JPS58166028A - Composite conductive type molded article - Google Patents

Abstract

PURPOSE:To keep strength suitable to an product and prevent the product from generating warpage by a method wherein a conductive molded piece with a large projected area and a small thickness is divided into a molded portion requiring conductive function and a base supporting said molded portion. CONSTITUTION:A hole having a suitable shape and size (l1>=l2, l1/d<=75) is bored on a base plate 1 having a large projected area, a small thickness and a dimension ratio l>d>75 and a conductive molded piece having a suitable shape and size is provided on this hole portion. An insulating or conductive broad of thermosetting resin, thermoplastic resin, rubber or metal is used for the base 1 while powdery or fibrous material such as graphite, carbon black, etc. as conductive filler is used for conductive filler dispersion molding material, while thermosetting resin, thermo-plastic resin or rubber are used for resin component.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a composite conductive molded product having an excellent conductive function and a thin wall thickness compared to its projected area. It is conceivable that carbon black, graphite, or various conductive metal powders are made by dispersing them in a polymeric material to form the material.

However, this method cannot always be easily used depending on the performance required of the molded product, such as conductivity and strength, and the shape and dimensions of the molded product. For molded products with shapes and dimensions that have a large projected area, the flow characteristics of the molding material during molding become an important property, and even though electrical conductivity and strength properties are limited in relation to this property. It's not too much to say. That is, in a molding material in which a conductive filler is dispersed, a large amount of the conductive filler must be generally added in order to improve the conductivity, that is, to lower the resistance. In other words, resin and rubber components, which are polymeric materials that play a role in moldability and strength retention, must be reduced. As a result, the most important molding processability as a molding material is lost, and strength is also lost. However, according to the experience of the inventors, relatively small molded products can often be manufactured without any major problems, but the area is large and the wall thickness is small. In a plate-shaped molded product, that is, in a molded product in which the molding material has a long flow distance during molding and has a large flow resistance during flow, the above-mentioned drawbacks become a major problem.

In order to make it possible to form plate-shaped products as described above,
However, it is necessary to evenly distribute and install the molding material in a mold with a large plate surface within a short period of time, and then mold it with extremely high molding pressure using a large-capacity compression molding machine.
According to the experience of the present inventors, the plate-shaped molded product obtained in this way also has a low yield as a molded product, the lack of strength is virtually unresolved, and furthermore, the plate-shaped molded product suffers from warping peculiar to a plate-shaped molded product. This phenomenon occurs and the product does not meet the requirements.

As is well known and as mentioned above, this drawback arises when a large amount of conductive filler is added, and when the amount of conductive filler added is low, e.g., carbon black is added in a weighted amount of %. Resin-based materials do not pose problems in terms of molding and strength.

Therefore, one aspect of the present invention is to eliminate the above-mentioned drawbacks and to
The purpose of the present invention is to provide a conductive plate-shaped molded product that has excellent conductive performance and solves problems such as strength and warping.

Generally, in order to obtain high conductive performance, conductive fillers are added ranging from about ω weight % to 10 weight %. The results of experiments on the moldability of various thicknesses were conducted using burnt molding materials made of a circular plate with a diameter of 150 m, a square plate with a side length of 150 m, and a square plate with a side length of 300 m. Although there are some differences depending on the type and particle size of the conductive filler used, as well as the type of resin, viscosity, and curing characteristics, the length of one side of the projected surface of the molded product 1) and the thickness (d) When the ratio (t/d) of
For example, it was found that smearing and defective nests occurred.

Here, t/d = 75 means that when the projection surface is square, the length of each side is 150 mm and the thickness is 2 m, and when the projection surface is a circle, the diameter of the circle is 150 m and the thickness is 2 WI. It means something. That is, when the thickness is constant at 2 m, if the length of the negative side exceeds 150 m, problems will arise in the molding process.

Also, of course, the larger the tld ratio, the more
Warp deformation tends to increase, and the strength of the product also tends to decrease.

The present inventor has solved the problem of deterioration of flow characteristics, which is a problem when molding products with a large projected area but a small wall thickness, especially when molding materials containing a large amount of conductive filler are required to have a conductive function. We have discovered that the difficulty of molding due to the deterioration of the flow characteristics of the material can be solved by dividing the molded part into a molded part and the substrate that holds the molded part, and by reducing the area of the molded part. In addition, by separating the molded part and the substrate in this way, the molded part can contain a large amount of conductive filler, which can improve the conductive performance and reduce the strength and warpage of the product. The results showed that the improvement was due to the skeletal structure.

Therefore, according to the present invention, a hole of an appropriate shape and size is made in a substrate with a t/d of 75 or more, and a molded part with a tld ratio of 75 or less is held in this hole by a molding material containing a conductive filler dispersed therein. A composite conductive molded article made by molding is provided.

Examples of the conductive filler used in the present invention include powdered or fibrous materials such as graphite, carbon black, and conductive metals, as well as glass fibers coated with metals such as phenol resins, polyester resins, epoxy resins, silicone resins, etc. Thermoplastic resins such as diallyl phthalate resin, melamine resin, polyimide resin, etc., such as fluororesin, polyethylene, polypropylene, polyamide, polyester, polystyrene, polyvinyl chloride, acrylic resin, ABS, As
resin, polycarbonate resin, polyphenylene oxide resin, ethylene, vinyl acetate copolymer, etc., but in the present invention, it is possible to add a large amount, that is, up to 90 parts by weight.

As the substrate material used in the present invention, from the viewpoint of molding processing, it is most preferable to use a plate material with high rigidity, but under conditions such as a small wall thickness and a low molding pressure, rigidity may not necessarily be sufficient. Not necessary1. Therefore, many plate materials can be used by considering the forming processing conditions and application conditions.

For example, a plate made of thermosetting resin, thermoplastic resin, rubber, or metal, or an inorganic plate such as a ceramic plate can be used as the substrate. The board is
Depending on the purpose, it does not need to be an insulator and may be conductive.

To hold and mold the conductive filler-dispersed molding material onto the substrate, punch holes of appropriate shapes and dimensions are formed at appropriate positions on the substrate, this is placed in a molding die, and the molding material is placed in the punched holes. This is done by compression molding. Therefore, it is important that the molded part tightly or adheres to the hole-drilled portion of the substrate. For this purpose, measures such as providing an undercut structure on the side wall of the hole and applying adhesive are taken. Compression molding is carried out in consideration of the shape and size of the molded product, the type and amount of the resin component used, and other conditions. These molding conditions can be easily set by those skilled in the art.

i94 Hereinafter, the present invention will be explained with reference to its implementation.

Here, in order to explain the present invention, FIGS. 1(a) and (b)
) A composite plate-like conductive molded product was made as shown in (). In FIG. 1, (a) is a plan view of the molded product according to the present invention, (
b) is a cross-sectional view thereof, where 1 is the substrate and 2 is the conductive molded part.

A hole (4≧t2, tl/d≦75) with an appropriate shape and size is made on the substrate (z/d 275) shown in Fig. 1, and a conductive molded part with an appropriate shape and size is formed in this hole. The aim is to obtain a composite conductive molded product by this method.

Example 1 Phenolic resin laminate 500 x 500 x 2 w
Square hole 100 x 100' for molded part in m
A molded part on the substrate was constructed by opening nine X 2■ square holes at equal intervals (-). An uncured phenol resin was applied as an adhesive to the cut surface of this square hole.

Graphite as a conductive filler (Nippon Carbon l, GA-3
) and 20% by weight of phenolic resin as the resin component.
A conductive graphite dispersion molding material was prepared by adding stearic acid as a mold release agent by weight%.

The above substrate and molding material were placed in a mold capable of molding the shape and dimensions shown in Figure 1, and compression molded to obtain a conductive plate-shaped product.11 Compression molding conditions were as follows: temperature 170
±5°C, molding pressure 150 Kg/d, and curing time 10-. The specific resistance of the molded part was 1X10'' Ω. The strength of the molded product was good because it was composited with the phenolic resin laminate, and almost no warping was observed.

Comparative Example 1 A molding experiment was conducted using only a graphite-dispersed phenolic resin molding material for a square molded product with a t of 500 wm and d of 2 square with ribs on the top and bottom surfaces as shown in FIG.

Addition amount of graphite (Nippon Carbon, GA-3) was 50゜ω.
A graphite-dispersed phenolic resin molding material was prepared using 70.75 and auxiliary equipment, and the molded product as described above was molded. When the molded products were inspected, it was confirmed that as the amount of graphite added increased, good products were no longer obtained, and when the amount added exceeded 70% by weight, the number of defective products exceeded (1)%. In particular, at 80% by weight, it was difficult to obtain a perfectly good product, and some of the molded products had scratches and cavities due to insufficient flow of the material.

In order to obtain perfectly good products, a more precise method of placing materials in the mold is required.

Moreover, the obtained molded product showed considerable warpage deformation. This molded product was placed on a surface plate, and the gap between the molded product and the surface plate was measured and found to be in the range of 13.5 W+ to 5+ am. It was observed that this value tended to decrease as the amount of graphite added increased.

Further, a test piece was cut out from the obtained molded product and its strength was measured.The bending strength was in the range of 6 to 6, and it became brittle and showed a tendency to decrease as the amount of graphite added increased. Specific resistance (Ω-α) is 1 when graphite is 50% by weight.
, 5~2x10°, 2x10-1 for 60% graphite by weight
, 5X10' for 70% graphite by weight, 2-3 X 10' for 75% graphite by weight, O19 for weight% by graphite
~l×10−2 was shown.

As described above, according to the present invention, the conductive plate-shaped molded product of Example 1 is much cheaper than that of Comparative Example 1, and its yield and the resulting conductive performance are also considerably superior. Also,
A commercially available conductive plate, for example, one obtained by machining a resin-impregnated graphite sintered body, can be provided at a much lower cost.

[Brief explanation of the drawing]

FIG. 1 shows an example of a composite plate-like conductive molded product according to the present invention, in which (a) is a plan view and (b) is a cross-sectional view. Here, 1 is the substrate and 2 is the molded part.

Claims (1)

[Claims] 1) The length of one side of the projection surface /=1 and the thickness (dlO ratio (t
/d) A hole of an appropriate shape and size is made at an appropriate position in a substrate with an /d ratio of 75 or more, and a molded part with an /l/d ratio of 75 or less is molded in this location using a molding material in which a conductive filler is dispersed. A composite conductive molded product made by 2) In the composite conductive molded article according to claim 1, the conductive filler-dispersed molding material contains graphite, carbon black, a powdered or fibrous conductive metal as the conductive filler. 1. A composite conductive molded product characterized by using a thermosetting resin, thermoplastic resin, or rubber as a resin component. 3) The composite conductive molded article according to claim 1 or 2, characterized in that the content of the conductive filler is 6)% by weight or more. 4) The composite conductive molded product according to claim 1, wherein the substrate is an insulating or conductive plate made of thermosetting resin, thermoplastic resin, rubber, or metal. Molded products.