JP5641497B2 - Heat-resistant and flame-retardant resin composition, insulated wire, and tube - Google Patents

Description

  The present invention provides a heat-resistant and flame-retardant resin composition that constitutes a coating material for electric wires used in a high-temperature environment, an insulated wire that is insulation-coated with the heat-resistant and flame-retardant resin composition, and the heat-resistant and flame-retardant resin composition. Related to the tube.

  A harness or the like in an engine room of an automobile is often exposed to a high temperature environment and is in contact with oil. Therefore, a resin composition which is a material for forming an insulating coating for these electric wires is required to have high heat resistance, high flame resistance, and high oil resistance in addition to high insulation properties. The insulating coating is required to have a higher mechanical strength, for example, excellent so-called cut-through characteristics, which is a property that the coating is not broken by contact with the edge portion. Also, in order to prevent problems such as the occurrence of insulation cracks when crimping the ends of insulated wires with crimp terminals, there are cases where excellent crimping workability is desired. In other words, high heat resistance, high oil resistance, high flame resistance, high insulation, excellent mechanical strength such as cut-through characteristics and crimp processability, etc. are balanced at a high level, and a low-cost resin composition There is a need for materials for insulating coatings.

  A fluorine-based elastomer is known as a coating material for electric wires used in a high-temperature environment. Fluorine-based elastomers are electrically insulating materials having a good balance of heat resistance, mechanical strength, etc., but are generally expensive and have poor cost performance.

  Furthermore, since the fluoroelastomer does not have a crystal component, the fluororubber electric wire insulated and coated with the fluoroelastomer has a problem in mechanical strength as compared with the resin-coated electric wire insulated and coated with a resin such as polyethylene. In particular, there is a problem that the cut-through characteristic is low. Further, when extruding the insulating coating, there is a problem that it is easily deformed by a load because it is not vulcanized immediately after extrusion, and is easily deformed when wound on a reel. Therefore, an expensive rubber extrusion line that performs extrusion and vulcanization in tandem is required for the production of fluororubber electric wires.

  As an electric wire to be wired in a high temperature environment, a silicone rubber electric wire insulated with silicone rubber is also known. However, since silicone does not have a crystal component and the intermolecular force is very weak, silicone rubber has particularly low mechanical strength and cut-through characteristics compared to a resin-coated electric wire coated with a resin such as polyethylene. Further, since silicone rubber is not usually vulcanized immediately after extrusion, there is a problem that it is easily deformed by a load and is easily deformed when wound on a reel. Therefore, an expensive rubber extrusion line for extruding and vulcanizing in tandem is also required for the production of electric wires in which the insulating coating is formed of silicone rubber.

  Patent Document 1 discloses that 100 wt. Of a tetrafluoroethylene-α-olefin copolymer as a fluorine-containing elastomer composition having improved mechanical strength and excellent cost performance while maintaining the heat resistance inherent in the fluorine-based elastomer. 10 to 70 parts by weight of a polyolefin composition containing an ethylenically unsaturated polar component is added to part, and the polyolefin composition contains 20 parts of polyethylene and an ethylene-ethylenically unsaturated polar monomer copolymer: A fluorine-containing elastomer composition that is mixed at a weight ratio of 80 to 98: 2 is disclosed.

Japanese Patent Laid-Open No. 10-316821

  However, the compatibility between the tetrafluoroethylene-α-olefin copolymer constituting the fluorine-containing elastomer composition described in Patent Document 1 and the polyolefin composition containing an ethylenically unsaturated polar component is not sufficient. Therefore, although the cut-through characteristics have been improved, the resin composition is still insufficient, and a resin composition capable of forming an insulating coating having more excellent cut-through characteristics is desired.

  As described above, none of the conventional resin compositions for insulation coating has excellent balance of mechanical strength such as insulation, heat resistance, flame retardancy, and cut-through characteristics, and satisfies recent requirements. It wasn't. Further, as mechanical strength, excellent crimping workability as well as tensile strength and cut-through characteristics are desired.

  The present invention relates to a resin composition that is well balanced and excellent in mechanical strength such as cut-through characteristics and crimping workability as well as insulation, heat resistance, oil resistance, and flame retardancy, and insulation comprising the resin composition. It aims at providing the tube which consists of an insulated wire which has a coating | cover, and the said heat-resistant flame-retardant resin composition.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventor blended random polypropylene with a fluororubber composition comprising a tetrafluoroethylene-α-olefin copolymer and a vinylidene fluoride-hexafluoropropylene copolymer. In addition, a resin composition containing an inorganic filler such as calcium carbonate and / or a flame retardant such as bromine-based flame retardant or antimony trioxide, and having a composition ratio of components within a specific range is crosslinked. It has been found that the mechanical strength such as insulation, heat resistance, oil resistance, flame retardancy, cut-through characteristics and crimping workability can be balanced at a high level, and further low cost can be achieved. completed.

  The invention according to claim 1 is an inorganic filler with respect to 100 parts by mass of a mixture of a fluororubber composition comprising a tetrafluoroethylene-α-olefin copolymer and a vinylidene fluoride-hexafluoropropylene copolymer and random polypropylene. A resin composition obtained by blending 10 to 100 parts by mass of an agent and further irradiating ionizing radiation to crosslink the fluororubber composition and random polypropylene, the tetrafluoroethylene-α-olefin copolymer and The mixing ratio of vinylidene fluoride-hexafluoropropylene copolymer is 80: 20-40: 60 (mass ratio), and the mixing ratio of the fluororubber composition and random polypropylene is 60: 40-90: 10. It is a heat-resistant flame-retardant resin composition characterized by being (mass ratio).

The tetrafluoroethylene-α-olefin copolymer is a copolymer of tetrafluoroethylene and α-olefin. The vinylidene fluoride-hexafluoropropylene copolymer is obtained by copolymerizing vinylidene fluoride represented by CH ₂ CF ₂ and hexafluoropropylene represented by C ₃ F ₆ . The former is a known fluororubber, and the latter is a known fluororesin. In the present invention, the mixing ratio of the tetrafluoroethylene-α-olefin copolymer and the vinylidene fluoride-hexafluoropropylene copolymer is 80: It is the range of 20-40: 60 (mass ratio), It is characterized by the above-mentioned.

  Tetrafluoroethylene-α-olefin copolymer is a component necessary for imparting mechanical strength and heat resistance as well as high insulation properties, and the mixing ratio thereof is tetrafluoroethylene-α-olefin copolymer and vinylidene. When the amount is less than 40% by mass relative to the total of the fluoride-hexafluoropropylene copolymer, the mechanical strength, particularly tensile elongation, of the resin composition decreases. Vinylidene fluoride-hexafluoropropylene copolymer is a necessary component for imparting high oil resistance. Therefore, when the mixing ratio is less than 20% by mass with respect to the total of the tetrafluoroethylene-α-olefin copolymer and the vinylidene fluoride-hexafluoropropylene copolymer, the oil resistance of the resin composition is lowered.

  The random polypropylene blended in the resin composition of the present invention is a copolymer in which ethylene and propylene are randomly copolymerized. As the random polypropylene, a random polypropylene having a melting point of 150 ° C. or lower is preferable. By blending random polypropylene in a predetermined ratio, it becomes possible to perform extrusion molding without using a dedicated rubber extrusion line, and high cut-through characteristics can be obtained. Furthermore, there is an effect of reducing the product cost.

  In the present invention, the mixing ratio of the fluororubber composition composed of tetrafluoroethylene-α-olefin copolymer and vinylidene fluoride-hexafluoropropylene copolymer to random polypropylene is 60:40 to 90:10 ( Mass ratio). When the mixing ratio of the random polypropylene is less than 10% by mass with respect to the total of the fluororubber composition and the random polypropylene, high cut-through characteristics cannot be obtained. On the other hand, when the mixing ratio of the fluororubber composition is less than 60% by mass (that is, when the mixing ratio of the random polypropylene exceeds 40% by mass), the mechanical strength such as tensile properties decreases, and particularly the heat resistance decreases. To do.

  Resin composition with low tensile properties, heat resistance, oil resistance and cut-through properties when using homopolypropylene as a homopolymer of propylene or block polypropylene as a block copolymer of ethylene and propylene instead of random polypropylene However, the object of the present invention is not achieved. High tensile properties, heat resistance, oil resistance and cut-through properties are considered to be achieved by cross-linking of the resin constituting the resin composition, while random polypropylene is used to cross-link the resin by ionizing radiation irradiation. It is necessary that homopropylene and block polypropylene are decomposed by irradiation with ionizing radiation.

  The inorganic filler blended in the resin composition of the invention according to claim 1 is inorganic particles blended for the purpose of reinforcement and increase in weight. Examples of the inorganic filler include heavy and light calcium carbonates, magnesium silicate minerals, aluminum silicate minerals, zinc oxide, silica, carbon, metal hydroxides, and those subjected to surface treatment. Can be mentioned. These inorganic fillers may be used alone or in combination of two or more. By adding an inorganic filler, the heat resistance and flame retardancy of the resin composition can be improved. In addition, the addition of an inorganic filler has the effect of reducing the product price. That is, by adding an inorganic filler, high heat resistance, high flame retardance, and low cost can be balanced at a high level.

  The present invention is also characterized in that the blending amount of the inorganic filler is in the range of 10 to 100 parts by mass with respect to 100 parts by mass of the mixture of the fluororubber composition and the random polypropylene. The resin composition of the present invention has a “continuous heat resistance temperature” (insulator elongation rate of 100 in 10,000 hours) as defined in the automotive standards (JASO) D609: 2001 and D611: 2009, even when an inorganic filler is not blended. %) Has a heat resistance of 200 ° C. or higher, but by setting the blending amount of the inorganic filler to 10 parts by mass or more, further excellent heat resistance can be obtained. Furthermore, the flame retardancy is improved by blending the inorganic filler, and the flame retardancy satisfying the standard usually required for insulated wires can be obtained without blending a flame retardant such as bromine-based flame retardant or antimony trioxide. On the other hand, when it exceeds 100 mass parts, there exists a tendency for a tensile characteristic to fall and for flexibility to be inferior.

  The invention described in claim 2 relates to 100 parts by mass of a mixture of a fluororubber composition comprising a tetrafluoroethylene-α-olefin copolymer and a vinylidene fluoride-hexafluoropropylene copolymer and random polypropylene. A resin composition obtained by blending less than part by mass of an inorganic filler and 3 to 20 parts by mass of a flame retardant, and further irradiating with ionizing radiation to crosslink the fluororubber composition and random polypropylene. Mixing ratio of ethylene-α-olefin copolymer and vinylidene fluoride-hexafluoropropylene copolymer is 80: 20-40: 60 (mass ratio), and mixing of the fluororubber composition and random polypropylene Heat-resistant flame retardant resin composition characterized in that the ratio is 60:40 to 90:10 (mass ratio) It is a thing.

  The tetrafluoroethylene-α-olefin copolymer, vinylidene fluoride-hexafluoropropylene copolymer, random polypropylene, and inorganic filler constituting the resin composition of the present invention are those of the invention described in claim 1. The same case is used. Further, the mixing ratio of tetrafluoroethylene-α-olefin copolymer and vinylidene fluoride-hexafluoropropylene copolymer, and tetrafluoroethylene-α-olefin copolymer and vinylidene fluoride-hexafluoropropylene copolymer The range of the mixing ratio of the fluororubber composition comprising the random polypropylene and the random polypropylene is the same as in the case of the invention described in claim 1. However, this invention is characterized in that the blending amount of the inorganic filler is less than 10 parts by mass, and 3 to 20 parts by mass of a flame retardant is blended.

  By making the blending amount of the inorganic filler less than 10 parts by mass, excellent crimping processability can be maintained, and problems such as the occurrence of insulation cracks when crimping the end of the wire with a terminal can be prevented. it can. The inorganic filler may not be blended.

  In addition, by blending 3 parts by mass or more of the flame retardant, flame retardancy that satisfies the standards normally required for insulated wires can be obtained even when the inorganic filler is little or not blended. On the other hand, blending 20 parts by mass or more of the flame retardant is not preferable because the mechanical strength is lowered. Examples of the flame retardant include those that generate non-flammable gases such as halogen-containing compounds, those that endothermically decompose like metal hydroxides, and those that form a burning shell that shields oxygen such as phosphate esters. Can be mentioned. Specifically, brominated flame retardant, antimony trioxide, chlorinated flame retardant, magnesium hydroxide, aluminum hydroxide, phosphate ester, ammonium polyphosphate, piperazine polyphosphate, red phosphorus, phosphinic acid metal salt, melamine cyanurate Etc.

  The resin composition according to claim 1 or 2 is obtained by irradiating an ionizing radiation such as an electron beam or a gamma ray to a mixture of the above composition by a conventional method to crosslink the fluororubber composition and the random polypropylene. It will be. When applying the resin composition of the present invention to an insulation coating of an insulated wire, it is preferable to irradiate with ionizing radiation after coating on the conductor by extrusion molding or the like from the viewpoint of the ease of the production process, and it is usually adopted. Is the way.

  By irradiating the resin composition with ionizing radiation, tensile properties, heat resistance, oil resistance and cut-through properties are improved. As the ionizing radiation, an electron beam that is widely used industrially, easily controlled, and capable of crosslinking at low cost is particularly preferable. For the electron beam irradiation, a known electron beam irradiation means usually used for resin crosslinking or the like can be used, and can be performed by a conventional method.

  The dose of ionizing radiation is selected so that the resin can be crosslinked to obtain desired tensile properties, heat resistance, oil resistance, and cut-through properties. In the case of electron beam irradiation, about 30 to 500 kGy is usually preferable.

  The invention according to claim 3 is characterized in that the tetrafluoroethylene-α-olefin copolymer is a tetrafluoroethylene-propylene copolymer, and the heat-resistant flame retardant according to claim 1 or 2 It is a resin composition. Specific examples of the tetrafluoroethylene-α-olefin copolymer include a copolymer of tetrafluoroethylene and propylene.

The invention according to claim 4 is the heat-resistant and flame-retardant resin composition according to any one of claims 1 to 3, wherein the inorganic filler is calcium carbonate. As the inorganic filler, calcium carbonate is preferable from the viewpoint of heat resistance, mechanical properties, and cost. Examples of calcium carbonate include heavy calcium carbonate obtained by mechanically pulverizing and classifying natural raw materials mainly composed of CaCO ₃ such as limestone, and chemically produced precipitated calcium carbonate (light calcium carbonate). Heavy calcium carbonate is preferred from the viewpoint of cost.

  Invention of Claim 5 is an insulated wire which has a coating layer which consists of a heat-resistant flame-retardant resin composition of any one of Claim 1 thru | or 4 on a conductor. That is, an electric wire having an insulation coating formed of the heat-resistant and flame-retardant resin composition of the present invention, and therefore mechanical properties such as high heat resistance, flame resistance, oil resistance, cut-through characteristics, and high crimping workability It is an electric wire that has strength and is suitably used in environments exposed to high temperatures. In addition, an insulated wire is the meaning including not only a narrowly-defined insulated wire which consists of a conductor and an insulation coating but what is called a cable which further covers one or more of the narrowly-defined insulated wires with a protective coating.

  This insulated wire can be produced by coating the resin composition of the present invention on a conductor to form an insulating coating, and further irradiating with ionizing radiation to crosslink the resin. The coating method can be performed by a method used in the production of a conventional insulated wire, for example, a method of extruding a resin composition on a conductor. As the conductor, it is possible to use a conductor such as a copper wire that constitutes an insulated wire or an insulated cable that has been conventionally used as wiring in an automobile.

  In addition to the insulated wire, the present invention further provides a resin tube comprising a resin composition formed into a tube shape. That is, the invention according to claim 6 is a heat shrinkable tube characterized in that the heat-resistant and flame-retardant resin composition according to any one of claims 1 to 4 is formed into a tube shape. is there. Examples of the resin tube of the present invention include a heat-shrinkable tube that shrinks in the inner diameter direction when heated at the melting point or higher of the resin composition.

  The resin composition of the present invention is a resin composition that balances mechanical strength such as insulation, heat resistance, oil resistance, flame retardancy, tensile properties and cut-through properties at a high level and has excellent cost performance. It is. In particular, the resin composition according to claim 1 is excellent in heat resistance, and the resin composition according to claim 2 is excellent in crimping processability. Therefore, the insulated wire of the present invention in which this resin composition is coated with insulation is excellent in the above-described characteristics, and is suitably used as a wire used in a high temperature environment such as wiring in an engine room of an automobile.

It is a schematic cross section which shows typically the measuring apparatus of a cut-through characteristic.

  Next, although the form for implementing this invention is demonstrated, the range of this invention is not limited to this form, A various change can be made in the range which does not impair the meaning of this invention.

  The tetrafluoroethylene-α-olefin copolymer is a copolymer of tetrafluoroethylene and an α-olefin such as polypropylene, but other copolymer components, for example, acrylic, within the range not detracting from the gist of the present invention. Acid esters, hexafluoropropylene, vinyl fluoride, vinylidene fluoride, perfluoroalkyl vinyl ether, chlorotrifluoroethylene, ethylene, butene-1, and glycidyl (meth) acrylate may be copolymerized.

  Copolymerization for producing this copolymer can be carried out by a known method, but as tetrafluoroethylene-propylene copolymers, those having various copolymerization ratios and molecular weights are commercially available. It may be used.

  The range of the copolymerization ratio and the molecular weight range of the tetrafluoroethylene-α-olefin copolymer are not particularly limited, but the copolymerization ratio is tetrafluoroethylene: α-olefin = 30: 70 to 70:30 (moles). The ratio is preferably in the range of 40:60 to 60:40. When the ratio of tetrafluoroethylene is less than 30%, heat resistance is lowered, and when it is more than 70%, flexibility tends to be impaired. Moreover, what has Mooney viscosity (ML1 + 10: 121 degreeC) in the range of 30-300 is preferable, and what is especially in the range of 50-200 is preferable. When the Mooney viscosity is less than 30, the cut-through characteristics are deteriorated. When the Mooney viscosity is more than 300, the appearance when extruded is deteriorated.

  The polyvinylidene fluoride is not mixed with the tetrafluoroethylene-α-olefin copolymer, but is mixed by copolymerizing vinylidene fluoride with hexafluoropropylene. The proportion of hexafluoropropylene in the vinylidene fluoride-hexafluoropropylene copolymer is preferably 3 to 20% by mass. When the ratio of hexafluoropropylene is less than 3% by mass, it is difficult to mix with the tetrafluoroethylene-α-olefin copolymer. On the other hand, if it exceeds 30% by mass, the oil resistance of the resin composition is lowered. The vinylidene fluoride-hexafluoropropylene copolymer generally has a melt flow rate (MFR) in the range of 1 to 100 as measured under conditions of a load of 12.5 kg and a temperature of 230 ° C. When the MFR is smaller than 1, the appearance when extruded is deteriorated. When the MFR is larger than 100, the cut-through characteristics are deteriorated.

  Random polypropylene is a polymer obtained by random copolymerization of propylene and ethylene, and usually the ethylene content is preferably 1 to 10% by weight or less. If it is less than 1% by weight, the crystallinity increases, and no cross-linking occurs even when irradiated with an electron beam. If it exceeds 10% by weight, the cut-through characteristics when the resin composition is made deteriorate. Moreover, you may use the terpolymer (terpolymer) which copolymerized butene-1 etc. further to ethylene. A melt flow rate (MFR) measured under the conditions of a load of 2.16 kg and a temperature of 190 ° C. is usually preferably in the range of 0.1 to 5. When the MFR is smaller than 0.1, the appearance when extruded is deteriorated, and when it is larger than 5, the cut-through characteristics are deteriorated.

  In addition to the above essential components, the resin composition of claim 1 is a halogen-free flame retardant such as magnesium hydroxide, aluminum hydroxide, calcium hydroxide, and a phosphorus flame retardant, as long as the spirit of the invention is not impaired. Addition of brominated flame retardants, chlorine-based flame retardants, antimony trioxide, phenolic, amine-based, sulfur-based and phosphorus-based antioxidants, lubricants such as stearic acid, fatty acid amide, silicone, polyethylene wax, and coloring pigments An agent may be added. In addition to the essential components described above, the resin composition of claim 2 includes phenolic, amine-based, sulfur-based and phosphorus-based antioxidants, stearic acid, fatty acids, and the like within the scope of the invention. You may add additives, such as lubricants, such as amide | amido, silicone, and polyethylene wax, and a color pigment. These additives may be added alone or in combination of two or more.

First, each material used in Examples and Comparative Examples is shown below.
Tetrafluoroethylene-propylene copolymer: Afras 150C (Asahi Glass Co., Ltd.)
Vinylidene fluoride-hexafluoropropylene copolymer: Kainer 2750 (manufactured by Arkema)
-Random polypropylene: Novatec PP EG6D (melting point 145 ° C) (manufactured by Nippon Polypro)
Block polypropylene: Nippon Polypro Novatec PP EC7 (melting point 160 ° C) (manufactured by Nippon Polypro)
・ Calcium carbonate: Softon 2200 (manufactured by Shiraishi Calcium Co., Ltd., heavy calcium carbonate)
Brominated flame retardant: SAYTEX BT-93 (manufactured by Albemarle Corporation, ethylene bistetrabromophthalimide)
Antimony trioxide: antimony trioxide MSA (manufactured by Yamanaka Sangyo Co., Ltd., average particle size 1 μm)

Examples 1-3 and Comparative Examples 1-7
The composition shown in Table 1 or 2 (expressed in parts by mass in the table) is kneaded with an open roll, pelletized with a pelletizer, then supplied to the wire coating extruder, and TA12 / 0 by the extruder. .18 conductor was extruded and coated with an insulation outer diameter of 1.5 mmφ (coating thickness: 0.375 mm). Thereafter, an electron beam of 100 kGy was irradiated with an electron beam irradiation apparatus, and an insulated wire covered with a crosslinked resin composition was manufactured. The insulated wires thus obtained were evaluated for tensile properties (tensile strength, tensile elongation), heat resistance, flame retardancy, insulating properties, oil resistance, and cut-through properties by the following methods. The results are shown in Tables 1 and 2.

[Tensile properties (tensile strength, tensile elongation)]
Tensile strength and tensile elongation were measured according to JIS C 3005 (1986). (Standard: Tensile strength ≧ 8 MPa, Tensile elongation ≧ 100%)

[Heat-resistant]
The insulated wire was left in a thermostat kept at 250 ° C. for 4 days and then taken out and measured for tensile strength and tensile elongation according to JIS C3005 (1986). Each rate was calculated. (Standard: Tensile strength residual ratio ≧ 85%, tensile elongation residual ratio ≧ 85%)

[Flame retardance]
UL1581 1080. In accordance with a vertical combustion test (UL VW-1 combustion test). Specifically, the insulated wire is held vertically, burned by a burner at an angle of 20 degrees, ignited for 15 seconds, and paused for 15 seconds 5 times. Was “pass”, and over 60 seconds was “fail”.

[Insulation]
The volume resistivity value (Ω · cm) was measured with a volume resistivity measuring device. (Standard: ≧ 10 to the 15th power)

[Oil resistance]
The insulated wire was immersed in IRM902 oil at 70 ° C. for 4 hours and then taken out. The tensile strength and the tensile elongation were measured according to JIS C3005 (1986). Calculated. (Standard: Tensile strength residual ratio ≧ 50%, tensile elongation residual ratio ≧ 50%)

[Cut-through characteristics]
Cut-through characteristics were measured using the measuring apparatus shown in FIG. In FIG. 1, 1 is a conductor, 2 is an insulation coating, and 3 is an insulated wire. A blade 4 (5 mil blade) having a 90 ° sharp edge (tip R = 0.125 mm, tip angle 90 °) is applied on the insulated wire 3, and a current value flowing between the conductor 1 and the sharp edge is measured. In the initial state, the conductor 1 and the sharp edge are insulated by the insulating coating 2 and no current flows. However, when the insulating coating 2 is cut by the blade 4, a current flows between the conductor 1 and the sharp edge. A load is applied to the blade 4 to measure the maximum load that the insulating coating 2 can withstand without being cut. The test atmosphere is a temperature of 23 ° C. and a humidity of 50% RH. A load of 150 N or more was used as a standard (acceptable level).

  From the results shown in Tables 1 and 2, the resin compositions of Examples 1 to 3 that satisfy the constituent requirements of the present invention have tensile properties, heat resistance, flame retardancy, insulation properties, oil resistance, and cut-through properties. It meets the criteria and shows that these properties are balanced at a high level. On the other hand, in the comparative example not satisfying the constituent requirements of the present invention, as described in the following 1) to 6), any one of tensile properties, heat resistance, flame retardancy, insulation properties, oil resistance, and cut-through properties is present. The criteria of the present invention are not met, and the problems of the present invention are not achieved.

1) When the mixing ratio of the tetrafluoroethylene-α-olefin copolymer is less than 40% by mass with respect to the total of the tetrafluoroethylene-α-olefin copolymer and the vinylidene fluoride-hexafluoropropylene copolymer (comparison) Example 7) has low tensile properties, particularly tensile elongation.
2) When the mixing ratio of the vinylidene fluoride-hexafluoropropylene copolymer is less than 20% by mass with respect to the total of the tetrafluoroethylene-α-olefin copolymer and the vinylidene fluoride-hexafluoropropylene copolymer (comparison) Example 6) has low oil resistance (residual tensile elongation).
3) When the mixing ratio of the random polypropylene is less than 10% by mass with respect to the total of the fluororubber composition and the random polypropylene (Comparative Example 3), the cut-through characteristics are low.
4) When the mixing ratio of the fluororubber composition is less than 60% by mass (Comparative Example 1, that is, when the mixing ratio of random polypropylene exceeds 40% by mass), the heat resistance is low.
5) When block polypropylene is used instead of random polypropylene (Comparative Example 5), tensile properties, heat resistance, oil resistance, and cut-through properties are low.
6) When the blending amount of the inorganic filler (heavy calcium carbonate) is less than 10 parts by mass (Comparative Example 2), the heat resistance and flame retardancy are low. On the other hand, when it exceeds 100 parts by mass (Comparative Example 4), the tensile property (tensile elongation) is low and the heat resistance (residual tensile elongation rate) is also low.

Examples 4-7
The composition shown in Table 3 (expressed in parts by mass in the table) was kneaded with an open roll, pelletized with a pelletizer, then supplied to an extruder for covering electric wires, and TA12 / 0.18 The conductor was extrusion coated with an insulation outer diameter of 1.5 mmφ (coating thickness: 0.375 mm). Thereafter, an electron beam of 100 kGy was irradiated with an electron beam irradiation apparatus, and an insulated wire covered with a crosslinked resin composition was manufactured. The insulated wires thus obtained were evaluated for tensile properties (tensile strength, tensile elongation), flame retardancy, insulating properties, oil resistance, and cut-through properties in the same manner as in Examples 1 to 3. . Moreover, the continuous heat-resistant temperature (heat resistance) and the crimping workability were measured by the following methods. The results are shown in Table 3.

[Continuous heat resistance temperature (heat resistance)]
The heat resistance was determined by the continuous heat resistance temperature of the automobile standard (JASO). Specifically, an aging test was performed at each temperature of 230 ° C., 250 ° C., 270 ° C., and 290 ° C., the time until the tensile elongation fell below 100% was determined, and the continuous heat resistant temperature was determined by performing an Arrhenius plot. .

[Crimping workability]
The end of the prototyped wire was crimped using a crimp terminal (model number SNAC3-A021T-M064) and a crimping machine (model number AP-K2N) manufactured by Nippon Crimp Terminal Manufacturing Co., Ltd., and the presence or absence of insulation cracks was observed with a microscope. Those with cracks were rejected, and those without cracks were accepted.

  From the results shown in Table 3, the resin compositions of Examples 4 and 5 that satisfy the constituent requirements of the invention of claim 2 and do not contain heavy calcium carbonate or the amount thereof is 5 parts by mass, Tensile properties, continuous heat-resistant temperature (heat resistance), flame retardancy, insulation, oil resistance and cut-through properties meet the standards, and crimping processability is also acceptable, and these properties are balanced at a high level. It has been shown. On the other hand, in Examples 6 and 7 in which the blending amount of heavy calcium carbonate is 10 parts by mass, the crimping processability does not meet the standards.

1. Conductor 2. 2. Insulation coating Insulated wire 4. (Sharp edge) blade

Claims (6)

  10 to 100 parts by mass of an inorganic filler is blended with 100 parts by mass of a mixture of a fluororubber composition composed of a tetrafluoroethylene-α-olefin copolymer and a vinylidene fluoride-hexafluoropropylene copolymer and random polypropylene. And a resin composition obtained by crosslinking the fluororubber composition and random polypropylene by irradiating with ionizing radiation, wherein the tetrafluoroethylene-α-olefin copolymer and vinylidene fluoride-hexafluoropropylene copolymer The mixing ratio with the coalescence is 80:20 to 40:60 (mass ratio), and the mixing ratio between the fluororubber composition and the random polypropylene is 60:40 to 90:10 (mass ratio). Heat resistant flame retardant resin composition.   Less than 10 parts by weight of an inorganic filler and 3 parts by weight per 100 parts by weight of a mixture of a fluororubber composition comprising a tetrafluoroethylene-α-olefin copolymer and a vinylidene fluoride-hexafluoropropylene copolymer and random polypropylene A resin composition obtained by blending ~ 20 parts by mass of a flame retardant and further irradiating ionizing radiation to crosslink the fluororubber composition and random polypropylene, the tetrafluoroethylene-α-olefin copolymer and The mixing ratio of vinylidene fluoride-hexafluoropropylene copolymer is 80: 20-40: 60 (mass ratio), and the mixing ratio of the fluororubber composition and random polypropylene is 60: 40-90: 10. A heat-resistant flame-retardant resin composition characterized by being (mass ratio).   The heat-resistant and flame-retardant resin composition according to claim 1 or 2, wherein the tetrafluoroethylene-α-olefin copolymer is a tetrafluoroethylene-propylene copolymer.   The heat-resistant flame-retardant resin composition according to any one of claims 1 to 3, wherein the inorganic filler is calcium carbonate.   The insulated wire which has a coating layer which consists of a heat-resistant flame-retardant resin composition of any one of Claim 1 thru | or 4 on a conductor.   A heat-shrinkable tube, wherein the heat-resistant and flame-retardant resin composition according to any one of claims 1 to 4 is formed into a tube shape.

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