Method for producing polytetrafluoroethylene composition, polytetrafluoroethylene composition, molded article, conductive tube, heat-conducting film, and substrate for CCL

Abstract

The present invention provides a method for producing a polytetrafluoroethylene composition, comprising a step of mixing a polytetrafluoroethylene resin and a filler using an airflow mixer to obtain a polytetrafluoroethylene composition comprising the polytetrafluoroethylene resin and the filler. Also provided are a polytetrafluoroethylene composition produced by the production method, a polytetrafluoroethylene composition having specific physical properties, and a molded article, a conductive tube, a heat-conducting film, and a CCL substrate obtained using the polytetrafluoroethylene composition.

Description

[0001] (This application is a divisional application of patent application No. 201980080627.3, filed December 4, 2019, entitled “Method for producing polytetrafluoroethylene composition, polytetrafluoroethylene composition, molded article, conductive tube, thermally conductive film, and CCL substrate.”) Technical Field

[0002] The present invention relates to a method for producing a polytetrafluoroethylene composition, a polytetrafluoroethylene composition produced by the method, a polytetrafluoroethylene composition having specific physical properties, and a molded article, a conductive tube, a thermally conductive film, and a CCL substrate obtained using the polytetrafluoroethylene composition. Background Art

[0003] Polytetrafluoroethylene (PTFE) is widely used due to its excellent properties such as high and low temperature resistance, corrosion resistance, aging resistance, high insulation, and low viscosity. However, due to its poor dimensional stability, poor thermal conductivity, low hardness, and susceptibility to wear, its application in mechanical load-bearing, friction and wear, and sealing and lubrication is limited.

[0004] In order to expand the application range of polytetrafluoroethylene, people have proposed to improve its performance by blending polytetrafluoroethylene with other fillers. As methods for blending polytetrafluoroethylene with other fillers, dry mixing and wet mixing are known in the prior art. However, in dry mixing (for example, mechanical stirring), since the PTFE dispersed resin is sensitive to shear force and easily becomes fibrous, and the filler is prone to agglomeration, the polytetrafluoroethylene and the filler cannot be mixed evenly, and the coated PTFE particles are incomplete (see the particles after compounding). Figure 1 The wet mixing method requires the use of solvents, which is not environmentally friendly and has a complicated process (see the composite particles). Figure 2 ).

[0005] Patent Document 1 discloses a method of dry-mixing modified polytetrafluoroethylene having an extrusion pressure of less than 25 MPa at RR1600 with a filler in a mechanical stirring device equipped with stirring blades.

[0006] Patent Document 2 discloses a method for obtaining a uniform mixed powder by wet mixing polytetrafluoroethylene and a filler, wherein polytetrafluoroethylene agglomerated powder formed by agglomerating the emulsion-polymerized particles is obtained by coagulation from an aqueous dispersion of polytetrafluoroethylene emulsion-polymerized particles, the agglomerated powder is then mixed with the filler and dry ice, and the mixture is added to an isopropyl alcohol aqueous solution for granulation.

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2018-109149

[0008] Patent Document 2: Japanese Patent Application Laid-Open No. 2015-151543 Summary of the Invention

[0009] The present invention has been made in view of the above-mentioned situation in the prior art, and its object is to provide a method for producing a polytetrafluoroethylene composition that can uniformly mix a polytetrafluoroethylene resin and a filler without easily agglomerating, as well as a polytetrafluoroethylene composition produced by the method for producing a polytetrafluoroethylene composition, a polytetrafluoroethylene composition having specific physical properties, and a molded article, a conductive tube, a thermally conductive film, and a CCL substrate obtained using the polytetrafluoroethylene composition.

[0010] The method for producing the polytetrafluoroethylene composition of the present invention is characterized by comprising the step of mixing the polytetrafluoroethylene resin and the filler using an air flow mixer to obtain the polytetrafluoroethylene composition comprising the polytetrafluoroethylene resin and the filler.

[0011] In the production method of the present invention, an air flow mixer is used to mix the polytetrafluoroethylene resin and filler. Because the mixing process with an air flow mixer lacks mechanical transmission and shear forces, it is particularly suitable for dispersing PTFE resin. The compressed air can also disintegrate lumps or agglomerated materials. Thus, the production method of the present invention can produce a polytetrafluoroethylene composition in which the polytetrafluoroethylene resin and filler are uniformly mixed and not prone to agglomeration.

[0012] In other words, according to the production method of the present invention, polytetrafluoroethylene can be mixed with a filler without excessively fibrillating the polytetrafluoroethylene, and a polytetrafluoroethylene composition in which polytetrafluoroethylene and the filler are uniformly mixed can be obtained.

[0013] In the production method of the present invention, the filler is preferably coated on the surface of the polytetrafluoroethylene resin particles. Because the present invention utilizes an airflow mixer for mixing, the shear-sensitive polytetrafluoroethylene resin is prevented from excessive fiberization, enabling more uniform mixing of the polytetrafluoroethylene resin and the filler, while also allowing the filler to be evenly coated on the surface of the polytetrafluoroethylene resin particles.

[0014] In the manufacturing method of the present invention, the air flow mixer is preferably a pulsed air flow mixer, which can increase the contact probability between the PTFE and the filler during the mixing process, thereby making the mixing more uniform.

[0015] In the manufacturing method of the present invention, the pulse interval of the pulsed airflow mixer is preferably adjusted to 5 to 30 seconds during the mixing step. This increases the contact probability between the PTFE and the filler during the mixing process, thereby achieving more uniform mixing and improving production efficiency.

[0016] In the manufacturing method of the present invention, preferably, during the mixing step, the single pulse airflow time of the pulse airflow mixer is set to 0.8 to 2 seconds. This increases the probability of the PTFE at the bottom of the mixer participating in the mixing, while also allowing the PTFE and filler to be fully mixed.

[0017] In the production method of the present invention, it is preferred that the number of pulses of the pulse-type airflow mixer in the mixing step be set to 5 or more and 40 or less. This allows for more complete and uniform mixing and improves mixing efficiency.

[0018] In the manufacturing method of the present invention, the air inlet pressure of the air flow mixer is preferably adjusted to 0.4 MPa or higher and 0.8 MPa or lower during the mixing step. This increases the mixing space, resulting in more complete and uniform mixing, while also preventing the raw materials from adhering to the top of the mixing chamber and the dust collector due to excessive air pressure.

[0019] In the production method of the present invention, it is preferred that the temperature in the mixing chamber of the air flow mixer be controlled within a range of 5° C. to 30° C. in the mixing step. This can improve the fluidity of the particles and enhance the mixing efficiency.

[0020] In the production method of the present invention, it is preferred that the temperature within the mixing chamber of the airflow mixer be controlled within a range of 5°C to 19°C during the mixing step. The method for controlling the temperature to this level is not particularly limited, but for example, the mixing chamber can be kept at a low temperature by circulating a coolant or using a refrigerated air dryer, thereby achieving a better mixing effect.

[0021] In the manufacturing method of the present invention, the polytetrafluoroethylene resin is preferably a polytetrafluoroethylene dispersion resin. Generally, polytetrafluoroethylene dispersion resins are more susceptible to shear forces, while the manufacturing method of the present invention does not involve shear forces, and is therefore more suitable for mixing polytetrafluoroethylene dispersion resins with fillers.

[0022] In the production method of the present invention, the filler is preferably a functional filler or a color powder, wherein the functional filler is an organic filler or an inorganic filler. The organic filler is one or more selected from aramid fiber, polyphenylene ester, polyphenylene sulfide, polyimide, polyetheretherketone, polyphenylene, polyamide, and wholly aromatic polyester resin. The inorganic filler is one or more selected from metal powder, graphite, carbon black, coke, carbon powder, carbon fiber, graphene, carbon nanotubes, ceramic powder, talc, mica, aluminum oxide, zinc oxide, tin oxide, titanium oxide, silicon dioxide, calcium carbonate, calcium oxide, magnesium oxide, potassium titanate, glass fiber, glass flakes, glass beads, silicon carbide, calcium fluoride, boron nitride, barium sulfate, molybdenum disulfide, and potassium carbonate whiskers. Different types of fillers may also be used in combination. Furthermore, even if fillers are of the same type, fillers of different shapes or sizes may be used in combination.

[0023] In the manufacturing method of the present invention, the amount of filler added in the mixing step is preferably 0.1% by weight to 60% by weight relative to the total amount of the polytetrafluoroethylene resin and the filler. This can further improve the performance of the final molded product.

[0024] In the production method of the present invention, it is preferred that the particle size of the filler in the mixing step is 10 nm to 100 μm, thereby enabling more uniform mixing.

[0025] In the manufacturing method of the present invention, the loading coefficient of the polytetrafluoroethylene resin and filler during the mixing step is preferably 0.2 or higher and 0.6 or lower. This ensures sufficient mixing space, improving the mixing effect, while also ensuring a high spatial density of the PTFE and filler within the mixing chamber, increasing their contact probability and improving mixing efficiency.

[0026] According to the manufacturing method of the present invention, a polytetrafluoroethylene composition in which polytetrafluoroethylene resin and filler are uniformly mixed and not easily agglomerated can be obtained, and the polytetrafluoroethylene composition can be used to obtain conductive tubes, thermal conductive films and CCL substrates with good performance.

[0027] The present invention also relates to a polytetrafluoroethylene composition characterized by comprising polytetrafluoroethylene resin particles and a filler coating the surface of the particles, and being substantially free of organic solvent. The polytetrafluoroethylene resin is a polytetrafluoroethylene dispersion resin with fiberizing properties, and the coverage of the surface of the particles by the filler is between 50% and 100%. This polytetrafluoroethylene composition can produce molded articles that fully utilize the properties of the filler. Furthermore, the composition can provide molded articles that have minimal defects such as scratches, fractures, cracks, and holes, and exhibit excellent strength and durability.

[0028] In the polytetrafluoroethylene composition, the polytetrafluoroethylene resin particles preferably have an average particle size of 250 μm to 800 μm.

[0029] In the polytetrafluoroethylene composition, the average particle size of the filler is preferably smaller than the average particle size of the polytetrafluoroethylene resin particles.

[0030] In the polytetrafluoroethylene composition, the filler is preferably a functional filler or a color powder, and the functional filler is an organic filler or an inorganic filler. The organic filler is one or more selected from aramid fiber, polyphenylene ester, polyphenylene sulfide, polyimide, polyetheretherketone, polyphenylene, polyamide and wholly aromatic polyester resin, and the inorganic filler is one or more selected from metal powder, graphite, carbon black, coke, carbon powder, carbon fiber, graphene, carbon nanotubes, ceramic powder, talc, mica, aluminum oxide, zinc oxide, tin oxide, titanium oxide, silicon dioxide, calcium carbonate, calcium oxide, magnesium oxide, potassium titanate, glass fiber, glass flakes, glass beads, silicon carbide, calcium fluoride, boron nitride, barium sulfate, molybdenum disulfide and potassium carbonate whiskers.

[0031] More preferably, the filler is a functional filler or a color powder, the functional filler is an organic filler or an inorganic filler, the organic filler is one or more selected from polyphenylene ester, polyphenylene sulfide, polyimide, polyetheretherketone, polyphenylene, polyamide and wholly aromatic polyester resin, and the inorganic filler is one or more selected from metal powder, graphite, carbon black, coke, carbon powder, graphene, carbon nanotubes, ceramic powder, talc, mica, aluminum oxide, zinc oxide, tin oxide, titanium oxide, silicon dioxide, calcium carbonate, calcium oxide, magnesium oxide, potassium titanate, glass flakes, glass beads, silicon carbide, calcium fluoride, boron nitride, barium sulfate, molybdenum disulfide and potassium carbonate whiskers.

[0032] In the polytetrafluoroethylene composition, the content of the filler is preferably 0.1% by weight or more and 60% by weight or less based on the total amount of the polytetrafluoroethylene resin particles and the filler.

[0033] The polytetrafluoroethylene composition is preferably in powder form.

[0034] The polytetrafluoroethylene composition preferably has an average particle size of 250 μm to 1000 μm.

[0035] The present invention also relates to a molded article, a conductive tube, a thermally conductive film, and a CCL substrate obtained by using the polytetrafluoroethylene composition. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is an optical microscope photograph (magnification: 200 times) of PTFE-carbon black composite particles obtained by mechanical mixing in the conventional technology (Comparative Example 1).

[0037] Figure 2 This is an optical microscope photograph (magnification: 200 times) of PTFE-carbon black composite particles obtained by wet mixing according to the prior art (Comparative Example 2).

[0038] Figure 3This is an optical microscope photograph of the PTFE before mixing used in Examples 1 to 5 (magnification: 200 times).

[0039] Figure 4 These are optical microscope photographs of PTFE-carbon black composite particles obtained by the production method of Example 1, (a) is a photograph at a magnification of 200 times, and (b) is a photograph at a magnification of 350 times.

[0040] Figure 5 This is an optical microscope photograph of PTFE-carbon black composite particles obtained by the production method of Example 2 (magnification: 200 times).

[0041] Figure 6 This is an optical microscope photograph of PTFE-carbon black composite particles obtained by the production method of Example 3 (magnification: 200 times).

[0042] Figure 7 These are optical microscope photographs of PTFE-carbon black composite particles obtained by the production method of Example 4, (a) is a photograph at a magnification of 200 times, and (b) is a photograph at a magnification of 350 times.

[0043] Figure 8 This is an optical microscope photograph of PTFE-carbon black composite particles obtained by the production method of Example 5 (magnification: 200 times).

[0044] Figure 9 This is an optical microscope photograph of the PTFE-carbon fiber composite particles obtained by the production method of Example 6 (magnification: 200 times).

[0045] Figure 10 This is an optical microscope photograph of the conductive tube obtained in Example A (magnification: 8000 times).

[0046] Figure 11 This is an optical microscope photograph (magnification: 8000 times) of the conductive tube obtained in Comparative Example A'.

[0047] Figure 12 This is an optical microscope photograph (magnification: 8000 times) of the conductive tube obtained in Comparative Example A".

[0048] Figure 13 These are optical microscope photographs of the thermally conductive film obtained in Example B, (a) is a photograph at a magnification of 50 times, and (b) is a photograph at a magnification of 600 times.

[0049] Figure 14 These are optical microscope photographs of the thermally conductive film obtained in Comparative Example B′, (a) is a photograph at a magnification of 50 times, and (b) is a photograph at a magnification of 600 times.

[0050] Figure 15 It is a schematic cross-sectional view showing an example of a pulse-type airflow mixer.

[0051] Figure 16 This is an image obtained by binarizing the video microscope photograph of the composition obtained in Example 1.

[0052] Figure 17 This is an image obtained by binarizing the video microscope photograph of the composition obtained in Comparative Example 1.

[0053] Figure 18 This is an image obtained by binarizing the video microscope photograph of the composition obtained in Comparative Example 2.

[0054] Figure 19 (a) is an electron micrograph of the composition obtained in Example 8, (b) is an elemental mapping image obtained by performing elemental mapping of fluorine using the electron micrograph, and (c) is an image obtained by binarizing the elemental mapping image.

[0055] Figure 20 (a) is an electron micrograph of the composition obtained in Comparative Example 3, (b) is an elemental mapping image obtained by performing elemental mapping of fluorine using the electron micrograph, and (c) is an image obtained by binarizing the elemental mapping image. DETAILED DESCRIPTION

[0056] In the production method of the present invention, a polytetrafluoroethylene (PTFE) resin and a filler are mixed using an air flow mixer to obtain a polytetrafluoroethylene composition including the polytetrafluoroethylene resin and the filler uniformly mixed.

[0057] In the manufacturing method of the present invention, a pneumatic mixer is used to mix the polytetrafluoroethylene resin and filler. The principle is that compressed air is instantly injected from the bottom of the mixer, causing the raw materials in the mixing chamber to boil and initiate thorough mixing. The injected air is then discharged through a dust collector above. Because the pneumatic mixer uses no mechanical transmission or shear force during the mixing process, it is particularly suitable for dispersing PTFE. The compressed air can also disaggregate clumped or agglomerated materials. Thus, the manufacturing method of the present invention produces a polytetrafluoroethylene composition in which the polytetrafluoroethylene resin and filler are uniformly mixed and not prone to agglomeration.

[0058] In other words, according to the production method of the present invention, polytetrafluoroethylene can be mixed with a filler without excessively fibrillating the polytetrafluoroethylene, and a polytetrafluoroethylene composition in which polytetrafluoroethylene and the filler are uniformly mixed can be obtained.

[0059] In the production method of the present invention, the filler is preferably coated on the surface of the polytetrafluoroethylene resin particles. Because the present invention utilizes an airflow mixer for mixing, the shear-sensitive polytetrafluoroethylene resin is prevented from excessive fiberization, enabling more uniform mixing of the polytetrafluoroethylene resin and the filler, while also allowing the filler to be evenly coated on the surface of the polytetrafluoroethylene resin particles.

[0060] The polytetrafluoroethylene (PTFE) resin preferably has a fiberizing property, wherein the fiberizing property refers to a property of being easily fiberized to form fibrils.

[0061] The presence or absence of fibrosis can be determined by paste extrusion, a representative method for molding a powder (dispersion resin, i.e., fine powder) made from an emulsified polymer of tetrafluoroethylene (TFE), namely, "high molecular weight PTFE powder." Paste extrusion is generally possible because high molecular weight PTFE powder has fibrosis. If the unfired molded article obtained by paste extrusion lacks substantial strength and elongation, for example, if the elongation is 0% and the article breaks when stretched, it can be considered to have no fibrosis.

[0062] The PTFE resin preferably has non-melt secondary processability, which means that the melt index cannot be measured at a temperature higher than the crystalline melting point according to ASTM D-1238 and D-2116.

[0063] The PTFE resin may be in granular form or powder form.

[0064] In the production method of the present invention, the polytetrafluoroethylene resin may be a PTFE dispersion resin or a PTFE suspension resin, but preferably the polytetrafluoroethylene resin is a PTFE dispersion resin. Generally, PTFE dispersion resins are more susceptible to shear forces and become fibrillated, but the production method of the present invention does not involve shear forces, making it more suitable for mixing PTFE dispersion resins with fillers.

[0065] PTFE dispersion resin is formed by coagulation drying of a dispersion formed by emulsion polymerization. The PTFE dispersion resin in the present invention can be produced according to known methods, or commercially available polytetrafluoroethylene dispersion resins can be used. Examples of commercially available PTFE dispersion resins include POLYFLON PTFE F-104, F-208, and F-302 manufactured by Daikin Industries, Ltd.

[0066] The PTFE dispersion resin may be a PTFE fine powder. The PTFE fine powder is obtained by emulsifying and polymerizing TFE to obtain a PTFE aqueous dispersion, and then agglomerating the PTFE primary particles in the PTFE aqueous dispersion to obtain a powder (secondary particles). The PTFE fine powder may also be obtained by granulating the particles obtained by polymerization using a known method.

[0067] The average particle size of the PTFE dispersed resin is preferably 250 μm or more and 800 μm or less, and more preferably 300 μm or more and 600 μm or less.

[0068] The standard specific gravity (SSG) of the PTFE dispersion resin is preferably from 2.13 to 2.28, more preferably from 2.14 to 2.20. The apparent density of the PTFE dispersion resin is preferably from 400 g / L to 600 g / L. The compression ratio (RR) of the PTFE dispersion resin is preferably from 20 to 3500, more preferably from 100 to 3500. The compression ratio is the ratio of the cross-sectional area of ​​the resin in the extrusion cylinder (S1) to the cross-sectional area of ​​the resin at the die (S2).

[0069] The average particle size of the PTFE suspension resin is preferably 15 μm to 200 μm. The apparent density of the PTFE suspension resin is preferably 300 g / L to 600 g / L. The standard specific gravity of the PTFE suspension resin is preferably 2.13 to 2.28, more preferably 2.14 to 2.20.

[0070] The PTFE suspension resin may be a PTFE molding powder. The PTFE molding powder is a powder obtained by suspension polymerization of TFE. The PTFE molding powder may also be obtained by granulating the particles obtained by polymerization using a known method.

[0071] The average particle size of the PTFE resin is measured according to JIS K 6891. The average particle size may be the average particle size of PTFE secondary particles.

[0072] The SSG of the PTFE resin is measured by a water displacement method based on ASTM D-792 using a sample molded according to ASTM D 4895-89.

[0073] The apparent density of the PTFE resin is measured in accordance with JIS K6891 (in the case of a suspended resin, ie, compression powder) or JIS K6892 (in the case of a dispersed resin, ie, fine powder).

[0074] The PTFE resin preferably has a melting point of 324 to 360°C. The melting point is the first melting point, which is the temperature corresponding to the maximum value in the heat of fusion curve of PTFE that has not been heated to a temperature of 300°C or higher, measured at a rate of 10°C / minute using a differential scanning calorimeter (DSC).

[0075] The PTFE resin may be a TFE homopolymer consisting solely of tetrafluoroethylene (TFE), or may be a modified PTFE comprising a TFE unit and a modifying monomer unit based on a modifying monomer copolymerizable with TFE.

[0076] The modifying monomer is not particularly limited as long as it is copolymerizable with TFE. Examples thereof include perfluoroolefins such as hexafluoropropylene (HFP); perhalogenated olefins such as chlorotrifluoroethylene (CTFE); hydrogen-containing fluoroolefins such as trifluoroethylene and vinylidene fluoride (VDF); perfluorovinyl ether; (perfluoroalkyl)ethylene; ethylene; and fluorinated vinyl ethers having a nitrile group. The modifying monomers used may be either one or more.

[0077] The perfluorovinyl ether is not particularly limited, and examples thereof include perfluorounsaturated compounds represented by the following general formula (1).

[0078] CF2=CF-ORf 1 (1)

[0079] (Where Rf 1 represents a perfluorinated organic group.)

[0080] In this specification, the "perfluoroorganic group" refers to an organic group in which all hydrogen atoms bonded to carbon atoms are replaced by fluorine atoms. The perfluoroorganic group may have an ether oxygen.

[0081] Examples of the perfluorovinyl ether include Rf in the general formula (1). 1 Perfluoro(alkyl vinyl ether) (PAVE) having a perfluoroalkyl group having 1 to 10 carbon atoms. The perfluoroalkyl group preferably has 1 to 5 carbon atoms.

[0082] Examples of the perfluoroalkyl group in PAVE include perfluoromethyl, perfluoroethyl, perfluoropropyl, perfluorobutyl, perfluoropentyl, and perfluorohexyl. Perfluoropropyl vinyl ether (PPVE) in which the perfluoroalkyl group is perfluoropropyl is preferred.

[0083] As the perfluorovinyl ether, further examples include Rf in the above general formula (1): 1 is a perfluorovinyl ether of a perfluoro(alkoxyalkyl) group having 4 to 9 carbon atoms, Rf 1Perfluorovinyl ether of a group represented by the following formula (2), Rf 1 Perfluorovinyl ether, etc., which are groups represented by the following formula (3).

[0084]

[0085] (In the formula, m represents 0 or an integer from 1 to 4.)

[0086]

[0087] (In the formula, n represents an integer from 1 to 4.)

[0088] The perfluoroalkylethylene is not particularly limited, and examples thereof include perfluorobutylethylene (PFBE) and perfluorohexylethylene (PFHE).

[0089] As the fluorine-containing vinyl ether having a nitrile group, CF2=CFORf is more preferable. 2 CN (where Rf 2 represents an alkylene group having 2 to 7 carbon atoms, which may have an oxygen atom inserted between two carbon atoms. ) represents a fluorine-containing vinyl ether represented by.

[0090] The modifying monomer in the modified PTFE is preferably at least one monomer selected from HFP, CTFE, VDF, PPVE, PFBE, and ethylene, and more preferably at least one monomer selected from HFP and CTFE.

[0091] The polymerized unit based on the modified monomer (modified monomer unit) is preferably in the range of 0.00001 to 1.0 mass %. As the lower limit of the modified monomer unit, it is preferably 0.0001 mass %, more preferably 0.0005 mass %, and further preferably 0.001 mass %. As the upper limit of the modified monomer unit, it is preferably 0.90 mass %, more preferably 0.50 mass %, further preferably 0.40 mass %, further more preferably 0.30 mass %, particularly more preferably 0.10 mass %, particularly preferably 0.08 mass %, particularly preferably 0.05 mass %, and particularly preferably 0.01 mass %.

[0092] In this specification, the modified monomer unit refers to a part of the molecular structure of PTFE and is a part derived from a modified monomer.

[0093] In this specification, the content of each monomer constituting PTFE can be calculated by appropriately combining NMR, FT-IR, elemental analysis, and fluorescent X-ray analysis depending on the type of monomer.

[0094] In the manufacturing method of the present invention, a "filler" is a powdery substance used to improve various physical properties of the molded product, and a functional filler or color powder can be used. The functional filler can be various organic fillers or inorganic fillers. Examples of organic fillers include engineering plastics such as aramid fiber, polyphenylene ester (POB), polyphenylene sulfide (PPS), polyimide (PI), polyetheretherketone (PEEK), polyphenylene, polyamide, and wholly aromatic polyester resins, with polyphenylene ester (POB), polyphenylene sulfide (PPS), polyimide (PI), polyetheretherketone (PEEK), polyphenylene, polyamide, and wholly aromatic polyester resins being preferred. As inorganic filler, metal powder, graphite, carbon black, coke, carbon powder, carbon fiber, Graphene, carbon nanotube, ceramic powder, talcum powder, mica, aluminum oxide, zinc oxide, tin oxide, titanium oxide, silicon dioxide, calcium carbonate, calcium oxide, magnesium oxide, potassium titanate, glass fiber, glass flake, glass bead, silicon carbide, calcium fluoride, boron nitride (BN), barium sulfate, molybdenum disulfide and potassium carbonate whisker etc. can be enumerated, preferably metal powder, graphite, carbon black, coke, carbon powder, Graphene, carbon nanotube, ceramic powder, talcum powder, mica, aluminum oxide, zinc oxide, tin oxide, titanium oxide, silicon dioxide, calcium carbonate, calcium oxide, magnesium oxide, potassium titanate, glass flake, glass bead, silicon carbide, calcium fluoride, boron nitride (BN), barium sulfate, molybdenum disulfide and potassium carbonate whisker.Also can as required different filler combinations be used.In addition, even if it is the filler of same kind, also can shape or size different filler combinations be used.

[0095] The filler may be an inorganic filler, or one or more selected from carbon-based inorganic fillers and ceramic powders, or one or more selected from graphite, carbon black, carbon fiber and ceramic powders, or one or more selected from graphite, carbon black and ceramic powders.

[0096] The filler may be in granular form or in fibrous form, and is preferably in granular form.

[0097] The particle size of the filler is preferably from 10 nm to 100 μm, more preferably from 10 nm to 50 μm, thereby enabling more uniform mixing.

[0098] The particle size of the filler may be an average particle size, and can be measured by a known measurement method, such as an imaging method, a sieving method, a light scattering method, etc., depending on the type of the filler.

[0099] The average particle size of the filler is preferably smaller than the average particle size of the polytetrafluoroethylene resin particles, so that the surface of the polytetrafluoroethylene resin particles can be more uniformly coated with the filler.

[0100] The filler preferably has an aspect ratio of 50 or less. This allows the filler to more uniformly coat the surface of the polytetrafluoroethylene resin particles. The aspect ratio is more preferably 30 or less, further preferably 20 or less, and particularly preferably 10 or less.

[0101] The aspect ratio is obtained by observing the filler with a scanning electron microscope (SEM), performing image processing on 10 or more randomly selected particles, and averaging the ratio of the major axis to the minor axis.

[0102] In view of the performance of the final molded product, the amount of filler added is preferably 0.1% by weight or more, more preferably 1% by weight or more, relative to the total amount of the polytetrafluoroethylene resin and the filler added, and is preferably 60% by weight or less, more preferably 20% by weight or less.

[0103] The added amount is 0.1 wt% to 60 wt% relative to the total added amount of the polytetrafluoroethylene resin and the filler, more preferably 1 wt% to 60 wt%, and even more preferably 1 wt% to 20 wt%.

[0104] Furthermore, the amount of filler added can be appropriately set depending on the type of filler. For example, when the filler is graphite, the amount added is preferably 15% by weight or more and 25% by weight or less; when the filler is carbon fiber, the amount added is preferably 10% by weight or more and 25% by weight or less; when the filler is carbon black, the amount added is preferably 1% by weight or more and 10% by weight or less; when the filler is glass fiber, the amount added is preferably 15% by weight or more and 30% by weight or less; when the filler is molybdenum disulfide, the amount added is preferably 0.1% by weight or more and 5% by weight or less; when the filler is ceramic powder, the amount added is preferably 20% by weight or more and 60% by weight or less; when the filler is copper powder, the amount added is preferably 30% by weight or more and 60% by weight or less; when the filler is POB, the amount added is preferably 0.1% by weight or more and 0.1% by weight or less. When the filler is PI, the addition amount is preferably from 5% to 15% by weight; when the filler is PPS, the addition amount is preferably from 10% to 30% by weight; when the filler is PEEK, the addition amount is preferably from 5% to 20% by weight; when the filler is glass beads, the addition amount is preferably from 10% to 30% by weight; when the filler is BN, the addition amount is preferably from 5% to 15% by weight; when the filler is stainless steel powder, the addition amount is preferably from 30% to 60% by weight; when the filler is carbon powder, the addition amount is preferably from 15% to 25% by weight.

[0105] In a preferred embodiment of the manufacturing method of the present invention, the loading coefficient of the PTFE and filler is within a range of 0.2 to 0.6. If the loading coefficient is too large, there will be insufficient mixing space, affecting the mixing effect. If the loading coefficient is too small, the spatial density of the PTFE and filler within the mixing chamber will be low, resulting in a low contact probability and affecting mixing efficiency. The loading coefficient is the ratio of the material filling volume to the mixing chamber volume required for the mixer to achieve the desired mixing effect.

[0106] In the manufacturing method of the present invention, the airflow mixer can be a pulsed airflow mixer, an airflow blender, an airflow pulverizer, or any other type of airflow mixer. Airflow mixers lack a stirring device and are suitable for polytetrafluoroethylene dispersion resins that are sensitive to shear forces, thereby reducing agglomeration due to fiberization and other factors. Pulsed airflow mixers are preferred. Thus, gas enters the mixing chamber in a pulsed manner, dispersing the materials and, in particular, increasing the contact area between the materials. The high-speed gas can also deagglomerate agglomerated or agglomerated materials, thereby facilitating mixing of the materials.

[0107] An example of a pulse-type airflow mixer will be described with reference to the drawings, but the pulse-type airflow mixer that can be used in the production method of the present invention is not limited thereto.

[0108] Figure 15 It is a schematic cross-sectional view showing an example of a pulse-type airflow mixer. Figure 15 In the pulse airflow mixer shown, a raw material storage tank 4 is provided at the bottom of a mixing tank body 3 for airflow mixing. Raw materials such as PTFE resin and filler are fed from a raw material inlet (not shown) provided in the raw material storage tank 4.

[0109] The air used for airflow mixing is first compressed by an air compressor 10, then cooled and dried by a cooling dryer 9, and stored in a compressed air storage tank 8. The compressed air is supplied to the raw material storage tank 4 through a nozzle 5 under pulse conditions controlled by a pulse controller 7. The raw materials stored in the raw material storage tank 4 are sprayed up by the supplied compressed air and mixed within the mixing tank body 3. The temperature within the mixing tank body 3 can be adjusted by a temperature control device 6.

[0110] A filter device 2 is provided on the top of the mixing tank body 3, from which the air for air flow mixing is discharged. The air discharged from the mixing tank body 3 is discharged to the outside through the exhaust device 1.

[0111] When using a pulsed air flow mixer, preferably in the mixing step, the pulse interval of the pulsed air flow mixer is adjusted to more than 5 seconds and less than 30 seconds, more preferably more than 10 seconds and less than 30 seconds, further preferably more than 20 seconds and less than 30 seconds. If the pulse interval is too small, then there may be filler that does not fully settle, and just enters the next pulse, which can reduce the contact probability of filler and bottom PTFE, and reduce the effect of fully and evenly mixed. If the pulse interval is too large, then the time of overall mixing may be extended, reducing production efficiency.

[0112] When using a pulsed air flow mixer, the single pulse air flow time can be specifically set according to the apparent density of the filler. The greater the apparent density, the longer the time can be set. Preferably, in the mixing step, the single pulse air flow time of the pulsed air flow mixer is set to 0.8 seconds to 2 seconds, more preferably 0.8 seconds to 1.5 seconds. If the single pulse air flow time is too short, the probability of the PTFE at the bottom of the mixer participating in the mixing becomes smaller; if the single pulse air flow time is too long, the filler with a smaller apparent density tends to always float above, thereby reducing the effect of sufficient and uniform mixing.

[0113] When using a pulsed air flow mixer, the number of pulses can be set according to the loading factor, filler type, filler addition amount, filler specific surface area, etc. Preferably, in the mixing step, the number of pulses of the pulsed air flow mixer is set to 5 or more and 40 or less, more preferably 10 or more and 40 or less, and further preferably 15 or more and 40 or less. If the number of pulses is too small, the mixing may not be sufficient. If the number of pulses is too large, the mixing cycle may be extended, reducing the mixing efficiency.

[0114] In the manufacturing method of the present invention, during the mixing step, the air inlet pressure of the airflow mixer is preferably adjusted to a value between 0.4 MPa and 0.8 MPa, more preferably between 0.5 MPa and 0.8 MPa, and even more preferably between 0.6 MPa and 0.8 MPa. If the inlet pressure is less than 0.4 MPa, the raw materials are lifted to a low height by the airflow, resulting in insufficient mixing space and inadequate mixing. If the inlet pressure is greater than 0.8 MPa, the raw materials may adhere directly to the dust filter bags above the mixing chamber and not participate in the subsequent mixing process.

[0115] In the manufacturing method of the present invention, during the mixing step, the temperature of the air flow mixer is preferably controlled within a range of 5°C to 30°C, preferably 5°C to 25°C, and more preferably 5°C to 19°C. This allows the materials to be mixed in a low-temperature environment, reduces the fibrillation of the polytetrafluoroethylene resin, improves the fluidity of the particles, and enhances mixing efficiency.

[0116] In the manufacturing method of the present invention, preferably, during the mixing step, the air flow mixer is temperature controlled by circulating a coolant or using a refrigerated air dryer, thereby enabling better low temperature control and thus achieving a better mixing effect.

[0117] A preferred embodiment of the manufacturing method of the present invention includes the following steps: using a pulse airflow mixer, placing the materials into the air mixing chamber according to an appropriate loading factor; adjusting parameters such as the inlet pressure, pulse interval, single pulse airflow time, and number of pulses; turning on the temperature control system to lower the temperature of the mixing chamber to the temperature required for mixing; and starting mixing.

[0118] In the polytetrafluoroethylene composition (also referred to as the first PTFE composition) manufactured according to the manufacturing method of the present invention, the filler is evenly coated on the surface of the polytetrafluoroethylene particles, which does not affect subsequent processing and is conducive to improving the performance of the polytetrafluoroethylene.

[0119] In the manufacturing method of the present invention, preferably no organic solvent is used. In other words, preferably, neither the PTFE resin nor the filler is mixed with an organic solvent. The first PTFE composition preferably does not substantially contain an organic solvent. Thus, the adverse effects caused by residual organic solvents can be reduced. Specific examples of organic solvents are described in detail later.

[0120] The content of the organic solvent in the first PTFE composition is preferably 500 ppb by mass or less, more preferably 100 ppb by mass or less, even more preferably less than 100 ppb by mass, even more preferably 10 ppb by mass or less, and particularly preferably 1 ppb by mass or less, relative to the PTFE composition. The lower limit is not particularly limited and may be an amount less than the detection limit.

[0121] The organic solvent content can be measured by headspace GC / MS. Specifically, 1 g of a sample is heated at 200°C for 30 minutes and then measured using an Agilent 5977A (column DB-624). The detection limit of this method is 100 ppb by mass.

[0122] The present invention also relates to a polytetrafluoroethylene (PTFE) composition (also referred to as a second PTFE composition), which comprises particles of a polytetrafluoroethylene resin and a filler coating the surface of the particles, and contains substantially no organic solvent. The polytetrafluoroethylene resin is a polytetrafluoroethylene dispersion resin having fiberizing properties, and the coverage rate of the surface of the particles coated by the filler is greater than 50% and less than 100%.

[0123] Since the second PTFE composition has a surface coverage rate of 50% to 100% on the particles coated with the filler, it can provide molded articles that fully utilize the properties of the filler. Furthermore, it can provide molded articles that have few defects such as scratches, fractures, cracks, and holes, and exhibit excellent strength and durability.

[0124] The coverage is preferably 60% or more, more preferably 70% or more, even more preferably 80% or more, even more preferably 90% or more, and particularly preferably 95% or more.

[0125] The coverage ratio was calculated by binarizing a 200-fold magnification photograph taken using a video microscope (Video Microscope VHX-900 manufactured by KEYENCE) and then using the following method.

[0126] Coverage (%) = S2 / (S1+S2)×100

[0127] (Wherein, S1 represents the area of ​​the PTFE resin not covered by the filler, and S2 represents the area of ​​the PTFE resin covered by the filler.)

[0128] The image analysis software used for the binarization process is not particularly limited, and for example, free software Image J published by the National Institutes of Health (NIH) of the United States can be used.

[0129] The coverage of the second PTFE composition can also be measured using a scanning electron microscope (SEM) and elemental mapping.

[0130] Sometimes, calculating the coverage using an optical microscope photograph is difficult due to the mixing state of the PTFE resin and the filler and the filler's color. For example, if a filler smaller than the primary particles of the PTFE resin is dispersed and mixed between the primary particles of the PTFE resin (emulsified particles, particle size 1 μm or less), the boundaries between them cannot be discerned in the optical microscope photograph. In such cases, using SEM and elemental mapping methods to calculate the coverage is effective.

[0131] The coverage ratio based on the above SEM and elemental mapping can be obtained by performing elemental mapping of fluorine using a SEM (SU8020 Scanning Electron Microscope manufactured by HITACHI), imaging the image, binarizing the image, and calculating the coverage ratio using the same method as that used for calculating the coverage ratio from the video microscope image.

[0132] In the second PTFE composition, the PTFE resin constituting the particles is a PTFE dispersion resin having a fibrous property. Thus, the second PTFE composition has excellent fibrous properties and can provide a uniform pasty extrudate. The PTFE dispersion resin can be the same as the PTFE dispersion resin that can be used in the above-mentioned manufacturing method of the present invention.

[0133] The PTFE resin preferably has non-melt secondary processability. The non-melt secondary processability is as described above.

[0134] The PTFE resin particles may be secondary particles of PTFE resin.

[0135] The PTFE resin particles preferably have an average particle size of 250 μm to 800 μm, more preferably 300 μm to 600 μm.

[0136] As the filler in the second PTFE composition, the same filler as that which can be used in the above-mentioned production method of the present invention can be used.

[0137] The filler may be in granular form or in fibrous form, and is preferably in granular form.

[0138] The average particle size of the filler is preferably from 10 nm to 100 μm, more preferably from 10 nm to 50 μm.

[0139] The average particle size of the filler is preferably smaller than the average particle size of the PTFE resin particles.

[0140] The filler preferably has an aspect ratio of 50 or less, more preferably 30 or less, further preferably 20 or less, and particularly preferably 10 or less.

[0141] In the second PTFE composition, the content of the filler is preferably 0.1 wt% or more, more preferably 1 wt% or more, and preferably 60 wt% or less, more preferably 20 wt% or less, relative to the total amount of the polytetrafluoroethylene resin particles and the filler.

[0142] The content of the filler can be appropriately set according to the type of filler. The specific content range of each filler is as described above.

[0143] The second PTFE composition contains substantially no organic solvent, so problems caused by residual organic solvent are less likely to occur.

[0144] The organic solvent is not particularly limited, and examples thereof include water-soluble organic solvents, chlorinated hydrocarbons, and fluorinated hydrocarbons.

[0145] Specific examples of the above-mentioned organic solvents include alcohols such as methanol, ethanol, and propanol; ketones such as acetone, methyl ethyl ketone (MEK), and methyl isobutyl ketone (MIBK); hydrogen-containing chlorocarbons such as methyl chloride, dichloromethane, chloroform, and trichloroethylene; carbon tetrachloride; hydrogen-containing fluorocarbons such as 1,1,1,2-tetrafluoroethane, 1,1-difluoroethane, 1,1,1,3,3-pentafluoropropane, and 1,1,1,2,3,3-hexafluoropropane; hydrogen-containing chlorofluorocarbons such as 1,1-dichloro-1-fluoroethane, 1,1-dichloro-2,2,3,3,3-pentafluoropropane, 1,3-dichloro-1,1,2,2,3-pentafluoropropane, and 1,1-dichloro-3,3,3-trifluoroethane.

[0146] The content of the organic solvent in the second PTFE composition is preferably 500 ppb by mass or less, more preferably 100 ppb by mass or less, even more preferably less than 100 ppb by mass, even more preferably 10 ppb by mass or less, and particularly preferably 1 ppb by mass or less, relative to the PTFE composition. The lower limit is not particularly limited and may be an amount less than the detection limit.

[0147] The organic solvent content can be measured by headspace GC / MS. Specifically, 1 g of a sample is heated at 200°C for 30 minutes and then measured using an Agilent 5977A (column DB-624). The detection limit of this method is 100 ppb by mass.

[0148] The second PTFE composition is preferably in powder form.

[0149] When the second PTFE composition is in powder form, the average particle size is preferably 250 μm or more, more preferably 300 μm or more, and even more preferably 400 μm or more, and is preferably 1000 μm or less, more preferably 800 μm or less, and even more preferably 600 μm or less.

[0150] The above-mentioned average particle size is measured in accordance with JIS K6891.

[0151] The extrusion pressure of the second PTFE composition at a compression ratio (RR: Reduction Ratio) of 400 is preferably 60 MPa or less, more preferably 50 MPa or less, and preferably 10 MPa or more.

[0152] The extrusion pressure is measured by the following method. 12.3 g of Isopar-G (ExxonMobil), a hydrocarbon oil, is added to 60 g of the PTFE composition as an extrusion aid. The mixture is uniformly mixed in a sealed container and aged at room temperature (25 ± 2°C) for 1 hour. The mixture is then placed in the barrel of an extruder conforming to ASTM D 4895 (equipped with a die having a compression ratio of 400). After holding the mixture at room temperature for 1 minute, a load of 5.7 MPa is immediately applied to the piston inserted into the barrel, and the mixture is extruded from the orifice at room temperature at a punching speed of 20 mm / min. The extrusion pressure (MPa) is calculated by dividing the load (N) at the moment the pressure reaches equilibrium during the extrusion operation by the cross-sectional area of ​​the barrel.

[0153] The second PTFE composition can be produced by the above-mentioned production method of the present invention.

[0154] The first and second PTFE compositions are molded to obtain a molded article. The molding method is not particularly limited, and a known method can be used.

[0155] The first and second PTFE compositions can be used in the manufacture of conductive tubes, thermally conductive films, CCL substrates, battery electrodes, PTFE pre-pigments, etc. Wherein, "CCL" refers to copper-clad laminate.

[0156] Specifically, the conductive tube can be produced using the first and second polytetrafluoroethylene compositions by known methods. For example, the first and second polytetrafluoroethylene compositions can be uniformly mixed with an additive, aged at a predetermined temperature for a predetermined time, and then formed into a tube. Compared to conductive tubes produced using polytetrafluoroethylene compositions produced by mechanical mixing or coagulation mixing, conductive tubes produced using the first and second polytetrafluoroethylene compositions have a higher yield rate, a smooth tube wall, a continuous and uniform conductive layer, and excellent conductivity.

[0157] Alternatively, the first and second polytetrafluoroethylene compositions can be used to produce a thermally conductive film using known methods. For example, the first and second polytetrafluoroethylene compositions are uniformly mixed with an additive, aged at a specified temperature for a specified time, and then preformed. The resulting composition is then extruded into a rod using an extruder, followed by roller calendering to produce the thermally conductive film. Compared to thermally conductive films produced using polytetrafluoroethylene compositions produced by mechanical mixing, thermally conductive films produced using the first and second polytetrafluoroethylene compositions have a higher yield, a smoother surface, more stable and uniform conductivity and heat generation, significantly improved mechanical strength, and a longer service life.

[0158] Further, the first and second polytetrafluoroethylene compositions can be used to obtain CCL substrates by a known method. For example, the first and second polytetrafluoroethylene compositions are uniformly mixed with an auxiliary agent, and after being cured for a specified time at a specified temperature, pre-molded, and then extruded into a rod using an extruder, followed by roller calendering to form a film, and multiple obtained films are thermally laminated, thereby manufacturing CCL substrates. Compared with the CCL substrates obtained using the polytetrafluoroethylene composition manufactured according to mechanical mixing, the stability and dimensional stability of the dielectric properties of the CCL substrates obtained using the first and second polytetrafluoroethylene compositions have been significantly improved.

[0159] Conductive tubes can be used in conductive oil pipes for automobiles and other applications, thermal conductive films can be used in automobile heated seat cushions and other applications, and CCL substrates can be used in the printed circuit board industry and other applications.

[0160] Example

[0161] Example 1

[0162] As the mixed raw materials, PTFE resin with a particle size of about 550μm and carbon black with a particle size of 50nm as the filler are used. The optical microscope photo of PTFE before mixing is as follows: Figure 3 As shown. Put PTFE resin and carbon black into the mixing chamber of the pulse airflow mixer so that the loading factor is 0.2. The amount of carbon black added is 3% by weight of the total amount of PTFE and carbon black added. Close the mixing chamber, then adjust the air inlet pressure to 0.4MPa, adjust the pulse interval to 20 seconds, set the single pulse airflow time to 0.8 seconds, and set the number of pulses to 20 times. Then, turn on the temperature control system (coolant circulation) to lower the mixing chamber temperature to 19°C. After the parameters are set, start mixing. After mixing is completed, turn off the air pump, open the mixing chamber, and discharge the material.

[0163] The optical microscope photograph of the particles in the mixed composition obtained in Example 1 is as follows: Figure 4 As shown, it can be clearly seen that the carbon black is evenly coated on the PTFE surface after mixing.

[0164] Example 2

[0165] The same procedure as in Example 1 was followed except that the loading factor, intake pressure, pulse interval, single pulse airflow time, pulse number, and mixing temperature were changed to the values ​​shown in Table 1.

[0166] The optical microscope photograph of the particles in the mixed composition obtained in Example 2 is as follows: Figure 5 As shown, it can be clearly seen that the carbon black is evenly coated on the PTFE surface after mixing.

[0167] Example 3

[0168] The same procedure as in Example 1 was followed except that the loading factor, intake pressure, pulse interval, single pulse airflow time, pulse number, and mixing temperature were changed to the values ​​shown in Table 1.

[0169] The optical microscope photograph of the particles in the mixed composition obtained in Example 3 is as follows: Figure 6 As shown, it can be clearly seen that the carbon black is evenly coated on the PTFE surface after mixing.

[0170] Example 4

[0171] The same procedure as in Example 1 was followed except that the loading factor, intake pressure, pulse interval, single pulse airflow time, pulse number, and mixing temperature were changed to the values ​​shown in Table 1.

[0172] The optical microscope photograph of the particles in the mixed composition obtained in Example 4 is as follows: Figure 7 As shown, it can be clearly seen that the carbon black is evenly coated on the PTFE surface after mixing.

[0173] Example 5

[0174] The same procedure as in Example 1 was followed except that the loading factor, intake pressure, pulse interval, single pulse airflow time, pulse number, and mixing temperature were changed to the values ​​shown in Table 1.

[0175] The optical microscope photograph of the particles in the mixed composition obtained in Example 5 is as follows: Figure 8 As shown, it can be clearly seen that the carbon black is evenly coated on the PTFE surface after mixing.

[0176] Table 1

[0177]

[0178] Example 6

[0179] As the mixed raw materials, PTFE resin with a particle size of about 28μm and carbon fiber as filler (diameter 10 microns, average aspect ratio 10:1) are used. PTFE resin and carbon fiber are placed in the mixing chamber of the pulse airflow mixer so that the loading coefficient is 0.3. The amount of carbon fiber added is 15% by weight of the total amount of PTFE and carbon fiber added. Close the mixing chamber, then adjust the air inlet pressure to 0.6MPa, adjust the pulse interval to 5 seconds, set the single pulse airflow time to 1.5 seconds, and set the number of pulses to 10 times. Next, turn on the temperature control system (coolant circulation) to lower the mixing chamber temperature to 15°C. After the parameters are set, start mixing. After mixing is completed, turn off the air pump, open the mixing chamber, and discharge the material.

[0180] The optical microscope photograph of the particles in the mixed composition obtained in Example 6 is as follows: Figure 9As shown, it can be clearly seen that the PTFE resin particles and carbon fibers are evenly mixed.

[0181] Table 2

[0182]

[0183] Example 7

[0184] As the mixing raw materials, PTFE resin with a particle size of about 550 μm and carbon black with a particle size of 50 nm as a filler are used. The PTFE resin and carbon black are placed in the mixing chamber of the pulse airflow mixer so that the loading coefficient is 0.4. The amount of carbon black added is 3% by weight of the total amount of PTFE and carbon black added. The mixing chamber is closed, and then the air inlet pressure is adjusted to 0.6 MPa, the pulse interval is adjusted to 25 seconds, the single pulse airflow time is set to 1.2 seconds, and the number of pulses is set to 30 times. Then, the temperature control system is turned on to lower the mixing chamber temperature to 19°C. After the parameter setting is completed, mixing is started. After the mixing is completed, the air pump is turned off, the mixing chamber is opened, and the material is discharged. In this way, the PTFE composition of Example 7 can be obtained.

[0185] Example 8

[0186] As mixed raw materials, PTFE resin with a particle size of about 550μm, conductive carbon black with a particle size of 36nm as a filler, and graphite with a particle size of 26μm as a filler are used. PTFE resin, conductive carbon black and graphite are placed in the mixing chamber of a pulsed airflow mixer so that the loading coefficient is 0.5. The amount of conductive carbon black added is 15% by weight of the total amount of PTFE, conductive carbon black and graphite added, and the amount of graphite added is 10% by weight of the total amount of PTFE, conductive carbon black and graphite added. The mixing chamber is closed, and the air intake pressure is adjusted to 0.5MPa, the pulse interval is adjusted to 30 seconds, the single pulse airflow time is set to 1.2 seconds, and the number of pulses is set to 30 times. Then, the temperature control system (coolant circulation) is turned on to reduce the temperature of the mixing chamber to 19°C. After the parameter setting is completed, mixing is started. After mixing is completed, the air pump is turned off, the mixing chamber is opened, and the material is discharged. Thus, the PTFE composition of Example 8 can be obtained.

[0187] Example 9

[0188] As a mixed raw material, a PTFE resin with a particle size of about 550 μm and a ceramic powder with a particle size of 20 nm as a filler are used. The PTFE resin and ceramic powder are placed in the mixing chamber of a pulsed airflow mixer so that the loading coefficient is 0.35. The amount of ceramic powder added is 50% by weight of the total amount of PTFE and ceramic powder added. The mixing chamber is closed, and the air inlet pressure is adjusted to 0.7 MPa, the pulse interval is adjusted to 20 seconds, the single pulse airflow time is set to 1.5 seconds, and the number of pulses is set to 30 times. Then, the temperature control system (coolant circulation) is turned on to lower the temperature of the mixing chamber to 19°C. After the parameter setting is completed, mixing is started. After the mixing is completed, the air pump is turned off, the mixing chamber is opened, and the material is discharged. Thus, the PTFE composition of Example 9 can be obtained.

[0189] Table 3

[0190]

[0191] Comparative Example 1 (Mechanical Mixing)

[0192] Using the same PTFE resin and filler (carbon black) as in Example 1, add a 3% by mass ratio of PTFE resin and carbon black to the mixing chamber of a mechanical mixer equipped with a stirring mechanism, ensuring that the volume of the added materials does not exceed 1 / 3 of the mixing chamber volume. Adjust the angle and height of the spoiler and close the mixing chamber. Adjust the speed to 1200 rpm and mix for 120 seconds. After mixing is complete, discharge the material.

[0193] The optical microscope photograph of the particles in the mixed composition obtained in Comparative Example 1 is as follows: Figure 1 As shown, the PTFE resin is clearly fibrillated.

[0194] Comparative Example 2 (Coagulation Mixing)

[0195] Using the same PTFE resin and filler (carbon black) as in Example 1, add 3% by mass of carbon black to a mixture of alcohol and water (volume ratio of alcohol to water 1:2.5) and ultrasonically disperse to obtain a carbon black pre-dispersion. The carbon black pre-dispersion is mechanically stirred at a low speed. After two minutes, the PTFE dispersion stock solution is gently added. Stirring is continued for 3 minutes, then the speed is increased and a small amount of flocculant is added. A large amount of the mixture precipitates. Stirring is continued for 10 minutes before stopping. Filter to remove most of the solvent. Dry at a low temperature below 100°C for at least 24 hours to obtain the PTFE composition of Comparative Example 2.

[0196] The optical microscope photograph of the particles in the mixed composition obtained in Comparative Example 2 is as follows: Figure 2 As shown, it can be clearly seen that most of the carbon black is wrapped inside the PTFE resin.

[0197] The products described in Examples A to C below were prepared using the PTFE compositions prepared in Examples 7 to 9 above, respectively, and the properties of these products were evaluated according to the following methods.

[0198] <Performance Evaluation>

[0199] 1. Current value

[0200] In the present invention, a 500 mm length of the obtained conductive tube was cut, a DC voltage of 1000 V was applied to both ends of the conductive tube, and the current value at this time was measured using a multimeter.

[0201] Higher current values ​​indicate lower resistance and higher conductivity of the material.

[0202] 2. Volume resistivity

[0203] Volume resistivity is the resistance of a material to electric current per unit volume.

[0204] In the present invention, the volume resistivity of the thermally conductive film is measured according to the test standard GB / T1410-2006. Specifically, the thermally conductive film is made into a test piece of 70mm×50mm×0.13mm (a*b*h). Then, the test piece is placed on the test bench, the adjustment nut is tightened, and a voltage of 500V is applied. The resistance value R of the test piece is measured using an ST2258C digital four-probe tester. X Then, according to the formula ρ V =R X *a*b / h, calculate the volume resistivity, whose unit is Ω·cm.

[0205] A higher volume resistivity indicates a higher insulating property of the material, and thus a lower conductivity. In the present invention, the volume resistivity is preferably less than 0.8 Ω·cm.

[0206] 3. Tensile strength TS and elongation at break EL

[0207] Tensile strength indicates the ability of a material to resist permanent deformation and damage under external forces. Elongation at break indicates the ratio of the displacement of a specimen at break to its original length.

[0208] In the present invention, the tensile strength and elongation at break of the obtained thermally conductive film are measured using an Instron 3366 universal tensile testing machine in accordance with the test standard ASTM D4894. Specifically, after the thermally conductive film is made into a dumbbell-shaped test piece, the gauge length L0 is set, and the width a and thickness b of the test piece are measured. Then, it is placed on the fixture. After the displacement and stress are reset to zero, the test is started, and the film is stretched at a tensile speed of 50 mm / min until it breaks. The stress F and length L1 at the time of fracture are recorded. According to the formula: tensile strength TS = F / (a×b), elongation at break EL = (L1-L0) / L0×100%, the tensile strength and elongation at break are calculated.

[0209] A higher tensile strength indicates a higher mechanical strength of the material. A higher elongation at break indicates a higher toughness of the material. In the present invention, preferably the tensile strength is greater than 20 MPa and the elongation at break is greater than 200%.

[0210] 4. Temperature drift

[0211] Temperature drift refers to the relative average rate of change of dielectric constant when the temperature increases by 1°C within a certain temperature range (-50 to 150°C).

[0212] In this invention, the temperature drift of the CCL substrate was measured using an Agilent N5234A tester in accordance with the test standard IPC-TM-650 2.5.5.5. Specifically, a 30mm × 70mm × 0.8mm test piece was formed into the CCL substrate and secured to a fixture. The dielectric constant in the z-axis direction was measured at room temperature and 10GHz. This test was repeated 4-5 times, and the average value was taken. The test was then repeated at various temperatures within the -50°C to 150°C temperature range, and a graph of the dielectric constant versus temperature was generated. The slope of the resulting graph was calculated and used as the temperature drift.

[0213] The lower the absolute value of the temperature drift, the lower the rate of change of the dielectric constant with respect to temperature, and the more stable the dielectric performance in actual use.

[0214] 5. Thermal expansion coefficient

[0215] The coefficient of thermal expansion indicates the relative change in the size of an object for every 1°C increase in temperature.

[0216] In the present invention, the thermal expansion coefficient of the CCL substrate is measured according to the test standard IPC-TM-650 2.4. Specifically, the CCL substrate is made into a sample of 6.35 mm × 6.35 mm × 0.8 mm and the thermal expansion coefficient of the sample is measured by TMA static thermomechanical analysis.

[0217] A lower thermal expansion coefficient indicates a smaller dimensional change with increasing temperature, resulting in a higher dimensional stability in the product. In the present invention, the thermal expansion coefficient is preferably (x, y, z) < (50, 50, 100). Here, "(x, y, z)" means that for every 1°C increase in temperature, the length, width, and thickness increase by x ppm, y ppm, and z ppm, respectively. The same applies hereafter.

[0218] Example A

[0219] The PTFE composition obtained in Example 7 was used and mixed with the auxiliary oil Isopar-G *1 The mixture was uniformly mixed and aged at 40°C for 24 hours, and then formed into a tube. Thus, the conductive tube of Example A was obtained.

[0220] The PTFE tube extrusion equipment used in the molding process was manufactured by Tabata Co., Ltd. of Japan. The diameters of the steel cylinder / core rod were 100 / 20 mm, the diameters of the die / needle membrane were 10.5 / 8.3 mm, the RR ratio was 232, and the extrusion pressure during molding was 19 MPa.

[0221] The surface of the conductive tube obtained in Example A was observed using an optical microscope at a magnification of 8000 times to obtain an optical microscope photograph of the surface of the conductive tube. The obtained photograph is shown in FIG. Figure 10 In. From Figure 10 It can be clearly seen that the surface of the conductive tube obtained in Example A is smooth, the conductive layer is continuous and uniform, and there are no obvious scratches or faults.

[0222] In addition, the current value of the conductive tube obtained in Example A was measured. The obtained results are shown in Table 4.

[0223] *1: Produced by ExxonMobil, with a specific gravity of 0.748, a flash point of 440°C, and a boiling point of 167-176°C.

[0224] Comparative Example A'

[0225] A conductive tube of Comparative Example A' was obtained in the same manner as in Example A except that the PTFE composition obtained in Comparative Example 1 was used.

[0226] In the same manner as in Example A, an optical microscope photograph of the surface of the conductive tube of Comparative Example A' was obtained. The obtained photograph is shown in FIG. Figure 11 In. From Figure 11 It can be clearly seen that PTFE fiberization has occurred and there are small cracks, which will affect the service life and compressive strength of the pipe.

[0227] In addition, the current value of the conductive tube of Comparative Example A′ was measured in the same manner as in Example A, and the obtained results are shown in Table 4.

[0228] Comparative Example A

[0229] A conductive tube of Comparative Example A" was obtained in the same manner as in Example A except that the PTFE composition obtained in Comparative Example 2 was used.

[0230] In the same manner as in Example A, an optical microscope photograph of the surface of the conductive tube of Comparative Example A" was obtained. The obtained photograph is shown in FIG. Figure 12 In. From Figure 12 It can be clearly seen that there are a lot of white agglomerates and the surface is very uneven. This is because the carbon black is wrapped inside the PTFE resin.

[0231] In addition, the current value of the conductive tube of Comparative Example A′ was measured in the same manner as in Example A, and the obtained results are shown in Table 4.

[0232] Table 4

[0233] Measured current value Example A >400mA Comparative Example A' 200~300mA Comparative Example A No current

[0234] The results in Table 4 show that the conductive tube produced using the polytetrafluoroethylene composition produced by the production method of the present invention exhibits high, uniform, and stable current values, indicating superior conductivity. In contrast, the conductive tube produced using the polytetrafluoroethylene composition produced by the mechanical mixing method exhibits lower current values, indicating that the conductive tube obtained in Comparative Example A' has high resistance and poor conductivity. Furthermore, no current values ​​were detected for the tube produced using the polytetrafluoroethylene composition produced by the coagulation mixing method, indicating that this tube lacks conductivity and cannot be used as a conductive tube.

[0235] Since products made from polytetrafluoroethylene compositions produced by the coagulation mixing method do not have electrical conductivity, they also do not have thermal conductivity. Therefore, in the following experiments, polytetrafluoroethylene compositions produced by the coagulation mixing method were not used to produce thermally conductive films.

[0236] Example B

[0237] The PTFE composition obtained in Example 8 was used and mixed with the auxiliary oil Isopar-M *2 After uniform mixing and aging at 40°C for 24 hours, the mixture was preformed at a pressure of 3 MPa for 20 minutes. The mixture was then extruded into 11 mm diameter rods using an extruder at a pressure of approximately 5.2 MPa. This was then rolled into a 0.13 mm film, dried, and sintered to produce the PTFE thermally conductive film.

[0238] The surface of the thermally conductive film obtained in Example B was observed using an optical microscope at 50 times and 600 times magnification, respectively, to obtain optical microscope photographs of the surface of the thermally conductive film. The obtained photographs are shown in FIG. Figure 13 In. From Figure 13 It can be clearly seen that the surface of the thermal conductive film is smooth and uniform, and there are no holes.

[0239] In addition, the volume resistivity, tensile strength, elongation at break, and thermal expansion coefficient of the thermally conductive film obtained in Example B were measured. The results are also shown in Table 5.

[0240] *2: Produced by ExxonMobil, with a specific gravity of 0.79, a flash point of 92°C, and a boiling point of 225-254°C.

[0241] Comparative Example B'

[0242] A thermally conductive film of Comparative Example B' was obtained in the same manner as in Example B except that the PTFE composition obtained in Comparative Example 1 was used.

[0243] In the same manner as in Example B, an optical microscope photograph of the surface of the thermally conductive film of Comparative Example B' was obtained. The obtained photograph is shown in FIG. Figure 14 In. From Figure 14 It can be clearly seen that there is partial fibrosis and holes in some parts of the membrane surface, which will lead to insufficient mechanical strength, uneven overall heating, the risk of local overheating, and a shorter service life.

[0244] The volume resistivity, tensile strength, and elongation at break of the thermally conductive film obtained in Comparative Example B′ were measured. The obtained results are shown in Table 5.

[0245] Table 5

[0246]

[0247] The results in Table 5 indicate that the thermally conductive film produced using the polytetrafluoroethylene composition produced by the method of the present invention exhibits greater mechanical strength and toughness, resulting in a longer service life. Furthermore, it exhibits lower volume resistivity, higher heat generation efficiency, and more uniform heat generation. In contrast, the thermally conductive film produced using the polytetrafluoroethylene composition produced by the mechanical mixing method exhibits lower mechanical strength and higher volume resistivity, resulting in lower heat generation efficiency and a shorter service life.

[0248] Example C

[0249] The PTFE composition obtained in Example 9 was used and mixed with the auxiliary oil Isopar-M *2After uniform mixing and aging at 40°C for 24 hours, the preform is maintained at 3 MPa for 20 minutes. Next, an extruder is used to extrude the preform into a 16mm diameter rod at approximately 4 MPa. Next, a 0.165mm film is formed by roller pressing, followed by drying and sintering to form a PTFE membrane. Eight PTFE membranes of the same size are heat-laminated to produce a 0.8mm CCL substrate.

[0250] Next, the temperature drift and thermal expansion coefficient of the CCL substrate obtained in Example C were measured. The obtained results are shown in Table 6.

[0251] Comparative Example C'

[0252] A CCL substrate of Comparative Example C' was obtained in the same manner as in Example C, except that the PTFE composition obtained in Comparative Example 1 was used. The temperature drift and thermal expansion coefficient of the CCL substrate obtained in Comparative Example C' were then measured. The results are shown in Table 6.

[0253] Table 6

[0254]

[0255] The results in Table 6 indicate that the CCL substrate produced using the polytetrafluoroethylene composition manufactured using the manufacturing method of the present invention exhibits low temperature drift and a low thermal expansion coefficient. Therefore, in actual use, it exhibits more stable dielectric properties and dimensional stability, which is beneficial for improving signal transmission efficiency and reducing losses. Furthermore, it exhibits a better composite effect with copper foil.

[0256] Experiment 1

[0257] The PTFE compositions obtained in Example 1, Comparative Example 1, and Comparative Example 2, and the PTFE resins (raw materials of the PTFE compositions) used in Example 1 and Comparative Example 1 were evaluated for fiberization properties by a paste extrusion test.

[0258] 12.3 g of Isopar-G, a hydrocarbon oil, as an extrusion aid was added to 60 g of each PTFE composition, and the mixture was uniformly mixed in a sealed container and aged at room temperature (25±2° C.) for 1 hour.

[0259] Next, a paste extrusion test was conducted using an extruder conforming to ASTM D 4895 and a die with a compression ratio of 400. Specifically, the mixture was filled into the extruder barrel and held at room temperature for 1 minute. A load of 5.7 MPa was then applied to the piston inserted into the barrel, and the mixture was immediately extruded from the orifice at room temperature at a ram speed of 20 mm / min. The state of the extrudate (called a bead) extruded from the orifice was observed, and the extrusion pressure was measured.

[0260] The extrusion pressure (MPa) was obtained by dividing the load (N) at the time when the pressure reached an equilibrium state during the extrusion operation by the cross-sectional area of ​​the cylinder.

[0261] Uniform paste-like extrudates were obtained for the PTFE compositions obtained in Example 1 and Comparative Example 2. The extrusion pressure of the PTFE compositions obtained in Example 1 and Comparative Example 2 was only 20% higher than the extrusion pressure of the raw material PTFE resin (33 MPa).

[0262] On the other hand, the extrudate of the PTFE composition obtained in Comparative Example 1 was non-uniform, partially cracked, and warped. A tensile test of this extrudate (unfired) revealed that the non-uniform portions lacked substantial strength and elongation, and the extrudate broke.

[0263] Furthermore, the extrusion pressure of the PTFE composition obtained in Comparative Example 1 was found to increase from the initial stage of extrusion compared to the extrusion pressure of the raw material PTFE resin, indicating that the extrusion pressure was unstable and did not reach equilibrium. Therefore, the extrusion pressure could not be calculated.

[0264] The results of the paste extrusion test showed that the fiberizing properties of the PTFE compositions obtained in Example 1 (airflow mixing) and Comparative Example 2 (coagulation mixing) were comparable to those of the raw material PTFE resin, and excellent results were obtained.

[0265] On the other hand, the fibrillation properties of the PTFE composition obtained in Comparative Example 1 (mechanical mixing) were significantly poor.

[0266] Experiment 2

[0267] The PTFE compositions obtained in Example 1, Comparative Example 1, and Comparative Example 2 were analyzed for the organic solvent contained in the PTFE compositions by headspace GC / MS.

[0268] Specifically, 1 g of a sample was heat-treated at 200° C. for 30 minutes in a headspace, and then measured using Agilent's 5977A (column DB-624).

[0269] The results of the analysis showed that the PTFE compositions obtained in Example 1 and Comparative Example 1 contained no organic solvent (less than the detection limit). On the other hand, ethanol (1.0 mass ppm) was detected in the PTFE composition obtained in Comparative Example 2.

[0270] Comparative Example 3

[0271] According to Examples 4 and 5 described in Japanese Patent Application Laid-Open No. 8-253600, a PTFE composition comprising a PTFE resin, carbon black, and graphite was obtained.

[0272] The PTFE resin was an aqueous dispersion of the PTFE resin used in Example 8, and the conductive carbon black and graphite were the same as those in Example 8. The mixing ratio of the conductive carbon black and graphite was the same as in Example 8, with the amount of conductive carbon black added being 15% by weight relative to the total amount of PTFE, carbon black, and graphite added, and the amount of graphite added being 10% by weight relative to the total amount of PTFE, carbon black, and graphite added.

[0273] As the water-insoluble organic solvent, 1,1-dichloro-1-fluoroethane was used in the same manner as in JP-A-8-253600.

[0274] Experiment 3

[0275] The PTFE compositions obtained in Example 8 and Comparative Example 3 were analyzed for the organic solvent contained in the PTFE compositions by headspace GC / MS.

[0276] Specifically, 1 g of a sample was heat-treated at 200° C. for 30 minutes in a headspace, and then measured using Agilent's 5977A (column DB-624).

[0277] The analysis results showed that the PTFE composition obtained in Example 8 contained no organic solvent (less than the detection limit). On the other hand, 1,1-dichloro-1-fluoroethane was detected in the PTFE composition obtained in Comparative Example 3 (1.2 mass ppm).

[0278] Experiment 4

[0279] The coverage ratio of the PTFE composition obtained in each Example and Comparative Example was calculated. The results are shown in Table 7.

[0280] Table 7

[0281]

[0282] exist Figure 16 、 17 1 and 18 show images obtained by binarizing the video microscope photographs of the compositions obtained in Example 1, Comparative Example 1, and Comparative Example 2.

[0283] exist Figure 19(a), (b) and (c) show an electron micrograph of the composition obtained in Example 8, an elemental mapping image obtained by performing elemental mapping of fluorine using the electron micrograph, and an image obtained by binarizing the elemental mapping image.

[0284] exist Figure 20 (a), (b), and (c) show an electron micrograph of the composition obtained in Comparative Example 3, an elemental mapping image obtained by performing elemental mapping of fluorine using the electron micrograph, and an image obtained by binarizing the elemental mapping image.

Claims

1. A method for producing a polytetrafluoroethylene composition, characterized in that: The method comprises the steps of mixing polytetrafluoroethylene resin and filler by using an air flow mixer to obtain a polytetrafluoroethylene composition comprising the polytetrafluoroethylene resin and the filler.

2. The manufacturing method according to claim 1, wherein: In the polytetrafluoroethylene composition, the filler covers the surface of the polytetrafluoroethylene resin particles.

3. The manufacturing method according to claim 1 or 2, wherein: The air flow mixer is a pulse air flow mixer.

4. The manufacturing method according to claim 3, wherein: In the mixing step, the pulse interval of the pulse-type air flow mixer is adjusted to be not less than 5 seconds and not more than 30 seconds.

5. The manufacturing method according to claim 3 or 4, characterized in that: In the mixing step, the single pulse airflow time of the pulse airflow mixer is set to be not less than 0.8 seconds and not more than 2 seconds.

6. The manufacturing method according to any one of claims 3 to 5, wherein: In the mixing step, the pulse number of the pulse-type air flow mixer is set to 5 to 40 times.

7. The manufacturing method according to any one of claims 1 to 6, wherein: In the mixing step, the air inlet pressure of the air flow mixer is adjusted to be greater than or equal to 0.4 MPa and less than or equal to 0.8 MPa.

8. The manufacturing method according to any one of claims 1 to 7, wherein: In the mixing step, the temperature of the air flow mixer is controlled within a range of 5° C. to 30° C.

9. The manufacturing method according to any one of claims 1 to 8, wherein: In the mixing step, the temperature of the air flow mixer is controlled within a range of 5° C. to 19° C.

10. The manufacturing method according to claim 8 or 9, characterized in that: In the mixing step, the temperature of the air flow mixer is controlled by circulating a cooling liquid or a refrigerated air dryer.

11. The manufacturing method according to any one of claims 1 to 10, wherein: The filler is a functional filler or a color powder, The functional filler is an organic filler or an inorganic filler, The organic filler is one or more selected from aramid fiber, polyphenylene ester, polyphenylene sulfide, polyimide, polyetheretherketone, polyphenylene, polyamide and wholly aromatic polyester resin. The inorganic filler is one or more selected from metal powder, graphite, carbon black, coke, carbon powder, carbon fiber, graphene, carbon nanotubes, ceramic powder, talc, mica, aluminum oxide, zinc oxide, tin oxide, titanium oxide, silicon dioxide, calcium carbonate, calcium oxide, magnesium oxide, potassium titanate, glass fiber, glass flakes, glass beads, silicon carbide, calcium fluoride, boron nitride, barium sulfate, molybdenum disulfide and potassium carbonate whiskers.

12. The manufacturing method according to any one of claims 1 to 11, wherein: In the mixing step, the amount of the filler added is 0.1% by weight or more and 60% by weight or less relative to the total amount of the polytetrafluoroethylene resin and the filler added.

13. The manufacturing method according to any one of claims 1 to 12, wherein: In the mixing step, the filler has a particle size of 10 nm to 100 μm.

14. The manufacturing method according to any one of claims 1 to 13, wherein: In the mixing step, a loading coefficient of the polytetrafluoroethylene resin and the filler is 0.2 or more and 0.6 or less.

15. The manufacturing method according to any one of claims 1 to 14, wherein: The polytetrafluoroethylene resin is a polytetrafluoroethylene dispersion resin.

16. A polytetrafluoroethylene composition, characterized in that: It is produced by the production method according to any one of claims 1 to 15.

17. A polytetrafluoroethylene composition, characterized in that: The invention comprises particles of polytetrafluoroethylene resin and a filler covering the surface of the particles, and substantially does not contain an organic solvent. The polytetrafluoroethylene resin is a polytetrafluoroethylene dispersion resin with fiberizing properties. The coverage rate of the surface of the particles covered with the filler is 50% or more and 100% or less.

18. The polytetrafluoroethylene composition according to claim 17, wherein: The average particle size of the polytetrafluoroethylene resin particles is 250 μm or more and 800 μm or less.

19. The polytetrafluoroethylene composition according to claim 17 or 18, wherein: The average particle size of the filler is smaller than the average particle size of the polytetrafluoroethylene resin particles.

20. The polytetrafluoroethylene composition according to any one of claims 17 to 19, wherein: The filler is a functional filler or a color powder, The functional filler is an organic filler or an inorganic filler, The organic filler is one or more selected from aramid fiber, polyphenylene ester, polyphenylene sulfide, polyimide, polyetheretherketone, polyphenylene, polyamide and wholly aromatic polyester resin. The inorganic filler is one or more selected from metal powder, graphite, carbon black, coke, carbon powder, carbon fiber, graphene, carbon nanotubes, ceramic powder, talc, mica, aluminum oxide, zinc oxide, tin oxide, titanium oxide, silicon dioxide, calcium carbonate, calcium oxide, magnesium oxide, potassium titanate, glass fiber, glass flakes, glass beads, silicon carbide, calcium fluoride, boron nitride, barium sulfate, molybdenum disulfide and potassium carbonate whiskers.

21. The polytetrafluoroethylene composition according to any one of claims 17 to 19, wherein: The filler is a functional filler or a color powder, The functional filler is an organic filler or an inorganic filler, The organic filler is one or more selected from polyphenylene ester, polyphenylene sulfide, polyimide, polyetheretherketone, polyphenylene, polyamide and wholly aromatic polyester resin. The inorganic filler is one or more selected from metal powder, graphite, carbon black, coke, carbon powder, graphene, carbon nanotubes, ceramic powder, talc, mica, aluminum oxide, zinc oxide, tin oxide, titanium oxide, silicon dioxide, calcium carbonate, calcium oxide, magnesium oxide, potassium titanate, glass flakes, glass beads, silicon carbide, calcium fluoride, boron nitride, barium sulfate, molybdenum disulfide and potassium carbonate whiskers.

22. The polytetrafluoroethylene composition according to any one of claims 17 to 21, wherein: The content of the filler is 0.1% by weight or more and 60% by weight or less based on the total amount of the polytetrafluoroethylene resin particles and the filler.

23. The polytetrafluoroethylene composition according to any one of claims 17 to 22, wherein: The polytetrafluoroethylene composition is in powder form.

24. The polytetrafluoroethylene composition according to claim 23, wherein: The average particle size of the polytetrafluoroethylene composition is 250 μm or more and 1000 μm or less.

25. A molded article, characterized in that: It is obtained by using the polytetrafluoroethylene composition according to any one of claims 16 to 24.

26. A conductive tube, characterized in that: It is obtained by using the polytetrafluoroethylene composition according to any one of claims 16 to 24.

27. A thermally conductive film, characterized in that: It is obtained by using the polytetrafluoroethylene composition according to any one of claims 16 to 24.

28. A CCL substrate, characterized in that: It is obtained by using the polytetrafluoroethylene composition according to any one of claims 16 to 24.

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