WO2020114419A1 - Preparation method for polytetrafluoroethylene composition, polytetrafluoroethylene composition, forming product, conductive pipe, heat conduction film, and substrate ccl - Google Patents

Abstract

The present invention provides a preparation method for a polytetrafluoroethylene composition, which comprises the step of mixing a polytetrafluoroethylene resin with fillers by an airflow mixer so as to obtain a polytetrafluoroethylene composition comprising the polytetrafluoroethylene resin and the fillers. The present invention also provides a polytetrafluoroethylene composition prepared by the preparation method, a polytetrafluoroethylene composition having the specific physical property, and a forming product, a conductive pipe, a heat conduction film, and a substrate CCL obtained by using the polytetrafluoroethylene composition.

Description

Method for producing polytetrafluoroethylene composition, polytetrafluoroethylene composition, molded product, conductive tube, thermally conductive film, and substrate for CCL Technical field

The present invention relates to a method for producing a polytetrafluoroethylene composition, a polytetrafluoroethylene composition obtained by the production method, a polytetrafluoroethylene composition having specific physical properties, and a polytetrafluoroethylene composition obtained using the polytetrafluoroethylene composition Molded products, conductive tubes, thermal films and substrates for CCL.

Background technique

Polytetrafluoroethylene (PTFE) has excellent properties such as high and low temperature resistance, corrosion resistance, aging resistance, high insulation, and low viscosity, so it is widely used. However, due to its poor dimensional stability, poor thermal conductivity, low hardness, and easy wear, the application of PTFE in the fields of mechanical load bearing, friction and wear, and seal lubrication is limited.

In order to expand the application range of Teflon, it is proposed to improve its performance by blending Teflon with other fillers. As a method of blending polytetrafluoroethylene with other fillers, in the prior art, dry mixing and wet mixing are known. However, in dry mixing (for example, mechanical stirring), PTFE dispersion resin is sensitive to shear force, easy to fibrillate, and the filler is easy to agglomerate, so PTFE and filler can not be uniformly mixed, and coated PTFE particles Incomplete (see figure 1 for particles after compounding). However, wet mixing requires the use of solvents, which is unfriendly to the environment and the process is complicated (see Figure 2 for the particles after compounding).

Patent Document 1 discloses a method for dry mixing a modified polytetrafluoroethylene with an extrusion pressure under RR1600 of less than 25 MPa and a filler in a mechanical stirring device with a stirring blade or the like.

Patent Document 2 discloses a method of mixing polytetrafluoroethylene and a filler by a wet method to obtain a uniform mixed powder, in which the emulsified polymerization is obtained by coagulating from an aqueous dispersion of polytetrafluoroethylene emulsified polymer particles. The polytetrafluoroethylene condensed powder formed by coagulating the particles, and then the condensed powder is mixed with the filler and dry ice, and the mixture is added to an aqueous solution of isopropyl alcohol for granulation.

Patent Literature 1: Japanese Patent Application Publication No. 2018-109149

Patent Literature 2: Japanese Patent Laid-Open No. 2015-151543

Summary of the invention

The present invention has been completed in view of the above-mentioned situation in the prior art, and its object is to provide a method for producing a polytetrafluoroethylene composition capable of uniformly mixing a polytetrafluoroethylene resin and a filler and not easily agglomerating, A polytetrafluoroethylene composition obtained by a method for producing a tetrafluoroethylene composition, a polytetrafluoroethylene composition having specific physical properties, and a molded article obtained using the polytetrafluoroethylene composition, a conductive tube, a thermally conductive film, and Substrate for CCL.

The method for manufacturing the polytetrafluoroethylene composition of the present invention is characterized by including mixing the polytetrafluoroethylene resin and the filler using an air flow mixer, thereby obtaining a polytetrafluoroethylene composition including the polytetrafluoroethylene resin and the filler A step of.

In the manufacturing method of the present invention, the polytetrafluoroethylene resin and the filler are mixed using an air flow mixer. Because there is no mechanical transmission and no shear force during the mixing process with the air flow mixer, it is particularly suitable for PTFE dispersion resin. Compressed air can also disperse and agglomerate the agglomerated or agglomerated materials. Thus, a polytetrafluoroethylene composition in which the polytetrafluoroethylene resin and the filler are uniformly mixed and not easily agglomerated can be obtained by the production method of the present invention.

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

In the production method of the present invention, it is preferable to coat the surface of the particles of polytetrafluoroethylene resin with a filler. Since the air mixer is used for mixing in the present invention, the PTFE resin sensitive to shearing force will not be excessively fibrillated, and the PTFE resin and the filler can be mixed more uniformly, and the filler can be evenly packaged. Cover the surface of the polytetrafluoroethylene resin particles.

In the manufacturing method of the present invention, it is preferable that the airflow mixer is a pulse type airflow mixer. Thereby, the contact probability of PTFE and filler during mixing can be increased, so that the mixing is more uniform.

In the manufacturing method of the present invention, in the mixing step, the pulse interval of the pulsed airflow mixer is preferably adjusted to 5 seconds or more and 30 seconds or less. Thereby, the contact probability of PTFE and filler during mixing can be increased, so that the mixing is more uniform and the production efficiency can be improved at the same time.

In the manufacturing method of the present invention, in the mixing step, the single pulse air flow time of the pulse air flow mixer is preferably set to 0.8 seconds or more and 2 seconds or less. As a result, it is possible to increase the probability that the PTFE at the bottom of the mixer participates in the mixing, and at the same time fully mix the PTFE and the filler.

In the manufacturing method of the present invention, in the mixing step, the number of pulses of the pulsed airflow mixer is preferably set to 5 or more and 40 or less. Thus, the mixing efficiency can be improved while making the mixing more uniform.

In the manufacturing method of the present invention, it is preferable to adjust the intake pressure of the airflow mixer to 0.4 MPa or more and 0.8 MPa or less in the mixing step. Thereby, the mixing space can be enlarged to make the mixing more uniform, and at the same time, the raw material can be prevented from adhering to the top of the mixing chamber and the dust collecting device due to excessive air pressure.

In the manufacturing method of the present invention, in the mixing step, the temperature in the mixing chamber of the airflow mixer is preferably controlled within a range of 5°C or more and 30°C or less. Thereby, the fluidity of the particles can be improved, and the mixing efficiency can be improved.

In the manufacturing method of the present invention, in the mixing step, the temperature in the mixing chamber of the airflow mixer is preferably controlled within a range of 5°C or higher and 19°C or lower. The method of controlling the above temperature is not particularly limited, but, for example, a cooling liquid circulation or a refrigerated air dryer can control the inside of the mixing chamber to a low temperature, thereby achieving a better mixing effect.

In the production method of the present invention, the polytetrafluoroethylene resin is preferably a polytetrafluoroethylene dispersion resin. Generally, the polytetrafluoroethylene dispersion resin is more susceptible to the influence of shearing force, and the manufacturing method of the present invention has no shearing force, so it is more suitable for the mixing of the polytetrafluoroethylene dispersion resin and the filler.

In the manufacturing method of the present invention, the filler is preferably a functional filler or toner, the functional filler is an organic filler or an inorganic filler, and the organic filler is selected from aramid fiber, polyphenylester, polyphenylene sulfide, polyimide , Polyetheretherketone, polyphenylene, polyamide, fully aromatic polyester resin one or more, inorganic filler is selected from metal powder, graphite, carbon black, coke, carbon powder, carbon fiber, graphene, Carbon nanotubes, ceramic powder, talc, mica, alumina, zinc oxide, tin oxide, titanium oxide, silica, calcium carbonate, calcium oxide, magnesium oxide, potassium titanate, glass fiber, glass flakes, glass beads, One or more of silicon carbide, calcium fluoride, boron nitride, barium sulfate, molybdenum disulfide, and potassium carbonate whiskers. Different types of fillers can also be used in combination. In addition, even if they are the same kind of fillers, fillers with different shapes or sizes can be used in combination.

In the production method of the present invention, in the mixing step, the addition amount of the filler is preferably 0.1% by weight or more and 60% by weight or less relative to the total addition amount of the polytetrafluoroethylene resin and the filler. Thereby, the performance of the final molded product can be made more excellent.

In the production method of the present invention, in the mixing step, the particle diameter of the filler is preferably 10 nm or more and 100 μm or less. Thus, more uniform mixing can be achieved.

In the production method of the present invention, in the mixing step, the loading coefficient of the polytetrafluoroethylene resin and the filler is preferably 0.2 or more and 0.6 or less. Thereby, sufficient mixing space can be ensured, the mixing effect can be improved, and at the same time, the spatial density of the PTFE and the filler in the mixing chamber can be ensured, the contact probability can be increased, and the mixing efficiency can be improved.

According to the manufacturing method of the present invention, a polytetrafluoroethylene composition in which a polytetrafluoroethylene resin and a filler are uniformly mixed and not easily agglomerated can be obtained, and using the polytetrafluoroethylene composition, a conductive tube, a thermally conductive film, and a CCL with good performance can be obtained With substrate.

The present invention also relates to a polytetrafluoroethylene composition, characterized in that it contains particles of polytetrafluoroethylene resin and a filler covering the surface of the particles, and substantially does not contain an organic solvent, the polytetrafluoroethylene The resin is a polytetrafluoroethylene dispersion resin having fiberization characteristics, and the coverage rate of the surface of the particles coated with the filler is 50% or more and 100% or less. This polytetrafluoroethylene composition can provide a molded product that can sufficiently exhibit the characteristics derived from the filler. In addition, it is possible to provide a molded article having fewer defects such as scratches, faults, cracks, and holes, and having excellent strength and durability.

In the polytetrafluoroethylene composition, the particles of the polytetrafluoroethylene resin preferably have an average particle size of 250 μm or more and 800 μm or less.

In the polytetrafluoroethylene composition, the average particle diameter of the filler is preferably smaller than the average particle diameter of the particles of the polytetrafluoroethylene resin.

In the polytetrafluoroethylene composition, preferably the filler is a functional filler or toner, the functional filler is an organic filler or an inorganic filler, and the organic filler is selected from aramid fiber, polyphenyl ester, One or more of polyphenylene sulfide, polyimide, polyether ether ketone, polyphenylene, polyamide and wholly aromatic polyester resin, the inorganic filler is selected from metal powder, graphite, carbon black , Coke, carbon powder, carbon fiber, graphene, carbon nanotubes, ceramic powder, talc powder, mica, alumina, zinc oxide, tin oxide, titanium oxide, silica, calcium carbonate, calcium oxide, magnesium oxide, titanic acid One or more of potassium, glass fiber, glass flakes, glass beads, silicon carbide, calcium fluoride, boron nitride, barium sulfate, molybdenum disulfide, and potassium carbonate whiskers.

More preferably, the filler is a functional filler or toner, and the functional filler is an organic filler or an inorganic filler, and the organic filler is selected from polyphenyl ester, polyphenylene sulfide, polyimide, and polyether ether ketone , One or more of polyphenylene, polyamide and wholly aromatic polyester resin, the inorganic filler is selected from metal powder, graphite, carbon black, coke, carbon powder, graphene, carbon nanotubes, ceramics Powder, talc, mica, alumina, zinc oxide, tin oxide, titanium oxide, silicon dioxide, calcium carbonate, calcium oxide, magnesium oxide, potassium titanate, glass flakes, glass beads, silicon carbide, calcium fluoride, nitrogen One or more of boron chloride, barium sulfate, molybdenum disulfide and potassium carbonate whiskers.

In the polytetrafluoroethylene composition, the content of the filler is preferably 0.1% by weight or more and 60% by weight or less relative to the total amount of the particles of the polytetrafluoroethylene resin and the filler.

The polytetrafluoroethylene composition is preferably in powder form.

The polytetrafluoroethylene composition preferably has an average particle size of 250 μm or more and 1000 μm or less.

The present invention also relates to a molded product obtained by using the polytetrafluoroethylene composition, a conductive tube, a thermally conductive film, and a substrate for CCL.

BRIEF DESCRIPTION

FIG. 1 is an optical microscope photograph (magnification: 200 times) of PTFE-carbon black composite particles obtained by mechanical mixing in the prior art (Comparative Example 1).

2 is an optical microscope photograph (magnification: 200 times) of PTFE-carbon black composite particles obtained by wet mixing in the prior art (Comparative Example 2).

3 is an optical microscope photograph of PTFE before mixing used in Examples 1 to 5 (magnification: 200 times).

4 is an optical microscope photograph of PTFE-carbon black composite particles obtained by the manufacturing method of Example 1. (a) is a photograph with a magnification of 200 times, and (b) is a photograph with a magnification of 350 times.

5 is an optical microscope photograph of PTFE-carbon black composite particles obtained by the manufacturing method of Example 2 (magnification: 200 times).

6 is an optical microscope photograph of PTFE-carbon black composite particles obtained by the manufacturing method of Example 3 (magnification: 200 times).

7 is an optical microscope photograph of PTFE-carbon black composite particles obtained by the manufacturing method of Example 4. (a) is a photograph with a magnification of 200 times, and (b) is a photograph with a magnification of 350 times.

8 is an optical microscope photograph of PTFE-carbon black composite particles obtained by the manufacturing method of Example 5 (magnification: 200 times).

9 is an optical microscope photograph of PTFE-carbon fiber composite particles obtained by the manufacturing method of Example 6 (magnification: 200 times).

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

Fig. 11 is an optical microscope photograph of the conductive tube obtained in Comparative Example A'(magnification: 8000 times).

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

13 is an optical microscope photograph of the thermally conductive film obtained in Example B, (a) is a photograph with a magnification of 50 times, and (b) is a photograph with a magnification of 600 times.

Fig. 14 is an optical microscope photograph of the thermally conductive film obtained in Comparative Example B', (a) is a photograph with a magnification of 50 times, and (b) is a photograph with a magnification of 600 times.

15 is a schematic cross-sectional view showing an example of a pulse-type airflow mixer.

16 is an image obtained by binarizing a video microscope photograph of the composition obtained in Example 1. FIG.

17 is an image obtained by binarizing a video microscope photograph of the composition obtained in Comparative Example 1. FIG.

18 is an image obtained by binarizing a video microscope photograph of the composition obtained in Comparative Example 2. FIG.

19 (a) is an electron microscope photograph of the composition obtained in Example 8, (b) is an element map image obtained by element mapping of fluorine using the electron microscope photograph, and (c) is an image of the element map The image obtained by value processing.

20 (a) is an electron microscope photograph of the composition obtained in Comparative Example 3, (b) is an element map image obtained by element mapping of fluorine using the electron microscope photograph, and (c) is an image of the element map The image obtained by value processing.

detailed description

In the manufacturing method of the present invention, the polytetrafluoroethylene (PTFE) resin and the filler are mixed using an air flow mixer, thereby obtaining a uniformly mixed polytetrafluoroethylene composition including the polytetrafluoroethylene resin and the filler.

In the manufacturing method of the present invention, the polytetrafluoroethylene resin and the filler are mixed using an air flow mixer. The principle is that after the compressed air is instantaneously sprayed from the bottom of the mixer, the raw materials in the mixing chamber become boiling and begin to be fully mixed, and the injected air is discharged by the dust collector above. Because there is no mechanical transmission and no shearing force during the mixing process with the air flow mixer, it is particularly suitable for PTFE dispersion materials. Compressed air can also disperse and agglomerate agglomerated or agglomerated materials. Thus, a polytetrafluoroethylene composition in which the polytetrafluoroethylene resin and the filler are uniformly mixed and not easily agglomerated can be obtained by the production method of the present invention.

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

In the production method of the present invention, it is preferable to coat the surface of the particles of polytetrafluoroethylene resin with a filler. Since the air mixer is used for mixing in the present invention, the PTFE resin sensitive to shearing force will not be excessively fibrillated, and the PTFE resin and the filler can be mixed more uniformly, and the filler can be evenly packaged. Cover the surface of the polytetrafluoroethylene resin particles.

The polytetrafluoroethylene (PTFE) resin preferably has fiberization characteristics. The fibrillation characteristics refer to the characteristics of being easily fibrillated to form fibrils.

The presence or absence of fiberization characteristics can be "paste extruded" by a typical method of molding a powder (dispersed resin, ie fine powder) made of an emulsified polymer of tetrafluoroethylene (TFE), that is, a "high molecular weight PTFE powder" To judge. Usually paste-like extrusion is possible due to the fibrillation properties of high molecular weight PTFE powder. When the unfired molded product obtained by paste extrusion does not have substantial strength and elongation, for example, when the elongation is 0% and breakage occurs during stretching, it can be regarded as having no fibrillation .

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

The PTFE resin may be in the form of particles or powder.

In the production method of the present invention, the polytetrafluoroethylene resin may use a PTFE dispersion resin or a PTFE suspension resin, but it is preferred that the polytetrafluoroethylene resin is a polytetrafluoroethylene dispersion resin. Generally, the polytetrafluoroethylene dispersion resin is more susceptible to shearing force and becomes fibrous, and the manufacturing method of the present invention has no shearing force, so it is more suitable for mixing the polytetrafluoroethylene dispersion resin and the filler.

The PTFE dispersion resin is obtained by condensing and drying a dispersion liquid formed by emulsion polymerization. The PTFE dispersion resin in the present invention may be produced according to a known method, or a commercially available polytetrafluoroethylene dispersion resin may be used. Examples of commercially available PTFE dispersion resins include POLYFLON manufactured by Daikin Industries, Ltd., PTFE, F-104, F-208, and F-302.

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

The average particle diameter of the PTFE dispersion resin is preferably 250 μm or more and 800 μm or less, and more preferably 300 μm or more and 600 μm or less.

The standard specific gravity (SSG) of the PTFE dispersion resin is preferably 2.13 or more and 2.28 or less, more preferably 2.14 or more and 2.20 or less; the apparent density of the PTFE dispersion resin is preferably 400 g/L or more and 600 g/L or less; the compression ratio of the PTFE dispersion resin (RR : Reduction) is preferably 20 or more and 3500 or less, and more preferably 100 or more and 3500 or less. The above compression ratio refers to the ratio of the resin cross-sectional area (S1) in the extrusion cylinder to the resin cross-sectional area (S2) at the die.

The average particle diameter of the PTFE suspension resin is preferably 15 μm or more and 200 μm or less; the apparent density of the PTFE suspension resin is preferably 300 g/L or more and 600 g/L or less; the standard specific gravity of the PTFE suspension resin is preferably 2.13 or more and 2.28 or less, and more preferably 2.14 or more. Below 2.20.

The PTFE suspension resin may be PTFE molding powder. The PTFE compression molded powder is a powder obtained by suspension polymerization of TFE. The PTFE compression-molded powder may be obtained by granulating particles obtained by polymerization by a known method.

The average particle size of the PTFE resin is measured according to JIS K6891. The average particle size may be the average particle size of PTFE secondary particles.

The SSG of the PTFE resin was measured by a water displacement method based on ASTM D-792 using a sample formed according to ASTM D 4895-89.

The apparent density of the PTFE resin is measured in accordance with JIS K6891 (in the case of suspended resin, that is, compression-molded powder) or JIS K6892 (in the case of dispersed resin, that is, fine powder).

The PTFE resin preferably has a melting point of 324 to 360°C. The melting point refers to the first melting point. The first melting point corresponds to the maximum value in the heat curve of melting when the temperature is increased at a rate of 10°C/min using a differential scanning calorimeter (DSC) for PTFE without a history of heating to a temperature of 300°C or higher temperature.

The PTFE resin may be a TFE homopolymer composed only of tetrafluoroethylene (TFE) or modified PTFE. The modified PTFE includes a TFE unit and a modified monomer unit based on a modified monomer copolymerizable with TFE.

The modified monomer is not particularly limited as long as it can be copolymerized with TFE, and examples thereof include perfluoroolefins such as hexafluoropropylene (HFP); perhalogenated olefins such as chlorotrifluoroethylene (CTFE); Hydrofluoric olefins such as trifluoroethylene, vinylidene fluoride (VDF), etc.; perfluorovinyl ether; (perfluoroalkyl) ethylene; ethylene; fluorine-containing vinyl ether with nitrile group, etc. In addition, the modified monomer used may be one kind or plural kinds.

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

CF ₂ = CF-ORf ¹ (1)

(In the formula, Rf ¹ represents a perfluorinated organic group.)

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

Examples of the perfluorovinyl ether include perfluoro(alkyl vinyl ether) (PAVE) in which Rf ¹ in the general formula (1) is a perfluoroalkyl group having 1 to 10 carbon atoms. The number of carbon atoms of the perfluoroalkyl group is preferably 1 to 5.

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

As the perfluorovinyl ether, in the above general formula (1), Rf ¹ is a perfluoro(alkoxyalkyl) perfluorovinyl ether having 4 to 9 carbon atoms, and Rf ¹ is as follows The perfluorovinyl ether of the group represented by the formula (2), Rf ¹ is a perfluorovinyl ether of the group represented by the following formula (3), and the like.

(In the formula, m represents 0 or an integer of 1 to 4.)

(In the formula, n represents an integer of 1 to 4.)

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

The fluorine-containing vinyl ether having a nitrile group is more preferably CF ₂ =CFORf ² CN (where Rf ² represents an alkylene group having 2 to 7 carbon atoms in which an oxygen atom may be inserted between two carbon atoms) Fluorine-containing vinyl ether.

The modified monomer in the modified PTFE is preferably at least one selected from HFP, CTFE, VDF, PPVE, PFBE, and ethylene. More preferably, it is at least one monomer selected from HFP and CTFE.

The polymerization unit (modified monomer unit) based on the modified monomer is preferably in the range of 0.00001 to 1.0% by mass. The lower limit of the modified monomer unit is preferably 0.0001% by mass, more preferably 0.0005% by mass, and still more preferably 0.001% by mass. The upper limit of the modified monomer unit is preferably 0.90% by mass, more preferably 0.50% by mass, even more preferably 0.40% by mass, still more preferably 0.30% by mass, particularly more preferably 0.10% by mass, and particularly preferably 0.08% by mass %, particularly preferably 0.05% by mass, particularly preferably 0.01% by mass.

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

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 according to the type of monomer.

In the production method of the present invention, the "filler" is a powdery substance used to improve various physical properties of the molded article, and a functional filler or toner can be used. The functional filler may be various organic fillers or inorganic fillers. Examples of organic fillers include aramid fiber, polyphenylene ester (POB), polyphenylene sulfide (PPS), polyimide (PI), polyether ether ketone (PEEK), polyphenylene, polyamide, and all Engineering plastics such as aromatic polyester resins are preferably polyphenylene ester (POB), polyphenylene sulfide (PPS), polyimide (PI), polyether ether ketone (PEEK), polyphenylene, polyamide, Fully aromatic polyester resin. Examples of inorganic fillers include metal powder, graphite, carbon black, coke, carbon powder, carbon fiber, graphene, carbon nanotubes, ceramic powder, talc, mica, alumina, zinc oxide, tin oxide, titanium oxide, and dioxide. Silicon, calcium carbonate, calcium oxide, magnesium oxide, potassium titanate, glass fiber, glass flakes, glass beads, silicon carbide, calcium fluoride, boron nitride (BN), barium sulfate, molybdenum disulfide, potassium carbonate whiskers, etc. , Preferably metal powder, graphite, carbon black, coke, carbon powder, graphene, carbon nanotubes, ceramic powder, talc powder, mica, alumina, zinc oxide, tin oxide, titanium oxide, silica, calcium carbonate, Calcium oxide, magnesium oxide, potassium titanate, glass flakes, glass beads, silicon carbide, calcium fluoride, boron nitride (BN), barium sulfate, molybdenum disulfide, and potassium carbonate whiskers. Different types of fillers can also be used in combination as needed. In addition, even if they are the same kind of fillers, fillers with different shapes or sizes can be used in combination.

The filler may be an inorganic filler, one or more selected from carbon-based inorganic fillers and ceramic powder, or one or more selected from graphite, carbon black, carbon fiber, and ceramic powder, It may be one or more selected from graphite, carbon black, and ceramic powder.

The filler may be particulate or fibrous, and is preferably particulate.

The particle size of the filler is preferably 10 nm or more and 100 μm or less, and more preferably 10 nm or more and 50 μm or less. Thus, more uniform mixing can be achieved.

The particle size of the filler may be an average particle size, and may be measured by a known measurement method such as an image method, a sieving method, a light scattering method, etc. according to the type of filler.

The average particle diameter of the filler is preferably smaller than the average particle diameter of the particles of the polytetrafluoroethylene resin. Thereby, the surface of the particles of the polytetrafluoroethylene resin can be more uniformly covered with the filler.

The filler preferably has an aspect ratio of 50 or less. Thereby, the surface of the particles of the polytetrafluoroethylene resin can be more uniformly covered with the filler. The aspect ratio is more preferably 30 or less, still more preferably 20 or less, and particularly preferably 10 or less.

The aspect ratio is obtained by observing the filler with a scanning electron microscope (SEM), image processing is performed on 10 or more particles arbitrarily extracted, and is obtained based on the average of the ratio of the major axis to the minor axis.

From the viewpoint of the performance of the final molded product, the addition amount of the filler is preferably 0.1% by weight or more, more preferably 1% by weight or more, and preferably 60% by weight relative to the total addition amount of the polytetrafluoroethylene resin and the filler. % Or less, more preferably 20% by weight or less.

The addition amount is 0.1% by weight or more and 60% by weight or less relative to the total addition amount of the polytetrafluoroethylene resin and the filler, more preferably 1% by weight or more and 60% by weight or less, and still more preferably 1% by weight or more and 20% by weight. %the following.

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

In a preferred embodiment of the production method of the present invention, the loading factor of PTFE and the filler is in the range of 0.2 or more and 0.6 or less. If the loading factor is too large, there is insufficient space for mixing, which affects the mixing effect. If the loading factor is too small, the space density of PTFE and filler in the mixing chamber is small, and the contact probability is low, which affects the mixing efficiency. Among them, the loading factor is the ratio of the filling volume of the material to the volume of the mixing chamber when the mixer can achieve the stirring effect.

In the manufacturing method of the present invention, various airflow mixers such as a pulsed airflow mixer, an airflow agitator, and an airflow pulverizer can be used as the airflow mixer. The airflow mixer has no stirring device and is suitable for PTFE dispersion resin that is relatively sensitive to shear force, which can reduce the phenomenon of agglomeration due to fiberization. Among them, it is preferable to use a pulse type airflow mixer. As a result, the gas enters the mixing chamber in the form of pulses to scatter the materials, especially to increase the contact area between the materials. The high-speed gas can also deagglomerate the agglomerated or agglomerated materials. Therefore, it is beneficial to the mixing.

An example of the pulse type airflow mixer will be described based on the drawings, but the pulse type airflow mixer that can be used in the manufacturing method of the present invention is not limited to this.

15 is a schematic cross-sectional view showing an example of a pulse-type airflow mixer. In the pulse type airflow mixer shown in FIG. 15, a raw material storage tank 4 is provided at the bottom of the mixing tank body 3 that performs airflow mixing. Each raw material such as PTFE resin and filler is introduced from a raw material input port (not shown) provided in the raw material storage tank 4.

The air for air flow mixing is compressed by the air compressor 10 first, then cooled and dried by the cooling dryer 9 and stored in the compressed air storage tank 8. The compressed air is supplied to the raw material storage tank 4 through the nozzle 5 under the pulse condition controlled by the pulse controller 7. Each raw material stored in the raw material storage tank 4 is sprayed by the supplied compressed air, and is mixed in the mixing tank body 3. The temperature in the mixing tank body 3 can be adjusted by the temperature control device 6.

A filter device 2 is provided on the top of the mixing tank body 3, from which 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.

When a pulsed airflow mixer is used, in the mixing step, the pulse interval of the pulsed airflow mixer is preferably adjusted to 5 seconds or more and 30 seconds or less, more preferably 10 seconds or more and 30 seconds or less, and still more preferably 20 seconds or more Less than 30 seconds. If the pulse interval is too small, there may be a filler that has not completely settled, and the next pulse will be entered, which will reduce the probability of contact between the filler and the bottom PTFE, and reduce the effect of fully uniform mixing. If the pulse interval is too large, it may extend the overall mixing time and reduce production efficiency.

When a pulsed airflow mixer is used, the single pulsed airflow 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 pulse air flow mixer is set to 0.8 seconds or more and 2 seconds or less, and more preferably 0.8 seconds or more and 1.5 seconds or less. If the time of single pulse air flow is too short, the probability of PTFE at the bottom of the mixer participating in mixing becomes small; if the time of single pulse air flow is too long, the filler with a smaller apparent density tends to float above all the time, which reduces full and uniform mixing. Effect.

When using a pulsed airflow mixer, the number of pulses can be set according to the loading factor, type of filler, amount of filler added, specific surface area of filler, etc. In the mixing step, the number of pulses of the pulse air mixer is preferably set to 5 times or more and 40 times or less, more preferably 10 times or more and 40 times or less, and still more preferably 15 times or more and 40 times or less. If the number of pulses is too small, the mixing may be insufficient. If the number of pulses is too much, it may cause the mixing period to be extended, reducing the mixing efficiency.

In the manufacturing method of the present invention, in the mixing step, the intake pressure of the airflow mixer is preferably adjusted to 0.4 MPa or more and 0.8 MPa or less, more preferably 0.5 MPa or more and 0.8 MPa or less, and still more preferably 0.6 MPa or more and 0.8 MPa the following. If the intake pressure is less than 0.4 MPa, the height of the raw materials blown up by the airflow is low, and the mixing space is insufficient, resulting in insufficient mixing. If the intake air pressure is greater than 0.8 MPa, the raw materials may directly adhere to the dust filter bag above the mixing chamber and do not participate in the subsequent mixing process.

In the manufacturing method of the present invention, in the mixing step, the temperature of the airflow mixer is preferably controlled within a range of 5°C or more and 30°C or less, preferably 5°C or more and 25°C or less, and more preferably 5°C or more and 19°C Within the following range. As a result, the materials are mixed in a low-temperature environment, the fiberization phenomenon of the polytetrafluoroethylene resin is reduced, the fluidity of the particles can be improved, and the mixing efficiency can be improved.

In the manufacturing method of the present invention, in the mixing step, the temperature of the airflow mixer is preferably controlled by a cooling liquid circulation or a refrigeration air dryer. Thereby, low temperature control can be better achieved, thereby achieving a better mixing effect.

A preferred embodiment of the manufacturing method of the present invention includes the following steps: using a pulse type air flow mixer, according to an appropriate loading factor, put the materials into the air mixing chamber; adjust the intake pressure, pulse interval, single pulse air flow time, Parameters such as the number of pulses; turn on the temperature control system to lower the temperature of the mixing chamber to the temperature required for mixing; start mixing.

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 uniformly coated on the surface of the polytetrafluoroethylene particles, which does not affect the subsequent processing and is conducive to improvement The performance of PTFE.

In the production method of the present invention, it is preferable not to use an organic solvent. In other words, it is preferable that neither the PTFE resin nor the filler is mixed with the organic solvent. The first PTFE composition preferably contains substantially no organic solvent. This can reduce the problems caused by the remaining organic solvent. Specific examples of organic solvents will be described later.

The content of the organic solvent in the first PTFE composition is preferably 500 mass ppb or less with respect to the PTFE composition, more preferably 100 mass ppb or less, further preferably less than 100 mass ppb, even more preferably 10 mass ppb or less, in particular It is preferably 1 mass ppb or less. The lower limit is not particularly limited, and may be less than the detection limit.

The content of the organic solvent can be determined by headspace sampling GC/MS. Specifically, after a 1 g sample was heat-treated at 200°C for 30 minutes by headspace, measurement was performed using Agilent's 5977A (column DB-624). The detection limit of this method is 100 mass ppb.

The present invention also relates to a polytetrafluoroethylene (PTFE) composition (also referred to as a second PTFE composition), which contains particles of polytetrafluoroethylene resin and a filler covering the surface of the particles, and does not substantially Including an organic solvent, the polytetrafluoroethylene resin is a polytetrafluoroethylene dispersion resin having fiberization characteristics, and the coating rate of the surface of the particles coated with the filler is 50% or more and 100% or less.

The second PTFE composition has a coating rate of 50% or more and 100% or less on the surface of the particles coated with the filler, and therefore, a molded article capable of sufficiently exhibiting the characteristics derived from the filler can be supplied. In addition, it is possible to provide a molded article having fewer defects such as scratches, faults, cracks, and holes, and having excellent strength and durability.

The coating rate is preferably 60% or more, more preferably 70% or more, still more preferably 80% or more, still more preferably 90% or more, and particularly preferably 95% or more.

The coverage ratio is calculated by binarizing a 200-fold magnified photograph taken with a video microscope (video microscope VHX-900 manufactured by KEYENCE), and then calculated by the following method.

Coverage rate (%)=S2/(S1+S2)×100

(In the formula, S1 represents the area of the area where the PTFE resin is not covered with the filler, and S2 represents the area of the area where the PTFE resin is covered with the filler.)

The image analysis software used in the binarization process is not particularly limited, and for example, the free software Image J published by the National Institutes of Health NIH can be used.

The second coating rate of the PTFE composition can also be measured using a scanning electron microscope (SEM) and element mapping method.

In some cases, it is difficult to calculate the coverage ratio using an optical microscope photograph due to the mixed state of the PTFE resin and the filler and the color of the filler. For example, in the case where a filler having primary particles smaller than PTFE resin is dispersed and mixed between primary particles of PTFE resin (emulsified particles, particle diameter of 1 m or less), the boundary cannot be recognized in the optical microscope photograph. In such a case, the method of obtaining the coating ratio by the method of using SEM and element mapping is effective.

The coverage ratio based on the above SEM and element mapping can be imaged by elemental mapping of fluorine using SEM (SU8020 Scanning Electron Microscope manufactured by HITACHI), and then the image is binarized and calculated from the video microscope image. The coverage ratio was obtained by the same method.

In the second PTFE composition, the PTFE resin constituting the particles is a PTFE dispersion resin having fiberization characteristics. Thus, the second PTFE composition has excellent fiberization characteristics and can provide a uniform paste extrudate. As the PTFE dispersion resin, the same resin as the PTFE dispersion resin that can be used in the production method of the present invention described above can be used.

The PTFE resin preferably has non-melting secondary processability. The non-melt secondary processability is as described above.

The particles of PTFE resin may be secondary particles of PTFE resin.

The particles of the PTFE resin preferably have an average particle size of 250 μm or more and 800 μm or less, and more preferably 300 μm or more and 600 μm or less.

As the filler in the second PTFE composition, the same filler that can be used in the production method of the present invention described above can be used.

The filler may be particulate or fibrous, and is preferably particulate.

The average particle diameter of the filler is preferably 10 nm or more and 100 μm or less, and more preferably 10 nm or more and 50 μm or less.

The average particle diameter of the filler is preferably smaller than the average particle diameter of the particles of the PTFE resin.

The filler preferably has an aspect ratio of 50 or less, more preferably 30 or less, still more preferably 20 or less, and particularly preferably 10 or less.

In the second PTFE composition, the content of the filler is preferably 0.1% by weight or more, more preferably 1% by weight or more, and more preferably 60% relative to the total addition amount of the particles and filler of the polytetrafluoroethylene resin. The weight% or less, more preferably 20 weight% or less.

The content of the filler can be appropriately set according to the kind of filler. The specific content range of each filler is as described above.

No. 2 The PTFE composition contains substantially no organic solvent. Therefore, it is difficult to cause defects caused by the remaining organic solvent.

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

Specific examples of the organic solvent include alcohols such as methanol, ethanol, and propanol; ketones such as acetone, methyl ethyl ketone (MEK), and methyl isobutyl ketone (MIBK); methyl chloride, and dichloromethane , Chloroform, trichloroethylene and other hydrogen-containing chlorinated hydrocarbons; carbon tetrachloride; 1,1,1,2-tetrafluoroethane, 1,1-difluoroethane, 1,1,1,3,3 -Hydrofluorocarbons such as pentafluoropropane, 1,1,1,2,3,3-hexafluoropropane; 1,1-dichloro-1-fluoroethane, 1,1-dichloro-2, 2,3,3,3-pentafluoropropane, 1,3-dichloro-1,1,2,2,3-pentafluoropropane, 1,1-dichloro-3,3,3-trifluoroethane And other hydrochlorofluorocarbons.

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

The content of the above organic solvent can be measured by GC/MS method of headspace sampling. Specifically, after a 1 g sample was heat-treated at 200°C for 30 minutes by headspace, measurement was performed using Agilent's 5977A (column DB-624). The detection limit of this method is 100 mass ppb.

The second PTFE composition is preferably in powder form.

When the second PTFE composition is in a powder form, the average particle size is preferably 250 μm or more, more preferably 300 μm or more, further preferably 400 μm or more, and preferably 1000 μm or less, more preferably 800 μm or less, and still more preferably 600 μm. the following.

The above average particle diameter is measured according to JIS K6891.

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

The above-mentioned extrusion pressure is measured by the following method. To 60 g of the PTFE composition, 12.3 g of hydrocarbon oil Isopar-G (manufactured by ExxonMobil) as an extrusion aid was added, mixed uniformly in a closed container, and aged at room temperature (25±2° C.) for 1 hour. Then, the above mixture was filled in the cylinder of an extruder based on ASTM D895 (with a compression ratio of 400), and after maintaining at room temperature for 1 minute, a load of 5.7 MPa was applied to the piston inserted into the cylinder immediately. Extruded from the orifice at room temperature at a punching speed of 20 mm/min. The value obtained by dividing the load (N) at the time when the pressure reached the equilibrium state in the extrusion operation by the cross-sectional area of the cylinder was taken as the extrusion pressure (MPa).

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

By molding the first and second PTFE compositions, a molded product can be obtained. The molding method is not particularly limited, and a known method can be used.

The first and second PTFE compositions can be applied to the manufacture of conductive tubes, thermally conductive films, substrates for CCL, battery pole pieces, PTFE pre-coloring materials, and the like. Among them, "CCL" refers to copper-clad (copper-clad laminate).

Specifically, the conductive tube can be obtained by a known method using the first and second polytetrafluoroethylene compositions. For example, the first and second polytetrafluoroethylene compositions may be uniformly mixed with an auxiliary agent, and after aging at a predetermined temperature for a predetermined period of time, the tube may be molded to produce a conductive tube. Compared with the conductive tube obtained by using the polytetrafluoroethylene composition manufactured by mechanical mixing or condensate mixing, the conductive tube obtained by using the first and second polytetrafluoroethylene compositions has a higher yield, and the tube wall Smooth, continuous and uniform conductive layer, excellent conductivity.

In addition, the thermally conductive film can be obtained by a known method using the first and second polytetrafluoroethylene compositions. For example, the first and second polytetrafluoroethylene compositions are uniformly mixed with an auxiliary agent, and after aging at a predetermined temperature for a predetermined period of time, preformed, then extruded into a bar using an extruder, and then passed through a roller By rolling, a thermally conductive film can be produced. Compared with the thermally conductive film obtained by using a polytetrafluoroethylene composition manufactured by mechanical mixing, the thermally conductive film obtained by using the first and second polytetrafluoroethylene compositions has a higher yield rate, a smooth surface, and conductivity and heating power It is more stable and uniform, the mechanical strength and other properties have been significantly improved, and the service life is longer.

Furthermore, the substrate for CCL can be obtained by a well-known method using the first and second polytetrafluoroethylene compositions. For example, the first and second polytetrafluoroethylene compositions are uniformly mixed with an auxiliary agent, and after aging at a predetermined temperature for a predetermined period of time, preformed, then extruded into a bar using an extruder, and then passed through a roller Rolling is performed to form a film, and a plurality of films are thermally laminated, whereby a substrate for CCL can be manufactured. Compared with the substrate for CCL obtained by using a polytetrafluoroethylene composition manufactured by mechanical mixing, the stability of dielectric properties and dimensional stability of the substrate for CCL obtained by using the first and second polytetrafluoroethylene compositions were obtained. Significantly improved.

Conductive tubes can be used for automotive oil pipes, etc., thermal conductive films can be used for automotive heating seats, etc. CCL substrates can be used for printed circuit board industries.

Examples

Example 1

As a mixed raw material, a PTFE resin having a particle diameter of about 550 μm and a carbon black having a particle diameter of 50 nm as a filler are used. The photomicrograph of PTFE before mixing is shown in Figure 3. Put the PTFE resin and carbon black into the mixing chamber of the pulse air mixer, so that the loading factor is 0.2. The added amount of carbon black is 3% by weight of the total added amount of PTFE and carbon black. The mixing chamber is closed, and then the intake pressure is adjusted to 0.4 MPa, the pulse interval is adjusted to 20 seconds, the single pulse air flow time is set to 0.8 seconds, and the pulse number is set to 20 times. Next, turn on the temperature control system (coolant circulation) to lower the temperature of the mixing chamber to 19°C. After the parameter setting is completed, mixing starts. After mixing is complete, turn off the air pump, open the mixing chamber, and discharge.

The optical micrograph of the particles in the mixed composition obtained in Example 1 is shown in FIG. 4, from which it can be clearly seen that the carbon black is uniformly coated on the surface of PTFE after mixing.

Example 2

The load coefficient, intake pressure, pulse interval, single-pulse airflow time, pulse number, and mixing temperature were changed to the values shown in Table 1, and the rest was carried out in the same manner as in Example 1.

The optical micrograph of the particles in the mixed composition obtained in Example 2 is shown in FIG. 5, from which it can be clearly seen that the carbon black is uniformly coated on the surface of PTFE after mixing.

Example 3

The load coefficient, intake pressure, pulse interval, single-pulse airflow time, pulse number, and mixing temperature were changed to the values shown in Table 1, and the rest was carried out in the same manner as in Example 1.

The optical micrograph of the particles in the mixed composition obtained in Example 3 is shown in FIG. 6, from which it can be clearly seen that the carbon black is uniformly coated on the surface of PTFE after mixing.

Example 4

The load coefficient, intake pressure, pulse interval, single-pulse airflow time, pulse number, and mixing temperature were changed to the values shown in Table 1, and the same procedure as in Example 1 was carried out.

The optical micrograph of the particles in the mixed composition obtained in Example 4 is shown in FIG. 7, from which it can be clearly seen that the carbon black is uniformly coated on the surface of PTFE after mixing.

Example 5

The load coefficient, intake pressure, pulse interval, single-pulse airflow time, pulse number, and mixing temperature were changed to the values shown in Table 1, and the rest was carried out in the same manner as in Example 1.

The optical micrograph of the particles in the mixed composition obtained in Example 5 is shown in FIG. 8, from which it can be clearly seen that the carbon black is uniformly coated on the surface of PTFE after mixing.

Table 1

Example 6

As a mixed raw material, a PTFE resin having a particle diameter of about 28 μm and carbon fibers (diameter of 10 μm, average aspect ratio of 10:1) as a filler are used. Put the PTFE resin and carbon fiber into the mixing chamber of the pulse air mixer so that the loading factor is 0.3. The addition amount of carbon fiber is 15% by weight of the total addition amount of PTFE and carbon fiber. The mixing chamber is closed, and then the intake pressure is adjusted to 0.6 MPa, the pulse interval is adjusted to 5 seconds, the single pulse air flow time is set to 1.5 seconds, and the pulse number is set to 10 times. Next, turn on the temperature control system (coolant circulation) to lower the temperature of the mixing chamber to 15°C. After the parameter setting is completed, mixing starts. After mixing is complete, turn off the air pump, open the mixing chamber, and discharge.

The optical micrograph of the particles in the mixed composition obtained in Example 6 is shown in FIG. 9, from which it can be clearly seen that the PTFE resin particles and the carbon fiber are uniformly mixed.

Table 2

Example 7

As a mixed raw material, a PTFE resin having a particle diameter of about 550 μm and a carbon black having a particle diameter of 50 nm as a filler are used. Put the PTFE resin and carbon black into the mixing chamber of the pulse air mixer, so that the loading factor is 0.4. The added amount of carbon black is 3% by weight of the total added amount of PTFE and carbon black. The mixing chamber is closed, and then the intake pressure is adjusted to 0.6 MPa, the pulse interval is adjusted to 25 seconds, the single pulse air flow time is set to 1.2 seconds, and the pulse number is set to 30 times. Next, turn on the temperature control system to lower the temperature of the mixing chamber to 19°C. After the parameter setting is completed, mixing starts. After mixing is complete, turn off the air pump, open the mixing chamber, and discharge. Thus, the PTFE composition of Example 7 can be obtained.

Example 8

As a mixed raw material, PTFE resin having a particle size of about 550 μm, conductive carbon black having a particle size of 36 nm as a filler, and graphite having a particle size of 26 μm as a filler are used. Put the PTFE resin, conductive carbon black and graphite into the mixing chamber of the pulse air mixer, so that the loading factor is 0.5. The added amount of conductive carbon black is 15% by weight of the total added amount of PTFE, conductive carbon black and graphite, and the added amount of graphite is 10% by weight of the total added amount of PTFE, conductive carbon black and graphite. The mixing chamber is closed, and then the intake pressure is adjusted to 0.5 MPa, the pulse interval is adjusted to 30 seconds, the single pulse air flow time is set to 1.2 seconds, and the pulse number is set to 30 times. Next, turn on the temperature control system (coolant circulation) to lower the temperature of the mixing chamber to 19°C. After the parameter setting is completed, mixing starts. After mixing is complete, turn off the air pump, open the mixing chamber, and discharge. Thus, the PTFE composition of Example 8 can be obtained.

Example 9

As a mixed raw material, a PTFE resin having a particle diameter of about 550 μm and a ceramic powder having a particle diameter of 20 nm as a filler are used. Put the PTFE resin and ceramic powder into the mixing chamber of the pulse air mixer, so that the loading factor is 0.35. The added amount of ceramic powder is 50% by weight of the total added amount of PTFE and ceramic powder. The mixing chamber is closed, and then the intake pressure is adjusted to 0.7 MPa, the pulse interval is adjusted to 20 seconds, the single pulse air flow time is set to 1.5 seconds, and the pulse number is set to 30 times. Next, turn on the temperature control system (coolant circulation) to lower the temperature of the mixing chamber to 19°C. After the parameter setting is completed, mixing starts. After mixing is complete, turn off the air pump, open the mixing chamber, and discharge. Thus, the PTFE composition of Example 9 can be obtained.

table 3

Comparative example 1 (mechanical mixing)

Using the same PTFE resin and filler (carbon black) as in Example 1, add the PTFE resin and carbon black weighed at a mass ratio of 3% to the mixing chamber of the mechanical mixer with a stirring structure to ensure the volume of the added material Not more than 1/3 of the volume of the mixing cabin. Adjust the angle and height of the spoiler and close the mixing cabin. Adjust the rotation speed to 1200r/min, the mixing time is 120 seconds, and mix. After mixing, the material is discharged.

The optical micrograph of the particles in the mixed composition obtained in Comparative Example 1 is shown in FIG. 1, from which it can be clearly seen that the PTFE resin is fibrillated.

Comparative example 2 (condensation mixing)

Using the same PTFE resin and filler (carbon black) as in Example 1, add the carbon black weighed at a mass ratio of 3% to the mixture of alcohol and water (volume ratio of alcohol to water 1:2.5), ultrasonic Disperse to obtain a pre-dispersed liquid of carbon black. The carbon black pre-dispersion liquid was mechanically stirred at a low speed, and two minutes later, the PTFE dispersion stock solution was gently added. After the stirring continued for 3 minutes, the rotation speed was increased, and a small amount of flocculant was added at the same time, a large amount of the mixture precipitated, and then the stirring was continued for 10 minutes, and the stirring was stopped. Filter to remove most of the solvent. The PTFE composition of Comparative Example 2 was obtained by drying at 100° C. or lower for 24 hours or more.

The optical microscope photograph of the particles in the mixed composition obtained in Comparative Example 2 is shown in FIG. 2, from which it can be clearly seen that most of the carbon black is wrapped inside the PTFE resin.

The PTFE compositions prepared in the above Examples 7 to 9 were used to prepare the products described in the following Examples A to C, respectively, and the properties of these products were evaluated according to the following methods.

<performance evaluation>

1. Current value

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

The higher the current value, the lower the resistance of the material and the higher the conductivity.

2. Volume resistivity

Volume resistivity is the impedance of a unit volume of material to current.

In the present invention, the volume resistivity of the obtained thermally conductive film is measured according to the test standard GB/T1410-2006. Specifically, the thermally conductive film was made into a test piece of 70 mm×50 mm×0.13 mm (a*b*h). Next, set the test piece on the test stand, adjust the nut tightly, apply 500V voltage, and use the ST2258C digital four-probe tester to measure the resistance value R _{X of} the test piece. Then, according to the formula ρ _V =R _X *a*b/h, the volume resistivity is calculated, and its unit is Ω·cm.

The higher the volume resistivity, the higher the insulation of the material and thus the lower the conductivity. In the present invention, the volume resistivity is preferably less than 0.8 Ω·cm.

3. Tensile strength TS and elongation at break EL

Tensile strength indicates the ability of a material to resist permanent deformation and damage under the action of external forces. The elongation at break represents the ratio of the displacement value of the sample at the time of breaking to the original length.

In the present invention, the tensile strength and elongation at break of the obtained thermally conductive film are measured in accordance with the test standard ASTM D4894 using an Instron 3366 universal tensile testing machine. Specifically, after the heat conductive film is formed into a dumbbell-shaped test piece, the gauge length L0 is set, and the width a and the thickness b of the test piece are measured. Next, place it on the fixture. After the displacement and stress are cleared, the test is started, and the stretching is performed at a stretching speed of 50 mm/min until breakage occurs. Record the stress F and length L1 at break. 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 were calculated.

The higher the tensile strength, the higher the mechanical strength of the material. The higher the elongation at break, the higher the toughness of the material. In the present invention, it is preferable that the tensile strength is greater than 20 MPa and the elongation at break is greater than 200%.

4. Temperature drift

Temperature drift means the relative average rate of change of the dielectric constant when the temperature increases by 1°C within a certain temperature range (-50～150°C).

In the present invention, according to the test standard IPC-TM-650 2.5.5.5, using an Agilent N5234A tester, the temperature drift of the obtained substrate for CCL is measured. Specifically, the CCL substrate is made into a test piece of 30 mm×70 mm×0.8 mm, the test piece is fixed to a jig, and its dielectric constant in the z-axis direction at normal temperature and 10 GHz is measured, and the test is repeated 4 to 4 5 times, take the average. Next, the test was repeated at different temperatures in the temperature range of -50 to 150°C to prepare a graph of the change in dielectric constant with temperature. The slope was obtained from the obtained graph, and the slope was used as the temperature drift.

The lower the absolute value of 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.

5. Coefficient of thermal expansion

The coefficient of thermal expansion represents the relative change in the size of an object every time the temperature increases by 1°C.

In the present invention, the thermal expansion coefficient of the substrate for CCL is measured in accordance with 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 the TMA static thermomechanical analysis method.

The lower the thermal expansion coefficient, the smaller the dimensional change of the material with increasing temperature, and the higher the dimensional stability of the product. In the present invention, the thermal expansion coefficient is preferably (x, y, z) <(50, 50, 100). Among them, "(x, y, z)" means that for every 1°C increase in temperature, x, ppm, y, and z ppm increase in the three directions of length, width, and thickness, respectively. The following is the same.

Example A

Using the PTFE composition obtained in Example 7, it was uniformly mixed with the auxiliary oil Isopar-G ^*1 , and after aging at 40°C for 24 hours, the tube was molded. Thus, the conductive tube of Example A was obtained.

The PTFE pipe extrusion equipment used in the molding is manufactured by Japan Tanabata. The diameter of the steel cylinder/mandrel is 100/20mm, the diameter of the die/needle film is 10.5/8.3mm, and the RR ratio is 232. Extrusion during molding The pressure is 19 MPa.

Using an optical microscope, the surface of the conductive tube obtained in Example A was observed 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. It can be clearly seen from FIG. 10 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 and faults.

In addition, the current value of the conductive tube obtained in Example A was measured. Table 4 shows the obtained results.

*1: Made by ExxonMobil, the specific gravity is 0.748, the flash point is 440°C, and the boiling point is 167-176°C.

Comparative Example A’

Except for using the PTFE composition obtained in Comparative Example 1, the same procedure as in Example A was carried out to obtain a conductive tube of Comparative Example A'.

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. 11. It can be clearly seen from Fig. 11 that PTFE fiberization has occurred and there are small cracks, which will affect the service life and compressive strength of the pipe.

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.

Comparative Example A"

Except for using the PTFE composition obtained in Comparative Example 2, the same procedure as in Example A was carried out to obtain a conductive tube of Comparative Example A".

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. 12. It can be clearly seen from FIG. 12 that there are a large number of white clumps and the surface Very uneven, this is because carbon black is wrapped inside PTFE resin.

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.

Table 4

A	Measured current value
Example A	＞400mA
Comparative Example A’	200～300mA
Comparative Example A"	No current

From the results in Table 4, it can be seen that the current value of the conductive tube made using the polytetrafluoroethylene composition manufactured by the manufacturing method of the present invention is high and uniformly stable, which indicates that its conductivity is better. In contrast, the current value of the conductive tube obtained by using the polytetrafluoroethylene composition manufactured by the mechanical mixing method is low, which means that the conductive tube obtained in Comparative Example A'has high resistance and poor conductivity. Further, the tube made using the polytetrafluoroethylene composition manufactured by the coagulation mixing method did not detect the current value, which indicates that the tube has no conductivity and cannot be used as a conductive tube.

Since the product prepared using the polytetrafluoroethylene composition manufactured by the condensate mixing method does not have electrical conductivity, the product does not have thermal conductivity. Therefore, in the following test, the polytetrafluoroethylene composition produced by the coagulation mixing method was not used to produce a thermally conductive film.

Example B

Using the PTFE composition obtained in Example 8, it was uniformly mixed with the auxiliary oil Isopar-M ^*2 , and after aging at 40°C for 24 hours, pre-molding was carried out at a pressure of 3 MPa for 20 minutes. Then, an extruder was used to extrude a rod with a diameter of 11 mm at an extrusion pressure of about 5.2 MPa. Next, a 0.13 mm film was formed by roll rolling, and dried and sintered to obtain a PTFE thermal conductive film.

Using an optical microscope, the surface of the thermally conductive film obtained in Example B was observed at a magnification of 50 times and 600 times, respectively, to obtain an optical microscope photograph of the surface of the thermally conductive film. The obtained photograph is shown in Fig. 13. It can be clearly seen from FIG. 13 that the surface of the thermal conductive film is smooth and uniform, and there are no holes.

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 shown in Table 5 together.

*2: Made by ExxonMobil, the specific gravity is 0.79, the flash point is 92°C, and the boiling point is 225-254°C.

Comparative Example B’

Except for using the PTFE composition obtained in Comparative Example 1, the same procedure as in Example B was carried out to obtain a thermally conductive film of Comparative Example B'.

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. 14. It can be clearly seen from FIG. 14 that there is a partial fibrosis phenomenon, and there are holes on the surface of the film, which will result in insufficient mechanical strength, uneven overall heating, the risk of local overheating, and a low service life.

In addition, the volume resistivity, tensile strength, and elongation at break of the thermally conductive film obtained in Comparative Example B'were measured. Table 5 also shows the obtained results.

table 5

From the results in Table 5, it can be seen that the thermally conductive film prepared using the polytetrafluoroethylene composition manufactured by the manufacturing method of the present invention has greater mechanical strength, higher toughness, and thus longer service life, and in addition, lower volume resistivity , The heating efficiency is higher and the heating is more uniform. In contrast, a thermally conductive film made using a polytetrafluoroethylene composition manufactured by a mechanical mixing method has poor mechanical strength and high volume resistivity, resulting in low heat generation efficiency and short service life.

Example C

Using the PTFE composition obtained in Example 9, it was uniformly mixed with the auxiliary oil Isopar-M ^*2 , and after aging at 40°C for 24 hours, pre-molding was carried out at a pressure of 3 MPa for 20 minutes. Then, an extruder was used to extrude rods with a diameter of 16 mm at an extrusion pressure of about 4 MPa. Next, a 0.165 mm film was formed by roll pressing, and dried and sintered to form a PTFE film. Eight PTFE films of the same size obtained were thermally laminated to obtain a 0.8 mm substrate for CCL.

Then, the temperature drift and thermal expansion coefficient of the substrate for CCL obtained in Example C were measured. Table 6 also shows the obtained results.

Comparative Example C’

Except for using the PTFE composition obtained in Comparative Example 1, the same procedure as in Example C was carried out to obtain a substrate for CCL of Comparative Example C'. Then, the temperature drift and thermal expansion coefficient of the substrate for CCL obtained in Comparative Example C'were measured. Table 6 also shows the obtained results.

Table 6

From the results in Table 6, it can be seen that the substrate for CCL prepared using the polytetrafluoroethylene composition manufactured by the manufacturing method of the present invention has a lower temperature drift and a lower coefficient of thermal expansion, and therefore has a more stable Dielectric properties and dimensional stability are conducive to improving the efficiency of signal transmission, reducing losses, and have a better composite effect with copper foil.

Experiment 1

The PTFE composition obtained in Example 1, Comparative Example 1 and Comparative Example 2 and the PTFE resin (raw material of PTFE composition) used in Example 1 and Comparative Example 1 were subjected to fiberization by a paste extrusion test Evaluation of characteristics.

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

Next, using an extruder based on ASTM D895, using a die with a compression ratio of 400, a paste extrusion test was performed. That is, the cylinder of the extruder was filled with the above mixture, and after maintaining at room temperature for 1 minute, a load of 5.7 MPa was immediately applied to the piston inserted in the cylinder, and immediately extruded from the orifice at a punching speed of 20 mm/min at room temperature . The state of the extrudate (called bead) extruded from the orifice was observed, and the extrusion pressure was measured.

In addition, the value obtained by dividing the load (N) at the time when the pressure reached the equilibrium state during the extrusion operation by the cylinder cross-sectional area was taken as the extrusion pressure (MPa).

For the PTFE compositions obtained in Example 1 and Comparative Example 2, uniform paste extrudates were obtained. The extrusion pressure of the PTFE composition obtained in Example 1 and Comparative Example 2 was only found to be increased by only 20% compared to the extrusion pressure (33 MPa) of the raw material PTFE resin.

On the other hand, the extrudate of the PTFE composition obtained in Comparative Example 1 was uneven, cracked partially, and twisted. The tensile test of the extrudate (unfired) was conducted, and as a result, the non-uniform portion had no substantial strength and elongation, and the extrudate broke.

In addition, the PTFE composition obtained in Comparative Example 1 exhibited a pressure increase from the initial stage of extrusion compared to the extrusion pressure of the PTFE resin as a raw material, the extrusion pressure was unstable, and did not reach an equilibrium state. Therefore, the extrusion pressure cannot be calculated.

According to the results of the paste extrusion test, the fiberization characteristics of the PTFE compositions obtained in Example 1 (air flow mixing) and Comparative Example 2 (condensation mixing) are equivalent to those of the raw material PTFE resin. Excellent results.

On the other hand, the fiberization characteristics of the PTFE composition obtained in Comparative Example 1 (mechanical mixing) became significantly poorer.

Experiment 2

For the PTFE compositions obtained in Example 1, Comparative Example 1 and Comparative Example 2, the organic solvent contained in the PTFE composition was analyzed by headspace sampling GC/MS method.

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

As a result of the analysis, it was found 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 from the PTFE composition obtained in Comparative Example 2.

Comparative Example 3

According to Examples 4 and 5 described in Japanese Patent Laid-Open No. 8-253600, a PTFE composition composed of PTFE resin, carbon black, and graphite was obtained.

As the PTFE resin, an aqueous dispersion of PTFE resin used in Example 8 was used, and the same carbon black and graphite as in Example 8 were used as the conductive carbon black and graphite. The mixing ratio of conductive carbon black and graphite is the same as in Example 8, the amount of conductive carbon black added to PTFE, the total amount of carbon black and graphite is set to 15% by weight, and the amount of graphite added to PTFE The total amount of carbon black and graphite added is set to 10% by weight.

In addition, as the water-insoluble organic solvent, 1,1-dichloro-1-fluoroethane is used in the same manner as Japanese Patent Laid-Open No. 8-253600.

Experiment 3

For the PTFE compositions obtained in Example 8 and Comparative Example 3, the organic solvent contained in the PTFE composition was analyzed by headspace sampling GC/MS.

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

As a result of the analysis, it was found 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 (1.2 mass ppm) was detected from the PTFE composition obtained in Comparative Example 3.

Experiment 4

The coverage of the PTFE composition obtained in each example and comparative example was calculated. Table 7 shows the results.

Table 7

16, 17 and 18 show images obtained by binarizing video micrographs of the compositions obtained in Example 1, Comparative Example 1 and Comparative Example 2.

19(a), (b), and (c) show an electron microscope photograph of the composition obtained in Example 8, an element map image obtained by element mapping of fluorine using the electron microscope photograph, and the element The image obtained by binarizing the map image.

20 (a), (b), and (c) show an electron microscope photograph of the composition obtained in Comparative Example 3, an element map image obtained by element mapping of fluorine using the electron microscope photograph, and the element The image obtained by binarizing the map image.

Claims (28)

1. A method for manufacturing a polytetrafluoroethylene composition, characterized in that:

   It includes the steps of mixing the polytetrafluoroethylene resin and the filler using an air flow mixer, thereby obtaining a polytetrafluoroethylene composition including the polytetrafluoroethylene resin and the filler.
2. The manufacturing method according to claim 1, wherein:

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

   The airflow mixer is a pulsed airflow mixer.
4. The manufacturing method according to claim 3, wherein:

   In the mixing step, the pulse interval of the pulsed air flow mixer is adjusted to 5 seconds or more and 30 seconds or less.
5. The manufacturing method according to claim 3 or 4, wherein:

   In the mixing step, the single pulse air flow time of the pulse air flow mixer is set to 0.8 seconds or more and 2 seconds or less.
6. The manufacturing method according to any one of claims 3 to 5, wherein:

   In the mixing step, the number of pulses of the pulsed air flow mixer is set to 5 times or more and 40 times or less.
7. The manufacturing method according to any one of claims 1 to 6, wherein:

   In the mixing step, the intake pressure of the airflow mixer is adjusted to 0.4 MPa or more and 0.8 MPa or less.
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 or higher and 30°C or lower.
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 or higher and 19°C or lower.
10. The manufacturing method according to claim 8 or 9, wherein:

    In the mixing step, the temperature of the airflow mixer is controlled by a cooling liquid circulation or a refrigeration air dryer.
11. The manufacturing method according to any one of claims 1 to 10, characterized in that:

    The filler is a functional filler or toner,

    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, polyether ether ketone, polyphenylene, polyamide and wholly aromatic polyester resin ,

    The inorganic filler is selected from metal powder, graphite, carbon black, coke, carbon powder, carbon fiber, graphene, carbon nanotube, ceramic powder, talc powder, mica, alumina, zinc oxide, tin oxide, titanium oxide, titanium dioxide, One of silicon oxide, 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 One or more.
12. The manufacturing method according to any one of claims 1 to 11, wherein:

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

    In the mixing step, the particle size of the filler is 10 nm or more and 100 μm or less.
14. The manufacturing method according to any one of claims 1 to 13, wherein:

    In the mixing step, the 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 by:

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

    Particles containing polytetrafluoroethylene resin and fillers covering the surface of the particles, and substantially no organic solvent,

    The polytetrafluoroethylene resin is a polytetrafluoroethylene dispersion resin having fiberization characteristics,

    The coating rate of the surface of the particles coated with the filler is 50% or more and 100% or less.
18. The polytetrafluoroethylene composition according to claim 17, characterized in that:

    The average particle diameter of the particles of the polytetrafluoroethylene resin is 250 μm or more and 800 μm or less.
19. The polytetrafluoroethylene composition according to claim 17 or 18, characterized in that:

    The average particle diameter of the filler is smaller than the average particle diameter of the particles of the polytetrafluoroethylene resin.
20. The polytetrafluoroethylene composition according to any one of claims 17 to 19, characterized in that:

    The filler is a functional filler or toner,

    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, polyether ether ketone, polyphenylene, polyamide and wholly aromatic polyester resin ,

    The inorganic filler is selected from metal powder, graphite, carbon black, coke, carbon powder, carbon fiber, graphene, carbon nanotube, ceramic powder, talc powder, mica, alumina, zinc oxide, tin oxide, titanium oxide, titanium dioxide, One of silicon oxide, 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 One or more.
21. The polytetrafluoroethylene composition according to any one of claims 17 to 19, characterized in that:

    The filler is a functional filler or toner,

    The functional filler is an organic filler or an inorganic filler,

    The organic filler is one or more selected from polyphenyl ester, polyphenylene sulfide, polyimide, polyether ether ketone, polyphenylene, polyamide and wholly aromatic polyester resin,

    The inorganic filler is selected from metal powder, graphite, carbon black, coke, carbon powder, graphene, carbon nanotubes, ceramic powder, talc powder, mica, alumina, zinc oxide, tin oxide, titanium oxide, silica , 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, characterized in that:

    The content of the filler is 0.1% by weight or more and 60% by weight or less relative to the total amount of the particles of the polytetrafluoroethylene resin and the filler.
23. The polytetrafluoroethylene composition according to any one of claims 17 to 22, characterized in that:

    The polytetrafluoroethylene composition is in powder form.
24. The polytetrafluoroethylene composition according to claim 23, characterized in that:

    The average particle diameter of the polytetrafluoroethylene composition is 250 μm or more and 1000 μm or less.
25. A molded product characterized by:

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

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

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

    It is obtained using the polytetrafluoroethylene composition according to any one of claims 16 to 24.

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