JPH07126412A - Method of preventing conductive substance from falling from end face of conductive molding - Google Patents

Abstract

PURPOSE:To facilitate the transportation and storage of conductive moldings by treating the end faces of the conductive moldings chemically and smoothening the surfaces to prevent the conductive substance from falling from the end faces. CONSTITUTION:The edge faces of conductive moldings such as conductive tapes, films or sheets are brought into contact with an organic solvent dissolving the faces such as methanol to effect chemical treatment, smoothen the surfaces and prevent the conductive substance from falling from the edge surfaces.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating an end face of a conductive molded article used for transporting and storing precision electronic parts so as to prevent the conductive substance from falling off from the end face.

[0002]

[Prior Art and Problems to be Solved by the Invention]
Conductive molded products are used as packaging materials for precision electronic parts,
When the conductive material is transported or stored, a part of the conductive material may be lost and adhere to the precision circuit, which may cause an accident that short-circuits the precision circuit or damages electronic components.
The lack of such a conductive material is often from the end surface of the molded product. It is presumed that this is because the end face is a face cut by a blade, and thus wear and burr are generated and a part of the end face is likely to be lost. Therefore, a method has been adopted in which substances that are likely to be lost are removed in advance by washing. However, even after washing once, if the end surface is rubbed again, the conductive material will be lost. As a result of diligent studies on such a method for preventing the loss of the conductive substance from the end surface, the present invention has been found out that a method of chemically treating the end surface is effective.

[0003]

The present invention provides the following (1) to
It is composed of (4). (1) A method of chemically treating the end surface of a conductive molded article and smoothing the surface to prevent the conductive material from being lost from the end surface. (2) The method according to item (1) above, wherein the chemical treatment method is to bring the end face into contact with a soluble organic solvent. (3) The method according to the above item (1), characterized in that the method of chemically treating is to apply the coating liquid to the end face. (4) The method according to (1) above, wherein the conductive molded article is a conductive tape, film or sheet. That is, it is a method of chemically treating the end surface of a conductive molded product, preferably a conductive tape, film or sheet, and smoothing the surface to prevent the conductive material from being lost from the end surface. As a treatment method, it is preferable to dissolve a part of the end face with an organic solvent or apply a coating liquid.

Here, the conductive molded product is a powder of a conductive substance such as carbon black or metal for the purpose of preventing the generation of static electricity of a plastic molded product, and is made of a material such as polyvinyl chloride, polyethylene, polypropylene or polystyrene. It is formed by mixing with a molecular compound and molding. As a molding method, extrusion molding, injection molding, compression molding, calender molding and the like can be considered, but the molding method is not particularly limited. The shape of the molded product is not particularly limited, but a tape, film or sheet is preferable.

The term "chemically treating" as used in the present invention means to change the surface state of an electrically conductive molded article by treating the end surface with an organic solvent capable of dissolving the end surface. This is a method distinctly different from physical cleaning, which removes fine particles adhering to the surface. As one of the preferred embodiments, it is contacted by a method such as immersing in an organic solvent or adhering an organic solvent to dissolve, remove or redeposit a part of the polymer compound constituting the molded article existing on the surface. This is a method of smoothing by doing. That is, the more irregular the surface, the larger the specific surface area, and thus the greater the solubility. The convex portion dissolves, and if the solution is dried without removing it, the polymer compound once dissolved precipitates in the concave portion. As a result, a smooth surface is formed. The organic solvent used here should be selected according to the kind of the polymer compound in the electroconductive molded article, taking into consideration its solubility.

The following compounds may be mentioned as specific examples of the organic solvent used in the present invention, but they are not necessarily limited to these. Methyl alcohol, ethyl alcohol, n-propyl alcohol, i-propyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, n-amyl alcohol, i-amyl alcohol, tert-amyl alcohol, n-hexyl alcohol , Alcohols such as cyclohexanol, benzene, toluene, xylene,
Aromatic hydrocarbons or alicyclic compounds such as anisole, tetralin, cyclohexane and decalin, acetic acid esters such as ethyl acetate and butyl acetate, acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-
Ketones such as n-butyl ketone, methyl isobutyl ketone, diethyl ketone, ethyl-n-propyl ketone, di-n-propyl ketone, diisopropyl ketone, di-n-amyl ketone, cyclohexanone, tetrahydrofuran, dioxane, 2-methoxyethanol, 2 -Ethoxyethanol, carbitol, diglyme, triglyme, tetraglyme and other ethers, N, N-dimethylformamide, N, N-dimethylacetamide, N-
Examples thereof include basic compounds such as methyl-2-pyrrolidone.
One or more of these can be appropriately selected and used.

The object can be achieved by bringing the organic solvent into contact with the end surface of the electroconductive molded article and maintaining the temperature at room temperature to the boiling point of the solvent or lower for several minutes to several days.

Another preferred embodiment of the present invention is a method in which a coating solution containing a polymer compound is applied to the end surface of a conductive molded article, and the surface is covered with a thin film for smoothing. The coating liquid used in the present invention is a solution obtained by dissolving or dispersing a high molecular compound such as resin or rubber, an oligomer, a monomer in an organic solvent or water. Of these, polymer compounds are preferred, vinyl chloride resins, acrylic resins,
Polyolefin resin, urethane resin or NB
R, SBR and natural rubber are particularly preferable.

A known method can be applied as a method for applying the coating liquid. For example, a doctor blade coating method, a gravure roll coating method, an air knife coating method, a reverse roll coating method, a dip coating method, a curtain roll coating method, a spray coating method, a rod coating method, a brush coating method and the like are used. However, any method may be used as long as the coating liquid can be applied to the end surface substantially. After coating, if necessary, the solvent contained in the coating liquid can be dried by air drying, drying under reduced pressure, heating or the like before use. Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples.

[0010]

Example 1 and Comparative Example 1 100 parts by weight of polyvinyl chloride resin {Nipolite SE manufactured by Chisso Corporation}, 10 parts by weight of conductive carbon black, organotin stabilizer {Adeka Stub 465E manufactured by Asahi Denka Co., Ltd.} 3 parts by weight, 1.5 parts by weight of a wax-based lubricant {Wax OP manufactured by Hoechst Co., Ltd.} and 5 parts by weight of a butadiene / styrene copolymer resin-based reinforcing agent {metaprene C303 manufactured by Mitsubishi Rayon Co., Ltd.} After kneading at a temperature of 190 ° C. for 5 minutes with an 8-inch two-roll, a sheet having a thickness of 0.2 mm was prepared. This sheet is cut using a slitter, width 30 mm, length 50
cm tape was made. This tape was wound up to form a cylinder having cut surfaces on both sides. Tetrahydrofuran, which is an organic solvent, was applied to the cut surface with a brush and then air-dried at room temperature for 1 hour. When this treated cross section was observed with a scanning electron microscope, the edge was a smooth surface with a rounded edge. When the Xerox copy paper spread on a horizontal surface was lightly rubbed with the treated surface of the cylinder facing downward, no detachment was observed on the copy paper surface. As a comparative example, when the untreated surface of the cut surface was similarly rubbed against the copy paper, the surface of the copy paper became black with detached matter.

[0011]

Example 2 An untreated surface of a cylinder produced in the same manner as in Example 1 was coated with an acrylic resin (50% by weight of methyl methacrylate, 35% by weight of butyl methacrylate and 2% of methacrylic acid).
-Terpolymer containing 15% by weight of hydroxyethyl and having a weight average molecular weight of 80,000, 20% by weight, 50% by weight of ethyl acetate and 30% by weight of isopropyl alcohol
The coating liquid consisting of was applied with a brush, and then dried in an oven kept at 50 ° C. for 1 hour. When the Xerox copy paper spread on a horizontal surface was lightly rubbed with the treated surface of the cylinder facing downward, no detachment was observed on the copy paper surface.

[0012]

[Comparative Example 2] An untreated surface of a cylinder produced by the same method as in Example 1 was immersed in water, gently shaken several times for washing, and then dried in an oven kept at 50 ° C for 3 hours. . When the surface to be washed was faced down and lightly rubbed against the copy paper, the surface of the copy paper became black with detached substances.

EFFECTS OF THE INVENTION By treating the end surface of a conductive molded article by the method of the present invention, it is possible to prevent the conductive material from being detached from the end surface, and thus when used as a packaging material for precision electronic parts, It becomes possible to prevent the pollution, and its industrial effect is great.

Claims (4)

[Claims] 1. A chemically treated end face of a conductive molded article,
A method of preventing the loss of a conductive substance from the end surface by smoothing the surface. 2. The method according to claim 1, wherein the chemical treatment method comprises contacting the end face with a soluble organic solvent. 3. The method according to claim 1, wherein the chemically treating method comprises applying a coating liquid to the end face. 4. The method according to claim 1, wherein the electrically conductive molded article is an electrically conductive tape, film or sheet.