JPH0572499B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a conductive floor sheet that can be freely colored and has sufficient antistatic performance. [Prior Art] A measure to prevent static electricity from forming on rubber or plastic molded products is to lower the electrical resistance of the molded product and quickly ground and dissipate static electricity generated by friction. The following methods have been known to lower the electrical resistance of rubber or plastic. (1) A method of adding highly conductive metal powder or fibers such as silver, copper, stainless steel, or nickel to rubber or plastic. (2) A method of adding carbon black or carbon fiber to rubber or plastic. (3) A method of adding surfactants called antistatic agents or similar substances to rubber or plastic. [Problems to be Solved by the Invention] Although the method (1) is very effective in preventing electrostatic charging, it cannot be colored freely and is limited to metallic colors. Moreover, it is very expensive and lacks economic efficiency. Furthermore, it is desirable that the electrical resistance of the molded product be within a certain range to prevent the risk of electric shock due to low-voltage electricity, but it is difficult to stably manufacture such a product using metal powder or metal fiber. is extremely difficult. In method (2), carbon black is often used as an inexpensive conductivity imparting agent, but it has the disadvantage that the hue is limited to black. Moreover, even with this method, it is difficult to industrially and stably produce molded products that are free from the risk of electric shock due to low voltage electricity. Although method (3) has the advantage of being able to be colored freely, it has poor compatibility with rubber and plastic.
This is achieved by incorporating a surfactant that easily absorbs moisture and letting it bleed onto the surface to lower the surface resistance and dissipate static electricity from the surface.It relies on surface resistance, which is electrical resistance that is easily influenced by environmental conditions. and lacks stability in antistatic performance. In particular, the antistatic effect will be considerably reduced in a low humidity environment. Moreover, the duration of antistatic performance is short. On the other hand, in recent years, semiconductor parts such as IC, LSI, and electronic equipment factories are being used to prevent production failures due to the attraction of micron and submicron dust particles due to the generation of static electricity, and in office automation rooms, etc. The use of conductive floors is being considered to prevent computer malfunctions and circuit damage. In this case, from the viewpoint of aesthetics, it is preferable to use a sheet obtained by method (3), which can be colored freely, but it is difficult to use it alone due to concerns about its antistatic performance. As a countermeasure to this problem, it is possible to use a laminated sheet with the sheet obtained by method (3) on the front side and the sheet with high conductivity obtained by method (1) or (2) on the back side. . In such a laminated sheet, static electricity charged on the front side leaks to the conductive layer on the back side and is grounded, but in this case, volume resistance is more important than surface resistance, and surfactants and similar charged A sheet produced by method (3) in which something called an inhibitor is added cannot lower the volume resistivity, and a sufficient antistatic effect cannot be obtained. The present invention has been made based on the above, and aims to provide a conductive floor sheet that can be colored in any color and has excellent antistatic performance. [Means for Solving the Problems] The conductive floor sheet of the present invention comprises a phosphate ester based on 100 parts by weight of a copolymer of vinyl chloride and a monomer having an ionic group and a reactive double bond in the molecule. a first sheet made of a resin composition containing 5 to 100 parts by weight of and 0.01 to 5 parts by weight of an electrolyte, and a rubber or prosthetic containing at least one of carbon black, carbon fiber, metal powder, and metal fiber. It is characterized in that it is formed by laminating a second sheet having higher conductivity than the first sheet made of a resin composition. In the present invention, monomers having an ionic group and a reactive double bond in the molecule to be copolymerized with vinyl chloride include (3-sulfopropyl)-acrylic acid ester potassium salt, (3-sulfopropyl)-acrylic acid ester potassium salt;
-methacrylic acid ester potassium salt, bis(3
-sulfopropyl)-itaconic acid ester potassium salt, N-(3-sulfopropyl)-N-methacroyloxyethyl-N,N-dimethyl-ammonium-betaine, N-(3-sulfopropyl)-N
-Methacroylamidopropyl-N,N-dimethyl-ammonium-betaine, 1-(3-sulfopropyl)-2-vinyl-pyridinium-betaine, and the like. In a copolymer of vinyl chloride and a monomer having an ionic group and a reactive double bond in the molecule (hereinafter referred to as "vinyl chloride copolymer"), the content of the latter monomer is in the range of 5 to 50% by weight. If it is less than 5% by weight, it tends to be difficult to obtain good electrical resistance, and if it exceeds 50% by weight, the compatibility with the phosphate ester tends to deteriorate and the mechanical strength tends to decrease. It is in. The method for obtaining such a vinyl chloride copolymer is not particularly limited, and may be either a suspension polymerization method or an emulsion polymerization method. The properties of the phosphoric acid ester are not particularly limited, but it is desirable that the phosphoric acid ester is liquid at room temperature and has low volatility. For example, cresyl diphenyl phosphate,
Di(2,3-dibromopropyl) 2,3- phosphate
Dichloropropyl ester, di(2-ethylhexyl) phosphate, dioctyl phosphate, triamyl phosphate, tributoxyethyl phosphate, tri(2-chloroethyl) phosphate, tri(chloropropyl) phosphate
Examples include ester, tricresyl phosphate, tri(2,3-dibromopropyl) phosphate, tri(dichloropropyl) phosphate, and the like. The amount of phosphoric acid ester added is preferably in the range of 5 to 100 parts by weight based on 100 parts by weight of the vinyl chloride copolymer. If it is less than 5 parts by weight, it will be difficult to obtain the desired volume resistivity, and if it is about 100 parts by weight, the volume resistivity will be almost saturated. This may lead to deterioration of the mechanical properties and make them unsuitable for use in the field of thermoplastic resins. Examples of the electrolyte include lithium chloride, lithium sulfate, sodium chloride, potassium chloride, magnesium chloride, calcium chloride, zinc chloride, barium chloride, sodium sulfate, potassium sulfate, lithium citrate, and lithium bromide. However, unstable oxidizing or reducing electrolytes such as nitrates or hexavalent chromates are unsuitable for the present invention. The appropriate amount of electrolyte to be added is 0.01 to 5 parts by weight per 100 parts by weight of the vinyl chloride copolymer;
Below parts by weight, there is almost no effect of lowering the electrical resistance, and at 5 parts by weight, the reduction in electrical resistance is almost saturated. In the present invention, in addition to the above ingredients, of course, plasticizers such as DOP, other compounding agents, such as stabilizers, antioxidants, crosslinking agents, vulcanizing agents, vulcanization aids, lubricants, processing aids, flame retardants, fillers, colorants,
Ultraviolet absorbers and the like can be used as appropriate, and the composition can be made without any practical problems. The conductive floor sheet of the present invention includes a sheet made of the above conductive composition, a conventionally known conductive sheet,
In other words, by laminating rubber or plastic with a sheet made of carbon black, carbon fiber, metal powder, metal fiber, etc. to give it conductivity, it is possible to further improve the antistatic performance, and it also helps to improve the aesthetic appearance. . [Example] According to the compounding ratios shown in each example in Table 1, a compound was kneaded using two electrically heated rolls and molded using a high-pressure steam press to produce a sheet with a thickness of 1 mm. The results of measuring the volume resistivity of this sheet are shown in the lower column of Table 1. The volume resistivity is based on the Japan Rubber Association standard.
Measured based on SRIS2304 and its explanation.

【table】

[Table] From Table 1, Examples 1 to 4 falling within the scope of the present invention
Both have sufficient electrical resistance to prevent electrostatic charging. In Comparative Examples 1 and 2, polyvinyl chloride resin was
Dioctyl phthalate is used as a plasticizer, and a commercially available antistatic agent is added to it, so the electrical resistance is high and no antistatic effect can be expected. Example 5 As shown in FIG. 1, a floor sheet was prepared in which a color conductive layer 1 and a conductive layer 2 were laminated. Color conductive layer 1 was prepared by kneading a composition containing 1 part by weight of phthalocyanine green, a green colorant, in addition to the composition of Example 1 using two electrically heated rolls.
It was produced by molding it to a thickness of 0.5 mm using a steam press. The conductive layer 2 is made of 100 parts by weight of polyvinyl chloride resin.
A composition containing 70 parts by weight of dioctyl phthalate, 80 parts by weight of carbon black, and 5 parts by weight of other stabilizers was prepared in the same manner as in the case of color conductive layer 1.
It was manufactured by molding to a thickness of 2.5 mm. The volume resistivity of this conductive layer 2 was 3×10 ² Ω-cm. Next, the colored conductive layer 1 and the conductive layer 2 were laminated using a steam press to produce a laminated floor sheet with a colored surface as shown in FIG. 1. Comparative Example 3 Color conductive layer 1 was prepared by adding 100 parts by weight of polyvinyl chloride resin, 50 parts by weight of dioctyl phthalate, and a nonionic antistatic agent (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., Resistant).
141) A laminated floor sheet was produced in the same manner as in Example 5, except that it was produced using a composition containing 2 parts by weight and 6 parts by weight of other stabilizers and the like. The results of measuring the electrical resistance of the laminated floor sheets produced in Example 5 and Comparative Example 3 are shown in Table 2. The electrical resistance was measured as shown in FIG. That is, a voltage is applied to the copper plate 4 connected to the conductive layer 2 using the DC power supply 5, and the diameter of 60mmφ is
The current flowing through the electrode 3 was measured with an ammeter 7, and the electrical resistance was calculated from Ohm's law. 6 is a voltmeter.

[Table] The laminated floor sheet of Comparative Example 3 had high electrical resistance, and the lamination effect was not exhibited. [Effects of the Invention] As explained above, according to the present invention, it is possible to realize a conductive floor sheet that can be colored in any color and has excellent antistatic performance.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of one embodiment of the conductive floor sheet of the present invention, and FIG. 2 is an explanatory diagram of a method for measuring the electrical resistance of the conductive floor sheet. 1: Conductive colored sheet, 2: Conductive sheet.

Claims (1)

[Claims] 1. A resin containing 5 to 100 parts by weight of a phosphoric acid ester and 0.01 to 5 parts by weight of an electrolyte based on 100 parts by weight of a copolymer of vinyl chloride and a monomer having an ionic group and a reactive double bond in the molecule. a first sheet made of a composition, and a second sheet having higher conductivity than the first sheet made of a resin composition made of rubber or plastic containing at least one of carbon black, carbon fiber, metal powder, and metal fiber. A conductive floor sheet characterized by being made by laminating two sheets.