JPH09176425A - 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 up to 40 pts.wt. compsn. comprising a crystalline fluororesin and/or a vinylidene fluoride- fluoroolefin copolymer into 100 pts.wt. compsn. comprising 2-60wt.% fluororubber copolymer and 98-40wt.% thermoplastic fluorocopolymer of which the compsn. ratio of vinylidene fluoride, hexafluoropropylene, and tetrafluoroethylene is 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]

TECHNICAL FIELD 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. The present invention relates to a fluorine-containing resin composition that can be used for a wire coating material, an electric insulating tube, a heat-shrinkable tube, and the like that can be compounded.

[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. or higher, the molded product is immediately softened by heat, and the original shape cannot be retained.

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

However, among these polyfunctional monomers, only oily ones are usually effective at the time of irradiation cross-linking in the bright color blending of the THV fluorine-containing thermoplastic copolymer, and the composition is less polluted. However, these oily polyfunctional monomers usually have very poor dispersibility and kneadability when kneading resins such as THV fluorine-containing thermoplastic elastomers and rubber substances, and therefore, they are very poor in the kneader. The oil and resin slip and cannot be kneaded.

In order to improve the kneading property, there are solid substances as examples of special polyfunctional monomers.
There is a problem that the effect of increasing the crosslinking efficiency of the HV-based fluorine-containing thermoplastic copolymer is low, and generally, the resin or rubber is discolored to yellow or purple due to its strong staining property, and it cannot be used in a bright color compound.

Therefore, when using a polyfunctional monomer in a light color compound, it is usually necessary to use an oily polyfunctional monomer and to mix a minimum required amount of a filler.

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 number of polyfunctional monomers is increased, the kneading property is significantly reduced, and on the contrary, when the amount of the filler is increased, thermal softening is suppressed, but the mechanical elongation of the molded product is sharply reduced and the hardness of the molded product is reduced. It rises significantly.

As described above, it was impossible to improve the crosslinking efficiency without increasing the hardness of the THV fluorine-containing thermoplastic copolymer molding.

On the other hand, Japanese Patent Publication No. 2-17341 discloses that
Heat-shrinkable tubes composed of a composition of a tetrafluoroethylene-propylene copolymer and a vinylidene fluoride-fluoroolefin copolymer have been proposed, but these compositions are poor in mechanical strength and have high hardness and bending. hard.

[0013]

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.

[0014]

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 on the idea that a crystalline fluororesin or a vinylidene fluoride-fluoroolefin copolymer is further mixed with a mixture with a rubber copolymer.

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:
The weight ratio of the fluorine-containing thermoplastic copolymer and the fluororubber copolymer within the range surrounded by the four points of 15:30 is 9.
Composition 100 formulated within the range of 8: 2 to 40:60
A fluorine-containing resin composition comprising 40 parts by weight or less of a crystalline fluorine resin and / or a vinylidene fluoride-fluoroolefin copolymer with respect to parts by weight.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The fluororubber copolymer used in the present invention includes tetrafluoroethylene-α-olefin copolymers such as tetrafluoroethylene-propylene copolymer, vinylidene fluoride-hexafluoropropylene. Examples thereof include copolymers, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymers, vinylidene fluoride-perfluoroethylene copolymers, and the like. Among these, THV-based fluorine-containing thermoplastic copolymers Excellent compatibility with
It is preferable to use a tetrafluoroethylene-propylene-based copolymer that 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, when the light-colored compound is not required, the number average molecular weight is not particularly limited, but when the light-colored compound 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.

The crystalline fluororesin used in the present invention is preferably a copolymer having a hydrogen atom in the side chain, such as polyvinylidene fluoride, ethylene-tetrafluoroethylene copolymer, ethylene-chlorotriene. A fluoroethylene copolymer, or a fluorine-based copolymer having a hydrogen bond in the same side chain is preferable.

Similarly, the vinylidene fluoride-fluoroolefin copolymer used in the present invention has a fluoroolefin copolymerization amount of 1 to 20 mol%. As such a fluoroolefin, propylene hexafluoride or tetrafluoroethylene is most preferable from the viewpoint of processability and the like. As can be seen from the composition ratio, the vinylidene fluoride-fluoroolefin copolymer used here has a completely different composition ratio from the above-mentioned fluorine-containing thermoplastic copolymer and fluororubber copolymer. However, it is a polymer having completely different physical properties.

By adding these crystalline fluororesins and / or vinylidene fluoride-fluoroolefin copolymer, not only the mechanical strength of the composition is improved, but also the composition is used as a heat shrinkable tube. This is because in this case, the heat setting property (property of expanding the tube to maintain its original shape) is improved. At this time, crystalline fluororesin and / or vinylidene fluoride-
The blending amount of the fluoroolefin copolymer is 40 parts by weight or less, preferably 5 to 20 parts by weight.

The reason why the blending amount of these crystalline fluororesins and / or vinylidene fluoride-fluoroolefin copolymers is 40 parts by weight or less is that the heat setting property is saturated even if they are blended further, and the mechanical properties are mechanically increased. This is because the decrease in the elongation rate becomes remarkable.

In general, these crystalline fluororesins and vinylidene fluoride-fluoroolefin copolymers used herein may be used alone if they have a total compounding amount of 40 parts by weight or less as described above. It may be either a mixture of two or more species.

On the other hand, the fluorine-containing thermoplastic copolymer used in the present invention, as described above, is different from the conventional vinylidene fluoride-propylene hexafluoride copolymer and vinylidene fluoride depending on the composition ratio and the presence or absence of the melting point. It is a completely different polymer from fluororubber or fluororesin copolymer such as propylene hexafluoride-tetrafluoroethylene copolymer and vinylidene fluoride-fluoroolefin 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 above-mentioned fluorine-containing thermoplastic copolymer and fluororubber copolymer must be blended in a weight ratio within the range of 98: 2 to 40:60.

When the fluororubber copolymer content is low such that the weight ratio of the fluororubber copolymer to the fluororubber copolymer is less than 98: 2, the molded article is prevented from thermal softening. In order to maintain a sufficient degree of cross-linking, it is necessary to blend the polyfunctional monomer in an amount of 5 parts by weight or more, and as a result, the amount of the filler must be increased, resulting in an increase in hardness of the molded product. Stretchability is also lost.

On the contrary, when the fluororubber copolymer is blended in an amount of more than 40:60, the mechanical strength is remarkably lowered, which is not preferable in practice. The most preferable mixing ratio is 95: 5 or more and 75:25 or less in terms of the weight ratio of the fluorine-containing thermoplastic copolymer and the fluororubber copolymer.

Generally, in order to improve the compatibility or extrudability of these compositions, an ethylene polymer or an organic silicone compound may be mixed.

Examples of the ethylene-based polymer used in this case include homopolymers or copolymers of olefins such as ethylene, propylene, butene, octene, dicyclopentadiene and ethylidene norbornene. Examples of the combination include the above polyolefins and vinyl acetate, ethyl acrylate, methyl acrylate,
Examples thereof include copolymers with ethyl acrylate, ethyl methacrylate and the like, but ethylene-vinyl acetate copolymers are particularly preferably used.

It is most preferable to use those ethylene polymers which have no melting point or have a melting point of 100 ° C. or less.

The blending 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.

Examples of organic silicone compounds include, for example, dimethyl silicone oil, methylphenyl silicone oil, methylhydrogen silicone oil, alkoxysilane compounds, silazane compounds, organosilane compounds such as chlorosilane compounds, epoxies, alkyls. , Modified silicone compounds modified with alkylaralkyl, amino, carboxyl, alcohol, fluorine, alkylaralkylpolyether, polyether, γ- (2-aminoethyl) aminopropylsilane, trimethoxysilane, aminosilane, γ -Methacryloxypropyltrimethoxysilane, n-β- (N-
Vinylbenzylaminoethyl) -γ-aminopropylmethoxysilane hydrochloride, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, vinyltriacetoxysilane, γ-chloropropyltrimethoxysilane, γ-anilino Propyltrimethoxysilane, vinyltrimethoxysilane, octadecyldimethyl [3- (trimethoxysilyl) propyl] ammonium chloride, γ-chloropropylmethyldimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane , Γ-unidopropyltriethoxysilane, γ-
Silane coupling agents such as methacryloxypropylmethyldimethoxysilane, silane compounds such as methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, dimethylbutylchlorosilane, dimethyloctadecylchlorosilane, and methyltrimethoxysilane, and normally commercially available silicone rubber. Examples thereof include fluorosilicone rubber, methylphenyl silicone rubber, dimethyl silicone rubber, methyl vinyl silicone rubber and the like.

Generally, among these organic silicone compounds, it is most preferable to use commercially available silane coupling agents or commercially available silicone rubbers, and the compounding amount is usually 10 parts by weight or less (of the silane coupling agent). Case 5
(Parts by weight or less) is most desirable.

The silicone rubber referred to herein may be used by blending one or two or more kinds of silicone rubber selected from the above group, and the form thereof is gum-like raw rubber or reinforced to raw rubber. Any form may be used, such as a gum base form to which agents and the like are added, and a U-stock form which is a usual commercially available form in which a filler is added to the gum base.

If these ethylene-based polymers and organic silicone-based compounds are blended in amounts exceeding the above-mentioned blending amounts, the heat resistance is deteriorated (ethylene-based polymers) and the mechanical properties of the composition are significantly lost (organic-silicone-based compounds). Compound)
Therefore, although not preferred, both may be used alone or in combination of two or more as long as they are within the above blending amount range.

Further, examples of the cross-linking aid used for achieving 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 from the viewpoint of improving the degree of crosslinking of the composition and less staining to the composition, and the amount of the compound is from the viewpoint of both improving the crosslinking degree and saturating the effect. , Usually 2 to 10 parts by weight, preferably 3 to 5 parts by weight.

Further, an inorganic filler is usually used in order to facilitate the kneading of the crosslinking aid and the resin and rubber components at the time of 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 reduce 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 blended in a large amount. Therefore, it is preferable to blend the resin and the rubber component and the polyfunctional monomer in the minimum necessary amount. 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 by 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 generally be carried out by lowering the molding temperature, but since vulcanization time becomes very long and moldability is poor, it is usually preferable to carry out crosslinking by ionizing radiation.

[0043]

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

[0044]

Examples 1 to 8 and Comparative Examples 1 to 5 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. According to the compounding ratio, the crystalline fluororesin or vinylidene fluoride-fluoroolefin copolymer having the highest melting point was charged into a 3 liter pressure type kneader preheated to a temperature 20 ° C. higher than the melting point. At this time, the amount of the filler was set to the minimum number of parts that enables kneader kneading. The pressure lid was lowered, one rotation speed of the pair of rotary blades was set to 29 rpm, and the other rotation speed was set to 43 rpm to start kneading. First, the polymer alone was kneaded for 2 minutes, and 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.

Among these kneaded products, those not blended with the crystalline fluororesin or vinylidene fluoride-fluoroolefin copolymer, the die temperature was 180 ° C. and the head temperature was 1
Using a 40 mm extruder (L / D = 22) set at 80 ° C., cylinder 1 temperature 170 ° C., and cylinder 2 temperature 130 ° C., extrusion molding was performed into a tube having an inner diameter of 2.5 mm and a wall thickness of 0.5 mm.

The crystalline fluororesin or the vinylidene fluoride-fluoroolefin copolymer blend was 40 mm in which the die temperature was 250 ° C., the head temperature was 250 ° C., the cylinder 1 temperature was 230 ° C., and the cylinder 2 temperature was 180 ° C. Using an extruder (L / D = 22), an inner diameter of 2.
It was extruded into a tube shape having a thickness of 5 mm and a 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.

Further, after heating the crosslinked tube in a heating furnace at 150 ° C., an internal pressure (5 kg / mm ² ) is applied in an outer diameter control die so that the outer diameter becomes 5 mm, and after cooling, a heat shrinkable tube. It was created.

The tensile strength, elongation, heat softening property, hardness and heat setting property of the heat shrinkable tube produced as described above were measured. These measuring methods are as follows.

(1) The initial tensile strength and the initial elongation are JIS C 3005 as compared with those of the tube before heat shrink processing.
The tube shape was measured in accordance with (Insulator tensile test). Here, initial tensile strength of 15 MPa or more and initial elongation rate of 200% or more are general required values.

(2) Regarding the heat softening property, a crosslinked tube (a tube before heat shrinking) is cut into a length of about 10 cm, placed flat in an oven at 180 ° C. and left for 15 minutes. JIS C 2133 (test method for electrically insulating tubes) 6. According to the dimensions, the minimum outside 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, ○, 8
If it is less than 0%, the result is x.

[0052]

[Equation 1]

(3) The hardness was measured according to JIS K 6253, by tearing the crosslinked tube before heat shrinking in the longitudinal direction,
Three such test pieces were stacked to form a micro test piece, and the type D durometer hardness was directly read using a Wallace type hardness tester (type D durometer push needle). Here, the general requirement value is 50 or less.

(4) The heat setting property was determined by allowing the heat shrinkable tube to stand at room temperature for 24 hours and then measuring the inner diameter of the heat shrinkable tube before and after the thermal expansion process. If yes, it was rated as X, and if it was less than that, it was rated as X.

[0055]

[Equation 2]

The results are shown in Tables 1 and 2.

[0057]

[Table 1]

[0058]

[Table 2]

As is clear from the results shown in Tables 1 and 2, Examples 1 to 8 are excellent in initial tensile strength, initial elongation, thermal softening property and heat setting property, and are not so bent as conventional ones. The hardness could be maintained to the extent that flexibility did not change.

On the other hand, when the content of fluororubber is low (Comparative Example 1), the heat softening property is not improved, and an inorganic filler and a polyfunctional monomer are blended in order to improve the heat softening property ( Even in Comparative Example 2) or when an inorganic filler, a polyfunctional monomer and a crystalline fluororesin were blended (Comparative Example 3), when the content of fluororubber was low, the initial elongation rate was significantly reduced and the hardness was also high. Higher and more difficult to bend.

On the other hand, when the amount of the fluororubber compounded is too large, the initial tensile strength is significantly lowered (Comparative Example 4).

Further, when the crystalline fluororesin or vinylidene fluoride-fluoroolefin copolymer is blended in an appropriate amount or more (Comparative Example 5), the initial elongation is lowered, the hardness is increased, and the tube becomes very difficult to bend. Will end up.

Further, in the case of a composition containing only a fluororubber copolymer and a vinylidene fluoride-fluoroolefin copolymer and not containing a fluorine-containing thermoplastic copolymer (Comparative Examples 6 and 7).
Then, the initial tensile strength is low, the hardness is high, and it becomes very difficult to bend.

Further, when the compounding amount of the vinylidene fluoride-fluoroolefin copolymer is increased, this phenomenon becomes particularly remarkable.

[0065]

EFFECTS OF THE INVENTION The fluorine-containing resin composition of the present invention can be blended in a bright color and is excellent in mechanical strength, mechanical extensibility and heat setting property, and has the same bendability as conventional products and at high temperature. However, it is possible to obtain a molded product that does not cause 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 the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location C08F 214: 28)

Claims (1)

[Claims] 1. The composition ratio of vinylidene fluoride, propylene hexafluoride and tetrafluoroethylene is 10:35:55, 10:
A fluorine-containing thermoplastic copolymer within a range surrounded by four points of 15:75, 55: 5: 40, 55:15:30,
Weight ratio of fluororubber copolymer to 98: 2 to 40: 6
A fluorine-containing resin composition, characterized in that 40 parts by weight or less of a crystalline fluororesin and / or vinylidene fluoride-fluoroolefin copolymer is mixed with 100 parts by weight of the composition blended within the range of 0.