JPH0467284B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to electric wires and cables having a coating layer of a fluorine-containing elastomer, particularly a tetrafluoroethylene-propylene copolymer. [Prior Art] Tetrafluoroethylene-propylene copolymers are used in a variety of applications such as gaskets, packing, and diaphragms due to their excellent heat resistance, oil resistance, chemical resistance, electrical insulation properties, etc. It is also a promising material as an electrical insulating material such as a wire covering material. However, there is a contradictory relationship between the extrusion processability of such copolymers and the mechanical strength of the resulting molded products.
If a high molecular weight material is used to increase mechanical strength, there is a problem that extrusion processability is lowered and the appearance is deteriorated. [Problems to be solved by the invention] The present invention has been made based on the above, and includes:
Fluorine-containing elastomer-coated electric wire that can improve the mechanical strength of the coating layer without reducing extrusion processability.
The purpose is to provide cables. [Means for Solving the Problems] The fluorine-containing elastomer-coated electric wire/cable of the present invention uses vinylidene-6 fluoride having a number average molecular weight of 5,000 or less based on 100 parts by weight of a tetrafluoroethylene-propylene copolymer. An extrusion coating layer of a composition containing 5 parts by weight or more of a fluorinated propylene copolymer is provided on the circumference of the conductor or on the circumference of the insulated wire core, and the coating layer is crosslinked. . In the present invention, the tetrafluoroethylene-propylene copolymer includes, in addition to the main components tetrafluoroethylene and propylene, components copolymerizable with these, such as ethylene and butene.
1. Appropriately containing isobutene, acrylic acid and its alkyl esters, vinyl fluoride, vinylidene fluoride, hexafluoropropene, chloroethyl vinyl ether, glycidyl vinyl ether, chlorotrifluoroethylene, perfluoroalkyl vinyl ether, etc. Good too. In such a copolymer, the molar ratio of tetrafluoroethylene/propylene is 95/5.
~30/70, especially from the range of 90/10 to 45/55 is preferable from the viewpoint of heat resistance, moldability, etc. Also, the content of components other than the main component that may be added as appropriate is usually 50 mol. % or less, particularly preferably 30 mol% or less. The number average molecular weight of such a copolymer is preferably 20,000 to 150,000 from the viewpoint of extrudability and mechanical strength; if the number average molecular weight is too large, cracks will easily occur in the molded product, while if it is too small and mechanical strength is likely to be insufficient. In this case, the molecular weight may be adjusted by direct synthesis or by treating the polymer under pressure with oxygen to lower the molecular weight. In the present invention, the vinylidene fluoride-propylene hexafluoride copolymer may contain other components such as ethylene tetrafluoride in addition to this component.
The vinylidene fluoride-propylene hexafluoride copolymer must have a number average molecular weight of 5,000 or less; if it exceeds this, extrusion processability decreases and the appearance deteriorates. A composition containing a tetrafluoroethylene-propylene copolymer and a vinylidene fluoride-hexafluoride propylene copolymer is extrusion coated on the outer periphery of a conductor or an insulated wire core, and then crosslinked. Therefore, peroxides are suitable as crosslinking agents, such as dicumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)benzene, 1,3-bis(t-butylperoxy), isopropyl)benzene, t-butylcumyl peroxide, di-t-butyl peroxide, 2,5
-dimethyl-2,5-di(t-butylperoxy)hexyne-3,2,2-di(t-butylperoxy)butane and the like. These can be used alone or in combination of two or more, and the amount added is usually 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, per 100 parts by weight of the resin component. In the present invention, it is possible to use a crosslinking aid in addition to the crosslinking agent, and such crosslinking aids include serial phthalates, triallyl phosphate, triallyl cyanurate, triallyl isocyanurate, and the like. The amount of the crosslinking aid additive is 0.1 to 20 parts by weight, preferably 0.2 to 10 parts by weight, based on 100 parts by weight of the resin component. In addition to the above-mentioned components, the composition usable in the present invention can also contain a metal compound as a stabilizer, carbon black, calcium carbonate, magnesium silicate, etc. as a filler. [Example] Various ingredients were mixed in the proportions shown in each example in Table 1 and kneaded for 15 minutes using a 6-inch roll maintained at 50 to 60°C. Next, head: 100℃, cylinder 1: 80℃,
Cylinder 2: Introduced into a 50 m/m extruder (L/D = 18) set at 60°C, coated on the outer circumference of a copper wire with an outer diameter of 2.0 mm to a thickness of 1 mm, and then heated in 13 atm steam for 30 minutes.
It was held for a minute to crosslink. The evaluation results regarding the extrusion appearance and tensile strength of the obtained covered wire are shown in the lower column of Table 1.

【table】

[Table] As is clear from Table 1, all of Examples 1 to 3 within the scope of the present invention had good extrusion processability, good extrusion appearance, and excellent tensile strength. In Comparative Example 1, the content of the vinylidene fluoride-propylene hexafluoride copolymer was less than the specified value of the present invention, and in Comparative Example 2, the number average molecular weight of the vinylidene fluoride-propylene hexafluoride copolymer was lower than the specified value of the present invention. These values exceed the specified values of the present invention, and the extrusion appearance is poor in both cases. [Effects of the Invention] As explained above, according to the present invention, it is possible to obtain a fluorine-containing elastomer-coated electric wire/cable having a coating layer with excellent mechanical strength without impairing extrusion processability.

Claims (1)

[Claims] 1. An extruded coating layer of a composition containing 5 parts by weight or more of a vinylidene fluoride-propylene hexafluoride copolymer with a number average molecular weight of 5000 or less per 100 parts by weight of a tetrafluoroethylene-propylene copolymer is a conductor. A fluorine-containing elastomer-coated electric wire/cable, which is provided on the periphery or on the periphery of an insulated wire core, and the coating layer is crosslinked.