JPH0959469A - Fluororesin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a fluororesin compsn. which can be light-colored, is excellent in mechanical strengths and elongation, has a low hardness, and does not undergo thermal softening even at 180 deg.C. SOLUTION: This compsn. is prepd. by compounding 100 pts.wt. thermoplastic fluorocopolymer with 2 pts.wt. or higher but lower than 20 pts.wt. fluorocopolymer rubber. The thermoplastic fluorocopolymer has a compsn. ratio of vinylidene fluoride, hexafluoropropylene, and tetrafluoroethylene within a range determined by four points represeted by (10:30:55), (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 wire covering material, 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 ,
Wonfok Technical Conference held 29-31 July 1994
al Conference), 3M company Pa
ul F Tuckner is a new type of fluorine-containing thermoplastic elastomer.

This is because conventional fluorine-containing elastomers (vinylidene fluoride, propylene hexafluoride, and ethylene tetrafluoride having the same composition but different composition ratios have a composition ratio of 25: 4).
0:35, 50:15:35, 75: 25: 0, 40:
It has a melting point which is not found in conventional elastomers, and its mechanical strength is the same as that of conventional elastomers. It is as high as 2 to 3 times, and has recently attracted attention as a material that can be used without mixing a filler serving as a reinforcing material and 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. There is also a heat-shrinkable tube partially made by electron beam irradiation crosslinking.

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 No. 1 is placed in an oven at 180 ° C., the molded product is instantly softened and the original shape cannot be maintained. On the other hand, a method of adding a polyfunctional monomer is generally shown as a method for increasing the crosslinking efficiency of such a polymer having poor crosslinking efficiency.

However, this polyfunctional monomer is
It is usually oily and has very poor dispersion and kneading properties with respect to resins such as THV fluorine-containing thermoplastic elastomers and rubber substances, so that the oil and the resin will slip in the kneading machine and cannot be kneaded. In addition, there are solid substances as an example of special polyfunctional monomers, but while solid substances are easy to knead, these polyfunctional monomers are generally highly contaminated and give a resin or rubber to yellow or purple. Therefore, there arises a problem that it cannot be used in a bright color mixture.

Therefore, in general, when using a polyfunctional monomer, it is usual to mix and knead the minimum necessary amount of filler. Generally, in order to prevent the 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 in order to improve the crosslinking efficiency, When the number of functional monomer parts is increased, the kneading property is significantly reduced, and on the contrary, when the filler amount is increased, softening is suppressed, but the mechanical elongation of the molded product is sharply reduced and the hardness of the molded product is increased. The problem arises.

[0008]

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 to provide a fluorine-containing resin composition that does not cause a softening phenomenon even under use conditions.

[0009]

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

That is, according to 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:
A fluororesin composition in which 2 parts by weight or more and less than 20 parts by weight of a fluororubber copolymer is mixed with 100 parts by weight of a fluorine-containing thermoplastic copolymer within a range surrounded by 4 points of 15:30. .

The fluororubber copolymer used in the present invention is a tetrafluoroethylene-α-olefin copolymer such as a tetrafluoroethylene-propylene-based copolymer,
Vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer, vinylidene fluoride-perfluoroethylene copolymer and the like can be mentioned, but among these, TH
It is preferable to use a tetrafluoroethylene-propylene-based copolymer that has excellent compatibility with the V-based fluorine-containing thermoplastic copolymer, has a high softening-preventing effect even when added in a small amount, and has a small increase in hardness.

In particular, when a tetrafluoroethylene-propylene-based copolymer is used, there is no particular limitation on the number average molecular weight when light-colored compounding is not required, but when light-colored compounding is required. It is preferable to use a high molecular weight copolymer having a number average molecular weight of 100,000 or more.

Generally, these fluororubber copolymers may be used alone or in combination of two or more.

Further, as described above, the fluorine-containing thermoplastic copolymer used in the present invention has a conventional vinylidene fluoride-hexafluoropropylene 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,
With respect to 100 parts by weight of the above-mentioned fluorine-containing thermoplastic copolymer,
It is necessary to blend the fluororubber copolymer in an amount of 2 parts by weight or more and less than 20 parts by weight. When the content of the fluororubber copolymer is less than 2 parts by weight, the polyfunctional monomer may be added in an amount of 5 in order to maintain a sufficient degree of crosslinking to prevent softening of the molded product.
More than parts by weight must be blended, and as a result, the amount of filler must be increased, resulting in increased hardness of the molded product and loss of extensibility.

On the contrary, if 20 parts by weight or more of the fluororubber copolymer is blended, the mechanical strength will decrease. Further, the preferable blending amount is 5 to 15 parts by weight.

Further, in order to carry out a bright color compounding, it is preferable to use a tetrafluoroethylene-propylene copolymer having a number average molecular weight of 100,000 or more. Generally, this compound is a fluorine-containing thermoplastic copolymer. Since the plasticity with the coalescence is poor, an ethylene-based polymer may be mixed to supplement the plasticity.

Examples of the ethylene-based polymer include homopolymers or copolymers of olefins such as ethylene, propylene, butene, octene, dicyclopentadiene, ethylidene norbornene, and the like. Is the above polyolefins and vinyl acetate,
Examples thereof include copolymers with ethyl acrylate, methyl acrylate, ethyl methacrylate and the like. In particular, the melting point is 10
An ethylene-vinyl acetate copolymer having a temperature of 0 ° C. or lower is used. This ethylene polymer usually has no melting point or preferably has a melting point of 100 ° C. or lower.

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

Further, examples of the cross-linking aid used to achieve the improvement of 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.

Further, an inorganic filler is used in order to facilitate the kneading of the crosslinking aid and the resin and rubber components at the time of extrusion molding. As the inorganic filler, talc, clay,
Examples thereof include anhydrous silicic acid, calcium carbonate, calcium silicate, etc., but anhydrous silicic acid, calcium carbonate, calcium silicate,
Talc is preferred because it does not significantly deteriorate the tensile properties even if it is blended in a large amount.

Particularly, 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 amount of the inorganic filler to be added is preferably the minimum amount required for kneading the resin and the rubber component and the polyfunctional monomer, since the elongation of the composition is remarkably reduced when the amount is large. About 10 to 15 parts by weight is preferable.

Further, 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.

On the other hand, the fluorine-containing resin composition of the present invention is generally crosslinked using chemical crosslinking or ionizing radiation. Ionizing radiation includes X-rays, γ-rays, proton rays, deuteron rays,
Although neutron rays, α rays, β rays and the like can be mentioned, γ rays or β rays are preferably used. Further, chemical crosslinking can generally be performed by lowering the molding temperature, but since vulcanization time becomes very long and moldability is poor, it is generally preferable to carry out crosslinking by ionizing radiation.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail by way of examples. "Examples 1 to 7 and Comparative Examples 1 to 7" 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, set the rotation speed of one of the pair of rotary blades to 29 rpm,
Kneading was started at the other rotation speed of 43 rpm. First, the polymer alone was kneaded for 2 minutes, then all the compounding ingredients were added and kneaded for 5 minutes. Then, the kneaded product was discharged, and the sheet was shaped by a roll mill.

The 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 Curie
^{A 60-} ray source was used to irradiate 100 KGy of γ-rays for crosslinking.

With respect to the crosslinked tube as described above, the tensile strength, elongation rate, heat softening resistance and hardness were measured. 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. Initial tensile strength 20MPa
As described above, the initial elongation rate of 250% or more is a generally required value.

(2) The heat softening resistance of the crosslinked tube is 10
Cut it to a length of about cm, place it flat in an oven at 180 ° C and leave it for 15 minutes. Based on JIS C 2133 (Testing method for electrical insulation tube) 6 dimensions, the minimum outer diameter value of the initial cross-linking tube and the cross-linking tube after being left in the oven was measured using an optical contour projector,

[Equation 1] If the value is 80% or more, it is evaluated as ◯, and if less than 80%, it is evaluated as x.

(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 prepare a micro test piece, and a Wallace type hardness tester (type D durometer push needle) was used. ) Was used to measure the type D durometer hardness by directly reading it.
Here, the general requirement value is 50 or less.

The results are shown in Tables 1 and 2.

[Table 1]

[Table 2] As is clear from the results shown in Tables 1 and 2, Examples 1 to 6
Was excellent in initial tensile strength, elongation, and heat softening resistance, and could be maintained at a hardness such that bending flexibility was not so different from conventional ones.

On the other hand, when the inorganic filler and the polyfunctional monomer are not blended (Comparative Example 1), the heat softening resistance is not improved, the fluororubber copolymer is not blended, and the inorganic filler and the polyfunctional monomer are not blended. When only the monomer is blended (Comparative Example 2), the hardness is high and it is very difficult to bend.

When the amount of the fluororubber copolymer is too small, a minimum of 5 parts by weight of a polyfunctional monomer is necessary to satisfy the heat softening resistance, and the kneading is necessary. When the amount of the inorganic filler is increased, the hardness becomes too high (Comparative Example 3), and conversely, when the amount of the multifunctional monomer is decreased, the heat softening resistance is deteriorated. (Comparative example 4)

On the other hand, when the blending amount of the fluororubber copolymer is too large (Comparative Examples 5, 6 and 7), the initial tensile strength is largely reduced and the mechanical properties are insufficient.

[0037]

EFFECTS OF THE INVENTION According to the fluorine-containing resin composition of the present invention, a bright color can be compounded, mechanical strength and extensibility are excellent, bendability is the same as that of conventional products, and thermal softening occurs even under high temperature use. It is possible to obtain a non-molded product.

[Brief description of drawings]

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

[Explanation of symbols]

 VDF Vinylidene fluoride HFP Hexafluoropropylene TFE Tetrafluoroethylene

Claims (3)

[Claims] 1. The composition ratio of vinylidene fluoride, propylene hexafluoride and ethylene tetrafluoride is 10:35:55, 1
2 parts by weight of a fluororubber copolymer based on 100 parts by weight of a fluorine-containing thermoplastic copolymer within a range surrounded by 4 points of 0:15:75, 55: 5: 40, 55:15:30. A fluorine-containing resin composition characterized by being blended in an amount of less than 20 parts by weight. 2. The fluororesin composition according to claim 1, wherein the fluororubber copolymer is a tetrafluoroethylene-propylene-based copolymer. 3. The fluororesin composition according to claim 2, wherein the tetrafluoroethylene-propylene-based copolymer has a number average molecular weight of 100,000 or more.