisso Corporation), and Araldite HT903 as a curing agent.
PFI3-101 (manufactured by Ciba Geigy) was surface-treated as a glass filler (fiber length 20-100).
Resin compositions as shown in Table 1 were prepared using the following resin compositions, each having a diameter of 9 μm (manufactured by Nitto Boseki Co., Ltd.).

Note that stirring was performed under reduced pressure at 130° C. for 20 minutes.

Comparative Examples 1 to 3 Bisphenol A-based epoxy resins Epicote 828 and Epicote 834 were used as epoxy resins, Araldite CY183 was used as a cycloaliphatic epoxy resin, Araldite HT903 was used as a hardening agent, and PFB-101 was used as a glass fiber filler. Resin compositions as shown in Table 1 were prepared using BDMA (benzyldimethylamine) as a curing accelerator.

The mixture was stirred under reduced pressure at 90° C. for 20 minutes.

Examples 8 to 11 Araldite B and Araldite as epoxy resins}
Araldite HT 90 with CY183 as curing agent
06, which was surface-treated with 3 as a glass fiber filler.
HB830A (fiber length 3mm, diameter 9μ, manufactured by Asahi Fiberglass Co., Ltd.) and PFA-101 (fiber length 20~
100μ, diameter 9μ, manufactured by Nitto Boseki Co., Ltd.)
Resin compositions as shown in the table were prepared.

Stirring was carried out under reduced pressure at 130° C. for 20 minutes.

Example 12 PFA~001 (fiber length 20~100) without surface treatment was used in place of the glass fiber filler used in Example 1.
Resin compositions as shown in Table 2 were prepared using a resin composition having a diameter of 9μ (manufactured by Nitto Boseki Co., Ltd.).

Stirring was carried out under reduced pressure at 130° C. for 20 minutes.

Comparative Examples 4 to 5 Powdered glass fiber (ball 3) was used instead of glass fiber as a filler.
000CP-0 1 (manufactured by Toshiba Ballotini Corporation) or P=325 (manufactured by Asahi Fiberglass Corporation), which is an irregularly shaped glass powder produced by pulverization, was used to create a resin composition as shown in Table 2. was prepared.

Stirring was carried out under reduced pressure at 90° C. for 20 minutes.

Comparative Example 6 A resin composition as shown in Table 2 was prepared using 6PA-401 (manufactured by Nittobo Co., Ltd.), which is glass fiber with a fiber length of 6 mm and a diameter of 9 μm, as a glass fiber filler.

Stirring was carried out under reduced pressure at 130° C. for 20 minutes.

Comparative Examples 7-8 The above-mentioned PFA-10 was used as the glass fiber filler (component D)
Using No. 1, resin compositions having filling rates of 10% or less and 50% or more based on the total amount as shown in Table 2 were prepared.

Stirring was carried out under reduced pressure at 130° C. for 20 minutes.

Examples 13-15 Benzyldimethylamine (BDM) as a curing accelerator
A), Araldite DYO68 and zinc octylate were used to prepare resin compositions as shown in Table 3.

Stirring was carried out under reduced pressure at 90° C. for 20 minutes.

Then, these resin compositions were cured at 130°C for 24 hours, and an enameled wire with a wire diameter of about 0.15mm was coated with a
0 turns inner diameter 12mm, outer diameter 50mm, height 50mm
Ten epoxy-molded magnet coils each having a 6 mm thick winding embedded therein and a cured resin plate with a thickness of 6 mm were obtained.

After repeating 10 cycles of heat shock, in which an epoxy molded magnetic coil was heated at 130°C for 2 hours and then left in ice water at 0°C for 30 minutes, the crack occurrence rate was observed, and then an AC 6 0
A voltage withstand test was conducted at Hz and 5 kV for 1 minute, and the crack resistance and voltage resistance were examined based on the failure rate among 10 test products.

The impregnability was evaluated by cutting the coil to a thickness of 5 mm and observing the presence or absence of cavities and enameled wires falling out.

The hardness was measured at 100° C. using a 6 mm cured resin plate using a Barcol hardness meter.

In addition, for transparency, a 6 mm cured resin plate was placed in close contact with a Mincho typeface sample paper with type sizes classified into 20 types from 62nd grade (42 points - first issue) to 7th grade (5 points - 8th grade).
It was determined by a type series that can be read under direct sunlight.

The above test results are shown in Table 4.

As is clear from the above examples, the translucent epoxy resin composition of the present invention has excellent transparency and impregnation properties, as well as excellent hardness and crack resistance. Products molded using this process not only have improved durability, but are also extremely useful, as it is easy to see with the naked eye whether or not there is an abnormality in the parts embedded inside the product.

Claims (1)

[Claims] 1 (A) Bisphene, Nol A-based epoxy resin with an epoxy equivalent of 300 to 1000, (B) an epoxy equivalent of 100 to 3
00 cycloaliphatic epoxy resin, (q polybasic carboxylic acid anhydride as a curing agent and (D) glass fiber as a filler with a diameter:length ratio in the range of 1:2 to 500, A translucent epoxy resin composition characterized in that the ratio of (D) to the total amount of (A), (B), (C) and (D) is 10 to 50% by weight. 2. A translucent epoxy resin composition according to claim 1, characterized in that glass fibers whose surfaces have been treated with a silane-based or chromium-based coupling agent are used. 3. A tertiary amine as a curing accelerator; 3. The translucent epoxy resin composition according to claim 1 or 2, which contains a metal complex salt of an amine or a metal salt of an organic acid.