JP4803476B2 - Heat resistant wire - Google Patents

Description

  The present invention relates to a heat resistant electric wire.

  Fluoropolymers (hereinafter also referred to as fluororesins) such as ethylene / tetrafluoroethylene copolymer (hereinafter also referred to as ETFE) are moldability, electrical insulation, water resistance, chemical resistance, and radiation resistance. Etc. In addition, since it has excellent mechanical strength, in particular, cut-through resistance, it has a wide range of applications as an insulating coating material for cables for robots, electric wires for devices such as computers, nuclear power generation, and electric wires for aircraft (for example, patent documents) 1).

  However, since ETFE is a copolymer of ethylene (hereinafter referred to as E) and tetrafluoroethylene (hereinafter referred to as TFE), it has higher heat resistance than perfluoro-based fluororesins such as polytetrafluoroethylene. The heat resistance of the electric wire is low and remains at a heat-resistant temperature of 150 ° C. defined in UL standard 1581 (see, for example, Non-Patent Document 1).

  As a method for improving the heat resistance of ETFE, it is effective to increase the content of repeating units based on TFE in ETFE to increase the fluorine content. However, when the content of the repeating unit based on TFE increases and the molar ratio of the repeating unit based on TFE / the repeating unit based on E exceeds 50/50, the melting point of ETFE decreases (for example, see Non-Patent Document 2). .) A fluororesin having a melting point of at least 232 ° C. is preferable in order to satisfy the standard of a heat resistant temperature of 200 ° C. defined by UL standard 1581. If the melting point is lower than this temperature, the coating material melts down during the heat resistance test of the electric wire, which is not preferable.

JP-A-5-314822 Hitachi Cable, Ltd., “Electric Wire and Cable Handbook (4th edition)”, page 80, Sankaido, 1984 Satokawa Takaomi, Fluorine resin handbook, 446 pages, Nikkan Kogyo Shimbun, 1990

  An object of this invention is to provide the heat resistant electric wire which is excellent in heat resistance.

The present invention relates to a repeating unit based on TFE (A), a repeating unit based on E (B), and CH ₂ ═CX (CF ₂ ) _n Y (where X and Y are each independently a hydrogen atom or a fluorine atom) , N is 1 or 2.), and the repeating unit (C) is based on the monomer represented by the following formula: repeating unit (A) / repeating unit (B) = 40/60 to 80/20 (molar ratio) Provided is a heat-resistant electric wire obtained by coating a conductor with a fluorinated copolymer of ((A) + (B)) / (C) = 99.9 / 0.1 to 85/15 (molar ratio). .

  The heat-resistant electric wire of the present invention is excellent in melt moldability, mechanical properties, electrical insulation and chemical resistance, and is excellent in heat resistance, particularly heat aging resistance at 232 ° C.

  In the fluorine-containing copolymer of the present invention, the repeating unit (A) based on TFE / the repeating unit (B) based on E = 40/60 to 80/20 (molar ratio), and 45/55 to 70/30 is Preferably, 50/50 to 65/35 is more preferable. When the molar ratio is smaller than this range, the heat resistance of the fluorinated copolymer and the heat-resistant electric wire is low. When the molar ratio is larger than this range, the mechanical strength, melt moldability, etc. of the fluorinated copolymer are low. When the molar ratio is within this range, the heat resistance, mechanical strength, and melt moldability are excellent. Moreover, it is ((A) + (B)) / (C) = 99.9 / 0.1-85 / 15 (molar ratio), 99.7 / 0.3-90 / 10 are preferable, and 99. 5 / 0.5 to 95/5 is more preferable. When the molar ratio of (C) is larger than this range, the heat resistance of the fluorinated copolymer and the heat-resistant electric wire is low, and when it is smaller than this range, the mechanical strength, melt moldability, etc. of the fluorinated copolymer are low. Within this range, the heat resistance, mechanical strength, and melt moldability are excellent.

As a monomer represented by CH ₂ = CX (CF ₂ ) _n Y in the present invention (hereinafter referred to as FAE), CH ₂ = CHCF ₃ , CH ₂ = CFCF ₃ , CH ₂ = CHCF ₂ H, CH ₂ = _{CFCF 2 H, CH 2 = CH} (CF 2) 2 F, CH 2 = CF (CF 2) 2 F, CH 2 = CH (CF 2) 2 H, the _{CH 2 = CF (CF 2)} 2 H and the like . Preferably, from the group consisting of CH ₂ ═CH (CF ₂ ) ₂ F, CH ₂ ═CF (CF ₂ ) ₂ F, CH ₂ ═CH (CF ₂ ) ₂ H and CH ₂ ═CF (CF ₂ ) ₂ H One or more selected. More preferably, CH ₂ ═CH (CF ₂ ) ₂ F.
The fluorine-containing copolymer in the present invention includes a repeating unit (A) based on TFE, a repeating unit (B) based on E, and a repeating unit (C) based on a monomer represented by CH ₂ ═CX (CF ₂ ) _n Y. Preferably it consists of.

The fluorine-containing copolymer in the present invention includes a repeating unit (A) based on TFE, a repeating unit (B) based on E, and a repeating unit (C) based on a monomer represented by CH ₂ ═CX (CF ₂ ) _n Y. In addition, it is also preferable to contain a repeating unit (D) based on other monomers.

  Other monomers include hexafluoropropylene (hereinafter referred to as HFP), fluoroolefins that do not have a hydrogen atom in an unsaturated group such as chlorotrifluoroethylene (except TFE), perfluoro (methyl vinyl ether), perfluoro (Propyl vinyl ether) (PPVE), perfluoro (alkyl vinyl ether) such as perfluoro (butyl vinyl ether), fluorine-containing alkyl vinyl ether having a hydrogen atom such as 2,2,2-trifluoroethyl trifluorovinyl ether, vinylidene fluoride (hereinafter, VDF)). Another monomer may be used individually by 1 type and may use 2 or more types together. The other monomer is preferably one or more selected from the group consisting of HFP, PPVE and VDF, more preferably HFP and PPVE.

  When the repeating unit (D) based on other monomer is contained, the content of (D) is 0.01 to 10 mol% with respect to ((A) + (B) + (C)). Preferably, 0.1-5 mol% is more preferable. When the content of (D) is in this range, the fluorine-containing copolymer is excellent in heat resistance and mechanical strength.

The volume flow rate (hereinafter referred to as Q value) measured at 297 ° C. of the fluorinated copolymer in the present invention is 1 to 500 mm ³ / sec. Q value is preferably 5 to 200 mm ³ / sec, more preferably 10 to 100 mm ³ / sec. The Q value is an index representing the melt fluidity of the fluorinated copolymer and is a measure of the molecular weight. A large Q value indicates a low molecular weight, and a small Q value indicates a high molecular weight. When the Q value is smaller than this range, extrusion molding becomes difficult, and when the Q value is larger, the mechanical strength of the fluorinated copolymer is lowered.

  There is no restriction | limiting in particular in the manufacturing method of the fluorine-containing copolymer in this invention, The polymerization method using the radical polymerization initiator generally used is used. Polymerization methods include bulk polymerization, solution polymerization using organic solvents such as fluorinated hydrocarbons, chlorinated hydrocarbons, fluorinated chlorohydrocarbons, alcohols, hydrocarbons, aqueous media, and appropriate organic solvents as required. Suspension polymerization, and emulsion polymerization using an aqueous medium and an emulsifier. In particular, solution polymerization is preferable. As polymerization conditions, the polymerization temperature is preferably 0 to 100 ° C, more preferably 20 to 90 ° C. The polymerization pressure is preferably from 0.1 to 10 MPa, more preferably from 0.5 to 3 MPa. The polymerization time is preferably 1 to 30 hours.

  A well-known technique can be used as a manufacturing method of the heat-resistant electric wire of the present invention. A method of coating a conductor with a fluorine-containing copolymer melted using an extruder, a method of winding a tape-shaped fluorine-containing copolymer around a conductor, and a tank in which a powder of the fluorine-containing copolymer is flowed Examples include a method of forming a coating layer by immersing the conductor and then heating and melting the powder adhering to the conductor. In particular, a method of coating the conductor with a fluorine-containing copolymer melted using an extruder is preferable.

  In addition, the conductor used as the core wire of the heat-resistant electric wire of the present invention is not particularly limited, and various plating wires such as copper, copper alloy, aluminum and aluminum alloy, tin plating, silver plating, nickel plating, stranded wire, superconductor, Examples thereof include plated wires for semiconductor element leads. The diameter of the conductor and the coating thickness of the fluorine-containing copolymer can be selected as appropriate. For example, in the UL standard Subject 758 STYLE 10109 (Extruded special copolymer of ethylene and tetrafluoroethylene insulated wire (ETFE)), the conductor thickness is determined according to the minimum thickness as shown in Table 1. In the table, AWG indicates American Wire Gage.

  The heat-resistant electric wire of the present invention may contain other components. Examples of other components include antioxidants, stabilizers, crosslinking agents, crosslinking aids, pigments, reinforcing fibers, processing aids, conductive fillers, foaming agents, foaming nucleating agents, and other fluoropolymers. .

The present invention will be described in detail using examples and comparative examples, but the present invention is not limited thereto. The composition, melting point and volume flow rate of the fluorinated copolymer were measured by the following methods. In addition, the tensile test of the heat-resistant electric wire and the evaluation of the heat resistance were performed according to UL Standard Subject 758 STYLE 10109 (Extracted Special Copolymer of Ethylene and Tetrafluorinated Insulated Wire (Referenced below)).
[Composition of fluorinated copolymer] It was determined by melt NMR analysis and fluorine content analysis.
[Melting Point of Fluorine-Containing Copolymer] Using a differential scanning calorimeter (DSC-220CU manufactured by Seiko Instruments Inc.), about 5 mg of a sample was heated from 100 ° C. to 300 ° C. at a rate of 10 ° C./min.

[Capacity flow rate (Q value) (mm ³ / sec)] Using a flow tester manufactured by Shimadzu Corporation, the fluorine-containing copolymer was pushed into an orifice having a diameter of 2.1 mm and a length of 8 mm under a load of 7 kg at a temperature of 297 ° C. The extrusion rate of the fluorine-containing copolymer when it is discharged is called the volume flow rate.
[Tensile test (MPa)] A wire of AWG20 coated with a fluorine-containing copolymer is cut to a length of about 100 mm, and the conductor is extracted to obtain a coating material sample. A tensile test was performed at a tensile rate of 50 mm / min at a room temperature of 25 mm between the tensile scores of the coating material samples. A tensile test is performed on five samples, and an average value of the obtained measurement values is obtained. A tensile strength of 34.5 MPa or more and an elongation of 200% or more are considered good.

[Evaluation of heat resistance] After the coating material sample was held in a gear oven maintained at 232 ° C for 7 days, a tensile test was performed at room temperature, and the tensile strength and elongation retention were calculated. A tensile strength retention of 80% or more and an elongation retention of 85% or more are good.
Moreover, in order to evaluate long-term heat aging resistance, the elongation of the coating material after 60 days at 232 ° C. was measured. If the elongation is 200% or more, the long-term heat resistance is better.

[Example 1]
The polymerization tank equipped with a stirrer with an internal volume of 94 liters was degassed, and 19.7 kg of water, 77.4 kg of 1-hydrotridecafluorohexane, 0.38 kg of pentane, CH ₂ = CHCF ₂ CF ₃ (below) , PFEE) is charged, and 11.06 kg of TFE and 0.38 kg of E are injected, the inside of the polymerization tank is heated to 50 ° C., and (F (CF) ₃ COO is used as a polymerization initiator solution. ₂ ) 1% by mass of 1,3-dichloro-1,1,2,2,3-pentafluoropropane (AK225cb manufactured by Asahi Glass Co., Ltd., hereinafter referred to as AK225cb) solution was charged with 350 mL, and polymerization was started.

  A monomer mixed gas having a molar ratio of TFE / E = 60/40 was continuously charged so that the pressure was kept constant during the polymerization. Further, in accordance with the charging of the monomer mixed gas, an amount of PFEE corresponding to 2.5 mol% with respect to the total number of moles of TFE and E was continuously charged. During the polymerization, the polymerization initiator solution was charged so that the polymerization rate became substantially constant. 4.5 hours after the start of the polymerization, when 11.0 kg of the monomer mixed gas was charged, the temperature inside the polymerization tank was lowered to room temperature and the pressure in the polymerization tank was purged to normal pressure. The total charged amount of the polymerization initiator solution was 2680 mL.

The slurry of the obtained fluorinated copolymer 1 was put into a 200 L granulation tank charged with 75 kg of water, and then heated to 105 ° C. while stirring to granulate while removing the solvent by distillation. The obtained granulated product was dried at 150 ° C. for 5 hours, whereby 11.4 kg of the granulated product 1 of the fluorinated copolymer 1 was obtained.
The composition of the fluorinated copolymer 1 was 58.2 / 41.8 / 2.3 in terms of the molar ratio of the repeating unit based on TFE / the repeating unit based on E / the repeating unit based on PFEE. The melting point of the fluorinated copolymer 1 was 243 ° C., and the Q value was 35 mm ³ / sec.

  The granulated product 1 was melt-extruded at a cylinder temperature of 260 to 280 ° C., a die temperature of 300 ° C., and a screw rotation speed of 30 rpm with a 20 mm extruder to produce pellets 1. Next, using a 30 mm extruder equipped with a crosshead die, the pellet 1 was melted and the conductor of the AWG 20 was coated to obtain a wire 1 having a coating material thickness of about 0.18 mm. The coating conditions were a cylinder temperature of 270 to 300 ° C., a die temperature of 320 ° C., a screw rotation speed of 20 rpm, and a linear speed of 30 m / min.

  The tensile strength of the covering material of the electric wire 1 was 53 Mpa, and the elongation was 504%. Regarding heat resistance at 232 ° C., the strength retention after 7 days was 83%, and the elongation retention was 107%. The elongation after 60 days was 325%, and the retention rate was 64%.

[Comparative Example 1]
The polymerization tank equipped with a stirrer with an internal volume of 94 liters was degassed, and 51.2 kg of 1-hydrotridecafluorohexane, 36.7 kg of AK225cb, CH ₂ = CH (CF ₂ ) ₄ F (hereinafter also referred to as PFBE) 0.47 kg of TFE), 13.13 kg of TFE and 0.70 kg of E were injected, the inside of the polymerization tank was heated to 66 ° C., and 0% of tert-butylperoxyisobutyrate was used as a polymerization initiator solution. 1 L of 1% by mass 1-hydrotridecafluorohexane solution was injected to initiate polymerization.

  A monomer mixed gas having a molar ratio of TFE / E = 54/46 was continuously charged so that the pressure was kept constant during the polymerization. Further, in accordance with the charging of the monomer mixed gas, an amount of PFBE corresponding to 1.5 mol% with respect to the total mole number of TFE and E was continuously charged. 7.0 hours after the start of polymerization, when 7.0 kg of the monomer mixed gas was charged, the temperature inside the polymerization tank was lowered to room temperature and the pressure in the polymerization tank was purged to normal pressure. The obtained slurry of fluorinated copolymer 2 was put into a 200 L granulation tank charged with 75 kg of water, and then granulated while distilling and removing the solvent by raising the temperature to 105 ° C. while stirring. The obtained granulated product was dried at 150 ° C. for 5 hours, whereby 27.2 kg of the granulated product of fluorinated copolymer 2 was obtained.

The composition of the fluorinated copolymer 2 is 53.1 / 46.9 / 1.6 in terms of the molar ratio of the repeating unit based on TFE / the repeating unit based on E / the repeating unit based on PFBE, and the melting point is 261 ° C. The Q value was 32 mm ³ / sec. In the same manner as in Example 1, an electric wire 2 covered with a fluorinated copolymer 2 was obtained. The tensile strength of the covering material of the electric wire 2 was 53.4 Mpa, and the elongation was 460%. The heat resistance at 232 ° C. was 80% strength retention after 7 days and 120% elongation retention. The elongation after 60 days was 45% and the retention rate was 9.7%.

[Comparative Example 2]
A polymerization tank equipped with a stirrer with an internal volume of 94 liters was degassed and charged with 19.7 kg of water, 47.8 kg of 1-hydrotridecafluorohexane, 23.3 kg of AK225cb, and 0.75 kg of PFBE, and TFE 7.95 kg of E and 0.28 kg of E were injected, the inside of the polymerization tank was heated to 65 ° C., and 0.5% by mass of tert-butylperoxyisobutyrate 1-hydrotridecafluorohexane was used as a polymerization initiator solution. 1 L of the solution was injected to initiate the polymerization.

  A monomer mixed gas having a molar ratio of TFE / E = 60/40 was continuously charged so that the pressure was kept constant during the polymerization. Further, in accordance with the charging of the monomer mixed gas, an amount of PFBE corresponding to 2.5 mol% with respect to the total number of moles of TFE and E was continuously charged. At the time when 11.0 kg of the monomer mixed gas was charged 6.2 hours after the start of polymerization, the temperature inside the polymerization tank was lowered to room temperature and the pressure in the polymerization tank was purged to normal pressure. The obtained slurry of fluorinated copolymer 3 was put into a 200 L granulation tank charged with 75 kg of water, and then granulated while distilling and removing the solvent by raising the temperature to 105 ° C. while stirring. The obtained granulated product was dried at 150 ° C. for 5 hours to obtain 12.0 kg of the granulated product 3 of the fluorinated copolymer 3.

The composition of the fluorinated copolymer 3 is 60.2 / 39.8 / 2.5 in terms of the molar ratio of the repeating unit based on TFE / the repeating unit based on E / the repeating unit based on PFBE, the melting point is 225 ° C., and the Q value. Was 38 mm ³ / sec. In the same manner as in Example 1, an electric wire 3 covered with the fluorine-containing copolymer 3 was obtained. The tensile strength of the covering material of the electric wire 3 was 49 MPa, and the elongation was 510%. In the heat resistance test at 232 ° C., the coating material melted and deformed in the gear oven and could not be used for the tensile test.

The electric wire coated with the fluorine-containing copolymer of the present invention is an electric machine such as a robot, an electric motor, a generator, or a transformer, an electric appliance for home use, a communication transmission device such as a telephone or a radio, a computer / data communication. Applicable to electric wires of electronic devices such as devices and terminal devices. It can also be applied to system configuration wires such as railway vehicles, automobile wires, aircraft wires, marine wires, buildings / factory trunk lines, power plants, petrochemical / steel plants.

Claims (5)

Tetrafluoroethylene-based repeating unit (A), ethylene-based repeating unit (B), and CH ₂ ═C H (CF ₂ ) _n Y (where Y is a hydrogen atom or a fluorine atom, and n is 1 or 2) The repeating unit (C) based on the monomer represented by the formula (1)), the repeating unit (A) / the repeating unit (B) = 40/60 to 80/20 (molar ratio), ((A) + (B)) / (C) = 99.9 / 0.1 to 95/5 (molar ratio), a heat-resistant electric wire obtained by coating a conductor with a coating material made of a fluorine-containing copolymer , The tensile strength retention after holding the coating material at 232 ° C. for 7 days is 80% or more, the elongation retention rate is 85%, and the elongation after 60 days at 232 ° C. is 200% or more. Heat-resistant electric wire . 2. The heat-resistant electric wire according to claim 1, wherein the fluorine-containing copolymer has a capacity flow rate measured at 297 ° C. of 1 to 500 mm ³ / sec. The CH ₂ = C H (CF ₂ ) _n Y is at least one selected from the group consisting of CH ₂ = CH (CF ₂ ) ₂ F and CH ₂ = CH (CF ₂ ) ₂ H. 2. The heat-resistant electric wire according to 2.   The fluorine-containing copolymer further contains a repeating unit (D) based on another monomer, and the content of the repeating unit (D) is ((A) + (B) + (C)) It is 0.01-10 mol%, The heat-resistant electric wire in any one of Claims 1-3.   The heat-resistant electric wire according to claim 4, wherein the other monomer is at least one selected from the group consisting of hexafluoropropylene, perfluoro (propyl vinyl ether) and vinylidene fluoride.