JPH0576978B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD OF THE INVENTION The present invention relates to a conductive coating composition capable of imparting high conductivity to a soft vinyl chloride resin surface and forming a conductive film with excellent adhesion. TECHNICAL BACKGROUND OF THE INVENTION AND PROBLEMS THEREOF With the recent development of the electronic industry, there has been a demand for imparting electrical conductivity to soft vinyl chloride resins containing plasticizers, such as vinyl chloride films or sheets. For example, conductive and non-static films or sheets are required for clean room curtains in semiconductor manufacturing rooms, and the above-mentioned conductive films or sheets are also required for packaging IC products. ing. By the way, in order to impart conductivity to a film or sheet made of a soft vinyl chloride resin, a conductive coating composition prepared by dispersing or dissolving a conductive powder and a binder resin in an organic solvent is conventionally used to make a film or sheet made of a soft vinyl chloride resin. It has been applied to the surface. The binder resin in the above-mentioned conductive paint is vinyl chloride resin, vinyl acetate resin, or vinyl chloride resin with a polymerization degree of about 400 to 800 and a vinyl acetate content of about 10 to 15 mol%.
Vinyl acetate copolymer resins and the like have been mainly used. When such a conductive coating composition is applied onto a soft vinyl chloride resin to form a conductive coating film, the resulting conductive coating film has good adhesion to the vinyl chloride resin, but Along with this, there was a serious problem that the conductivity decreased significantly. There are various possible causes for this, but according to research by the present inventors, dioctyl phthalate, 2-ethylhexyl phthalate, butyl phthalate, which are contained in the soft vinyl chloride resin as the base material, It is presumed that this is because plasticizers such as tricresyl phosphate migrate to the conductive coating. In order to prevent the plasticizer contained in the soft vinyl chloride resin used as the base material from migrating to the conductive coating, the base material must be treated with a primer prior to forming the conductive coating. Possible methods include applying the binder resin or replacing the binder resin with another resin. However, the method of applying primer treatment to the base material is undesirable because it complicates the process and increases costs, while the method of replacing the binder resin with another resin reduces the adhesion between the conductive coating film and the base material. There was a problem that it was undesirable. The present inventors conducted extensive research to solve the above-mentioned problems, and found that a binder for conductive coating compositions was created by combining a vinyl chloride-vinyl acetate copolymer resin with a specific degree of polymerization and a polyester resin. It was discovered that when used as a resin, it is possible to prevent the plasticizer contained in the base vinyl chloride resin from migrating to the conductive coating film, thereby reducing the conductivity of the conductive coating film. The present invention has now been completed. Purpose of the Invention The present invention aims to solve the problems associated with the prior art as described above. Moreover, it is an object of the present invention to provide a conductive coating composition that can form a conductive coating film with excellent adhesion. Summary of the Invention The conductive coating composition for a soft vinyl chloride resin according to the present invention comprises (a) a conductive powder, and (b) (1) a vinyl chloride-vinyl acetate copolymer having a degree of polymerization of 200 to 1000. A binder resin consisting of a polymer resin and (2) a polyester resin, in which this polyester resin is present in an amount of 5 to 90% by weight based on the total weight of the vinyl chloride-vinyl acetate copolymer resin and this polyester resin. is dissolved or dispersed in an organic solvent, and the (a) conductive powder is a combination of the (a) conductive powder and the above-mentioned conductive powder.
(b) 50.0 to total weight with binder resin
The organic solvent is present in an amount of 85.0% by weight, and the organic solvent is present in an amount of 50 to 95% by weight based on the total amount of the conductive coating composition. In the present invention, a conductive coating film is formed on a soft vinyl chloride resin surface using a conductive coating composition containing a binder resin made of a vinyl chloride-vinyl acetate copolymer resin having a specific degree of polymerization and a polyester resin. Therefore, the plasticizer contained in the soft vinyl chloride resin does not transfer to the conductive coating film, and therefore the conductivity of the conductive coating film does not deteriorate. Moreover, the adhesion of the conductive coating film to the substrate is also good. DETAILED DESCRIPTION OF THE INVENTION The conductive coating composition according to the present invention will be specifically described below. First, the substrate to which the conductive coating composition according to the present invention is applied is a soft vinyl chloride resin. This soft vinyl chloride resin generally contains a plasticizer such as dioctyl phthalate, phthalate (2-ethylhexyl), dibutyl phthalate, or tricresyl phosphate in an amount of 10 to 60% by weight, and is in the form of a film. It can be in any shape such as a sheet. In addition, the base resin for soft vinyl chloride resin is
Although it is a homopolymer of vinyl chloride, it may also be a copolymer of vinyl chloride and other monomers, such as a copolymer of vinyl chloride and vinyl acetate, vinylidene chloride, acrylic ester, acrylonitrile, propylene, etc. In this copolymer, the amount of other monomers copolymerizable with vinyl chloride is preferably 20 mol % or less. The conductive coating composition according to the present invention applied to such a soft vinyl chloride resin is formed by dissolving or dispersing (a) conductive powder and (b) a specific binder resin in an organic solvent. There is. The conductive powder (a) used in the present invention may be any powder that can impart conductivity to the coating film, such as tin oxide, or tin oxide containing antimony, phosphorus, fluorine, zinc, tellurium, bismuth, and cadmium. Powders doped with one or more of the following elements are used. Also used is indium oxide or a powder obtained by doping indium oxide with an element such as tin. Furthermore, titanium oxide powder, zinc oxide powder, conductive metal powder, etc. can also be used. In the present invention, as (b) the binder resin, (1) a vinyl chloride-vinyl acetate copolymer resin having a degree of polymerization of 200 to 1000 and (2) a polyester resin are used in combination. Vinyl chloride used as binder resin
If the degree of polymerization of the vinyl acetate copolymer resin is less than 200, it will not be possible to prevent the plasticizer contained in the base soft vinyl chloride resin from migrating into the conductive coating, and therefore the conductivity will be reduced. This is not preferable because the electrical conductivity of the polyester coating film is significantly reduced. On the other hand, if the degree of polymerization exceeds 1000, it is not preferable because the compatibility with the polyester resin is reduced. Furthermore, the vinyl acetate content of the copolymer resin is not particularly limited, but
When the amount is less than 1.0 mol%, the effect of preventing the plasticizer from transferring to the conductive coating film is slightly reduced. On the other hand, if the vinyl acetate content exceeds 7.0 mol %, the transparency of the conductive coating film decreases, so that it cannot be used in applications that require transparency, so its applications are limited. The polyester resin used in the present invention is, for example, a polymer having an ester bond in its molecular skeleton formed by condensation polymerization of a polyhydric alcohol such as ethylene glycol or diethylene glycol, and a polyhydric acid such as terephthalic acid or adipic acid. be. In this way, in the present invention, the binder resin is composed of a vinyl chloride-vinyl acetate copolymer resin having a specific degree of polymerization and a polyester resin. 5 to 90% by weight, preferably 20% by weight based on the total weight of polymer resin and polyester resin
Used in amounts of ~70% by weight. If the amount of polyester resin is less than 5% by weight, it will not be possible to prevent the plasticizer contained in the base soft vinyl chloride resin from migrating to the conductive coating. This is undesirable because the conductivity is markedly reduced. On the other hand, when the amount exceeds 90% by weight, the adhesion between the resulting conductive coating film and the substrate is undesirably reduced. Regarding the mixing ratio of (a) conductive powder and (b) binder resin as described above, (a) conductive powder is (a),
(b) Used in an amount of 50.0 to 85.0% by weight based on the total weight of both. (a) If the amount of conductive powder is less than 50.0% by weight, it is undesirable because the conductivity of the resulting coating film will decrease, while if it exceeds 85.0% by weight, the adhesion between the coating film and the soft vinyl chloride base material will deteriorate. This is not preferable because it lowers the temperature. In the conductive coating composition according to the present invention, the above (a)
The conductive powder and (b) the binder resin, vinyl chloride-vinyl acetate copolymer resin and polyester resin, are dissolved or dispersed in an organic solvent. Any material that can dissolve the polyester resin and polyester resin can be used. Specifically, for example, methyl ethyl ketone, methyl isobutyl ketone, toluene, cyclohexane, etc. are used alone or in combination. Such an organic solvent is used in an amount that provides a viscosity that allows the conductive coating composition to be applied onto a substrate, but generally, it is used in an amount of about 50 to 95% by weight based on the total amount of the coating composition. used in amounts of In the conductive coating composition according to the present invention, the above (a)
In addition to the conductive powder and (b) the binder resin, it is preferable to add a surfactant to improve the dispersibility of the conductive powder and prevent particles from re-agglomerating. , nonionic, cationic, etc. can be widely used. Further, if necessary, ultraviolet absorbers, stabilizers, flame retardants, inorganic fillers, silane coupling agents, titanium coupling agents, etc. can be added to the conductive coating composition. The conductive coating composition according to the present invention is applied onto a substrate made of a soft vinyl chloride resin by a conventional coating method such as a bar coating method, a spray method, a roll coating method, etc., and then dried. A conductive coating film is obtained. Effects of the Invention In the present invention, a conductive coating composition containing a binder resin consisting of a vinyl chloride-vinyl acetate copolymer resin having a specific degree of polymerization and a polyester resin is used to conductively coat a soft vinyl chloride resin. Because a film is formed, the plasticizer contained in the soft vinyl chloride resin does not transfer to the conductive coating.
Therefore, the conductivity of the conductive coating film does not decrease. Moreover, the adhesion between the conductive coating film and the substrate is also good. EXAMPLES The present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples. Example 1 (a) Particle size 0.8μm doped with 10% by weight of antimony
20g of tin oxide powder and (b)(1) polymerization degree is 400,
Vinyl chloride with a vinyl acetate content of 5 mol%
A binder resin consisting of 6.0 g of vinyl acetate copolymer resin and 2.5 g of (2) polyester resin (Vylon 200) was mixed with 71.5 g of a mixed solvent of methyl ethyl ketone and toluene (volume ratio 1/1), and then mixed in a sand mill for 3 A conductive coating composition in which the binder resin was dissolved in the mixed solvent and the tin oxide powder was uniformly dispersed was prepared by time-pulverization and mixing. This coating composition was applied to a soft vinyl chloride film containing 35 PHR of dioctyl phthalate as a plasticizer using a bar coater (#6), left to stand at room temperature for 5 minutes, and then dried at 60°C for 3 minutes. A conductive coating film was obtained. The surface resistance (Ω/□) of the conductive coating film thus obtained was measured using an electrode cell (manufactured by YHD), and the adhesion between the coating film and the substrate was measured using JIS K5400-
Evaluation was carried out by cellotape test and grid test in accordance with 1979. The results are shown in Table 1. Example 2 In Example 1, instead of the vinyl chloride-vinyl acetate copolymer of Example 1, a vinyl chloride-vinyl acetate copolymer resin having a polymerization degree of 1000 and a vinyl acetate content of 5 mol% was used. A conductive coating film was formed in the same manner as in Example 1 except that 6.0 g was used,
Its surface resistance and adhesion were measured. The results are shown in Table 1. Example 3 In Example 1, 8.0 g of vinyl chloride-vinyl acetate copolymer resin with a degree of polymerization of 400 and a vinyl acetate content of 5 mol% was used, and the amount of polyester resin used was 0.5 g. Except for this, a conductive coating film was formed in the same manner as in Example 1, and its surface resistance and adhesion were measured. The results are shown in Table 1. Example 4 In Example 1, 0.8 g of vinyl chloride-vinyl acetate copolymer resin with a degree of polymerization of 400 and a vinyl acetate content of 5 mol% was used, and the amount of polyester resin used was 7.7 g. A conductive coating film was formed in the same manner as in Example 1 except for the above, and its surface resistance and adhesion were measured. The results are shown in Table 1. Example 5 In Example 1, instead of the vinyl chloride-vinyl acetate copolymer of Example 1, a vinyl chloride-vinyl acetate copolymer resin having a degree of polymerization of 200 and a vinyl acetate content of 5 mol% was used. A conductive coating film was formed in the same manner as in Example 1, except that 1.8 g was used, and the amount of polyester resin used was 1.8 g.
Its surface resistance and adhesion were measured. The results are shown in Table 1. Example 6 In Example 1, instead of the tin oxide powder of Example 1, 30 g of indium oxide powder doped with 10% tin and having a particle size of 0.4 μm was used as the conductive powder.
A conductive coating film was formed in the same manner as in Example 1, except that the conductive coating film was used, and its surface resistance and adhesion were measured. The results are shown in Table 1. Comparative Example 1 In Example 1, instead of the vinyl chloride-vinyl acetate copolymer of Example 1, a vinyl chloride-vinyl acetate copolymer resin having a polymerization degree of 150 and a vinyl acetate content of 5 mol% was used. 6.0g was used, and the amount of polyester resin used was 2.5g.
A conductive coating film was formed in the same manner as in Example 1, and its surface resistance and adhesion were measured. The results are shown in Table 1. Comparative Example 2 In Example 1, 8.2 g of vinyl chloride-vinyl acetate copolymer resin with a degree of polymerization of 400 and a vinyl acetate content of 5 mol% was used, and the amount of polyester resin used was 0.3 g. Except for this, a conductive coating film was formed in the same manner as in Example 1, and its surface resistance and adhesion were measured. In this comparative example, the amount of polyester resin in the binder resin is 3.5% by weight. The results are shown in Table 1. Comparative Example 3 In Example 1, 0.5 g of vinyl chloride-vinyl acetate copolymer resin with a polymerization degree of 400 and a vinyl acetate content of 5 mol% was used, and the amount of polyester resin used was 8.0 g. Except for this, a conductive coating film was formed in the same manner as in Example 1, and its surface resistance and adhesion were measured. In this comparative example, the amount of polyester resin in the binder resin is 94% by weight. The results are shown in Table 1.

[Table] Note: ○: No peeling of paint film, ×: Peeling of paint film From this table, it can be seen that vinyl chloride-vinyl acetate copolymer resin with a specific degree of polymerization is used as a binder resin for conductive coating compositions. It can be seen that when used in combination with a polyester resin, the conductivity of the resulting conductive coating film does not decrease, and the adhesion between the conductive coating film and the substrate is also good.

Claims (1)

[Claims] 1 (a) conductive powder, and (b) (1) polymerization degree of 200~
1000, and (2) a polyester resin, and this polyester resin has a weight of 5 to 90% based on the total weight of the vinyl chloride-vinyl acetate copolymer resin and this polyester resin. % of a binder resin is dissolved or dispersed in an organic solvent, wherein the conductive powder (a) is dissolved or dispersed in an organic solvent.
The organic solvent is present in an amount of 50.0 to 85.0% by weight based on the total weight of the conductive powder and the binder resin (b), and the organic solvent is present in an amount of 50 to 95% by weight based on the total weight of the conductive coating composition. A conductive paint composition characterized by: