JP2015187223A - Vinyl chloride resin composition for wire coating and method for crosslinking the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vinyl chloride resin composition for wire coating, capable of suppressing discoloration even by crosslinking treatment by electron beam irradiation, and a method for crosslinking the vinyl chloride resin composition for wire coating by electron beam irradiation.SOLUTION: The vinyl chloride resin composition for wire coating includes an acetylacetone zinc of 0.01-1.0 pt.wt. to a vinyl chloride resin of 100 pts.wt. as a discoloration inhibitor and is crosslinked by electron beam irradiation. The method for crosslinking the vinyl chloride resin composition for wire coating includes irradiating the vinyl chloride resin composition for wire coating including an acetylacetone zinc of 0.01-1.0 pt.wt. to the vinyl chloride resin of 100 pts.wt. as a discoloration inhibitor with an electron beam.

Description

  The present invention relates to a vinyl chloride resin composition for covering electric wires and a method for crosslinking the same. More specifically, the present invention relates to a vinyl chloride resin composition for electric wire coating in which discoloration is suppressed even by crosslinking by electron beam irradiation, and a vinyl chloride resin composition for electric wire coating even by such crosslinking by electron beam irradiation. The present invention relates to a cross-linking method in which discoloration of a vinyl coating of an electric wire is suppressed.

  Vinyl chloride-based resin compositions have excellent electrical characteristics such as electrical insulation, arc resistance, and voltage resistance in addition to flexibility, and have been widely used as wire coating materials. Thus, an electric wire coated with a vinyl chloride resin composition, that is, a vinyl-coated electric wire is usually coated on the surface of a conductor such as a copper wire in a molten state by, for example, an extrusion method. Manufactured.

As the above-described vinyl chloride resin composition for covering electric wires, for example, a proposal has been conventionally made using, for example, hydrotalcite and organic acid zinc as a stabilizer and dialkyl terephthalate as a plasticizer. (See Patent Document 1).
Such vinyl-coated electric wires are currently used in various applications, and are evaluated by residual strength evaluated by elongation remaining after heat aging, insulation evaluated by volume resistivity, and congo red test. High quality is required for heat resistance. In particular, in automobiles, PCs, household electric appliances, etc., the covered electric wires are easily exposed to high temperatures during use. Therefore, in order to prevent deformation and deterioration, the above-mentioned covered electric wires are usually further irradiated with an electron beam. Many of the coatings are subjected to a crosslinking treatment.

  However, conventionally known vinyl chloride resin compositions for electric wire coating are subjected to crosslinking treatment by electron beam irradiation, the resin composition, that is, the electric wire coating is deteriorated and discolored, and the commercial value of the product is increased. There was a problem of significant reduction. Therefore, there has been a demand for a vinyl chloride-based resin composition for covering electric wires that can suppress discoloration even when a crosslinking treatment is performed by electron beam irradiation.

JP 2011-190320 A

  The present inventors have intensively studied to obtain the above-mentioned problem caused by crosslinking of the vinyl chloride resin composition for electric wire coating by electron beam irradiation, that is, a vinyl chloride resin composition in which discoloration of the electric wire coating is suppressed. As a result, it was found that by adding acetylacetone zinc to the vinyl chloride resin composition, discoloration of the vinyl chloride resin composition can be specifically suppressed in the crosslinking treatment by electron beam irradiation, leading to the present invention. It is a thing.

  Accordingly, an object of the present invention is to provide a vinyl chloride resin composition for wire coating in which discoloration is suppressed even by a crosslinking treatment by electron beam irradiation.

  Furthermore, this invention relates to the bridge | crosslinking method by electron beam irradiation of such a vinyl chloride resin composition for electric wire coating | cover.

  According to the present invention, a vinyl chloride resin for electric wire coating which is crosslinked by electron beam irradiation, containing 0.01 to 1.0 part by weight of acetylacetone zinc with respect to 100 parts by weight of vinyl chloride resin. A composition is provided.

  According to the present invention, the vinyl chloride resin composition for covering an electric wire preferably further contains 0.01 to 2.0 parts by weight of an organic acid zinc with respect to 100 parts by weight of the vinyl chloride resin.

  According to the present invention, the vinyl chloride resin composition for covering wires preferably further contains 0.1 to 10 parts by weight of hydrotalcite with respect to 100 parts by weight of the vinyl chloride resin.

  Further, according to the present invention, the vinyl chloride resin composition for wire coating containing 0.01 to 1.0 part by weight of acetylacetone zinc is irradiated with an electron beam with respect to 100 parts by weight of the vinyl chloride resin. A method for crosslinking a vinyl chloride resin composition for covering electric wires is provided.

  The vinyl chloride resin composition for electric wire coating according to the present invention contains acetylacetone zinc as a discoloration inhibitor, and the discoloration is remarkably suppressed in the crosslinking treatment by electron beam irradiation.

  That is, according to the method of the present invention, by adding acetylacetone zinc as a discoloration inhibitor to the vinyl chloride resin composition for wire coating, even if it is subjected to a crosslinking treatment by electron beam irradiation, the residual strength, insulation properties Thus, discoloration can be suppressed without deteriorating physical properties such as heat resistance.

  The vinyl chloride resin composition for electric wire coating that is crosslinked by electron beam irradiation according to the present invention contains 0.01 to 1.0 part by weight of acetylacetone zinc with respect to 100 parts by weight of the vinyl chloride resin.

  According to the present invention, the vinyl chloride resin, which is a resin component of the vinyl chloride resin composition for wire coating, includes not only a vinyl chloride homopolymer but also a copolymer of vinyl chloride and various copolymerizable monomers. Including polymers. Examples of such copolymers include vinyl chloride-vinyl acetate copolymer, vinyl chloride-ethylene-vinyl acetate copolymer, vinyl chloride-ethylene copolymer, vinyl chloride-propylene copolymer, vinyl chloride- Styrene copolymer, vinyl chloride-isobutylene copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-urethane copolymer, vinyl chloride-acrylic acid ester copolymer, vinyl chloride-styrene-maleic anhydride copolymer Polymer, vinyl chloride-styrene-acrylonitrile copolymer, vinyl chloride-butadiene copolymer, vinyl chloride-isoprene copolymer, vinyl chloride-chlorinated propylene copolymer, vinyl chloride-vinylidene chloride-vinyl acetate copolymer, Vinyl chloride-maleic acid ester copolymer, vinyl chloride-methacrylic acid ester copolymer Vinyl chloride - acrylonitrile copolymer, vinyl chloride - can be exemplified maleimide copolymer. The method for producing these vinyl chloride resins may be any of emulsion polymerization, suspension polymerization, solution polymerization, bulk polymerization and the like, and is not limited by the polymerization method.

  The vinyl chloride resin composition for electric wire coating according to the present invention contains 0.01 to 1.0 part by weight of 100 parts by weight of vinyl chloride resin with zinc acetylacetone as a discoloration inhibitor. According to this invention, the said discoloration inhibitor has an effect which suppresses the discoloration by bridge | crosslinking using the electron beam irradiation of the vinyl chloride resin composition for electric wire coating | coated which mix | blended this specifically.

  In the vinyl chloride resin composition for wire coating, when the proportion of the discoloration inhibitor is less than 0.01 parts by weight with respect to 100 parts by weight of the vinyl chloride resin, the resulting vinyl chloride resin composition for wire coating is obtained. It is difficult to suppress discoloration in crosslinking by electron beam irradiation. However, when the proportion of the color change inhibitor is more than 1.0 parts by weight with respect to 100 parts by weight of the vinyl chloride resin, the resulting vinyl chloride resin composition for coating an electric wire is discolored upon crosslinking by electron beam irradiation. Is suppressed, but on the other hand, the heat resistance is inferior and zinc may be eluted.

  In this invention, it is preferable that the vinyl chloride resin composition for electric wire coating | cover contains the said discoloration inhibitor in 0.03-0.8 weight part with respect to 100 weight part of vinyl chloride resin.

  The vinyl chloride resin composition for electric wire coating according to the present invention preferably contains 0.01 to 2.0 parts by weight of organic acid zinc with respect to 100 parts by weight of vinyl chloride resin, more preferably, In the range of 0.1 to 1.0 parts by weight.

  According to the present invention, the organic acid zinc cooperates with the discoloration inhibitor and has the effect of suppressing the discoloration for a long time after the crosslinking treatment by electron beam irradiation of the vinyl chloride resin composition for wire coating. Have.

  When the proportion of the organic acid zinc is less than 0.01 parts by weight with respect to 100 parts by weight of the vinyl chloride resin in the vinyl chloride resin composition for wire coating, in cooperation with the discoloration inhibitor, The effect of suppressing discoloration due to the crosslinking treatment by electron beam irradiation of the vinyl chloride resin composition is poor. However, when the proportion of the organic acid zinc is more than 2.0 parts by weight with respect to 100 parts by weight of the vinyl chloride resin, the resulting vinyl chloride resin composition for wire coating is inferior in heat resistance, There is a risk of elution. Furthermore, problems such as poor appearance occur during molding.

  The organic acid in the organic acid zinc is not particularly limited as long as it is conventionally used in the vinyl chloride resin composition itself or as a metal salt. For example, acetic acid, Propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, 2-ethylhexylic acid, neodecanoic acid, capric acid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid, isostearic acid, stearin Acid, 12-hydroxystearic acid, behenic acid, montanic acid, benzoic acid, monochlorobenzoic acid, pt-butylbenzoic acid, dimethylhydroxybenzoic acid, 3,5-di-t-butyl-4-hydroxybenzoic acid, Toluic acid, dimethylbenzoic acid, ethylbenzoic acid, cumic acid, n-propylbenzoic acid, Nobenzoic acid, N, N-dimethylaminobenzoic acid, acetoxybenzoic acid, salicylic acid, pt-octylsalicylic acid, elaidic acid, oleic acid, linoleic acid, linolenic acid, thioglycolic acid, mercaptopropionic acid, octylmercaptopropionic acid Monovalent organic carboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid, hydroxyphthalic acid, chlorophthalic acid , Divalent organic carboxylic acids such as aminophthalic acid, maleic acid, fumaric acid, citraconic acid, metaconic acid, itaconic acid, aconitic acid, thiodipropionic acid, monoesters or monoamide compounds of these divalent organic carboxylic acids, butanetricarboxylic acid , Butanetetracarbo Acid, hemimellitic acid, and trimellitic acid, mellophanic acid, the di- or triesters of tri- or tetravalent organic carboxylic acids such as pyromellitic acid.

  Among these, higher fatty acids having 12 to 20 carbon atoms such as myristic acid, palmitic acid, isostearic acid, stearic acid and the like are preferable. Therefore, for example, zinc palmitate and zinc stearate are preferably used.

  The vinyl chloride resin composition for wire coating according to the present invention has a hydrotalcite content of 0.1 to 10 per 100 parts by weight of vinyl chloride resin so that the resulting vinyl chloride resin composition has heat resistance. It is preferable to contain in the range of a weight part, and it is more preferable to contain in the range of 0.3-10 weight part. In particular, it is preferable that the obtained resin composition contains hydrotalcite in a range of 2 to 10 parts by weight in view of the heat resistance that is practically required, especially the colorability after heating and the residual elongation rate. .

Hydrotalcite has the general formula (1)
[(Mg) _x (Zn) _y ] _1-z (Al) _z (OH) ₂ (CO ₃ ) _{z / 2} · mH ₂ O (1)
(X, y, z and m are numbers satisfying 0.5 ≦ x ≦ 1, 0 ≦ y ≦ 0.5, x + y = 1, 0.1 ≦ z ≦ 0.5 and 0 ≦ m <1, respectively. .)
It is 1 type of the layered double hydroxide represented by these.

  In the hydrotalcite represented by the general formula (1), when y is 0, it is called Mg / Al hydrotalcite, and when y is not 0 and contains zinc, zinc-modified hydrotalcite It is called a site.

  In the present invention, both Mg / Al hydrotalcite and zinc-modified hydrotalcite can be used. However, zinc-modified hydrotalcite increases the amount of zinc in the vinyl chloride resin composition compared to Mg / Al hydrotalcite when the same amount is added to the vinyl chloride resin composition. Since there is a tendency to deteriorate the resin and the residual elongation rate, the Mg / Al system is more preferably used.

  The vinyl chloride resin composition for electron beam coating according to the present invention preferably contains a β-diketone, particularly for improving the initial colorability.

  Examples of the β-diketone include stearoylacetylmethane, benzoylacetylmethane, dibenzoylmethane, octylbenzoylmethane, bis (4-octylbenzoyl) methane, 4-methoxybenzoylbenzoylmethane, and bis (4-carboxymethylbenzoyl) methane. Preferred examples include alkanoylaroylmethane and diaroylmethane such as 2-carboxymethylbenzoylacetyloctylmethane and 2-benzoylcyclohexane.

  According to the present invention, in the vinyl chloride resin composition for electron beam coating, such a β-diketone is preferably in the range of 5 wt% or less, more preferably, with respect to 100 parts by mass of the vinyl chloride resin. In the range of 0.1 to 1.0 parts by weight.

  The vinyl chloride resin composition for electric wire coating according to the present invention contains, as a plasticizer, an organic carboxylic acid alkyl ester in a range of usually 1 to 100 parts by weight with respect to 100 parts by weight of the vinyl chloride resin, In the range of 5 to 50 parts by weight.

  As the above-mentioned organic carboxylic acid alkyl ester, conventionally known ones are appropriately used. Specific examples include, for example, di-n-butyl phthalate, di-n-octyl phthalate, di-2 phthalate. -Ethylhexyl (DEHP), diisooctyl phthalate, dioctyl decyl phthalate, diisodecyl phthalate, butyl benzyl phthalate, di-2-ethylhexyl isophthalate, etc., di-2-ethylhexyl adipate, di-n adipate -Fatty acid esters such as decyl, di-2-ethylhexyl adipate, dibutyl sebacate, di-2-ethylhexyl sebacate, trimellitic acid ester, pyromellitic acid ester and the like.

  In the present invention, among the above-mentioned organic carboxylic acid alkyl esters, tri-2-ethylhexyl trimellitic acid (TOTM) is particularly preferably used because the residual elongation after heat aging can be maintained.

  In addition to the above, as organic carboxylic acid ester plasticizers, for example, citric acid esters such as trihexyl acetyl citrate and trihexyl n-butyl citrate, glycolic acid esters, diisononylcyclohexane dicarboxylate, di-2-ethylhexyl cyclohexane Examples include cyclohexane dicarboxylate such as dicarboxylate.

  In the present invention, in addition to the above organic carboxylic acid ester plasticizer, for example, tributyl phosphate, tri-2-ethylhexyl phosphate, tri-2-ethylhexyl diphenyl phosphate, tricresyl phosphate, etc. Alkyl sulfonic acid derivatives such as sulfonic acid phenyl ester and n-butylbenzenesulfonamide are also preferably used.

  Moreover, in this invention, not only as a plasticizer but in order to provide heat resistance to the obtained vinyl chloride resin composition, an epoxy compound is also mix | blended with a vinyl chloride resin composition as needed.

  Examples of such epoxy compounds include bisphenol-type and novolak-type epoxy resins, epoxidized soybean oil, epoxidized linseed oil, epoxidized castor oil, epoxidized tung oil, epoxidized fish oil, epoxidized beef tallow oil, and epoxidized safflower oil. , Epoxidized tall oil fatty acid octyl, epoxidized linseed oil fatty acid butyl, epoxy methyl stearate, epoxy butyl stearate, 2-ethylhexyl epoxy stearate, stearyl epoxy stearate, tris (epoxypropyl) isocyanurate, 3- (2- Xenoxy) -1,2-epoxypropane, epoxidized polybutadiene, bisphenol-A diglycidyl ether, vinylcyclohexene diepoxide, dicyclopentadiene diepoxide, 3,4-epoxycyclo Hexyl-6-methyl-epoxycyclohexane carboxylate, bis (3,4-epoxycyclohexyl) adipate, and the like.

  Among the above, epoxidized vegetable oils such as epoxidized soybean oil, epoxidized linseed oil, and epoxidized castor oil are preferably used.

  The vinyl chloride resin composition for electric wire coating according to the present invention may contain, as necessary, an epoxy compound as described above in an amount of 30 parts by weight or less, preferably 1 to 100 parts by weight of the vinyl chloride resin. In the range of 10 parts by weight.

  The vinyl chloride resin composition for electric wire coating according to the present invention can contain various additives that are conventionally known to be usable for an electric wire coating resin composition as required. Examples of such additives include lubricants, neutralizers, colorants, ultraviolet absorbers, antioxidants and the like.

  For example, examples of the lubricant include stearic acid and palmitic acid, and examples of the neutralizing agent include zinc oxide, zinc carbonate, calcium carbonate, magnesium carbonate, talc, and barium sulfate. Can do.

  In addition, the vinyl chloride resin composition for covering electric wires according to the present invention can use trimethylolpropane trimethacrylate, dipentaerythritol hexaacrylate, or the like as a crosslinking aid.

  As described above, the vinyl chloride resin composition for electric wire coating according to the present invention contains acetylacetone zinc as a discoloration inhibitor, and due to its specific effect, discoloration is suppressed even by a crosslinking treatment by electron beam irradiation. The However, instead of acetylacetone zinc, acetylacetone, or β-diketone zinc other than acetylacetone zinc, for example, stearoylbenzoylmethane zinc, and acetylacetone metal salts other than zinc salt, such as calcium salt and magnesium salt However, it does not have the effect of suppressing discoloration of the vinyl chloride resin composition due to the crosslinking treatment by electron beam irradiation.

  The vinyl chloride resin composition for covering electric wires according to the present invention can be produced by a conventionally known method. For example, the various components described above are mixed at a predetermined ratio using a Henschel mixer, a super mixer, etc., and the resulting mixture is uniformly kneaded using a roll, a Banbury mixer, an extruder, etc. The resin composition can be obtained.

  In order to crosslink the vinyl chloride resin composition for electric wire coating according to the present invention, as described above, after a conductor such as a copper wire is coated with the resin composition, an already well-known means is used. What is necessary is just to irradiate an electron beam to the said vinyl chloride resin composition for electric wire coating | covers which is electric wire coating | cover, and, thereby, the covered electric wire by which discoloration was suppressed can be obtained.

  The dose for the crosslinking treatment by electron beam irradiation of the vinyl chloride resin composition is usually about 20 to 60 kGy, but is not limited thereto.

  Hereinafter, the present invention will be described with reference to examples and comparative examples, but the present invention is not limited to these examples.

  Details of various components used in the following Examples and Comparative Examples are shown below.

Vinyl chloride resin Shin-Etsu Chemical Co., Ltd. TK-1000 (average polymerization degree 1000)
TOTM
TOPLUS made by J Plus Co., Ltd.
Epoxidized soybean oil ADEKA O-130P
Zinc stearate SZ-2000 manufactured by Sakai Chemical Industry Co., Ltd.
Acetylacetone zinc Reagent stearoyl benzoylmethane Rhodia stub 50 manufactured by Tokyo Chemical Industry Co., Ltd.
Acetylacetone acetylacetone calcium, manufactured by Tokyo Chemical Industry Co., Ltd. Rhodia stub 77 manufactured by Rhodia
Magnesium Acetylacetone Chemical Industry Co., Ltd. Synthetic Stearoylbenzoylmethane Zinc Chemical Industry Co., Ltd. Synthetic Product Mg / Al Hydrotalcite Chemical Industry Co., Ltd. STBIACE HT-1 ([Mg _0.66 Al _0.33 (OH) ₂ ] [(CO ₃ ) _0.16 · 0.5H ₂ O]).
Zinc-modified hydrotalcite STABIACE HT-7 ([Mg _0.86 Zn _0.12 ] _0.67 Al _0.33 (OH) ₂ (CO ₃ ) _0.16 · 0.5H ₂ O) manufactured by Sakai Chemical Industry Co., Ltd.

Examples 1-14 and Comparative Examples 1-5
After mixing each component with the composition shown in Table 1 and Table 2, it was kneaded for 5 minutes at a temperature of 170 ° C. using an 8-inch roll to obtain a 0.3 mm thick sheet.

  Each obtained sheet was subjected to the following test, and the degree of discoloration was visually observed and evaluated. The results are shown in Tables 1 and 2.

(1) Initial colorability of press The sheet was preheated at 170 ° C. for 5 minutes using an electric press and then pressed at a pressure of 50 kgf / cm ² for 5 minutes, and the degree of discoloration of the sheet thus obtained was evaluated.

(2) Static oven heat resistance The sheet was cut into a 3 cm × 4 cm square and aged in a gear oven at 180 ° C. for 120 minutes to evaluate the degree of discoloration.

(3) Discoloration 24 hours after electron beam crosslinking (room temperature) The sheet was subjected to crosslinking treatment by electron beam irradiation at an acceleration voltage of 4.8 MeV and an irradiation intensity of 60 kGy, and then the sheet was left to stand at room temperature for 24 hours. The degree of discoloration was evaluated.

(4) Discoloration after 168 hours (room temperature) after electron beam crosslinking The sheet was subjected to crosslinking treatment by electron beam irradiation at an acceleration voltage of 4.8 MeV and an irradiation intensity of 60 kGy, and then the sheet was left to stand at room temperature for 168 hours. The degree of discoloration was evaluated.

(5) Discoloration after electron beam crosslinking and standing at 50 ° C. for 168 hours The sheet was subjected to crosslinking treatment by electron beam irradiation at an acceleration voltage of 4.8 MeV and an irradiation intensity of 60 kGy, and then in a constant temperature oven at 50 ° C. 168 The degree of discoloration of the sheet when left for a period of time was evaluated.

(6) Residual elongation after heat aging The sheet was preheated at 170 ° C. for 5 minutes using an electric press and then pressed at a pressure of 50 kgf / cm ² for 5 minutes to produce a sheet having a thickness of 1 mm. Crosslinking was performed by irradiation with an electron beam at a voltage of 4.8 MeV and an irradiation intensity of 60 kGy. The sheet thus obtained was cut in accordance with JIS-K6723 to obtain a dumbbell, which was heat-aged at 158 ° C. for 168 hours, and then the elongation E was measured with a tensile tester. Further, the elongation ratio E ₀ of the dumbbell before heat aging was measured, and the residual elongation ratio after heat aging at 158 ° C. for 168 hours was determined from the following formula.

Residual elongation rate = (E / E ₀ ) × 100 (%)

(7) Thermal stability In the Congo Red test based on JIS-K6723, the hydrochloric acid generation time at 180 ° C., that is, the time until the vinyl chloride resin composition was decomposed to generate hydrochloric acid was measured.

(8) Volume resistivity After preheating the sheet at 170 ° C. for 5 minutes using an electric press, the sheet was pressed at a pressure of 50 kgf / cm ² for 5 minutes to produce a sheet having a thickness of 1 mm. The sheet thus obtained was measured according to JIS-K6723.

  The evaluation criteria for the degree of discoloration of the sheet after each test are as follows. When the color change was hardly observed, ◎, when the color change was slightly observed, ◯, when the color change was observed but at an acceptable level, Δ, and when the color change was remarkable, X was given.

  As shown in Tables 1 and 2, according to the present invention, the vinyl chloride resin composition prepared by blending vinyl chloride resin with acetylacetone zinc as a discoloration inhibitor suppresses discoloration even by a crosslinking treatment by electron beam irradiation. Has been.

On the other hand, as shown in Table 2, the vinyl chloride resin compositions according to Comparative Examples 1 to 5 replaced stearoylbenzoylmethane, acetylacetone, acetylacetone calcium, acetylacetonemagnesium and stearoylbenzoylmethanezinc, respectively, instead of acetylacetonezinc. However, discoloration of the vinyl chloride resin composition due to electron beam irradiation crosslinking cannot be suppressed.

Claims (8)

  A vinyl chloride resin composition for coating an electric wire that is crosslinked by electron beam irradiation, containing 0.01 to 1.0 part by weight of acetylacetone zinc as a discoloration inhibitor for 100 parts by weight of a vinyl chloride resin. .   The vinyl chloride resin composition for covering electric wires according to claim 1, wherein the vinyl chloride resin composition further comprises 0.01 to 2.0 parts by weight of an organic acid zinc with respect to 100 parts by weight of the vinyl chloride resin.   The vinyl chloride resin composition for electric wire coating according to claim 1, wherein the vinyl chloride resin composition further comprises 0.1 to 10 parts by weight of hydrotalcite with respect to 100 parts by weight of the vinyl chloride resin.   The vinyl chloride resin composition for electric wire coating according to claim 3, wherein the hydrotalcite is Mg / Al hydrotalcite.   An electric wire coating comprising irradiating an electron beam with a vinyl chloride resin composition for electric wire coating containing 0.01 to 1.0 part by weight of acetylacetone zinc as a discoloration inhibitor for 100 parts by weight of a vinyl chloride resin Crosslinking method for vinyl chloride resin composition for use.   The vinyl chloride resin composition for electric wire coating according to claim 5, wherein the vinyl chloride resin composition further comprises 0.01 to 2.0 parts by weight of an organic acid zinc with respect to 100 parts by weight of the vinyl chloride resin. Crosslinking method.   The method for cross-linking a vinyl chloride resin composition for covering electric wires according to claim 5, wherein the vinyl chloride resin composition further comprises 0.1 to 10 parts by weight of hydrotalcite with respect to 100 parts by weight of the vinyl chloride resin. . The method for crosslinking a vinyl chloride resin composition for covering electric wires according to claim 5, wherein the hydrotalcite is Mg / Al hydrotalcite.