JPH05325692A - Tube and heat contraction tube - Google Patents

Abstract

PURPOSE:To provide bridged fluorine resin tube and a bridged fluorine resin heat contraction tube that include no problem of necking, and heat resistance for preventing any melt deformation at a temperature above the melting point and can be subjected to melt molding in the case of a tube for protecting the connection part for terminals of an electric wire or cable and a pipe, etc. CONSTITUTION:A tube shaped molded body is made of resin compound mainly including copolymer having repetitive units of ethylene tetra-fluoro-ethylene and fluorine olefin and bridged with the above mentioned resin compound. The tube is formed by being expanded in the diameter direction and fixed thereafter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tube and a heat-shrinkable tube for protecting a connecting portion such as an end of a wire or a cable or a pipe.

[0002]

2. Description of the Related Art Fluororesin is a material having excellent heat resistance and chemical resistance, and is widely applied as a material for a tube or a heat-shrinkable tube that protects terminals of electric wires, cables and connecting portions such as pipes.

Among them, PTFE resin (tetrafluoroethylene resin) has an advantage that it is excellent not only in heat resistance and chemical resistance but also in electrical characteristics, but on the other hand, it is generally difficult to be melt-molded and a tube is manufactured. In this method, a method of press-molding a powder of PTFE resin into a tube shape and sintering the powder particles at a high temperature is used, so that there is a drawback that productivity is low and manufacturing cost is high.

Further, PFA resin (perfluorovinyl ether copolymer) is known as a melt-moldable PTFE resin, but since it is generally difficult to crosslink, it is melt-deformed at a temperature higher than the melting point of the PFA resin. Has the drawback of causing The same applies to a heat shrink tube using PFA resin.

ETFE resin (ethylene tetrafluoroethylene copolymer) has a heat resistance of PTFE resin or P
Although it is inferior to FA resin in one aspect, it has excellent chemical resistance and electrical characteristics and has an advantage that it can be melt-molded. Moreover, when a resin composition obtained by adding a polyfunctional monomer such as triallyl isocyanurate or trimethylolpropane trimethacrylate to an ETFE resin is irradiated with ionizing radiation such as an electron beam, it is melted and deformed even at a temperature higher than its melting point. Since a cross-linked product that does not occur can be obtained, a tube having excellent heat resistance can be obtained, and a heat-shrinkable tube can be obtained by expanding and fixing the diameter in the radial direction after crosslinking.

[0006]

However, the crosslinked product of the above-mentioned crosslinked ETFE resin is disadvantageous in that it is harder than the uncrosslinked product of the ETFE resin. Therefore, cross-linked ETFE
A tube made of resin or a heat-shrinkable tube is apt to buckle (necking). For example, when the product is wound up, if the winding diameter is small, it will buckle and it will be difficult to handle. There was such a problem.

In view of the above problems, the present invention has no necking problem, has heat resistance that does not melt and deform even at a temperature above the melting point, and can be melt-molded to form a crosslinked fluororesin tube and a crosslinked fluororesin heat An object is to provide a shrink tube.

[0008]

In order to solve the above-mentioned problems, the present invention provides a resin composition comprising (1) a copolymer containing ethylene, tetrafluoroethylene and a fluorinated olefin as a repeating unit. A tube-shaped molded article, in which the resin composition is cross-linked, and (2) a tube of a resin composition mainly containing a copolymer having ethylene, tetrafluoroethylene and a fluorinated olefin as a repeating unit. It is a heat-shrinkable tube obtained by expanding and fixing the molded article in a radial direction after crosslinking.

The fluorinated olefin of the copolymer having ethylene, tetrafluoroethylene and fluorinated olefin as a repeating unit according to the present invention is 1,1-dihydroperfluoropropene-1,1,1-dihydroperfluorobutene. -1, hexafluoropropene, 3,3,3-
Trifluoropene, 3,3,3-trifluoro-2-
Examples thereof include trifluoromethylpropene and perfluoroalkyl vinyl ether.

[0010]

[Function] ETFE resin is used in order to crosslink a copolymer having ethylene, tetrafluoroethylene and a fluorinated olefin as a repeating unit by irradiating ionizing radiation such as accelerated electron beam so as to prevent melt deformation even at a temperature above the melting point. It was preferred to add polyfunctional monomers such as triallyl isocyanurate and trimethylolpropane trimethacrylate as well.

In the case of ETFE resin, the addition of a polyfunctional monomer makes it hard after crosslinking and makes necking more likely. However, unlike the case of the ETFE resin, the copolymer containing ethylene, tetrafluoroethylene, and a fluorinated olefin as a repeating unit to which a polyfunctional monomer is added does not become hard even after crosslinking, and even if it is a crosslinked body, necking occurs. It was difficult to obtain a tube or heat-shrink tube with excellent heat resistance.

[0012]

Embodiments of the present invention will be described below.

Using a twin-screw kneading extruder, Table 1 and Table 2
The resin composition described above was kneaded at a discharge part temperature of 240 ° C. to 280 ° C., and the discharge strand was water-cooled and cut into pellets. Next, the above pellets were extruded at an extrusion temperature of 300 to 320 ° C. using a 30 mmφ single screw extruder to obtain a tubular molded product having an outer diameter of 5.0 mmφ and a wall thickness of 0.25 mm. The acceleration voltage is 1 for this tubular molding.
The electron beam of MV was irradiated with 5 Mrad, and the physical properties were compared before and after irradiation.

[0014]

[Table 1]

[0015]

[Table 2]

In Tables 1 and 2, (* 1) is NEOFLON EP610 (trade name) manufactured by Daikin Industries, Ltd., and the fluorine content is 66 wt%. (* 2) is NEOFLON EP620 (trade name) manufactured by Daikin Industries, Ltd., and the fluorine content is 66 wt%. (* 3) is Aflon COP88A (trade name) manufactured by Asahi Glass Co., Ltd.,
The fluorine content is 60 wt%. The softness value of (* 4) is the value obtained by multiplying the 2% modulus by 50, and the smaller this value is, the more flexible it is. (* 5) Necking resistance value is
Based on the presence or absence of buckling when bent 180 ° at 50R, no buckling was good and buckling was bad.

The irradiated tubular molding used in Example 1 was preheated for 3 minutes in a constant temperature bath at 250 ° C., and the outer diameter was expanded to 10 mmφ by a method of applying compressed air to the tube, and then immediately cooled with cold water. It was possible to form a heat-shrinkable tube by fixing with cooling. This heat-shrinkable tube was covered with an aluminum pipe with an outer diameter of 6.0 mmφ and placed in a constant temperature bath at 250 ° C for 1 hour.
After leaving it for a minute and taking it out, it could be shrunk while fitting around the aluminum pipe.

[0018]

As described above, according to the present invention,
There is no necking problem, and it has heat resistance that does not melt and deform even at temperatures above the melting point, and it is possible to obtain melt-moldable cross-linked fluororesin tubes and heat-shrinkable tubes, such as wires and cable terminals and pipes. The utility value of the tube for protecting the connection part and the heat shrink tube is very large.

Claims (2)

[Claims] 1. A tube-shaped molded product of a resin composition mainly comprising a copolymer having ethylene, tetrafluoroethylene and a fluorinated olefin as a repeating unit, wherein the resin composition is crosslinked. 2. A heat-shrinkable tube obtained by cross-linking a tubular molding of a resin composition containing a copolymer containing ethylene, tetrafluoroethylene and a fluorinated olefin as a repeating unit, and then expanding and fixing it in the radial direction. ..