JPH0571740B2 - - 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 100 parts by weight of a polymer component containing 95-20% by weight of a polyvinyl chloride resin and 5-80% by weight of an acrylonitrile-butadiene copolymer. A first sheet made of a resin composition containing 5 to 100 parts by weight of phosphate ester and a small amount of lithium chloride, and a rubber or plastic 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, the polyvinyl chloride resin may be any resin that normally contains 50% by weight or more of vinyl chloride, such as a polymer of vinyl chloride, or a copolymer of vinyl chloride and a monomer copolymerizable therewith. Alternatively, it may be a graft copolymer with other resin materials. The average degree of polymerization of the polyvinyl chloride resin is not particularly limited, but is preferably 2000 or more for good mechanical strength. There are no particular restrictions on the acrylonitrile-butadiene copolymer, but one with a high acrylonitrile content is desirable from the viewpoint of compatibility with phosphate esters, and the molecular weight and presence or absence of partial crosslinking will depend on the intended use. It is best to make a selection. The content ratio of the polyvinyl chloride resin and the acrylonitrile-butadiene copolymer is preferably in the range of 95 to 20/5 to 80 in weight ratio of the polyvinyl chloride resin/acrylonitrile-butadiene copolymer.
If the acrylonitrile-butane diene copolymer is less than 5% by weight, the compatibility with the phosphate ester will be poor, and it will be necessary to keep the amount of the phosphate ester low from the viewpoint of bleeding, and the desired conductivity will not be achieved. There is a tendency to become less able to do so. 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, but one that is liquid at room temperature and has low volatility is desirable. For example, tricresyl phosphate, cresyl diphenyl phosphate, di(2,3-dibromopropyl) 2,3-dichloropropyl phosphate, di(2-ethylhexyl) phosphate,
Dioctyl phosphate, triamyl phosphate, tributoxyethyl phosphate, tri(2-chloroethyl) phosphate, tri(chloropropyl) phosphate, tricresyl phosphate, tri(2,3 phosphate) -dibromopropyl) ester, phosphoric acid tri(dichloropropyl) ester, etc. The amount of phosphoric acid ester added to the polymer component containing polyvinyl chloride resin and acrylonitrile-butadiene copolymer is not particularly limited as long as the desired volume resistivity is obtained;
The range of 5 to 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. Lithium chloride is preferably a powder of 80 mesh or less. Lithium chloride is slightly deliquescent and tends to clump, so it is sometimes mixed with powders such as alumina powder or quartz powder, but it is also possible to add such mixtures as they are as a compounding agent. be. 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 evaluating the volume resistivity, surface resistivity, and presence or absence of bleeding for this sheet were evaluated in the first stage.
Shown in the bottom column of the table. The volume resistivity and surface resistivity were each measured based on the Japan Rubber Association standard SPIS2304 and its commentary, 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 4 falling within the scope of the present invention
In all cases, the electrical resistance has been significantly lowered due to the addition of lithium chloride, making them perfect for preventing electrostatic charging. Comparative Examples 1 to 4 all show examples in which lithium chloride is not used, and the electrical resistance is large and a good antistatic effect cannot be expected. Comparative Example 5 uses polyvinyl chloride alone, but it cannot be used because of severe bleeding. Example 5 As shown in FIG. 1, a 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 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 5, 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 5 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 drawings]

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. 5 to 100 parts by weight of a phosphoric acid ester and a small amount of lithium chloride were added to 100 parts by weight of a polymer component containing 95 to 20% by weight of a polyvinyl chloride resin and 5 to 80% by weight of an acrylonitrile-butadiene copolymer. a first sheet made of a resin composition; and a 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, which has higher conductivity than the first sheet. A conductive floor sheet characterized by being formed by laminating a second sheet.