JPH02216705A - Insulated cable coated with elastomer containing fluorine - Google Patents

Abstract

PURPOSE:To increase mechanical strength of an insulated cable by coating it with a composition made by adding specified amounts of silicon dioxide and crosslink assisting agent to a resin containing a copolymer of tetrafluoroethylene and a specific olefin, and ethylene-tetrafluoroethylene- fluoroolefin copolymer. CONSTITUTION:Silicon dioxide by 5-100 weight parts and crosslink assisting agent by 0.5 weight parts or more are added to 100 weight parts of resin composition containing copolymer of tetrafluoroethylene and alpha-olefin of carbon number 2-4, and ethylene-tetrafluroroethylene-fluoroolefin copolymer. This composition is applied over a conductor and crosslinked by irradiating radioactive rays. If the amount of ethylene-tetrafluoroethylene-fluoroolefin copolymer is small, mechanical strength is not improved and if the amount is too much, flexibility is impaired. The mechanical strength is improved within this specified range.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an insulated wire having a fluorine-containing elastomer coating layer with excellent mechanical strength.

[Prior Art] A copolymer of tetrafluoroethylene and an α-olefin having 2 to 4 carbon atoms, especially a tetrafluoroethylene-propylene copolymer, has heat resistance, oil resistance, chemical resistance, and electrical insulation properties. It is excellent for hoses, tubes, gaskets, and gaskets.

It is a material that is expected to be widely applied to diaphragms, sheets, electrical insulation coatings, etc.

Crosslinking of this copolymer is usually carried out by adding a chemical crosslinking agent, molding it into a predetermined shape, and then holding it in a heated atmosphere, but this poses problems in terms of manufacturing efficiency because the crosslinking time is relatively long. be.

For this reason, crosslinking by irradiation with ionizing radiation such as electron beams is being considered.

[Problems to be Solved by the Invention] However, there is a problem in that the crosslinked molded product obtained by irradiation with ionizing radiation does not have sufficient mechanical properties such as tensile strength.

An object of the present invention is to provide a fluorine-containing elastomer-coated insulated wire with significantly improved mechanical strength.

[Means for Solving the Problems] The fluorine-containing elastomer composition of the present invention comprises a copolymer of tetrafluoroethylene and an α-olefin having 2 to 4 carbon atoms, and an ethylene-tetrafluoroethylene-fluoroolefin copolymer. 5 to 100 parts by weight of silicic anhydride and 0 parts by weight of crosslinking aid per 100 parts by weight of the resin component containing
．． It is characterized by having a crosslinked coating layer of a composition containing 5 parts by weight or more.

[Example] In this invention, the α-olefin having 2 to 4 carbon atoms that exhibits elastomeric properties by copolymerizing with tetrafluoroethylene includes propylene and butene-1 alone, ethylene, propylene, butene-1, and isobutene. Examples include combinations of two or more selected from the following, but propylene is preferred in order to achieve the object of the present invention.

The tetrafluoroethylene-propylene copolymer includes, in addition to the main components tetrafluoroethylene and propylene, components copolymerizable with these, such as ethylene,
Contains appropriate amounts of isobutylene, acrylic acid and its alkyl esters, methacrylic acid and its alkyl esters, vinyl fluoride, vinylidene fluoride, hexafluoropropene, chloroethyl vinyl ether, chlorotrifluoroethylene, perfluoroalkyl vinyl ether, etc. There may be.

The tetrafluoroethylene-propylene copolymer is desirably selected from the viewpoint of heat resistance, moldability, etc., with a molar ratio of tetrafluoroethylene/propylene in the range of 95 to 3015 to 70, particularly preferably 90 to 70. 45/
It is 10-55.

Further, the content of components other than the main component, which may be added as appropriate, is preferably selected from a range of 50 mol% or less, particularly 30 mol% or less.

The number average molecular weight of the tetrafluoroethylene-propylene copolymer is preferably from 20,000 to 200,000 in terms of extrudability and mechanical strength; if the number average molecular weight is too large, cracks will easily occur in the molded product. On the other hand, if it is too small, the mechanical strength tends to be insufficient. In this case, the number molecular weight can be adjusted by adjusting the monomer concentration, the polymerization initiator concentration, the monomer to polymerization initiator ratio, the polymerization temperature, the use of a chain transfer agent, etc. A method of directly adjusting the molecular weight of the resulting polymer by manipulating the copolymerization reaction conditions, or a method of producing a high molecular weight copolymer during the copolymerization reaction and reducing the molecular weight by heat treatment in the presence of oxygen. This can be done by

In this invention, the fluoroolefins in the ethylene-tetrafluoroethylene-fluoroolefin copolymer include chlorotrifluoroethylene, vinylidene fluoride, trifluoroethylene, 1,1-dihydroperfluoropropene, 1,1-dihydroperfluoropropene, Butene-1,1,5-trihydroperfluoropentene-
1,1,1,7-trihydroperfluorobentene-1
．． 1. l, 2-1lihydroperfluorohexene-1,
l, l, 2-trihydroperfluorooctene-1, perfluoro(methyl vinyl ether), perfluoro(
ethyl vinyl ether), hexafluoropropene, perfluorobutene-1,3,3,3-trifluoro-2
-trifluoromethylprotin-1 and the like.

The molar ratio of ethylene-tetrafluoroethylene-fluoroolefin is 10-40/90-6010.
．． It is preferable to select from the range of 1 to 20.

The content weight ratio of copolymer of tetrafluoroethylene and α-olefin/ethylene-tetrafluoroethylene-fluoroolefin copolymer is 90 to 20710 to 80, considering the mechanical strength and flexibility of the resulting molded product.
If the content of the ethylene-tetrafluoroethylene-fluoroolefin copolymer is too low, there will be no improvement in mechanical strength, and if the content is too high, the copolymer of tetrafluoroethylene and α-olefin will not be effective. Flexibility, which is the original characteristic of coalescence, tends to be lost.

Melt blending of a copolymer of tetrafluoroethylene and an α-olefin and an ethylene-tetrafluoroethylene-fluoroolefin copolymer is performed by adding a powder of the latter to the former at a temperature below its melting point, for example, 50 to 150°C, using a roll or the like. The mixture may be mixed in a panburr mixer and then molded at a temperature higher than the melting point, or the mixture may be mixed in advance using a roll, panburr, extruder, etc. at a temperature higher than the melting point of the latter.

In this invention, 5 to 100 parts by weight of silicic anhydride is blended with respect to 100 parts by weight of the resin component.
This is to improve the wear resistance of the composition. If it is less than 5 parts by weight, the effect of improving wear resistance will be small, and if it exceeds 100 parts by weight, the tensile properties will be significantly lowered.

Although some fillers other than the amount of silicic anhydride have the effect of improving wear resistance, silicic anhydride is particularly preferred because it does not significantly reduce the tensile properties even when added in a large amount.

In this invention, a crosslinking aid is added to increase the crosslinking reactivity, and the crosslinking aid includes triallyl isocyanurate, triallyl cyanurate, triallyl trimellitate, tetraallyl pyromellitate, etc. The amount of the crosslinking aid, which is particularly preferably an allyl type compound, is 0.5 parts by weight or more, preferably 0.5 to 10 parts by weight, based on 100 parts by weight of the resin component. If the amount is less than 0.5 parts by weight, it is difficult to obtain sufficient mechanical strength, and if the amount is 10 parts by weight, the effect of adding the crosslinking aid is saturated.

In addition to the above ingredients, stabilizers and pigments such as titanium white.

Various additives such as antioxidants, plasticizers, and lubricants can be added.

Examples 1 to 4 and Comparative Examples 1 to 2 in Table 1
The components shown in each column are melted and mixed using a kneader. This compound is heated at 250℃, head: 250℃
, Cylinder 1: 180℃, Cylinder 2: 250
40mm extruder (L/D=22) set at each temperature of °C
was used to coat a conductor (tin-plated copper aggregate stranded wire) with an outer diameter of 1.6 mm in a thickness of 1.0 mm, and then cross-linked by irradiating it with an electron beam of 5 Mrad to prepare a sample.

The results of measuring the tensile properties and abrasion resistance of the insulated wires on each side produced as described above are shown in the lower column of Table 1.

Wear resistance is passed if a jig with three 90-degree edge blades with a 2-bond load is moved back and forth over the wire, and the number of times until the edge and the conductor become electrically connected is 100 times or more. , if it was less than 100 times, it was judged as a failure.

(Left below) *4 Ethylene/tetrafluoroethylene/l, molar ratio of 1-dihydroperfluorobutene-1 content = 34/64/
4 Examples 1 to 4 within the scope of the present invention all exhibit excellent tensile properties and abrasion resistance. On the other hand, in Comparative Example 1, the content of silicic anhydride was lower than the specified value of the present invention, the tensile strength was low, and the abrasion resistance was rejected.

In addition, in Comparative Example 2, the content of silicic anhydride exceeds the specified value of the present invention, the tensile strength and elongation are significantly reduced, and the abrasion resistance is also unacceptable.

[Effects of the Invention] As explained above, the fluorine-containing elastomer-coated insulated wire of the present invention contains tetrafluoroethylene and a carbon number of 2 to 2.
It has a crosslinked coating layer of a composition containing a copolymer with an α-olefin in No. 4, an ethylene-tetrafluoroethylene-fluorotetraolefin copolymer, and silicic anhydride, and the mechanical properties of the fluorine-containing elastomer coating layer It becomes possible to significantly improve strength.

Claims (5)

[Claims] (1) Add 5 parts by weight of silicic anhydride to 100 parts by weight of a resin component containing a copolymer of tetrafluoroethylene and an α-olefin having 2 to 4 carbon atoms and an ethylene-tetrafluoroethylene-fluoroolefin copolymer. A fluorine-containing material, characterized in that a coating layer of a composition containing ~100 parts by weight and 0.5 parts by weight or more of a crosslinking aid is formed on the outer periphery of the conductor, and this coating layer is crosslinked by irradiation with radiation. Elastomer coated insulated wire. (2) The content weight ratio of copolymer of tetrafluoroethylene and α-olefin having 2 to 4 carbon atoms/ethylene-tetrafluoroethylene-fluoroolefin copolymer is 90
The fluorine-containing elastomer coated insulated wire according to claim 1, wherein the fluorine-containing elastomer-coated insulated wire has a ratio of . (3) The fluorine-containing elastomer-coated insulated wire according to claim 1, wherein the α-olefin is propylene. (4) The fluorine-containing elastomer-coated insulated wire according to claim 3, wherein the molar ratio of tetrafluoroethylene/propylene is 95-30/5-70. (5) The molar ratio of ethylene/tetrafluoroethylene/fluoroolefin is 10 to 40/90 to 60/0.
2. The fluorine-containing elastomer-coated insulated wire according to claim 1, which has a molecular weight of 1 to 20.