JPH0571741B2 - - 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 adsorption 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 95 to 20% by weight of a copolymer of vinyl chloride and a monomer having an ionic group and a reactive double bond in the molecule, and acrylonitrile. Volume resistivity is ¹⁰⁸ for 100 parts by weight of polymer component containing 5 to 80% by weight of butadiene copolymer.
A first sheet made of a resin composition containing 5 to 100 parts by weight of phosphoric acid ester of Ω-cm or less, and a rubber or plastic containing at least one of carbon black, carbon fiber, metal powder, and metal fiber. It is characterized by laminating a second sheet made of a resin composition and having higher conductivity than the first sheet. 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 0.5 to 20% by weight. If it is less than 0.5% by weight, it tends to be difficult to obtain good electrical resistance, and if it exceeds 20% by weight, the compatibility with the acrylonitrile-butadiene copolymer and phosphoric acid ester becomes poor. Along with this, the mechanical strength tends to decrease. 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. In the present invention, the acrylonitrile-butadiene copolymer is not particularly limited, but it is desirable to have a high acrylonitrile content from the viewpoint of compatibility with the phosphate ester, and the molecular weight and presence or absence of partial crosslinking are not subject to consideration. It is best to select one depending on the intended use. The content ratio of the vinyl chloride copolymer and the acrylonitrile-butadiene copolymer is preferably in the range of 95 to 20/5 to 80 in weight ratio of vinyl chloride copolymer/acrylonitrile-butane diene copolymer. 5% by weight of acrylonitrile-butane diene copolymer
If it is below, the compatibility with the phosphoric ester becomes poor, and it becomes necessary to keep the amount of the phosphoric ester added low from the viewpoint of bleeding, which tends to make it impossible to obtain the desired electrical conductivity. When the acrylonitrile-butane diene copolymer exceeds 80% by weight, raw rubber-like properties become noticeable, resulting in poor processability and a tendency to be unable to obtain a product with a smooth surface.Additionally, vulcanization becomes necessary, increasing the manufacturing process. do. In the present invention, the phosphoric acid ester is not particularly limited in other properties as long as it has a volume resistivity of 10 ⁸ Ω-cm or less, but it is preferably a phosphoric acid ester that 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
Any of ester, tricresyl phosphate, tri(2,3-dibromopropyl) phosphate, tri(dichloropropyl) phosphate, etc. may be used. The amount of phosphate ester added to the polymer component containing vinyl chloride copolymer and acrylonitrile-butadiene copolymer is not particularly limited as long as the desired volume resistivity can be obtained, but it is 5 parts by weight per 100 parts by weight of the polymer component. A range of 100 parts by weight is preferred.
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 a deterioration of the mechanical properties and make them unsuitable for use in the field of thermoplastic resins. Further, a phosphoric acid ester having a volume resistivity of 10 ⁸ Ω-cm or more cannot efficiently lower the electrical resistance. 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 rubber or plastic containing carbon black, carbon fiber, metal powder, metal fiber, etc. to give conductivity, antistatic performance can be further improved, and it is also useful for improving aesthetics. . [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. This sheet was evaluated for volume resistivity, hardness, and the presence or absence of bleeding, and the results are shown in the lower column of Table 1. The volume resistivity is based on the Japan Rubber Association standard specifications.
Based on SRIS2304 and its explanation, hardness was measured using a UF Shore Depth Meter Type A, and bleed was evaluated by observing the surface with the naked eye after leaving it at room temperature for 10 days.

[Table] From Table 1, Examples 1 to 3 falling within the scope of the present invention
All of them have sufficient electrical resistance to prevent electrostatic charging, and their hardness ranges from 68 to 92, which is a relatively wide range. This shows that the hardness can be selected relatively freely depending on the application without sacrificing the antistatic performance. Comparative Examples 1 to 4 all use phosphoric esters whose volume resistivity is greater than the range of the present invention. In Comparative Examples 1 and 2, the composition was 50 parts by weight, but both the volume resistivity and the surface resistivity were large.
Not practical. Although Comparative Example 3 contained 100 parts by weight, twice as much as Comparative Examples 1 and 2, the volume resistivity and surface resistivity did not decrease much, and bleeding was observed. In Comparative Example 4, the amount of acrylonitrile-butane diene copolymer was increased and the amount of phosphoric acid ester was doubled to 200 parts by weight as in Comparative Example 3, but the hardness decreased and it generally became thermoplastic. Not suitable for applications where resin is used. Comparative Example 5 uses a vinyl chloride copolymer alone, but due to insufficient dispersion of the phosphoric acid ester, the volume resistivity and surface resistivity are large, and the occurrence of bleeding is observed. Example 4 As shown in FIG. 1, a sheet in which color conductive layer 1 and conductive layer 2 were laminated was produced. 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 sheet with a colored surface as shown in FIG. 1. Comparative Example 6 Color conductive layer 1 was prepared by adding 100 parts by weight of polyvinyl chloride resin, 50 parts by weight of dioctyl phthalate, 2 parts by weight of a nonionic antistatic agent (Resisit 141, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), and other stable ingredients. A laminated sheet was prepared in the same manner as in Example 4, except that the composition was prepared using a composition containing 6 parts by weight of agents and the like. The results of measuring the electrical resistance of the laminated sheets produced in Example 4 and Comparative Example 6 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 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 sheet of Comparative Example 6 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. To 100 parts by weight of a polymer component containing 95 to 20% by weight of a copolymer of vinyl chloride and a monomer having an ionic group and a reactive double bond in the molecule and 5 to 80% by weight of an acrylonitrile-butadiene copolymer. A first sheet made of a resin composition containing 5 to 100 parts by weight of a phosphoric acid ester having a volume resistivity of 10 ⁸ Ω-cm or less, and rubber or plastic coated with carbon black, carbon fiber, metal powder, and metal fiber. 1. A conductive floor sheet comprising a second sheet made of a resin composition containing at least one of the above, and having a higher conductivity than the first sheet.