In-vehicle network cable

Abstract

To provide a foam molded body and a foamed electric wire which are suitably usable as an electric wire for an on-vehicle network cable.SOLUTION: A composition for foam molding contains a fluororesin (A) and a compound (B) having a thermal decomposition temperature of 300°C or higher and a solubility parameter (SP value) of 8 to 15, and is used for coating an electric wire for an on-vehicle network cable.SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure relates to a composition for foam molding, a foam molded body, a foamed electric wire, a method for manufacturing a foam molded body, a method for manufacturing an electric wire, and an in-vehicle network cable.

Background Art

[0002] Communication networks are widespread in offices, homes, etc. In recent years, with the increase in communication data volume accompanying the adoption of automatic driving support systems, etc., there is a demand for improved communication speed in vehicles, and the introduction of network cables capable of high-speed communication such as Ethernet (registered trademark) is underway.

[0003] Patent Document 1 describes a shielded twisted pair cable having a twisted pair wire formed by twisting a pair of core wires with an insulating coating around a signal conductor and a drain wire, a conductor foil covering the outer periphery of the twisted pair wire, and an outer skin insulating layer covering the outer periphery of the conductor foil, wherein the twisted pair wire is formed by twisting at least two or more drain wires.

[0004] Patent Document 2 discloses an electric wire for an in-vehicle network cable coated with a fluororesin. Patent Document 3 discloses a composition for foam molding and a foamed electric wire using a fluororesin.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0006] An object of the present disclosure is to provide a foam molded body and a foam wire that can be suitably used as an in-vehicle network cable wire.

Means for Solving the Problems

[0007] The present disclosure is A twisted pair cable including a pair of mutually twisted electric wires, and at least one of the pair of electric wires is comprising a core wire, a fluororesin (A) coated on the core wire, and a coating material obtained from a foam molding composition containing a compound (B) having a thermal decomposition temperature of 300 °C or higher and a solubility parameter (SP value) of 8 to 15. The coating material is a foam wire for an in-vehicle network cable, characterized in that the foaming ratio is 20% or more. relating to an in-vehicle network cable characterized by 。

[0008] The compound (B) is preferably a compound containing at least one partial structure selected from the group consisting of an aromatic ring, a phosphate ester group, and an amide group. The compound (B) is preferably a compound containing one or more C6-14 aromatic rings or a salt thereof. The compound (B) is preferably at least one compound selected from the group consisting of phosphate esters and their salts, phosphate ester complex compounds, and compounds having two or more amide groups. The salt of the compound (B) is preferably an alkali metal or an alkaline earth metal.

[0009] The compound (B) is preferably at least one of the compounds represented by the following formulas (1), (2), (3), and (4).

Chemical formula

Chemical formula

Chemical formula

Chemical formula

[0010] For R1, R2, R 21 , R 22 , R 31 and R 33 in Formula (1), Formula (2), and Formula (3), it is preferable that they are alkyl groups having 1 to 8 carbon atoms. For X in Formula (1), Formula (2), and Formula (3), it is preferable that it is at least one of sodium, potassium, rubidium, calcium, and barium.

[0011] The above compound (B) is preferably an aromatic cyclic phosphate salt represented by the above formula (1). The above compound (B) is preferably sodium 2,2'-methylenebis(4,6-di-t-butylphenyl) phosphate.

[0012] The above fluororesin (A) is preferably a fluororesin capable of melt processing. The above fluororesin (A) is preferably at least one selected from the group consisting of tetrafluoroethylene / hexafluoropropylene copolymers, tetrafluoroethylene / perfluoro(alkyl vinyl ether) copolymers, and tetrafluoroethylene / ethylene copolymers.

[0013] The above fluororesin (A) is preferably a fluororesin that has been fluorinated. the above The foaming composition preferably does not substantially contain a fluorine-based low molecular compound.

[0015] The present disclosure A twisted pair cable including a pair of mutually twisted electric wires, and at least one of the pair of electric wires is has a core wire and a fluororesin layer or a fluororesin composition layer coated on the core wire, and is a foamed electric wire in which the fluororesin layer or the fluororesin composition layer has air bubbles, and in observation of a cross-sectional view perpendicular to the length direction, the average bubble diameter of the air bubbles is 20 to 40 μm, and it is a foamed electric wire for an in-vehicle network cable. an in-vehicle network cable characterized by being It is also.

[0016] The present disclosure A twisted pair cable including a pair of mutually twisted electric wires, and at least one of the pair of electric wires is has a core wire and a fluororesin layer or a fluororesin composition layer coated on the core wire, and is a foamed electric wire in which the fluororesin layer or the fluororesin composition layer has air bubbles. In observation of a cross-sectional view parallel to the length direction, the average aspect ratio of the air bubbles is 1.9 or less, and it is a foamed electric wire for an in-vehicle network cable. an in-vehicle network cable characterized by being It is also.

[0017] The present disclosure A twisted pair cable including a pair of mutually twisted electric wires, and at least one of the pair of electric wires is has a core wire and a fluororesin layer or a fluororesin composition layer coated on the core wire, and is a foamed electric wire in which the fluororesin layer or the fluororesin composition layer has air bubbles. In observation of a cross-sectional view parallel to the length direction, the proportion of air bubbles having an aspect ratio of 3 or more is 13% or less with respect to the total amount of air bubbles measured in the cross-sectional view parallel to the length direction, and it is a foamed electric wire for an in-vehicle network cable. an in-vehicle network cable characterized by being It is also.

[0018] The present disclosure A twisted pair cable including a pair of mutually twisted electric wires, and at least one of the pair of electric wires is It has a core wire and a fluororesin layer or a fluororesin composition layer coated on the core wire, and is a foamed wire in which the fluororesin layer or the fluororesin composition layer has bubbles. In the observation of a cross-sectional view parallel to the length direction, the standard deviation of the aspect ratio of the bubbles is 1.3 or less. A foamed wire for an in-vehicle network cable, characterized in that an in-vehicle network cable characterized by being It is also.

[0022] In the above in-vehicle network cable, in the twisted pair cable, it is preferable that the deformation rate after twisting of the foamed wire is 20% or less.

Embodiments for Carrying Out the Invention

[0023] The present disclosure has been completed by finding that by using a specific compound (B) in a foaming resin having a fluoropolymer as a base resin, good foaming can be obtained, and this can be particularly preferably used in an in-vehicle network cable wire. The compound (B) has a thermal decomposition temperature of 300 °C or higher and a solubility parameter (SP value) of 8 to 15. Many conventional foaming nucleating agents have relatively low thermal decomposition temperatures and melting points. When the molding temperature of the resin is low, there is no problem, but in a molding composition containing a resin having a high melting point, there is a problem that it thermally decomposes or melts during the molding process and does not act efficiently as a foaming nucleating agent. In particular, when a fluororesin, which is a high melting point resin, is used, inconveniences such as coloring, generation of decomposition gas, enlargement of bubble size, deterioration of surface state, and deterioration of electrical properties occur, and it has been difficult to balance the physical properties of the fluororesin and the properties of the foamed molded body. The present disclosure has found that by using the compound (B), the composition containing the fluororesin (A) exhibits good foamability, and further, by exhibiting good properties even when molding is performed at a high temperature, the above-described effects can be obtained. Hereinafter, the present disclosure will be described in detail.

[0024] The fluororesin (A) is not particularly limited as long as it is melt-processable. For example, tetrafluoroethylene (TFE) / hexafluoropropylene (HFP) copolymer, TFE / perfluoro(alkyl vinyl ether) (PAVE) copolymer, 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. can be mentioned.

[0025] Examples of the above PAVE include perfluoro(methyl vinyl ether) [PMVE], perfluoro(ethyl vinyl ether) [PEVE], perfluoro(propyl vinyl ether) [PPVE], etc. Among them, PPVE is preferable. These can be used alone or in combination of two or more.

[0026] The fluororesin may have polymerization units based on other monomers in an amount that does not impair the essential properties of each fluororesin. Examples of the above other monomers can be appropriately selected from, for example, TFE, HFP, ethylene, propylene, perfluoro(alkyl vinyl ether), perfluoroalkyl ethylene, hydrofluoroolefin, fluoroalkyl ethylene, perfluoro(alkyl allyl ether), etc. The perfluoroalkyl group constituting the above other monomers preferably has 1 to 10 carbon atoms.

[0027] Because of its excellent heat resistance, the fluororesin is preferably a TFE / HFP copolymer, a TFE / PAVE copolymer, or a TFE / ethylene copolymer, and more preferably a TFE / HFP copolymer or a TFE / PAVE copolymer. The above fluororesins may be used in combination of two or more. Also, because of its more excellent electrical properties, it is preferably a perfluororesin.

[0028] The TFE / HFP copolymer preferably has a mass ratio of TFE / HFP of 80 to 97 / 3 to 20, more preferably 84 to 92 / 8 to 16. The TFE / HFP copolymer may be a binary copolymer composed of TFE and HFP, or may further be a ternary copolymer composed of a comonomer copolymerizable with TFE and HFP (for example, a TFE / HFP / PAVE copolymer). The TFE / HFP copolymer is preferably a TFE / HFP / PAVE copolymer containing a polymerization unit based on PAVE. The TFE / HFP / PAVE copolymer preferably has a mass ratio of TFE / HFP / PAVE of 70 to 97 / 3 to 20 / 0.1 to 10, more preferably 81 to 92 / 5 to 16 / 0.3 to 5.

[0029] The TFE / PAVE copolymer preferably has a mass ratio of TFE / PAVE of 90 to 99 / 1 to 10, more preferably 92 to 97 / 3 to 8.

[0030] The TFE / ethylene copolymer preferably has a molar ratio of TFE / ethylene of 20 to 80 / 20 to 80, more preferably 40 to 65 / 35 to 60. Further, the TFE / ethylene copolymer may contain other monomer components. That is, the TFE / ethylene copolymer may be a binary copolymer composed of TFE and ethylene, or may further be a ternary copolymer composed of a comonomer copolymerizable with TFE and ethylene (for example, a TFE / ethylene / HFP copolymer). The TFE / ethylene copolymer is preferably a TFE / ethylene / HFP copolymer containing a polymerization unit based on HFP. The TFE / ethylene / HFP copolymer preferably has a molar ratio of TFE / ethylene / HFP of 40 to 65 / 30 to 60 / 0.5 to 20, more preferably 40 to 65 / 30 to 60 / 0.5 to 10.

[0031] The melt flow rate (MFR) of the fluororesin is preferably from 0.1 to 500 g / 10 min. More preferably, it is from 4 to 100 g / 10 min, still more preferably from 10 to 80 g / 10 min. Since it can suppress the generation of sparks and increase the foaming ratio, it is even more preferably from 34 to 50 g / 10 min, and particularly preferably from 35 to 40 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.

[0032] The fluororesin can be synthesized by polymerizing monomer components using ordinary polymerization methods, such as emulsion polymerization, suspension polymerization, solution polymerization, bulk polymerization, gas-phase polymerization and other methods. In the above polymerization reaction, a chain transfer agent such as methanol may be used. The fluororesin may be produced by polymerizing and isolating without using a metal ion-containing reagent.

[0033] The fluororesin may have end groups such as -CF3 and -CF2H at at least one of the polymer main chain and the polymer side chain, and is not particularly limited, but is preferably a fluororesin that has been fluorinated. A non-fluorinated fluororesin may have end groups that are thermally and electrically unstable, 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 above fluorination treatment. The fluororesin preferably has few or no such unstable end groups, and the total number of the above four types of unstable end groups and -CF2H end groups is 6 more preferably 50 or less per 1×10 carbon atoms. If it exceeds 50, there is a risk of molding defects. The above unstable end groups are more preferably 20 or less, and still more preferably 10 or less. In this specification, the number of the above unstable end groups is a value obtained from infrared absorption spectrum measurement. The above unstable end groups and -CF2H end groups may not be present and all may be -CF3 end groups.

[0034] The 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 thereof include fluorine radical sources that generate fluorine radicals under fluorination treatment conditions. Examples of the fluorine radical source include F2 gas, CoF3, AgF2, UF6, OF2, N2F2, CF3OF, and halogen fluorides (e.g., IF5, ClF3). The fluorine radical source such as F2 gas may be of 100% concentration, but from the viewpoint of safety, it is preferably diluted with an inert gas to 5 to 50% by mass, preferably 15 to 30% by mass and used. Examples of the inert gas include nitrogen gas, helium gas, argon gas, etc., and nitrogen gas is preferred from an economic aspect. The conditions of the fluorination treatment are not particularly limited, and the molten fluororesin and the fluorine-containing compound may be brought into contact, but usually, it can be carried out at a temperature below the melting point of the fluororesin, preferably 20 to 220 °C, 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 is preferably one in which an unfluorinated fluororesin is brought into contact with fluorine gas (F2 gas).

[0035] The fluororesin (A) is not particularly limited, but since a foamed molded article having excellent heat resistance and a wide continuous use temperature range can be obtained, it is desirable that the melting point is 200 °C or higher, the molding temperature is 250 °C or higher, and the thermal decomposition temperature is 300 °C or higher. Further, the melting point is more preferably 250 °C or higher and preferably 300 °C or lower. The molding temperature is more preferably 300 °C or higher and preferably 450 °C or lower. The thermal decomposition temperature is more preferably 350 °C or higher and even more preferably 400 °C or higher. The upper limit of 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 the temperature suitable for molding that is generally recommended, and at this temperature, it has fluidity and does not cause resin deterioration such as coloring. The thermal decomposition temperature is the 1% weight loss temperature when heated at 10 °C / min in air by TG (measurement of heating weight change). However, the weight loss due to the volatilization of contained water and crystal water observed from 100 °C to 200 °C is excluded. Having fluidity means that the MFR is 0.0001 or more at this temperature.

[0036] In order to reduce the signal loss of the communication wire, 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 more. Similarly, the dielectric 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 more. The dielectric constant and the dielectric tangent are measured by the coaxial resonator method at a frequency of 6 GHz.

[0037] The content of the fluororesin (A) is preferably 50 parts by mass or more, more preferably 80 parts by mass or more, based on 100 parts by mass of the foaming composition. Even more preferably, it is 90 parts by mass or more, still more preferably 95 parts by mass or more, and particularly preferably 98 parts by mass or more. The upper limit is 99.999 parts by mass or less, and more preferably 99.99 parts by mass or less.

[0038] The compound (B) that acts as a foaming nucleating agent in the present disclosure is a compound having a thermal decomposition temperature of 300 °C or higher and a solubility parameter (SP value) of 8 to 15. In the present disclosure, since a foamed molded body having excellent heat resistance and a wide continuous use temperature range can be obtained, the thermal decomposition temperature of the compound (B) needs to be 300 °C or higher. The thermal decomposition temperature is more preferably 350 °C or higher, and still more preferably 400 °C or higher. The upper limit is preferably 600 °C or lower. The measurement of the thermal decomposition temperature can be performed in the same manner as the above-mentioned fluororesin (A).

[0039] In order to effectively exhibit the effects of the present disclosure, it is desirable that compound (B) is not melted at the molding temperature. For this reason, the melting point of compound (B) is preferably 200°C or higher, more preferably 300°C or higher, still more preferably 350°C or higher, and most preferably 400°C or higher. The melting point of compound (B) is the temperature confirmed by the TGA peak during TG measurement. For example, when no peak can be confirmed below 400°C, it is considered to be 400°C or higher. Whether the compound is melting at the peak temperature is confirmed by using a heating microscope or observation in an electric furnace in combination.

[0040] Further, the above-mentioned compound (B) has a solubility parameter (SP value) of 8 to 15. By the SP value being within the above range, the additive particles can be uniformly dispersed, and uniform and fine foaming can be achieved. Furthermore, the generation of large particles due to re-aggregation of the particles during foam molding can be suppressed, the unevenness on the surface of the wire caused by the large particles can be reduced, and the effect of making the surface smooth can be obtained. The above SP value is preferably 9 or higher, more preferably 10 or higher. Also, it is preferably 14 or lower, more preferably 13 or lower, and still more preferably 12 or lower. The above SP value can be determined by Fedors' formula (Polym. Eng. Sci., 14[2], 147 (1974)).

[0041] The above-mentioned compound (B) is preferably a compound containing at least one partial structure selected from the group consisting of an aromatic ring, a phosphate ester group, and an amide group. For example, when the above-mentioned compound (B) contains an aromatic ring, it is preferably a compound containing one or more C6-14 aromatic rings or a salt thereof.

[0042] When the above-mentioned compound (B) contains an amide group, it is preferably a compound having two or more amide groups. Such compounds are not particularly limited. For example, a compound represented by the following formula (4) is preferred.

[0043] [Chemical formula]

[0044] (In the formula, R 41 , R 42 represents a hydrogen atom, an alkyl group or cycloalkyl group having 1 to 8 carbon atoms, or an aryl group, alkylaryl group or arylalkyl group having 6 to 12 carbon atoms, and Ar 41 represents an aryl group.)

[0045] More specifically, examples include N,N'-dicyclohexyl-2,6-naphthalenedicarboxamide (trade name: Enjester NU-100, Shin Nippon Rika Co., Ltd.).

[0046] When the above compound (B) contains a phosphate ester group, it is preferably at least one compound selected from the group consisting of phosphate esters and their salts, and phosphate ester complex compounds. The phosphate ester compounds that can be used as the above compound (B) are typically phosphate esters, phosphite esters, acidic phosphate esters, acidic phosphite esters, or their salts such as ammonia, amines, melamine, alkali metals or alkaline earth metals, and their specific structures are not particularly limited.

[0047] Specific examples thereof include triphenyl phosphate, trilauryl phosphate, tristearyl phosphate, trioleyl phosphate, xylene diphenyl phosphate, ethyl diphenyl phosphate, isopropyl diphenyl phosphate, n-butyl diphenyl phosphate, 2-ethylhexyl diphenyl phosphate, isodecyl diphenyl phosphate, cetyl diphenyl phosphate, stearyl diphenyl phosphate, oleyl diphenyl phosphate, butyl dicresyl phosphate, octyl dicresyl phosphate, lauryl dicresyl phosphate, dibutyl pyrophosphate, monophenyl acid phosphate, diphenyl acid phosphate, monocresyl acid phosphate, dicresyl acid phosphate, monoxylenyl acid phosphate, 2-acryloyloxyethyl acid phosphate, 2-methacryloyloxyethyl acid phosphate, diphenyl(2-acryloyloxyethyl) phosphate, diphenyl(2-methacryloyloxyethyl) phosphate, trinaphthyl phosphate, trinonylphenyl phosphate, tris(2,6-dimethylphenyl) phosphate, tetraphenyl resorcinol diphosphate, tetraphenyl hydroquinone diphosphate, tetraphenyl bisphenol A diphosphate, tetra(2,6-dimethylphenyl) resorcinol diphosphate, tetra(2,6-dimethylphenyl) bisphenol A diphosphate, tetra(2,6-dimethylphenyl) biphenyl diphosphate, tetraphenyl ethylene glycol diphosphate, bis(2,Acidic phosphate esters such as 6-dimethylphenyl)pentaerythritol diphosphate, dixylenyl acid phosphate, or acidic phosphite esters, dimethyl phosphate ammonium salt, diethyl phosphate ammonium salt, ethyl phosphate ammonium salt, di-n-butyl phosphate ammonium salt, dibutoxyethyl phosphate triethanolamine salt, dioctyl phosphate morpholine salt, mono-n-butyl phosphate sodium salt, diphenyl phosphate ammonium salt, diphenyl phosphate melamine salt, diphenyl phosphate piperazine salt, phenyl phosphate ammonium salt, dicresyl phosphate ethylenediamine salt, cresyl phosphate sodium salt, dixylenyl phosphate melamine salt, etc., or acidic phosphite esters, salts of ammonia, amine, melamine, alkali metal or alkaline earth metal, etc. can be mentioned.,

[0048] More specifically, for example, salts of phosphate esters such as sodium bis(4-t-butylphenyl) phosphate, sodium 2,2'-methylenebis(4,6-di-t-butylphenyl) phosphate, (2-hydroxy-2-oxo-4,6,10,12-tetra-t-butyl-1,3,2-dibenzo[d,g]perhydrodioxaphosphorocin sodium salt, bisphenol phosphate diester barium salt, binaphthyl phosphate diester sodium salt, sodium bis(4-nitrophenyl) phosphate, etc. can be mentioned. Also, the ester may be a monoester, diester, triester or more esters. These may be used alone or in combination of two or more kinds.,

[0049] Among them, aromatic phosphate esters are preferred, salts of aromatic phosphate esters are more preferred, and salts of aromatic phosphate esters having a cyclic structure are even more preferred. More preferably, it is a salt of a cyclic phosphate ester having a biphenyl structure, a binaphthyl structure, or a benzohydryl structure, provided that these benzene rings and naphthalene rings may have an alkyl group or a cycloalkyl group having 1 to 8 carbon atoms, or an aryl group, an alkylaryl group, or an arylalkyl group having 6 to 12 carbon atoms. As the aromatic phosphate ester salt having the above cyclic structure, it is preferably at least one of the aromatic cyclic phosphate ester salts represented by the following formulas (1), (2), and (3).

[0050]

Chemical formula

Chemical formula

Chemical formula

[0051] In the formulas, R1, R2, R3, R 4、 R 21 , R 22 , R 23 , R 24 , R 31 , R 32 , R 33 , R 34 represent a hydrogen atom, an alkyl group or a cycloalkyl group having 1 to 8 carbon atoms, or an aryl group, an alkylaryl group, or an arylalkyl group having 6 to 12 carbon atoms, and R 5 , R 6 represent a hydrogen atom or a methyl group, n represents an integer of 1 or 2, m represents an integer of 0 to 2, and X represents a metal of m + n valency.

[0052] R1, R2, R3, R 4、 R 21 , R 22 , R 23 , R 24 , R 31 , R32 and R 33 and R 34 Examples of the alkyl group represented by R include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, amyl, isoamyl, sec-amyl, tert-amyl, hexyl, isohexyl, heptyl, octyl, isooctyl, 2-ethylhexyl, and tert-octyl. Examples of the cycloalkyl group include cyclopentyl, cyclohexyl, and cycloheptyl. Among them, an alkyl group having 1 to 4 carbon atoms and a t-butyl group are preferable.

[0053] R1, R2, R3, R 4、 R 21 and R 22 and R 23 and R 24 and R 31 and R 32 and R 33 and R 34 Examples of the aryl group represented by R include phenyl, naphthyl, and biphenyl. Examples of the alkylaryl group include 4-methylphenyl, 4-tert-butylphenyl, and nonylphenyl. Examples of the arylalkyl group include benzyl, phenethyl, and cumyl.

[0054] Examples of the metal represented by X include alkali metals such as lithium, sodium, potassium, and rubidium, alkaline earth metals such as magnesium, calcium, and barium, aluminum, zinc, titanium, and the like. Among them, at least one of sodium, potassium, rubidium, calcium, and barium is preferable, and sodium or barium is more preferable.

[0055] Among them, compound (B) is preferably an aromatic cyclic phosphate ester salt represented by the above formula (1), and more specifically, it is most preferably sodium 2,2'-methylenebis(4,6-di-t-butylphenyl) phosphate represented by the following formula (5).

[0056]

Chemical formula

[0057] The phosphate complex compound that can be used as the above compound (B) is a complex composed of a metal and an organic compound having a phosphate ester, and its specific structure is not particularly limited. Examples of the organic compound constituting this complex compound include bis(4,4’,6,6’-tetra-t-butyl-2,2’-methylenediphenyl phosphate, 2,2’-methylene-bis(4,6-di-t-butylphenyl) phosphate, 2,2’-methylene-bis(4,6-dimethylphenyl) phosphate, 2,2’-methylene-bis(4,6-dimethylphenyl) phosphate, 2,2’-methylene-bis(4,6-diethylphenyl) phosphate, 2,2’-methylene-bis(4-methyl-6-t-butylphenyl) phosphate, 2,2’-methylene-bis(4-ethyl-6-t-butylphenyl) phosphate, 2,2’-ethylidene-bis(4,6-di-t-butylphenyl) phosphate, 2,2’-ethylidene-bis(4-i-propyl-6-t-butylphenyl) phosphate, 2,2’-ethylidene-bis(4-m-butyl-6-t-butylphenyl) phosphate, 2,2’-butylidene-bis(4,6-dimethylphenyl) phosphate, 2,2’-butylidene-bis(4,6-di-t-butylphenyl) phosphate, 2,2’-t-octylmethylene-bis(4,6-dimethylphenyl) phosphate, 2,2’-t-octylmethylene-bis(4,6-di-t-butylphenyl) phosphate, bis[2,2’-thiobis(4-ethyl-6-t-butylphenyl) phosphate], bis[2,2’-thiobis-(4,6-di-t-butylphenyl) phosphate], bis[2,2’-thiobis-(4-t-octylphenyl) phosphate], bis[2,2’-methylene-bis(4,6-di-t-butylphenyl) phosphate], bis[2,2’-ethylidene-bis(4,6-di-t-butylphenyl) phosphate], bis[(4,4’-dimethyl-6,6’-di-t-butyl-2,2’-biphenyl) phosphate], (4,4’-dimethyl-5,6’-di-t-butyl-2,2’-biphenyl) phosphate, tris[2,2’-methylene-bis(4,6-di-t-butylphenyl) phosphate], tris[2,2’-ethylidene-bis(4,6-di-t-butylphenyl phosphate, phenyl bisdodecyl phosphate, phenyl ethyl hydrogen phosphate, phenyl bis(3,5,5-trimethylhexyl) phosphate, ethyl diphenyl phosphate, 2-ethylhexyl di(tolyl) phosphate, diphenyl hydrogen phosphate, methylene diphenyl phosphate, bis(2-ethylhexyl) p-tolyl phosphate, tritolyl phosphate, bis(2-ethylhexyl) phenyl phosphate, di(nonyl) phenyl phosphate, phenyl methyl hydrogen phosphate, di(dodecyl) p-tolyl phosphate, p-tolyl bis(2,5,5-trimethylhexyl) phosphate, 2-ethylhexyl diphenyl phosphate, tri(butoxyethyl) phosphate, trioctyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, diethyl chloro phosphate, diphenyl chloro phosphate, diethyl bromo phosphate, diphenyl bromo phosphate, dimethyl chloro phosphate, phenyl chloro phosphate, trimethyl phosphate, triethyl phosphate, tri-n-butyl phosphate, tridecyl phosphate, triphenyl phosphate, isopropyl triphenyl phosphate, isodecyl diphenyl phosphate, methylene diphenyl phosphate, etc. may be mentioned.,

[0058] Moreover, examples of the metal constituting the phosphate complex compound include aluminum, sodium, lithium, calcium, magnesium, and barium. These may be used alone or in combination of two or more. Among these, aromatic phosphates are preferred, cyclic aromatic phosphates are more preferred, and sodium complex compounds of aromatic cyclic phosphates are most preferred.,

[0059] Among the above-mentioned compounds (B), specific examples of the compounds having a melting point of 300 °C or higher include, for example, sodium 2,2'-methylenebis(4,6-di-t-butylphenyl) phosphate, etc.,

[0060] The content of the above compound (B) is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, relative to the above fluororesin (A). Even more preferably, it is 5 parts by mass or less, even more preferably 2 parts by mass or less, and particularly preferably 1.5 parts by mass or less. The content of the above compound (B) is preferably 0.001 parts by mass or more, more preferably 0.01 parts by mass or more, relative to the above fluororesin (A). If the content of compound (B) is too small, it becomes difficult to obtain fine bubbles in the resulting coating material, and if it is too large, there is a risk of generating many sparks.

[0061] The foaming composition of the present disclosure may further contain boron nitride as long as the effects of the present disclosure are not impaired.

[0062] The boron nitride preferably has an average particle diameter of 8.0 μm or more. Conventionally, the average particle diameter of boron nitride has a tendency to be small, and the use of boron nitride with a relatively large average particle diameter has not been specifically studied. By containing boron nitride having an average particle diameter within the above specific range, the foaming composition of the present disclosure can form a foamed electric wire provided with a coating material having a smaller average cell diameter and a larger foaming ratio.

[0063] The boron nitride more preferably has an average particle diameter of 9.0 μm or more, even more preferably 10.0 μm or more, even more preferably 10.5 μm or more, particularly preferably 11.0 μm or more, particularly more preferably 12.0 μm or more, and most preferably 13.0 μm or more. Also, if the average particle diameter of the boron nitride is too large, there is a risk that the average cell diameter will become large and that many sparks will be generated. The average particle diameter of the boron nitride is preferably 25 μm or less, more preferably 20 μm or less. By the average particle diameter of the boron nitride being within the above range, a coating material having fine and uniform bubbles can be formed. The average particle diameter of boron nitride is a value obtained using a laser diffraction / scattering particle size distribution analyzer. When using the wet method, the medium can be appropriately selected. For example, methanol or the like can be used.

[0064] Boron nitride preferably has a particle size distribution represented by (D84 - D16) / D50 of 1.2 or less. D84, D50, and D16 represent the particle diameter (μm) at the point where the cumulative curve reaches 84%, 50%, and 16% respectively, when a cumulative curve is obtained with the total volume of the population of boron nitride powder being 100%. Note that the cumulative of the particle size distribution is performed from the smaller particle size side. The total volume of the above powder population 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, Microtrac MT3300 manufactured by Nikkiso Co., Ltd.). When the particle size distribution of boron nitride is within the above range, a coating material having fine and uniform bubbles can be formed, and the generation of sparks can be further suppressed. 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, and for example, it may be 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, Microtrac MT3300 manufactured by Nikkiso Co., Ltd.). When using the wet method, the medium can be appropriately selected. For example, methanol or the like can be used.

[0065] Boron nitride is preferably pulverized. When boron nitride is pulverized, the generation of sparks can be further suppressed. The above pulverization can be performed by methods and conditions that can make the average particle diameter and particle size distribution of boron nitride within the above ranges. For example, the type and conditions of the pulverizer are appropriately selected. As the above pulverizer, for example, a jet mill, a hammer mill, a ball mill, a pin mill, etc. can be used.

[0066] Boron nitride may be adjusted to an average particle size or a particle size distribution within the above range by classification. Although the composition of the present disclosure is not particularly limited, for example, the content of boron nitride is preferably 0.1 to 10% by mass, more preferably 0.1 to 2.0% by mass, still more preferably 0.1 to 1.5% by mass, and even more preferably 0.1 to 1.0% by mass. If the content of boron nitride is too small, it may be difficult to obtain fine bubbles in the coating material of the obtained foamed wire, and if it is too large, the manufacturing cost may increase.

[0067] The foaming composition of the present disclosure may further contain a polyatomic anion-containing inorganic salt within a range not impairing the effects of the present disclosure. Examples of the polyatomic anion-containing inorganic salt include those disclosed in U.S. Patent No. 4,764,538.

[0068] The foaming composition of the present disclosure may further contain a sulfonic acid, a phosphonic acid, or a salt thereof, zeolite, etc. within a range not impairing the effects of the present disclosure. Further, an organic foaming nucleating agent such as ADCA (azodicarbonamide), DPT (N,N'-dinitropentamethylenetetramine), OBSH (4,4'-oxybisbenzenesulfonylhydrazide) may be used in combination.

[0069] The foaming composition of the present disclosure may contain a conventionally known filler within a range not impairing the effects of the present disclosure, in addition to the fluororesin (A) and the compound (B).

[0070] Examples of the above-mentioned filler 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, sericite, diatomaceous earth, silicon nitride, fine silica, fumed silica, alumina, zirconia, quartz powder, kaolin, bentonite, titanium oxide, etc. The shape of the above-mentioned filler is not particularly limited, and examples thereof include fibrous, acicular, columnar, whisker-like, flat plate-like, layered, scaly, balloon-like, porous, chopped fiber-like, powdery, granular, bead-like, etc. Note that the above-mentioned filler is different from boron nitride.

[0071] The foaming composition of the present disclosure may further contain a thermoplastic resin other than the above fluororesin. Examples of the thermoplastic resin other than the above fluororesin include general-purpose resins such as polyethylene resin, polypropylene resin, vinyl chloride resin, polystyrene resin; nylons, polycarbonates, polyether ether ketone resins, polyphenylene sulfide resins, polyaryl ether ketones (PAEK), polyether ketone ketones (PEKK), polyether ketones (PEK), polyether ether ketone ketones (PEEKK), etc.), polyether sulfones (PES), liquid crystal polymers (LCP), polysulfones (PSF), amorphous polyarylate (PAR), polyether nitrile (PEN), thermoplastic polyimide (TPI), polyimide (PI), polyether imide (PEI), polyamide imide (PAI), and other engineering plastics.

[0072] The foaming composition of the present disclosure may further contain other components such as additives. Examples of other components include fillers such as glass fiber, glass powder, asbestos fiber, cellulose fiber, carbon fiber, reinforcing agents, stabilizers, lubricants, pigments, flame retardants, and other additives. The composition for foam molding of the present disclosure can also be obtained by a production method (hereinafter referred to as "the production method of the composition") including, for example, a mixing step of mixing a fluororesin (A), a compound (B), and boron nitride, a filler, an additive, etc. added as necessary to obtain a mixture.

[0073] As the above mixing method, for example, a conventionally known method or the like can be used, but a mixing method in which the above compound (B) is less likely to aggregate is preferable. Examples of the above mixing method include a method using a Henschel mixer, a ribbon mixer, a V blender, a ball mill, etc. Further, for example, a method of mixing by melt kneading can also be mentioned.

[0074] The production method of the composition for foam molding of the present disclosure may include a kneading step of kneading the mixture obtained by the above mixing step. By the above kneading, pellets can be obtained. The above kneading can be carried out, for example, by a method using a conventionally known melt kneader such as a single-screw extruder or a twin-screw extruder.

[0075] The production method of the composition for foam molding may include a step of fluorinating the fluororesin. As the fluorination treatment, the above-described method can be used. The fluorination treatment can be carried out, for example, by bringing the pellets obtained by the above kneading into contact with the above-described fluorine-containing compound.

[0076] Each component such as a thermoplastic resin other than the fluororesin, boron nitride, a polyatomic anion-containing inorganic salt, a filler, and other additives, which has already been described as being able to be contained in the composition for foam molding of the present disclosure, can be appropriately added in each step of the production method of the composition for foam molding according to its properties and the like. Further, a fluororesin and boron nitride may be further added.

[0077] The composition for foam molding of the present disclosure can be suitably used as a foamable composition. Further, the composition for foam molding can be suitably used as a composition for wire coating for forming a coating material for wires.

[0078] The foaming composition of the present disclosure exhibits good foamability without using a fluorosurfactant. As conventional fluorosurfactants, fluorine-based low-molecular compounds have been widely used. If a large amount of such fluorine-based low-molecular compounds is contained, there is a problem that the resin in the molten state during molding is plasticized and the number of sparks increases. Since the foaming composition of the present disclosure substantially does not contain such fluorine-based low-molecular compounds, a foamed molded article excellent in surface state can be obtained without causing the above problems.

[0079] The fluorine-based low-molecular compound is not particularly limited, and examples thereof include perfluoroalkyl acids and perfluorosulfonic acids. 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. are mentioned, and more specifically, {F(CF2)6CH2CH2SO3}2Ba is mentioned.

[0080] The content of the fluorine-based low-molecular compound can be analyzed by the following method: The pellets of the foaming composition were pulverized by cryogenic pulverization, the produced powder was dispersed in methanol, and extracted by applying ultrasonic waves at 60 °C for 2 hours. The value quantified by liquid chromatography-mass spectrometry (LC-MS / MS) of the extract was taken as the content.

[0081] The method for producing a foamed molded article of the present disclosure includes a step of foaming the above foaming composition.

[0082] The method for foam molding the above-described composition for foam molding is not particularly limited. For example, a conventionally known method can be used. For example, a gas can be used with the above-described fluororesin (molten resin), and the composition for foam molding of the present disclosure can be introduced into a screw extruder designed for foam molding operations, and methods such as using a continuous gas injection method can be mentioned.

[0083] As the above gas, for example, gases such as chlorodifluoromethane, nitrogen, carbon dioxide, or a mixture of the above gases can be used, and they may be introduced into the molten resin in the extruder as a pressurized gas, or may be generated by mixing a chemical blowing agent into the molten resin. The above gas dissolves in the molten resin in the extruder.

[0084] The gas dissolved in the above molten resin comes out of the melt when the pressure of the melt suddenly drops when it exits the extrusion die. The extrudate extruded from the extruder is then cooled and solidified by a method such as being introduced into water, for example.

[0085] Since the above foam molded body is obtained by foam molding the above composition for foam molding, it has a low dielectric constant, exhibits a stable capacitance, is lightweight, and can obtain a shape with stable dimensions such as wire diameter and thickness as a coating material described later. The total volume of the bubbles in the foam molded body can be appropriately adjusted according to the application, for example, by adjusting the amount of gas inserted in the above extruder or by selecting the type of gas to be dissolved.

[0086] The above foam molded body is obtained as a molded body molded according to the application when extruded from the above extruder. The method of the above molding is not particularly limited as long as it is heat-melting molding, and examples include extrusion foam molding, injection foam molding, mold foam molding, and the like.

[0087] The shape of the above-mentioned foamed molded article is not particularly limited. For example, it can be made into various shapes such as a coating material for a foamed electric wire, a filament shape such as a wire, a sheet shape, a film shape, a rod shape, a pipe shape, etc. The above-mentioned foamed molded article 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, a cushioning material such as a cushion, etc. Further, the above-mentioned foamed molded article can be particularly preferably used as a coating material for a foamed electric wire. The obtained foamed molded article contains a melt-solidified body and air bubbles of the composition for foamed molding of the present disclosure, and it is preferable that the air bubbles are uniformly distributed in the melt-solidified body. The average bubble diameter of the above-mentioned air bubbles is not limited, but for example, it is preferably 60 μm or less. Also, the average bubble diameter is preferably 0.1 μm or more. The foaming ratio of the above-mentioned foamed molded article is not particularly limited, but it is preferably 20% or more. The upper limit of the foaming ratio is not particularly limited, but for example, it is 80%.

[0088] One of the features of the foamed molded article of the present disclosure is that its surface is smoother than that of a conventional foamed molded article containing a fluororesin. Since the surface is smooth, it can be suitably used for a twinax cable or the like. In the present disclosure, the surface of the foamed molded article can be evaluated by scanning it with bare hands and observing the degree of snag (protrusion) transmitted to the hand at that time. Also, as described later, the surface of the electric wire is measured with a laser microscope, and after specifying the range of the electric wire by quadratic surface correction for surface shape correction on the obtained image data and performing the correction, the surface roughness of 500×2000 μm is calculated, whereby it can also be evaluated numerically. The above-mentioned surface roughness is preferably less than 10.0 μm, more preferably less than 7.0 μm, and even more preferably less than 5.0 μm. The lower limit of the surface roughness may be 0.001 μm or more. In a twinax cable or the like, a two-layer structure of foam (inside) / skin (outside) is preferable in that the surface roughness can be controlled to a more preferable value.

[0089] The method for manufacturing an electric wire according to the present disclosure includes a step of coating a core wire with the above-described composition for foam molding to obtain an electric wire. By using the above-described composition for foam molding, a foamed electric wire having a coating material with fine and uniform air bubbles can be formed. The step of obtaining the above-described electric wire preferably involves foam molding the above-described composition for foam molding. The electric wire obtained by the above-described method for manufacturing an electric wire is composed of a coating material formed from the above-described composition for foam molding and a core wire. An electric wire obtained by coating a core wire with the above-described composition for foam molding is also one of the present disclosures.

[0090] Since the above-described coating material is obtained by coating a core wire with the above-described composition for foam molding, it has fine and uniform air bubbles. Further, it has a low dielectric constant, exhibits a stable capacitance, is lightweight, and can obtain a stable shape such as wire diameter and thickness. In addition, the above-described coating material has a smooth surface similar to the above-described foam molded body and exhibits similar physical properties.

[0091] The above-described electric wire can be produced by the same method as the conventional method except for coating the above-described composition for foam molding on the core wire. For example, it can be produced using extrusion foam molding. Preferred extrusion molding conditions can be appropriately selected according to the composition of the composition used and the size of the core wire.

[0092] As a method for coating the above-described composition for foam molding on a core wire, for example, a gas soluble in a molten fluororesin (molten resin) is used, the above-described composition for foam molding of the present disclosure is introduced into a screw extruder designed for foam molding operation, and a method using a continuous gas injection method can be mentioned. As the above-described gas, the same gas as that used in the method for manufacturing a foam molded body can be used.

[0093] The obtained coating material contains a melt-solidified body of the above-described composition for foam molding of the present disclosure and air bubbles, and it is preferable that the air bubbles are uniformly distributed in the melt-solidified body. The average bubble diameter of the above-mentioned bubbles is not limited, but in a cross-sectional observation perpendicular to the length direction, for example, it is preferably 200 μm or less, more preferably 100 μm or less, still more preferably 50 μm or less, even more preferably 40 μm or less, particularly preferably 30 μm or less, and even more preferably 20 μm or less. Also, the average bubble diameter is preferably 0.1 μm or more, more preferably 0.5 μm or more, and still more preferably 1 μm or more. However, to reduce the foaming diameter, it is necessary to add a large amount of additives. If there are too many additives, sparks are likely to occur. Therefore, the average bubble diameter of the wire for in-vehicle network is preferably 20 to 40 μm, particularly preferably 25 to 35 μm. Such a structure of the coating material is obtained due to the combination of the fluororesin (A) and the specific compound (B) in the composition for foam molding of the present disclosure. The above-mentioned average bubble diameter is a value obtained by taking an image of the cross-section of the coating material with a scanning electron microscope (SEM), calculating the diameter of each bubble by image processing, and averaging them.

[0094] The above-mentioned coating material preferably has a foaming ratio of 20% or more. More preferably, it is 25% or more, still more preferably 30% or more. Particularly preferably, it is 40% or more. The upper limit is not particularly limited, for example, it is 90%. The upper limit of the foaming ratio may be 80% or 60%. In the wire for in-vehicle network, considering the collapse during twisting, 40% or more and 60% or less is preferable. The above-mentioned foaming ratio is a value obtained as ((specific gravity of fluororesin - specific gravity of foam) / specific gravity of fluororesin) × 100. The above-mentioned foaming ratio can be appropriately adjusted according to the application, for example, by adjusting the insertion amount of gas in the above-mentioned extruder or by selecting the type of gas to be dissolved.

[0095] The above-mentioned coating material preferably has less than 5 sparks per 3500 m. More preferably, it is less than 3, and still more preferably 1 or less. The above-mentioned number of sparks is a value obtained by measuring with a Beta LaserMike Sparktester HFS1220 at a voltage of 1500V.

[0096] As the material of the core wire, for example, metal conductor materials such as copper and aluminum, carbon, etc. can be used. Also, even if it is a single material, the surface may be plated with silver, tin, etc. The core wire preferably has a diameter of 0.02 to 3 mm. The diameter of the core wire is more preferably 0.04 mm or more, still more preferably 0.05 mm or more, and particularly preferably 0.1 mm or more. The diameter of the core wire is more preferably 2 mm or less. Also, the above core wire may be a single wire or a stranded wire composed of a plurality of core wires. The shape of the core wire is not particularly limited, and examples include a flat shape and a flat wire. The above wire preferably has a coating material thickness of 0.01 to 3.0 mm. The thickness of the coating material is also preferably 2.0 mm or less. Specific examples of the core wire include, for example, AWG (American Wire Gauge)-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, a wire formed by bundling 7 copper wires with a diameter of 51 micrometers and having a total size of a wire with a diameter of 153 micrometers), AWG-30 (solid copper wire with a diameter of 254 micrometers, a wire formed by bundling 7 copper wires with a diameter of 102 micrometers and having a total size of a wire with a diameter 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), AWG-22 (solid copper wire with a diameter of 635 micrometers), etc. may be used.

[0097] The above-mentioned foamed wire is composed of a core wire and a coating material that coats the core wire. The above-mentioned foamed wire can be used as cables for connecting computers and their peripheral devices, cables for high-speed communication of high-capacity video and audio, cables for connecting servers in data centers, for example, LAN cables, USB cables, Lightning cables, Thunderbolt cables, CATV cables, HDMI (registered trademark) cables, QSFP cables, aerospace wires, underground power transmission cables, submarine power cables, high-voltage cables, superconducting cables, wrapping wires, automotive wires, wire harnesses and electrical components, robot and FA wires, OA equipment wires, information equipment wires (such as optical fiber cables, audio cables, etc.), internal wiring for communication base stations, large-current internal wiring (such as inverters, power conditioners, battery systems, etc.), internal wiring for electronic devices, internal wiring for small electronic devices and mobile devices, 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.

[0098] The above-mentioned wire may have a two-layer structure (skin-foam) with a non-foamed layer inserted between the core wire and the coating material, a two-layer structure (foam-skin) with a non-foamed layer covering the outer layer, or even a three-layer structure (skin-foam-skin) with a non-foamed layer covering the outer layer of the skin-foam. In order to reduce the surface roughness, a foam-skin or skin-foam-skin structure is preferred. The foam-skin structure is preferred because the equipment can be simplified. The total thickness of the skin layer is preferably 200 μm or less, more preferably 100 μm or less, particularly preferably 70 μm or less, and most preferably 40 μm or less. Also, it is preferably 1 μm or more. The non-foamed layer of the above-mentioned wire is not particularly limited and may be a resin layer made of a TFE / HFP copolymer, a TFE / PAVE copolymer, a TFE / ethylene copolymer, a vinylidene fluoride polymer, a polyolefin resin such as polyethylene [PE], a resin such as polyvinyl chloride [PVC], etc.

[0099] Since the composition for foam molding of the present disclosure substantially does not contain a fluorine-based low molecular compound, the above-described foam molded article and the electric wire also substantially do not contain a fluorine-based low molecular compound. The content of the fluorine-based low molecular compound in the above-described foam molded article and the electric wire can also be analyzed in the same manner as in the case of the composition for foam molding described above.

[0100] The present disclosure also includes the following foamed electric wires. (1) A foamed electric wire having a core wire and a fluororesin layer or a fluororesin composition layer coated on the core wire, wherein the fluororesin layer or the fluororesin composition layer has air bubbles, and in observation of a cross-sectional plane parallel to the length direction, the average aspect ratio of the air bubbles is 1.9 or less. (2) A foamed electric wire having a core wire and a fluororesin layer or a fluororesin composition layer coated on the core wire, wherein the fluororesin layer or the fluororesin composition layer has air bubbles, and in observation of a cross-sectional plane parallel to the length direction, the proportion of air bubbles having an aspect ratio of 3 or more is 13% or less with respect to the total amount of air bubbles measured in observation of a cross-sectional plane parallel to the length direction. (3) A foamed electric wire having a core wire and a fluororesin layer or a fluororesin composition layer coated on the core wire, wherein the fluororesin layer or the fluororesin composition layer has air bubbles, and in observation of a cross-sectional plane parallel to the length direction, the standard deviation of the aspect ratio of the air bubbles is 1.3 or less. (4) A foamed electric wire having a core wire and a fluororesin layer or a fluororesin composition layer coated on the core wire, wherein the fluororesin layer or the fluororesin composition layer has air bubbles, the foaming ratio is 20% or more, and the surface roughness is less than 5.0 μm. (5) A foamed electric wire having a core wire and a fluororesin layer or a fluororesin composition layer coated on the core wire, wherein the fluororesin layer or the fluororesin composition layer has air bubbles, and in observation of a cross-sectional plane perpendicular to the length direction, the average bubble diameter of the air bubbles is 20 to 40 μm. (6) A foamed electric wire having a core wire and a fluororesin layer or a fluororesin composition layer coated on the core wire, A foamed electric wire in which the fluororesin layer or the fluororesin composition layer has bubbles, characterized in that the structure of the electric wire has a foam (inside) / skin (outside) structure, and is a foamed electric wire for an in-vehicle network cable.

[0101] The fact that the bubbles contained in the fluororesin layer or the fluororesin composition layer satisfy these physical properties indicates that they have fine and uniform bubbles, have a low dielectric constant, and exhibit a stable capacitance. These fluororesin layers and fluororesin composition layers can be formed, for example, by the composition for foam molding of the present disclosure.

[0102] The average aspect ratio of the above bubbles is 1.9 or less. The average aspect ratio is obtained by taking an image of a cross-section parallel to the length direction of the coating material with a scanning electron microscope (SEM), and calculating the ratio of the major axis to the minor axis (major axis / minor axis) from the major axis and minor axis of each bubble obtained by image processing, and then averaging the aspect ratios thus obtained. The average aspect ratio is preferably 1.8 or less, more preferably 1.6 or less. Also, it is preferably 1.0 or more.

[0103] The proportion of bubbles with an aspect ratio of 3 or more is 13% or less with respect to the total amount of bubbles measured in the observation of a cross-section parallel to the length direction. The above proportion is calculated by taking an image of a cross-section parallel to the length direction of the coating material with a scanning electron microscope (SEM), and calculating the ratio of the bubbles with an aspect ratio of 3 or more obtained by calculating the ratio of the major axis to the minor axis (major axis / minor axis) from the major axis and minor axis of each bubble obtained by image processing. The proportion of bubbles with an aspect ratio of 3 or more is preferably 6% or less, more preferably 3% or less. Also, it is preferably 0.01% or more.

[0104] The standard deviation of the aspect ratio of the above-mentioned bubbles is 1.3 or less. The above standard deviation is calculated by taking an image of a cross-section parallel to the length direction of the coating material with a scanning electron microscope (SEM), and calculating the standard deviation of the aspect ratio obtained by calculating the ratio of the major axis to the minor axis (major axis / minor axis) from the major axis and minor axis of each bubble obtained by image processing. The standard deviation of the above aspect ratio is preferably 1.1 or less, more preferably 0.8 or less, and even more preferably 0.6 or less. Also, it is preferably 0.01 or more.

[0105] The above-mentioned foaming ratio is preferably 20% or more. The above-mentioned foaming ratio is a value obtained by calculating as ((specific gravity of fluororesin - specific gravity of fluororesin layer or fluororesin composition layer) / specific gravity of fluororesin) × 100. The above-mentioned foaming ratio is more preferably 25% or more, and even more preferably 30% or more. 40% or more is even more preferable.

[0106] The above surface roughness is less than 5.0 μm. The above surface roughness is a value obtained by measuring the surface of the wire with a Keyence laser microscope, performing correction by specifying the range of the wire with quadratic surface correction for surface shape correction on the obtained image data, and then calculating the surface roughness of 500 × 200 μm. The above surface roughness is most preferably 3.0 μm or less.

[0107] In the observation of the cross-section perpendicular to the length direction, the average bubble diameter of the above-mentioned bubbles is 20 to 40 μm, preferably 25 to 35 μm. The above average bubble diameter is a value obtained by taking an image of the cross-section of the coating material with a scanning electron microscope (SEM), calculating the diameter of each bubble by image processing, and averaging them.

[0108] In the observation of the cross-section perpendicular to the length direction of the above-mentioned foamed wire, it is preferable that the average bubble diameter of the bubbles is 50 μm or less. The above average bubble diameter is more preferably 40 μm or less, and even more preferably 35 μm or less. Also, it is preferably 0.1 μm or more, more preferably 20 μm or more, and even more preferably 25 μm or more.

[0109] Furthermore, it is preferable that 90% or more of the bubbles have an average bubble diameter of 50 μm or less, and more preferably 95% or more. The maximum bubble diameter is preferably 150 μm or less, and more preferably 100 μm or less. Also, the number of bubbles present in the cross-section is preferably 1500 or less per mm 2 per unit area, more preferably 1000 or less per mm 2 per unit area, and even more preferably 800 or less per mm 2 per unit area.

[0110] In the above-mentioned foamed electric wire, the coating thickness of the fluororesin layer or fluororesin composition layer is preferably 0.4 mm or less, more preferably 0.3 mm or less, and even more preferably 0.25 mm or less. The above coating thickness is a value obtained as (outer diameter of wire coating - core wire diameter) / 2.

[0111] In the above-mentioned foamed electric wire, the core wire diameter is preferably 0.5 mm or less, more preferably 0.4 mm or less, and even more preferably 0.3 mm or less.

[0112] The above-mentioned foamed electric wire is not particularly limited in its manufacturing method, but it is preferably manufactured by the manufacturing method of a foamed electric wire using the above-mentioned foaming composition of the present disclosure. That is, by using the foaming composition of the present disclosure, a foamed electric wire having the above-mentioned performance can be obtained, and various excellent performances can thereby be obtained. The manufacturing method of the above-mentioned foamed electric wire of the present disclosure can be carried out by the above-mentioned steps.

[0113] The foaming composition of the present disclosure is used for coating an in-vehicle network cable. The in-vehicle network cable can be suitably used for large commercial vehicles to passenger cars.

[0114] The in-vehicle network cable of the present disclosure includes a twisted pair cable having a pair of mutually twisted electric wires, and at least one of the pair of electric wires is preferably a foamed electric wire for the in-vehicle network cable of the present disclosure. Also, from the viewpoint of maintaining electrical properties, it is preferable that the twist after twisting of the twisted electric wire is small, and the deformation rate is preferably 20% or less.

[0115] The in-vehicle network cable of the present disclosure includes the foamed electric wire for the in-vehicle network cable of the present disclosure described above. The present disclosure also provides for the use of the in-vehicle network cable in an in-vehicle network.

[0116] Examples of the form of the in-vehicle network cable of the present disclosure include coaxial cables, twisted pair cables, two parallel wires, four parallel wires, eight parallel wires, and the like.

[0117] As the coaxial cable, for example, an external conductor layer made of metal (for example, a metal mesh, etc.) is formed around the foamed electric wire for the in-vehicle network cable of the present disclosure described above, and a resin layer (sheath layer) is formed around the external conductor layer. Examples of the cable include those formed. The resin layer (sheath layer) is not particularly limited, but may be a layer made of a fluorine-containing copolymer having a TFE unit such as a TFE / HFP copolymer or a TFE / PAVE copolymer, a resin such as polyvinyl chloride [PVC], polyethylene, or the like. The external conductor layer and the resin layer (sheath layer) can be coated by a conventionally known method.

[0118] The in-vehicle network cable of the present disclosure includes a twisted pair cable having a pair of mutually twisted electric wires, and at least one of the pair of electric wires is preferably the foamed electric wire for the in-vehicle network cable of the present disclosure described above. By using a twisted pair cable, it becomes less susceptible to the influence of noise, and it is particularly suitable as an in-vehicle network cable where a large amount of noise is likely to occur.

[0119] The in-vehicle network cable of the present disclosure may include a pair of twisted pair cables, or may include two or more pairs of twisted pair cables. The number of twisted pair cables is preferably 1 to 4, more preferably 1 or 2, and even more preferably 1.

[0120] The in-vehicle network cable of the present disclosure preferably includes a jacket surrounding the above-mentioned twisted pair cable. Examples of the material of the jacket include fluorine-containing copolymers having TFE units such as TFE / HFP copolymers and TFE / PAVE copolymers, resins such as polyvinyl chloride [PVC] and polyethylene, but are not limited thereto. The thickness of the jacket is not particularly limited and may be appropriately set according to the purpose.

[0121] The in-vehicle network cable of the present disclosure may include an external conductor layer made of metal (for example, a metal mesh, aluminum foil, etc.) around the above-mentioned twisted pair cable. The above-mentioned external conductor layer functions as a shield, and the stability is further improved. However, from the viewpoints of light weight and bendability, it is preferable not to have a shield.

[0122] The in-vehicle network cable of the present disclosure is preferably an in-vehicle Ethernet cable, and more preferably a network cable of 100BASE-T1 or 1000BASE-T1 specifically.

[0123] The present disclosure also provides an in-vehicle network system including an in-vehicle computer and the in-vehicle network cable of the present disclosure connected to the in-vehicle computer. The in-vehicle network system of the present disclosure only needs to include at least one in-vehicle computer, and may include two or more in-vehicle computers. The in-vehicle computer and the in-vehicle network cable of the present disclosure may be directly connected or indirectly connected. For example, the in-vehicle network cable of the present disclosure and the in-vehicle computer may be connected via a hub, router, or the like. The in-vehicle computer is not limited as long as it is a computer mounted on a vehicle, and examples thereof include an in-vehicle electronic control unit (in-vehicle ECU), an in-vehicle telematics control unit (in-vehicle TCU), and the like. The in-vehicle network system of the present disclosure may include a first in-vehicle computer, a second in-vehicle computer, and an in-vehicle network cable of the present disclosure that connects the first in-vehicle computer and the second in-vehicle computer.

Example

[0124] Hereinafter, the present disclosure will be specifically described based on examples. In the following examples, unless otherwise specified, "parts" and "%" represent "parts by mass" and "mass %", respectively.

[0125] Production Example 1 Preparation of Pellet A Pellet A was obtained in the same manner as in Example 1 of JP-A-2017-128119. The composition of the obtained pellet was a TFE / HFP / PPVE copolymer, TFE / HFP / PPVE = 87.8 / 11.2 / 1.0 (mass ratio), melting point: 255 °C, melt flow rate (MFR): 37 g / 10 min, and the total number of unstable end groups and -CF2H end groups was 0 per 1 × 10 6 carbons.

[0126] Production Example 3 Preparation of Pellet B Pellet B was obtained by fluorinating the pellet obtained in the same manner as in Synthesis Example 1 of WO2005-052015. The composition of the obtained pellet was a TFE / PPVE copolymer, TFE / PPVE = 94.9 / 5.1 (mass ratio), melting point: 255 °C, melt flow rate (MFR): 63 g / 10 min, and the total number of unstable end groups and -CF2H end groups was 0 per 1 × 10 6 carbons.

[0127] Examples 1 to 5 and Comparative Examples 1 to 3 The foamed wire forming was carried out by adding additives to the obtained pellets described above, adjusting the composition for foaming by melt kneading to a predetermined addition amount, using an extruder set to the extruder temperature shown in Table 1. A 22 AWG copper wire (OD: 0.64 mm) was used for the core wire, and the extrusion temperature, nitrogen gas introduction flow rate (pressure), extrusion speed, and take-up speed were adjusted so that the outer diameter after coating was 1.4 mm, the wall thickness was 0.38 mm, the skin was 25 μm, and the capacitance was 40 pF / ft (equivalent to a foaming ratio of 48%). The wire extrusion conditions are shown in Table 2. It was carried out continuously for 1 hour, and spark-out was observed for 3500 m at which the forming was stable. Furthermore, the foaming ratio, average aspect ratio, average cell diameter, and surface roughness of the obtained foamed wire were measured by the following methods. In addition, the collapse of the wire during twinning was evaluated. Tables 3 and 4 show the results of evaluating each characteristic of the obtained wire.

[0128]

Table 1

[0129]

Table 2

[0130] The additives in Tables 3 and 4 are as follows. NA11 (crystal nucleating agent ADEKA STAB NA-11 manufactured by ADEKA CORPORATION): 2,2'-methylenebis(4,6-di-t-butylphenyl) sodium phosphate C4SBa salt: (C4F9SO3)2Ba Gelol MD (manufactured by Shin Nippon Rika Co., Ltd.): bis(4-methylbenzylidene) sorbitol

[0131] The various characteristics in this specification were measured by the following methods. (Measurement of the number of unstable end groups) The pellets were rolled by a hydraulic press to produce a film with a thickness of about 0.3 mm, and the film was analyzed by an FT-IR Spectrometer 1760X (manufactured by Perkin-Elmer). Obtain the difference spectrum from the standard sample (a sample that has been sufficiently fluorinated until there are no substantial differences in the spectrum), read the absorbance of each peak, and calculate the number of unstable end groups per 1×10 6 carbons according to the following formula. Number of unstable end groups per 1×10 6 carbons = (I × K) / t (I; absorbance, K; correction factor, t; film thickness (unit: mm)) The correction factor (K) for each unstable end group is as follows. -COF (1884 cm -1 ) ··· 405 -COOH (1813 cm -1 , 1775 cm -1 ) ··· 455 -COOCH3 (1795 cm -1 ) ··· 355 -CONH2 (3438 cm -1 ) ··· 480 -CH2OH (3648 cm -1 ) ··· 2325

[0132] (Measurement of the number of -CF2H end groups) Using a nuclear magnetic resonance apparatus AC300 (manufactured by Bruker-Biospin), set the measurement temperature to (the melting point of the fluororesin + 20) °C and 19 perform 19F-NMR measurement. Determine it from the integral value of the peak derived from the presence of the -CF2H group and the integral value of other peaks.

[0133] (Melting point) The melting point of the fluororesin was determined as the temperature corresponding to the peak when measured at a heating rate of 10 °C / min using an RDC220 (manufactured by Seiko Instruments Inc.).

[0134] (MFR) The MFR of the fluororesin was determined as the value measured at 372 °C and a load of 5 kg using a KAYENESS Melt Indexer Series4000 (manufactured by Yasuda Seiki Co., Ltd.) with a die diameter of 2.1 mm and a length of 8 mm in accordance with ASTM D-1238.

[0135] (Outer diameter) The outer diameter of the wire was measured using LASER MICRO DIAMETER LDM-303H-XY (manufactured by Takikawa Engineering Co., Ltd.).

[0136] (Capacitance) The capacitance was measured using CAPAC300 19C (manufactured by Zumbach).

[0137] (Number of sparks) The number of sparks per 3500 m was measured at a voltage of 1500 V using Beta LaserMike Sparktester HFS1220.

[0138] (Expansion ratio) It was determined as ((specific gravity of fluororesin - specific gravity of foam) / specific gravity of fluororesin) × 100.

[0139] (Average bubble diameter) SEM images of the wire cross-section perpendicular to the length direction were taken, and the diameter of each bubble was calculated by image processing and averaged to obtain the average bubble diameter.

[0140] (Surface roughness) The wire surface was measured with a Keyence laser microscope. After performing correction by specifying the wire range with quadratic surface correction for surface shape correction on the obtained image data, the surface roughness of 500 × 2000 μm was calculated.

[0141] (Average aspect ratio of bubbles) Images of the cross-section parallel to the length direction of the coating material were taken with a scanning electron microscope (SEM). The aspect ratio was measured by calculating the ratio of the major axis to the minor axis (major axis / minor axis) from the major axis and minor axis of each bubble obtained by image processing and averaging the aspect ratios.

[0142] (Wire dent during twinning) Two electric wires were twisted together under the following twisting conditions using an electric wire twisting machine. The ratio of deformation to the initial wire diameter was defined as the deformation rate, and when the deformation rate was 20% or less, it was considered no crushing. Linear velocity: 19 m / min Twisting: 3,000 twists / min Twist length: 8.5 mm Deformation rate: (Deformation from wire diameter / Initial wire diameter) × 100 (%)

[0143]

Table 3

[0144]

Table 4

[0145] The foamed electric wire obtained in the example did not show any crushing during the twin formation and can be suitably used particularly as an electric wire for in-vehicle network cables.

Industrial Applicability

[0146] The composition for foam molding of the present disclosure is particularly suitable as a material for forming a coating material for foamed electric wires.

Claims

1. A vehicle-mounted network cable comprising a twisted pair cable having a pair of mutually twisted electric wires, wherein at least one of the pair of electric wires comprises a core wire, a fluororesin (A) coated on the core wire, and a coating material obtained from a foamable composition containing a compound (B) having a thermal decomposition temperature of 300 °C or higher and a solubility parameter (SP value) of 8 to 15. The coating material is a foamed electric wire for a vehicle-mounted network cable having a foaming ratio of 20% or more.

2. The vehicle-mounted network cable according to claim 1, wherein the compound (B) is a compound containing at least one partial structure selected from the group consisting of an aromatic ring, a phosphate ester group, and an amide group.

3. The vehicle-mounted network cable according to claim 2, wherein the compound (B) is a compound containing one or more C6-14 aromatic rings or a salt thereof.

4. The vehicle-mounted network cable according to claim 2, wherein the compound (B) is at least one compound selected from the group consisting of a phosphate ester and a salt thereof, a phosphate ester complex compound, and a compound having two or more amide groups.

5. The vehicle-mounted network cable according to claim 3 or 4, wherein the salt of the compound (B) is an alkali metal or an alkaline earth metal.

6. The vehicle-mounted network cable according to any one of claims 2 to 4, wherein the compound (B) is at least one of the compounds represented by the following formulas (1), (2), (3), and (4). 【Chemical 1】 [Chemical Formula 2] 【Chemical Formula 3】 【Chemical Formula 4】 (wherein R １ , R ２ , R ３ , R ４、 R ２１ , R ２２ , R ２３ , R ２４ , R ３１ , R ３２ , R ３３ , R ３４ , R 4１ , R ４２ represents a hydrogen atom, an alkyl group or cycloalkyl group having 1 to 8 carbon atoms, or an aryl group, alkylaryl group or arylalkyl group having 6 to 12 carbon atoms, Ar ４１ represents an aryl group, R ５ , R ６ represents a hydrogen atom or a methyl group, n represents an integer of 1 or 2, m represents an integer of 0 to 2, and X represents a metal having a valence of m + n.) 7. The R in Formula (1), Formula (2), and Formula (3) １、 R ２、 R ２１、 R ２２、 R ３１ and R ３３ The in-vehicle network cable according to claim 6, wherein R is an alkyl group having 1 to 8 carbon atoms.

8. In formulas (1), (2), and (3), X is at least one of sodium, potassium, rubidium, calcium, and barium.

9. The vehicle-mounted network cable according to claim 6, wherein the compound (B) is an aromatic cyclic phosphate ester salt represented by the above formula (1).

10. The vehicle-mounted network cable according to claim 9, wherein the compound (B) is sodium 2,2'-methylenebis(4,6-di-t-butylphenyl) phosphate.

11. The vehicle-mounted network cable according to any one of claims 1 to 4, wherein the fluororesin (A) is a melt-processable fluororesin.

12. The fluororesin (A) is at least one selected from the group consisting of a tetrafluoroethylene / hexafluoropropylene copolymer, a tetrafluoroethylene / perfluoro(alkyl vinyl ether) copolymer, and a tetrafluoroethylene / ethylene copolymer, for the in-vehicle network cable according to any one of claims 1 to 4.

13. The fluororesin (A) is a fluororesin that has been fluorinated, for the in-vehicle network cable according to any one of claims 1 to 4.

14. The foaming composition substantially does not contain a fluorine-based low molecular compound, for the in-vehicle network cable according to any one of claims 1 to 4.

15. It includes a twisted pair cable having a pair of mutually twisted electric wires, and at least one of the pair of electric wires has a core wire and a fluororesin layer or a fluororesin composition layer coated on the core wire, wherein the fluororesin layer or the fluororesin composition layer is a foamed electric wire having bubbles, and in an observation of a cross-section perpendicular to the length direction, the average bubble diameter of the bubbles is 20 to 40 μm. The in-vehicle network cable is characterized by being a foamed electric wire for an in-vehicle network cable.

16. It includes a twisted pair cable having a pair of mutually twisted electric wires, and at least one of the pair of electric wires has a core wire and a fluororesin layer or a fluororesin composition layer coated on the core wire, wherein the fluororesin layer or the fluororesin composition layer is a foamed electric wire having bubbles, and in an observation of a cross-section parallel to the length direction, the average aspect ratio of the bubbles is 1.9 or less. The in-vehicle network cable is characterized by being a foamed electric wire for an in-vehicle network cable.

17. It includes a twisted pair cable having a pair of mutually twisted electric wires, and at least one of the pair of electric wires has a core wire and a fluororesin layer or a fluororesin composition layer coated on the core wire, wherein the fluororesin layer or the fluororesin composition layer is a foamed electric wire having bubbles, and in an observation of a cross-section parallel to the length direction, the proportion of bubbles with an aspect ratio of 3 or more is 13% or less with respect to the total amount of bubbles measured in an observation of a cross-section parallel to the length direction. The in-vehicle network cable is characterized by being a foamed electric wire for an in-vehicle network cable.

18. It includes a twisted pair cable having a pair of mutually twisted electric wires, and at least one of the pair of electric wires It has a core wire and a fluororesin layer or a fluororesin composition layer coated on the core wire, wherein the fluororesin layer or the fluororesin composition layer is a foamed electric wire having air bubbles, in an observation of a cross-sectional view parallel to the longitudinal direction, a standard deviation of the aspect ratio of the air bubbles is 1.3 or less, and the foamed electric wire is for an in-vehicle network cable, characterized in that it is an in-vehicle network cable.

19. The in-vehicle network cable according to claim 1 or 2, wherein in a twisted pair cable, a deformation rate after twisting of the foamed electric wire is 20% or less.

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