Resin compositions for foam molding, interlayer insulators, laminates, and foamed wires.

Abstract

To provide: a resin composition for foam molding that demonstrates good foaming; an interlayer insulator; a layered body; and a foamed electric wire.SOLUTION: The present disclosure provides a resin composition for foam molding that contains a melt-moldable fluororesin and that has a maximum biaxial extensional viscosity of 1×105 to 1×107 Pa s.SELECTED DRAWING: None

Description

【Technical Field】 【0001】 The present disclosure relates to a resin composition for foam molding, an interlayer insulator, a laminate, and a foamed wire. 【Background Art】 【0002】 For cables (wires) for high-speed communication, since the frequency is high and the signal attenuation is large, a reduction in the dielectric constant of the coating material is required. 【0003】 As a method for reducing the dielectric constant, it is known to use a foamed fluorine material (see, for example, Patent Documents 1 to 3). 【Prior Art Documents】 【Patent Documents】 【0004】 【Patent Document 1】 Japanese Patent Application Laid-Open No. 2019-112563 【Patent Document 2】 Specification of Chinese Patent Application Publication No. 116144127 【Patent Document 3】 International Publication No. 2006 / 123694 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0005】 An object of the present disclosure is to provide a resin composition for foam molding, an interlayer insulator, a laminate, and a foamed wire having a good foamed state. 【Means for Solving the Problems】 【0006】 The present disclosure (1) includes a fluororesin that can be melt-molded, and the maximum value of the biaxial elongation viscosity is 1×10 5 ~1×10 7 Pa·s, which is a resin composition for foam molding. 【0007】 Disclosure (2) is a foam molding resin composition according to Disclosure (1), wherein the melt flow rate of the fluororesin is 1 to 100 g / 10 min. 【0008】 Disclosure (3) further relates to the foam molding resin composition according to Disclosure (1) or (2), which further comprises another resin different from the fluororesin. 【0009】 Disclosure (4) is a foam molding resin composition according to Disclosure (3), wherein the melt flow rate of the other resin is less than 1 g / 10 min. 【0010】 Disclosure (5) is a foam molding resin composition according to Disclosure (3) or (4), wherein the other resin is polytetrafluoroethylene. 【0011】 Disclosure (6) is a foam molding resin composition according to any one of Disclosures (3) to (5), wherein the content of the other resin is greater than 0.15% by mass and 3% by mass or less. 【0012】 The present disclosure (7) is a foam molding resin composition according to the present disclosure (6), wherein the content of the other resin is 0.2 to 1% by mass. 【0013】 Disclosure (8) is a foam molding resin composition according to any one of Disclosures (1) to (7), wherein the melting point of the fluororesin is 250°C or higher. 【0014】 Disclosure (9) is a foam molding resin composition according to any one of Disclosures (1) to (8), wherein the fluororesin is a tetrafluoroethylene / hexafluoropropylene copolymer. 【0015】 Disclosure (10) is a foam molding resin composition according to any one of Disclosures (1) to (9) wherein the fluororesin contains a -CF3 terminal group. 【0016】 Disclosure (11) is a foam molding resin composition according to any of Disclosures (1) to (10), wherein the fluororesin content is 80 to 99.99% by mass. 【0017】 The present disclosure (12) is a foam molding resin composition according to the present disclosure (11), wherein the fluororesin content is 97% by mass or more and less than 99.85% by mass. 【0018】 Disclosure (13) further relates to a foam molding resin composition according to any one of Disclosures (1) to (12), comprising a foaming nucleating agent. 【0019】 This disclosure (14) is a foam molding resin composition according to this disclosure (13), wherein the foaming nucleating agent is boron nitride and / or sodium 2,2'-methylenebis(4,6-di-t-butylphenyl)phosphate. 【0020】 The present disclosure (15) is a foam molding resin composition according to the present disclosure (13) or (14), wherein the content of the foaming nucleating agent is 0.1 to 10% by mass. 【0021】 This disclosure (16) is a foam molding resin composition according to this disclosure (15), wherein the foaming nucleating agent content is 0.1 to 3% by mass. 【0022】 Disclosure (17) is a foam molding resin composition according to any of Disclosures (1) to (16) that substantially does not contain fluorine-based low molecular weight compounds. 【0023】 Disclosure (18) is an interlayer insulator formed using a foam molding resin composition described in any of Disclosures (1) to (17). 【0024】 The present disclosure (19) is a laminate having a conductor and a foamed layer formed on the conductor using a foamed resin composition described in any of the present disclosures (1) to (17). 【0025】 The present disclosure (20) 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 (17). [Effects of the Invention] 【0026】 According to this disclosure, it is possible to provide a foam molding resin composition, an interlayer insulator, a laminate, and a foamed electric wire that exhibit a good foamed state. [Brief explanation of the drawing] 【0027】 [Figure 1] This is a circuit diagram of the device used in the improved bubble method. [Figure 2] This is a detailed view of the resin installation section. [Modes for carrying out the invention] 【0028】 The following provides a detailed explanation of this disclosure. 【0029】 The foam molding resin composition disclosed herein comprises a melt-mold fluororesin and has a maximum biaxial extensional viscosity of 1 × 10⁻⁶ 5 ~1 × 10 7 It is Pa·s. 【0030】 The foam molding resin composition of this disclosure contains a melt-mold fluororesin, and the maximum value of the biaxial extensional viscosity is within the above range, thereby suppressing the coalescence of air bubbles and resulting in a good foamed state. A good foaming state is one that is advantageous for achieving a low dielectric constant, and for example, a state in which fine bubbles are uniformly dispersed. 【0031】 Fluororesins that can be melt-molded typically have high melting points and low viscosity, making it difficult to measure their extensional viscosity. Therefore, in this disclosure, the biaxial extensional viscosity is measured (calculated) using the improved bubble method described below. 【0032】 The improved bubble method is a novel testing method developed at Yamagata University. It involves blowing gas into molten resin to create bubbles, measuring the cross-sectional area of ​​these bubbles with a high-speed camera, and then calculating the biaxial extensional viscosity using the following formula. 【number】 η BI :Biaxial elongational viscosity (Pa s) r b: Bubble radius (m) V r : r b Time derivative of P in : Bubble internal pressure (Pa) P o : Atmospheric pressure (Pa) Δr: Bubble film thickness (m) ρ: Melting density (kg / m 3 ) t: Time (s) 【0033】 An example of the apparatus used in the improved bubble method is shown in FIGS. 1 and 2. FIG. 1 is a circuit diagram of the apparatus used in the improved bubble method, and FIG. 2 is a detailed view of the resin installation part. As shown in FIGS. 1 and 2, the apparatus 10 includes an electric furnace 1 and a resin installation part 2 provided in the electric furnace 1. After the sample (resin) heated in the electric furnace 1 is melted, nitrogen gas is blown in, and the molten resin is ejected in a bubble shape from the opening 2a at the bottom of the resin installation part 2. A regulator 3, a ball valve 4, and a pressure sensor 5 are provided in the path from the nitrogen gas insertion port to the electric furnace 1. 【0034】 The specific operation procedure of the improved bubble method is as follows. (1) After molding the resin composition into a sheet with a thickness of 1 mm by a heat press at 360 °C, the sheet is gradually cooled to below the crystallization temperature. (2) Cut the sheet into Φ25 mm to obtain a sample. (3) Preheat the electric furnace to a temperature above the measurement temperature. (4) Confirm that the temperature of the resin installation part in the electric furnace has reached a temperature above the measurement temperature, and install the sample in the resin installation part. (5) After the sample is melted and reaches the measurement temperature, expand the sample into a bubble shape (balloon shape) with nitrogen gas. At this time, observe the behavior during expansion with a high-speed camera (VW-600C manufactured by Keyence), and measure the nitrogen gas pressure (P in - P0) with a pressure sensor. (6) Sample only the bubbles and weigh them. (7) Analyze the video of the bubble taken from a high-speed camera from directly beside it, extract the image from the point where the bubble begins to expose from the resin installation area until the image immediately before the expanded bubble bursts, determine the cross-sectional area of ​​the resin exposed from the resin installation area in that image, and determine the equivalent radius of the circle with that cross-sectional area as the bubble radius (r b ) (8) Based on the measurement results, the biaxial extensional viscosity (η) is calculated from the above formula. BI Calculate ). Note that in the above calculation formula, r b Time derivative (V r ) is the bubble radius (r b The rate of change over time () is used as a substitute. The bubble thickness (Δr) is calculated from the sample volume / bubble surface area. The melt density (ρ) is the density of the sample at the measurement temperature. All other values ​​are measured values. 【0035】 The biaxial extensional viscosity calculated by the improved bubble method typically tends to increase as the bubble grows. The foam molding resin composition of this disclosure has a maximum biaxial extensional viscosity of 1 × 10⁻⁶ as measured by the improved bubble method. 5 ~1 × 10 7 The product was completed after finding that a good foaming state is achieved when the viscosity is Pa·s. The maximum value of the biaxial extensional viscosity is preferably 1 × 10⁻⁶. 5 The above is more comfortable 1.5 × 10 5 More preferably 2 × 10 5 More preferably 2.5 × 10 5 Furthermore, 3 × 10 5 More preferably 3.5 × 10 5 More preferably 4 × 10 5 The above is true, and preferably 1 × 10 6 More preferably 9.5 × 10 5 More preferably 9 × 10 5 Further more preferably 8.5 × 10 5 More preferably, 8 × 10 5 Further more preferably 7.5 × 10 5 Further more preferably, 7 × 10 5 Further more 6.5 × 105 Further, 6 × 10 5 The following applies: The minimum value of the biaxial extensional viscosity is not particularly limited; theoretically it is 0, but it may also be 2. 【0036】 Biaxial extensional viscosity increases by broadening the molecular weight distribution of the resin used. One method for broadening the molecular weight distribution is to dimerize the resin. When dimerizing, the biaxial extensional viscosity increases because molecules with different chain lengths become closely intertwined, more specifically, the dispersion state is good and the difference in molecular chain lengths is large. When using a resin with a high molecular weight, good dispersion is particularly preferable, but the biaxial extensional viscosity becomes sufficiently large when the maximum diameter of the dispersed resin is 10 μm or less. Cocoagulation, described later, is an effective method for highly dispersing a resin with a high molecular weight in a composition. Furthermore, crosslinking the resin can also increase its biaxial extensional viscosity. On the other hand, if aggregates are present in the resin, or if other components such as fillers are present in the resin, the biaxial extension viscosity decreases because the resin breaks at the interface during extension. 【0037】 Hereinafter, the melt-mold fluororesin used in the foam molding resin composition of this disclosure will be referred to as fluororesin (A). The fluororesin (A) is not particularly limited as long as it is melt-moldable, and examples 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. 【0038】 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. 【0039】 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. 【0040】 Because of its excellent heat resistance, the fluororesin (A) is preferably at least one selected from the group consisting of TFE / HFP copolymers, TFE / PAVE copolymers, and TFE / ethylene copolymers, and more preferably a TFE / HFP copolymer. Furthermore, because it has superior electrical properties, it is also preferable to use a perfluororesin. 【0041】 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). It is also preferable that the TFE / HFP copolymer is 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. 【0042】 The TFE / PAVE copolymer preferably has a TFE / PAVE ratio of 90-99 / 1-10 by mass, and more preferably 92-97 / 3-8. 【0043】 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. 【0044】 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. 【0045】 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. 【0046】 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. 【0047】 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. Fluorine radical sources such as F2 gas may be at 100% concentration, but it is preferable to mix them with an inert gas and dilute them to 5-50% by mass, preferably 15-30% by mass, for easier handling. 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). 【0048】 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 300°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 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. 【0049】 To minimize signal loss in communication wires, the dielectric constant of the fluororesin (A) is preferably 3.0 or less, more preferably 2.6 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 0.001 or less, and most preferably 0.0004 or less. The lower limit is 0.0001 or higher. The dielectric constant and dielectric loss tangent are measured by the empty cylinder resonator method at a frequency of 6 GHz. 【0050】 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. 【0051】 The foam molding resin composition of this disclosure preferably contains a resin other than fluororesin (A). The resin other than fluororesin (A) is not particularly limited and may be a fluororesin that cannot be melt-molded or a resin other than a fluororesin, but a fluororesin that cannot be melt-molded is preferred because it has a higher biaxial extensional viscosity and a better foam state. Hereinafter, the non-melt-mold fluororesin used in the foam molding resin composition of this disclosure will be referred to as fluororesin (B). 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. 【0052】 Fluororesin (B) is not particularly limited as long as it is a fluororesin that cannot be melt-molded, but examples include polytetrafluoroethylene (PTFE). In addition, FEP, PFA, ETFE, PCTFE, PVDF, etc., as exemplified in fluororesin (A), can also be used. One or more of these can be used. Among these, PTFE is preferred. Furthermore, for FEPs exemplified as fluororesin (A), if the MFR is less than 1 g / 10 min, it should be classified as fluororesin (B), and if the MFR is 1 g / 10 min or more, it should be classified as fluororesin (A). Therefore, for example, an FEP corresponding to fluororesin (A) and an FEP corresponding to fluororesin (B) may be used in combination. 【0053】 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. 【0054】 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. 【0055】 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. 【0056】 Other resins that can be used besides fluororesin (B) include, for example, 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. 【0057】 The content of other resins different from fluororesin (A) is preferably more than 0.15% by mass, and more preferably 0.16% by mass or more. Even more preferably 0.17% by mass or more, even more preferably 0.2% by mass or more, even more preferably 0.25% by mass or more, and even more preferably 0.4% by mass or more. The upper limit is preferably 3% by mass or less, more preferably 2% by mass or less, and even more preferably 1% by mass or less. If the content of other resins is too low, the effect of increasing biaxial extension viscosity may not be sufficiently obtained, and if the content is too high, poor dispersion may occur, making it easier for the coating to break during wire coating molding. 【0058】 It is preferable that the fluororesin (A) and the other resin are mixed by co-coagulation. Co-coagulation can be carried out, for example, by mixing an aqueous dispersion containing fluororesin (A) with an aqueous dispersion containing the other resin and then allowing it to coagulate. In this specification, the process of mixing aqueous polymer dispersions and then allowing them to coagulate is referred to as "co-coagulation." 【0059】 Co-coagulation can be carried out using conventional methods as appropriate. The polymer solids concentration in each aqueous polymer dispersion is not particularly limited and can be set appropriately depending on the type and amount of each polymer used, but it is preferably 1 to 70% by mass, and more preferably 3 to 50% by mass. The aqueous medium constituting each polymer aqueous dispersion may contain water, but may also contain a water-soluble organic solvent such as a water-soluble alcohol, or it may not contain such a water-soluble organic solvent. Furthermore, each polymer aqueous dispersion preferably contains conventionally known surfactants, etc., to improve dispersibility, to the extent that it does not impair the moldability of the resulting resin. 【0060】 The mixing of the polymer aqueous dispersion can be carried out, for example, using a high-speed stirrer. The mixture obtained by mixing two types of aqueous polymer dispersions is preferably adjusted so that the total solid content concentration of the polymer is 5 to 40% by mass. 【0061】 The coagulation method in co-coagulation is not particularly limited; for example, salt coagulation using nitric acid, hydrochloric acid, etc. as a coagulant is one example. Alternatively, methods that do not use a coagulant and instead induce coagulation mechanically, such as by stirring, are also possible. 【0062】 After co-coagulation, it is preferable to separate the resin by suction filtration and repeat washing with water and suction filtration until the pH becomes neutral. Subsequently, the recovered resin (wet powder) is preferably dried. This drying is preferably carried out at a temperature of 100 to 240°C for 2 to 48 hours. During this time, methods to accelerate drying, such as reducing the pressure or flowing dry gas, can be used. 【0063】 The foam molding resin composition of this disclosure may further contain a foaming nucleating agent. This results in a better foamed state. Examples of foaming nucleating agents 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, and condensed phosphate esters. Other examples include sulfonic acids, sulfonates, phosphonic acids, phosphoates, zeolites, ADCA (azodicarbonamide), DPT (N,N'-dinitropentamethylenetetramine), and OBSH (4,4'-oxybisbenzenesulfonyl hydrazide). Among these, boron nitride and sodium 2,2'-methylenebis(4,6-di-t-butylphenyl)phosphate are preferred. One or more of these can be used. 【0064】 Boron nitride is more preferably 9.0 μm or larger in average particle size, even more preferably 10.0 μm or larger, even more preferably 10.5 μm or larger, particularly preferably 11.0 μm or larger, particularly more preferably 12.0 μm or larger, and most preferably 13.0 μm or larger. Furthermore, if the average particle size of boron nitride is too large, there is a risk that the average bubble size will become large and that many sparks will be generated. The average particle size of boron nitride is preferably 25 μm or less, and more preferably 20 μm or less. By having an average particle size of boron nitride within the above range, it is possible to form a coating material with fine, uniform bubbles. The average particle size of boron nitride was determined using a laser diffraction / scattering particle size distribution analyzer. When using the wet method, the medium can be selected appropriately, but methanol, for example, can be used. 【0065】 Boron nitride is preferably given a particle size distribution of 1.2 or less, expressed as (D84-D16) / D50. D84, D50, and D16 represent the particle size (μm) at which the cumulative curve reaches 84%, 50%, and 16% of the total volume of the boron nitride powder collection, respectively, when the cumulative curve is calculated with the total volume of the boron nitride powder collection set to 100%. The cumulative particle size distribution is calculated starting from the smallest particle size. The total volume of the above powder collection is obtained by preparing a sample in which boron nitride powder is dispersed in a medium such as methanol, and using a laser diffraction / scattering particle size distribution analyzer (for example, a Microtrac MT3300 manufactured by Nikkiso Co., Ltd.). By having a particle size distribution of boron nitride within the above range, it is possible to form a coating material with fine, uniform bubbles, and to further suppress the generation of sparks. The above particle size distribution is more preferably 1.1 or less, and even more preferably 1.0 or less. The lower limit of the particle size distribution is not particularly limited, but may be, for example, 0.1. The cumulative curve of the above particle size distribution (volume particle size distribution) is obtained using a laser diffraction / scattering particle size distribution analyzer (for example, the Microtrac MT3300 manufactured by Nikkiso Co., Ltd.). When using the wet method, the medium can be appropriately selected, but methanol, for example, can be used. 【0066】 It is preferable that the boron nitride is pulverized. When the boron nitride is pulverized, the generation of sparks can be further suppressed. The above grinding can be carried out using a method and conditions that allow the average particle size and particle size distribution of boron nitride to fall within the above range. For example, the type and conditions of the grinder can be appropriately selected. Examples of grinders that can be used include jet mills, hammer mills, ball mills, and pin mills. 【0067】 Boron nitride may be adjusted to the above-mentioned average particle size or particle size distribution by classification. 【0068】 Sodium 2,2'-methylenebis(4,6-di-t-butylphenyl) phosphate more preferably has an average particle size of 20.0 μm or less, even more preferably 10.0 μm or less, even more preferably 5.0 μm or less, and most preferably 2.0 μm or less. Furthermore, if the average particle size of 2,2'-methylenebis(4,6-di-t-butylphenyl)sodium phosphate is too small, its effectiveness as a foaming nucleating agent may decrease. The average particle size of 2,2'-methylenebis(4,6-di-t-butylphenyl)sodium phosphate is preferably 0.001 μm or larger, and more preferably 0.01 μm or larger. By having an average particle size of 2,2'-methylenebis(4,6-di-t-butylphenyl)sodium phosphate within the above range, a coating material with fine, uniform bubbles can be formed. The average particle size of 2,2'-methylenebis(4,6-di-t-butylphenyl)sodium phosphate can be measured using the same method as for the average particle size of boron nitride. 【0069】 In the foam molding resin composition of this disclosure, the content of the foaming nucleating agent is not particularly limited, but is preferably 0.1 to 10% by mass, more preferably 0.1 to 3% by mass, even more preferably 0.1 to 1.5% by mass, and even more preferably 0.1 to 1.0% by mass. If the content of the foaming nucleating agent is too low, the effect of adding the foaming nucleating agent may not be sufficiently obtained, and if it is too high, the manufacturing cost may increase. 【0070】 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. 【0071】 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. 【0072】 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. 【0073】 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. 【0074】 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 or less. 【0075】 The fluorinated low molecular weight compound is not particularly limited and includes, for example, perfluoroalkyl acids and perfluorosulfonic acids, and specifically C8F 17 COOH and its salts, C7F 15 COOH and its salts, C6F13 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 Examples include CH2CH2OH, and more specifically, {F(CF2)6CH2CH2SO3}2Ba. 【0076】 The content of fluorinated low molecular weight compounds can be analyzed by the following method: Pellets of a foam molding resin composition are pulverized by freeze-milling, and the resulting powder is dispersed in methanol and extracted by sonication at 60°C for 2 hours. The extract is quantified using liquid chromatography-mass spectrometry (LC-MS / MS) and the resulting value is taken as the content. 【0077】 The melt flow rate (MFR) of the foam molding resin composition of this disclosure is preferably 1 to 100 g / 10 min. More preferably 5 to 70 g / 10 min, even more preferably 10 to 60 g / 10 min, as this suppresses the generation of sparks and increases the foaming rate; 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, under a load of 5 kg and at 372°C. 【0078】 The foam molding resin composition of this disclosure can be obtained, for example, by a manufacturing method that includes a mixing step of mixing a fluororesin (A) with other resins, etc., which may be added as needed, to obtain a mixture. 【0079】 As for the mixing method described above, for example, conventionally known methods can be used, but a mixing method that increases the biaxial extension viscosity is preferred. The above mixing methods include using a Henschel mixer, ribbon mixer, V-blender, ball mill, etc. Another method is mixing by melt kneading, for example. When fluororesin (A) is used in combination with other resins, the above-mentioned co-coagulation is preferred because it can increase the biaxial extension viscosity. 【0080】 The above manufacturing method may include a kneading step in which the mixture obtained in the above mixing step is kneaded. Pellets can be obtained by the above kneading. The above kneading can be carried out, for example, by using a conventionally known melt kneader such as a single-screw extruder or a twin-screw extruder. 【0081】 The above manufacturing method may include a step of fluorinating the fluororesin. The above-described method can be used for the fluorination treatment. The fluorination treatment may be carried out, for example, by contacting the pellets obtained by the above-described kneading with the fluorine-containing compound described above. 【0082】 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. 【0083】 The method for foam molding the above-mentioned foam molding resin composition is not particularly limited, and conventionally known methods can be used, for example, a method in which the foam molding resin composition of the present disclosure is fed into a screw extruder designed for foaming operations and a continuous gas extrusion method is used. 【0084】 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. 【0085】 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. 【0086】 The foamed molded article obtained by foam molding the foamed resin composition of this disclosure has a low dielectric constant, exhibits stable capacitance, is lightweight, and can be obtained in a shape with stable dimensions such as wire diameter and thickness when used as a coating material as described later. The total volume of bubbles in the foamed molded body can be adjusted as appropriate 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. 【0087】 The foaming state of the above foamed molded product is, for example, determined by the bubble density × the MFR of the composition. 2 ((pcs / mm 2 )·(g / 10 minutes) 2 This can be determined by: Bubble density × MFR of the composition 2 A higher value indicates a greater number of uniformly dispersed fine bubbles and a better foaming state. (Bubble density × MFR of the composition) 2 The value is preferably 5550 or higher, more preferably 5650 or higher, even more preferably 5750 or higher, and particularly preferably 5850 or higher. The upper limit is not particularly limited, but is preferably 8000 or lower, more preferably 7800 or lower, even more preferably 7600 or lower, even more preferably 7400 or lower, even more preferably 7200 or lower, and particularly preferably 7000 or lower. 【0088】 The foamed molded article described above is obtained as a molded article formed according to its intended use during extrusion from the extruder described above. 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. 【0089】 The shape of the foamed molded body described above is not particularly limited and can be in various shapes, such as a covering material for foamed electric wires, a filament-shaped material for wires, a sheet-shaped material, a film-shaped material, a rod-shaped material, or a pipe-shaped material. 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 within the molten and solidified body. The average bubble diameter of the bubbles is not limited, but is preferably 60 μm or less, for example. It is also preferable that the average bubble diameter 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%. 【0090】 The interlayer insulator of this disclosure is formed using the above-mentioned foam molding resin composition. Since the interlayer insulator of this disclosure is in a foamed state that is advantageous for reducing dielectric constant, it can be used for, for example, insulating layers for electric wires, insulating layers for semiconductor package substrates, insulating layers for transformers, insulating layers for circuit boards, insulating layers for motors, insulating layers for reactors, insulating layers for transistors, insulating layers for printed circuit boards, insulating layers for semiconductor devices, insulating layers for electronic components, etc., and is particularly suitable for use as an insulating layer (coating layer) for electric wires. 【0091】 The laminate of the present disclosure comprises a conductor and a foamed layer formed on the conductor using the above-mentioned foam molding resin composition. Since the laminate of the present disclosure has a foamed layer in a foamed state advantageous for low dielectric constant, it can be used, for example, in printed circuit boards, substrates for power modules, coils used in power devices such as motors, secondary batteries such as lithium-ion batteries, primary batteries such as lithium batteries, radical batteries, solar cells, fuel cells, lithium-ion capacitors, hybrid capacitors, electric double-layer capacitors, capacitors (aluminum electrolytic capacitors, tantalum electrolytic capacitors, etc.), electrochromic elements, electrochemical switching elements, electrode separators, etc. The laminates of this disclosure can also be used as antenna components, printed circuit boards, aircraft components, automobile components, heat dissipation components, etc. Specifically, they can be used as wire insulation materials (aircraft wires, flat wires, FFCs (Flexible flat cables), etc.), enamel wire insulation materials used in motors of electric vehicles, etc., insulation materials for power generation, electrical insulation tapes, insulating tapes for oil drilling, printed circuit board materials, tape base films for semiconductor manufacturing processes (dicing tapes, pickup tapes, etc.), release films for semiconductor molding, liquid crystal antennas, transmission lines, base films for COF (Chip on film), electrostatic chucks for semiconductor manufacturing processes, electrostatic chucks for display manufacturing processes, mounting heat dissipation substrates for power devices, heat dissipation components for wireless communication devices, transistors, thyristors, rectifiers, transformers, power MOS FETs, CPUs, heat sinks, metal heat sinks, electronic device materials, sealing materials for plasma processing equipment, heat dissipation components in processing units such as sputtering and various dry etching equipment, and electromagnetic shielding. The laminates of this disclosure can be used as electronic circuit board materials such as flexible printed circuit boards and rigid printed circuit boards, as well as protective films and heat dissipation substrates (especially heat dissipation substrates for automobiles). The laminate of this disclosure can be particularly suitable for use as an electric wire. 【0092】 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 described above. Because the foamed electric wire of this disclosure has a foamed insulating layer in a foamed state that is advantageous for reducing dielectric constant, it can suppress signal attenuation compared to conventional electric wires. 【0093】 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. 【0094】 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). 【0095】 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. 【0096】 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. 【0097】 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]. 【0098】 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] 【0099】 The present disclosure will now be further described with reference to examples, but the present disclosure is not limited to these examples. 【0100】 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 【0101】 (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. 【0102】 (Content of fluorinated low molecular weight compounds) The measurement was performed using the method described above. 【0103】 (SSG) Measurements were taken based on the water displacement method in accordance with ASTM D4895-89. 【0104】 (Melting point) The melting point was defined as the temperature corresponding to the peak measured using an RDC220 (manufactured by Seiko Electronics Co., Ltd.) at a heating rate of 10°C / min. 【0105】 (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. 【0106】 (biaxial elongational viscosity) The measurement was performed using the method described above. The preheating temperature of the electric furnace was 350°C, the resin melting time was 3 minutes, and the measurement temperature was 330°C. 【0107】 The examples and comparative examples were prepared using the following methods. 【0108】 (FEP) As a raw material, a dispersion (aqueous dispersion) obtained by emulsion polymerization using ammonium persulfate as a polymerization initiator was used. The composition of the separated fluororesin (FEP) contained tetrafluoroethylene [TFE] units, hexafluoropropylene [HFP] units, and perfluoro(propyl vinyl ether) [CF2=CFOC3F7(PPVE)] units, and its melting point was 260°C. 【0109】 (PTFE) As the raw material, an aqueous PTFE dispersion prepared by the method of Example 1 in International Publication No. 2019 / 168183 was used. The composition of the separated fluoropolymer (PTFE) was a homopolymer of TFE, with an SSG of 2.173, a melting point of 344°C, and a MFR of 0 g / 10 min. 【0110】 Comparative Example 1, Examples 1-4 A water dispersion (20% resin content by mass), which is the raw material for FEP, was diluted three times, and a water dispersion (20% resin content by mass), which is the raw material for PTFE, was mixed in a ratio to match the desired concentration. The resulting dispersion was stirred using a high-speed stirrer (TK Robomix (stirring unit: homodisper), 3000 rpm, manufactured by Tokushu Kika Kogyo Co., Ltd.), and then a small amount of nitric acid was added dropwise to form a slurry. Next, the resin was separated by suction filtration, and washing with water and suction filtration were repeated until the pH became neutral. The recovered resin was dried at a temperature of 150°C for 6 hours. The dried resin was fluorinated at 200°C for 6 hours under conditions of fluorine gas (F2) diluted to 20% with nitrogen. The resulting resin was found to contain -CF3 terminal groups, as it did not contain the unstable terminal groups and -CF2H terminal groups mentioned above. Furthermore, no fluorine-based low-molecular-weight compounds were detected in the obtained resin. The batch foaming performance evaluation described later is calculated as follows: In Example 1, the foam density × composition MFR 2 In Example 2, the values ​​were 6361 and 6361, respectively, and the MFR of the composition was calculated as: bubble density × composition 2 In Example 4, the result was 6958, and the MFR of the composition was calculated as: bubble density × composition 2 With a ratio of 5903, a good foam with uniformly dispersed fine bubbles was obtained, and in Comparative Example 1, the bubble density × MFR of the composition 2 A poor quality foam was obtained with a ratio of 5478, which contained many coalescing bubbles and large, coarse bubbles. 【0111】 Comparative Examples 2-7 The materials (FEP pellets and PTFE powder) were placed in a laboplast mill (Toyo Seiki Seisakusho 3S150 R60) heated to 350°C and kneaded for 10 minutes at 350°C and 60 rpm. The kneaded resin was fluorinated by contacting it with fluorine gas (F2 gas) diluted to 20% with nitrogen gas at 200°C for 6 hours. The resulting resin was found to contain -CF3 end groups, as it did not contain the unstable end groups and -CF2H end groups mentioned above. Furthermore, no fluorine-based low-molecular-weight compounds were detected in the obtained resin. The batch foaming performance evaluation described later is calculated as: Bubble density of Comparative Example 2 × MFR of the composition 2The result is 5283, and the bubble density of Comparative Example 3 × the MFR of the composition. 2 The result is 5150, and the bubble density of Comparative Example 4 × the MFR of the composition. 2 The result is 5210, and the bubble density of Comparative Example 5 × the MFR of the composition. 2 The result was 5512, and all of them were poor quality foams with many coalescing bubbles and the presence of large bubbles. 【0112】 The resins (compositions) of the examples and comparative examples were evaluated by the following method. 【0113】 (Batch foaming evaluation) Using a laboplast mill, the compositions of the examples and comparative examples, along with a foaming agent (boron nitride), were kneaded at 300°C and 60 rpm for 10 minutes. The foaming agent content in the kneaded mixture was 1% by mass. Using a melt indexer, the kneaded material was formed into strands at 300°C and then cut into pellets. The pellets were placed inside capsules made of aluminum foil, and these capsules were then placed in a high-pressure container preheated to 280°C. The high-pressure container was pressurized with gas (nitrogen), and after being left undisturbed for 60 minutes while maintaining a temperature of 280°C and a pressure of 3 MPa, the pressure was rapidly reduced (within 1 second) and the capsule was removed. After confirming that the resin had hardened, I removed it from the capsule. The resin was cut with a razor blade, the cross-section was observed with a SEM, and the number of bubbles per unit area was determined using an image processing device (Mountec Mac-View) to calculate the bubble density (bubbles / mm²). 2 ) When biaxial extension viscosity increases, bubble coalescence is suppressed, the number of uniformly dispersed fine bubbles increases, and the bubble density improves. Bubble density × MFR of composition 2 ((pcs / mm 2 )·(g / 10 minutes) 2 The foaming state was evaluated based on the value of ). A higher value indicates a greater number of uniformly dispersed fine bubbles and a better foaming state. Generally, foaming properties vary depending on the MFR (Metal Flavor Factor), with lower MFRs tending to produce finer bubbles. 2 By applying this, the effects of MFR can be eliminated. 【0114】 (Evaluation of variance) Thin sections of the compositions from the examples and comparative examples were placed on a hot stage, and the dispersibility of PTFE was evaluated by observing them under crossed nicols using a polarizing microscope (Olympus BX51). The observation was performed after heating the sample to 300°C, which is above the melting point of FEP but below the melting point of PTFE, then to 360°C, which is above the melting point of PTFE, and then cooling it down to 300°C, which is below the melting point of PTFE. Cross-nicol observation revealed interference colors depending on the crystalline components, allowing for crystal observation. The interference colors were identified as PTFE crystals. At 300°C, FEP melts while PTFE does not, allowing observation of PTFE crystals to confirm the dispersion state. Furthermore, raising the temperature to 360°C, above the melting point of PTFE, causes the PTFE to disappear. Cooling back down to 300°C causes the PTFE crystals to reappear. Foaming nucleating agents such as boron nitride do not melt or disappear even at 360°C, thus distinguishing them from PTFE. At 300°C, PTFE crystals were observed, and those with a maximum diameter of 10 μm or less were marked with a circle (○), while those with a maximum diameter greater than 10 μm were marked with a cross (×). When the dispersibility of PTFE is good (〇), the biaxial extensional viscosity increases, the coalescence of bubbles during foaming is suppressed, and there are more uniformly dispersed fine bubbles, resulting in a good foaming state. 【0115】 [Table 1] 【0116】 Although the biaxial extensional viscosity was not measured for Comparative Examples 2 and 5, it is presumed to be similar to that of Comparative Example 3 based on the PTFE concentration, mixing method, and batch foaming evaluation results. 【0117】 Furthermore, PTFE tends to aggregate and its dispersibility deteriorates as the amount (concentration) added increases. Since the dispersibility of the solution with PTFE added by co-coagulation is good even at 1% by mass (Example 4), it is presumed that the dispersibility evaluation of Examples 1 and 3, which have lower concentrations, is also good (○). Regarding the batch foaming evaluation, based on the PTFE concentration, mixing method, and biaxial extensional viscosity, it is presumed that Example 3 is as good as Examples 1 and 2. 【0118】 Furthermore, while boron nitride was used as the foaming nucleating agent in the batch foaming evaluation, it is presumed that similar results would be obtained if 2,2'-methylenebis(4,6-di-t-butylphenyl) sodium phosphate were used. [Explanation of symbols] 【0119】 1: Electric furnace 2: Resin installation part 2a: opening 3: Regulator 4: Ball valve 5: Pressure sensor 10: Equipment

Claims

[Claim 1] This invention comprises a fluororesin with a melt flow rate of 1 to 100 g / 10 min, and other resins different from the fluororesin with a melt flow rate of less than 1 g / 10 min, and a maximum biaxial extensional viscosity of 1 × 10⁻¹⁶ ５ ~1 x 10 ７ It is Pa・s, The fluororesin is at least one selected from the group consisting of tetrafluoroethylene / hexafluoropropylene copolymer, tetrafluoroethylene / perfluoro(alkyl vinyl ether) copolymer, and tetrafluoroethylene / ethylene copolymer. The other resin is at least one selected from the group consisting of polytetrafluoroethylene, tetrafluoroethylene / hexafluoropropylene copolymer, tetrafluoroethylene / perfluoro(alkyl vinyl ether) copolymer, ethylene / tetrafluoroethylene copolymer, polychlorotrifluoroethylene, and polyvinylidene fluoride. A resin composition for foam molding, wherein the content of the aforementioned other resin is 0.2 to 3% by mass. [Claim 2] The foam molding resin composition according to claim 1, wherein the other resin is polytetrafluoroethylene. [Claim 3] The foam molding resin composition according to claim 1 or 2, wherein the content of the other resin is 0.2 to 1% by mass. [Claim 4] The foam molding resin composition according to claim 1 or 2, wherein the melting point of the fluororesin is 250°C or higher. [Claim 5] The foam molding resin composition according to claim 1 or 2, wherein the fluororesin is a tetrafluoroethylene / hexafluoropropylene copolymer. [Claim 6] The aforementioned fluororesin is -CF ３ A foam molding resin composition according to claim 1 or 2, comprising terminal groups. [Claim 7] The foam molding resin composition according to claim 1 or 2, wherein the fluororesin content is 80 to 99.99% by mass. [Claim 8] The foam molding resin composition according to claim 7, wherein the fluororesin content is 97% by mass or more and less than 99.85% by mass. [Claim 9] Furthermore, the foam molding resin composition according to claim 1 or 2 further comprises a foaming nucleating agent. [Claim 10] The foam molding resin composition according to claim 9, wherein the foaming nucleating agent is boron nitride and / or sodium 2,2'-methylenebis(4,6-di-t-butylphenyl)phosphate. [Claim 11] The foam molding resin composition according to claim 9, wherein the content of the foaming nucleating agent is 0.1 to 10% by mass. [Claim 12] The foam molding resin composition according to claim 11, wherein the content of the foaming nucleating agent is 0.1 to 3% by mass. [Claim 13] A resin composition for foam molding according to claim 1 or 2, which is substantially free of fluorine-based low molecular weight compounds. [Claim 14] An interlayer insulator formed using the foam molding resin composition according to claim 1 or 2. [Claim 15] A laminate having a conductor and a foamed layer formed on the conductor using the foamed resin composition according to claim 1 or 2. [Claim 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.

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