JPH08241628A - Automobile electric wire coated by thermoplastic fluorine-containing resin - Google Patents

Abstract

PURPOSE: To provide an automobile electric wire having proper abrasion resistance, flexibility, and workability, and a thin thickness coating layer. CONSTITUTION: In this coating electric wire for an automobile, a coating layer is formed of a thermoplastic fluorine-contained resin composition containing the following components (a) and (b), (a): a thermoplastic fluorine-contained resin of 95-50wt.%, and (b): 'reformed-ethylen'-'vinyl-acetate' copolymer obtained by making an 'ethylene'-'vinyl-acetate' copolymer of 15-50wt.% vinyl acetate content and vinyl acetate follow a graft reaction condition, and wherein all vinyl acetate content, including vinyl acetate previously contained, is 30-70wt.%. Vinyl acetate, made into copolymer out of all the vinyl acetate content, is 5wt.% or more, and 'reformed-ethylene'-'vinyl-acetate' copolymer, wherein the melt flow rate(MFR) is 0.01-10g/10min, is 5-50wt.%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automobile electric wire having a coating layer of a specific thermoplastic fluorine-containing resin composition.

[0002]

2. Description of the Related Art Automotive electric wires are widely used in general low-voltage circuits such as in-vehicle starting circuits, charging circuits, and lighting circuits. As a coating material for these automotive electric wires, vinyl chloride resin is solvent resistant and oil resistant. It is generally used because it has many excellent properties such as resistance, water resistance, acid resistance, alkali resistance, and flame retardancy. On the other hand, with the increasing use of wiring in automobiles, the weight ratio of automobile wires / cables to the weight of automobiles has also increased, and it is required to reduce the thickness of the coating layer in order to reduce the weight. There is. However, in terms of thinning, the vinyl chloride resin is not always satisfactory in terms of abrasion resistance, and it is impossible to reduce the thickness in terms of protection characteristics. As a material having excellent wear resistance, tetrafluoroethylene, tetrafluoroethylene-propylene copolymer,
Thermoplastic fluororesins such as polyvinylidene fluoride and ethylene-tetrafluoroethylene copolymer are known, but these thermoplastic fluororesins generally have poor flexibility and molding processability, and are expensive. Automotive electric wire
It is not widely used as a cable material. Further, in order to improve the molding processability and flexibility of the thermoplastic fluororesin, it has been proposed to blend a resin in which a vinyl acetate monomer is graft-copolymerized with an ethylene-vinyl acetate copolymer into the thermoplastic fluororesin. (JP-A-60-99152).

[0003]

DISCLOSURE OF THE INVENTION According to the present invention, as a result of earnest studies for the purpose of developing an automobile electric wire capable of thinning the coating layer of the electric wire of the automobile, that is, making the automobile lighter, The present invention has been completed based on the finding that the use of the thermoplastic fluororesin composition as the coating layer satisfies the required properties and achieves thinning. That is, the present invention is a coated electric wire for an automobile, which has an extrusion coating layer of a thermoplastic fluorine-containing resin composition containing the following components (a) and (b) on a conductor. Component (a) : thermoplastic fluorine-containing resin 95 to 50% by weight Component (b) : ethylene-vinyl acetate copolymer having a vinyl acetate content of 15 to 50% by weight and a vinyl acetate obtained by subjecting it to a graft reaction condition Ethylene-vinyl acetate copolymer having a total vinyl acetate content of 30 to 70% by weight including vinyl acetate which is contained in advance, of which vinyl acetate which is graft-copolymerized is 5% by weight or more. Yes, and melt flow rate (MFR) 0.01 to 10 g /
Modified ethylene-vinyl acetate copolymer which is 10 minutes 5.
~ 50% by weight

[Detailed Description of the Invention] (1) Thermoplastic Fluorine Resin Composition The thermoplastic fluorine-containing resin as the component (a) constituting the thermoplastic fluororesin composition of the coating layer of the present invention is, for example, polyfluorinated. Vinyl, polyvinylidene fluoride, polychlorotrifluoroethylene, ethylene-tetrafluoroethylene copolymer, ethylene-chlorotrifluoroethylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-propylene copolymer Commercially available products such as tetrafluoroethylene-perfluoroalkylvinylether copolymer are appropriately used, but among them, polyvinyl fluoride, polyvinylidene fluoride and the like are preferable in terms of good moldability.

The modified ethylene-vinyl acetate copolymer as the component (b) is an ethylene-vinyl acetate copolymer having a vinyl acetate content of 15 to 50% by weight, preferably 20 to 35% by weight (hereinafter referred to as "EVA"). And a vinyl acetate monomer is subjected to a graft reaction condition, and has a MFR of 0.01 to 10 g / 10.
Minutes, preferably 0.05 to 5 g / 10 minutes, and a total vinyl acetate content of 30 to 70% by weight, preferably 35 to 50% by weight, in the form of a resin. Such a modified ethylene-vinyl acetate copolymer resin (hereinafter referred to as "modified EVA") is preferably produced by the following method.

1) Raw Materials (a) Ethylene-Vinyl Acetate Copolymer (EVA) To produce a modified EVA, unmodified EVA having a vinyl acetate content of 15 to 50% by weight is used. If the vinyl acetate content of EVA used here is less than the above amount, the properties of the obtained modified EVA will be insufficient because the amount of vinyl acetate monomer to be impregnated and polymerized will be limited. On the other hand, if the above amount is exceeded, EVA will be insufficient. Since the softening point is low, the particles are melted and fused during the polymerization and agglomerated, which is not preferable. This EVA has an MFR of generally 5 to 400 g / 10 minutes, especially 10 to 20
0 g / 10 min is preferred. Also, the amount of vinyl acetate monomer used is determined based on the amount of total vinyl acetate to be contained in the finally produced modified EVA. Modified E
When the content of total vinyl acetate contained in VA is less than the above amount, the compatibility with the thermoplastic fluorine-containing resin is insufficient, and it is difficult to achieve the intended purpose. Further, if the total vinyl acetate content exceeds the above-mentioned amount, the moldability becomes poor.

(B) Vinyl acetate monomer As the vinyl acetate monomer used for producing the modified EVA, a commercially available product can be used. It is also possible to use a mixture of a majority of the vinyl acetate monomer with another vinyl monomer copolymerizable therewith. Here, other vinyl monomers include vinyl esters such as vinyl propionate and vinyl persaticate; acrylic acid, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methacrylic acid, methyl methacrylate. , Butyl methacrylate, maleic anhydride, dimethyl maleate,
Unsaturated organic acids such as maleic acid di (2-ethylhexyl) or derivatives thereof; unsaturated aromatic monomers such as styrene and 2,5-dichlorostyrene; unsaturated nitriles such as acrylonitrile and methacrylonitrile; vinyl chloride , Unsaturated mono- or dihalides such as vinylidene chloride.

The vinyl acetate monomer is usually 10 to 50 parts by weight based on 100 parts by weight of the ethylene-vinyl acetate copolymer.
Parts by weight, preferably 15-30 parts by weight, are added. The addition can be done all at once or in portions. In subjecting EVA and vinyl acetate monomer as described above to the graft reaction conditions, a radical generator is usually used except for the reaction by radiation.

(C) Radical generator As a radical generator, a general-purpose one can be used, but in view of the preferred graft reaction method described later, the decomposition temperature is 50 ° C. or higher and it is oil-soluble. Those are preferable. Here, the "decomposition temperature" means a temperature at which 0.1 mol of a radical generator is added to 1 liter of benzene.
Decomposition rate of radical generator is 50% when left for 0 hours
Is the temperature. The so-called "decomposition temperature for obtaining a half-life of 10 hours" is meant. If a polymer having a low decomposition temperature is used, the polymerization of the vinyl acetate monomer may proceed abnormally, and there is a drawback that a homogeneous modified polymer cannot be obtained. However, it is also possible to perform a graft reaction efficiently by performing a stepwise or continuous decomposition by appropriately combining those having a high decomposition temperature and those having a low decomposition temperature.

Examples of such a radical generator include 2,4-dichlorobenzoylperoxide, t-butylperoxypivalate, o-methylbenzoylperoxide, bis-3,5,5-trimethylhexanoyl. Peroxide, octanoylperoxide, benzoylperoxide, t-butylperoxy-2-ethylhexanoate, cyclohexanoneperoxide,
2,5-Dimethyl-2,5-dibenzoylper-oxyhexane, t-butylper-oxybenzoate, di-t-
Organic peroxides such as butyl-dipa-oxyphthalate, methylethylketone peroxide, dicumylperoxide, di-t-butylperoxide; azobisisobutyronitrile, azobis (2,4-dimethylvaleronitrile), etc. There are azo compounds and the like.

The amount of the radical generator used is in the range of about 0.01 to 10% by weight with respect to the amount of the vinyl acetate monomer used, and is appropriately adjusted depending on the type of radical generator and reaction conditions. If the amount used is less than this amount, the reaction does not proceed smoothly. On the other hand, if the amount used exceeds this amount, gel is likely to be formed in the modified EVA, and the effect of the present invention is difficult to be exhibited.

2) Manufacture of modified EVA Modified EV by subjecting each of these raw material components to a graft polymerization reaction.
A is produced, and production by the aqueous suspension grafting method described below is a particularly preferable method in that it is easy to control the gel content. That is,
An aqueous suspension containing EVA particles having a vinyl acetate content of 15 to 50% by weight, a vinyl acetate monomer and a radical generator,
The temperature is raised to a temperature at which decomposition of the initiator does not substantially occur,
After the monomer is impregnated into the EVA particles such that the amount of the unimpregnated free monomer is less than 20% by weight, the aqueous suspension is further heated to complete the polymerization of the monomer. The method is preferred and will be described.

Impregnation of EVA Particles with Vinyl Acetate A typical method of impregnating EVA particles with vinyl acetate monomer in an aqueous medium is to use an aqueous suspension of EVA particles, preferably a radical generator (and optionally other Vinyl acetate monomer in which the additive) is dissolved and stirred, or EVA particles are added to an aqueous dispersion of a vinyl acetate monomer in which a radical generator is dissolved and the mixture is stirred. In the impregnation step, industrially, the temperature should be raised to a temperature at which the radical generator is not substantially decomposed to efficiently perform impregnation, and it is generally preferable to operate at room temperature to 100 ° C. Since EVA is relatively compatible with vinyl acetate monomer, 20
The vinyl acetate polymer particles obtained by polymerizing only the free vinyl acetate monomer are independent of the modified EVA particles because the EVA particles are impregnated during the polymerization even if less than wt% of the vinyl acetate monomer is released. And does not precipitate. The impregnation time is usually about 2 to 8 hours.

The amount of the modified EVA particles and vinyl acetate monomer in the aqueous suspension used with respect to water is usually about 5 to 100 parts by weight per 100 parts by weight of water.
Such an aqueous suspension can be maintained in a stable suspended state by simply performing sufficient stirring, but the suspension can be prepared more easily and stably by using an appropriate suspension stabilizer. be able to. Specific examples of the suspension stabilizer in this case include polyvinyl alcohol and methyl cellulose.
, Water-soluble polymer substances such as hydroxycellulose, anionic surfactants such as alkylbenzene sulfonate, nonionic surfactants such as polyoxyethylene alkyl ether, or magnesium oxide, A water-insoluble inorganic salt such as calcium phosphate or the like is used alone or in a mixture in an amount of about 0.01 to 10% by weight with respect to water. When the EVA particles are impregnated with vinyl acetate monomer (and a radical generator, etc.), auxiliary materials such as a plasticizer, a lubricant and an antioxidant can be simultaneously impregnated (these auxiliary materials have already been added to EVA). Sometimes,
It can also be added after the graft polymerization reaction).

Polymerization When the temperature of the aqueous suspension thus prepared is raised to a temperature above the temperature at which the used radical generator decomposes at an appropriate rate, the impregnated vinyl acetate monomer will polymerize. Modified EVA particles are produced. It is preferable to appropriately stir the aqueous suspension during the polymerization. The polymerization temperature is generally 50-
It should be appropriately selected within the range of 100 ° C., but it does not have to be constant throughout the polymerization process. If the polymerization temperature exceeds 100 ° C., not only gelation is likely to occur, but also agitation tends to cause splitting of particles and formation of sticky lumps of particles.

The polymerization time is usually about 2 to 10 hours. After the polymerization, a modified EVA particle in which the shape of the EVA particle used is almost kept as it is can be obtained by carrying out the same treatment as an ordinary aqueous suspension polymerization aftertreatment of a vinyl monomer (for example, styrene). Therefore, EVA used before reforming
The powder may be in the form of powder, but it is convenient to use the form of particles in consideration of handling during the subsequent molding process. That is, the particle size is preferably one that is usually used as a molding material, because the modified EVA produced can be directly used as a molding material, and generally, the average particle diameter is 1 to 8 mm,
It is preferably about 3 to 7 mm. No significant change is observed in the dimensions before and after the modification treatment. Obtained modified EVA
Is a graft copolymerized 5% by weight or more, preferably 7% by weight or more, of all the introduced vinyl acetate monomers. Such modified EVA has an MFR of 0.01-
This MFR is in the range of 10g / 10min.
However, if it is less than the above range, it is difficult to reduce the thickness of the coating layer. On the other hand, if it exceeds the above range, the extrusion moldability becomes poor, which is not preferable.

The blending ratio of the components (a) and (b) as described above is 95 to 50% by weight, preferably 90 to 60% by weight, of (a) the thermoplastic fluorine-containing resin, and (b) modified E.
VA is 5 to 50% by weight, preferably 10 to 40% by weight. If the component (a) exceeds the above range, flexibility is insufficient, and if it is less than the above range, abrasion resistance and heat resistance are not satisfactory. In addition, in the modified EVA,
Other polymers, inorganic fillers, stabilizers, flame retardants, colorants and the like can be mixed and used as long as the effects of the present invention are not impaired.

[0018]

EXAMPLES Next, the present invention will be described more specifically by way of examples. Reference Example 1 of manufacturing process of modified EVA A pure water of 20 kg, a suspension of tricalcium phosphate of 0.6 kg, and sodium dodecylbenzenesulfonate of 0.6 g were mixed in an autoclave of 50 liters to prepare an aqueous medium. , EVA particles with a particle size of 3 to 4 mm (MFR30
g / 10 minutes, vinyl acetate content 33% by weight) 7 kg,
Stir to suspend. Separately, 64.5 g of t-butylperoxypivalate and 3.6 g of benzoylperoxide were dissolved in 3 kg of vinyl acetate, and this was added to the above suspension system,
Nitrogen was introduced into the autoclave and the inside of the system was pressurized to 0.5 Kg / cm 2. Furthermore, the temperature inside the autoclave was raised to 50 ° C,
The whole EVA particles were impregnated with vinyl acetate containing a polymerization initiator and the like while being left stirring for 3 hours at this temperature. Next, this suspension was heated to 63 ° C., polymerization was carried out by allowing the suspension to stir at this temperature for 8 hours to carry out polymerization, and further to 90 ° C. and 2
The time was maintained to complete the polymerization. After cooling, the solid content was taken out and washed with water to obtain 10 kg of modified EVA-1 particles. The modified EVA-1 thus obtained had an MFR of 0.1 g / 10 minutes and a total vinyl acetate content of 53% by weight. In addition, the graft copolymerized vinyl acetate monomer was 10% by weight.

Reference Example 2 10 kg of modified EVA-2 particles was obtained in the same manner as in Reference Example 1, except that the temperature was raised to 80 ° C. instead of 90 ° C. and maintained for 2 hours to complete the polymerization. It was Obtained modified E
MFR of VA is 1g / 10 minutes, total vinyl acetate content is 53
% By weight. In addition, the graft copolymerized vinyl acetate monomer was 10% by weight.

Examples 1 to 8 and Comparative Examples 1 to 3 A resin composition having the composition shown in Table 1 was prepared and a 30 mm extruder (L / D = 25) was used to prepare a copper wire having an outer diameter of 0.9 mm. The (stranded wire) was extrusion-coated to a thickness of 0.2 mm to prepare an insulated electric wire. The evaluation results for the insulated wire created here are shown in the table.
1 is as shown in the lower column.

The evaluation test of flame retardancy, flexibility and abrasion resistance of the obtained electric wire was carried out according to the following criteria or method. Flame retardance: JIS C3005 horizontal test After burning an insulated electric wire held horizontally by a burner, removing the burner and extinguishing the flame within 30 seconds is a pass,
Those that burn for 30 seconds or more are rejected. Flexibility: The amount of deflection f in FIG. 1 is measured. Abrasion: By scrape test (see FIG. 2). The number of blade reciprocations (60 reciprocations / minute) until electrical conduction between the conductor and the blade due to wear of the insulator is measured.

[0022]

[Table 1]

[Brief description of drawings]

FIG. 1 is a schematic diagram for explaining a method of evaluating flexibility of a covered electric wire.

FIG. 2 is a schematic diagram for explaining a method of evaluating the wear resistance of a covered electric wire.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tetsuro Katayama 2-5-2 Marunouchi, Chiyoda-ku, Tokyo Sanryo Chemical Co., Ltd. Functional Chemicals Company

Claims (1)

[Claims] 1. A coated electric wire for an automobile, comprising an extruded coating layer of a thermoplastic fluorine-containing resin composition containing the following components (a) and (b) on a conductor. Component (a) : thermoplastic fluorine-containing resin 95 to 50% by weight Component (b) : ethylene-vinyl acetate copolymer having a vinyl acetate content of 15 to 50% by weight and a vinyl acetate obtained by subjecting it to a graft reaction condition Ethylene-vinyl acetate copolymer having a total vinyl acetate content of 30 to 70% by weight including vinyl acetate which is contained in advance, of which vinyl acetate which is graft-copolymerized is 5% by weight or more. Yes, and melt flow rate (MFR) 0.01 to 10 g /
Modified ethylene-vinyl acetate copolymer which is 10 minutes 5.
~ 50% by weight