JPS6030694B2 - Method for manufacturing fluororesin crosslinked molded product - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for obtaining a crosslinked fluororesin molded product having excellent mechanical properties in a high temperature atmosphere.

Ethylene-fluoroolefin copolymer is a well-balanced material that has particularly excellent mechanical properties and processability among fluororesins, as well as excellent electrical properties, chemical resistance, and heat resistance.

For this reason, it is widely used in various fields, including as a material for covering electric wires, as well as in the form of films and tubes. However, when the ethylene-fluoroolefin copolymer is placed in an atmosphere at a high temperature exceeding its melting point, it deforms due to external force, which limits its use at high temperatures. In order to improve this, attempts have been made to crosslink the copolymer by irradiating it with radiation such as electron beams, but the ethylene-fluoroolefin copolymer deteriorates due to irradiation with radiation and becomes weak in strength.

For this reason, a crosslinking agent such as a furyl type compound is added to the ethylene-fluoroolefin copolymer. However, when a crosslinking agent is added to an ethylene-fluoroolefin copolymer and extrusion molded, the crosslinking agent causes a chemical reaction in the ethylene-fluoroolefin copolymer, causing the resulting molded product to have a rough appearance. There is a problem that good products cannot be obtained.

The present invention solves the problems of the prior art described above, and provides a method for obtaining a crosslinked fluororesin molded product that has a good product appearance and excellent mechanical properties in a high-temperature atmosphere.

That is, in the present invention, 0.5 to 50 parts by weight of a fluorine-containing elastomer and a crosslinking agent are added to 10 parts by weight of an ethylene-fluoroolefin copolymer, and the resulting mixture is introduced into an extruder and extruded while being melt-kneaded. This method is characterized in that an extrusion molded product is obtained, and then crosslinked by irradiation with an electron beam. Examples of the ethylene-fluoroolefin copolymer include alternating copolymers of ethylene and tetrafluoroethylene and alternating copolymers of ethylene and chlorotrifluoroethylene.

Fluorine-containing elastomers are not particularly limited, and include tetrafluoroethylene-propylene copolymers, pinylidene fluoride-hexafluoropobene copolymers,
Vinylidene fluoride-chlorotrifluoroethylene copolymer, pinylidene fluoride-pentafluoroproben copolymer, polyfluoroalkyne group-containing acrylate elastomer, polyfluoroalkyne group-containing polysiloxane elastomer, tetrafluoroethylene Vinylidene fluoride-propylene copolymer, tetrafluoroethylene-ethylene-isobutylene copolymer, ethylene-
Hexafluoroproben copolymer, tetrafluoroethylene-butene-1 copolymer, tetrafluoroethylene-ethyl vinyl ether copolymer, fluorine-containing phosphonitrile elastomer, tetrafluoroethylene- Examples include fluorovinyl ether copolymers. Among these, tetrafluoroethylene-propylene copolymers are particularly suitable, and the molar ratio of tetrafluoroethylenenopropylene can be selected from the range of 95/5 to 30/70, particularly 90/10 to 45/55. preferable.

In addition to the main components tetrafluoroethylene and propylene, components that can be copolymerized with these, such as ethylene, isobutylene, acrylic acid and its alkyl esters, methacrylic acid and its alkyl esters, vinyl fluoride, vinylidene fluoride, hexafluoride, etc. It may contain fluoropoben, chloroethyl vinyl ether, chlorotrifluoroethylene, perfluoroalkyl vinyl ether, etc., and the content of components other than the main component that may be added as appropriate is 50%. It is preferable to select from a range of mol % or less, particularly 30 mol % or less.

Examples of the crosslinking agent include allyl type compounds (compounds containing an allyl group), and triallyl cyanurate and triallyl isocyanurate are preferred.

Others include triallyl trimellitate, triallyl trimesate, and tetraallyl pyromellitate. The fluorine-containing elastomer must be mixed in an amount of 0.5 to 5 parts by weight based on 10 parts by weight of the ethylene-fluoroolefin copolymer.

If it is less than 0.5 parts by weight, the extruded appearance cannot be improved, and if it exceeds 5 parts by weight, the mechanical properties under high temperature atmosphere will be impaired.

Further, the crosslinking agent is generally mixed in an amount of 11 to 20 parts by weight based on 10 parts by weight of the ethylene-fluoroolefin copolymer.

In addition, metal oxides, inorganic fillers,
Coloring agents etc. can also be added.

Experiments conducted by the inventor have confirmed that the molded product obtained by introducing predetermined amounts of the various components described above into an extruder and extruding the molded product while melt-mixing has an extremely smooth appearance. In particular, it has been confirmed that by uniformly mixing the fluorine-containing elastomer and the crosslinking agent in advance and introducing this into an extruder together with the ethylene-fluoroolefin copolymer, an extruded product with a particularly excellent appearance can be obtained. There is.

Examples of the present invention will be described below while comparing them with comparative examples.

Various components were introduced into an extruder (40/machine, L/D = 2 stop compression ratio = 3) at the mixing ratio shown in each example in Table 1, and an extruder with an outer diameter of 0.8 ribs was introduced under the following conditions. The outer periphery of the conductor was coated by extrusion to a thickness of 0.2 mm (triallysonurate and tetrafluoroethylene copolymer were mixed in advance and then introduced into the extruder).

Temperature of barrel zone 1 260 pm Temperature of barrel zone 2 27 pm Temperature of barrel zone 3 2800 Crosshead temperature 320°C Die temperature 320°C Screw rotation speed 19 counter rotation/min then 1
A crosslinked insulated wire was obtained by irradiation with an electron beam of 0 MMd.

The test results for the insulated wire thus obtained are shown in the lower column of Table 1.

The extruded appearance is the result of visual observation of the insulated wire after extrusion, and the heat deformation rate is according to JISC3005.
These are the results measured at 330°C.

Table 1 [Amounts are in parts by weight] Asahi Glass Co., Ltd. Afflon COP C-8 Ship'2 Asahi Glass Co., Ltd. Aflas 100 From Table 1, the insulated wire obtained by the present invention has a good appearance. Moreover, it can be seen that it is difficult to deform even at a high temperature of 330 degrees Celsius.

Claims (1)

[Scope of Claims] 1. A mixture of 100 parts by weight of an ethylene-fluoroolefin copolymer, 0.5 to 50 parts by weight of a fluorine-containing elastomer, and a crosslinking agent is introduced into an extruder, and extruded while melt-kneading. 1. A method for producing a crosslinked fluororesin molded product, which comprises obtaining an extrusion molded product and then crosslinking it by irradiating it with an electron beam. 2. Mix the fluorine-containing elastomer and the crosslinking agent in advance,
2. The method for producing a crosslinked fluororesin molded article according to claim 1, which comprises introducing this into an extruder together with the ethylene-fluoroolefin copolymer. 3 The fluorine-containing elastomer is tetrafluoroethylene.
3. The method for producing a crosslinked fluororesin molded article according to claim 1 or 2, which is a propylene copolymer. 4. The method for producing a crosslinked fluororesin molded article according to claim 1, 2, or 3, wherein the crosslinking agent is an allyl type compound.