JP2017045638A - Fluorine resin composition for wire coating material and wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluorine resin composition for wire coating material capable of providing a wire excellent in stress crack property and the wire having a coating material formed from the fluorine resin composition for wire coating material.SOLUTION: There is provided a fluorine resin composition for wire coating material containing a fluorine-containing copolymer which is capable of melting molding and has the melting point of 250°C or more and at least one kind of adhesive selected from a group consisting of magnesium oxide and calcium hydroxide and having content of the adhesive of 0.05 to 1.0 pts.mass based on 100 pts.mass of the fluorine copolymer or there is provided a fluorine resin composition for wire coating material containing the fluorine-containing copolymer and an additive consisting of hydrotalcite and having content of the adhesive of 0.1 to 0.5 pts.mass based on 100 pts.mass of the fluorine copolymer.SELECTED DRAWING: None

Description

  The present invention relates to a fluororesin composition for an electric wire covering material and an electric wire.

  Fluororesin is excellent in heat resistance, flame resistance, chemical resistance, weather resistance, non-adhesiveness, low friction, low dielectric properties, etc., chemical plant corrosion resistant piping materials, agricultural greenhouse materials, release coatings for kitchen appliances It is used in a wide range of fields as materials, coating materials for heat-resistant and flame-retardant wires. It is also applied as a coating material for electric wires (for example, Patent Document 1).

JP 2006-66329 A

In recent years, electric wire coating materials have come to be applied to electric wires used under high temperature conditions such as aircraft and automobiles. Such applications are required to have stress crack resistance that does not cause cracking even when exposed to high temperatures.
However, the fluororesin composition described in Patent Document 1 and the like has a problem that the resulting wire has insufficient stress crack resistance.

  The present invention has been made in view of the above circumstances, and is a fluororesin composition for an electric wire covering material that can provide an electric wire excellent in stress crack resistance, and a covering material formed from the fluororesin composition for an electric wire covering material It is an object of the present invention to provide an electric wire having:

As a result of intensive studies by the present inventors, a fluororesin composition obtained by blending a small amount of at least one additive selected from the group consisting of magnesium oxide and calcium hydroxide, or an additive consisting of hydrotalcite The present invention has found that the above problems can be solved, and has completed the present invention.
That is, the present invention can be melt-molded, and includes a fluorine-containing copolymer having a melting point of 250 ° C. or higher, and at least one additive selected from the group consisting of magnesium oxide and calcium hydroxide, The content of the additive is 0.05 to 1.0 part by mass with respect to 100 parts by mass of the fluorine-containing copolymer, or
It includes a fluorine-containing copolymer having a melting point of 250 ° C. or higher and an additive comprising hydrotalcites, and the additive content is 100 parts by mass of the fluorine-containing copolymer. On the other hand, it is the fluororesin composition for electric wire coating materials which is 0.1-0.5 mass part.

  ADVANTAGE OF THE INVENTION According to this invention, the electric wire which has the coating | covering material formed from the fluororesin composition for electric wire coating materials which can provide the electric wire which is excellent in the stress crack-proof characteristic, and the said fluororesin composition for electric wire coating materials is provided. it can.

The present invention has the following aspects.
<1> A melt-moldable, containing a fluorine-containing copolymer having a melting point of 250 ° C. or higher, and at least one additive selected from the group consisting of magnesium oxide and calcium hydroxide, and the additive Content of the resin is 0.05 to 1.0 part by mass with respect to 100 parts by mass of the fluorine-containing copolymer.
<2> It can be melt-molded and contains a fluorine-containing copolymer having a melting point of 250 ° C. or higher and an additive made of hydrotalcite, and the content of the additive is the fluorine-containing copolymer 100. The fluororesin composition for electric wire coating materials which is 0.1-0.5 mass part with respect to a mass part.
<3> The fluorine-containing copolymer is selected from the group consisting of a tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer, a tetrafluoroethylene / hexafluoropropylene copolymer, and an ethylene / tetrafluoroethylene copolymer. The fluororesin composition for wire covering materials according to <1> or <2>, which is at least one fluororesin.
<4> An electric wire having a core wire and a covering material covering the surface of the core wire, wherein the covering material is a fluororesin for an electric wire covering material according to any one of <1> to <3>. An electric wire composed of a composition.
<5> The electric wire according to <4>, wherein the covering material has a thickness of 3 mm or less.

[Fluorine resin composition for wire coating materials]
The fluororesin composition for a wire coating material of the present invention can be melt-molded and is at least one selected from the group consisting of a fluorine-containing copolymer having a melting point of 250 ° C. or higher, magnesium oxide, and calcium hydroxide. And the additive content is 0.05 to 1.0 part by mass with respect to 100 parts by mass of the fluorinated copolymer, or
It includes a fluorine-containing copolymer having a melting point of 250 ° C. or higher and an additive comprising hydrotalcites, and the additive content is 100 parts by mass of the fluorine-containing copolymer. On the other hand, it is 0.1 to 0.5 part by mass.
The “fluorine-containing copolymer that can be melt-molded” is a fluorine-containing copolymer that exhibits melt fluidity. Specifically, it means a fluorine-containing copolymer having a melt flow rate (hereinafter also referred to as “MFR”) at a temperature 20 ° C. or more higher than the melting point of 0.5 g / 10 min or more.
Hereinafter, the fluororesin composition for a wire coating material of the present invention will be described in detail.

<Fluorine-containing copolymer>
The fluorine-containing copolymer which can be melt-molded and has a melting point of 250 ° C. or higher is not particularly limited as long as it has the effects of the present invention, and conventionally known ones can be used. Among these, from the viewpoint of improving the bending resistance of the obtained electric wire, a copolymer having a unit based on tetrafluoroethylene is preferable, and heat resistance, slidability, and HF gas generated during molding can be reduced. From such viewpoints, a tetrafluoroethylene / fluoroalkyl vinyl ether copolymer (hereinafter referred to as PFA), a tetrafluoroethylene / hexafluoropropylene copolymer (hereinafter referred to as FEP), and an ethylene / tetrafluoroethylene copolymer. It is preferably at least one fluororesin selected from the group consisting of polymers (hereinafter referred to as ETFE).

PFA has units based on tetrafluoroethylene and units based on fluoroalkyl vinyl ether.
Examples of the fluoroalkyl vinyl ether include compounds represented by the following formula (I).
CF ₂ = CF—O—R ^f (I)
In formula (I), ^Rf is a C1-C10 fluoroalkyl group.
Of these, perfluoro (alkyl vinyl ether) is preferred as the fluoroalkyl vinyl ether from the viewpoint of further improving the heat resistance of the molded article.

The molar ratio of units based on tetrafluoroethylene and units based on fluoroalkyl vinyl ether in PFA (units based on tetrafluoroethylene / units based on fluoroalkyl vinyl ether) is preferably 92/8 to 99/1.
If the ratio of each unit is in the above range, the resulting PFA has a melting point of 250 ° C. or higher, which is preferable. Moreover, since heat resistance and fluidity | liquidity become favorable, it is preferable.
Further, PFA having a mass average molecular weight of 100,000 to 900,000 is preferable. Moreover, 295-315 degreeC is preferable and, as for melting | fusing point of PFA, 300-310 degreeC is more preferable.
In the present specification, the mass average molecular weight of the fluorine-containing copolymer is a value calculated from the value of the storage elastic modulus G ′ using a melt shear dynamic viscoelasticity measuring apparatus.

FEP has units based on tetrafluoroethylene and units based on hexafluoropropylene.
The molar ratio of units based on tetrafluoroethylene and units based on hexafluoropropylene in FEP (units based on tetrafluoroethylene / units based on hexafluoropropylene) is preferably 80/20 to 99/1.
If the ratio of each unit is in the above range, the melting point of the FEP obtained is preferably 250 ° C. or higher. Moreover, since heat resistance and fluidity | liquidity become favorable, it is preferable.
Further, the FEP preferably has a mass average molecular weight of 100,000 to 900,000. Moreover, 250-270 degreeC is preferable and, as for melting | fusing point of FEP, 255-265 degreeC is more preferable.

ETFE has units based on ethylene and units based on tetrafluoroethylene.
The molar ratio of units based on tetrafluoroethylene and units based on ethylene in ETFE (units based on tetrafluoroethylene / units based on ethylene) is preferably 45/65 to 65/35.
If the ratio of each unit is in the above range, the melting point of ETFE obtained is preferably 250 ° C. or higher. Moreover, since fluidity | liquidity becomes favorable, it is preferable.
In addition, ETFE preferably has a mass average molecular weight of 100,000 to 900,000. Moreover, 250-280 degreeC is preferable and, as for melting | fusing point of ETFE, 255-265 degreeC is more preferable.

  As described above, the fluorinated copolymer is preferably at least one fluororesin selected from the group consisting of PFA, FEP, and ETFE. Among these, ETFE is more preferable from the viewpoint of the formability of the electric wire.

The aforementioned PFA, FEP, or ETFE may have units based on other monomers as long as the essential properties of each fluororesin are not impaired.
In the case of PFA, it may have units based on monomers other than tetrafluoroethylene and fluoro (alkyl vinyl ether).
In the case of FEP, it may have units based on monomers other than tetrafluoroethylene and hexafluoropropylene.
In the case of ETFE, it may have units based on monomers other than ethylene and tetrafluoroethylene.

Examples of other monomers include hexafluoropropylene (except when the fluororesin is FEP), fluoroalkyl vinyl ether (preferably perfluoro (alkyl vinyl ether), provided that the fluororesin is PFA. Except for the case.), Fluoroalkylethylene (preferably perfluoroalkylethylene having 1 to 10 carbon atoms in the alkyl group), fluoroalkylallyl ether (preferably perfluoroalkyl having 1 to 10 carbon atoms in the alkyl group) Allyl ether), compounds represented by the following formula (II), and the like.
CF ₂ = CF [OCF ₂ CF (CF ₃ )] _n OCF ₂ (CF ₂ ) _p X (II)
However, in formula (II), X is a halogen atom, n is an integer of 0-5, and p is an integer of 0-2.
The proportion of units based on other monomers is preferably 50 mol% or less, more preferably 0.01 to 5 mol%, based on the total (100 mol%) of all units of PFA, FEP, or ETFE.
In the present specification, the “monomer” means a compound having a polymerizable carbon-carbon double bond.

The fluorine-containing copolymer has at least one functional group selected from the group consisting of a carbonyl group-containing group, a hydroxy group, an epoxy group, and an isocyanate group (hereinafter referred to as functional group (1)). May be. By having the functional group (1), when the fluororesin composition for an electric wire covering material of the present invention containing the above-mentioned fluorinated copolymer is used as an electric wire covering material, the adhesiveness to the core wire can be improved, which is preferable.
Here, the carbonyl group-containing group is a group containing a carbonyl group (—C (═O) —) in the structure. Examples of the carbonyl group-containing group include a group having a carbonyl group between carbon atoms of a hydrocarbon group, a carbonate group, a carboxy group, a haloformyl group, an alkoxycarbonyl group, an acid anhydride residue, and the like.
The functional group (1) is present at one or both of the main chain terminal and the side chain of the fluorine-containing copolymer. Here, the “main chain” refers to a main carbon chain of a chain compound, and in this specification, refers to a trunk portion having the maximum number of carbon atoms.
Moreover, only 1 type may be sufficient as a functional group (1), and 2 or more types may be contained.

<Additives>
The fluororesin composition for wire covering material of the present invention has at least one additive selected from the group consisting of magnesium oxide and calcium hydroxide (hereinafter referred to as “additive A”) in addition to the above-mentioned fluorine-containing copolymer. Or an additive composed of hydrotalcites (hereinafter sometimes referred to as “additive B”).
The additive A is contained in an amount of 0.05 to 1.0 part by mass with respect to 100 parts by mass of the fluorinated copolymer, or the additive B is added in an amount of 0.1 to 0.00 with respect to 100 parts by mass of the fluorinated copolymer. By including 5 parts by mass, it is possible to improve the stress crack resistance of the obtained electric wire.

As the additive A, conventionally known additives can be used. Of these, magnesium oxide that is not subjected to surface treatment is preferable.
The compounding quantity of the additive A is 0.05-1.0 mass part with respect to 100 mass parts of fluorine-containing copolymers. From the viewpoint of further improving the stress crack resistance of the obtained electric wire, 0.2 to 0.8 parts by mass is preferable, and 0.3 to 0.5 parts by mass is more preferable.
If the amount of additive A is within the above range, it is preferable because good stress crack resistance can be obtained. On the other hand, if the blending amount of the additive A in the fluororesin composition is too large, foaming occurs during molding, and an appearance defect occurs in the final product, which is not preferable.
Magnesium oxide and calcium hydroxide may be used together or may not be used together, and from the viewpoint of further excellent stress crack resistance, it is preferable not to use them together, and it is more preferable to use magnesium oxide alone.

Additive B has high environmental safety.
The additive B is not particularly limited as long as it has the effect of the present invention.
The hydrotalcite used in the present invention may be a natural product or a synthetic product.
Specific examples include those represented by the following formulas (III) to (V).
Mg ₃ ZnAl ₂ (OH) ₁₂ CO ₃ · wH ₂ O (III)
(In formula (III), w represents a positive real number.)
_{Mg x Al y (OH) 2x} + 3y-2 CO 3 · wH 2 O ··· (IV)
(In formula (IV), x represents 1 to 10, y represents 1 to 10, and w represents a positive real number.)
_{Mg x Al y (OH) 2x} + 3y-2 CO 3 ··· (V)
(In the formula (V), x represents 1 to 10, and y represents 1 to 10.)

More specifically, as hydrotalcites, for example, Mg _4.3 Al ₂ (OH) _12.6 CO ₃ , Mg _1-x Al _x O _3.83x (provided that 0.2 ≦ x <0.5 .).
Commercially available hydrotalcites include KW series (KW-2000, KW-2100, KW-2200, etc., chemical composition: Mg _0.3 Al _0.7 O _1.15 ) manufactured by Kyowa Chemical Industry Co., Ltd. DHT series (DHT-4A (registered trademark), DHT-4A-2, DHT-4C, etc., chemical composition: Mg _4.3 Al ₂ (OH) _12.6 CO ₃ · mH ₂ O), Sakai Chemical Industry STABIACE (registered trademark) HT series manufactured by the company.

  Hydrotalcites are preferably those having a particle size of 0.05 to 20 μm, more preferably those having a particle size of 0.1 to 15 μm. If the particle size of the hydrotalcite is within the above range, the effect of stress cracking resistance of the electric wire can be obtained, which is preferable. The particle size of hydrotalcites is a value measured under the condition of being dispersed by ultrasonic waves in isopropyl alcohol using a laser type particle size distribution analyzer.

The blending amount of the additive B is 0.1 to 0.5 parts by mass with respect to 100 parts by mass of the fluorinated copolymer, and 0.2 to 0 from the viewpoint of improving the stress cracking resistance of the obtained electric wire. 0.5 parts by mass is preferable, and 0.3 to 0.5 parts by mass is particularly preferable.
A blending amount of the additive B within the above range is preferable because good stress crack resistance can be obtained. On the other hand, if the amount of additive B in the fluororesin composition is too large, foaming occurs during molding, and an appearance defect occurs in the final product, which is not preferable.
Additive A and additive B may be used together or not used together, and it is preferable not to use them together in terms of further excellent stress crack resistance.

<Other ingredients>
The fluororesin composition for an electric wire covering material of the present invention may contain other components for expressing various properties desired for the electric wire covering material.
Other components include, for example, fibrous fillers (glass fiber, carbon fiber, boron fiber, aramid fiber, liquid crystal polyester fiber, stainless steel microfiber, etc.), powder fillers (talc, graphite, molybdenum disulfide, polytetra Fluoroethylene, calcium carbonate, silica alumina, alumina, titanium dioxide, etc.), carbon black (black pigment), iron oxide (red pigment), aluminum cobalt oxide (blue pigment), copper phthalocyanine (blue pigment, green pigment), perylene (Red pigment), bismuth vanadate (yellow pigment) and the like. The content of other components can be appropriately selected depending on the properties to be imparted.

<MFR>
The MFR of the fluororesin composition for wire covering material of the present invention is the melting point of the fluorine-containing copolymer (if the fluorine-containing copolymer contains a plurality of fluororesins having different melting points, the highest melting point among those melting points) It is a value at a temperature 20 ° C. or higher.
The MFR of the fluororesin composition for electric wire coating material is the extrusion rate from an orifice having an inner diameter of 2.1 mm and a length of 8 mm under a predetermined measurement condition, that is, the fluororesin composition for electric wire coating material that flows out from the orifice in 10 minutes. It is calculated | required as a mass (g / 10min). The same applies to the MFR of the fluorine-containing copolymer.
The measurement method of MFR is defined by ASTM. For example, the measurement temperature and load are defined by the type of fluororesin as follows. The measurement conditions corresponding to the fluorine-containing copolymer contained are typically employed as the measurement conditions for the MFR of the fluororesin composition for wire covering materials.
PFA: ASTM D3307, measuring temperature 372 ° C., load 49 N.
FEP: ASTM D2116, measuring temperature 372 ° C., load 49 N.
ETFE: ASTM D3159, measurement temperature 297 ° C., load 49 N.

  The MFR of the fluororesin composition for an electric wire coating material can be adjusted by the MFR of the fluorinated copolymer, the kneading conditions (such as the average discharge amount of the kneaded material) when producing the fluororesin composition for the electric wire coating material, and the like.

<Method for producing fluororesin composition for wire covering material>
The manufacturing method of the fluororesin composition for electric wire coating materials of this invention can be manufactured by melt-kneading the fluorine-containing copolymer which can be melt-molded, and additive A or additive B. Examples of the melt kneading method include a method using an apparatus equipped with a screw.

  As an apparatus provided with a screw, an apparatus capable of adjusting the discharge amount and the screw rotation speed is used. Examples of the device provided with the screw include a twin screw extruder, a single screw extruder, a kneader, and a mixer. Of these, a twin-screw extruder is preferable from the viewpoint of productivity, and a twin-screw extruder having an L / D of 20 or more from the viewpoint of efficiently melt-kneading a melt-formable fluorine-containing copolymer and an additive. More preferred is a twin-screw extruder having an L / D of 25 to 100.

  The temperature at the time of melt-kneading is appropriately set depending on the type of fluorine-containing copolymer that can be melt-molded. When using FEP or ETFE, 260-380 degreeC is preferable, 270-370 degreeC is more preferable, 280-350 degreeC is further more preferable. When using PFA, 300-420 degreeC is preferable, 310-400 degreeC is more preferable, and 320-360 degreeC is further more preferable.

  The kneaded material discharged from the tip end of the screw is usually extruded into a strand form from a die provided at the tip end of the apparatus and then cut by a pelletizer to form a pellet-shaped fluororesin composition for an electric wire coating material. .

<Wire>
The electric wire of the present invention has a core wire and a covering material covering the surface of the core wire, and the covering material is composed of the fluororesin composition for an electric wire covering material of the present invention. .

  The core wire (conductor) is not particularly limited as long as it has the effect of the present invention. For example, copper, copper alloy, aluminum and aluminum alloy, tin plating, silver plating, nickel plating, various plating wires, stranded wire, superconductor, Examples thereof include plated wires for semiconductor element leads.

  3 mm or less is preferable, as for the thickness of the coating | covering material which consists of a fluororesin composition for electric wire coating | covering materials of this invention, 0.005-2.5 mm is more preferable, and 0.010-1.5 mm is further more preferable. If the thickness of the coating material is within the above range, it is preferable because the handleability of the electric wire is excellent, and the electric insulation and bending resistance are further excellent.

<Manufacturing method of electric wire>
The electric wire of this invention can be manufactured by coat | covering the surface of a core wire with the fluororesin composition for electric wire coating materials of this invention.
The core wire can be coated with the fluororesin composition for electric wire coating material by a known molding method such as an extrusion molding method. For example, the molding method (electric wire extrusion molding) which extrudes so that a molten fluororesin composition for wire coating materials may be coat | covered on a core wire using an extruder is mentioned.

  The electric wire of the present invention described above is excellent in stress crack resistance because it includes the coating material made of the fluororesin composition for electric wire coating material of the present invention.

(Function and effect)
The fluororesin composition for wire covering material of the present invention can be melt-molded, and by adding a small amount of additive A or additive B to a fluorine-containing copolymer having a melting point of 250 ° C. or higher, stress resistance is improved. An electric wire having excellent crack characteristics can be provided.
Therefore, the fluororesin composition for a wire covering material of the present invention is suitably used for a covering material in an electric wire (aircraft wire, high-voltage wire, communication wire, electric heater wire, etc.) requiring high heat resistance. Can do.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited by the following description.
(Method for producing fluororesin composition for wire covering material)
(Examples and Comparative Examples)
The additives shown in the table are uniformly mixed by dry blending with respect to 100 parts by mass of the fluorinated copolymer, and then the compounding material is put into a twin screw extruder (Technobel KZW15TW-45MG), and the resin discharge amount 2 Melting and kneading was performed at 0.0 kg / hr, a screw rotation speed of 200 rpm, and a set resin temperature of 300 ° C. to obtain pellets of a fluororesin resin composition for wire coating materials.

The fluorine-containing copolymer used is as follows.
ETFE: units based on ethylene / units based on tetrafluoroethylene / CH ₂ ═CH (CF ₂ ) ₄ F units = 54/46 / 1.4 (mol%) (melting point: 260 ° C.)
PFA: units based on tetrafluoroethylene / CF ₂ = CFO (CF ₂ ) ₃ units based on 3F = 98/2 (mol%) (melting point: 300 ° C.)

The additives used are as follows.
(Additive A)
Magnesium oxide (trade name: Kyowa Mag (registered trademark) 150, manufactured by Kyowa Chemical Industry Co., Ltd.)
・ Calcium hydroxide (trade name: Calbit (registered trademark), manufactured by Omi Chemical Co., Ltd.)
(Additive B)
Hydrotalcite 1: (trade name: DHT-4A (registered trademark), manufactured by Kyowa Chemical Industry Co., Ltd.)
Hydrotalcite 2: (Product name: Alkamizer (registered trademark), manufactured by Kyowa Chemical Industry Co., Ltd.)
(Additive C)
・ Mica (trade name: MK-200, manufactured by Corp Chemical)
Silica (trade name: Aerosil (registered trademark) OX-1, manufactured by Evonik)
These fluorine-containing copolymers and additives A, B, or C were mixed in the ratios shown in Tables 1 and 2 to obtain fluorine resin compositions for wire coating materials of Examples and Comparative Examples. The stress crack resistance characteristics of the obtained fluororesin composition for wire coating materials were evaluated according to the following methods. The results are shown in Tables 1-2.

(Evaluation of stress crack resistance)
Extruder (made by IK, MS30-25), screw (made by IKG, full flight, L / D = 24, φ30mm), electric wire die crosshead (made by Unitech, maximum conductor diameter 3mm, maximum die) Kneaded material and core wire (manufactured by Yasuda Kogyo Co., Ltd., tin-plated copper) obtained in Examples or Comparative Examples using a hole diameter of 20 mm), an electric wire take-up machine (manufactured by Holy Seisakusho), and a winder (made by Holy Seisakusho) Kneading wire, diameter: 1.8 mm, composition: 37 / 0.26 mm (1 layer: 7 right-handed strands, 2 layers: 12 left-handed strands, 3 layers: 18 right-handed strands)) An electric wire having a diameter of 0.5 mm and an electric wire diameter of 2.8 mm was manufactured. The wire was annealed at a predetermined temperature in increments of 5 ° C. for 96 hours, and then left overnight at room temperature. Next, the electric wire was wound around the electric wire itself by 8 turns or more (self-diameter winding) to prepare an electric wire sample.
The wire sample was heat-treated in a gear oven at 200 ° C. for 1 hour to check for cracks. The number of samples was 5.
From the lowest annealing temperature (T1) at which cracks occur in all five wire samples and the maximum annealing temperature (T2) at which no cracks occur in all five wire samples, the stress crack temperature (Tb) Was calculated.
Tb = T1- [Delta] T (S / 100-1 / 2)
In the above formula,
Tb: Stress crack temperature T1: Minimum annealing temperature at which cracks occur in all molded body samples ΔT: Annealing temperature interval (5 ° C.)
S: Crack occurrence probability at each temperature from the highest annealing temperature (T2) at which cracks do not occur in all molded body samples to the lowest annealing temperature (T1) at which cracks occur in all molded body samples (when 50% occurs) 0.5).
The stress crack temperature is an annealing temperature obtained by the above experiment, at which 50% of the wire sample is broken. A higher stress crack temperature means higher stress crack resistance.

From the results shown in Tables 1 and 2, electric wire coating in which 0.05 to 1.0 parts by mass of additive A is blended with respect to 100 parts by mass of the fluorinated copolymer having a melting point of 250 ° C. or higher is possible. In the fluororesin composition for wires, or in the fluororesin composition for wire coating materials in which 0.1 to 0.5 parts by mass of additive B is blended with 100 parts by mass of the fluorine-containing copolymer, both are stress cracks. It was found that the temperature was high and the stress crack resistance was excellent.
On the other hand, in the fluororesin composition for electric wire coating materials of Comparative Example 1 that does not contain additive A or additive B, the stress crack temperature is lower than that of the fluororesin composition for electric wire coating materials of the present invention, and the stress crack resistance is improved. I found it inferior. In the fluororesin compositions for electric wire coating materials of Comparative Examples 2 to 5 in which the amount of additive B was too large relative to the fluorinated copolymer, foaming occurred during molding, and no electric wire could be formed. In the fluororesin compositions for wire coating materials of Examples 6 and 7 in which the additive C (mica, silica) is blended instead of the additive A and the additive B, the stress is higher than that of the fluororesin composition for wire coating materials of the present invention. It was found that the crack temperature was low and the stress crack resistance was inferior. In the fluororesin composition for wire coating material of Comparative Example 8 in which the amount of additive A is too large relative to the fluorinated copolymer, the stress crack temperature is lower than that of the fluororesin composition for wire coating material of the present invention, It was found that the resistance to stress cracking was inferior.
From the above results, it was confirmed that the fluororesin composition for wire coating materials to which the present invention was applied was excellent in stress crack resistance.

Claims (5)

  A content of the additive, including a fluorine-containing copolymer having a melting point of 250 ° C. or higher and at least one additive selected from the group consisting of magnesium oxide and calcium hydroxide. However, The fluororesin composition for wire coating materials which is 0.05-1.0 mass part with respect to 100 mass parts of said fluorine-containing copolymers.   It includes a fluorine-containing copolymer having a melting point of 250 ° C. or higher and an additive comprising hydrotalcites, and the additive content is 100 parts by mass of the fluorine-containing copolymer. On the other hand, the fluororesin composition for electric wire coating materials which is 0.1-0.5 mass part.   The fluorine-containing copolymer is at least one selected from the group consisting of a tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer, a tetrafluoroethylene / hexafluoropropylene copolymer, and an ethylene / tetrafluoroethylene copolymer. The fluororesin composition for electric wire coating materials according to claim 1 or 2, which is a fluororesin.   It is an electric wire which has a core wire and the coating | covering material which has coat | covered the surface of the said core wire, Comprising: The said coating | covering material is comprised from the fluororesin composition for wire coating materials as described in any one of Claims 1-3. The electric wire.   The electric wire according to claim 4, wherein the covering material has a thickness of 3 mm or less.