JPS61135196A - Electroconductive sheet for thermosetting resin molding - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a conductive sheet for molding thermosetting resins such as radio wave shielding materials and radio wave reflecting materials (hereinafter referred to as conductive sheet). It is widely used in OA equipment with a built-in CPU and parabolic antennas for satellite broadcasting.

(Prior art) As a prior art related to the present invention, Japanese Patent Application Laid-Open No. 57-16041
There is a publication titled ``Resin Composite Material for Conductive Molding'', which is a composite material in which short carbon fibers and conductive carbon black are mixed together with a polypropylene matrix, and it has excellent electrical properties and mechanical properties. It is disclosed that the properties are excellent.

(Problems to be Solved by the Invention) However, in the conductive resin composite materials as described above, the conductive filler is mixed uniformly throughout the entire resin, that is, from the surface to the inside, so filler contamination may occur. The amount is large, and when short metal fibers are used as the conductive filler, the weight becomes heavy, and it is extremely difficult to continuously knead the resin and metal fibers without breaking the fibers. . Furthermore, resin materials containing a large amount of conductive filler have poor moldability and are expensive.

Therefore, the technical object of the present invention is to provide a conductive sheet with good shielding properties by reducing the amount of metal fibers used in the conductive sheet and uniformly dispersing the short metal fibers so that they do not break. It is.

[Structure of the invention]

(Means for solving the problem) The measures taken to solve the above technical problem are as follows:
．． 1 short metal fiber made of aluminum alloy or copper alloy with 5 to 6 fins and a diameter of 20 to 100 μm per square meter.
Distribute 00 to 600g uniformly by hand or using a dropping device,
A short metal fiber sheet material is created by spraying an adhesive dissolved in a solvent and drying and solidifying it under pressure at a constant temperature.This short metal fiber sheet material is mixed with 100 parts of unsaturated polyester resin and 100 parts of glass fiber. Calcium carbonate 10 as a bulking agent
0 parts, 2 to 5 parts of magnesium oxide as a thickener, and a sheet molding compound (SMC) consisting of an anti-static agent, laminated and pressed at a constant temperature to form a conductive sheet. It is manufactured.

(Operation) The above technical means operates as follows. In other words, the metal fiber sheet, in which short metal fibers made of copper alloy or aluminum alloy are dispersed at a constant density, has no bending or breakage, and has a constant length and thickness because there is no crosstalk process using resin. The metal short fibers in the center are arranged in a mesh pattern to form a metal fiber sheet, which is sandwiched and laminated with unsaturated polyester resin, etc., so the amount of metal short fibers used is limited to the metal fiber sheet in the center. This is a conductive sheet material that has little variation in radio wave shielding properties or radio wave reflection because it is dispersed uniformly.By further pressing this laminated conductive sheet, it can be used to create cases for office automation equipment or parabolic antennas. It is used after being molded into the shape of.

Metal short fibers with a diameter of 20 μm or less are expensive to manufacture, and metal short fibers with a diameter of 150 μm or more are unsuitable for use as a sheet material for Kinka short fibers because of their large size variations.

(Example) Specific examples and comparative examples according to the present invention will be described.

Example-1 Brass fibers with a length of 3 ml and 60 μm were uniformly dispersed on a Teflon film at a ratio of 600 g/M, and after spraying with a polyvinyl alcohol (PVA) aqueous solution, the fibers were pressed under heat. Metal fiber sheet (300x300m
)It was created.

Next, the sheet was sandwiched between SMCs made of unsaturated polyester, glass fiber, extender, thickener, and antistatic agent, and a conductive sheet was molded at a molding temperature of 150°C and a pressure of 100 kg/-.

Example-2 In Example-1, instead of brass fiber, length 3 and diameter 9 were used.
Aluminum fibers of 0 μm were used and uniformly dispersed at a rate of 150 g/d, and then sandwiched between SMCs to form a conductive sheet.

Comparative Example-1 100 parts of unsaturated polyester resin, 10 parts of calcium carbonate
0 parts, 2 parts of the brass fiber of Example-1 to 100 parts of glass fiber
A conductive sheet made of an unsaturated polyester resin containing 40 parts of magnesium oxide, 1.5 parts of magnesium oxide, and 1 part of a hardening agent, and pressure-molded at 150°C.

Comparative Example-2 50 parts of calcium carbonate, 65 parts of glass fiber, Example 2
A conductive sheet consisting of 60 parts of aluminum fiber and the other amounts being the same as in Comparative Example-1.

The above examples and comparative examples are shown in Table 1.

Table 1 Note 1. The measurement of radio wave shield is based on the 300MHz seed box method.

Note 2. Radio wave 1 return loss (dB) is based on the spatial standing wave method.

〔Effect of the invention〕

The present invention has the following unique effects. In other words, metal powder is used as a conductive filler and mixed with unsaturated polyester resin to create SMC, and a laminated structure of this material requires an extremely large amount of filler to ensure shielding performance and radio wave reflection performance. A certain amount of metal powder is required, but by providing the gold M fiber sheet almost in the center of the laminate as in the present invention, the amount of conductive filler is reduced, making it lighter and cheaper, and the laminate also has better colorability. It has good properties and improved mechanical properties.

Claims (1)

[Claims] A sheet made of short metal fibers made of aluminum alloy or copper alloy with a length of 1.5 to 6 mm and a diameter of 20 to 100 μm, uniformly dispersed at 100 to 600 g per square meter and fixed to an adhesive, A conductive sheet for thermosetting resin molding made of unsaturated polyester resin, glass fiber, extender, thickener, and antistatic material, sandwiched and laminated with sheet molding compound.