JPH0710925B2 - Conductive resin molding - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive resin molded body, and more particularly to a conductive resin molded body suitable for forming a mold.

In this specification, the terms "%" and "parts" mean "wt%" and "parts by weight", respectively.

[0003]

2. Description of the Related Art Recently, there has been an increasing demand for product differentiation and individualization. For example, even for the same product, a plurality of "sister products" having different color tones are manufactured and sold separately. Many accessories are also being manufactured. In addition, the product life cycle is becoming shorter in order to quickly respond to consumer needs. Under such circumstances, there is an accelerating tendency toward a small quantity and a large variety of parts used in products, such as plastic molded parts. In addition, trial production for new product development and model change of existing products has become more frequent. Therefore, in order to speed up the commercialization of plastic molded parts, simple molding dies have become popular.

One of the most popular simple molding dies at present is a resin mold. In the manufacture of this resin mold, a liquid resin composite material prepared by mixing a powder of a metal or alloy such as iron, copper, or aluminum with an epoxy resin of a room temperature curing type which is usually a two-liquid mixture was fixed as a raw material in a frame. Pour into the master model, that is, the model of the shape you want to create. On this occasion,
In order to remove the air trapped inside, vacuum deaeration is performed, followed by curing, and the master model is removed, and a mold is produced by transfer. Grinding is usually not performed in the production of resin molds. This is because the room temperature curing type epoxy resin prepared by mixing the two liquids has low heat resistance, rigidity and strength, and thus the resin mold may be thermally deformed and damaged by mechanical processing.

Further, the resin mold produced by transfer is also lacking in heat resistance and durability because the epoxy resin itself used has low heat resistance. Therefore, it can be used as a resin for molding at a relatively low temperature, for example, an injection molding mold made of ABS, polyethylene, vinyl chloride, etc., but the number of molding times is limited.

Japanese Unexamined Patent Publication No. 1-278567 proposes a combination of a resin having excellent heat resistance and a metal powder, that is, a thermosetting epoxy resin and an aluminum powder. A mold is manufactured from this material by a heat compression molding method. That is, a mold material is poured into a master model fixed in a frame and heated and pressed to manufacture a molding die. At this time, when a resin that generates gas is used, the pressure is lowered during the molding to perform “gas release”, so that no void is generated inside the resin mold.

Generally, when a resin mold is manufactured by transfer from a master model, it is not possible to directly manufacture a mold of an arbitrary shape. If the master model has an undercut or the shape is complicated, after transfer, As a post-process, it is necessary to grind the mold by machining. The resin mold described in the above-mentioned JP-A-1-278567 has a significantly improved rigidity, strength and the like by using a heat resistant resin and an aluminum alloy powder together, and facilitates grinding by machining. It is excellent in that it has become. However, post-processing by electric means such as electrical discharge machining, which is rapidly prevailing, is impossible because of its excellent workability, short machining time, and high machining accuracy. This is because the conductivity of the resin type as the material to be processed is low. That is, this resin mold contains aluminum which is originally a highly conductive metal, but since the aluminum used is a powder solidified by quenching, it has a ductile amorphous phase containing crystal water on the surface. Because it has an oxide film which is a stable insulator, it has low conductivity. In addition, since resin is generally lower in conductivity than metal, the above mold made of such a composite material of aluminum powder and resin does not exhibit excellent conductivity required for electric discharge machining.

In the case of a mold made of a composite material composed of a mixture of a room temperature curing type epoxy resin and a metal or alloy powder prepared by mixing the above two liquids, it is impossible to perform electric discharge machining for the same reason. .

[0009]

SUMMARY OF THE INVENTION Therefore, the main object of the present invention is to provide a resin mold having excellent conductivity which can be post-processed by electric discharge machining.

[0010]

Means for Solving the Problems As a result of intensive studies conducted by the present inventor in view of the above-mentioned state of the art, a resin molding containing aluminum alloy powder has material properties such as strength, rigidity, and lightness. It is advantageous in that, when a powder of a metal or an alloy thereof having a specific electric resistance value of 100 μΩcm or less is further added to such a resin molded body, a high electrical conductivity that enables electric discharge machining is obtained. It has been found that a product having the combination can be obtained. Further, they have found that such a resin molded product is not only useful as a molding die, but also useful as a structural component that is lightweight and requires conductivity.

That is, the present invention provides the following conductive resin moldings (hereinafter sometimes referred to as resin moldings): A conductive resin molded body comprising the following components A, B and C: A: Aluminum alloy powder 25 to 60%, B: At least one kind of powder of metal and its alloy having a specific electric resistance value of 100 μΩcm or less (however, aluminum 15-60%, C; synthetic resin 15-25%.

2. The electroconductive resin molding according to item 1, wherein the B component is copper powder.

3. Item 2. The conductive resin molded article according to Item 1, wherein the C component is a synthetic resin having a heat resistance of 200 ° C or higher.

4. 2. The conductive resin molded body according to item 1, wherein the molded body has a specific gravity of 4 or less.

The aluminum alloy powder used as the component A in the present invention hardly contributes to the conductivity as described above, but is itself lightweight and has excellent physical properties such as high strength and high rigidity. Therefore, the weight of the resin molded body is reduced and its physical properties are improved. As such an aluminum alloy,
Al-Si, Al-Si-Cu, Al-Si-Ni, A
1-Fe and the like are exemplified. The particle size of the aluminum alloy powder is usually 100 mesh (150 μm) or less,
More preferably, it is 250 mesh (63 μm) or less. If the particle size of the aluminum alloy powder is too large, the aluminum alloy powder does not disperse uniformly in the molded body, so the strength of the molded body decreases, and the aluminum alloy powder sticks out on the machined surface and becomes smooth. May not be obtained.

The metal component used as the B component in the present invention is at least one kind of powder of metal and its alloy (specifically, aluminum alloy powder is excluded) having a specific electric resistance value of 100 μΩcm or less. The component B not only improves the electrical conductivity and thermal conductivity of the resin molded product, but also exerts the effect of suppressing its thermal expansion. Specific electric resistance value is 100μ
If it exceeds Ωcm, it becomes difficult to impart sufficient conductivity to the resin molded product. Such metal components are not particularly limited, but metals such as copper, iron, nickel, and titanium, brass (Cu-Zn), and silver (Cu-Ni-Z).
n), manganin (Cu-Mn-Ni), alloys such as stainless steel, and the like. Of these, copper is
It is most preferable because it has excellent electrical conductivity and thermal conductivity. The particle size of the metal component powder is usually 100 mesh (15
0 μm) or less, and more preferably 250 mesh (63 to μm) or less. If the particle size of the copper powder is too large, the same problem as in the case of the above aluminum alloy occurs.

The synthetic resin used as the C component in the present invention has a temperature of 200 ° C. or higher so that the molding die exhibits sufficient strength, rigidity and hardness even during injection molding and compression molding carried out at around 200 ° C. It is preferably durable. Examples of such a resin include thermoplastic resins such as polyether sulfone resin, polyetherimide resin and polyamideimide resin, and thermoplastic resins such as polyimide resin, thermosetting epoxy resin and phenol resin.

The resin molded product of the present invention comprises the component A of 25 to 60.
%, B component 15 to 60% and C component 15 to 25%, and their specific gravity is 4 or less. Since the blending ratio of each component is related to each other and affects the physical properties of the resin molded product, it is not always appropriate to state the reasons for limiting each component individually. On the street.

If the amount of the component A is too small, the strength and rigidity of the resin molding will be insufficient, and the weight reduction property will not be achieved. If the amount of the component A is too large, the amount of the other component relatively decreases, so that the desired performance derived from the other component cannot be obtained.

If the amount of the B component is too small, the conductivity of the resin type becomes low, whereas if the amount of the B component is too large, the amounts of the other components relatively decrease, and thus, too. The desired performance derived from other components cannot be obtained. On the other hand, if the amount of the component B is too large, the specific gravity of the resin molded body becomes larger than 4 and it becomes difficult to handle a large-sized mold, and the lightness, which is one of the greatest advantages of the resin molded body, is impaired. Be done.

When the amount of the component C is too small, the amount of the resin becomes insufficient and voids are formed, so that a dense resin molded product cannot be obtained and the strength is deteriorated. On the other hand, when the amount of the C component is too large, the conductivity decreases, and other properties required for the mold such as good thermal conductivity and high strength also decrease. In particular, a decrease in thermal conductivity brings about a long molding cycle in injection molding and impairs productivity. If the molding cycle is shortened, a heat storage phenomenon occurs in the molding die, and the strength of the die is reduced due to the temperature rise, and the die is damaged.

The resin molded product according to the present invention can be obtained by molding a raw material comprising components A, B and C according to a conventional method. That is, the components A, B and C are uniformly mixed in a predetermined ratio by a blender or the like, and compression molded under heating as described above to obtain a molded body. Then
Machining including electric discharge machining is performed to obtain a predetermined mold.

[0023]

The resin molded product according to the present invention has good electrical conductivity to the extent that electric discharge machining can be performed, and has excellent heat resistance.
It has the characteristics of high thermal conductivity and low thermal expansion. Therefore, the mold material (various kinds of metal for plastic molding)
Mold, hot stamping mold for printing, etc.) , and can be used as various structural parts that are lightweight and require conductivity.

[0024]

EXAMPLES Examples will be shown below to further clarify the features of the present invention.

Example 1 A resin molded body was produced by using each raw material containing components A, B and C in the proportions (% by weight) shown in Table 1.

[0026]

[Table 1]

Details of the components A, B and C are as follows.

A-component aluminum alloy powder: Atomized powder of Al-12Si-4.5Cu, particle size 250 mesh (63 μm) or less.

Aluminum powder: Atomized powder having a purity of 99.3% or more and a particle size of 250 mesh (63 μm) or less.

Component B copper powder: a powder having a purity of 99.5% or more, a particle size of 250 mesh (63 μm) or less, and a specific electric resistance value of 1.7 μΩcm.

SUS316L powder: atomized powder, particle size 25
0 mesh (63 μm) or less, specific electric resistance value = 80 μΩ
cm.

Western silver type 4 powder ... Atomized powder, particle size 25
0 mesh (63 μm) or less.

Iron powder: Atomized powder having a purity of 99.0% or more, a particle size of 250 mesh (63 μm) or less, and a specific electric resistance value of 9.8 μΩcm.

Component C thermosetting epoxy resin: trademark “Bestlex LS”,
Sumitomo Chemical Co., Ltd. Polyethersulfone resin ... Trademark "VICTREX",
Sumitomo Chemical Co., Ltd. two-component mixed epoxy resin Epoxy resin: Trademark "T-301 / R-4", Nippon Ciba Geigy Co., Ltd. curing agent: Trademark "T-301 / H-4" Heat as C component When a curable epoxy resin is used, a raw material mixture containing components A, B and C is uniformly mixed with a V blender, and a predetermined amount is filled in a metal frame, and then a pressure of 50 kg / cm ² and a temperature of 200 are used. The temperature was raised to 0 ° C., compression molding was performed, and then curing was performed at 200 ° C. for 3 hours to obtain a resin molded body.

When a polyether sulfone resin was used as the C component, a resin molding was obtained in the same manner as when a thermosetting epoxy resin was used.

When a two-component mixed epoxy resin is used as the component C, the epoxy resin containing aluminum powder and the curing agent are uniformly mixed and then poured into a frame,
The resin was degassed in vacuum, pre-cured at 50 ° C. for 8 hours, and then cured at 180 ° C. for 20 hours to obtain a resin molded body.

Table 2 shows the resin moldings obtained as described above.
It was subjected to various characteristic tests shown in.

[0038]

[Table 2]

From the results shown in Table 2, the strength and dimensional stability required for the molding die can be improved by adding powder of a metal or its alloy having a certain conductivity or more as the B component.
A resin-formed body capable of electric discharge machining was obtained without impairing properties such as thermal conductivity. In particular, when copper powder is used as the B component, conductivity, dimensional stability, thermal conductivity,
In terms of electrical discharge machinability, etc., overall excellent results have been obtained.

Claims (4)

[Claims] 1. A conductive resin molding comprising the following components A, B and C: A; aluminum alloy powder 25 to 60%, B; at least one of metal and its alloy powder having a specific electric resistance value of 100 μΩcm or less. Seed (excluding aluminum alloy powder) 15 to 60%, C; Synthetic resin 15 to 25%. 2. The conductive resin molding according to claim 1, wherein the component B is copper powder. 3. The conductive resin molding according to claim 1, wherein the C component is a synthetic resin having a heat resistance of 200 ° C. or higher. 4. The conductive resin molded body according to claim 1, wherein the specific gravity of the molded body is 4 or less.