WO2019187725A1

WO2019187725A1 - Fluororesin material, fluororesin material for high frequency transmission, and covered electric wire for high-frequency transmission

Info

Publication number: WO2019187725A1
Application number: PCT/JP2019/005096
Authority: WO
Inventors: 今村　均; 昌宏近藤
Original assignee: ダイキン工業株式会社
Priority date: 2018-03-26
Filing date: 2019-02-13
Publication date: 2019-10-03

Abstract

Provided is a fluororesin material that contains a melt-processable fluororesin, that has a relative dielectric constant of 2.1 or less at 12 GHz, and that has a dielectric loss tangent of 0.00030 or less.

Description

Fluororesin material, fluororesin material for high-frequency transmission, and coated wire for high-frequency transmission

This disclosure relates to a fluororesin material, a fluororesin material for high-frequency transmission, and a coated electric wire for high-frequency transmission.

The development of communication means using radio waves is remarkable. Higher frequency regions tend to be used as the amount of information used to transmit radio waves increases. For example, microwaves of 3 to 30 GHz are used for high-frequency wireless LANs, satellite communications, mobile phone base stations, and the like.

As a material of a material used for such a communication device using a high frequency, development of a material having stable electrical characteristics such as a low relative dielectric constant (ε _r ) and a low dielectric loss tangent (tan δ) is in progress. For example, Patent Document 1 proposes a tetrafluoroethylene-based resin molding material with excellent high-frequency electrical characteristics that gives a molded product having a relative dielectric constant of 12 or less at 12 GHz and a dielectric loss tangent of 1.90 × 10 ⁻⁴ or less. Has been.

JP 2001-288227 A

However, since the tetrafluoroethylene-based resin molding material proposed in Patent Document 1 is non-melt-processable, it is melt-processed using conventional processing equipment such as an extruder and an injection-molding machine. Can't get.

Therefore, an object of the present disclosure is to provide a fluororesin material that can be manufactured by melt processing and has excellent high-frequency electrical characteristics.

According to the present disclosure, there is provided a fluororesin material containing a melt processable fluororesin, having a relative dielectric constant at 12 GHz of 2.1 or less and a dielectric loss tangent of 0.00030 or less.

In the fluororesin material of the present disclosure, the number of functional groups per 10 ⁶ main chain carbon atoms of the fluororesin is preferably 6 or less.

In the fluororesin material of the present disclosure, the fluororesin is at least one selected from the group consisting of a tetrafluoroethylene / (per) fluoro (alkyl vinyl ether) copolymer and a tetrafluoroethylene / hexafluoropropylene copolymer. A seed copolymer is preferred.

According to the present disclosure, a fluororesin material for high frequency transmission containing the above fluororesin material is also provided.

According to the present disclosure, there is also provided a high-frequency transmission coated electric wire provided with the above-described fluororesin material as the insulating coating layer, wherein the insulating coating layer is a solid insulating coating layer.

According to the present disclosure, it is possible to provide a fluororesin material that can be manufactured by melt processing and has excellent high-frequency electrical characteristics.

Hereinafter, specific embodiments of the present disclosure will be described in detail, but the present disclosure is not limited to the following embodiments.

The fluororesin material of the present disclosure contains a melt processable fluororesin. In the present disclosure, melt processability means that the polymer can be melted and processed using conventional processing equipment such as an extruder and an injection molding machine. Therefore, the melt processable fluororesin usually has a melt flow rate of 0.01 to 500 g / 10 min as measured by the measurement method described later.

As described in Patent Document 1, a melt-processable tetrafluoroethylene / hexafluoropropylene copolymer, a tetrafluoroethylene / (per) fluoro (alkyl vinyl ether) copolymer, and the like are hexafluoropropylene and ( Since per) fluoro (alkyl vinyl ether) is copolymerized, the dipole moment is increased, and a corresponding decrease in electrical characteristics appears remarkably in the microwave region having a high frequency.

However, when a melt-processable fluororesin is irradiated with radiation under an appropriate irradiation condition, a fluororesin material having a specific dielectric constant and a dielectric loss tangent can be obtained. It has been found that when a fluororesin material having a dielectric loss tangent is used, the attenuation rate of a high-frequency signal is greatly reduced as compared with a conventional melt processable fluororesin. The fluororesin material of the present disclosure has been completed based on this finding.

The relative dielectric constant at 12 GHz of the fluororesin material of the present disclosure is 2.1 or less, and the dielectric loss tangent is 0.00030 or less.

The relative dielectric constant of the fluororesin material of the present disclosure is 2.1 or less, preferably 2.10 or less, more preferably 2.08 or less, and the lower limit is not particularly limited, but preferably 1.80. That's it.

The dielectric loss tangent of the fluororesin material of the present disclosure is 0.00030 or less, preferably 0.00020 or less, and the lower limit is not particularly limited, but is preferably 0.00001 or more.

The relative dielectric constant and dielectric loss tangent are values obtained by measuring changes in resonance frequency and electric field strength at a temperature of 20 to 25 ° C. using a network analyzer HP8510C (manufactured by Hewlett Packard) and a cavity resonator. .

The number of functional groups per 10 ⁶ main chain carbon atoms of the fluororesin material contained in the fluororesin material of the present disclosure is preferably 6 or less, and more preferably, because excellent radio frequency electrical characteristics can be obtained. It is 4 or less, more preferably 2 or less, and particularly preferably 0. The number of functional groups of the fluororesin is the number of functional groups of the fluororesin after irradiation when the fluororesin material is produced by irradiating the fluororesin before irradiation with radiation. Moreover, it is preferable that the number of functional groups of the fluororesin before irradiation is also in the above range. Although a functional group may be newly generated by irradiation, even in this case, the number of functional groups generated by irradiation, including the number of functional groups, is further improved by adjusting it within the above-mentioned range of functional groups. High frequency electrical characteristics can be obtained. Moreover, when the number of functional groups of the fluororesin before irradiation is within the above range, it is presumed that when the fluororesin is irradiated with radiation, the reaction of cross-linking of the functional groups is suppressed and high-frequency electrical characteristics are improved. The In addition, when the number of functional groups is within the above range, there is an advantage that molding defects such as foaming hardly occur when the fluororesin is molded.

Infrared spectroscopic analysis can be used for identification of the types of functional groups and measurement of the number of functional groups.

Specifically, the number of functional groups is measured by the following method. First, the fluororesin is melted at 330 to 340 ° C. for 30 minutes and compression molded to produce a film having a thickness of 0.25 to 0.3 mm. This film is analyzed by Fourier transform infrared spectroscopic analysis to obtain an infrared absorption spectrum of the fluororesin, and a difference spectrum from a base spectrum that is completely fluorinated and has no functional group is obtained. From the absorption peak of a specific functional group appearing in this difference spectrum, the number N of functional groups per 1 × 10 ⁶ carbon atoms in the fluororesin is calculated according to the following formula (A).
N = I × K / t (A)
I: Absorbance K: Correction coefficient t: Film thickness (mm)

For reference, Table 1 shows the absorption frequency, molar extinction coefficient, and correction coefficient for the functional groups in the present disclosure. The molar extinction coefficient is determined from FT-IR measurement data of a low molecular weight model compound.

The absorption frequencies of —CH ₂ CF ₂ H, —CH ₂ COF, —CH ₂ COOH, —CH ₂ COOCH ₃ , —CH ₂ CONH ₂ are shown in the table, respectively, —CF ₂ H, —COF, — The absorption frequency of COOH free, —COOH bonded, —COOCH ₃ , and —CONH ₂ is lower by several tens of Kaiser (cm ⁻¹ ).
Thus, for example, the number of functional groups of —COF is the number of functional groups determined from the absorption peak at an absorption frequency of 1883 cm ⁻¹ due to —CF ₂ COF and the absorption peak at an absorption frequency of 1840 cm ⁻¹ due to —CH ₂ COF. It is the total with the obtained number of functional groups.

The functional group is a functional group present at the main chain end or side chain end of the fluororesin, and a functional group present in the main chain or side chain. The number of functional groups may be the total number of —CF═CF ₂ , —CF ₂ H, —COF, —COOH, —COOCH ₃ , —CONH ₂ and CH ₂ OH.

The functional group is introduced into the fluororesin by, for example, a chain transfer agent or a polymerization initiator used when producing the fluororesin. For example, when alcohol is used as a chain transfer agent or a peroxide having a structure of —CH ₂ OH is used as a polymerization initiator, —CH ₂ OH is introduced at the end of the main chain of the fluororesin. Moreover, the said functional group is introduce | transduced into the side chain terminal of a fluororesin by superposing | polymerizing the monomer which has a functional group.

The fluororesin having the number of functional groups within the above range can be obtained by subjecting the fluororesin having such a functional group to fluorination treatment. That is, it is preferable that the fluororesin contained in the fluororesin material of the present disclosure is fluorinated. The fluororesin contained in the fluororesin material of the present disclosure preferably has a —CF ₃ terminal group.

The fluorination treatment can be performed by bringing a fluorine resin not subjected to fluorination treatment and a fluorine-containing compound into contact with each other.

Although it does not specifically limit as said fluorine-containing compound, The fluorine radical source which generate | occur | produces a fluorine radical under fluorination process conditions is mentioned. Examples of the fluorine radical source include F ₂ gas, CoF ₃ , AgF ₂ , UF ₆ , OF ₂ , N ₂ F ₂ , CF ₃ OF, and halogen fluoride (eg, IF ₅ , ClF ₃ ).

The fluorine radical source such as F ₂ gas may have a concentration of 100%, but is preferably mixed with an inert gas and diluted to 5 to 50% by mass from the viewpoint of safety. It is more preferable to use it diluted to ˜30% by mass. Examples of the inert gas include nitrogen gas, helium gas, and argon gas. Nitrogen gas is preferable from the economical viewpoint.

The conditions for the fluorination treatment are not particularly limited, and the molten fluororesin and the fluorine-containing compound may be brought into contact with each other, but usually below the melting point of the fluororesin, preferably 20 to 220 ° C., more preferably Can be carried out at a temperature of 100 to 200 ° C. The fluorination treatment is generally performed for 1 to 30 hours, preferably 5 to 25 hours. The fluorination treatment is preferably performed by bringing a fluororesin that has not been fluorinated into contact with fluorine gas (F ₂ gas).

The above-mentioned fluororesin preferably has a melting point of 190 to 322 ° C. As said melting | fusing point, More preferably, it is 200 degreeC or more, More preferably, it is 220 degreeC or more, Especially preferably, it is 280 degreeC or more, More preferably, it is 315 degreeC or less. The melting point is a temperature corresponding to the maximum value in the heat of fusion curve when the temperature is raised at a rate of 10 ° C./min using a differential scanning calorimeter [DSC].

The fluororesin is not particularly limited as long as it is a melt processable fluororesin, but tetrafluoroethylene units (TFE units) and (per) fluoro (alkyl vinyl ether) units are obtained because further excellent high-frequency electrical characteristics can be obtained. Copolymer (hereinafter referred to as TFE / PAVE copolymer (or PFA)) and a copolymer (hereinafter referred to as TFE unit and hexafluoropropylene unit (HFP unit)). More preferably, at least one copolymer selected from the group consisting of TFE / HFP copolymer (or FEP), and the group consisting of TFE / PAVE copolymer and TFE / HFP / PAVE copolymer. At least one selected from the above is more preferable, and a TFE / PAVE copolymer is particularly preferable. In particular, it is preferable that the fluororesin is a copolymer containing PAVE units because a fluororesin material having excellent high-frequency electrical characteristics and a relatively high breaking strength can be obtained.

The (per) fluoro (alkyl vinyl ether) (PAVE) may be a fluoroalkyl vinyl ether or a perfluoro (alkyl vinyl ether). In the present disclosure, “perfluoro (alkyl vinyl ether)” is an alkyl vinyl ether containing no C—H bond.
As PAVE constituting the PAVE unit, the general formula (1):
CF ₂ = CFO (CF ₂ CFY ¹ O) _p — (CF ₂ CF ₂ CF ₂ O) _q —R ^f (1)
(Wherein Y ¹ represents F or CF ₃ , R ^f represents a perfluoroalkyl group having 1 to 5 carbon atoms, p represents an integer of 0 to 5 and q represents an integer of 0 to 5). And a monomer represented by the general formula (2):
CFX = CXOCF ₂ OR ¹ (2)
Wherein X is the same or different and represents H, F or CF ₃ , and R ¹ represents at least one atom selected from the group consisting of H, Cl, Br and I, which is linear or branched. 1 to 2 fluoroalkyl groups having 1 to 6 carbon atoms, or 1 to 2 atoms selected from the group consisting of H, Cl, Br and I And a cyclic fluoroalkyl group having a good carbon number of 5 or 6). At least one selected from the group consisting of monomers represented by:

Especially, as said PAVE, the monomer represented by General formula (1) is preferable, From the group which consists of perfluoro (methyl vinyl ether), perfluoro (ethyl vinyl ether), and perfluoro (propyl vinyl ether) (PPVE). At least one selected is more preferable, and PPVE is more preferable.

The content of PAVE units in the TFE / PAVE copolymer is preferably 1.0 to 10% by mass, more preferably 2.0% by mass or more, and still more preferably based on all monomer units. Is 3.5% by mass or more, particularly preferably 4.0% by mass or more, most preferably 5.0% by mass or more, more preferably 8.0% by mass or less, and still more preferably 7% by mass. It is 0.0 mass% or less, Especially preferably, it is 6.5 mass% or less, Most preferably, it is 6.0 mass% or less. The amount of the PAVE unit is measured by ¹⁹ F-NMR method. The TFE / PAVE copolymer may be a copolymer composed only of TFE units and PAVE units.

The melting point of the TFE / PAVE copolymer is preferably 280 to 322 ° C., more preferably 290 ° C. or more, and more preferably 315 ° C. or less.

The glass transition temperature (Tg) of the TFE / PAVE copolymer is preferably 70 to 110 ° C, more preferably 80 ° C or higher, and more preferably 100 ° C or lower. The glass transition temperature is a value obtained by measurement by dynamic viscoelasticity measurement.

The TFE / PAVE copolymer is produced by a conventionally known method such as emulsion polymerization or suspension polymerization by appropriately mixing monomers as constituent units and additives such as a polymerization initiator. Can do.

The TFE / HFP copolymer contains TFE units and HFP units. The content of TFE units in the TFE / HFP copolymer is preferably 70% by mass or more, more preferably 85% by mass or more, and preferably 99.8% by mass with respect to all monomer units. % Or less, more preferably 99% by mass or less, and still more preferably 98% by mass or less.

The TFE / HFP copolymer preferably has a mass ratio (TFE / HFP) of TFE units to HFP units of 70 to 99/1 to 30 (mass%). The mass ratio (TFE / HFP) is more preferably 85 to 95/5 to 15 (mass%).

The TFE / HFP copolymer can further contain (per) fluoro (alkyl vinyl ether) (PAVE) units. Examples of the PAVE unit contained in the TFE / HFP copolymer include the same PAVE units as those described above. Since the TFE / PAVE copolymer described above does not contain HFP units, it differs from the TFE / HFP / PAVE copolymer in that respect.

When the TFE / HFP copolymer is a copolymer containing TFE units, HFP units, and PAVE units (hereinafter also referred to as “TFE / HFP / PAVE copolymer”), the mass ratio (TFE / HFP) / PAVE) is preferably 70 to 99.8 / 0.1 to 25 / 0.1 to 25 (mass%). The mass ratio (TFE / HFP / PAVE) is more preferably 75 to 98 / 1.0 to 15 / 1.0 to 10 (mass%). The TFE / HFP / PAVE copolymer preferably contains 1% by mass or more of HFP units and PAVE units in total.

In the TFE / HFP / PAVE copolymer, the HFP unit is preferably 25% by mass or less based on the total monomer units. The content of the HFP unit is more preferably 20% by mass or less, still more preferably 18% by mass or less, and particularly preferably 15% by mass or less. Further, the content of the HFP unit is preferably 0.1% by mass or more, more preferably 1% by mass or more, and particularly preferably 2% by mass or more. The content of the HFP unit can be measured by ¹⁹ F-NMR method.

The content of the PAVE unit is more preferably 20% by mass or less, and further preferably 10% by mass or less. Especially preferably, it is 3 mass% or less. Further, the content of the PAVE unit is preferably 0.1% by mass or more, and more preferably 1% by mass or more. The content of the PAVE unit can be measured by ¹⁹ F-NMR method.

The TFE / HFP copolymer may further contain other ethylenic monomer (α) units. The other ethylenic monomer (α) unit is not particularly limited as long as it is a monomer unit copolymerizable with TFE, HFP and PAVE. For example, vinyl fluoride (VF), vinylidene fluoride (VdF) ), Fluorinated ethylenic monomers such as chlorotrifluoroethylene [CTFE] and ethylene (ETFE), and non-fluorinated ethylenic monomers such as ethylene, propylene and alkyl vinyl ether. The content of other ethylenic monomer (α) units is preferably 0 to 25% by mass, more preferably 0.1 to 25% by mass.

When the copolymer is a TFE / HFP / PAVE / other ethylenic monomer (α) copolymer, the mass ratio (TFE / HFP / PAVE / other ethylenic monomer (α)) is: It is preferably 70 to 98 / 0.1 to 25 / 0.1 to 25 / 0.1 to 25 (mass%). The TFE / HFP / PAVE / other ethylenic monomer (α) copolymer preferably contains 1% by mass or more of monomer units other than TFE units in total.

The melting point of the TFE / HFP copolymer is preferably 200 to 322 ° C., more preferably more than 200 ° C., further preferably 220 ° C. or more, more preferably 300 ° C. or less, and further preferably It is 280 degrees C or less.

The glass transition temperature (Tg) of the TFE / HFP copolymer is preferably 60 to 110 ° C., more preferably 65 ° C. or more, and more preferably 100 ° C. or less. The glass transition temperature is a value obtained by measurement by dynamic viscoelasticity measurement.

The TFE / HFP copolymer is prepared by a conventionally known method such as emulsion polymerization, solution polymerization, suspension polymerization, or the like by appropriately mixing monomers as constituent units and additives such as a polymerization initiator. Can be manufactured.

The fluororesin is preferably the TFE / PAVE copolymer and the TFE / HFP copolymer. That is, the TFE / PAVE copolymer and the TFE / HFP copolymer can be mixed and used. The mass ratio ((A) / (B)) between the TFE / PAVE copolymer and the TFE / HFP copolymer is preferably 1/9 to 7/3, more preferably 5/5 to 2 / 8.

The above mixture is a mixture of two or more of the above fluororesins and melt-mixed (melt-kneaded), mixed with a resin dispersion after emulsion polymerization, and coagulated with an acid such as nitric acid to recover the resin, etc. It may be prepared by a known method.

The melt flow rate (MFR) of the fluororesin at 372 ° C. is preferably 0.1 to 100 g / 10 minutes, more preferably 0.5 g / 10 minutes or more, more preferably 80 g / 10 minutes or less. Yes, more preferably 40 g / 10 min or less. When the MFR is within the above range, further excellent high-frequency electrical characteristics can be obtained, and even better melt processability can be obtained. According to ASTM D1238, the MFR uses a melt indexer (manufactured by Yasuda Seiki Seisakusho Co., Ltd.), and the mass of the polymer flowing out per 10 minutes from a nozzle having an inner diameter of 2 mm and a length of 8 mm under a load of 372 ° C. and 5 kg (g / 10) Min)).

The breaking strength of the fluororesin material of the present disclosure is preferably 13 MPa or more, more preferably 15 MPa or more, and the upper limit is not particularly limited, but may be 30 MPa or less, or 25 MPa or less. The fluororesin material of the present disclosure can be manufactured by melt processing and at the same time has such a high breaking strength. When the breaking strength of the fluororesin material of the present disclosure is within the above range, the breaking strength of the fluororesin material of the present disclosure can be applied to applications that require high mechanical strength.

The fluororesin material of the present disclosure may contain other components as necessary. Other components include additives such as crosslinking agents, antistatic agents, heat stabilizers, foaming agents, foaming nucleating agents, antioxidants, surfactants, photopolymerization initiators, antiwear agents, surface modifiers, etc. Can be mentioned.

The fluororesin material of the present disclosure can be manufactured, for example, by a manufacturing method including a step of irradiating 20 to 100 kGy of radiation at 80 to 240 ° C. with respect to an unirradiated fluororesin.

The irradiation temperature of the radiation is 80 to 240 ° C., preferably 100 ° C. or more, more preferably 140 ° C. or more, and preferably 220 ° C. from the viewpoint of achieving both excellent high-frequency electrical characteristics and high breaking strength. It is below, More preferably, it is 200 degrees C or less, More preferably, it is 180 degrees C or less. The irradiation temperature is preferably within the above numerical range and lower than the melting point of the fluororesin before irradiation with radiation.

The adjustment of the irradiation temperature is not particularly limited, and can be performed by a known method. Specifically, a method of holding the above-mentioned fluororesin in a heating furnace maintained at a predetermined temperature, placing on a hot plate, energizing a heater built in the hot plate, or hot plate by an external heating means The method of heating is mentioned.

The radiation dose is 20 to 100 kGy, preferably 95 kGy or less, more preferably 80 kGy or less, preferably 30 kGy or more, from the viewpoint of achieving both excellent high-frequency electrical characteristics and high breaking strength. More preferably, it is 40 kGy or more.

Examples of radiation include electron beams, ultraviolet rays, gamma rays, X-rays, neutron rays, high energy ions, and the like. Among these, an electron beam is preferable because it has excellent transmission power, a high dose rate, and is suitable for industrial production.

The method of irradiating radiation is not particularly limited, and examples thereof include a method performed using a conventionally known radiation irradiating apparatus.

The irradiation environment is not particularly limited, but the oxygen concentration is preferably 1000 ppm or less, more preferably in the absence of oxygen, and in an inert gas atmosphere such as nitrogen, helium or argon More preferably, it is in the middle.

The above-described method for producing a fluororesin material preferably further includes a step of molding a non-irradiated fluororesin or a step of molding a fluororesin after irradiation. In addition, since the molding is easy, it is preferable to mold the fluororesin before irradiating with radiation. That is, it is more preferable that the above method for producing a fluororesin material further includes a step of molding a fluororesin that has not been irradiated with radiation. The above fluororesin material manufacturing method includes these steps, whereby a fluororesin material having a desired shape can be manufactured.

As a method for molding the fluororesin, a method can be used in which the fluororesin is heated to a melting point or higher and melted. The method for molding the fluororesin is not particularly limited, and examples thereof include known methods such as extrusion molding, injection molding, transfer molding, inflation molding, and compression molding. What is necessary is just to select these shaping | molding methods suitably according to the shape of the fluororesin material obtained.

The shape of the fluororesin material of the present disclosure is not particularly limited, and examples thereof include pellets, films, sheets, plates, rods, blocks, cylinders, containers, electric wires, and tubes. Also, coating layers for cooking utensils such as rice cookers, hot plates and frying pans, and topcoat layers for fixing rollers for image forming devices such as electrophotographic or electrostatic recording copying machines and laser printers are formed. A fluororesin coating film may be used. The fluororesin coating film can be formed by applying a fluororesin paint to a substrate.

Since the fluororesin material of the present disclosure has a low relative dielectric constant and dielectric loss tangent, it can be particularly suitably used as a fluororesin material for high-frequency transmission.

The dielectric loss α of the high frequency signal can be calculated by the following equation.

In the above equation, k is a constant, ε _r is a relative dielectric constant, tan δ is a dielectric loss tangent, f is a signal frequency, and A is a dielectric loss contribution. By using the fluororesin material of the present disclosure, the dielectric loss contribution A of the dielectric loss α of the high-frequency signal can be reduced, so that it is possible to realize a high-frequency transmission product with extremely low high-frequency transmission loss.

The product for high-frequency signal transmission is not particularly limited as long as it is a product used for high-frequency signal transmission. (1) Insulation plates for high-frequency circuits, insulators for connection parts, molded boards such as printed wiring boards, (2) Examples include bases for high-frequency vacuum tubes, molded articles such as antenna covers, and (3) covered electric wires such as coaxial cables and LAN cables.

In the above high-frequency signal transmission product, the fluororesin material of the present disclosure can be suitably used as an insulator because it has a low relative dielectric constant and dielectric loss tangent.

The above (1) molded board is preferably a printed wiring board in that good electrical characteristics can be obtained. Although it does not specifically limit as said printed wiring board, For example, the printed wiring board of electronic circuits, such as a mobile telephone, various computers, and communication apparatuses, is mentioned. As said (2) molded article, an antenna cover is preferable at a point with low dielectric loss.

Although it does not specifically limit as said (1) shaping | molding board and (2) The manufacturing method for manufacturing a molded article, For example, in the process of shape | molding the radiation-irradiated fluororesin, and the shape | molded fluororesin, said process The manufacturing method including the process of irradiating radiation on irradiation conditions is mentioned. Examples of the molding method in this case include compression molding and extrusion rolling molding.

As the above-mentioned (3) coated electric wire, a high-frequency transmission coated electric wire provided with the fluororesin material of the present disclosure is preferable as an insulating coating layer in that good electrical characteristics can be obtained. When the high-frequency transmission coated electric wire is provided with an insulating coating layer formed of the fluororesin material, extremely small high-frequency transmission loss can be obtained. The high frequency transmission covered electric wire may be a high frequency transmission cable, and a coaxial cable is preferable as the high frequency transmission cable. The coaxial cable generally has a structure in which an inner conductor, an insulating coating layer, an outer conductor layer, and a protective coating layer are sequentially laminated from the core portion to the outer peripheral portion. The thickness of each layer in the above structure is not particularly limited, but usually the inner conductor has a diameter of about 0.1 to 3 mm, the insulating coating layer has a thickness of about 0.3 to 3 mm, and the outer conductor layer has a thickness of about The protective coating layer has a thickness of about 0.5 to 2 mm.

The above-mentioned insulating coating layer may be a foamed insulating coating layer. However, the coated electric wire for high-frequency transmission has the low relative dielectric constant and dielectric loss tangent of the fluororesin material of the present disclosure, and a low transmission loss can be obtained without foaming. The insulating coating layer formed from the material may be a solid insulating coating layer. When the coated wire for high-frequency transmission is formed of the fluororesin material and has a solid insulating coating layer without voids, the mechanical strength of the coated wire for high-frequency transmission is excellent, Even if the coated wire for high-frequency transmission is bent, the stability of the relative dielectric constant is not easily lost. In the present disclosure, the term “solid” means that the inside is filled with a fluororesin material and there is substantially no void. In addition, a void formed unintentionally due to a molding defect or the like may be included. On the other hand, many voids exist in the foamed insulation coating layer. From the above, the fluororesin material of the present disclosure may be a solid fluororesin material.

The above-mentioned (3) covered electric wire includes, for example, a step of coating a non-radiated fluororesin on the inner conductor by extrusion molding to form a covering layer on the inner conductor, and the irradiation on the covering layer. It can be manufactured by a manufacturing method including a step of obtaining a covered electric wire including the fluororesin material as an insulating coating layer by irradiating radiation under conditions to form the fluororesin material.

The product for high-frequency signal transmission can be suitably used for devices using microwaves, particularly 3 to 30 MHz microwaves such as satellite communication devices and mobile phone base stations.

Although the embodiments have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the claims.

Next, the embodiment of the present disclosure will be described with reference to examples, but the present disclosure is not limited to such examples.

Each numerical value of the example was measured by the following method.

(Monomer unit content)
The content of each monomer unit was measured by ¹⁹ F-NMR method.

(MFR)
In accordance with ASTM D1238, using a melt indexer (manufactured by Yasuda Seiki Seisakusho Co., Ltd.), the mass (g / 10 minutes) of the polymer flowing out per 10 minutes from a nozzle having an inner diameter of 2 mm and a length of 8 mm under a load of 372 ° C. and 5 kg. Asked.
(Melting point)
It calculated | required as temperature corresponding to the maximum value in the heat of fusion curve when it heated up at the speed | rate of 10 degree-C / min using the differential scanning calorimeter [DSC].

(Number of functional groups)
The sample is melted at 330 to 340 ° C. for 30 minutes and compression molded to produce a film having a thickness of 0.25 to 0.3 mm. This film was scanned 40 times with a Fourier transform infrared spectrometer [FT-IR (trade name: 1760X type, manufactured by PerkinElmer)] and analyzed to obtain an infrared absorption spectrum, which was completely fluorinated and functionalized. To obtain a difference spectrum from the base spectrum in which no exists. From the absorption peak of a specific functional group appearing in this difference spectrum, the number N of functional groups per 1 × 10 ⁶ carbon atoms in the sample is calculated according to the following formula (A).

N = I × K / t (A)
I: Absorbance K: Correction coefficient t: Film thickness (mm)

For reference, Table 2 shows the absorption frequency, molar extinction coefficient, and correction coefficient for the functional groups in the present disclosure. The molar extinction coefficient is determined from FT-IR measurement data of a low molecular weight model compound.

(Breaking strength and strength retention)
From the test piece (compression molding) obtained in the examples or comparative examples, a dumbbell-shaped test piece was cut out using an ASTM V-type dumbbell, and an autograph (AGS manufactured by Shimadzu Corporation) was used using the obtained dumbbell-shaped test piece. -J 5 kN), the breaking strength was measured at 25 ° C. under the conditions of 50 mm / min according to ASTM D638.
The strength retention was determined by the following formula.
Strength retention (%) = (breaking strength after electron beam irradiation / breaking strength as reference) × 100
The reference breaking strength is the breaking strength of the test piece after fluorination treatment and before electron beam irradiation. For Examples 1 to 5, the breaking strength of Comparative Example 2 was used as the reference breaking strength. For Examples 6 to 7, the breaking strength of Comparative Example 4 was used as the breaking strength as a reference. For Example 8, the breaking strength of Comparative Example 6 was used as the reference breaking strength.

(Dielectric loss tangent, relative permittivity, and dielectric loss contribution)
The dielectric loss tangent and relative dielectric constant of the test pieces (extrusion molding) obtained in the examples or comparative examples were measured by the cavity resonator method. Using a network analyzer (HP8510C, manufactured by Hewlett-Packard Company), changes in resonance frequency and Q value (electric field strength) were measured at a temperature of 20 to 25 ° C., and a dielectric loss tangent (tan δ) and a relative dielectric constant (ε _{r at} 12 GHz). ) Was measured. Further, the dielectric loss contribution A was determined from the following equation from the dielectric loss tangent and relative dielectric constant.

Comparative Example 1
TFE / PPVE copolymer pellets were used.
Composition: TFE / PPVE = 94.5 / 5.5 (mass%)
MFR: 26.0 (g / 10 min)
Melting point: 303 ° C
Number of functional groups: 321 (OH / COF / COOH = 150/17/154 (pieces))

(Creation of test piece (extrusion molding))
The pellets were extruded using an extruder. 6 g of the above pellets are put into a cylinder with a diameter of 10 mm, heated and melted at 372 ° C. for 5 minutes, extruded with a 5 kg load from a die with a diameter of 2 mmφ and a length of 8 mm, and formed into a bar shape with a length of 100 mm. A test piece (extrusion molding) was obtained. By the above method, the dielectric loss tangent, relative permittivity, and dielectric loss contribution of the obtained test piece (extrusion molding) were measured. The results are shown in Table 3.

(Creation of test piece (compression molding))
The pellets were molded into a disk shape having a diameter of 120 mm and a thickness of 1.5 mm using a heat press molding machine to obtain a test piece (compression molding). By the above method, the breaking strength and strength retention of the obtained test piece (compression molding) were measured. The results are shown in Table 3.

Comparative Example 2
The pellet used in Comparative Example 1 was put in a container, and fluorine gas diluted to 20 mass% with nitrogen gas was passed at 200 ° C. at normal pressure for 10 hours to perform fluorine gas treatment. When the number of functional groups was measured using pellets obtained by the fluorine gas treatment, no functional groups were detected. Further, a test piece (extrusion molding) and a test piece (compression molding) were obtained and evaluated in the same manner as in Comparative Example 1 except that pellets obtained by the fluorine gas treatment were used. The results are shown in Table 3.

Example 1
The test piece (extrusion molding) and the test piece (compression molding) obtained in Comparative Example 2 are accommodated in an electron beam irradiation container of an electron beam irradiation apparatus (manufactured by NHV Corporation), and then nitrogen gas is added to the container. Was put in a nitrogen atmosphere. After confirming that the temperature in the container was stable at the irradiation temperature described in Table 3, each test piece was listed in Table 3 under the conditions of an electron beam acceleration voltage of 3000 kV and an irradiation dose intensity of 20 kGy / 5 min. Irradiation dose of electron beam was applied. Evaluation was performed in the same manner as in Comparative Example 1 except that a test piece irradiated with an electron beam was used. The results are shown in Table 3.

Examples 2-5
A test piece was obtained in the same manner as in Example 1 except that the electron beam was irradiated under the conditions described in Table 3. Evaluation was performed in the same manner as in Comparative Example 1 using the obtained test piece. The results are shown in Table 3.

Comparative Example 3
A test piece was obtained in the same manner as in Comparative Example 1 except that pellets of TFE / PPVE / HFP copolymer were used. Evaluation was performed in the same manner as in Comparative Example 1 using the obtained test piece. The results are shown in Table 3.
Composition: TFE / PPVE / HFP = 87.9 / 1.0 / 11.1 (mass%)
MFR: 24.0 (g / 10 min)
Melting point: 257 ° C
Number of functional groups: 517 (COF / COOH / CF ₂ H = 22/12/483 (pieces))

Comparative Example 4
Fluorine gas treatment was performed in the same manner as in Comparative Example 2 except that the pellets used in Comparative Example 3 were used. When the number of functional groups was measured using pellets obtained by the fluorine gas treatment, no functional groups were detected. Further, a test piece (extrusion molding) and a test piece (compression molding) were obtained and evaluated in the same manner as in Comparative Example 1 except that pellets obtained by the fluorine gas treatment were used. The results are shown in Table 3.

Examples 6-7
A test piece was obtained in the same manner as in Example 1 except that the pellet obtained in Comparative Example 4 was used and irradiated with an electron beam under the conditions described in Table 3. Evaluation was performed in the same manner as in Comparative Example 1 using the obtained test piece. The results are shown in Table 3.

Comparative Example 5
A test piece was obtained in the same manner as in Comparative Example 1 except that pellets of TFE / HFP copolymer were used. Evaluation was performed in the same manner as in Comparative Example 1 using the obtained test piece. The results are shown in Table 3.
Composition: TFE / HFP = 88.9 / 11.1 (mass%)
MFR: 27.0 (g / 10 min)
Melting point: 266 ° C
Number of functional groups: 404 (COF / COOH / CF ₂ H = 2/28/374 (pieces))

Comparative Example 6
A fluorine gas treatment was performed in the same manner as in Comparative Example 2 except that the pellets used in Comparative Example 5 were used. When the number of functional groups was measured using pellets obtained by the fluorine gas treatment, no functional groups were detected. Further, a test piece (extrusion molding) and a test piece (compression molding) were obtained and evaluated in the same manner as in Comparative Example 1 except that pellets obtained by the fluorine gas treatment were used. The results are shown in Table 3.

Example 8
A test piece was obtained in the same manner as in Example 1 except that the pellet obtained in Comparative Example 6 was used and irradiated with an electron beam under the conditions described in Table 3. Evaluation was performed in the same manner as in Comparative Example 1 using the obtained test piece. The results are shown in Table 3.

Claims

A fluororesin material containing a melt processable fluororesin, having a relative dielectric constant of 2.1 or less at 12 GHz and a dielectric loss tangent of 0.00030 or less.
2. The fluororesin material according to claim 1, wherein the fluororesin has 6 or less functional groups per 10 6 main chain carbon atoms.
The fluororesin is at least one copolymer selected from the group consisting of a tetrafluoroethylene / (per) fluoro (alkyl vinyl ether) copolymer and a tetrafluoroethylene / hexafluoropropylene copolymer. Item 3. The fluororesin material according to Item 1 or 2.
A fluororesin material for high-frequency transmission, comprising the fluororesin material according to any one of claims 1 to 3.
A coated electric wire for high-frequency transmission, comprising the fluororesin material according to any one of claims 1 to 3 as the insulating coating layer, wherein the insulating coating layer is a solid insulating coating layer.