JPH11203941A - Manufacture of foaming vinyl sheath wire/cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the bubble fraction of a sheath layer and provide excellent insulation performance with a satisfactory state of insulation-resistance foaming cells, by applying to a sheath an ethylene-vinyl acetate copolymer mixed with azodicarbonamide as foaming agent. SOLUTION: Azodicarbonamide as foaming agent is mixed, as master batch having an ethylene-vinyl acetate copolymer as base resin, into a vinyl chloride resin composition. One to 50% of the master batch is suitable as the mixing rate of the azodicarbonamide. The mixing rate of the azodicarboxylic acid amide relative to the soft vinyl chloride resin composition can be adjusted according to the bubble fraction of a sheath and suitably is 0.001 to 0.5%. Because the azodicarboxylic acid amide is used as the master batch mixed into the ethylene-vinyl acetate copolymer, foaming efficiency is improved and the amount of the azodicarboxylic acid amide used can be limited to a small value. Electrical adverse effects of a decomposition product of the azodicarboxylic acid amide on an insulator can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a foamed vinyl-sheathed wire / cable having a sheath made of a foam of a resin composition mainly comprising a vinyl chloride resin.

[0002]

2. Description of the Related Art Vinyl chloride resin is excellent in terms of electrical insulation, mechanical properties, flexibility, and other costs. Japanese Industrial Standard (JIS K 6723) stipulates that soft vinyl chloride resin is used for electric wires and cables. Vinyl materials are specified. Generally, as a resin composition, 30 to 100 parts by weight of a plasticizer, 1 to 10 parts by weight of a stabilizer, 0 to 100 parts by weight of a filler, and, if necessary, a lubricant and antioxidant, based on 100 parts by weight of a vinyl chloride resin. Compositions containing various additives such as agents are used.

[0003] This soft vinyl chloride resin composition is used in accordance with JIS as an insulator and a sheath for electric wires and cables.
It is a vinyl insulated vinyl sheath cable (VV) defined in C3342. A cable 21 shown in FIG. 1 is a flat vinyl insulated vinyl sheath cable (VVF) obtained by flattening a vinyl insulated vinyl sheathed cable, and an insulated wire core 24 having a conductor 22 coated with a soft vinyl chloride resin composition as an insulator 23. And a sheath 25 coated with a soft vinyl chloride resin composition.

Recently, a foamed vinyl sheathed cable using a vinyl chloride resin foam as the sheath 25 in FIG. 1 has been studied for the purpose of reducing the weight of wires and cables, improving flexibility, and reducing costs.

As a method for foaming a vinyl chloride resin, a method of injecting a gas such as nitrogen, carbon dioxide or a hydrocarbon such as butane, pentane or the like which does not react with the resin in the middle of an extruder and foaming simultaneously with the extrusion, decomposition by heating Alternatively, there is a method of blending a resin with a chemical foaming agent that reacts to generate gas and foaming the resin. Sodium bicarbonate, dinitrosopentamethylenetetramine (DP
T), benzenesulfonyl hydrazide (BSH), azodicarbonamide (ADCA) and the like.

When this chemical foaming agent is blended with a vinyl chloride resin, there has been proposed a method of using a masterbatch in which a high concentration of a chemical foaming agent is kneaded with a vinyl chloride resin in advance (Japanese Patent Laid-Open No. 5-64981). .

[0007]

When the foam ratio of the sheath of a foamed vinyl sheathed electric wire or cable is about 5 to 20%, the effect of tensile strength and oil resistance decrease is less than that of a non-foamed sheath. The effect of cost reduction by using a foam is great. Adjustment of the bubble rate is performed by adjusting the type and the amount of the foaming agent. Among the blowing agents, azodicarbonamide is easy to handle,
It is widely used because the amount of generated gas per unit weight is large. However, when the blending amount of azodicarbonamide is large, there has been a problem that the insulation resistance is reduced when molded into electric wires and cables.

The present invention has been made in order to solve such a problem, and an object of the present invention is to apply a vinyl chloride resin foam using azodicarbonamide as a foaming agent to a sheath and to provide excellent insulation performance. To provide a method for producing a foamed vinyl sheathed electric wire / cable capable of obtaining the following.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, the decomposition product of the foaming agent generated during the molding of the sheath migrates into the insulator and the electrical insulation performance of the insulator is reduced. Have been found to be worse, and the present invention has been completed. That is, in the present invention,
(1) A foamed vinyl sheathed electric wire in which a conductor is coated with a resin composition mainly composed of a vinyl chloride resin, and a foaming agent is blended thereon to form a foamed sheath layer by coating the composition mainly composed of a vinyl chloride resin. In the method for producing a cable, azodicarbonamide is used as the blowing agent, and
A method for producing a foamed vinyl sheathed wire or cable in which the azodicarbonamide is blended with a composition mainly composed of a vinyl chloride resin as a master batch containing an ethylene-vinyl acetate copolymer as a base resin, (2) the vinyl chloride resin composition The amount of azodicarbonamide in the total is 0.00
(1) The method for producing a foamed vinyl sheathed electric wire / cable according to (1), which is 1 to 0.5% by weight, (3) the ethylene-vinyl acetate copolymer has a vinyl acetate content of 5 to 40% (1). Or the foamed vinyl sheathed wire described in (2)
A method of manufacturing a cable is provided.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The sheath of a foamed vinyl sheathed wire / cable according to the present invention is obtained by foaming a flexible vinyl chloride resin composition for wires and cables specified in JIS K 6723. Azodicarbonamide as a foaming agent is used as a masterbatch having an ethylene-vinyl acetate copolymer as a base resin, which is blended with a vinyl chloride resin composition. The appropriate mixing ratio of azodicarbonamide is 1 to 50% by weight of the master batch. Additives such as an antioxidant and a coloring agent may be added to the master batch. The compounding ratio of the azodicarbonamide in the soft vinyl chloride resin composition may be adjusted according to the bubble rate of the sheath, and is suitably 0.001 to 0.5% by weight. In the production method of the present invention, since azodicarbonamide is used as a master batch kneaded with an ethylene-vinyl acetate copolymer, the foaming efficiency can be improved, and the amount of azodicarbonamide used can be extremely small. Therefore, the electrical adverse effect on the insulator due to the decomposition product of azodicarbonamide can be greatly reduced, and a foamed vinyl sheathed wire or cable having excellent electrical insulation properties can be efficiently manufactured.

The production method of the present invention solves the problem that occurs when azodicarbonamide is used as a foaming agent in the conventional method, but p, p'- is used as the foaming agent.
Oxybisbenzenesulfonyl hydrazide (OBSH)
The same effect can be obtained by using such a method.

The ethylene-vinyl acetate copolymer serving as the base resin of the master batch preferably has a vinyl acetate content of 5 to 40% from the viewpoint of compatibility with the vinyl chloride resin and fluidity.

As the ethylene-vinyl acetate copolymer, a commercially available product may be used, and Ultracene 53 manufactured by Tosoh Corporation may be used.
7, Ultra Sen 540, Ultra Sen 541, Ultra Sen 625, Ultra Sen 633, Ultra Sen 68
1. Mitsui Dupont Chemical Co., Ltd. EVAFLEX
P-1207, P-1907, J-LEX EVA DL19-8 manufactured by Japan Polyolefin Co., Ltd., J-LEX EVA DL12-5 and the like.

It is important that the masterbatch be sufficiently dispersed in the vinyl chloride resin composition. The decomposition temperature of azodicarbonamide is around 200 ° C., but when incorporated into a vinyl chloride resin composition, a lead compound or a zinc compound acts as a catalyst to lower the decomposition temperature. For example, when tribasic lead sulfate is blended as a stabilizer, the decomposition temperature of azodicarbonamide decreases to 160 ° C., which is the processing temperature of the vinyl chloride resin composition of 180 ° C.
Decomposition should be sufficient in the range of -200 ° C.
However, if the dispersion is not sufficient, the azodicarbonamide cannot come into contact with the catalyst, resulting in uneven foaming and an uneven bubble diameter. Therefore, it is necessary to sufficiently disperse the master batch.

The soft vinyl chloride resin composition of the present invention generally comprises 30 to 100 parts by weight of a plasticizer, 1 to 10 parts by weight of a stabilizer, 0 to 100 parts by weight of a filler, based on 100 parts by weight of the vinyl chloride resin. Further, those containing various additives and modifiers such as a lubricant, an antioxidant, and a light stabilizer can be used as needed.

The plasticizer is not particularly limited as long as it is used as a plasticizer for the vinyl chloride resin, and examples thereof include phthalic acid, trimellitic acid, adipic acid, and polyester.

Examples of the stabilizer include a lead stabilizer, a Ca / Zn-based stabilizer, a tin-based stabilizer, a phosphite-based stabilizer, and an epoxy compound. As the lead stabilizer, tribasic lead sulfate, tribasic lead maleate, dibasic lead stearate, dibasic lead phthalate, lead white, dibasic lead phosphite,
Basic lead sulfite and the like can be mentioned. Examples of the Ca / Zn-based stabilizer include calcium stearate, calcium ricinoleate, calcium laurate, zinc stearate, zinc ricinoleate, zinc laurate and the like. Others
Alkamizer 1 manufactured by Kyowa Chemical Industry Co., Ltd. as a stabilizer
Hydrotalcite commercially available as Nos. To 5 and perchloric acid type hydrotalcite may be added. Examples of the tin-based stabilizer include organic tin mercaptide, organic tin maleate, and organic tin carboxylate.

The filler is a filler generally used in a vinyl chloride resin composition, such as calcium carbonate, kaolin clay,
Talc and the like. Examples of the calcium carbonate include heavy calcium carbonate obtained by pulverizing natural stones such as limestone, precipitated calcium carbonate obtained by a chemical production method, and the like, and surface-treated calcium carbonate may be used.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments. The material of the soft vinyl chloride resin compound for insulation shown in Table 1 and the material of the soft vinyl chloride resin compound for sheath shown in Table 2 were kneaded with rolls set at 160 ° C., and formed into a sheet having a thickness of 2 mm. To prepare a 2 mm square pellet-shaped soft vinyl chloride resin compound.

[0020]

[Table 1]

[0021]

[Table 2]

Further, four types of masterbatch pellets having the compositions shown in Table 3 were prepared in the same manner as in the case of the soft vinyl chloride compound. In addition, the temperature of the roll at the time of resin kneading,
Master batches 1 to 3 were at 100 ° C, and master batch 4 was at 160 ° C.

[0023]

[Table 3]

(Example 1) A soft vinyl chloride resin compound for insulation was placed on a copper wire having a diameter of 1 mm by an extruder (L / D2).
4, melted and kneaded with a screw diameter of 30 mm).
Extrusion coating was performed at 8 mm to produce an insulated wire core. A resin composition obtained by melt-kneading a soft vinyl chloride resin compound for a sheath and master batch 1 on the insulated wire with an extruder (L / D24, screw diameter 30 mm) at a ratio shown in Table 4 to a thickness of 1.5 mm The foamed sheath layer was formed by extruding and foaming with the above to obtain a foamed sheathed electric wire of Example 1.

(Examples 2 to 5) (Comparative Examples 1 and 2) A foamed vinyl sheathed electric wire was produced in the same manner as in Example 1 except that the masterbatches having the types and amounts shown in Table 4 were used.

With respect to the obtained foamed vinyl sheathed electric wire,
Using the methods and standards described below, measurement of the air bubble ratio and insulation resistance of the sheath layer, and observation of the state of the foam cell were performed. Table 4 shows the results
It is described together.

Bubble ratio of sheath layer: The density of the sheath layer before and after foaming was measured and calculated by the following equation. Bubble ratio (%) = (density before foaming−density after foaming) × 10
0 / density before foaming

Insulation resistance: JIS C 3005 (199
3 years) Measured according to the method of 9.1 (1) (insulation resistance at 20 ° C.).

The state of the foam cell: The cross section of the sheath layer, which appeared when the electric wire was cut perpendicularly to the longitudinal direction, was visually observed, and a fine and uniform one was evaluated as ○, and evaluated on a scale of △, Δ, and ×. .

[0030]

[Table 4]

The foamed vinyl sheathed wires of Examples 1 to 5
The foam ratio of the sheath layer was high, the state of the insulation resistance foam cell was good, and the electrical characteristics were excellent. In particular, in Example 2 using a masterbatch using an ethylene-vinyl acetate copolymer having a vinyl acetate content of 10%, the bubble rate was higher than in Examples 4 and 5 in which the amount of azodicarbonamide added was the same. On the other hand, in Comparative Example 1 using a conventional masterbatch using a vinyl chloride resin as a base resin, the amount of azodicarbonamide was the same as in Examples 2, 4, and 5, but the bubble rate was significantly higher. It is small. In Comparative Example 2 in which the amount of azodicarbonamide added was increased to 5%, a sheath layer having the same bubble ratio as that of Example 2 was obtained, but the insulation resistance was significantly reduced.

[0032]

According to the production method of the present invention, a vinyl chloride resin foam using azodicarbonamide as a foaming agent is applied to a sheath, and a foamed vinyl sheath wire / cable having excellent insulation performance is produced. be able to.

[Brief description of the drawings]

FIG. 1 is an explanatory view illustrating the structure of a vinyl insulated vinyl sheath cable.

[Explanation of symbols]

 21 Cable 22 Conductor 23 Insulator 24 Insulated wire core 25 Sheath

Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // H01B 7/02 H01B 7/02 G (C09D 127/06 123: 08) B29K 27:06 105: 04 B29L 9:00 C08L 27:06

Claims (3)

[Claims] 1. A foaming method in which a conductor is coated with a resin composition mainly composed of a vinyl chloride resin, and a foaming agent is coated thereon to form a foamed sheath layer by coating a composition mainly composed of a vinyl chloride resin. In the method for producing a vinyl sheath electric wire or cable, azodicarbonamide is used as the foaming agent, and the azodicarbonamide is a composition mainly composed of a vinyl chloride resin as a masterbatch having an ethylene-vinyl acetate copolymer as a base resin. A method for producing a foamed vinyl sheathed wire / cable, characterized by being compounded into a product. 2. The compounding ratio of azodicarbonamide in the vinyl chloride resin composition is 0.001 to 0.5% by weight.
The method for producing a foamed vinyl sheathed electric wire / cable according to claim 1, wherein 3. The method according to claim 1, wherein the ethylene-vinyl acetate copolymer has a vinyl acetate content of 5 to 40%.