JPH04178421A - Epoxy resin composition - Google Patents

Abstract

PURPOSE:To obtain the subject composition, useful as resin molds, jigs, tools, etc., capable of providing simple curing operation and excellent in thermal conductivity, heat resistance, etc., without mold breaking by blending a polyfunctional amino-epoxy resin with a curing agent, a curing accelerator and metallic powder in specific amounts. CONSTITUTION:The objective composition is obtained by blending (A) a polyfunctional amino-epoxy resin having <=3000cP viscosity (25 deg.C) and an aromatic ring with (B) a curing agent such as an alicyclic amine, (C) a curing accelerator such as trisdimethylaminomethylphenol and (D) metallic powder [containing 15-50 wt.% particles with <=10mum particle diameter and <=6.5m<2>/g specific surface area and 30wt.% particles with <=1mum particle diameter], having <=200mum particle diameter and capable of exhibiting a particle size distribution of >=10 uniformity coefficient and <=10 curvature coefficient determined in a particle diameter cumulative curve at (15:85)-(40:60) ratio [components (A):(D)].

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to an epoxy resin composition containing metal powder, and more specifically, it can be highly filled with metal powder, has a simple curing method, and can be cured and molded. The present invention relates to an epoxy resin composition that has high thermal conductivity (and low internal strain).The epoxy resin composition of the present invention is particularly suitable for resin molds, other jigs, and various molded products.

[Prior Art] Epoxy resin compositions made by blending metal powder such as aluminum powder with Evo-xy resin are known as raw materials for resin molds.

However, in the past, most epoxy resin compositions for resin molds had a metal powder content of about 60% by weight or less, which caused mold cracking and damage, and problems in workability.

For example, Japanese Patent Publication No. 50-38606 discloses that a resin material in which 40 to 60 parts by weight of aluminum powder is added to 100 parts by weight of epoxy resin is molded into a resin mold. If the content of metal powder is low, the curing shrinkage rate of the resin mold is high (and the original model cannot be faithfully transferred.In addition, the thermal conductivity is low, so the resin mold is likely to be distorted, and In order to prevent
The curing process had to be carried out while gradually raising the temperature, resulting in problems such as poor curing operability.

Therefore, in order to improve the curing shrinkage rate and thermal conductivity, epoxy resin compositions containing a large amount of metal powder have been proposed.

For example, Japanese Patent Laid-Open No. 137623/1983 discloses creating a resin mold using a composition in which aluminum powder is blended in an amount equal to or more than epoxy resin. However, since a high viscosity bisphenol A epoxy resin is used, only metal powder with a large average particle size can be filled. As a result, the resulting resin mold not only has a poor casting surface finish, but also tends to have voids and distortions due to the settling of metal powder.゛Unexamined Japanese Patent Publication No. 2-53850 discloses that a cycloaliphatic epoxy resin with a viscosity of 5,000 centivoise (cps) or less has a particle size of 44 μm.
An epoxy resin composition has been proposed in which an equal or more amount of metal powder, preferably 60 to 75% by weight of the entire composition, is blended with a metal powder containing 50% by weight or more of fine powder having a particle size of 50% by weight or less. However, since it uses an alicyclic epoxy resin, it does not have sufficient heat resistance, and because it uses an acid anhydride curing agent, it cannot be cured at room temperature.

On the other hand, JP-A-63-178120 discloses that a polyglycidyl ether of aminophenol (a polyfunctional aminoepoxy resin having an aromatic ring) having an aromatic ring substituted with one or more alkyl groups is used as a liquid epoxy encapsulant. Alumina, fused silica, crystalline silica, glass, aluminum hydroxide,
Inorganic fillers such as hydrated aluminum account for 15 to 70% of the total
Compositions containing % by volume have been proposed. This inorganic filler has an average particle size of 1 to 1100 u, and is preferably spherical with an aspect ratio of 1 to 1.5. However, there is no disclosure regarding high filling of metal powder such as aluminum powder. According to the research results of the present inventors, instead of using an inorganic filler, the average particle size of
If only 100 μm spherical metal powder is blended, a highly fluid and highly filled material cannot be obtained, and a high-performance resin mold cannot be obtained.

[Problem to be solved by the invention]

The object of the present invention is to provide an epoxy resin composition containing metal powder, which can provide a highly filled material with good fluidity, can be cast in large quantities, can be easily cured, and can produce cured molded products. The object of the present invention is to provide a novel epoxy resin composition that has excellent thermal conductivity, heat resistance, etc., and provides a resin mold that does not crack.

As a result of intensive research to overcome the problems of the prior art, the present inventors found that an epoxy resin with a viscosity of 30.
A polyfunctional aminoepoxy resin having an aromatic ring of oO centiboise (25°C) or less is used, and the particle size is 20% as a metal powder.
It has been discovered that the above object can be achieved by highly filling metal powder having a particle size distribution of 0 μm or less and a specific particle size distribution, and based on this knowledge, the present invention has been completed.

[Means for Solving the Problems] Thus, according to the present invention, (A) a polyfunctional aminoepoxy resin having an aromatic ring having a viscosity of 3000 centivoise (25°C) or less, CB) a curing agent, and (C) a curing accelerator. , and (D) the particle size is 200 μm or less, the uniformity coefficient determined by the particle size cumulative curve is 10 or more, and the curvature coefficient is 10
Contains metal powder with the following particle size distribution, and the weight ratio of metal powder to epoxy resin (epoxy resin: metal powder) is 1.
An epoxy resin composition characterized in that the ratio is 585-40:60 is provided.

Further, according to the present invention, various molded products such as resin molds cured using the epoxy resin composition are provided.

The present invention will be explained in detail below.

(Polyfunctional aminoepoxy resin having an aromatic ring) The polyfunctional aminoepoxy resin having an aromatic ring used in the present invention is a polyglycidylated product of aminophenols.

As amine phenols, p-aminophenol,
Amine phenols such as m-amine phenol and 0-aminophenol, 4-amino-m-cresol, 4-amino-0-cresol, 6-amino-m-cresol,
Examples include amine phenols in which an aromatic ring is substituted with one or more alkyl groups, such as 5-amino-m, cresol, 3-ethyl-4-aminophenol, and 2-ethyl-4-aminephenol.

These polyglycidylated aminophenols themselves are well-known epoxy resins.

Among polyfunctional aminoepoxy resins having an aromatic ring, triglycidylated aminophenols represented by the following formula [I] are preferred.

G (In the formula, G represents a glycidyl group and R represents a hydrogen atom or a methyl group.) Conventionally, polyfunctional aminoepoxy resins having an aromatic ring, such as triglycidylated p-aminophenol,
Strong reactivity (high curing distortion, shrinkage, and heat generation; generally,
It has been used for glass fiber reinforced resin (FRP), etc. In the present invention, by blending a large amount of metal powder having a specific particle size distribution into this epoxy resin, the above-mentioned drawbacks of this resin are overcome, and an epoxy resin composition particularly suitable for resin molds is provided. do.

The polyfunctional aminoepoxy resin having an aromatic ring used in the present invention has a viscosity of 30QOcps or less when measured at 25°C,
Preferably it is 2500 cps or less. Viscosity is 3
If it exceeds 000 cps, it becomes difficult to blend a large amount of metal powder including fine powder.

It should be noted that other epoxy resins may be mixed as a minor component within a range that does not impair the purpose of the present invention.

(Curing agent) Examples of the curing agent used in the present invention include alicyclic amines, aliphatic amines, aromatic amines, polyamines such as dicyandiamide, dimer acid-modified (polyamide),
Modified polyamines such as ketone modification (ketimine), epoxide modification (epoxy adduct), thiourea addition modification, Michael addition modification, Michael addition modification; alicyclic acid anhydride,
Acid anhydrides such as aliphatic acid anhydrides, aromatic acid anhydrides, and halogenated acid anhydrides; polyphenols such as novolac type phenolic resins; polymercaptans; isocyanates; boron trifluoride complexes; imidazoles, etc. I can do it.

Among these curing agents, for example, if aliphatic amines, dimer acid-modified polyamines, polymercaptans, etc. are used, room temperature curing is possible.

The blending ratio of the curing agent is usually 0.6 to 1.3 equivalents, preferably 0.7 to 1 equivalent to the epoxy group of the epoxy resin.
．． It is 2 equivalents. If it is outside this range, the heat resistance of the cured molded product will be insufficient.

(Curing Accelerator) Examples of the curing accelerator used in the present invention include 2-ethyl-4-methylimidazole, 1-cyanoethyl-4-
Imidazole and its derivatives such as methylimidazole; trisdimethylaminomethylphenol, 2,4.
Tertiary amines such as 6-tris(dimethylamino)phenol; dimethylcyclohexylamine, boron trifluoride monoethylamine, and the like.

By using a curing accelerator, low temperature curing and shortening of curing time are possible.

The proportion of the curing accelerator used is usually 0.3 to 6 parts by weight per 100 parts by weight of the epoxy resin.

(Metal Powder) Examples of the metal powder used in the present invention include various metal powders such as aluminum powder, copper powder, and iron powder. Among them, aluminum powder has good thermal conductivity, The coefficient of thermal expansion is close to that of epoxy resin (,
It is preferable because it has good wettability with the epoxy resin, has a good finish on the casting surface, and has a low specific gravity so that the weight of the cured product can be reduced. Further, among aluminum powders, atomized powder is particularly preferable because it has a small specific surface area and is physically well entangled with the epoxy resin.

The metal powder used in the present invention has a particle size of 200 μm or less and a uniformity coefficient of 10 or more determined by a particle size shipping curve,
The metal powder has a good particle size distribution with a curvature coefficient of 10 or less.

The particle size shipping curve is based on JIS A-1204 (particle size test)
Created according to. That is, the particle size was 20 when the particle size distribution was measured using Microtrac 7995 manufactured by Nikkiso Co., Ltd.
For metal powders of 0 μm or less, measure the "passing weight percentage" for each particle size, and take the result by plotting the particle size on the logarithmic scale of the semi-ply paper and the passing weight percentage for the entire sample on the arithmetic scale. Plotted.

From the obtained particle size shipping curve, 60% particle size (D,.

μm)′, 30% particle size (D s o 11 m ), and 10% particle size (D, μm) were read, and the uniformity coefficient (Ue) and curvature coefficient (tJ,′) were calculated using the following formula. .

Uc=D6°/D,.

Uc ′” (Di.) ” / (D +oX
Dgo) The larger the uniformity coefficient is, the wider the particle size distribution is, and the curvature coefficient quantitatively indicates that the particle size distribution is step-like. In the particle size shipping curve, a metal powder exhibiting a particle size distribution with a uniformity coefficient of 10 or more and a curvature coefficient of 10 or less has a smooth particle size shipping curve, indicating a good particle size distribution.

The curvature coefficient is preferably 5 or less, more preferably 1 to 2.
It is.

If the uniformity coefficient is less than 10 or the curvature coefficient is outside the above range, it is difficult to obtain a highly fluidized material,
It is not possible to obtain a cured molded product that is free from distortion and has excellent thermal conductivity.

The upper limit of the particle size of metal powder is 200 μm, and 200 μm
If a metal powder containing metal powder with a particle size exceeding 100 mm is used, the uniform dispersibility will be poor, and metal powder with a large particle size will settle, or the finish of the casting surface will be poor.

In addition, the proportion of particles with a particle size of 10 μm or less in the metal powder is 15 to 50.
% by weight, more preferably 20-50% by weight, particle size 1μ
It is desirable that the proportion of m or less is 30% by weight or less, more preferably 15% by weight or less. If the proportion of fine powder is too large, the viscosity of the composition may increase, making blending difficult. By having the composition of the metal powder within the above range,
A highly filled epoxy resin composition with good uniform dispersibility can be obtained.

Furthermore, it is preferable that the specific surface area (BET method, nitrogen adsorption method) of the metal powder with a particle size of 10 um or less is 6.5 d/g or less. The reason is that when the specific surface area exceeds the above range, the amount of epoxy resin required to wet the surface of the metal powder increases, making it difficult to achieve high filling.

The weight ratio of metal powder to epoxy resin (epoxy resin: metal powder) needs to be 15:85 to 40:60, preferably 20:80 to 40:
It is 60.

By having such a large blending ratio of metal powder having a specific particle size distribution, the following effects can be achieved.

(1) The curing shrinkage rate is reduced, and when a resin mold is used, the original model can be faithfully transferred, so the precision of the mold is improved.

(2) The thermal conductivity of the cured product is high (as well as the linear expansion coefficient is small), so distortion is less likely to occur and the shape is better.When molded into a resin mold, the surface and interior are heated uniformly. This prevents mold cracking.Especially when using resin molds that are used under high temperatures such as injection molding, the hot strength increases, preventing mold cracking and breakage.Also, it has good heat dissipation. Therefore, the temperature of the resin mold drops quickly, making it possible to cast large quantities.

(3) Since the epoxy resin composition itself has good thermal conductivity, the temperature distribution during curing becomes uniform, resulting in a cured product with little distortion, and there is no need to heat in stages during curing. Curing operation becomes easy.

By the way, some of the metal powder with a particle size of 10 μm or less in the metal powder can be replaced with an inorganic compound with a particle size of 10 μm or less. This makes it possible to reduce costs while maintaining excellent physical properties. can.

Inorganic compounds include aluminum hydroxide, alumina,
Examples include powders such as silica and glass. However, when part of the metal powder is replaced with these inorganic compounds, it is necessary that the entire particle size distribution satisfies the specified conditions of the uniformity coefficient and curvature coefficient.

(Epoxy resin composition) The viscosity (25°C) of the epoxy resin composition of the present invention is usually 500,000 cps or less, preferably 250,000 cps or less, and even though a large amount of metal powder is blended, It has good fluidity and is suitable as a casting resin composition for direct inversion molding from a master model.

The epoxy resin composition of the present invention can be cast and cured at low temperatures by selecting a curing agent. Therefore, when creating a resin mold, a wide range of materials can be selected for the original model, and vacuum degassing casting at room temperature is also easy.

The epoxy resin composition of the present invention can be cured by heating, but in that case, stepwise heating operations are not required.
For example, since it can be cured by heating from 50° C. to 150° C. at once, the curing operation is simplified. Furthermore, large quantities can be cast, and molded products with a thickness of 10 cm or more can be created by casting.

The molded product obtained by curing the epoxy resin composition of the present invention has high thermal conductivity, and conventional products have a thermal conductivity of 2.
, OX 10-” cal/cm-sec, 'C
2,5 X 10-” ca
l/cmSec.

Indicates temperature above ℃. In addition, the cured molded product has high heat resistance,
The deflection temperature under load (HDT) is 200°C or higher, and the glass transition temperature (Tg) is 170°C or higher. The coefficient of linear expansion is 3
．． 5X10-' or less, the curing shrinkage rate is -0.05 to +0.
The range is 0.05%.

[Example] The present invention will be described in more detail below with reference to Examples and Comparative Examples.

[Example 1] 100 parts by weight of triglycidylated 4-amino-o(m)-cresol (a polyfunctional aminoepoxy resin with a viscosity of 1200 centivoids at 25°C) and a filler shown in Table 1 (I). ) liquid and bis(3-methyl-
An epoxy resin composition was obtained by mixing liquid (II) consisting of 6 parts by weight of 4-aminocyclohexyl)methane (curing agent) and 0.8 parts by weight of 2-ethyl-4-methylimidazole (curing accelerator). The viscosity (c p s ) of the composition at 25° C. was measured and shown in Table 1.

This epoxy resin composition was cast into a silicone resin mold at room temperature, and after vacuum defoaming, it was cured at 50° C. for 6 hours and demolded. Next, the temperature was raised to 150° C. at a temperature increase rate of 5° C. per minute and cured for 5 hours.

The physical properties of the obtained cured product are shown in Table 1. Further, the particle size distribution of the filler used is shown in Table 2.

Notes ($1) to (umbrella 9) in Table 1 are as follows.

(*l) AI powder with a specific surface area (BET method, nitrogen adsorption method) of particles with a particle size of 10 μm or less of 1.6 resistance/g.

(*2) Al (OH) powder with a particle size of 10 μm or less, an average particle size of 1.5 μm, and a specific surface area (BET method, nitrogen adsorption method) of 5.6 g/g.

(Umbrella 3) According to JIS A-1204 (particle size test),
Particle size distribution was measured using Microtrack 7995 manufactured by Nikkiso Co., Ltd. Table 2 shows the passing weight percentage for each particle size of each particle size distribution.

(Umbrella 4) Viscosity (cps) The viscosity at 25°C was measured using a B-type viscometer.

(Umbrella 5) Curing shrinkage rate (%) Curing shrinkage rate was calculated by reading with a microscope 100 mm between inverted plane marking lines at 25°C.

(*6) Coefficient of linear expansion Thermomechanical analyzer TMA manufactured by Seiko Electronics Industries, Ltd.
It was measured by TMA (Thermomechanical Analysis) method using 120.

(7th grade) Thermal conductivity (cal/cm-sec, ・℃)
Measured using the Tsukiyama method (acetone/benzene method).

(N8) Load deflection temperature (''C) Measured according to JIS K-6911.

(Medium 9) Glass transition temperature (''C) Thermomechanical analyzer TMA12 manufactured by Seiko Electronics Co., Ltd.
It was measured by TMA (Thermomechanical Analysis) method using 0.

(Margin below) Table 2 [Example 2] Each epoxy resin composition of Experiment No. 1.2 of Example 1 was cast into a mold and left at room temperature for 12 hours. Another 60℃
The mold was left for 5 hours and then demolded.

The formwork is a silicone resin mold with a length of 230m.
It has a rectangular opening measuring 330 mm x 330 mm, and has a depth of 65 mm.
mm, in the center of the bottom, 200 mm long x 300 mm wide
A convex portion with a height of 50 mm is provided.

Next, the temperature was increased to 150°C at a rate of 5°C per minute, and the temperature was increased to 150°C.
After curing for a while, it was immersed in water at 20°C and subjected to temperature shock (
sudden temperature changes). After sufficiently cooling, the appearance was observed, and no cracks were found in any of them.

〔Effect of the invention〕

According to the present invention, a highly filled epoxy resin composition containing metal powder and having good fluidity can be obtained. The epoxy resin composition of the present invention can be cast in large quantities, is easy to cure, has excellent thermal conductivity, heat resistance, etc., and is suitable for resin molds that do not crack.

Claims (7)

[Claims] (1) (A) a polyfunctional aminoepoxy resin having an aromatic ring with a viscosity of 3000 centipoise (25°C) or less, (B) a curing agent, (C) a curing accelerator, and (D) a particle size of 200 μm or less, And, the uniformity coefficient determined by the particle size accumulation curve is 10 or more, and the curvature coefficient is 10.
Contains metal powder with the following particle size distribution, and the weight ratio of metal powder to epoxy resin (epoxy resin: metal powder) is 1.
An epoxy resin composition characterized in that the ratio is 5:85 to 40:60. (2) The proportion of particles with a particle size of 10 μm or less in the metal powder is 15 to 50
The epoxy resin composition according to claim 1, wherein the proportion of particles having a particle size of 1 μm or less is 30% by weight or less. (3) The epoxy resin composition according to claim 1 or 2, wherein the metal powder with a particle size of 10 μm or less has a specific surface area (BET method, nitrogen adsorption method) of 6.5 m^2/g or less. (4) The epoxy resin composition according to claim 1, wherein at least a part of the metal powder with a particle size of 10 μm or less in the metal powder is replaced with an inorganic compound with a particle size of 10 μm or less. (5) An epoxy resin molded article obtained by curing the epoxy resin composition according to any one of claims 1 to 4. (6) Thermal conductivity is 2.5 x 10^-^3 cal/cm・
sec. 6. The epoxy resin molded article according to claim 5, which has a temperature of at least .degree. (7) The epoxy resin molded article according to claim 5 or 6, which is a resin mold.