JPH02255330A - Sheetlike material of thermoplastic resin - Google Patents

Abstract

PURPOSE:To make antistatic performance and shock resistance excellent and furthermore to prevent deterioration in antistatic performance and shock resistance after bending by allowing core-sheathed composite fiber to exist in such a state that it is continued to the other end from one end of a sheetlike material. CONSTITUTION:Knitted fabric or woven fabric is obtained by knitting or weaving core-sheathed composite fiber incorporating electrically-conductive substance in a core into nonconductive fiber at <=30mm interval of fiber. A sheetlike material is formed by arranging at least one layer of this knitted fabric or woven fabric into a sheet made of thermoplastic resin. This core-sheathed composite fiber exists in such a state that it is continued to the other end from one end of the sheetlike material. The core-sheathed composite fiber is constituted by utilizing e.g. a fiber formable polymer as a sheath component and utilizing a polymer incorporating about 15-50wt.% electrically-conductive substance as a core component. In order to exhibit antistatic performance as the sheetlike material, electric resistance is preferably regulated to <=10<8>OMEGAcm. Polyolefine- based resin is preferably utilized as thermoplastic resin from economic and easiness view point for molding it into the sheetlike material.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a thermoplastic resin sheet. The thermoplastic resin sheet provided by the present invention has excellent antistatic performance and impact resistance, and is used in electrical/electronic parts, automobile parts, mechanical parts, building materials, food-related fields, etc.

[Prior Art] Conventionally, in order to prevent static electricity in a sheet-like object made of a thermoplastic resin, a method has generally been used in which an antistatic agent or a conductive filler is blended into the thermoplastic resin.

Furthermore, an antistatic sheet made of a conductive woven or nonwoven fabric and a synthetic resin has been reported.

(Unexamined Japanese Patent Publication No. 59-212259, Unexamined Japanese Patent Publication No. 60-12
(See Publication No. 7143).

[Problems to be Solved by the Invention] The thermoplastic resin sheet containing the above-mentioned antistatic agent or conductive filler has poor impact resistance, and in particular breaks when subjected to impact from a falling ball, etc. The pieces are easily scattered. In addition, when using an antistatic agent, the antistatic agent bleeds out during long-term use, reducing the antistatic performance and increasing the tackiness of the sheet surface.
There are 0 problems while attaching surrounding dust particles. On the other hand, when a conductive filler is blended, a large amount of conductive filler is required to achieve antistatic performance, resulting in problems such as poor economic efficiency, deterioration of mechanical properties, and difficulty in coloring. .

In addition, with the above-mentioned conductive woven or nonwoven fabric sheets, the discharge from the edge of the sheet to prevent static electricity is insufficient, and a large amount of charge accumulated in the sheet is discharged at once, resulting in electric shock. There are problems such as the amount of conductive material used in the entire sheet is relatively large, making it less economical.

Therefore, the object of the present invention is to provide a sheet-like product which has excellent antistatic performance and impact resistance, and whose mechanical performance such as impact resistance and antistatic performance do not deteriorate even after repeated bending, and which can be obtained economically. Our goal is to provide the following.

[Means for Solving the Problem] According to the present invention, the above object is achieved by knitting or mixing a core-sheath composite fiber containing a conductive substance in the core with a non-conductive fiber at a fiber spacing of 30 mm or less. A sheet-like article in which the obtained knitted or woven fabric is arranged in at least one layer within a sheet made of a thermoplastic resin, and the core-sheath composite fibers are present in a continuous state from one end of the sheet-like article to the other end. This is achieved by providing a sheet-like product that

The knitted or woven fabric used in the present invention is a mixture of a core-sheath composite fiber containing a conductive substance in the core (hereinafter referred to as a core-sheath composite fiber) and a non-conductive fiber. This is what was obtained. The core-sheath composite fibers and non-conductive fibers may be in the form of fiber bundles, single yarns, double yarns, spun yarns, aligned yarns, filament yarns, triplet yarns, etc., and their thickness and length It is not limited.

As the core-sheath composite fiber, for example, fiber-forming polymer (A
) is used as a sheath component, and a polymer (B) containing about 15 to 50% by weight of a conductive substance is used as a core component. The weight ratio of the sheath component to the core component is in the range of about 9515 to 7°/30, the number of cores per 'a' fiber is 1 to 8, and the fiber diameter is preferably 404 m or more.

Polyester polymers, polyolefin polymers, etc. are used as the sheath component polymer (A), and polyamide polymers, etc. are used as the core component polymer (B). As the conductive substance, metal powders such as gold, silver, alumina, copper, etc., titanium oxide having lattice defects, metal salts of titanic acid, semiconductor ceramic powders such as Pe30a and Snow, conductive carbon black, etc. are used. The core-sheath composite fiber preferably has an electrical resistance of 101 Ωcm or less in order to exhibit antistatic performance as a sheet-like product.

Non-conductive fibers include glass fiber, natural wt fiber, artificial fiber, synthetic polymer fiber, etc. alone or 2t! Examples include the above-mentioned mixed fibers. From the viewpoint of impact resistance, organic fibers such as natural fibers, artificial fibers, and synthetic polymer fibers are preferred.

The fiber spacing of the core-sheath composite fiber in knitted or woven fabric is 3G.
− Must be less than or equal to one. The more core-sheath composite fibers are included in the knitted or spread fabric, the greater the antistatic effect becomes. The preferred fiber spacing is in the range of 5 to 20 m.

When the fiber spacing exceeds 3 hm, the antistatic effect of the resulting knitted or woven fabric is extremely low.

The method of knitting or blending the core-sheath composite fiber and the non-conductive fiber may be, for example, any method such as plain weave, thread weave, satin weave, leno weave, stockinette knitting, loop knitting, etc. Yuzu is not particularly limited in terms of weft density, diagonal thread density, etc. Plain weave is preferred because it is easy to efficiently arrange the core-sheath composite fibers in the non-conductive fibers. Furthermore, if the mesh size of the knitted or woven fabric is too large, the notching effect will increase, leading to a decrease in performance due to bending, and impact resistance will also decrease, so it is preferable that the fabric weight is 50 g/m'' or more. The knitted or woven fabric may be colored by original dyeing, piece dyeing, or the like, depending on the intended use.

Thermoplastic resins used in the present invention include polyolefin resins such as polyethylene, polypropylene, and poly4-methylpentene, boric ester resins such as polybutylene ethylene leftate, polybutylene ethylene leftate, and boria oxide resins. crystalline thermoplastic resins such as and their copolymers, polystyrene resins,
Examples include non-grade thermoplastic resins such as polyacrylic resins and polycarbonates, copolymers thereof, and alloys of two or more thermoplastic resins, but economic efficiency,
It is preferable to use polyolefin resin because it can be easily formed into a sheet shape. In addition, thermoplastic resins may contain various fillers such as calcium carbonate, mica, talc, glass flakes, glass fibers, and glass peas, as well as various additives such as deterioration inhibitors, ultraviolet absorbers, colorants, and mold release agents. etc. can be blended.

In the present invention, a knitted fabric or woven fabric obtained by knitting or mixing a core-sheath composite fiber with a non-conductive fiber (hereinafter referred to as a conductive knitted/woven fabric) is a thermoplastic It is laminated and fixed in a sheet made of resin to form a sheet-like product.

The conductive knitted or woven fabric may be laminated in multiple layers depending on the thickness of the sheet-like material. Ease of adhesion of dust to the surface of the sheet due to surface roughness, lack of conductive layer, ease of cutting, beauty of the surface of the sheet, ease of coloring, etc. It should be avoided that the surface of the sheet-like material becomes a layer of knitted or woven fabric that has electrical conductivity.

In the sheet-like article of the present invention, it is necessary that the core-sheath composite fiber exists in a continuous state from one end of the sheet-like article to the other end. If the core-sheath composite fiber is cut in the middle of the sheet-like product or is not continuous to the end, the antistatic performance of the sheet-like product is extremely low. In the sheet-like article of the present invention, since the core-sheath composite fiber exists in a continuous state from one end of the sheet-like article to the other end, the electric charge inside the sheet-like article is quickly transferred to the end of the sheet-like article. The tip can be discharged.

The sheet-like product of the present invention is a knitted or woven material having conductivity between sheets made of thermoplastic resin manufactured by a general method such as extrusion molding using a sheet die, calendar molding, press molding, etc. A method of disposing cloth and welding it using a flat plate press or bonding it using an adhesive. Extruder - conductive between sheets of thermoplastic resin in a molten state extruded from a goo using a multilayer rib die. It is manufactured by a melt extrusion method, etc., in which a knitted or woven fabric having a certain property is arranged and welded by roll crimping or belt crimping.

Methods involving heating such as welding using a flat plate press or melt extrusion method are used to maintain the shape of the conductive knitted or woven fabric in the sheet-like material. It is carried out at a temperature below the melting point of the fiber material having the lowest melting point among them, and at a temperature higher than the melting point or softening point of the thermoplastic resin constituting the sheet-like article. Therefore, the melting point of the fiber material is 2 times higher than the melting point or softening point of the thermoplastic resin.
It is not possible to maintain the form of a woven fabric at temperatures below 0°C (this results in a decrease in the impact resistance of the sheet-like material and also a decrease in its mechanical performance due to bending).

[Examples] The present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples. In addition, each physical property of the sheet-like material was measured and determined by the method shown below.

Charge density: Measured in accordance with RIIS-TR-78-1, the static electricity safety guideline issued by the Ministry of Labor's Industrial Safety Research Institute.

Falling ball impact strength: Measured in accordance with J Is K 7211.

Example 1 A fiber bundle consisting of 8 core-sheath composite fibers (manufactured by Kuraray Co., Ltd., Kura Carbo 0) having a conductive substance in the core was woven in one direction between polyethylene tereftate spun yarns at a fiber spacing of 5 cm to form a woven fabric. A plain woven fabric with a basis weight of 100 g/m" was obtained. Commercially available polypropylene resin (manufactured by Ube Industries, Ltd., B-101H) was obtained.
) is supplied to a sheet manufacturing device equipped with two sheet dies, and the sheet is extruded from the two guidies, and the plain woven fabric is inserted between them while the polypropylene is in a molten state to form a roll-pressed sheet. The edges were cut so that the plain woven fabric appeared at the edge of the sheet to obtain a sheet-like product having a thickness of lam. The physical properties of this sheet-like material were measured and the results are shown in Table 1. In addition, a sheet-like material having both ends and using a cloth woven with a core-sheath composite fiber bundle has an antistatic effect when using a small amount of conductive material.

Examples 2 and 3 and Comparative Example 1 In Example 1, the spacing between the core-sheath composite fiber bundles was 1 ha (Example 2), 30 ha (Example 3), or 40 ha (Comparative Example 1)
A plain woven fabric obtained in the same manner except for the following steps was sandwiched between two commercially available polypropylene sheets, and the plain woven fabric and the polypropylene sheet were melt-bonded using a heating plate press, and then cooled to form a plain woven fabric. The woven fabric was cut to a size such that the woven fabric appeared at the edges to obtain a sheet-like product having a thickness of 1 cm. The physical properties of this sheet-like material were measured in the same manner as in Example 1, and the results are shown in Table 1.

It was confirmed that when the distance between the core-sheath composite fiber bundles exceeds 30,011, the antistatic effect of the sheet material is extremely reduced.

Furthermore, it was confirmed that the charge density and falling ball impact strength of the sheet-like material after repeated bending did not decrease compared to before the repeated bending.

Example 4 In Example 2, polypropylene resin (manufactured by Ube Industries, Ltd., B-10) was used instead of the commercially available polypropylene sheet.
18) Mica (manufactured by Kuraray Co., Ltd., Sujirite Mica 2)
A sheet-like product having a thickness of 1IIIm was obtained in the same manner except that a sheet containing 20% by weight of 00HK) was used. The physical properties of this sheet-like material were measured in the same manner as in Example 1, and the results are shown in Table 1.

Comparative Example 2 The physical properties of a commercially available polypropylene sheet having a thickness of lam were measured in the same manner as in Example 1, and the results are shown in Table 1. This sheet had no antistatic effect and was inferior in impact resistance compared to the sheet-like materials obtained in Examples 1 to 4.

Comparative Example 3 In Example 2, a carbon long fiber bundle (manufactured by Asahi Nippon Carbon Fiber Co., Ltd., fiber diameter 'j') was used instead of the core-sheath composite fiber.
A sheet-like material having a thickness of IIIl was obtained in the same manner except that a 100-mm filament was used. The physical properties of this sheet-like material were measured in the same manner as in Example 1, and the results are shown in Table 1.

Both the antistatic performance and the impact resistance of the sheet-like material were almost the same as those of the sheet-like materials obtained in Examples 1 to 4, and the chargeability after repeated bending was extremely reduced. It is presumed that this is because the carbon long fiber bundles were cut due to bending and the antistatic effect was reduced.

Comparative Example 4 3.16% by volume of conductive carbon black (manufactured by Ketchien Black International, Ketchien Black EC) was added to the same polypropylene resin as used in Example 1.
This blend was supplied to the sheet manufacturing apparatus used in Example 1 to obtain an extruded sheet with a thickness of 1--. The physical properties of this sheet were measured in the same manner as in Example 1, and the results are shown in Table 1.

In order to obtain the same antistatic effect as the sheet materials obtained in Examples 1 to 4, it was necessary to add a large amount of conductive carbon black. In addition, the obtained sheet had poor impact resistance, and a decrease in impact resistance and antistatic effect was observed due to repeated bending.

Margin below [Effects of the Invention] According to the present invention, it has excellent antistatic performance and impact resistance,
Furthermore, there is provided a thermoplastic resin sheet that exhibits no deterioration in antistatic performance and impact resistance after bending.

Patent applicant: RiRashi Co., Ltd.

Claims (1)

[Claims] 1. A knitted or woven fabric obtained by knitting or mixing a core-sheath composite fiber containing a conductive substance in the core with a non-conductive fiber at a fiber spacing of 30 mm or less is a thermoplastic A sheet-like article having at least one layer disposed within a sheet made of resin, wherein the core-sheath composite fiber exists in a continuous state from one end of the sheet-like article to the other end. 2. The sheet-like article according to claim 1, wherein the core-sheath composite fiber has an electrical resistance of 10^6 Ωcm or less. 3. The sheet-like article according to claim 1, wherein the thermoplastic resin is a polyolefin.