JPS634796B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an antistatic plastic composite sheet having a laminated composite structure of conductive plastic sheets containing a conductive oxide such as conductive zinc oxide with a carbon layer interposed therebetween.

In recent years, plastic sheets with decorative patterns have been widely used as flooring and wall covering materials.
As is well known, plastic sheets such as polyvinyl chloride resin sheets are easily charged with static electricity generated by friction, so dust and dirt can adhere to them, and when the amount of charge increases, it can be discharged to the earth through the human body etc. Therefore, there are problems such as providing an electrical shock.

For this reason, conventional methods have been proposed: (a) applying an antistatic agent to the surface of a plastic sheet, (b) incorporating an antistatic agent into the plastic sheet, and (c) adding carbon black, a conductive material, to the plastic sheet. Methods such as ``containing'' have been generally adopted.

However, method (a) above has the disadvantage of durability in that the coated layer of antistatic agent wears out within a relatively short period of time and loses its antistatic effect, and method (b) above Although it has good durability, there are significant restrictions on the type and amount of antistatic agent used from the viewpoint of moldability, so in reality it is difficult to sufficiently reduce the surface resistivity of plastic sheets, and it is difficult to achieve a satisfactory result. There is a drawback that antistatic effect cannot be expected, and in addition, method (c) above has a high content of carbon black, so there is no problem when manufacturing black plastic sheets.
If it is colored with other colors, it will become dark and dirty, and it will become dark and dirty. However, there were drawbacks such as the fact that it was completely impossible to color the product in colors such as pink, pink, pink, white, etc.

Therefore, in order to solve this problem, the present applicant first filed Japanese Patent Application No. 56-205624 and Japanese Patent Application No. 57-2056.
- In No. 229110, we proposed an antistatic plastic sheet (hereinafter referred to as "conductive sheet" in the present invention) with extremely low surface resistivity, which is made by containing a conductive oxide such as conductive zinc oxide in a thermoplastic resin. .

The conductive sheet according to this proposal has a better antistatic effect than conventional plastic sheets that have been subjected to antistatic treatment, and the conductive oxide it contains is pale blue to white powder. This has the advantage that colorful patterns can be applied without adversely affecting the coloring of the sheet.

The present invention is a plastic sheet with a composite structure made using such a conductive sheet,
The objective is to provide a composite plastic sheet with excellent antistatic properties, colorability, durability, etc.

The basic structure of the plastic sheet of the present invention is:
As shown in FIGS. 1 and 2, the conductive sheets 2 and 2 mentioned above are placed above and below the carbon fiber layer 1.
The carbon fiber layer 1 forming the intermediate layer is
It is formed using carbon nonwoven fabric or carbon woven fabric.

The conductive sheets 2, 2 are made of polyvinyl chloride resin,
Conductive zinc oxide,
It is formed by containing 70 to 90% by weight of a conductive oxide such as conductive titanium oxide, conductive tin oxide, or conductive antimony oxide, and the conductive oxide contained in such a conductive sheet These particles form a complete chain or an incomplete chain with a partially missing part within a few angstroms, and this complete or incomplete chain is used as a conductive path to release frictional static electricity to the outside. It is thought that it exhibits a good antistatic effect.

Next, each conductive oxide contained in the conductive sheet will be explained.

First, conductive zinc oxide is prepared by adding an organic aluminum compound containing an aluminum atom (for example, aluminum salt of carboxylic acid, aluminum alkoxide, aluminum complex salts, etc.)
A mixture of 0.05 to 5 moles of about 800
The conductive zinc oxide thus obtained is generally manufactured by heating and firing at a temperature of ~1100°C and then pulverizing, or by a similar method. ~Several tens of Ωcm
It is a white powder that has a low resistivity and does not affect coloring.

Therefore, by kneading an appropriate amount of a coloring agent therein, it is possible to color the conductive sheet not only in a bright pale color but also in a desired vivid color.

In addition, conductive titanium oxide is produced by heating titanium and titanium oxide to 1550 to 1750°C (vacuum), firing them, and then pulverizing them, or by a similar method. obtained by

Furthermore, conductive tin oxide or conductive antimony oxide can be manufactured by igniting naturally occurring ores such as cassiterite or diantimony tetroxide in air, or by a similar method. These are all generally several Ωcm
It forms pale blue to white powder particles with a low resistivity of ~ several tens of Ωcm.

In this way, the above-mentioned conductive oxides are pale blue to white powder particles that do not have a negative effect on coloring, so by kneading an appropriate amount of coloring agent, the conductive sheet can be made into It is possible to color not only bright pale colors but also vivid and colorful desired colors.

In general, with plastic sheets used for floor coverings and wall coverings, static electricity generated by friction has no place to escape and becomes charged on the surface of the sheet, so dust and dust in the air can become charged and adhere to it due to electrostatic induction. A discharge shock is given to the human body by the charged electric charge flowing through the human body and into the earth with a low potential.According to the experimental results of the present inventors, in the case of a thermoplastic resin sheet, the surface If the specific resistance is about 10Ω, no harmful effects due to static electricity will be observed, and if the content of the conductive oxide is about 70 to 90% by weight of the total in the thermoplastic resin, the above range will be achieved. It was confirmed that a surface resistivity of .

In other words, if the content of the conductive oxide in the thermoplastic resin is less than 70% by weight, the surface resistivity of the conductive sheet will be greater than the above range, making it difficult to exhibit a good antistatic effect, and vice versa. It was confirmed that when the amount exceeds 90% by weight, the strength becomes too weak to be used as flooring or wall covering materials.

Also, regarding the fact that if the content of conductive oxides etc. is less than 70% by weight, the surface resistivity increases and a good antistatic effect cannot be obtained.
It is inferred that due to the lack of conductive oxide, the aforementioned complete or incomplete chains, which provide electrostatic conduction paths, are not sufficiently formed within the plastic sheets.

However, according to the composite sheet of the present invention, the surface of the sheet where frictional static electricity is likely to be generated is formed of a conductive sheet that has a significantly lower surface resistivity than conventional plastic sheets, and there is an even greater distance between these two sheets. Since a carbon layer, which is a good conductor with low surface resistivity, is interposed in the sheet, the electric charge generated on the surface of the sheet escapes to the ground through the inside of the sheet, and it is thought that almost no charging phenomenon occurs.

The composite sheet of the present invention is produced by adding any of the conductive oxides produced as described above, or an arbitrary mixture thereof, to the main thermoplastic resin, as a plasticizer, a stabilizer, and a colorant. The material is prepared by mixing and kneading it with various auxiliary materials such as agents, and then molding this material by a desired molding method such as extrusion molding or press molding. A conductive sheet is manufactured into a laminated structure by interposing a carbon nonwoven fabric or the like and integrating the conductive sheet with thermocompression using a method such as a pressure roll or multistage press processing.

Here, the thermoplastic resin that forms the base material of the conductive sheet includes electrically charged resins such as polyvinyl chloride resin, polyethylene resin, polypropylene resin, ethylene vinyl acetate copolymer resin, polymethyl methacrylate resin, polycarbonate resin, and cellulose resin. Any thermoplastic resin that is easy to use can be used, and any of the various auxiliary materials commonly used for conventional thermoplastic resins such as plasticizers, stabilizers, and colorants can be used. Needless to say, it is.

As detailed above, the plastic composite sheet according to the present invention is made by laminating conductive sheets, which have a significantly lower surface resistivity than conventional plastic sheets, with a carbon fiber layer having an even lower surface resistivity interposed therebetween. Since it is a composite structure, it has extremely good antistatic properties, making it extremely useful for use as floor coverings and wall coverings in environments where the generation of dust and static electricity is extremely averse. It is.

In addition, the conductive sheet that forms the surface of the composite sheet contains a conductive oxide in the form of light blue to white powder that does not affect the coloring of the sheet. By kneading the coloring agent, it is possible to color the plastic sheet in a desired bright color, thereby making it possible to obtain a plastic sheet with a colorful decorative pattern.

Finally, examples will be given.

Example 1 100 parts of polyvinyl chloride resin (parts by weight, same below), 60 parts of DOP, 3 parts of stabilizer, conductive zinc oxide
400 parts and 1 part of pigment (phthalocyanine mixed pigment) were kneaded and extruded to produce an antistatic polyvinyl chloride sheet (thickness 1.5 mm) with a conductive zinc oxide content of approximately 72% by weight. did.

Two of the obtained conductive sheets were thermocompressed and bonded together with a carbon nonwoven fabric (50 g/m ² ) interposed therebetween. The thus obtained three-layer composite sheet had a bright blue-green color with no turbidity on its surface, and its surface resistivity was approximately 9.6×10 ⁶ Ω, exhibiting good antistatic properties.

Example 2 An antistatic polyvinyl chloride resin sheet (thickness: 1.5 mm) containing approximately 80% by weight of conductive zinc oxide was produced in the same manner as in Example 1 except that the amount of conductive zinc oxide was changed to 600 parts. ) were integrally bonded by thermocompression with a carbon nonwoven fabric (20 g/m ² ) interposed therebetween.

As in Example 1, the thus obtained composite sheet with a three-layer structure exhibits a bright blue-green color with no turbidity on the surface, and its surface resistivity is approximately 1.1×.
The resistance was 10 ⁷ Ω, exhibiting good antistatic properties.

Example 3 The content of conductive titanium oxide was approximately 80% by weight, which was produced in the same manner as in Example 1 except that the amount of conductive zinc oxide was changed to 800 parts and 1 part of Bengara pigment was added as a coloring agent. A plurality of antistatic polyvinyl chloride sheets (thickness: 1.5 mm) were used, and a carbon nonwoven fabric (20 g/m ² ) was interposed between each sheet, and the sheets were bonded together by thermocompression.

As in Example 1, the thus obtained multilayered composite sheet exhibits a bright blue-green color with no turbidity on its surface, and its surface resistivity is approximately 1.1×.
The resistance was 10 ⁷ Ω, exhibiting good antistatic properties.

Example 4 100 parts of polyvinyl chloride resin (parts by weight, same below), 50 parts of DOP, 3 parts of stabilizer, conductive titanium oxide
Antistatic polyvinyl chloride resin sheet (thickness 1.5 mm) containing approximately 72% by weight of conductive titanium oxide, manufactured by kneading 400 parts of pigment and 1 part of pigment (phthalocyanine mixed pigment) and extrusion molding. ) was manufactured.

Two of the obtained sheets were thermocompressed and bonded together with a carbon nonwoven fabric (20 g/m ² ) interposed therebetween.
As in Example 1, the thus obtained composite sheet with a three-layer structure exhibits a bright blue-green color with no turbidity on the surface, and its surface resistivity is approximately 1.2×10 ⁷
Ω, exhibiting good antistatic properties.

Example 5 An antistatic polyvinyl chloride resin sheet (thickness 1.5 mm) containing about 80% by weight of conductive titanium oxide was prepared in the same manner as in Example 1 except that the amount of conductive titanium oxide was changed to 600 parts. Obtained.

Two of the obtained sheets were thermocompressed and bonded together with a carbon nonwoven fabric (20 g/m ² ) interposed therebetween.

As in Example 1, the thus obtained composite sheet with a three-layer structure exhibits a bright blue-green color with no turbidity on the surface, and its surface resistivity is approximately 1.4×
The resistance was 10 ⁷ Ω, exhibiting good antistatic properties.

Example 6 Conductive titanium oxide was produced in the same manner as in Example 1 except that the amount of conductive titanium oxide was changed to 800 parts and 1 part of Bengara pigment was added as a coloring agent.The content of conductive titanium oxide was about 84% by weight. An antistatic polyvinyl chloride resin sheet (thickness 1.5 mm) was manufactured.

Two of the obtained sheets were thermocompressed and bonded together with a carbon nonwoven fabric (20 g/m ² ) interposed therebetween.
As in Example 1, the thus obtained composite sheet with a three-layer structure exhibits a bright blue-green color with no turbidity on the surface, and its surface resistivity is approximately 1.1×10 ⁷
It exhibited good antistatic properties at Ω.

Examples of conductive tin oxide and conductive antimony oxide, as well as conductive products manufactured by containing 70 to 90% by weight of a mixture of any of the above-mentioned conductive oxides in a thermoplastic resin. Although a description of the examples manufactured using the adhesive sheet will be omitted, the same effects as the above-mentioned examples were obtained in all cases.

[Brief explanation of the drawing]

FIG. 1 is a schematic longitudinal cross-sectional view showing one embodiment of the plastic composite sheet of the present invention, and FIG. 2 is a schematic longitudinal cross-sectional view showing another embodiment thereof.

Claims (1)

[Scope of Claims] 1. A conductive sheet comprising conductive zinc oxide, conductive titanium oxide, conductive tin oxide, conductive antimony oxide, or any mixture thereof in a thermoplastic resin, An antistatic plastic composite sheet characterized by being laminated with a carbon fiber layer interposed therebetween. 2 The conductive sheet contains conductive zinc oxide, conductive titanium oxide, conductive tin oxide,
The antistatic plastic composite sheet according to claim 1, which contains 70 to 90% by weight of any conductive antimony oxide or any mixture thereof.