JPH09176426A - Fluororesin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a fluororesin compsn. which can be light-colored, has excellent mechanical strengths and low hardness, and does not thermally soften even at 180 deg.C. SOLUTION: This fluororesin compsn. is prepd. by compounding a thermoplastic fluorocopolymer with a silicone rubber in a wt. ratio of (98:2)-(40:60). The fluorocopolymer has a compsn. ratio of vinylidene fluoride, hexafluoropropylene, and tetrafluoroethylene in the area surrounded by four points: 10:35:55, 10:15:75, 55:5:40, and 55:15:30.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluorine-containing resin composition, and in particular, it does not cause a thermal softening phenomenon when used at a high temperature of about 180 ° C., is flexible and has excellent mechanical strength and mechanical extensibility, and has a bright color mixture. The present invention relates to a fluorine-containing resin composition that can be used for a covering material for electric wires, an electric insulating tube, a heat-shrinkable tube, and the like.

[0002]

2. Description of the Related Art The composition ratio of vinylidene fluoride, propylene hexafluoride and tetrafluoroethylene is 10:35:55, 1
The fluorine-containing thermoplastic copolymer (hereinafter abbreviated as THV type fluorine-containing thermoplastic copolymer) within the range surrounded by 4 points of 0:15:75, 55: 5: 40, 55:15:30 is ,
Wonfock Technical Conference held from 29th to 31st July 1994
Cal Conference) 3P P
aul F. It is a new type of fluorinated thermoplastic copolymer announced by Tuckner.

This is a conventional fluorine-containing elastomer having the same composition but different composition ratios (the composition ratio of vinylidene fluoride, propylene hexafluoride and ethylene tetrafluoride is 25: 40: 3).
5, 50:15:35, 75: 25: 0, 40:60:
It has a melting point not found in conventional elastomers, and has a mechanical strength of It is three times as high, and a filler that acts as a reinforcement is mixed in,
Recently, it has attracted attention as a material that can be used without cross-linking.

[0004] The technical data prepared by 3M Company, which was created based on the content of the conference, states that THV fluorine-containing thermoplastic copolymers can be crosslinked by irradiation with electron beams. In some cases, heat-shrinkable tubes using electron beam irradiation crosslinking are also made.

However, even if the THV fluorine-containing thermoplastic copolymer is irradiated and crosslinked by an electron beam or the like alone, the THV fluorine-containing thermoplastic copolymer has a low crosslinking efficiency. When the molded product of (1) is placed in an oven at 180 ° C, the molded product is immediately softened by heat and cannot retain its original shape.

On the other hand, in order to improve the crosslinking efficiency of such a polymer having a poor crosslinking efficiency, a method of adding a polyfunctional monomer is generally shown.

However, in general, the polyfunctional monomer, which is usually in the form of an oil, is most effective for the irradiation crosslinking of these THV fluorine-containing thermoplastic copolymers, and the composition is less contaminated. However, these oil-like polyfunctional monomers have very poor dispersion and kneading properties for resins such as THV fluorine-containing thermoplastic elastomers and rubber substances, and the oil and resin slip in the kneading machine to cause kneading. become unable. In order to improve the kneading property, there are solid substances as an example of the special polyfunctional monomer, but these have a low effect of increasing the crosslinking efficiency of the THV fluorine-containing thermoplastic copolymer, and generally have a low contamination property. Since the resin or rubber is strongly discolored into yellow or purple, there arises a problem that it cannot be used in a bright color compound.

Therefore, usually, when using a polyfunctional monomer, the minimum necessary amount of filler is blended and kneaded.

Generally, in order to prevent thermal softening of the THV type fluorine-containing thermoplastic copolymer molding at 180 ° C., it is necessary to mix the polyfunctional monomer and the filler in a well-balanced manner, but it is intended to enhance the crosslinking efficiency. As the polyfunctional monomer is increased, the kneading property is significantly reduced, and conversely, when the filler amount is increased, thermal softening is suppressed, but the mechanical elongation of the molded product is drastically reduced and the hardness of the molded product is also decreased. Will rise significantly. Therefore, it has been impossible to improve the crosslinking efficiency without increasing the hardness of the THV fluorine-containing thermoplastic copolymer molded article.

On the other hand, Japanese Patent Publication No. 6-95444 discloses that
A heat-resistant oil-resistant insulated electric wire formed by coating a conductor with an insulating layer in which silicone rubber is mixed with vinylidene fluoride-based fluororubber is described, but it is generally shown as a material that can be used for the insulating layer shown in this publication. The vinylidene fluoride-based fluororubber is an ordinary vinylidene fluoride-based fluororubber, and is completely different from the THV-based fluorine-containing thermoplastic copolymer shown in the present invention in that the melting point is not recognized. is there.

Further, when comparing the mechanical strength and physical properties such as tearability of the molded products, the characteristic values of the two are completely different, and when ordinary vinylidene fluoride fluororubber is used, the mechanical strength is The improvement in tear strength is slight.

[0012]

SUMMARY OF THE INVENTION The object of the present invention is to solve the problems of the prior art and to enable bright color compounding.
Excellent mechanical strength and extensibility, low hardness and 180 ° C
It is intended to provide a fluorine-containing resin composition that does not cause a thermal softening phenomenon even under use conditions.

[0013]

As a result of various studies to achieve the above object, the present inventor has found that a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer having a specific composition ratio and a silicone. Inspired by mixing with rubber,
The present invention has been completed.

That is, in the present invention, the composition ratio of vinylidene fluoride, propylene hexafluoride and ethylene tetrafluoride is 10: 3.
5:55, 10:15:75, 55: 5: 40, 55:
98: 2 by weight ratio of the fluorine-containing thermoplastic copolymer and the silicone rubber within the range surrounded by 4 points of 15:30.
It is the fluorine-containing resin composition characterized by mix | blending in the range of 40:60.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION As the silicone rubber used in the present invention, fluorosilicone rubber, methylphenyl silicone rubber, methylphenyl vinyl silicone rubber,
One or more silicone rubbers selected from the group of dimethyl silicone rubber and methyl vinyl silicone rubber may be blended and used. The silicone rubber may be in the form of gum, which is a raw rubber, or a reinforcing agent for the raw rubber. It is also possible to use a gum base having the above additions, a filler and the like added to the gum base, and a usual commercially available U-stock.

Further, as described above, the fluorine-containing thermoplastic copolymer used in the present invention has a conventional vinylidene fluoride-propylene hexafluoride copolymer and vinylidene fluoride depending on the composition ratio and the presence or absence of a melting point. It is a completely different polymer from fluororubber copolymers such as propylene hexafluoride-tetrafluoroethylene copolymer. As the fluorine-containing thermoplastic copolymer used in the present invention, THV polymer [manufactured by 3M] can be preferably used.

In the fluorine-containing resin composition of the present invention,
The fluorine-containing thermoplastic copolymer and silicone rubber,
It is necessary to blend in a weight ratio within the range of 98: 2 to 40:60.

If the weight ratio of the fluorine-containing thermoplastic copolymer to the silicone rubber is less than 98: 2, in order to maintain the degree of crosslinking sufficient to prevent the softening of the molded product, the polyfunctional monomer should be 5%. More than parts by weight must be added, and as a result, the amount of filler must be increased, which not only increases the hardness of the molded product but also significantly reduces the mechanical extensibility.

On the other hand, if the silicone rubber is blended in excess of 40:60, not only the mechanical strength will be significantly lowered, but also the tearability of the molded product will be extremely poor. The most preferable mixing ratio is 95: 5 or more and 75:25 or less.

Generally, in order to enhance the compatibility of these compositions, an ethylene polymer may be mixed in to supplement the compatibility.

Examples of the ethylene-based polymer include homopolymers or copolymers of olefins such as ethylene, propylene, butene, octene, dicyclopentadiene and ethylidene norbornene. Examples of the copolymers include Is the above polyolefins and vinyl acetate, ethyl acrylate, methyl acrylate, ethyl acrylate,
Examples thereof include copolymers with ethyl methacrylate and the like. In particular, an ethylene-vinyl acetate copolymer having a melting point of 100 ° C. or lower is preferably used. This ethylene polymer usually has no melting point or a melting point of 100.
Most preferably, the temperature is not higher than ° C.

The amount of the ethylene-based polymer is usually 10 parts by weight or less, preferably 5 parts by weight or less, since mechanical strength and heat resistance are deteriorated when a large amount is blended.

Similarly, an ordinary fluororubber copolymer may be mixed as an agent having the effect of enhancing the compatibility of these compositions. In this case, the compounding amount of the fluororubber is preferably 20 parts by weight or less with respect to 100 parts by weight of the mixture of the fluorine-containing thermoplastic copolymer and the silicone rubber.

If the blending amount of the fluororubber copolymer exceeds 20 parts by weight, the tearability is remarkably deteriorated, which is not preferable.

Further, examples of the cross-linking aid used to achieve the improvement in the cross-linking degree include allyl type compounds, sulfur, organic amines, maleimides, methacrylates, divinyl compounds, polybutadiene and the like. The allyl type compounds represented by nurate and triallyl cyanurate are most preferable, and the compounding amount thereof is usually 2 to 10 parts by weight, preferably 3 to 5 parts by weight from the viewpoint of both the improvement of the crosslinking degree and the saturation of the effect.

An inorganic filler is usually used in order to facilitate the kneading of the crosslinking aid with the resin and rubber components during extrusion molding. Examples of the inorganic filler include talc, clay, silicic acid anhydride, calcium carbonate, calcium silicate, and the like, but silicic acid anhydride, calcium carbonate, calcium silicate, and talc are preferable because they do not significantly lower the tensile properties even if they are mixed in a large amount. .

In particular, calcium carbonate or talc having a particle size in the range of 1 to 3 μm is effective in suppressing foaming during extrusion molding, preventing sagging of the tube during tube molding, and improving inner surface tackiness.

The blending amount of the inorganic filler is remarkably lowered in the mechanical elongation of the composition when it is blended in a large amount, so that the blending amount of the inorganic filler is preferably the minimum amount required for kneading the resin and the rubber component and the polyfunctional monomer. Usually, about 10 to 20 parts by weight is preferable.

In addition to the above-mentioned components, addition of rare earth oxides for improving the crosslinking efficiency, stabilizers, pigments, antioxidants,
Various additives such as lubricants can be blended.

The fluorine-containing resin composition of the present invention is generally crosslinked using chemical crosslinking or ionizing radiation. Examples of the ionizing radiation include X-rays, γ-rays, proton rays, deuteron rays, neutron rays, α-rays and β-rays, but γ-rays or β-rays are preferably used.

Further, chemical crosslinking can be generally carried out by lowering the molding temperature, but since the vulcanization time becomes very long and the moldability is poor, it is usually preferable to carry out the crosslinking by ionizing radiation.

[0032]

The present invention will be described in detail below with reference to examples.

[0033]

Examples 1 to 6 and Comparative Examples 1 to 6 The total weight was determined according to the specific gravity so that the total volume of the composition kneaded was 2.4 liters, and the materials shown in Tables 1 and 2 were used. A 3 liter pressure type kneader preheated to 160 ° C. was charged according to the compounding ratio. At this time, the amount of the filler was set to the minimum number of parts that enables kneader kneading. Remove the pressure lid and set the rotation speed of one of the pair of rotary blades to 29 rpm and the rotation speed of the other to 43 rpm.
Kneading was started at rpm. Beginning with polymer only 2
After kneading for 5 minutes, all compounding ingredients were added and kneading was carried out for 5 minutes. Then, the kneaded product was discharged, and the sheet was shaped by a roll mill.

This kneaded product was a 40 mm extruder (L / D = L / D = 180 ° C. for die temperature, 180 ° C. for head temperature, 170 ° C. for cylinder 1 and 130 ° C. for cylinder 2).
22) was used to extrude a tube having an inner diameter of 2.5 mm and a wall thickness of 0.5 mm.

Next, Co with a holding capacity of 1 million curies
^{A 60-} ray source was used to irradiate 100 kGy of γ-rays for crosslinking.

The tensile strength, elongation, thermal softening property, hardness and tearability of the crosslinked tube were measured as described above. These measuring methods are as follows.

(1) The initial tensile strength and the initial elongation are JIS
According to C 3005 (Insulator tensile test), the tube shape was measured. Here, initial tensile strength 15MP
The general requirement value is a or more and an initial elongation rate of 200% or more.

(2) The heat softening property of the crosslinked tube is 10c.
Cut it to a length of about 1 m and place it flat in an oven at 180 ℃ 1
Leave for 5 minutes. JIS C 2133 (test method for electrically insulating tubes) 6. According to the dimensions, the minimum outer diameter value of the initial cross-linked tube and the cross-linked tube after being left in the oven is measured using an optical contour projector, and if the value of the number 1 is 80% or more, it is ○, and if it is less than 80%, it is ×. And

[0039]

[Equation 1]

(3) As for hardness, according to JIS K 6253, a crosslinked tube was torn in the longitudinal direction, three such test pieces were stacked to form a micro test piece, and a Wallace type hardness tester (type D durometer push needle) was used. )Using,
The type D durometer hardness was directly read. Here, the general requirement value is 50 or less.

(4) Tearability of the crosslinked tube is 10 cm.
Cut into lengths and make a 20 mm long cut symmetrically with respect to the concentric circle of this cross section using a sharp razor etc. according to JIS C 6252, and attach the cut tubes to the upper clamp and lower clamp of the tensile tester, respectively. Then, the tensile tester is pulled at a speed of 200 mm / min, and the maximum load at that time is obtained.

The results are shown in Tables 1 and 2.

[0043]

[Table 1]

[0044]

[Table 2]

As is clear from the results shown in Tables 1 and 2, Examples 1 to 6 are excellent in initial tensile strength, initial elongation and thermal softening property, less in tearability, and less than conventional ones. It was possible to maintain the hardness so that the bending flexibility did not change so much.

On the other hand, when the silicone rubber is not blended (Comparative Example 1), the heat softening property is not improved. Even when the inorganic filler and the polyfunctional monomer are blended (Comparative Example 2), the heat softening property is improved. Not improved.

If the silicone rubber content is too small, a minimum of 5 is required to satisfy the heat softening property.
It is necessary to add parts by weight of the polyfunctional monomer, and by adding the minimum amount of filler necessary for kneading the mixture, the hardness becomes high (Comparative Example 3). When it is reduced, the heat softening property is poor (Comparative Example 4).

On the other hand, when the blending amount of the silicone rubber is too large (Comparative Examples 5 and 6), the mechanical strength such as initial tensile strength and tearability is remarkably lowered.

[0049]

EFFECTS OF THE INVENTION According to the fluorine-containing resin composition of the present invention, a bright color can be blended, the mechanical strength, the mechanical extensibility and the tearability are excellent, and the bendability is the same as that of the conventional product, and even at a high temperature. It is possible to obtain a molded product that does not undergo thermal softening.

[Brief description of the drawings]

FIG. 1 is a ternary composition diagram showing the composition ratio of a fluorine-containing thermoplastic copolymer used in the present invention and the composition ratio of a conventional fluororubber copolymer.

[Explanation of symbols]

 VDF Vinylidene fluoride HFP Hexafluoropropylene TFE Tetrafluoroethylene

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display area // (C08F 214/26 214: 28)

Claims (1)

[Claims] 1. The composition ratio of vinylidene fluoride, propylene hexafluoride and ethylene tetrafluoride is 10:35:55, 1
98: 2 to 40: by weight ratio of the fluorine-containing thermoplastic copolymer and silicone rubber within the range surrounded by 4 points of 0:15:75, 55: 5: 40, 55:15:30. 6
A fluorine-containing resin composition characterized by being blended within a range of 0.