JPH0668938B2 - Method for manufacturing foam insulated wire - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a conductor and a foam insulated wire.

[Prior Art] In a high-speed information circuit such as a computer and a telephone communication, an electric wire having a low dielectric constant is required, and a foamed polyolefin insulated electric wire is often used. As a method for producing a foamed polyolefin insulated wire, a method is generally known in which a polyolefin containing a chemical foaming agent is supplied to an extruder, melt-kneaded at a temperature equal to or higher than the decomposition temperature of the foaming agent, and extrusion-coated on the outer circumference of the conductor. However, in this method, the decomposition gas of the foaming agent is easily scattered, and it is difficult to obtain a high-foamed product of 50% or more.

As a measure to prevent the decomposition gas of the foaming agent from scattering,
53-4909 proposes a manufacturing method in which a plastic mixture containing a foaming agent is extrusion-coated on a conductor, continuously cross-linked by radiation and electron beams, and then heated in a pressurized fluid atmosphere to foam. Has been done.

[Problems to be Solved by the Invention] However, this method lacks versatility because a fluid pressurizing facility is required, and the outer diameter is not uniform due to pressure fluctuation, and the insulated wire is contaminated by fluid. There are problems such as.

For this reason, various studies were conducted on heat foaming under normal pressure. When the most suitable azodicarbonamide was used as a foaming agent, the conductor and the foamed insulation adhered to each other, and the foamed insulation was peeled off using a wire stripper. In this case, there is a problem that the foamed insulator remains around the conductor and the workability of the terminal treatment is extremely deteriorated.

As a method of suppressing the adhesion between the conductor and the foamed insulator to improve the workability of the terminal treatment, zinc soap such as zinc stearate,
It has been confirmed that adding a small amount of lead soap such as lead stearate is effective. However, the addition of such a compound lowers the decomposition temperature of azodicarbonamide and makes it easier to decompose, so the extrusion conditions of the compound become strict, and it is possible to produce a uniform foam insulated wire over a long length. The problem of becoming difficult has come to the fore.

The present invention has been made based on the above, high foaming is possible, the adhesion of the conductor and the foamed insulation is suppressed, and the foamed insulation is easily peeled off, and the foamed insulation is uniform over a long length. It is an object of the present invention to provide a method for producing a foam insulated wire from which a body is obtained.

[Means for Solving Problems] The method for producing a foam insulated wire according to the present invention is a polyolefin 10
0.5 to 15 parts by weight of azodicarbonamide to 0 parts by weight,
A compound containing 0.1 to 10 parts by weight of an organozinc compound and 0.05 to 5 parts by weight of a fatty acid is extrusion-coated on the outer circumference of a conductor at a temperature not higher than the decomposition temperature of azodicarbonamide, and then crosslinked by irradiation with ionizing radiation, and then azodicarbonate. It is characterized in that the foamed insulator is formed by heating at a temperature equal to or higher than the decomposition temperature of the amide.

Examples of the polyolefin in the present invention include, but are not limited to, low density polyethylene, medium and high density polyethylene, linear low density polyethylene, ultra low density polyethylene, polypropylene and the like.

Azodicarbonamide is a powder substance having a decomposition temperature of 200 to 210 ° C., and a gas generated by the decomposition forms a foam. The amount of azodicarbonamide added should be in the range of 0.5 to 15 parts by weight with respect to 100 parts by weight of the polyolefin.If it is less than 0.5 parts by weight, the foaming is insufficient. Becomes difficult.

In the present invention, the combined use of the organozinc compound and the fatty acid can suppress the adhesion between the conductor and the foamed insulation, and can form a foamed insulation that is uniform over a long length. That is, when the compound is extruded, the organozinc compound and the fatty acid rarely lower the decomposition temperature of the azodicarbonamide because they are simply in a dispersed state, and the organozinc compound and the fatty acid react during the heat foaming, It is considered that this suppresses the generation of decomposition residues of azodicarbonamide, which contributes to the adhesion between the conductor and the foamed insulator.

The addition amount of the organic zinc compound and the fatty acid is 0.1 to 10 parts by weight and 0.05 parts by weight, respectively, relative to 100 parts by weight of the polyolefin.
Is in the range of 5 parts by weight. If the organozinc compound is less than 0.1 parts by weight or the fatty acid is less than 0.05 parts by weight, the effect of preventing the adhesion between the conductor and the foamed insulator is ineffective. In addition, the organozinc compound is 10
If the weight part or the fatty acid exceeds 5 parts by weight, the decomposition temperature of azodicarbonamide is remarkably lowered, so that it becomes difficult to obtain a foamed insulator which is foamed during extrusion molding and is uniform over a long length. It is difficult to obtain a foam insulation.

As the organic zinc compound, a zinc salt of 2-mercaptobenzothiazole, zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc N-ethyl-N-phenyldithiocarbamate, zinc butylxanthate, a zinc salt of 2-mercaptobenzimidazole, 2-
Examples thereof include zinc salt of benzamide thiophenol, zinc di-n-butyldithiocarbamate, zinc dibenzyldithiocarbamate, zinc acetate, and basic zinc acetate.

As the fatty acid, stearic acid, lauric acid, ricinoleic acid, naphthenic acid, 2-ethylhexoic acid, octylic acid, hydroxystearic acid, phthalic acid, lindelic acid,
Elaidic acid, tudzuic acid, gadrenic acid, ficetrain acid, gondoic acid, myristoleic acid, whale oil acid, zomarinic acid, erucic acid, petroselinic acid, planzic acid, oleic acid, serracoylenic acid, linoleic acid, linoelaidic acid, linolenic acid Acid, eleostearic acid, moloctic acid, vinalinaric acid, arachidonic acid, sardine acid, hiragashilaic acid,
Examples include nisinic acid.

The compound containing polyolefin, azodicarbonamide, organozinc compound and fatty acid as essential components is melt-kneaded at a temperature not higher than the decomposition temperature of azodicarbonamide, for example at a temperature not higher than 160 ° C., and extrusion-coated on the outer periphery of the conductor. Next, 0.5 to 0.5
Irradiation is performed in the range of 5 Mrad to crosslink, and the foamed insulator is formed by heating under normal pressure to a temperature above the decomposition temperature of azodicarbonamide. This heating is preferably performed continuously using an electric furnace or the like, and the set temperature is preferably several tens of degrees higher than the decomposition temperature of azodicarbonamide. Of course, the high temperatures at which the polyolefin decomposes should be avoided.

As a method for obtaining a compound containing a polyolefin, an azodicarbonamide, an organozinc compound and a fatty acid, azodicarbonamide, an organozinc compound and a fatty acid are added to a polyolefin and mixed, respectively, and an azodicarbonamide and an organozinc compound are added to the polyolefin. A method of mixing a mixture obtained by adding azodicarbonamide and a fatty acid to a polyolefin, a mixture obtained by adding one of an organozinc compound or a fatty acid to a polyolefin, and a polyolefin Examples of the method include, but are not limited to, a method of mixing azodicarbonamide with the remaining organozinc compound or a mixture of fatty acids and a mixture thereof.

[Examples of the invention] Example 1 100 parts by weight of low-density polyethylene (UBE-400, Ube Industries) and 3 parts by weight of azodicarbonamide and zinc salt of 2-mercaptobenzimidazole (Ouchi Shinko Nocrac MBZ) 1
1 part by weight was added, and this was kneaded with an 8-inch roll set at 135 ° C., and then 0.5 parts by weight of stearic acid was added to obtain a compound. This compound was introduced into a 28 mm extruder (set temperature 140 ° C.) and melt-kneaded, and the outer circumference of a tin-plated copper wire having an outer diameter of 0.45 mm was extrusion-coated to a thickness of 0.2 mm. Then, 1.5 Mrad was irradiated by an electron beam irradiation device to perform cross-linking, and the product was passed through a tubular electric furnace having an inner diameter of 70 mmφ and a furnace length of 2.5 m set at 300 ° C. under normal pressure to manufacture a foam insulated wire.

The degree of foaming of this insulated wire was about 73%, and it was extremely easy to peel off the foamed insulation with a wire stripper. Further, since the foaming was performed uniformly in the length direction, there was almost no fluctuation in the outer diameter in the length direction.

Example 2 100 parts by weight of low-density polyethylene (Mitsui Petrochemical Mirason 3530), 4 parts by weight of azodicarbonamide and zinc salt of 2-mercaptobenzothiazole (Ouchi Shinko Noxcellar M
Z) 2 parts by weight was kneaded with an 8-inch roll set at 130 ° C., and then 0.5 part by weight of ricinoleic acid was added to obtain a compound. Subsequently, using a 28 mm extruder (set temperature 135 ° C.), a foam insulated wire was manufactured in the same manner as in Example 1.

The degree of foaming of this insulated wire was about 75%, and it was extremely easy to peel off the foamed insulator with a wire stripper. Further, since the foaming was performed uniformly in the length direction, there was almost no fluctuation in the outer diameter in the length direction.

Example 3 A foam insulated wire was produced in the same manner as in Example 1 except that zinc acetate was used instead of the zinc salt of 2-mercaptobenzimidazole.

The degree of foaming of this insulated wire was about 73%, and it was extremely easy to peel off the foamed insulation with a wire stripper. Further, since the foaming was performed uniformly in the length direction, there was almost no fluctuation in the outer diameter in the length direction.

Example 4 An 8-inch roll set to 135 ° C. by adding 3 parts by weight of azodicarbonamide and 1.5 parts by weight of zinc dimethyldithiocarbamate (Ouchi Shinko Nocceller PZ) to 100 parts by weight of low-density polyethylene (Mitsui Petrochemical Mirason 3530). And kneaded to obtain a composition. In addition, 100 parts by weight of low-density polyethylene (Mitsui Petrochemical Mirason 3530) was added to azodicarbonamide 3
1 part by weight and 0.8 part by weight of stearic acid were added and kneaded with an 8-inch roll set at 135 ° C. to obtain a composition. 28 mm extruder (set temperature 140 ° C) after pelletizing each of the above two compositions and dry blending at a ratio of 50:50
And the foam insulated wire was manufactured in the same manner as in Example 1.

The degree of foaming of this insulated wire was about 72%, and it was extremely easy to peel off the foamed insulation with a wire stripper. Further, since the foaming was performed uniformly in the length direction, there was almost no fluctuation in the outer diameter in the length direction.

Comparative Example 1 A foam insulated wire was produced in the same manner as in Example 1 except that a compound obtained by adding 3 parts by weight of azodicarbonamide to 100 parts by weight of low-density polyethylene (UBEC-400 manufactured by Ube Industries) was used.

The degree of foaming of this insulated wire was about 70%, but the conductor and the foamed insulator adhered to each other, and when the foamed insulation was stripped with a wire stripper, the foamed insulation remained on the conductor.

Comparative Example 2 A foamed insulated electric wire was prepared in the same manner as in Example 1 except that 4 parts by weight of azodicarbonamide and 0.5 parts by weight of zinc stearate were added to 100 parts by weight of low-density polyethylene (Mitsui Petrochemical Mirason 3530). Manufactured.

The degree of foaming of this insulated wire was about 73%, and it was extremely easy to peel off the foamed insulation with a wire stripper. However, the foaming was non-uniform, and the variation of the outer diameter in the length direction was large.

Comparative Example 3 100 parts by weight of low-density polyethylene (Mitsui Petrochemical Mirason 3530), 3 parts by weight of azodicarbonamide and zinc salt of 2-mercaptobenzimidazole (Ouchi Shinko Nokrac
A foam insulated wire was produced in the same manner as in Example 1 except that the compound containing 2 parts by weight of MBZ) was used.

The degree of foaming of this insulated wire was about 76%, but the conductor and the foamed insulation adhered to each other, and when the foamed insulation was stripped off with a wire stripper, the foamed insulation remained on the conductor.

Comparative Example 4 A foam insulated wire was produced in the same manner as in Example 1 except that a compound obtained by adding 3 parts by weight of azodicarbonamide and 0.5 part by weight of stearic acid to 100 parts by weight of low-density polyethylene (Mitsui Petrochemical Mirason 3530) was used. did.

The degree of foaming of this insulated wire was about 75%, but when the conductor and the foamed insulation adhered and the foamed insulation was stripped off with a wire stripper, the foamed insulation remained on the conductor.

[Effects of the Invention] As described above, according to the present invention, it is possible to achieve high foaming, prevent the adhesion between the conductor and the foamed insulating material, and improve the workability of the terminal treatment, and moreover, it is uniform over a long length. It becomes possible to realize a foam insulated wire having an outer diameter.

Front Page Continuation (72) Inventor Shiro Konishi 5-1-1 Hidaka-cho, Hitachi City, Ibaraki Hitachi Cable Electric Wire Co., Ltd. (72) Inventor Shoji Endo 5-1-1 Hidaka-cho, Hitachi City, Ibaraki Prefecture No. Hitachi Cable Co., Ltd. Electric Wire Research Laboratory (72) Inventor Hirotoshi Okubo 5-1-1 Hidakacho, Hitachi City, Ibaraki Prefecture Hitachi Cable Co., Ltd. Electric Cable Research Laboratory (56) Reference JP-A-63-304533 A)

Claims (1)

[Claims] 1. Azodicarbonamide 0.5 to 15 parts by weight, organozinc compound 0.1 to 10 relative to 100 parts by weight of polyolefin.
Parts by weight and a compound containing 0.05 to 5 parts by weight of fatty acids are extrusion-coated on the outer circumference of the conductor at a temperature not higher than the decomposition temperature of azodicarbonamide, and then crosslinked by irradiation with ionizing radiation, and then at a temperature not lower than the decomposition temperature of azodicarbonamide. A method for producing a foam insulated wire, which comprises heating to form a foam insulator.