JPH07188499A - Production of fluororesin molding - Google Patents

Abstract

PURPOSE:To produce a fluororesin molding improved in heat resistance, mechanical strengths, etc., by previously crosslinking a powdered fluororesin, adding the crosslinked powdered resin as an additive to a fluororesin and molding the resultant mixture into a product. CONSTITUTION:A molding of a fluororesin containing a thermoplastic vinylidene fluoride/hexafluoropropylene copolymer or/and a thermoplastic vinylidene fluoride/hexafluoropropylene/tetrafluoroethylene copolymer is produced from a mixture of the uncrosslinked fluororesin (A) with a crosslinked fluororesin powder (B) obtained by previously crosslinking a powder of the fluororesin composition. The amount of component B added is usually 1-50 pts.wt. per 100 pts.wt. component A. This process is applicable to the production of cables, moldings, and electric wires and is useful in the production of especially heat- shrinking tubes.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The present invention can be applied to various fields such as cables, molded products, electric wires, and cables utilizing the characteristics of fluororesin, and is improved fluororesin molding useful for the production of tubes, particularly heat-shrinkable tubes. The present invention relates to a method for manufacturing a product. Furthermore, the present invention relates to a novel method for producing a fluororesin molded product having remarkably improved heat resistance and mechanical strength.

[0002]

2. Description of the Related Art VdF polymer, VdF-HF
P copolymers and VdF-HFP-TFE copolymers are used for heat-shrinkable tubes and the like by taking advantage of their heat resistance and oil resistance. In the case of a fluororesin, when a large amount of a filler such as polyolefin is blended with the fluororesin, heat resistance and the like are deteriorated, and the blending amount is usually small. Therefore, it is difficult to obtain the mechanical strength, and it is necessary to improve the mechanical strength of the fluororesin.

Therefore, in order to crosslink the fluororesin to obtain mechanical strength and heat resistance, the fluororesin is mixed with a crosslinking aid and molded, and then crosslinked by electron beam irradiation or the like. However, known cross-linking aids such as triallyl isocyanurate, triallyl cyanurate and diallyl phthalate do not have good compatibility with fluororesins, and when a large amount is blended, leaving the molded product before cross-linking for a long time helps The agent bleeds onto the surface of the molded product. Further, when the molded product is processed at a high temperature, the crosslinking aid partially reacts to become a foreign substance, which may be present in the molded product, which is not preferable.

[0004]

As a result of various studies on the above problems, the present invention provides a molded product by preliminarily crosslinking a fluororesin powder and blending it with a fluororesin as a compounding agent. The purpose is to unexpectedly improve heat resistance and mechanical strength.

According to the present invention, a fluororesin molding containing a thermoplastic copolymer of VdF and HFP or / and a thermoplastic copolymer of VdF, HFP and TFE is obtained by pre-crosslinking the fluororesin powder. Provided is a method for producing a fluororesin molded article, which is produced from a mixture of a crosslinked fluororesin powder (B) and the uncrosslinked fluororesin (A). Furthermore, it is also characterized in that the molded article described above has a tube shape. Further, there is provided a method for producing a heat-shrinkable tube, in which the tube obtained as described above is crosslinked with an uncrosslinked fluororesin by electron beam irradiation and then used as a heat-shrinkable tube.

The present invention further includes the following embodiments. The blending amount of (B) with respect to 100 parts by weight of (A) is 1 part by weight or more and 50 parts by weight or less,
A method for producing a fluororesin molded article is provided.

The present invention will be described in detail below. The fluorine resin used in the method of the present invention is mainly VdF and H
Thermoplastic copolymer of FP or VdF, HFP and TFE
The thermoplastic copolymer and the mixture thereof may be used, or a small amount of another fluorine resin compatible with the fluorine resin may be blended, if necessary, to the extent that the performance of the fluorine resin is not impaired. You can

Specifically, the method of the present invention comprises (i) first, a VdF-HFP thermoplastic copolymer, and / or VdF.
-HFP-TFE thermoplastic resin-containing fluororesin powder is pre-crosslinked. Although any crosslinking method can be adopted for the crosslinking, irradiation with ionizing radiation, particularly an electron beam is preferable, and specifically, the irradiation with an electron beam is preferably 1 Mrad or more and 50 Mrad or less. Besides, chemical crosslinking with an organic peroxide such as dicumyl peroxide or 3-bis (t-butylperoxyisopropyl) benzene can be used.

To use the crosslinked fluororesin powder (B) as a filler, the particle size is 50 μm or less,
It is preferably 20 μm or less. (Ii) On the other hand, with respect to 100 parts by weight of a fluororesin (A) containing an uncrosslinked VdF-HFP thermoplastic copolymer or / and a VdF-HFP-TFE thermoplastic copolymer, the above-mentioned crosslinked fluororesin is added. 1 part by weight or more of powder (B) 5
0 parts by weight or less are compounded and molded.

In this case, if the compounding amount of the above-mentioned pre-crosslinked fluororesin powder (B) is less than 1 part by weight, improvement in properties such as heat resistance and mechanical strength cannot be expected, and if it exceeds 50 parts by weight, fluorine is not contained. Molding processing of the resin composition becomes difficult. The pre-crosslinked fluororesin powder (B) has excellent affinity with the non-crosslinked fluororesin (A), the filling effect is recognized, and the properties such as heat resistance and mechanical strength are improved.

The molded article of the fluororesin of the present invention is, if necessary, compounded with various compounding agents in the composition by means such as kneading, processed into molding powder such as pellets, and then provided to various molding means. Is desirable. The fluororesin molded product of the present invention can be used particularly as a tube molded product or a heat shrinkable tube.

(Iii) In order to improve the properties such as heat resistance and mechanical strength of the molded article obtained by the method of the present invention,
Alternatively, in order to obtain a heat-shrinkable tube, it is desirable that the uncrosslinked fluororesin portion of the molded article is subsequently crosslinked by a known electron beam irradiation to form a crosslinked tube. Upon crosslinking the fluororesin molding by the electron beam irradiation, a crosslinking accelerator,
For example, trimethylolpropane trimethacrylate, triallyl cyanurate, triallyl isocyanurate,
A polyfunctional monomer such as triallyl trimellitate may be blended in advance. The compounding amount of the polyfunctional monomer is not particularly limited, but is preferably 0.5 to 10 parts by weight, for example.

The pre-blending of the crosslinking accelerator for the electron beam irradiation may be applied to the production of the pre-crosslinked fluororesin powder (B), if necessary. Specifically, the tube can be made into a heat-shrinkable tube by expanding the diameter of the tube under a heating condition by sending compressed air into the molded article and then fixing the tube rapidly.

The term "heat-shrinkable tube" as used herein means that a tubular molded product whose shape is previously stored by cross-linking is heated to a temperature above the melting point of the tubular molded product to expand the diameter of the tubular molded product and then rapidly cooled. It is obtained by. By heating the heat-shrinkable tube thus produced to a temperature equal to or higher than the melting point, the tube-shaped molded product stored in advance is restored.

Further, the fluororesin molding of the present invention comprises
As long as the object of the present invention is not impaired, usual compounding agents, flame retardants, flame retardant aids, fillers, antioxidants, pigments, if necessary.
Processing aids and the like can be appropriately added. In the case of the present invention, as the filler, metal oxides such as zinc oxide, magnesium oxide, zinc oxide, etc .; metal hydroxides such as calcium hydroxide, magnesium hydroxide, aluminum hydroxide; calcium carbonate, lead carbonate, magnesium carbonate, etc. It is preferable to use a reinforcing inorganic reinforcing agent such as a metal carbonate; silica, talc, clay or the like.

[0016]

EXAMPLES The present invention will be specifically described with reference to Examples.
These do not limit the scope of the invention. The fluororesin powder was previously irradiated with 12 Mrad of an electron beam and used as a compounding agent. 1m by kneading based on the formulation example in Table 1 below
After preparing the m-sheet, electron beam was irradiated at 12 Mrad to measure tensile strength and elongation after heat aging. The results are shown in Table 1.

Although Example 1 and Comparative Example 1 have the same composition, especially in Example 1, by using the crosslinked fluororesin powder, the tensile strength and the elongation after aging at 300 ° C. for 4 hours are large. Examples 2 and 3 are 2 of the fluororesin 2 of the comparative example.
It has improved elongation after aging at 50 ° C for 7 days.

[0018]

[Table 1]

(Note) Fluororesin 1; VdF-HFP-T
FE copolymer kynar9300 (manufactured by Mitsubishi Yuka) Fluororesin 2; VdF-HFP copolymer kynar2800 (manufactured by Mitsubishi Yuka) Crosslinked fluorine powder 1; Powder of fluororesin 1 kynar9301 (manufactured by Mitsubishi Yuka) Crosslinked fluorine powder Body 2: kynar7201 (manufactured by Mitsubishi Yuka)

A tube having an inner diameter of 3 mm and an outer diameter of 3.5 mm was prepared on the basis of the composition of Example 1 and was prepared with an electron beam accelerator.
Irradiated with Mrad. The tube has an inner diameter of 2 at 100 ° C.
The diameter was doubled and rapidly cooled to obtain a heat-shrinkable tube having twice the inner diameter. The heat-shrinkable tube was heated to 100 ° C. to shrink it to the original inner diameter.

[0021]

EFFECTS OF THE INVENTION According to the production method of the present invention, the obtained oil-molded product has improved mechanical strength, heat resistance and the like while maintaining the oil resistance of the fluororesin, and is used as a heat shrinkable tube or the like. it can.

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display area B29K 105: 02 B29L 23:00

Claims (3)

[Claims] 1. A thermoplastic copolymer of vinylidene fluoride (hereinafter abbreviated as VdF) and hexafluoropropylene (hereinafter abbreviated as HFP), and / or VdF and HF.
A molded product of a fluororesin containing a thermoplastic copolymer of P and tetrafluoroethylene (hereinafter abbreviated as TFE) is a crosslinked fluororesin powder (B) obtained by pre-crosslinking the powder of the fluororesin composition with the above-mentioned crosslinked fluororesin powder (B). A method for producing a fluororesin molded article, which comprises producing from a mixture with an uncrosslinked fluororesin (A). 2. A method for manufacturing a tube, wherein the molded product according to claim 1 has a tube shape. 3. A method for producing a heat-shrinkable tube, characterized in that the tube obtained according to claim 1 is crosslinked with an uncrosslinked fluororesin by electron beam irradiation and then used as a heat-shrinkable tube.