JPH06212044A - Resin composition - Google Patents

Abstract

PURPOSE:To obtain a resin composition consisting of polyvinylidene fluoride and a copolymer of vinylidene fluoride and tetrafluoroethylene, etc., and a copolymer or ethylene and an acetic acid monomer of a specific ratio, excellent in transparency and useful for thermally shrinkable tube, etc. CONSTITUTION:This resin composition is obtained by blending (A) polyvinylidene fluoride or a copolymer of vinylidene fluoride and at least one monomer of tetrafluoroetylene and hexafluoropropylene (e.g. vinylidene fluoride- tetrafluoroethylene copolymer) with (B) a copolymer of ethylene and preferably >=70wt.% vinyl acetate, preferably in a weight ratio of the components A/ B of (90/10) to (55/45).

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The resin composition of the present invention can be applied to various fields such as films, molded products, electric wires, cables, etc., which make use of the characteristics of fluororesin, which is required to be transparent. The present invention relates to the improvement of the constituent materials.

[0002]

2. Description of the Related Art Copolymers containing vinylidene fluoride, tetrafluoroethylene, and hexafluoropropylene monomers have high material costs, but their heat resistance
Oil resistance, weather resistance, non-contamination, etc. are used for film,
Widely used for electric wires and cables.

For example, heat-shrinkable tubes made of polyvinylidene fluoride are known. However, these tubes are hard, and those obtained by improving the same include vinylidene fluoride, tetrafluoroethylene, and hexafluoropropylene monomers. Polymers are known.

Polymethylmethacrylate (hereinafter referred to as PMMA) is used as a resin to be added to polyvinylidene fluoride.
(Abbreviated as)) is known. This is an example of trying to improve the transparency of polyvinylidene fluoride.
MA has a low elongation of about 10%, and when molded into a tube or the like, the elongation is insufficient.

Japanese Patent Publication No. 4-73459 describes a blend of a thermoplastic fluorine-containing resin and a modified ethylene polymer obtained by graft-polymerizing an alkyl acrylate onto an ethylene polymer.

[0006] This formulation does not take transparency into consideration, and shows good compatibility from the dispersibility and elongation at break point, and is not suitable for applications requiring transparency.

[0007]

Means for Solving the Problems As a result of various studies on the above problems, the present inventor has found that as a resin to be blended with a polyvinylidene fluoride resin, a copolymer of ethylene and vinyl acetate having a specific vinyl acetate content. It has been found that the use of the compound (1) improves the elongation while maintaining the transparency of the polyvinylidene fluoride resin, thus completing the present invention.

That is, the present invention is: (A) a copolymer of polyvinylidene fluoride or vinylidene fluoride and at least one monomer of tetrafluoroethylene or hexafluoropropylene, and (B) a copolymer of ethylene and vinyl acetate. The copolymer of (B) has a vinyl acetate monomer content of 60% by weight or more, and the weight ratio of the mixture (A /
A resin composition in which B) is 95/5 to 50/50 is provided. Also,

There is also provided a tube comprising the composition according to claim 1, and further provided is a heat-shrink tube in which the tube according to claim 1 has a cross-linking bond.

The present invention will be described in detail below. In the present invention, the fluororesin comprising (A) polyvinylidene fluoride or a copolymer of vinylidene fluoride and at least one monomer of tetrafluoroethylene and hexafluoropropylene has a weather resistance higher than that of polyolefin such as polyethylene. Excellent in resistance to dirt, heat resistance and oil resistance. Taking advantage of such characteristics, it is necessary to directly see the object to be coated in a tube used as various films, molded products, electric wires, and tubes, for example, a film, a packaging material, or a tube used for protecting electric wire connection portions. Transparency is required for such applications.

The copolymer of vinylidene fluoride and at least one monomer of tetrafluoroethylene or hexafluoropropylene is typically a vinylidene fluoride-tetrafluoroethylene copolymer or vinylidene fluoride-hexafluoro. Examples of the propylene copolymer, vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene terpolymer, vinylidene halide or vinylidene halide other than fluorine can be further included in the vinylidene fluoride copolymer. Body, ethylene, butene-1, (meth) acrylic acid or a monomer such as an alkyl ester thereof may be copolymerized.

The weight ratio (A / B) of the resin composition useful for utilizing the above characteristics of the fluororesin is 95/5 to 5/5.
50/50, preferably 90/10 to 55/45. If the blending amount of the fluororesin (A) exceeds 95% by weight, the amount of the blended ethylene-vinyl acetate copolymer (B) is small, resulting in lack of elongation at break and limited range of use. Further, the blending amount of the fluororesin (A) is 50
If it is less than the above, the original characteristics of the fluororesin cannot be utilized.

In order to realize the transparency of the fluororesin (A), which is a feature of the present invention, a copolymer of ethylene and vinyl acetate (hereinafter abbreviated as EVA) (B) contains vinyl acetate. The amount is 60% by weight or more, preferably 70% by weight or more. The vinyl acetate content in the EVA is 60
If it is less than wt%, the transparency of the fluororesin (A) cannot be sufficiently exhibited.

The copolymer of ethylene and vinyl acetate includes
Typically, a copolymer of ethylene and vinyl acetate can be mentioned, but other vinyl monomers such as vinyl chloride, (meth) acrylic acid, its ester, maleic acid, maleic anhydride, etc. Those which are copolymerized or graft-copolymerized, or partially or completely saponified products of the above-mentioned copolymer of ethylene and vinyl acetate are included.

The resin composition of the present invention is prepared by mixing various compounding agents into the base resin containing (A) and (B) by a means such as kneading, if necessary, and processing them into molding powder such as pellets. , Molded by various molding means.

Specifically, the resin composition of the present invention is made into various molded articles such as tubes and heat shrinkable tubes by known molding means such as extrusion coating, extrusion molding, injection molding and press molding. The resin composition of the present invention can be used particularly as a tube molded product or a heat shrinkable tube.

The molded article obtained by the present invention is crosslinked by irradiation with known ionizing radiation (electron beam, etc.) in order to improve heat resistance, mechanical strength, etc., or a heat shrinkable tube. Then, make a crosslinked tube.

In this case, acrylic monomers such as triallyl cyanurate, triallyl isocyanurate and trimethylolpropane triacrylate, and polyfunctional monomers such as diallyl phthalate can be used as the crosslinking promoting monomer. In order to carry out the crosslinking efficiently, the polyfunctional monomer may be previously mixed in the resin composition in an amount of 1 part by weight or more and 10 parts by weight or less.

In addition to irradiation with ionizing radiation, thermal crosslinking after the blending of an organic peroxide such as dicumyl peroxide or 3-bis (t-butylperoxyisopropyl) benzene is also possible for the above crosslinking. is there.

Further, the tube is crosslinked by irradiating it with ionizing radiation, and then the tube is expanded and cooled and fixed by a method such as sending compressed air into the molded article under heating conditions. Can also be

Here, the heat-shrinkable tube is obtained by heating a tube-shaped material whose shape is previously stored by cross-linking to a temperature equal to or higher than the melting point of the tube-shaped material, expanding the tube-shaped material and rapidly cooling it. Is. The heat-shrinkable tube produced in this manner is heated to a temperature equal to or higher than the melting point to restore the tube-shaped object stored in advance.

Further, the resin composition of the present invention may contain a conventional compounding agent, if necessary, unless the object of the present invention is impaired.
Flame retardants, flame retardants such as antimony trioxide, organic fillers, inorganic fillers, antioxidants, light stabilizers, processing aids, carbon black, pigments and other polymers such as ethylenic copolymers. Can be blended.

Also, the resin composition of the present invention is coated on the outer periphery of a multi-core twisted insulated wire of a single core or a plurality of insulated wires made of a conductor such as copper by a molding means such as extrusion coating, and further ionizing radiation. It is also possible to irradiate and crosslink to obtain an insulated cable.

[0024]

The present invention is illustrated by the following examples, which do not limit the scope of the invention. (Examples 1 to 6 and Comparative Examples 1 to 4) Sheets having a thickness of 0.5 mm were prepared after kneading with a roll based on the formulations of Examples and Comparative Examples. This sheet was irradiated with an electron beam at 6 Mrad. The results are shown in Table 1 below.

[0025]

[Table 1]

○: transparent, ×: cloudy opaque Note) Fluorine 1: Polyvinylidene fluoride DSC Melting point; 162 ° C., MI; 0.02 (230 ° C., 2.16 kgf) Fluorine 2: Vinylidene fluoride-hexafluoropropylene copolymer ( Vinylidene fluoride content: about 80
Wt%) DSC melting point; 148 ° C, MI; 0.2 (230 ° C, 2.16 kgf) Fluorine 3: vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer (vinylidene fluoride content; about 75% by weight) DSC melting point 90 ℃,

EVA1: Vinyl acetate content 82% by weight, Mooney viscosity ML _{1 + 4} ; 11 (100 ° C) EVA2: Vinyl acetate content 70% by weight, Mooney viscosity M
L _{1 + 4} ; 13 (100 ℃) EVA3: vinyl acetate content 45% by weight, Mitsui Polychemicals EVAflex EV45LX

Modified ethylene 1: methacrylic acid graft E
VA (Dainippon Ink and Chemicals HP-30) Modified ethylene 2: Mitsubishi Yuka VMX

Examples 1 to 6 retained the transparency of the fluororesin and were excellent in compatibility, while Comparative Examples 1 to 4 were clouded and compatible, but this is not sufficient. The elongations of the resin compositions of Examples 1 to 6 were all 100% or more, which was extremely good.

(Example 7) A tube having an inner diameter of 3 mm and an outer diameter of 3.5 mm was prepared based on the formulation of Example 1 and irradiated with 3 Mrad by an electron beam accelerator. This tube is 180 ℃
The inner diameter was doubled below and rapidly cooled to obtain a heat-shrinkable tube having an inner diameter twice. The appearance was smooth and transparent. The tube was heated at 180 ° C. to shrink it to the original inner diameter.

(Comparative Example 5) A tube was prepared in the same manner as in Example 1 based on the formulation of Comparative Example 1, but the tube surface was significantly roughened and clouded, resulting in poor compatibility.

[0032]

EFFECTS OF THE INVENTION The resin composition of the present invention can provide an inexpensive fluororesin while maintaining the transparency of vinylidene fluoride resin, and is used for heat shrinkable tubes and the like.

Claims (3)

[Claims] 1. (A) polyvinylidene fluoride or vinylidene fluoride and tetrafluoroethylene,
A mixture of hexafluoropropylene with at least one monomer and (B) a copolymer containing ethylene and vinyl acetate, wherein the vinyl acetate monomer content in the copolymer (B) is 60.
Weight% or more, the weight ratio (A / B) of the admixture is 95/5 to 5
The resin composition is 0/50. 2. A tube, characterized in that it comprises the composition according to claim 1. 3. A heat-shrinkable tube, wherein the tube according to claim 2 is a heat-shrinkable tube having a cross-linking bond.