JPH0238085B2 - SHOSHAKAKYONANNENSEITOMEIJUSHISEIKEITAINOSEIZOHOHO - Google Patents

Description

[Detailed description of the invention]

[Background and Objectives of the Invention] The present invention relates to a method for producing a crosslinked molded article having excellent flexibility, transparency, and flame retardancy. For example, when using heat-shrinkable tubes to connect internal wiring in equipment or to process terminals, it is better to use heat-shrinkable tubes that have excellent transparency because the condition of the connections can be visually checked.
It is required to be highly flexible for ease of handling, and to be flame retardant in the event of a fire. Therefore, polyvinyl chloride resins, which have excellent transparency and flame retardancy, have been used for applications in this field. In this case, the plasticity added to give flexibility oozes out and contaminates the equipment surface, or the plasticizer often migrates to the insulated wire that is the adherend of the tube. A plastic type heat shrink tube was desired. However, polyethylene, which is a non-plastic type resin, or a copolymer mainly composed of ethylene has poor flame retardancy, and when a flame retardant is added to make it flame retardant, transparency is impaired. Further, although polyvinylidene fluoride resin has excellent flame retardancy and transparency, it is hard and therefore not suitable for use in moving parts. The present invention is based on the above, and aims to provide a crosslinked molded article having excellent flexibility, transparency, and flame retardancy. [Summary of the invention] The present invention provides polyester thermoplastic elastomer
Molding a resin composition containing 0.5 to 15 parts by weight of a polyfunctional monomer to 100 parts by weight of a resin component containing 20 to 80% by weight and 80 to 20% by weight of polyvinylidene fluoride,
It is characterized by being crosslinked by irradiation with ionizing radiation. In the present invention, the polyester thermoplastic elastomer is blended to impart flexibility to polyvinylidene fluoride without impairing its transparency and flame retardancy. The blending ratio of polyester thermoplastic elastomer and polyvinylidene fluoride must be 20-80/80-20 by weight.
If the amount of polyester thermoplastic elastomer is less than 20% by weight, sufficient flexibility cannot be obtained, and if it exceeds 80% by weight, flame retardancy will be reduced. The polyfunctional monomer is added to improve the crosslinking efficiency of the molded product, and it is necessary to add 0.5 to 15 parts by weight per 100 parts by weight of the resin component consisting of the polyester thermoplastic elastomer and polyvinylidene fluoride. If the amount of the polyfunctional monomer added is less than 0.5 parts by weight, a sufficient degree of crosslinking cannot be achieved, and the effect of improving the degree of crosslinking is saturated at about 15 parts by weight. Examples of polyfunctional monomers include acrylates (diethylene glycol diacrylate, etc.), dimethacrylates (diethylene glycol dimethacrylate, dipropylene glycol dimethacrylate, etc.), triacrylates (trimethylolethane triacrylate, trimethylolbutane triacrylate, etc.) ), trimethacrylates (trimethylolethane trimethacrylate,
(trimethylolpropane trimethacrylate, etc.), triallyl cyanurate, triallyl isocyanurate, diallyl maleate, etc. Note that polyfunctional monomers are difficult to disperse uniformly in polyvinylidene fluoride, so the polyfunctional monomer is kneaded into polyester thermoplastic elastomer and mixed uniformly, and this is mixed together with polyvinylidene fluoride in a mixing machine such as a tumbler. It is preferable to mix it uniformly. A resin composition containing a polyester thermoplastic elastomer, polyvinylidene fluoride, and a polyfunctional monomer is formed into a predetermined shape using an extruder, and then crosslinked by irradiation with ionizing radiation such as an electron beam. Although the present invention is applicable to the production of various crosslinked molded bodies, it is particularly suitable for the production of heat-shrinkable tubes. Heat-shrinkable tubes are manufactured by expanding the tube at a temperature above the softening point or melting point and then cooling it, but the tube cannot be expanded at temperatures above the softening point or melting point because the resin melts. . For this reason, crosslinking is performed to prevent the tube from melting. Crosslinking methods include chemical crosslinking, ionizing radiation crosslinking, etc., but chemical crosslinking is impossible because there is no organic peroxide that can withstand the molding temperature of polyvinylidene fluoride. Therefore, in the present invention, crosslinking by irradiation with ionizing radiation is employed. [Examples of the Invention] Resin compositions containing various components as shown in Table 1 were prepared. In this case, a polyester thermoplastic elastomer and a polyfunctional monomer (trimethylolpropane trimethacrylate, triallyl isocyanurate) were mixed uniformly, and then mixed with polyvinylidene fluoride. The above resin composition is formed into a sheet by pressing,
It was crosslinked by electron beam accelerator irradiation. The evaluation results for the sheets of each example are as shown in the lower column of Table 1. The evaluation was based on the following. Combustion test: A 2 mm thick sheet was irradiated with 5 Mrad using a 1.5 MeV electron beam accelerator, and then evaluated based on ASTMD635. Transparency: Visually determined after irradiating a 0.5 mm thick sheet with 5 Mrad using a 1.5 MeV electron beam accelerator. Flexibility (scanto modulus): A 0.5 mm thick sheet was irradiated with 5 Mrad using a 1.5 MeV electron beam accelerator and then tested in accordance with UL224. The judgment is
Conforms to UL224 flexible type criteria.

[Table] [Effects of the Invention] As explained above, according to the present invention, it is possible to obtain a crosslinked molded article having excellent flexibility, transparency, and flame retardancy.

Claims (1)

[Claims] 1. 0.5 to 100 parts by weight of a polyfunctional monomer to 100 parts by weight of a resin component containing 20 to 80% by weight of a polyester thermoplastic elastomer and 80 to 20% by weight of polyvinylidene fluoride.
1. A method for producing an irradiation-crosslinked flame-retardant transparent resin molded article, which comprises molding a resin composition containing 15 parts by weight and crosslinking it by irradiation with ionizing radiation.