Resin composition for foam molding, foamed molded body, method for manufacturing a foamed molded body, foamed electric wire, and method for manufacturing a foamed electric wire

Abstract

The present invention provides a resin composition for foam molding that can sufficiently miniaturize air bubbles and has a good appearance, a foamed molded article, a method for manufacturing a foamed molded article, a foamed electric wire, and a method for manufacturing a foamed electric wire. [Solution] A resin composition for foam molding comprising a fluororesin (A) and a tetrapyrrole cyclic compound (B).

Description

[Technical Field]

[0001] This disclosure relates to a resin composition for foam molding, a foamed molded article, a method for manufacturing a foamed molded article, a foamed electric wire, and a method for manufacturing a foamed electric wire. [Background technology]

[0002] Fluoropolymers are widely used in a variety of applications due to their excellent heat resistance and chemical resistance.

[0003] Foam molding is a known method for reducing the weight and improving the electrical properties of fluororesins. In foam molding, fine bubbles can be formed by adding a substance that acts as a foaming nucleation site (foaming nucleation agent).

[0004] Due to the high molding temperature of fluororesins, the foaming nucleating agents that can be used are limited, and boron nitride is generally used (see, for example, Patent Documents 1-3). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 10-045931 [Patent Document 2] Japanese Patent Publication No. 2022-028640 [Patent Document 3] Japanese Patent Publication No. 2005-206745 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, boron nitride had room for improvement in that it could not sufficiently refine the bubbles.

[0007] In addition, Patent Document 1 discloses a method of refining bubbles by blending a salt such as perfluoroalkylsulfonic acid together with boron nitride. However, when a fluorosurfactant such as perfluoroalkylsulfonic acid is blended, the molten resin during molding may be plasticized, resulting in the generation of sparks and possible damage to the appearance, leaving room for improvement in this regard.

[0008] An object of the present disclosure is to provide a resin composition for foam molding, a foam molded body, a method for producing a foam molded body, a foam wire, and a method for producing a foam wire, which can sufficiently refine bubbles and have a good appearance.

Means for Solving the Problems

[0009] The present disclosure (1) is a resin composition for foam molding containing a fluororesin (A) and a tetrapyrrole-based cyclic compound (B).

[0010] The present disclosure (2) is the resin composition for foam molding according to the present disclosure (1), wherein the fluororesin (A) is a melt-moldable fluororesin.

[0011] The present disclosure (3) is the resin composition for foam molding according to the present disclosure (1) or (2), wherein the fluororesin (A) is at least one selected from the group consisting of a tetrafluoroethylene / hexafluoropropylene copolymer and a tetrafluoroethylene / perfluoro(alkyl vinyl ether) copolymer.

[0012] The present disclosure (4) is the resin composition for foam molding according to any one of the present disclosures (1) to (3), wherein the fluororesin (A) is a tetrafluoroethylene / hexafluoropropylene copolymer.

[0013] The present disclosure (j5) is the resin composition for foam molding according to any one of the present disclosures (1) to (4), wherein the fluororesin (A) is fluorinated.

[0014] Disclosure (6) is a foam molding resin composition according to any one of Disclosures (1) to (5), wherein the content of the fluororesin (A) is 80 to 99.99% by mass.

[0015] Disclosure (7) is a foam molding resin composition according to any one of Disclosures (1) to (6), wherein the content of the fluororesin (A) is 97% by mass or more and less than 99.85% by mass.

[0016] Disclosure (8) is a foam molding resin composition according to any of Disclosures (1) to (7) that substantially does not contain fluorine-based low molecular weight compounds.

[0017] Disclosure (9) is a foam molding resin composition according to any one of Disclosures (1) to (8) wherein the tetrapyrrole cyclic compound (B) has a phthalocyanine skeleton.

[0018] Disclosure (10) is a foam molding resin composition according to any one of Disclosures (1) to (9), wherein the tetrapyrrole cyclic compound (B) is a metal phthalocyanine.

[0019] The present disclosure (11) is a foam molding resin composition according to any one of the present disclosures (1) to (10), wherein the tetrapyrrole cyclic compound (B) is copper phthalocyanine.

[0020] The present disclosure (12) is a foam molding resin composition according to any one of the present disclosures (1) to (11), wherein the content of the tetrapyrrole cyclic compound (B) is 0.1 to 20 parts by mass per 100 parts by mass of the fluororesin (A).

[0021] Disclosure (13) is a foam molding resin composition according to any one of Disclosures (1) to (12), wherein the content of the tetrapyrrole cyclic compound (B) is 0.5 to 2.0 parts by mass per 100 parts by mass of the fluororesin (A).

[0022] Disclosure (14) is a foamed molded article formed using a foamed molding resin composition described in any of Disclosures (1) to (13).

[0023] This disclosure (15) is a method for producing a foamed molded article, which includes a step of foaming a foamed resin composition described in any of this disclosure (1) to (13).

[0024] The present disclosure (16) is a foamed electric wire having a conductor and a foamed insulating layer formed on the conductor using a foamed molding resin composition described in any of the present disclosures (1) to (13).

[0025] This disclosure (17) is a method for manufacturing a foamed electric wire, which includes the step of forming a foamed insulating layer on a conductor using a foamed molding resin composition described in any of this disclosure (1) to (13). [Effects of the Invention]

[0026] According to this disclosure, it is possible to provide a resin composition for foam molding that can sufficiently miniaturize air bubbles and has a good appearance, a foamed molded article, a method for manufacturing a foamed molded article, a foamed electric wire, and a method for manufacturing a foamed electric wire. [Modes for carrying out the invention]

[0027] The following provides a detailed explanation of this disclosure.

[0028] The foam molding resin composition of this disclosure comprises a fluororesin (A) and a tetrapyrrole cyclic compound (B).

[0029] In the foam molding resin composition of this disclosure, the tetrapyrrole cyclic compound (B) functions as a foaming nucleation agent, enabling the formation of finer bubbles compared to the case where boron nitride is used. This makes it possible to apply the composition to applications requiring thin molded products, such as thin electric wires. Furthermore, compared to the use of fluorine-based surfactants, it is possible to suppress the generation of sparks and reduce defects in appearance. This makes it possible to perform molding for long periods of time, such as in wire molding. Furthermore, not only is spark generation suppressed, but the surface roughness is reduced, resulting in improved electrical properties.

[0030] The fluororesin (A) can be any resin containing fluorine, but it is preferably a fluororesin that can be melt-molded. Examples of melt-mold fluororesins include tetrafluoroethylene (TFE) / hexafluoropropylene (HFP) copolymer [FEP], TFE / perfluoro(alkyl vinyl ether) (PAVE) copolymer [PFA], TFE / ethylene copolymer [ETFE], chlorotrifluoroethylene (CTFE) / ethylene copolymer [ECTFE], polyvinylidene fluoride [PVdF], polychlorotrifluoroethylene [PCTFE], TFE / vinylidene fluoride (VdF) copolymer [VT], polyvinyl fluoride [PVF], TFE / VdF / CTFE copolymer [VTC], TFE / ethylene / HFP copolymer, TFE / HFP / VdF copolymer, etc. One or more of these can be used.

[0031] Examples of the above-mentioned PAVEs include perfluoro(methyl vinyl ether) [PMVE], perfluoro(ethyl vinyl ether) [PEVE], and perfluoro(propyl vinyl ether) [PPVE]. Among these, PPVE is preferred. One or more of these can be used.

[0032] The fluororesin (A) may have polymerization units based on other monomers in an amount that does not impair the essential properties of each fluororesin. Examples of other monomers that can be appropriately selected include TFE, HFP, ethylene, propylene, perfluoro(alkyl vinyl ether), perfluoroalkylethylene, hydrofluoroolefin, fluoroalkylethylene, perfluoro(alkyl allyl ether), etc. One or more of these can be used. The perfluoroalkyl group constituting the other monomer is preferably one having 1 to 10 carbon atoms.

[0033] Other monomers may be monomers having polar groups. Examples of monomers having polar groups include nonfluorine monomers having hydroxyl groups such as hydroxyethyl vinyl ether, hydroxypropyl vinyl ether, hydroxybutyl vinyl ether, hydroxyisobutyl vinyl ether, hydroxycyclohexyl vinyl ether, and other hydroxyalkyl vinyl ethers; nonfluorine monomers having carboxyl groups such as acrylic acid, methacrylic acid, itaconic acid, succinic acid, fumaric acid, crotonic acid, maleic acid, citraconic acid, undecylenic acid, and acetylenedicarboxylic acid; itaconic anhydride (hereinafter also referred to as "IAH"), citraconic anhydride (hereinafter also referred to as "CAH"), 5-norbornene-2, Examples include nonfluorine monomers having acid anhydride residues such as 3-dicarboxylic acid anhydride (hereinafter also referred to as "NAH"), succinic anhydride, fumaric anhydride, and maleic anhydride; nonfluorine monomers having sulfo groups such as vinyl sulfonic acid; nonfluorine monomers having epoxy groups (glycidyl groups) such as glycidyl vinyl ether and glycidyl allyl ether; nonfluorine monomers having amino groups such as aminoalkyl vinyl ether and aminoalkyl allyl ether; nonfluorine monomers having amide groups such as (meth)acrylamide and methylolacrylamide; and nonfluorine monomers having nitrile groups such as acrylonitrile and methacrylonitrile.

[0034] Because of its excellent heat resistance, the fluororesin (A) is preferably at least one selected from the group consisting of TFE / HFP copolymers and TFE / PAVE copolymers, and more preferably a TFE / HFP copolymer. Furthermore, because it has superior electrical properties, it is also preferable to be a perfluororesin.

[0035] The TFE / HFP copolymer preferably has a TFE / HFP ratio of 80-97 / 3-20 by mass, and more preferably 84-92 / 8-16. The TFE / HFP copolymer may be a binary copolymer consisting of TFE and HFP, or it may be a terpolymer consisting of comonomers copolymerizable with TFE and HFP (for example, a TFE / HFP / PAVE copolymer). The TFE / HFP copolymer is also preferably a TFE / HFP / PAVE copolymer that contains polymerization units based on PAVE. The TFE / HFP / PAVE copolymer preferably has a mass ratio of 70-97 / 3-20 / 0.1-10 for TFE / HFP / PAVE, and more preferably 81-92 / 5-16 / 0.3-5.

[0036] The TFE / PAVE copolymer preferably has a TFE / PAVE ratio of 90-99 / 1-10 by mass, and more preferably 92-97 / 3-8.

[0037] The TFE / ethylene copolymer preferably has a TFE / ethylene molar ratio of 20-80 / 20-80, and more preferably 40-65 / 35-60. The TFE / ethylene copolymer may also contain other monomer components. In other words, the TFE / ethylene copolymer may be a binary copolymer consisting of TFE and ethylene, or it may be a tertiary copolymer consisting of TFE and a comonomer copolymerizable with ethylene (for example, a TFE / ethylene / HFP copolymer). The TFE / ethylene copolymer is also preferably a TFE / ethylene / HFP copolymer that contains polymerization units based on HFP. The TFE / ethylene / HFP copolymer is preferably composed of TFE / ethylene / HFP in a molar ratio of 40-65 / 30-60 / 0.5-20, and more preferably 40-65 / 30-60 / 0.5-10.

[0038] In this specification, "melt moldable" preferably means that the melt flow rate (MFR) is 1 to 100 g / 10 min. The MFR of fluororesin (A) is more preferably 5 to 70 g / 10 min, even more preferably 10 to 60 g / 10 min, which suppresses the generation of sparks and increases the foaming rate, and therefore even more preferably 15 to 50 g / 10 min, even more preferably 20 to 45 g / 10 min, and particularly preferably 30 to 45 g / 10 min. The above MFR values ​​were measured in accordance with ASTM D-1238 using a die with a diameter of 2.1 mm and a length of 8 mm, at 372°C and under a 5 kg load.

[0039] The fluororesin (A) may contain both a fluororesin that can be melt-molded and a fluororesin that cannot be melt-molded. If the fluororesin (A) contains a fluororesin that cannot be melt-molded, its content is preferably 0.001 to 3.0% by mass of the total amount of the fluororesin (A). In this specification, "unable to melt-mold" means that the above-mentioned MFR is less than 1 g / 10 min. Preferably, the above-mentioned MFR is 0.1 g / 10 min or less.

[0040] Examples of fluororesins that cannot be melt-molded include polytetrafluoroethylene (PTFE). Furthermore, fluororesins that can be melt-molded, such as FEP, PFA, ETFE, PCTFE, and PVDF, can also be used. One or more of these can be used. Among these, PTFE is preferred. Furthermore, FEP and similar materials are defined as fluororesins that cannot be melt-molded if the MFR is less than 1 g / 10 min, and fluororesins that can be melt-molded if the MFR is 1 g / 10 min or more.

[0041] In this disclosure, PTFE may be a tetrafluoroethylene [TFE] homopolymer, or a modified polytetrafluoroethylene [modified PTFE] obtained from TFE and a trace comonomer. TFE homopolymers are obtained by polymerizing tetrafluoroethylene (TFE) alone as the monomer. The trace comonomers in modified PTFE are not particularly limited as long as they are fluorine-containing compounds that can copolymerize with TFE, and include, for example, perfluoroolefins such as hexafluoropropene (HFP); perfluorovinyl ethers (PFVE) such as the various PAVEs mentioned above; fluorodioxoles, etc.; trifluoroethylene; vinylidene fluoride, etc. In modified PTFE, the content of trace monomer units derived from the above-mentioned trace monomers in relation to the total monomer units is usually in the range of 0.001 to 1.0 mass%. In this specification, "content of trace monomer units in total monomer units (mass %)" means the mass fraction (mass %) of trace monomers derived from the above-mentioned trace monomer units in relation to the total amount of monomers from which the "total monomer units" originate, i.e., the total amount of monomers that constitute the fluorine-containing polymer.

[0042] In terms of heat resistance and electrical properties, PTFE is preferably given a standard specific gravity [SSG] of 2.15 to 2.30, more preferably 2.25 or less, and even more preferably 2.22 or less. While PTFE with an SSG of less than 2.15 does not negate the effects of this disclosure, it is difficult to manufacture and impractical. SSG is a value measured based on the water displacement method in accordance with ASTM D4895-89. When the SSG of PTFE is low, a small amount of additive can increase its biaxial extensional viscosity. When the SSG is high, increasing the amount of additive will achieve the same effect.

[0043] PTFE can be prepared by known methods such as emulsion polymerization and suspension polymerization, but emulsion polymerization is preferred as the polymerization method. If PTFE aggregates are present in the foam molding resin composition of this disclosure, spark-out may occur frequently during wire coating molding, potentially worsening the defect rate. Therefore, the average primary particle size of PTFE is preferably 50 to 800 nm, and more preferably 50 to 500 nm. The average primary particle diameter of PTFE was determined by measuring the transmittance of 500 nm projection light per unit length for polymer latex diluted with water to a solid content of 0.22 mass%, and based on a calibration curve obtained by measuring the directional diameter in transmission electron microscope images beforehand, comparing it with the above transmittance.

[0044] Fluororesin (A) can be synthesized by polymerizing monomer components using conventional polymerization methods, such as emulsion polymerization, suspension polymerization, solution polymerization, bulk polymerization, and gas-phase polymerization. Chain transfer agents such as methanol may be used in the above polymerization reaction. Fluororesin (A) may also be produced by polymerization and isolation without the use of metal ion-containing reagents.

[0045] The fluororesin (A) is not particularly limited, but may have an end group such as -CF3 or -CF2H at at least one of the polymer main chain and polymer side chains, and is preferably one having an -CF3 end group. Fluororesins having these end groups are obtained by fluorination treatment. Unfluorinated fluororesins may have thermally and electrically unstable end groups such as -COOH, -CH2OH, -COF, and -CONH2 (hereinafter, such end groups are also referred to as "unstable end groups"). Such unstable end groups can be reduced by the fluorination treatment described above. It is preferable that fluororesin (A) has few or no such unstable end groups, and the total number of the four types of unstable end groups and the -CF2H end group is such that the carbon number is 1 × 10 6 It is more preferable that there be 50 or fewer per unit. If there are more than 50, molding defects may occur. It is more preferable that there be 20 or fewer of the above-mentioned unstable end groups, and even more preferable that there be 10 or fewer. In this specification, the number of unstable terminal groups is a value obtained from infrared absorption spectroscopy. It is also possible that the unstable terminal groups and -CF2H terminal groups are absent, and all are -CF3 terminal groups.

[0046] Fluorination treatment can be carried out by bringing an unfluorinated fluororesin into contact with a fluorine-containing compound. The fluorine-containing compound is not particularly limited, but examples include fluorine radical sources that generate fluorine radicals under fluorination treatment conditions. Examples of fluorine radical sources include F2 gas, CoF3, AgF2, UF6, OF2, N2F2, CF3OF, and halogenated fluorides (e.g., IF5, ClF3). One or more of these can be used. The fluorine radical source, such as F2 gas, may be at 100% concentration, but it is preferable to mix it with an inert gas and dilute it to 5-50% by mass, preferably 15-30% by mass, before use. Examples of the inert gas include nitrogen gas, helium gas, and argon gas, but nitrogen gas is preferred from an economic standpoint. The conditions for the fluorination treatment are not particularly limited, and the fluorine-containing compound may be brought into contact with the molten fluororesin. However, it is usually carried out at a temperature below the melting point of the fluororesin, preferably 20 to 220°C, and more preferably 100 to 200°C. The fluorination treatment is generally carried out for 1 to 30 hours, preferably 5 to 20 hours. The fluorination treatment preferably involves contacting an unfluorinated fluororesin with fluorine gas (F2 gas).

[0047] While the fluororesin (A) is not particularly limited, it is desirable that it has a melting point of 200°C or higher, a molding temperature of 250°C or higher, and a thermal decomposition temperature of 300°C or higher, in order to obtain a foamed molded article with excellent heat resistance and a wide continuous use temperature range. Furthermore, a melting point of 250°C or higher is more preferable, and 320°C or lower is preferable. A molding temperature of 300°C or higher is more preferable, and 450°C or lower is preferable. A thermal decomposition temperature of 350°C or higher is more preferable, and 400°C or higher is even more preferable. The upper limit for the melting point, molding temperature, and thermal decomposition temperature is 600°C or lower. In this specification, the melting point is the temperature measured by a differential scanning calorimeter (DSC), the molding temperature is a generally recommended temperature suitable for molding, at which the material is fluid and does not undergo resin degradation such as discoloration, and the thermal decomposition temperature is the temperature at which the material loses 1% of its weight when heated in air at 10°C / min, as measured by TG (thermal weight change measurement). However, weight loss due to the evaporation of contained water and crystal water observed between 100°C and 200°C is excluded. Fluidity means that the MFR is 0.0001 or higher at that temperature.

[0048] To minimize signal loss in communication lines, the dielectric constant of the fluororesin (A) is preferably 3.0 or less, more preferably 2.5 or less, even more preferably 2.3 or less, and most preferably 2.1 or less. The lower limit is 1.0 or higher. Similarly, the dielectric loss tangent is preferably 0.01 or less, more preferably 0.002 or less, even more preferably 0.001 or less, and most preferably 0.0005 or lower. The lower limit is 0.0001 or higher. The dielectric constant and dielectric loss tangent of the fluororesin (A) are measured by the empty cylinder resonator method at a frequency of 6 GHz.

[0049] The content of fluororesin (A) is preferably 80% by mass or more, more preferably 90% by mass or more. Even more preferably 95% by mass or more, and particularly preferably 97% by mass or more. The upper limit is preferably 99.99% by mass or less, more preferably 99.85% by mass or less, and even more preferably less than 99.85% by mass.

[0050] The foam molding resin composition of this disclosure may contain a resin other than fluororesin (A). Examples of resins other than fluororesin (A) include general-purpose resins such as polyethylene resin, polypropylene resin, vinyl chloride resin, and polystyrene resin; and engineering plastics such as nylon, polycarbonate, polyetheretherketone resin, polyphenylene sulfide resin, polyaryletherketone (PAEK), polyetherketoneketone (PEKK), polyetherketone (PEK), polyetheretherketoneketone (PEEKK), etc., polyethersulfone (PES), liquid crystal polymer (LCP), polysulfone (PSF), amorphous polyarylate (PAR), polyethernitrile (PEN), thermoplastic polyimide (TPI), polyimide (PI), polyetherimide (PEI), and polyamideimide (PAI). One or more of these can be used.

[0051] The content of resins other than fluororesin (A) is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 1% by mass or less. The lower limit is not particularly limited and may be 0% by mass.

[0052] The foam molding resin composition of this disclosure contains a tetrapyrrole cyclic compound (B) as a foaming nucleating agent.

[0053] Tetrapyrrole cyclic compounds (B) are classified into three types based on their skeleton: phthalocyanines, chlorines, and bacteriochlorines. They can also form complexes with metals, such as copper, iron, and magnesium.

[0054] In terms of good function as a foaming nucleating agent, the tetrapyrrole cyclic compound (B) is preferably one having a phthalocyanine skeleton, more preferably a metallic phthalocyanine, and even more preferably a copper phthalocyanine.

[0055] It is preferable that the tetrapyrrole cyclic compound (B) does not decompose at the molding temperature during foam molding, and is insoluble and non-melted in the fluororesin (A). In other words, it is preferable that the tetrapyrrole cyclic compound (B) is solid in the foam molding resin composition of this disclosure when it is foam molded. This allows it to fully exhibit its function as a foam nucleating agent. The fact that the tetrapyrrole cyclic compound (B) satisfies this condition can be confirmed by observing, using a polarizing microscope equipped with a hot stage, whether the tetrapyrrole cyclic compound (B) remains in a solid state when heated to a predetermined temperature.

[0056] The tetrapyrrole cyclic compound (B) preferably has a crystallite size greater than 100 Å, more preferably greater than 140 Å, and even more preferably greater than 200 Å, as determined by X-ray diffraction (XRD). This allows for the formation of an ideal crystal lattice with minimal strain, promoting bubble formation. The upper limit of the crystallite size is preferably 10,000 Å or less, more preferably 5,000 Å or less, and even more preferably 1,000 Å or less. XRD is performed using a Rigaku Smart Lab X-ray diffractometer and Smart Lab Studio II measurement and analysis software to measure the powder. A CuKα X-ray source with a wavelength of 1.54 Å is used, and the diffraction angle (2θ) is set to 5° to 90°. The crystallite size is calculated from the widest full width at half maximum of the obtained diffraction peak using Scherrer's formula. D = K × λ / (β × cosθ) ···Scherrer's formula D: Crystallite size (Å) K: Scherrer constant λ: X-ray wavelength (Å) β: Full width at half maximum (rad) of the diffraction peak θ: Half of the diffraction angle (rad) The Scherrer constant (K) is assumed to be 0.94, and the X-ray wavelength (λ) is assumed to be 1.5418. If the obtained diffraction spectrum does not have diffraction peaks originating from the crystal structure, it is assumed that it does not have a crystal structure.

[0057] The tetrapyrrole cyclic compound (B) preferably has a volatilization amount of 7.0% by mass or less, more preferably 5.0% by mass or less, even more preferably 3.0% by mass or less, and particularly preferably 1.0% by mass or less at 330°C. This suppresses the generation of deposits (eye deposits) that cause molding defects, enabling long-term molding such as wire molding. The lower limit is not particularly limited and may be 0% by mass. Volatilization is calculated by measuring the mass decrease when a sample is held in an electric furnace at 330°C for 1 hour, and then multiplying the mass decrease by the original mass by 100.

[0058] From the viewpoint of forming more uniform bubbles, it is preferable that the tetrapyrrole-based cyclic compound (B) is dispersed in the fluororesin (A) at a center-of-centimeter distance of 5.0 μm or less. The upper limit of the center-of-centimeter distance is more preferably 3.0 μm or less, even more preferably 2.0 μm or less, and the lower limit is preferably 0.01 μm or more, more preferably 0.1 μm or more, and even more preferably 0.5 μm or more.

[0059] Because it can form more uniform bubbles, the tetrapyrrole cyclic compound (B) is used in fluororesin (A) at a density of 15,000 cells / mm³. 2 It is preferable that the particles are dispersed as described above. The lower limit of the density is more preferably 30,000 particles / mm³. 2 More preferably 120,000 pieces / mm 2 The above applies, with a preferred upper limit of 10,000,000 pieces / mm². 2 More preferably, 5,000,000 pieces / mm 2 More preferably, 1,000,000 pieces / mm 2 The following applies:

[0060] From the viewpoint of forming more uniform bubbles, it is preferable that the tetrapyrrole cyclic compound (B) is dispersed in the fluororesin (A) with a particle size of 4.0 μm or less. The upper limit of the particle size is more preferably 3.0 μm or less, even more preferably 2.0 μm or less, and the lower limit is preferably 0.001 μm or more, more preferably 0.01 μm or more, and even more preferably 0.1 μm or more.

[0061] The dispersion state (center-of-centimeter distance, density, and particle size) of the tetrapyrrole cyclic compound (B) in the fluororesin (A) is calculated by taking cross-sectional images of the resin composition containing the fluororesin (A) and the tetrapyrrole cyclic compound (B) at 150x magnification using a laser microscope (Keyence's shape analysis laser microscope (VK-X1000)) and processing the images. The center-of-centimeter distance and particle size are the average values ​​of 100 samples.

[0062] The melting temperature (melting point) of the tetrapyrrole cyclic compound (B) is preferably 300°C or higher, more preferably 320°C or higher, and even more preferably 350°C or higher. Within this range, it is less likely to melt even at the molding temperature during foam molding, and can fully exhibit its function as a foaming nucleating agent. There is no particular upper limit, but it is preferably 1000°C or lower.

[0063] The thermal decomposition temperature of the tetrapyrrole cyclic compound (B) is preferably 270°C or higher, more preferably 320°C or higher, and even more preferably 350°C or higher. Within this range, decomposition is less likely even at the molding temperature during foam molding. Therefore, adverse effects due to the decomposition of the tetrapyrrole cyclic compound (B) (e.g., deterioration of electrical properties, bubble rupture, and insulation breakage during wire molding) can be suppressed. There is no particular upper limit, but 1000°C or lower is preferred.

[0064] The melting temperature (melting point) and thermal decomposition temperature of the tetrapyrrole cyclic compound (B) can be measured using the same method as described above for the fluororesin (A).

[0065] In the foam molding resin composition of this disclosure, the content of the tetrapyrrole cyclic compound (B) is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, even more preferably 0.5 parts by mass or more, and preferably 20 parts by mass or less, more preferably 5.0 parts by mass or less, and even more preferably 2.0 parts by mass or less, per 100 parts by mass of fluororesin (A). If the content of the tetrapyrrole cyclic compound (B) is too low, the effect of adding the tetrapyrrole cyclic compound (B) may not be sufficiently obtained, and if it is too high, the manufacturing cost may increase.

[0066] The foam molding resin composition of this disclosure may contain foaming nucleating agents other than the tetrapyrrole cyclic compound (B). Examples of foaming nucleating agents other than tetrapyrrole cyclic compounds (B) include boron nitride, sodium 2,2'-methylenebis(4,6-di-t-butylphenyl) phosphate, barium fluorooctanesulfonate, barium bisphenol phosphate diester, N,N'-dicyclohexyl-2,6-naphthalenedicarboxamide, sodium benzenephosphonate, 2,6-naphthalenedicarboxylic acid, 1,3:2,4-bis-O-(4-methylbenzylidene)-D-sorbitol, N,N'-dioctadecylisophthalamide, sodium benzoate, sodium bis(4-nitrophenyl) phosphate, triaminobenzene derivatives, 1,3,5-tris(2,2-dimethylpropionylamino)benzene, pigment red 254, talc, sodium binaphthyl phosphate, barium t-butyl-binaphthyl phosphate, rosin metal salts, condensed phosphate esters, and the like. Other examples include sulfonic acids, sulfonates, phosphonic acids, phosphoates, zeolites, ADCA (azodicarbonamide), DPT (N,N'-dinitropentamethylenetetramine), and OBSH (4,4'-oxybisbenzenesulfonyl hydrazide). One or more of these can be used.

[0067] The foam molding resin composition of this disclosure may further contain a polyatomic anion-containing inorganic salt, to the extent that it does not impair the effects of this disclosure. Examples of polyatomic anion-containing inorganic salts include those disclosed in U.S. Patent No. 4,764,538.

[0068] The foam molding resin composition of this disclosure may contain conventionally known fillers to the extent that they do not impair the effects of this disclosure.

[0069] Examples of fillers include graphite, carbon fiber, coke, silica, zinc oxide, magnesium oxide, magnesium sulfate, tin oxide, antimony oxide, calcium carbonate, magnesium carbonate, magnesium hydroxide, glass, talc, mica, aluminum nitride, calcium phosphate, sericite, diatomaceous earth, silicon nitride, fine silica, fumed silica, alumina, zirconia, quartz powder, kaolin, bentonite, and titanium oxide. One or more of these can be used. The shape of the filler is not particularly limited and can be fibrous, needle-shaped, columnar, whisker-shaped, plate-shaped, layered, flaky, balloon-shaped, porous, chopped fiber-shaped, powder-shaped, granular, or bead-shaped. Note that the filler is different from boron nitride, etc., mentioned as a foaming nucleating agent.

[0070] The foam molding resin composition of this disclosure may further contain other components such as additives. Examples of other components include fillers such as glass fibers, glass powder, asbestos fibers, cellulose fibers, and carbon fibers, as well as reinforcing agents, stabilizers, lubricants, pigments, flame retardants, and other additives.

[0071] If the resin contains a large amount of fluorine-based low molecular weight compounds, the molten resin may become plasticized during molding, resulting in increased sparking. Therefore, it is preferable that the foam molding resin composition of this disclosure is substantially free of fluorine-based low molecular weight compounds. Furthermore, "effectively free of fluorinated low-molecular-weight compounds" means that the content of fluorinated low-molecular-weight compounds is 10 ppm by mass or less.

[0072] The fluorine-based low molecular weight compound is not particularly limited, and examples thereof include fluorine-based compounds having a molecular weight of 1000 or less. Specifically, perfluoroalkyl acids, perfluorosulfonic acids, etc. can be mentioned. More specifically, C8F 17 COOH and its salts, C7F 15 COOH and its salts, C6F 13 COOH and its salts, C8F 17 SO3H and its salts, C6F 13 SO3H and its salts, C4F9SO3H and its salts, C8F 17 CH2CH2-SO3H and its salts, C6F 13 CH2CH2-SO3H and its salts, C8F 17 CH2CH2OH, C6F 13 CH2CH2OH, etc. can be mentioned, and more specifically, {F(CF2)6CH2CH2SO3}2Ba can be mentioned.

[0073] The content of the fluorine-based low molecular weight compound can be analyzed by the following method: The sample is pulverized by cryogenic pulverization, the prepared powder is dispersed in methanol, and ultrasonic waves are applied at 60 °C for 2 hours for extraction. The value quantified by a liquid chromatograph-mass spectrometer (LC-MS / MS) for the extract is taken as the content.

[0074] The melt flow rate (MFR) of the resin composition for foam molding of the present disclosure is preferably 1 to 100 g / 10 min. More preferably, it is 5 to 70 g / 10 min, still more preferably, it is 10 to 60 g / 10 min. Since the generation of sparks can be suppressed and the foaming ratio increases, even more preferably, it is 15 to 50 g / 10 min, even more preferably, it is 20 to 45 g / 10 min, and particularly preferably, it is about 30 to 45 g / 10 min. The above MFR is a value measured at a load of 5 kg and 372 °C using a die with a diameter of 2.1 mm and a length of 8 mm in accordance with ASTM D-1238.

[0075] To reduce signal loss in communication lines, the dielectric constant of the foam molding resin composition of this disclosure is preferably 3.0 or less, more preferably 2.5 or less, even more preferably 2.3 or less, and most preferably 2.1 or less. The lower limit is 1.0 or more. Similarly, the dielectric loss tangent is preferably 0.01 or less, more preferably 0.002 or less, even more preferably 0.001 or less, and most preferably 0.0005 or less. The lower limit is 0.0001 or more. The dielectric constant and dielectric loss tangent of the foam molding resin composition of this disclosure are measured using the resin composition before foam molding by an empty cylinder resonator method at a frequency of 6 GHz.

[0076] The foam molding resin composition of this disclosure can be suitably used as a foaming composition, and in particular, it can be suitably used as a wire coating composition for forming a coating layer for electric wires.

[0077] The method for manufacturing a foamed molded article according to the present disclosure includes a step of foaming and molding a foamed molding resin composition according to the present disclosure. Furthermore, the foamed molded article of this disclosure is formed using the foamed molding resin composition of this disclosure.

[0078] The method for foam molding the foam molding resin composition of the present disclosure is not particularly limited, and conventionally known methods can be used. For example, one method involves feeding the foam molding resin composition of the present disclosure into a screw extruder designed for foaming operations and using a continuous gas extrusion method.

[0079] The gas used in the gas extrusion method can be, for example, chlorodifluoromethane, nitrogen, carbon dioxide, or a mixture of the above gases. It may be introduced into the molten resin in the extruder as a pressurized gas, or it may be generated by mixing a chemical blowing agent into the molten resin. The introduced gas dissolves into the molten resin in the extruder.

[0080] The gas dissolved in the resin escapes from the molten material as the pressure of the molten material suddenly drops as it exits the extrusion die. The extruded material is then cooled and solidified, for example, by introducing it into water.

[0081] The foamed molded body of this disclosure has a low dielectric constant, exhibits stable capacitance, and is lightweight, so it can be used as a coating material as described later to obtain a shape with stable dimensions such as wire diameter and thickness.

[0082] The total volume of bubbles in the foamed molded body of this disclosure can be appropriately adjusted according to the application, for example, by adjusting the amount of gas inserted into the extruder, or by selecting the type of gas to be dissolved.

[0083] The foamed molded articles of this disclosure are obtained as molded articles formed according to their intended use during extrusion from the extruder. The molding method is not particularly limited as long as it is heat melt molding, and examples include extrusion foam molding, injection foam molding, and die foam molding.

[0084] The shape of the foamed molded body of this disclosure is not particularly limited and can be in various shapes, such as a covering material for foamed electric wires, a filament-shaped, sheet-shaped, film-shaped, rod-shaped, or pipe-shaped material for wires, etc. The foamed molded body can be used, for example, as an electrical insulating material, a heat insulating material, a sound insulating material, a lightweight structural material such as a floating material, or a cushioning material such as a cushion. Furthermore, the foamed molded body can be used particularly suitably as a covering material for foamed electric wires. The resulting foamed molded article contains a molten and solidified body of the foamed molding resin composition of this disclosure and bubbles, and it is preferable that the bubbles are uniformly distributed in the molten and solidified body. The bubble size is not limited, but is preferably 60 μm or less, and more preferably 30 μm or less. Furthermore, it is preferable that the bubble size is 0.1 μm or more. The foaming ratio of the foamed molded article is not particularly limited, but is preferably 20% or more. The upper limit of the foaming ratio is not particularly limited, but is, for example, 80%.

[0085] The bubbles in the foamed molded article of this disclosure may be open or closed, but closed bubbles are preferable. Being closed bubbles has the advantage of strong repulsive force against external pressure, excellent rigidity, shock absorption, and processability, and also prevents moisture from entering the interior. Closed cells can be formed by conventionally known methods in addition to the heat melt molding described above.

[0086] The foamed molded article of this disclosure is in a foamed state that is advantageous for reducing dielectric constant, and can therefore be used as a correlated insulator for, for example, an insulating layer for electric wires, an insulating layer for semiconductor package substrates, an insulating layer for transformers, an insulating layer for circuit boards, an insulating layer for motors, an insulating layer for reactors, an insulating layer for transistors, an insulating layer for printed circuit boards, an insulating layer for semiconductor devices, and an insulating layer for electronic components. In particular, it can be suitably used as an insulating layer (coating layer) for electric wires.

[0087] The method for manufacturing a foamed electric wire according to the present disclosure includes the step of forming a foamed insulating layer (coating layer) on a conductor using the foam molding resin composition according to the present disclosure. Furthermore, the foamed electric wire of this disclosure comprises a conductor and a foamed insulating layer (coating layer) formed on the conductor using the foam molding resin composition of this disclosure.

[0088] The method for forming a foamed insulating layer (coating layer) on a conductor using the foamed molding resin composition of this disclosure is not particularly limited. For example, a method can be used in which a gas soluble in molten fluororesin (molten resin) is used, the foamed molding composition of this disclosure is introduced into a screw extruder designed for foaming operations, and a continuous gas injection method is used. The gas used is the same as the gas used in the manufacturing method of the foamed molded article.

[0089] The foamed electric wire of this disclosure has a foamed insulating layer in a foamed state that is advantageous for achieving a low dielectric constant, and therefore can suppress signal attenuation compared to conventional electric wires.

[0090] For the conductor (core wire), materials such as copper, aluminum, and other metal conductors, or carbon can be used. Furthermore, even if a single material is used, the surface may be plated with silver, tin, or other materials. The conductor is preferably 0.02 to 3 mm in diameter. More preferably, the conductor diameter is 0.04 mm or more, even more preferably 0.05 mm or more, and particularly preferably 0.1 mm or more. More preferably, the conductor diameter is 2 mm or less. The conductor may be a single wire or a stranded wire made by twisting multiple conductors together. The shape of the conductor is not particularly limited, and examples include flat shapes and rectangular wires.

[0091] Specific examples of conductors (core wires) include, for example, AWG-46 (solid copper wire with a diameter of 40 micrometers), AWG-42 (solid copper wire with a diameter of 64 micrometers), AWG-36 (solid copper wire with a diameter of 127 micrometers, made by twisting together seven copper wires with a diameter of 51 micrometers, resulting in a total wire size of 153 micrometers), AWG-30 (solid copper wire with a diameter of 254 micrometers, made by twisting together seven copper wires with a diameter of 102 micrometers, resulting in a total wire size of 306 micrometers), AWG-27 ​​(solid copper wire with a diameter of 361 micrometers), AWG-26 (solid copper wire with a diameter of 404 micrometers), AWG-24 (solid copper wire with a diameter of 510 micrometers), and AWG-22 (solid copper wire with a diameter of 635 micrometers).

[0092] The thickness of the foamed insulating layer (coating layer) is preferably 0.01 to 3.0 mm, and also preferably 2.0 mm or less.

[0093] The surface roughness of the foamed insulating layer (coating layer) is preferably 9.0 μm or less, more preferably 8.0 μm or less, and even more preferably 7.0 μm or less. The lower limit is not particularly limited, but is usually 1.0 μm or more. The surface roughness is obtained by measuring the surface of the foamed wire using a laser microscope (VK-X1000) manufactured by Keyence Corporation, correcting the obtained image data using quadratic surface correction to specify the range of the wire, and then calculating the surface roughness at 500 × 2000 μm.

[0094] The number of sparks in the foamed insulating layer (coating layer) is 200 / 10 4 m or less is preferred, 80 pieces / 10 4 m or less is more preferable, 30 pieces / 10 4 m or less is even more preferable. The lower limit is not particularly limited, 0 / 10 4 m. The number of sparks is a value obtained by measuring it at a voltage of 1500V using a Beta LaserMike Sparktester HFS1220.

[0095] The foamed wires of this disclosure can be used as cables for connecting computers and their peripherals, cables for high-capacity video and audio high-speed communication, cables for connecting servers in data centers, for example, LAN cables, USB cables, Lightning cables, Thunderbolt cables, CATV cables, HDMI® cables, QSFP cables, aerospace cables, underground power transmission cables, submarine power cables, high-voltage cables, superconducting cables, wrapping wires, automotive cables, wire harnesses and electrical components, robot and FA cables, OA equipment cables, information equipment cables (fiber optic cables, audio cables, etc.), internal wiring for communication base stations, high-current internal wiring (inverters, power conditioners, battery systems, etc.), internal wiring for electronic equipment, small electronic equipment and mobile wiring, movable part wiring, internal wiring for electrical equipment, internal wiring for measuring instruments, power cables (for construction, wind / solar power generation, etc.), control and instrumentation wiring cables, motor cables, etc.

[0096] The foamed electric wires of this disclosure may have a two-layer structure (skin-foam) in which a non-foamed layer is inserted between the core wire and the covering material, a two-layer structure (foam-skin) in which a non-foamed layer is covered on the outer layer, or even a three-layer structure (skin-foam-skin) in which a non-foamed layer is covered on the outer layer of a skin-foam structure. The non-foaming layer is not particularly limited and may be a resin layer made of TFE / HFP copolymer, TFE / PAVE copolymer, TFE / ethylene copolymer, vinylidene fluoride polymer, polyolefin resin such as polyethylene [PE], or polyvinyl chloride [PVC].

[0097] Although embodiments have been described above, it should be understood that various modifications to the form and details are possible without departing from the spirit and scope of the claims. [Examples]

[0098] The present disclosure will now be further described with reference to examples, but the present disclosure is not limited to these examples.

[0099] The various properties described herein were measured by the following method. (Measurement of unstable terminal cardinal) The pellets were rolled using a hydraulic press to produce a film approximately 0.3 mm thick, and this film was analyzed using an FT-IR Spectrometer 1760X (manufactured by Perkin-Elmer). Obtain the difference spectrum from a standard sample (a sample that has been sufficiently fluorinated until there is no substantial difference in the spectrum), read the absorbance of each peak, and calculate the difference according to the following formula for a sample with 1 × 10 carbon atoms. 6 The number of unstable terminal groups per molecule was calculated. 1 × 10⁻¹⁶ carbon atoms 6 Number of unstable terminal groups per unit = (I × K) / t (I: absorbance, K: correction factor, t: film thickness (unit: mm)) The correction factor (K) for each unstable terminal group is as follows: -COF (1884cm) -1 )···405 -COOH (1813cm) -1 , 1775cm -1 )···455 -COOCH3 (1795cm) -1 )···355 -CONH2 (3438cm) -1 )···480 -CH2OH (3648cm) -1 )···2325

[0100] (Measurement of -CF2H terminal bands) Using a nuclear magnetic resonance spectrometer AC300 (manufactured by Bruker-Biospin), the measurement temperature was set to the melting point of fluororesin (A) + 20°C. 19 The results were obtained by performing 1F-NMR measurements and comparing the integral values ​​of the peak originating from the presence of the -CF2H group with the integral values ​​of other peaks.

[0101] (SSG) Measurements were taken based on the water displacement method in accordance with ASTM D4895-89.

[0102] (Melting point) The melting point was defined as the temperature corresponding to the peak measured using a DSC (RDC220 manufactured by Seiko Electronics Co., Ltd.) at a heating rate of 10°C / min.

[0103] (pyrolysis temperature) The temperature at which the sample lost 1% of its weight was heated in air at 10°C / min was measured using a TG (Ground Test).

[0104] (MFR) In accordance with ASTM D-1238, the values ​​were measured using a KAYENESS Melt Indexer Series 4000 (manufactured by Yasuda Seiki Co., Ltd.) with a die measuring 2.1 mm in diameter and 8 mm in length, at 372°C and under a 5 kg load.

[0105] The examples and comparative examples were prepared using the following methods.

[0106] (Preparation of FEP pellets) Fluorinated FEP pellets were prepared by the same method as in Example 1 of Japanese Patent Publication No. 2017-128119. The obtained pellets (TFE / HFP / PPVE copolymer) had a TFE / HFP / PPVE ratio of 87.9 / 11.1 / 1.0 (mass ratio), a melting point of 261°C, a MFR of 38 g / 10 min, and a total number of unstable end groups and -CF2H end groups: 1 carbon atom × 10¹⁶ carbon atoms. 6 The result was 0 per unit.

[0107] (Pre-mixed pellets for wire molding (Step 1)) Masterbatch pellets were prepared by mixing FEP pellets (MFR: 38g / 10min) and additives in a twin-screw extruder with the cylinder and die sections set to the temperatures shown in Table 1. The additive concentration in the masterbatch pellets was approximately 2 to 5 times that of the additive concentration in the premix pellets. The obtained masterbatch pellets and FEP pellets were mixed in a mixer to prepare premix pellets with the desired additive concentration.

[0108] [Table 1]

[0109] (Evaluation of foamed wire molding (Process 2)) For foam molding, we used an extruder and system manufactured by Seisei Seisakusho Co., Ltd., a gas injection nozzle manufactured by Micodia Co., Ltd., and a crosshead manufactured by Unitech Co., Ltd. The configuration and conditions of the extruder are shown in Table 2, and the extruder temperature is shown in Table 3. Nitrogen gas was introduced as a foaming agent into the melting and mixing section of this foam molding extruder, and the premixed pellets (composition) prepared above were supplied and extruded to form a foamed wire. A foamed wire was obtained by covering a Φ0.30 mm core wire with a foamed molded body such that the outer diameter was 0.80 mm and the capacitance was 86 pf / m. The outer diameter of the wire was measured using a LASER MICRO DIAMETER LDM-303H-XY (manufactured by Takikawa Engineering Co., Ltd.). Capacitance was measured using a CAPAC300 19C (manufactured by Zumbach).

[0110] [Table 2]

[0111] [Table 3]

[0112] (Bubble size) SEM images were taken of the cross-section of the foamed wire, and the equivalent circular diameter of each bubble was calculated using image processing. The average of 100 bubbles was then used as the bubble size.

[0113] (Foaming rate) It was calculated as (specific gravity of fluororesin - specific gravity of foamed molded product) / (specific gravity of fluororesin) × 100.

[0114] (Smoke) Visually, the upper part of the resin discharge port of the extruder die was observed to check for the presence or absence of volatile components.

[0115] (Eye discharge) Visually inspected the resin discharge port portion of the extruder die to check for any deposits.

[0116] (Surface condition) The degree of roughness (protrusions) felt when touching the surface of the foamed wire was evaluated according to the following criteria. Excellent: No snags or catching. Good: Few snags. Slightly defective: Has a rough or tangled surface. Defective: Many snags.

[0117] (Surface roughness) The surface of the foamed wire was measured using a laser microscope (VK-X1000) manufactured by Keyence Corporation. The obtained image data was corrected using quadratic surface correction for the wire's range, and then the surface roughness at 500 × 2000 μm was calculated.

[0118] (Number of sparks) 10 4 The number of sparks per meter was measured using a Beta LaserMike Sparktester HFS1220 at a voltage of 1500V.

[0119] (Content of fluorinated low molecular weight compounds) The sample was pulverized by freeze-milling, and the resulting powder was dispersed in methanol and extracted using sonication at 60°C for 2 hours. The extract was quantified using liquid chromatography-mass spectrometry (LC-MS / MS) and the resulting value was defined as the content.

[0120] (Dielectric constant, dielectric loss tangent) The target additive concentration was measured using the empty tube resonator method at a frequency of 6 GHz for premixed pellets (resin composition before foam molding).

[0121] (State of tetrapyrrole cyclic compound (B) at molding temperature) Using a polarizing microscope equipped with a hot stage, we observed whether the tetrapyrrole cyclic compound (B) remained in a solid state when heated to a predetermined temperature.

[0122] Example 1 In step 1, pellets were prepared by adding 1 part by mass of copper phthalocyanine (manufactured by Tokyo Chemical Industry Co., Ltd., no peak detected below a melting point of 350°C, thermal decomposition temperature: 388°C) to 100 parts by mass of FEP pellets. In step 2, foamed wire molding was performed at an extrusion speed (screw rotation speed) of 15 rpm, a nitrogen gas flow rate of 16 cc / min, and a take-up speed of 100 m / min to obtain a foamed wire with an outer diameter of 0.80 mm and a capacitance of 86 pF / m. No smoke or eye discharge was observed during molding, and the number of sparks was 5 out of 10. 4The results were very good. Analysis of the obtained foamed wire showed that the foaming rate was 43%, the bubble size was 21 μm, which was good, the surface texture was extremely good, and the surface roughness was also very good at 6.8 μm. Furthermore, at the molding temperature during foam molding, copper phthalocyanine did not decompose, was insoluble in FEP, and did not melt. Furthermore, no fluorine-based low-molecular-weight compounds were detected in the pellets used or in the coating layer of the prepared foamed wires. Fluorine-based low-molecular-weight compounds were also not detected in the comparative examples described later. Furthermore, SEM images used to calculate the bubble size confirmed the formation of closed bubbles. Closed bubbles were also formed in the subsequent Comparative Examples 1, 3, and 4.

[0123] Comparative Example 1 Foamed wires were prepared using the same method as in Example 1, except that boron nitride (MGP manufactured by Denka Co., Ltd.) was used as an additive. No smoke or eye discharge was observed during molding, but the wire surface condition was poor, with over 300 sparks per 10 units. 4 The results were very poor. Analysis of the obtained foamed wire revealed that the bubble size was large at 36 μm, and the surface roughness was also very poor at 12.4 μm.

[0124] Comparative Example 2 We attempted to produce foamed wire using the same method as in Example 1, except that we used Irgaclear XT386 (a polypropylene transparent nucleating agent manufactured by BASF) as an additive. However, smoke and eye discharge occurred frequently, and we were unable to obtain the desired foamed wire.

[0125] Comparative Example 3 Foamed wires were prepared in the same manner as in Example 1, except that 0.5 parts by mass of potassium titanate (Tismo D, manufactured by Otsuka Chemical Co., Ltd.) was used as an additive. No smoke or eye discharge was observed during molding, but the wire surface condition was slightly poor, with over 100 sparks per 100 units. 4The result was very poor. Analysis of the obtained foamed wire showed that the bubble size was good at 27 μm, but the surface roughness was poor at 10.1 μm.

[0126] Comparative Example 4 Foamed wires were manufactured using the same method as in Example 1, except that no additives were used. No smoke or eye discharge was observed during molding, and the number of sparks was 0 / 10. 4 Although the m value was good, analysis of the resulting foamed wire revealed that the bubble size was very large at 103 μm.

[0127] Comparative Example 5 Foamed wires were prepared in the same manner as in Example 1, except that 0.01 parts by mass of sodium fluorobutanesulfonate (fluorine-based surfactant) and 0.4 parts by mass of boron nitride were used as additives. No smoke or eye discharge was observed during molding, but the wire surface condition was poor, with over 100 sparks per 100 units. 4 The result was poor. Analysis of the obtained foamed wire showed that the bubble size was good at 30 μm, but the surface roughness was very poor at 12.3 μm.

[0128] [Table 4]

Claims

1. A resin composition for foam molding comprising a fluororesin (A) and a tetrapyrrole-based cyclic compound (B).

2. The foam molding resin composition according to claim 1, wherein the fluororesin (A) is a fluororesin that can be melt-molded.

3. The foam molding resin composition according to claim 1 or 2, wherein the fluororesin (A) is at least one selected from the group consisting of tetrafluoroethylene / hexafluoropropylene copolymers and tetrafluoroethylene / perfluoro(alkyl vinyl ether) copolymers.

4. The foam molding resin composition according to claim 1 or 2, wherein the fluororesin (A) is a tetrafluoroethylene / hexafluoropropylene copolymer.

5. The resin composition for foam molding according to claim 1 or 2, wherein the fluororesin (A) is fluorinated.

6. The foam molding resin composition according to claim 1 or 2, wherein the content of the fluororesin (A) is 80 to 99.99% by mass.

7. The foam molding resin composition according to claim 1 or 2, wherein the content of the fluororesin (A) is 97% by mass or more and less than 99.85% by mass.

8. A resin composition for foam molding according to claim 1 or 2, which is substantially free of fluorine-based low molecular weight compounds.

9. The tetrapyrrole cyclic compound (B) is a phthalocyanine skeleton in the foam molding resin composition according to claim 1 or 2.

10. The foam molding resin composition according to claim 1 or 2, wherein the tetrapyrrole cyclic compound (B) is a metal phthalocyanine.

11. The foam molding resin composition according to claim 1 or 2, wherein the tetrapyrrole cyclic compound (B) is copper phthalocyanine.

12. The foam molding resin composition according to claim 1 or 2, wherein the content of the tetrapyrrole cyclic compound (B) is 0.1 to 20 parts by mass per 100 parts by mass of the fluororesin (A).

13. The foam molding resin composition according to claim 1 or 2, wherein the content of the tetrapyrrole cyclic compound (B) is 0.5 to 2.0 parts by mass per 100 parts by mass of the fluororesin (A).

14. A foamed molded article formed using the foaming resin composition according to claim 1 or 2.

15. A method for producing a foamed molded article, comprising the step of foaming and molding the foamed resin composition according to claim 1 or 2.

16. A foamed electric wire having a conductor and a foamed insulating layer formed on the conductor using the foamed molding resin composition described in claim 1 or 2.

17. A method for manufacturing a foamed electric wire, comprising the step of forming a foamed insulating layer on a conductor using the foamed molding resin composition according to claim 1 or 2.

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