JP2634663B2 - Filler for resin and liquid epoxy resin composition - Google Patents

Description

The present invention relates to a filler for a resin and a liquid epoxy resin composition, and more particularly, to an electronic component having good moldability and excellent mechanical strength and thermal strength. The present invention relates to a liquid epoxy resin composition for sealing.

<Conventional Technology> Liquid epoxy resins are widely used as insulating materials for electric and electronic components because of their excellent electrical insulation and moisture resistance.

However, in the conventional liquid epoxy resin composition, the occurrence of cracks due to reaction shrinkage during heat curing becomes a problem, and at the same time, cracks occur in the cured product due to the difference in the coefficient of thermal expansion between the element to be cast and the substrate as the bonding surface. There was a problem that occurred.

In order to alleviate these problems, methods for adding a flexibility-imparting agent and alleviating curing conditions have been proposed to alleviate internal stress, but have not been satisfactory. Further, in order to reduce the coefficient of thermal expansion of the resin composition itself, high filling with an inorganic filler or the like has been attempted, but in this case, the resin composition itself has a high viscosity, resulting in molding failure. Thus, high packing using spherical silica surface-treated with alkoxysilane has also been attempted (Japanese Patent Application Laid-Open No. 61-296020), but this is also undesirable because the viscosity increases. Therefore, the appearance of a liquid epoxy resin composition that satisfies the mechanical strength and thermal shock resistance of a cured product without increasing the viscosity has been awaited.

<Problems to be Solved by the Invention> The present inventors have conducted various studies to solve the above problems, and as a result, by blending a specific amount of a spherical inorganic powder having a specific particle size configuration and a crushed inorganic powder, The present inventors have found that a liquid epoxy resin composition which is excellent in moldability and does not decrease in mechanical strength can be obtained, and completed the present invention.

<Means for Solving the Problems> That is, the present invention has the following gist.

1. The weight ratio of (a) / (b) of the spherical inorganic powder (a) and the crushed inorganic powder (b) having the following particle size composition is 9/1 to 5
A filler for resin, characterized in that it is contained at a ratio of / 5.

[Spherical inorganic powder (a)]

The average particle size is 12 to 20μ, the content of 2μ or less is 7 to 15% by weight, 12μ or less is 35 to 50% by weight, 24μ or less is 60 to 75% by weight, and 45μ or more is 6% by weight or less.

[Crushed inorganic powder (b)]

The average particle size is 8 to 25μ, the content of 2μ or less is 5 to 15% by weight, 12μ or less is 30 to 60% by weight, and 24μ or less is 50 to 85% by weight.

2. The resin filler according to claim 1, wherein the material of the inorganic powder is crystalline silica, fused silica, alumina, calcium carbonate, silicon nitride, silicon carbide, aluminum nitride or boron nitride.

3. A liquid epoxy resin composition comprising the resin filler according to claim 1 or 2 in an amount of 60 to 80% by volume.

 Hereinafter, the present invention will be described in more detail.

Examples of the material of the spherical inorganic powder (a) or the crushed inorganic powder (b) of the present invention include crystalline silica, fused silica, alumina, calcium carbonate, silicon nitride, silicon carbide, aluminum nitride, boron nitride and the like. It is not limited to.

The average value of the spherical inorganic powder (a) referred to in the present invention and the needleiness (length / short length ratio) produced by a thermal spraying method, a synthesis method, or the like is as follows.
1.3 means the following. Its average particle size is 12-20μ. When the content of particles having a particle size of 2μ or less is 7% by weight, the content of particles having a particle size of 12μ or less is 35% by weight, and the content of particles having a particle size of 24μ or less is less than 60% by weight, the viscosity of the resin composition itself is low. Crack generation rate increases. On the other hand, the content of 2μ or less particles is 15% by weight, the content of 12μ or less particles is 50% by weight, the content of 24μ or less particles is 75% by weight, and the content of 45μ or more particles is 6% by weight. If it exceeds this, the crack generation rate decreases, but the viscosity of the resin composition itself increases. Preferably, the average particle size is 14 to 17μ, the content of particles of 2μ or less
10 to 12% by weight, the content of particles having a size of 12μ or less is 40 to 44% by weight, the content of particles having a size of 24μ or less is 63 to 67% by weight, and the content of particles having a size of 45μ or more is 5% by weight or less. The maximum particle size is 74 μ.

The crushed inorganic powder (b) referred to in the present invention may be any powder as long as it is crushed by a crusher or the like. Its average particle size is between 8 and 25μ. When the content of particles of 2 μ or less is 5
When the content of the particles having a particle size of 12 μm or less is less than 30% by weight and the content of the particles having a particle size of 24 μm or less is less than 50% by weight, the viscosity of the resin composition itself is low but the crack generation rate is high. on the other hand,
When the content of particles having a particle size of 2μ or less is 15% by weight, the content of particles having a particle size of 12μ or less is 60% by weight, and the content of particles having a particle size of 24μ or less exceeds 85% by weight, the crack generation rate is low. The viscosity increases. Preferably, the average particle size is 12-17μ
The content of particles of 2 μ or less is 8 to 11% by weight, the content of particles of 12 μ or less is 40 to 50% by weight, and the content of particles of 24 μ or less is 65 to 75% by weight. The maximum particle size is 150 μ.

Next, the cyclic inorganic powder (a) and the crushed inorganic powder (b)
Will be described. The mixing ratio of both is (a)
The weight ratio of / (b) is 9/1 to 5/5. When the ratio exceeds 9/1, the crack generation rate increases, and when the ratio is less than 5/5, the viscosity of the resin composition itself increases.

Examples of the resin in which the filler of the present invention is used include a urea resin, a melamine resin, a phenol resin, an epoxy resin, an unsaturated polyester, an alkyd resin, and a polyphenylene sulfide, and a liquid epoxy resin is preferable. In the present invention, the amount of the filler is set to 60 to 80% by volume based on the total epoxy resin composition. When the amount is less than 60% by volume, the crack generation rate becomes high. This is because the viscosity of the composition itself is high and moldability is deteriorated.

The liquid epoxy resin used in the present invention may be any one which is generally known as a liquid epoxy resin, for example, bisphenol type epoxy resin, alicyclic type epoxy resin, novolak type epoxy resin, complex type Examples thereof include a cyclic epoxy resin and a glycidyl ester epoxy resin, which may be substituted with bromine or the like for flame retardancy. In the present invention, at least one selected from the above groups is used. Among these, a novolak-type epoxy resin having good electrical characteristics and moisture resistance at high temperatures is preferable.

Epoxy The resin curing agent may be any as long as it is generally known, for example, polycarboxylic acid anhydrides, amines, phenolic resins, polyamides, dicyandiamide, EF ₃ - amine complex, imidazole and the like can give.

Examples of polycarboxylic anhydrides include liquid dibasic anhydrides such as methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, and methylendomethyltetrahydrophthalic anhydride, as well as phthalic anhydride, hexahydrophthalic anhydride, and tetrahydrophthalic anhydride. Acids, trimellitic anhydride, pyromellitic anhydride, benzophenonetetracarboxylic anhydride, polyazelain anhydride, and the like. Examples of the amine include triethylenetetramine, isophoronediamine, metaphenylenediamine, diaminodiphenylmethane, and tris-dimethylaminoethylphenol. Examples of imidazole include 2-methyl-4-ethylimidazole, 1-benzyl-2-methylimidazole, 2-methylimidazole, and imidazole salts.

The curing accelerator used in the present invention may be any one as long as it is generally used as a curing accelerator for epoxy resins, for example, various amines such as benzyldimethylamine and trisdimethylaminomethylphenol, and triamines. Various phosphines such as phenylphosphine, tricyclohexylphosphine, tributylphosphine, and methyldiphenylphosphine; and imidazoles such as 2-methylimidazole, 2-ethyl-4-methylimidazole, and 1-cyanoethyl-2-ethyl-4-methylimidazole. And at least one selected from the group consisting of these is used.

In addition to the above, if necessary, a silane coupling agent,
Coupling agents such as titanate coupling agents, flame retardants such as antimony trioxide, pigments such as carbon black,
A release agent such as waxes and a flexibility-imparting agent such as silicone oil may be blended.

<Examples> Next, the present invention will be described more specifically with reference to examples.

Examples 1 to 13 Comparative Examples 1 to 8 By passing through a high-temperature flame, spherical silica powders shown in Table 1 were obtained. Further, a crushed silica powder shown in Table 1 was obtained using a vibration mill. The fillers shown in Table 1 are blended in the proportions shown in Table 3, and the proportions shown in Table 2 are used together with a liquid epoxy resin, a curing agent, and a curing accelerator under vacuum using a universal mixer, kneader, or the like. To obtain a liquid epoxy resin composition.

Each of these resin compositions was cured at 150 ° C. for 5 hours to prepare test pieces. Table 3 shows the measurement results of the viscosity, bending strength and crack generation rate.

(Measurement Method) (1) Viscosity: Measured at a temperature of 45 ° C. using an E-type viscometer (manufactured by Tokyo Keiki Co., Ltd.) using a 3 mm cone.

(2) Flexural strength: measured by a method according to JIS-K-6911.

(3) Crack generation rate: 100 specimens at -150 to 260 ° C
The crack generation rate was determined by multiplying the number of times by 10 in the cooling / heating cycle (number of broken pieces / 100) × 100.

(4) Particle size distribution and average particle size: Measured using a particle size distribution measuring device (Model 715, manufactured by Cirrus Co.). The particle size when the cumulative weight% of the particle size distribution was 50% was defined as the average particle size.

(5) Particle size of 45 μ or more: Measured by a wet JIS sieve method.

(6) Needleness: Measured with an image processing device SPICA (manufactured by Nippon Avionics).

<Effects of the Invention> According to the present invention, a liquid epoxy resin composition having excellent moldability and strength properties can be obtained.

Claims (3)

(57) [Claims] 1. A composition comprising a spherical inorganic powder (a) and a crushed inorganic powder (b) having the following particle size composition in a weight ratio of (a) / (b) of 9/1 to 5/5. A filler for a resin, comprising: [Spherical inorganic powder (a)] The average particle diameter is 12 to 20 μm, the content of 2 μm or less is 7 to 15% by weight, 12 μm or less is 35 to 50% by weight, 24 μm or less is 60 to 75% by weight, and 45 μm or more is 6%. % By weight or less. [Crushed inorganic powder (b)] The average particle size is 8 to 25 µm, the content of 2 µ or less is 5 to 15 wt%, 12 µ or less is 30 to 60 wt%, and 24 µ or less is 50 to 85 wt%. 2. The resin filler according to claim 1, wherein the material of the inorganic powder is crystalline silica, fused silica, alumina, calcium carbonate, silicon nitride, silicon carbide, aluminum nitride or boron nitride. 3. The resin filler according to claim 1 or 2, wherein
A liquid epoxy resin composition comprising 80% by volume.