Modified polytetrafluoroethylene resin powder and molded article

Abstract

The present invention relates to a powder containing a modified polytetrafluoroethylene resin, the powder having a median diameter (D50) of 6000 [mu] m or less and a storage modulus (G ') of 1.0 * 105 Pa or less at a temperature of 333 DEG C as measured under the conditions of a frequency of 1 Hz, a strain of 0.3%, and a temperature increase rate of 3 DEG C / min.

Description

Technical Field

[0001] The invention relates to a modified polytetrafluoroethylene resin powder and a molded body. Background Art

[0002] Fluororesin is a synthetic resin with excellent heat resistance, electrical insulation and weather resistance, and is widely used in industrial fields such as chemical materials, electrical and electronic components, semiconductors and automobiles.

[0003] For example, polytetrafluoroethylene (hereinafter, sometimes referred to as PTFE) or the like has a very high melt viscosity and is therefore difficult to melt-mold by extrusion molding, etc., unlike conventional thermoplastic resins.

[0004] As a molding method for such a resin that is difficult to melt-mold, a raw material powder is compression-molded and fired, and then cut to give the obtained molded body a predetermined shape. However, a large amount of chips are generated in the cutting process.

[0005] Therefore, from the perspective of reducing environmental load (saving resources, saving energy, and reducing greenhouse gas emissions) and reducing raw material costs, it is necessary to effectively utilize waste materials such as chips.

[0006] However, it is known that when PTFE scrap that has been subjected to a primary heat treatment (calcination) is used as a raw material powder and then molded and calcined, the mechanical strength of the obtained molded body is significantly reduced.

[0007] Patent Documents 1 and 2 disclose that a molded article made of a mixture of a heated PTFE resin that has been subjected to a single heating treatment (calcination) and an unheated PTFE resin that has never been subjected to a single heating treatment exhibits a mechanical strength close to that of a molded article made of the unheated PTFE resin.

[0008] Patent document 3 discloses that by using as a raw material a mixture of a crushed product of a PTFE resin that has been subjected to a single heat treatment (calcination) and a PTFE resin obtained by emulsion polymerization that has never been subjected to a single heat treatment (calcination) (so-called virgin resin), the strength of a calcined body of the mixture is improved.

[0009] Patent Document 4 discloses obtaining a blank using only a PTFE processing residue that has been subjected to a single heating treatment.

[0010] Prior art literature

[0011] Patent Literature

[0012] Patent Document 1: Japanese Patent No. 4714310

[0013] Patent Document 2: Japanese Patent Application Publication No. 2015-108126

[0014] Patent Document 3: Japanese Patent No. 6612001

[0015] Patent Document 4: Japanese Patent Application Publication No. 2004-291462 Summary of the invention

[0016] However, in the techniques of Patent Documents 1 to 3, since it is necessary to mix an unheated fluororesin with a heated fluororesin, sufficient effects in reducing environmental load and reducing raw material costs are not necessarily achieved.

[0017] Furthermore, the blank produced using only the processing residue of PTFE that has been subjected to a heating step as described in Patent Document 4 does not necessarily have sufficient strength.

[0018] An object of the present invention is to provide a powder containing a modified polytetrafluoroethylene resin having a specific thermal behavior.

[0019] Another object of the present invention is to provide a molded product containing the modified polytetrafluoroethylene resin and having sufficient strength.

[0020] According to the present invention, it is possible to provide the following powder containing a modified polytetrafluoroethylene resin.

[0021] <1> A powder containing modified polytetrafluoroethylene resin, wherein the median particle size D of the powder is 50 The storage modulus G' of the powder at 333°C measured under the conditions of frequency 1 Hz, strain 0.3%, and heating rate 3°C / min is 1.0×10 5 Below Pa.

[0022] <2> According to the above <1> The powder containing modified polytetrafluoroethylene resin, wherein basically no ball blocks are observed in the image of the sintered product obtained by sintering the powder at a temperature of 365°C for 4 and a half hours using a scanning electron microscope at a magnification of 10,000 times.

[0023] <3> According to the above <1> or <2> The powder containing modified polytetrafluoroethylene resin, wherein the melting point of the modified polytetrafluoroethylene resin is below 333°C.

[0024] <4> A molded body, wherein the molded body is formed by 50 The storage modulus G' at 333°C measured under the conditions of frequency 1 Hz, strain 0.3%, and heating rate 3°C / min is 1.0×10 5 It is obtained by compression molding and sintering a powder containing a modified polytetrafluoroethylene resin with a density of Pa or less.

[0025] <5> .according to <4> The molded body has a tensile strength of 13 MPa or more.

[0026] <6> .according to <4> or <5> The molded body has a tensile elongation of 100% or more.

[0027] <7> .according to <4> ~ <6> The molded article according to any one of the preceding claims, wherein substantially no knurled block is observed in an image of the surface or cross section of the molded article taken at a magnification of 20,000 times using a scanning electron microscope.

[0028] <8> .according to <4> ~ <7> The molded article according to any one of the preceding claims, wherein a continuously extending band-like structure is observed in an image obtained by photographing a cross section of the molded article at a magnification of 45,000 times using a scanning electron microscope.

[0029] According to the present invention, a powder containing a modified polytetrafluoroethylene resin having a specific thermal behavior can be provided.

[0030] The present invention can also provide a molded product containing the modified polytetrafluoroethylene resin and having sufficient strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 These are the measurement results of the storage modulus G′ of unheated modified PTFE resin powder A, unheated homopolymer PTFE resin powder B, heated modified PTFE resin powder A-1 of a certain embodiment of the powder of a certain embodiment of the present invention, and heated homopolymer PTFE resin powder B-1.

[0032] Figure 2-1 These are FE-SEM images of unheated modified PTFE resin powder A before and after sintering.

[0033] Figure 2-2 These are FE-SEM images of unheated homopolymer PTFE resin powder B before and after sintering.

[0034] Figure 2-3 FE-SEM images of unheated homopolymer PTFE resin powder C before and after sintering.

[0035] Figure 2-4 These are FE-SEM images of unheated homopolymer PTFE resin powder D before and after sintering.

[0036] Figure 2-5 These are FE-SEM images of the heated modified PTFE resin powder A-1 before and after sintering, which is one embodiment of the powder according to one embodiment of the present invention.

[0037] Figure 2-6 These are FE-SEM images of the heated homopolymer PTFE resin powder B-1 before and after sintering.

[0038] Figure 3 (A) is a schematic diagram for explaining the method for producing a molded body of the present invention, and (B) is a diagram for explaining the behavior of a powder in the process for producing a molded body of the present invention.

[0039] Figure 4 This is a graph showing the tensile strength of each molded body using unheated homo-PTFE resin powder B, heated homo-PTFE resin powder B-1, unheated modified PTFE resin powder A, and heated modified PTFE resin powder A-1 which is a certain embodiment of the powder according to a certain embodiment of the present invention.

[0040] Figure 5 This is a graph showing the tensile elongation of each molded body using unheated homo-PTFE resin powder B, heated homo-PTFE resin powder B-1, unheated modified PTFE resin powder A, and heated modified PTFE resin powder A-1 which is a certain embodiment of the powder according to a certain embodiment of the present invention.

[0041] Figure 6-1 This is a FE-SEM (field emission scanning electron microscope) image of the surface of the molded body of Example 2.

[0042] Figure 6-2 This is a FE-SEM (field emission scanning electron microscope) image of the surface of the molded body of Comparative Example 6.

[0043] Figure 7-1 This is a FE-SEM (field emission scanning electron microscope) image of a cross section of the molded body of Example 2.

[0044] Figure 7-2 This is a FE-SEM (field emission scanning electron microscope) image of a cross section of the molded body of Comparative Example 6. DETAILED DESCRIPTION

[0045] The fluororesin, the molded article and the method for producing the same according to the present invention are described below.

[0046] In this specification, "x to y" means a numerical range of "x or more and y or less". Regarding technical matters, when there are multiple lower limits such as "x or more" or multiple upper limits such as "y or less", these upper limits and lower limits can be arbitrarily selected and combined.

[0047] [Powder containing modified polytetrafluoroethylene resin]

[0048] The powder involved in one embodiment of the present invention has a median particle size D 50 The storage modulus G' at 333°C measured under the conditions of frequency 1 Hz, strain 0.3%, and heating rate 3°C / min is 1.0×10 5 Powder containing modified polytetrafluoroethylene resin with a molecular weight of less than Pa.

[0049] (Modified polytetrafluoroethylene resin)

[0050] In the modified polytetrafluoroethylene resin (hereinafter referred to as "modified PTFE resin") used in the present embodiment, there is no particular limitation on the monomer (referred to as "modified monomer") used to modify the polytetrafluoroethylene resin (hereinafter referred to as "PTFE resin") as long as the monomer can be polymerized with PTFE, and for example, perfluoroolefins such as hexafluoropropylene (HFP); hydrogen-containing fluoroolefins such as trifluoroethylene and vinylidene fluoride (VDF); perhalogenated olefins such as chlorotrifluoroethylene; perfluorovinyl ether; perfluoroallyl ether; (perfluoroalkyl)ethylene, ethylene, etc. In addition, the modified monomers used may be one or more.

[0051] The perfluorovinyl ether is not particularly limited, and examples thereof include perfluorounsaturated compounds represented by the following formula (1).

[0052] CF2=CF-OR f (1)

[0053] In the formula, R f In the present 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 contain ether oxygen.

[0054] Examples of the perfluorovinyl ether include: f Perfluoro(alkyl vinyl ether) (PAVE) of a perfluoroalkyl group having 1 to 10 carbon atoms. The perfluoroalkyl group preferably has 1 to 5 carbon atoms.

[0055] Examples of the perfluoroalkyl group in PAVE include a perfluoromethyl group, a perfluoroethyl group, a perfluoropropyl group, a perfluorobutyl group, a perfluoropentyl group, and a perfluorohexyl group.

[0056] Examples of the perfluorovinyl ether include: f is an ether of a perfluoro(alkoxyalkyl) group having 4 to 9 carbon atoms, R f The chemical formula is:

[0057]

[0058] (wherein m represents 0 or an integer of 1 to 4.) ether of the group represented by f It is the following formula (2):

[0059]

[0060] (In the formula (2), n is an integer of 1 to 4.) ethers of the groups represented by

[0061] The (perfluoroalkyl)ethylene (PFAE) is not particularly limited, and examples thereof include (perfluorobutyl)ethylene (PFBE) and (perfluorohexyl)ethylene.

[0062] Examples of the perfluoroallyl ether include fluorine-containing monomers represented by the following formula (3).

[0063] CF2=CF-CF2-OR f1 (3)

[0064] (Where R f1 represents a perfluorinated organic group. )

[0065] The above R f1 It is preferably a perfluoroalkyl group having 1 to 10 carbon atoms or a perfluoroalkoxyalkyl group having 1 to 10 carbon atoms. As the perfluoroallyl ether, at least one selected from CF2=CF-CF2-O-CF3, CF2=CF-CF2-O-C2F5, CF2=CF-CF2-O-C3F7, and CF2=CF-CF2-O-C4F9 is preferred, at least one selected from CF2=CF-CF2-O-C2F5, CF2=CF-CF2-O-C3F7, and CF2=CF-CF2-O-C4F9 is more preferred, and CF2=CF-CF2-O-CF2CF3 is further preferred.

[0066] The modified PTFE resin used in one embodiment of the present invention is a polytetrafluoroethylene resin modified with a perfluoroalkyl vinyl ether represented by the following formula (1).

[0067] CF2=CF-OR f (1)

[0068] In formula (1), R f It is a perfluoroalkyl group having 1 to 10 carbon atoms (preferably 1 to 5 carbon atoms) or a perfluoroorganic group represented by the following formula (2).

[0069]

[0070] In formula (2), n is an integer of 1-4.

[0071] Examples of the perfluoroalkyl group having 1 to 10 carbon atoms in formula (1) include perfluoromethyl, perfluoroethyl, perfluoropropyl, perfluorobutyl, perfluoropentyl, and perfluorohexyl, and preferably perfluoropropyl.

[0072] The ratio of the perfluoroalkyl vinyl ether polymerized units represented by the above formula (1) in the modified PTFE resin of the present embodiment is preferably 1% by weight or less, more preferably in the range of 0.001 to 1% by weight. When the perfluoroalkyl vinyl ether polymerized units represented by the above formula (1) are contained in the above ratio, it is easy to obtain a modified PTFE resin that exhibits thermal behavior based on the above dynamic viscoelastic properties.

[0073] In addition, since the content ratio of the perfluoroalkyl vinyl ether polymerization unit represented by the above formula (1) is within the above range, when the modified PTFE resin of this embodiment is heated and sintered, the melting between the modified PTFE particles is easily exhibited due to the thermal behavior based on the dynamic viscoelastic properties, and the molded body obtained after heating will have excellent strength.

[0074] (Thermal behavior of modified polytetrafluoroethylene resin)

[0075] The modified PTFE resin contained in the powder of the present embodiment is characterized in that it exhibits the following specific thermal behavior: that is, the storage modulus G' at 333°C obtained by dynamic viscoelasticity measurement under the conditions of frequency 1 Hz, strain 0.3%, and heating rate 3°C / min is 1.0×10 5 Below Pa.

[0076] The above storage modulus G' is 1.0×10 5 Pa or less, which can be 1.0×10 4 Pa or less, 1.0×10 3 Below Pa.

[0077] The modified PTFE resin used in the present embodiment is not particularly limited as long as it exhibits the above-mentioned specific thermal behavior. For example, a product obtained by heating (firing) the modified PTFE resin at least once can be cited, but it is not limited thereto. In the following description, a resin that has been subjected to at least one heating treatment (firing) is referred to as a "heated resin", and a so-called virgin resin that has never been subjected to even one heating treatment is referred to as an "unheated resin".

[0078] Since the powder of the present embodiment contains the modified PTFE resin exhibiting the above-mentioned thermal behavior, when a molded body is produced using the powder, strong fusion between the resin particles is exhibited by heat treatment (sintering), and a high-strength molded body is obtained.

[0079] The modified PTFE resin exhibiting the above-mentioned specific thermal behavior can be obtained, for example, by adjusting the heating rate when heating the unheated modified PTFE resin (for example, 0.01 to 20°C / minute), the maximum temperature reached (for example, a temperature above the melting point (327°C). For example, 327 to 400°C) and its insulation time (1 minute to 4.5 hours), the pressure of the pressurization treatment before the heating treatment (for example, 10 to 100 MPa), etc.

[0080] The present inventors have found that when the modified PTFE resin exhibiting the above-mentioned specific thermal behavior is heated (sintered), the particles 10 of the modified PTFE resin exhibit fusion properties and the bonding between the particles becomes strong (see Figure 3 (B) (c)), the obtained molded body 11 exhibits excellent strength (refer to Figure 3 (A) of (c)).

[0081] In addition, Figure 3 (A) and Figure 3 In (B), (a) shows a state before firing, (b) shows a state during firing, and (c) shows a state after firing.

[0082] (Melting point of modified polytetrafluoroethylene resin)

[0083] In one embodiment, the modified PTFE resin used in the present embodiment is a heated resin, and its melting point is 333° C. or less. The melting point of the heated modified PTFE resin is generally lower than that of the unheated modified PTFE resin.

[0084] (Particle size of modified polytetrafluoroethylene resin)

[0085] The median particle size D of the powder of the modified PTFE resin used in this embodiment is 50 It is less than 6000μm.

[0086] Since the median particle size D of the modified PTFE resin powder 50 When the powder is heated and sintered within the above range, the degree of adhesion between the modified PTFE particles increases, the particles are easily welded together, the obtained molded body becomes dense, and excellent strength can be obtained.

[0087] In one embodiment, the median particle size D of the powder of the modified PTFE resin is 50It can be above 1 μm, above 3 μm, above 5 μm, above 10 μm, above 50 μm, above 70 μm, above 100 μm, above 200 μm, above 500 μm, above 1000 μm, above 2000 μm, above 3000 μm or above 4000 μm; it can be below 5000 μm, below 4000 μm, below 3000 μm, below 1000 μm, below 700 μm, below 600 μm, below 500 μm or below 400 μm.

[0088] In addition, the median particle size D of the powder was measured by the method described in the examples. 50 .

[0089] In one embodiment, when the modified PTFE resin is a powder having the above-described thermal behavior and particle size, substantially no ball blocks are observed in an image of a calcined product of the powder taken with a scanning electron microscope.

[0090] In the present embodiment, the calcined product of the modified PTFE resin powder is a calcined product obtained by spreading the modified PTFE resin powder on a SUS thin plate and calcining it at a calcination temperature of 365° C. for four and a half hours.

[0091] Specifically, “substantially no knurled mass is observed” means that no knurled mass is observed in an image of the powder sintering product taken at a magnification of 10,000 times using a scanning electron microscope.

[0092] In this specification, the term "comb" refers to an object in which the crystal structure is changed by firing to form folded chain crystals, and the folded chain crystals form spherical blocks.

[0093] The inventors speculate that when the powder containing the modified PTFE resin of the present embodiment is heated and sintered, the fluidity of the modified PTFE resin constituting the powder increases, and the formation of ball blocks is suppressed while the resin particles are fused to each other (see Figure 2-5 ).

[0094] Furthermore, since the powder containing the modified PTFE resin according to the present embodiment exhibits the above-mentioned fluidity when heated, it can be suitably used in ram extrusion molding or the like in which pressure is applied while heating.

[0095] The powder of the modified PTFE resin used in the present embodiment can be obtained by pulverizing the modified PTFE resin.

[0096] There is no particular limitation on the method for pulverizing the modified PTFE resin, as long as it can be pulverized to a desired particle size. It can be carried out by a known method, for example, a blender, hammer mill, jet mill, mortar grinder, freeze grinder, etc.

[0097] The comminution can be carried out at one time using one device, or in stages using multiple devices.

[0098] For example, a single-piece modified PTFE resin may be pulverized to a desired particle size using a blender, or a single-piece modified PTFE resin may be pulverized to a predetermined particle size using a blender and then pulverized to a desired particle size using a hammer mill.

[0099] The pulverization of the modified PTFE resin involved in a certain embodiment of the present invention can also be carried out by a freeze pulverization method, that is, the resin is cooled to a frozen state for pulverization. The freeze pulverization is preferably carried out by cooling to a temperature below the glass transition temperature of the modified PTFE resin involved in a certain embodiment of the present invention, for example, preferably cooling to below -190°C, below -196°C, or even below -250°C.

[0100] (Other ingredients)

[0101] The powder of the present embodiment may contain any component other than the modified polytetrafluoroethylene resin as long as the effects of the present invention are not impaired.

[0102] The optional components are not particularly limited, and examples thereof include flame retardants, flame retardant aids, pigments, antioxidants, reflectors, shielding agents, lubricants, processing stabilizers, plasticizers, foaming agents, and fillers.

[0103] The ratio of the modified PTFE resin in the modified PTFE resin-containing powder of the present embodiment may be 90% by mass or more, 95% by mass or more, 98% by mass or more, 99% by mass or more, or 100% by mass.

[0104] [Molding body]

[0105] A molded article according to an embodiment of the present invention includes the modified polytetrafluoroethylene resin according to an embodiment of the present invention described above.

[0106] The molded product of the present embodiment may contain any component in addition to the modified polytetrafluoroethylene resin contained in the powder of one embodiment of the present invention described above, within a range not impairing the effects of the present invention.

[0107] The optional components contained in the molded body include the optional components contained in the powder according to one embodiment of the present invention described above and optional components added during the production process of the molded body.

[0108] There are no particular restrictions on the optional components that can be added during the manufacturing process of the molded body, and examples thereof include flame retardants, flame retardant aids, pigments, antioxidants, reflectors, shielding agents, lubricants, processing stabilizers, plasticizers, foaming agents, fillers, various resins (but excluding modified PTFE resins and homopolymer PTFE resins), etc.

[0109] In this case, the total content of the arbitrary components in the molded product may be 50 mass % or less, 40 mass % or less, 20 mass % or less, 10 mass % or less, 5 mass % or less, 3 mass % or less, 1 mass % or less, or 0 mass %.

[0110] The molded article according to one embodiment does not contain any fluororesin other than the modified polytetrafluoroethylene resin.

[0111] Examples of other fluororesins include polytetrafluoroethylene (PTFE) and perfluoroalkoxyalkane (PFA, tetrafluoroethylene / perfluoroalkoxyethylene copolymer resin).

[0112] Polytetrafluoroethylene (PTFE) is a homopolymer of tetrafluoroethylene (homo-PTFE).

[0113] Figure 4 Shown is a curve chart of the tensile strength of each molded body obtained by press-molding and then heating each powder of unheated homopolymer PTFE resin powder B, heated homopolymer PTFE resin powder B-1, unheated modified PTFE resin powder A, and heated modified PTFE resin powder A-1 of a certain embodiment of the powder of a certain embodiment of the present invention.

[0114] like Figure 4 As shown, the molded body of the heated modified PTFE resin powder A-1 according to one embodiment of the powder of one embodiment of the present invention has a tensile strength substantially equivalent to 95% or more of the tensile strength of the molded body using the unheated modified PTFE resin powder A.

[0115] In one embodiment, the tensile strength of the molded body may be 13 MPa or more, 14 MPa or more, 15 MPa or more, 18 MPa or more, or 20 MPa or more.

[0116] The upper limit of the tensile strength of the molded product is not particularly limited, but is usually 50 MPa or less. Alternatively, the upper limit of the tensile strength may be 24 MPa, 30 MPa, 35 MPa, 40 MPa, or 45 MPa or less.

[0117] The tensile strength of the molded body can be measured by the method described in Examples.

[0118] Figure 5 The curve graph shown is the tensile elongation of each molded body obtained by press-molding and then heating each powder of unheated homopolymer PTFE resin powder B, heated homopolymer PTFE resin powder B-1, unheated modified PTFE resin powder A, and heated modified PTFE resin powder A-1 of a certain embodiment of the powder of a certain embodiment of the present invention.

[0119] like Figure 5 As shown, the molded body using the heated modified PTFE resin powder A-1 according to a certain embodiment has a higher tensile elongation than the molded body using the unheated modified PTFE resin powder A.

[0120] In one embodiment, the tensile elongation of the molded article may be 100% or more, 150% or more, 200% or more, or 250% or more.

[0121] The upper limit of the tensile elongation of the molded article is not particularly limited, but is usually 500% or less. Alternatively, the upper limit of the tensile elongation may be 200%, 220%, 250%, 270%, 300%, 350%, 400%, or 450% or less.

[0122] The tensile elongation of the molded article was measured by the method described in Examples.

[0123] In one embodiment, a cross section of the molded article was photographed using a scanning electron microscope at a magnification of 45,000 times in a range of 2.8 μm in the horizontal direction and 2.0 μm in the vertical direction, and a continuously extending band-like structure was observed (see Figure 7-1 (b)).

[0124] On the other hand, in a scanning electrode microscope image of a cross section of a molded body obtained by heating and calcining a modified polytetrafluoroethylene resin having the same repeating unit structure as the modified PTFE resin contained in the molded body of the present embodiment but not exhibiting the prescribed thermal behavior, no continuously extending band-like structure was observed in the same manner as above (see Figure 7-2 (a), (b)).

[0125] In one embodiment, in an image obtained by taking a 20,000-fold magnification of the surface or cross section of the molded article in a lateral 2.8 μm×vertical 2.0 μm range, substantially no ball blocks are observed (see Figure 6-1 , Figure 7-1 ).

[0126] Specifically, the phrase "substantially no knurling block is observed" in the molded article of this embodiment means that no knurling block is observed in an image obtained by photographing the surface or cross section of the molded article at a magnification of 20,000 times using a scanning electron microscope.

[0127] The molded article according to one embodiment of the present invention is obtained by 50 The storage modulus G' at 333°C measured under the conditions of frequency 1 Hz, strain 0.3%, and heating rate 3°C / min is 1.0×10 5 It is obtained by compression molding and sintering a powder containing a modified polytetrafluoroethylene resin with a density of Pa or less.

[0128] In one embodiment, the molded body of the embodiment is obtained by filling the powder into a mold and pressurizing the mold, heating the mold filled with the powder, and sintering the powder filled in the mold.

[0129] In one embodiment, the molded body of the embodiment is obtained by filling the above-mentioned powder into a mold and pressurizing it, taking the compressed powder out of the mold, and then heating and firing it.

[0130] The molded product of this embodiment has the same tensile strength, tensile elongation, etc. as the molded product of any one of the above-mentioned embodiments, and substantially no knurled block is observed, and a band-like structure is observed.

[0131] [Method for producing molded article]

[0132] A method for producing a molded article according to an embodiment of the present invention comprises: a step of compression molding the powder containing the modified polytetrafluoroethylene resin according to an embodiment of the present invention; and a step of calcining.

[0133] In one embodiment, the process comprises the following steps (1) and (2):

[0134] (1) a step of filling a powder containing a modified polytetrafluoroethylene resin according to one embodiment of the present invention into a mold and applying pressure;

[0135] (2) A step of heating the mold filled with the powder to sinter the powder filled in the mold.

[0136] (Step (1) Filling and Pressurizing Powder)

[0137] The powder containing the modified PTFE resin according to one embodiment of the present invention is filled into a mold and pressurized. The pressurized powder is compressed and molded in the mold (see Figure 3 (A)(a)).

[0138] As described above, the median particle size D of the powder containing the modified PTFE resin according to one embodiment of the present invention filled into the mold is 50 It is less than 6000μm.

[0139] Since the median particle size D 50 The particle size is below 6000 μm. Therefore, when the mold filled with the powder is heated and sintered in the later-described step (2), the adhesion between the modified PTFE particles increases, the particles are easily welded, and the molded body obtained after heating becomes dense, which can obtain excellent strength.

[0140] The pressurization pressure may be 5 to 100 MPa, 20 to 60 MPa, or 30 to 50 MPa.

[0141] By applying pressure within the above range, when the powder compressed in the mold obtained in this step is sintered in the later step (2), the modified PTFE particles can be easily welded together, and the molded body obtained after heating can have excellent strength.

[0142] (Step (2) Calcination of Compressed Powder)

[0143] The mold filled with the powder is heated to sinter the powder filled in the mold (refer to Figure 3 (a) of (b)).

[0144] The calcination temperature may be 300 to 400°C, 330 to 370°C, or 360 to 370°C.

[0145] By calcining within the above temperature range, the fluidity of the modified PTFE resin can be appropriately improved, and the fusion of the modified PTFE resin particles can be facilitated, so that the molded body obtained after this step has excellent strength.

[0146] The powder filled in the mold can be fired by, for example, placing the mold filled with the powder in a heating furnace, then raising the temperature in the heating furnace at a predetermined heating rate, and maintaining the temperature at the firing temperature for a predetermined time.

[0147] When the mold filled with the powder is placed in a heating furnace and the temperature in the heating furnace is increased, the heating rate may be 0.01 to 20°C / min, 0.05 to 10°C / min, or 0.1 to 3°C / min.

[0148] By heating at the above-mentioned heating rate, the fluidity of the modified PTFE resin contained in the powder can be appropriately improved, and the fusion of the modified PTFE resin particles can be more easily performed, so that the molded body obtained after this step has excellent strength.

[0149] Regarding the temperature increase during firing, the temperature may be increased at the same temperature increase rate until the firing temperature is reached, or the temperature increase rate may be changed in stages until the firing temperature is reached.

[0150] When changing the heating rate in stages, it is preferred to increase the temperature at a prescribed heating rate until a temperature range close to the firing temperature (for example, a temperature range 1 to 20°C lower than the firing temperature) is reached, and then to set the heating rate to be lower than the previous heating rate and further increase the temperature until the firing temperature is reached.

[0151] By adjusting the heating rate as described above, a sudden increase in the fluidity of the modified PTFE resin contained in the powder can be suppressed, and the fusion of the modified PTFE resin particles can be smoothly performed, making it easy to obtain a stable bonding state between the modified PTFE resin particles.

[0152] After sintering, the mold filled with the powder can be cooled by lowering the temperature in the furnace at a predetermined temperature drop rate.

[0153] The temperature drop rate in this case is not particularly limited, and may be 0.01 to 20°C / min, 0.05 to 10°C / min, or 0.1 to 3.0°C / min.

[0154] By setting the temperature drop rate within the above range, the modified PTFE resin particles tend to remain fused to each other during cooling, and the modified PTFE resin particles tend to be stably bonded to each other in the molded body obtained after cooling.

[0155] In addition, the sintering of the molded body is not limited to the method of placing the mold filled with powder into a heating furnace and then raising the temperature in the heating furnace at a specified heating rate. It can also be carried out by, for example, placing the mold filled with powder into a heating furnace set to the sintering temperature and keeping it for a specified time.

[0156] In one embodiment, the process comprises the following steps (1), (3) and (4):

[0157] (1) a step of filling a powder containing a modified polytetrafluoroethylene resin according to one embodiment of the present invention into a mold and applying pressure;

[0158] (3) a step of removing the powder (preform) that has been compression molded in the mold from the mold;

[0159] (4) A step of heating and firing the compression-molded powder (preform).

[0160] The step (1) is as described above.

[0161] The method for taking out the powder (preform) compression-molded in the mold from the mold in the step (3) is not particularly limited, and a known method can be used.

[0162] In step (4), the compression-molded powder (preform) is fired for a predetermined time at a temperature not lower than the melting point of the resin in a hot air circulation furnace or the like. The firing method, temperature, time, etc. can be appropriately set.

[0163] The molded product of the present embodiment described above may be used after being molded into, for example, a block shape, a tube shape, or the like, or may be used after being molded into a sheet shape by skiving.

[0164] The molded article of the present embodiment described above can be suitably used as a valve seat, a gasket, a packaging material, a heat-resistant material such as a heat-resistant insulating tape, a substrate for a printed circuit board, a printed circuit board, and a release sheet.

[0165] Example

[0166] The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

[0167] [Resin]

[0168] In the following examples and comparative examples, respectively: "heated modified PTFE resin" is used to represent the modified PTFE resin involved in a certain embodiment of the present invention; "unheated modified PTFE resin" is used to represent a modified PTFE resin having the same structure as the modified PTFE resin involved in a certain embodiment of the present invention, but does not exhibit specific thermal behavior and has never been subjected to even one heating treatment; "heated homopolymer PTFE resin" is used to represent a homopolymer PTFE resin that has been subjected to one heating treatment; "unheated homopolymer PTFE resin" is used to represent a homopolymer PTFE resin that has never been subjected to even one heating treatment.

[0169] Example 1 and Comparative Example 1 (Production of Heated Modified PTFE Resin Powders A-1 to A-5)

[0170] The chips (heated modified PTFE resin) generated when the unheated modified PTFE resin ("M112", manufactured by Daikin Industries, Ltd.; hereinafter referred to as "powder A") is sintered to obtain a modified PTFE resin molded body (100mm×100mm×100mm) are processed by lathe to perform special-shaped processing are crushed into the desired particle size according to the following steps to obtain resin powder.

[0171] For the heated modified PTFE resin powders A-1 and A-2, first, the chips were cut with scissors to form cut pieces with a long diameter of 3 to 5 mm, and then coarsely crushed into powders with a particle size of less than 1 mm using a juice blender. Then, the resulting coarse powder was cooled to -196°C with liquid nitrogen and freeze-crushed using a hammer mill cooled with liquid nitrogen.

[0172] Next, the freeze-pulverized powder was classified using a sieve to obtain heated modified PTFE resin powders A-1 and A-2. The classification was performed by decreasing the sieve openings in the order of 425 μm, 300 μm, and 250 μm.

[0173] The heated modified PTFE resin A-3 was subjected to coarse pulverization by the above-mentioned chips, and then subjected to cryogenic freezing pulverization by liquid nitrogen using an ultrafine pulverizer.

[0174] The heated modified PTFE resins A-4 and A-5 were first cut with scissors to form cut pieces with a long diameter of 50 to 100 mm, and then powdered with a juice blender to a size of 10 mm or less, and then classified with a sieve with a sieve opening of 1.7 mm.

[0175] Comparative Example 2 (Production of Heated Homopolymer PTFE Resin Powder B-1)

[0176] The chips (heated homo-PTFE resin) produced when a homo-PTFE resin molded body (100 mm × 100 mm × 100 mm) obtained by sintering an unheated homo-PTFE resin ("M18", manufactured by Daikin Industries, Ltd.; hereinafter referred to as "powder B") is processed by lathe are crushed in the following steps to obtain resin powder.

[0177] First, chips (heated homopolymer PTFE resin) were cut with scissors to form cut pieces with a major diameter of 1 mm or less, and 1 g of the obtained sample was weighed and placed in a 12 mL SUS container together with a tungsten carbide steel ball.

[0178] Next, the sample in the container was pulverized using a freezer pulverizer ("JFC-300", manufactured by Japan Analytical Industry Co., Ltd.) under the conditions of a precooling time of 10 minutes and a pulverizing time of 10 minutes to obtain a heated homopolymer PTFE resin powder B-1 (hereinafter referred to as "powder B-1").

[0179] <Median particle size D 50 Measurements>

[0180] 100 particles were randomly selected from powders A-1, A-2, A-4, A-5 obtained in Example 1 and powder B-1 obtained in Comparative Example 1, and the major and minor diameters of the particles were measured using a microscope. The arithmetic mean of the major and minor diameters of the particles was taken as the particle size, and the median value of the 100 particle sizes was taken as the median particle size D. 50 .

[0181] The particle size of the powder A-3 obtained in Example 1 was measured using a particle size distribution analyzer under the following apparatus and conditions, and the particle size was set to a value equal to the particle size corresponding to 50% of the cumulative (volume basis) particle size distribution.

[0182] Measuring device: Laser diffraction particle size distribution measuring device "Mastersizer 3000" (manufactured by Malvern Panalytical Co., Ltd.)

[0183] Measuring method: dry

[0184] Vacuum degree: 4 bar

[0185] The median particle size D of each powder obtained 50 Shown in Table 1.

[0186] [Table 1]

[0187] sample <![CDATA[Median particle size D 50 > Heated modified PTFE resin powder A-1 259μm Heated modified PTFE resin powder A-2 513μm Heated modified PTFE resin powder A-3 5μm Heated modified PTFE resin powder A-4 4967μm Heated modified PTFE resin powder A-5 6137μm Heated homopolymer PTFE resin powder B-1 18μm

[0188] <Dynamic viscoelasticity (DMA) measurement>

[0189] Powder A, powder B, powder A-1, and powder B-1 were respectively press-molded at a molding surface pressure of 35 MPa to obtain cylindrical storage modulus measurement samples of 15 mm in diameter and 2 mm in height.

[0190] The storage modulus G' of each sample was measured using the following apparatus and conditions.

[0191] Measuring device: RSA-G2 (manufactured by TA Instruments Japan Co., Ltd.), measuring lower limit: 1.0×10 3 Pa

[0192] Measurement conditions: temperature 60~370℃, heating rate 3℃ / min, strain 0.3%, frequency: 1Hz

[0193] Measurement mode: Compression mode

[0194] The measurement results are shown in Figure 1 .

[0195] exist Figure 1 In the figure, curve (A) is the storage modulus G' of the unheated modified PTFE resin powder A, curve (B) is the storage modulus G' of the unheated homopolymer PTFE resin powder B, curve (A-1) is the storage modulus G' of the heated modified PTFE resin powder A-1, and curve (B-1) is the storage modulus G' of the heated homopolymer PTFE resin powder B-1.

[0196] like Figure 1 As shown, in the unheated modified PTFE resin powder A, the unheated homopolymer PTFE resin powder B, and the heated homopolymer PTFE resin powder B-1, the storage modulus does not change significantly within the temperature range of 60 to 370°C.

[0197] On the other hand, in the heated modified PTFE resin powder A-1, a behavior in which the storage elastic modulus significantly decreases at around 300°C was confirmed.

[0198] <Measurement of Melting Point>

[0199] The melting point of each sample (powder) was measured using the following apparatus and conditions. The results are shown in Table 3.

[0200] The melting point is the melting peak temperature in the resulting heat of melting curve.

[0201] Measuring device: DSC8500 (manufactured by PerkinElmer)

[0202] Measurement conditions: Heating rate 10℃ / min

[0203] <SEM observation of powder samples>

[0204] Table 2 shows the contents of the powder samples for SEM observation and their correspondence with the drawing numbers of the SEM observation images.

[0205] [Table 2]

[0206]

[0207] (FE-SEM measurement conditions)

[0208] Measuring device: FE-SEM (field emission scanning electron microscope) "SU8220" (manufactured by Hitachi High-Technologies Corporation)

[0209] Accelerating voltage: 3kV

[0210] Emission current: 5μA

[0211] Measurement magnification: 5000 times

[0212] (Preparation of unfired powder samples for SEM observation)

[0213] Each sample of powder A, powder B, powder A-1, and powder B-1 was subjected to platinum vapor deposition for 10 seconds to obtain an unfired powder sample for FE-SEM observation.

[0214] In addition to the above samples, samples of unheated homopolymer PTFE resin powder ("M12", manufactured by Daikin Industries, Ltd.; hereinafter referred to as "powder C") and unheated homopolymer PTFE resin powder ("7-J", manufactured by Mitsui Chemours Fluoroproducts Co., Ltd.; hereinafter referred to as "powder D") were subjected to 10 seconds of platinum vapor deposition to obtain unfired powder samples for FE-SEM observation.

[0215] (SEM observation of unfired powder sample)

[0216] The unfired powder samples obtained above (unheated resin powders A to D and heated resin powder A-1 and heated resin powder B-1) were observed using FE-SEM (field emission scanning electron microscope) under the following conditions.

[0217] The observed image is represented as Figure 2-1 to Figure 2-6 The “before firing” in the text.

[0218] (Preparation of sintered powder samples for SEM observation)

[0219] The samples shown in Table 2 were spread on SUS sheets, respectively, and placed in an electric furnace. They were fired at a furnace temperature of 365° C. for 4.5 hours.

[0220] Each sample obtained after firing was subjected to platinum vapor deposition for 10 seconds to obtain a fired powder sample for FE-SEM observation.

[0221] (SEM observation of sintered powder sample)

[0222] The fired powder samples obtained above (resin powders A to D that were not heated after firing, and heated resin powder A-1 and heated resin powder B-1) were observed using FE-SEM (field emission scanning electron microscope) under the following conditions.

[0223] The conditions for FE-SEM observation were similar to those for “SEM observation of unfired powder sample” except that the acceleration voltage was 3 to 5 kV and the measurement magnification was 1000 times, 5000 times, and 10000 times.

[0224] The observed image is represented as Figure 2-1 to Figure 2-6 "After firing" in.

[0225] In addition, Figure 2-5 and Figure 2-6 Among the images of the fired powder samples shown, the images in the upper column and the images in the lower column are SEM images of different parts of the same sample.

[0226] like Figure 2-1 to Figure 2-6 As shown in FIG. 1 , it was confirmed that the unheated modified PTFE resin powder A and the unheated homopolymer PTFE resin powders B to D all formed spherical blocks after sintering (the unheated modified PTFE resin powder A: Figure 2-1 Arrows (2) and (4) in the figure indicate unheated homopolymer PTFE resin powders B and D: Figure 2-2 and Figure 2-4 ).

[0227] Among them, it was confirmed that in the unheated modified PTFE resin powder A, beaded connections were generated on the surface of the ball blocks ( Figure 2-1 ).

[0228] In contrast, in the heated modified PTFE resin powder A-1, it was confirmed that no ball blocks were generated after sintering, and that the particle surfaces were formed with irregularities, showing a state in which the particles were fused to each other ( Figure 2-5 ).

[0229] In the unheated resin powder, it was confirmed that the unheated homopolymer PTFE resin powder C had a large amount of ball blocks generated, and a large number of ball blocks were connected and bonded to each other ( Figure 2-3 On the other hand, it was confirmed that the heated homopolymer PTFE resin powder B-1 generated a ball block after sintering ( Figure 2-6 arrow (5) in the figure), but compared with the unheated homopolymer PTFE resin powder B ( Figure 2-2 ). In the heated homopolymer PTFE resin powder B-1, it was confirmed that there were sites where the globules were entangled with each other, but it was confirmed that there was no morphology in which a large number of globules were connected to each other as in the unheated homopolymer PTFE resin powder B ( Figure 2-6 ).

[0230] [Molding body]

[0231] Example 2

[0232] 20 g of the heated modified PTFE resin powder A-1 obtained in Example 1 was weighed and filled into a cylindrical mold with an inner diameter of 15 mm, and compression molding was performed for 1 minute by applying a pressing pressure of 35 MPa from the top (molding step (refer to Figure 3 (A)(a)).

[0233] Next, the upper and lower surfaces of the compression-molded cylindrical mold were sandwiched between metal flanges and fixed with bolts and nuts. The bolts on the upper surface were loosened, and a 1 mm gasket was sandwiched. In this state, the bolts were tightened to remove the gasket.

[0234] Next, the cylindrical mold filled with the heated modified PTFE resin powder A-1 was placed in an electric furnace and sintered at a temperature of 365° C. in the electric furnace for 4.5 hours (refer to Figure 3 (b) of (A) (firing step) to obtain a cylindrical molded body with a diameter of 15 mm and a height of 50 mm (refer to Figure 3 (A) of (c)).

[0235] Examples 3 to 5 and Comparative Example 3

[0236] A molded body was obtained in the same manner as in Example 2 except that the heated modified PTFE resin powders A-2 to A-5 were used instead of the heated modified PTFE resin powder A-1 in Example 2.

[0237] Comparative Example 4

[0238] A molded body was obtained in the same manner as in Example 2 except that unheated modified PTFE resin powder A was used instead of heated modified PTFE resin powder A-1 in Example 2 and the molded body was taken out of the mold after compression molding (molding step) and subjected to a sintering step.

[0239] Comparative Example 5

[0240] A molded body was obtained in the same manner as in Example 2 except that unheated homopolymer PTFE resin powder B was used instead of heated modified PTFE resin powder A-1 in Example 2 and the molded body was taken out of the mold after compression molding (molding step) and subjected to a sintering step.

[0241] Comparative Example 6

[0242] A molded body was obtained in the same manner as in Example 2 except that unheated modified PTFE resin powder A was used instead of heated modified PTFE resin powder A-1 in Example 2. The molded body obtained in Comparative Example 6 was used as a subject for SEM observation of a molded body described later.

[0243] <Tensile test>

[0244] The molded bodies obtained in Examples 2 to 5 and Comparative Examples 3 to 5 were cut with a band saw to obtain strip-shaped test pieces (50 mm in length, 15 mm in width, and 1 mm in thickness).

[0245] The obtained test piece was punched out into a No. 7 dumbbell shape using a punching machine to obtain a sample for a tensile test.

[0246] After measuring the thickness of the obtained tensile test sample, a tensile test was performed using a desktop universal tester (manufactured by Shimadzu Corporation) at a tensile speed of 200 mm / min, and the strength of the sample at break (the value obtained by dividing the tensile load value by the cross-sectional area of ​​the test piece) and the sample length were measured, and the tensile strength (MPa) and tensile elongation (%) were calculated. The tensile elongation was calculated by the following formula (A). The results are shown in Table 3.

[0247] Tensile elongation (%) = (L-L0) / L0×100(A)

[0248] L0: Sample length before testing

[0249] L: sample length at break

[0250] Table 3 shows the ratio (%) of the tensile strength of each molded body using the heated modified PTFE resin powders A-1 to A-5, when the tensile strength of the molded body of Comparative Example 4 using the unheated modified PTFE resin powder A is set to 100%.

[0251] Table 3 shows the properties of the types of raw resin powders (heated modified PTFE resin powders A-1 to A-5, unheated modified PTFE resin powder A, unheated homopolymer PTFE resin powder B, and heated homopolymer PTFE resin powder B-1) used in the manufacture of the molded bodies of Examples 2 to 5 and Comparative Examples 3 to 6, as well as their behaviors during sintering (formation of lumps, storage modulus), and the tensile strength and tensile elongation of the molded bodies obtained using the raw resin powders.

[0252]

[0253] In addition, the "formation of the ball block" in Table 3 was determined based on the following indexes.

[0254] ○: The existence of the korbot block can be confirmed.

[0255] ×: It can be confirmed that there is no knurled block.

[0256] As shown in Table 3, the molded bodies using the heated modified PTFE resin powders A-1 to A-4 and the molded body using the unheated modified PTFE resin powder A showed substantially equivalent tensile strength and tensile elongation.

[0257] It can be seen that compared with the comparative example using unheated modified PTFE resin powder, the ratio (%) of the tensile strength of the molded bodies of Examples 2 to 5 is increased by more than 50%, more than 60%, more than 70%, more than 80% or more than 90%, and that by using powder containing modified PTFE resin having a specific particle size range and thermal behavior, a molded body with suppressed strength reduction is obtained.

[0258] In the heated modified PTFE resin powder A-1, it was confirmed that no ball blocks were generated during the sintering process (refer to Figure 2-5 ), the firing process shows Figure 1 The thermal behavior of the dynamic viscoelastic properties shown above generates fluidity, and the particles become firmly bonded to each other (refer to Figure 2-5 Therefore, the inventors infer that the molded body using the heated modified PTFE resin powder A-1 can achieve a strength substantially equivalent to that of the molded body using the unheated modified PTFE resin powder A.

[0259] On the other hand, although the amount of lumps generated during the sintering process of the heated homopolymer PTFE resin powder B-1 was not as large as that of the sintering of the unheated homopolymer PTFE resin powder B (see Figure 2-6 ), but due to poor fluidity during the sintering process, the molded body using the heated homopolymer PTFE resin powder B-1 did not show the same degree of tensile strength and tensile elongation as the molded body using the heated modified PTFE resin powder A-1.

[0260] The particle size (D 50 ) is 4967 μm, and the tensile strength and tensile elongation of the molded body using this powder are not significantly reduced compared with the molded body using the unheated modified PTFE resin powder A.

[0261] In contrast, it can be seen that: using the particle size (D 50 The tensile strength and tensile elongation of the molded body of the heated modified PTFE resin powder A-5, whose particle size was as large as 6137 μm, were significantly lower than those of the molded body using the unheated modified PTFE resin powder A.

[0262] <SEM observation of molded body>

[0263] (Molding body surface)

[0264] A portion with a plane size of 1 mm×9 mm on the surface of the molded products obtained in Example 2 and Comparative Example 6 was observed using FE-SEM (field emission scanning electron microscope).

[0265] The conditions for FE-SEM observation were the same as those for "SEM observation of unfired powder sample", except that the acceleration voltage was set to 1 to 5 kV and the measurement magnification was set to 20,000 times. The observed image of the molded body of Example 2 is shown in FIG. Figure 6-1 The observed image of the molded body of Comparative Example 6 is shown in Figure 6-2 .

[0266] (Molding body cross section)

[0267] After the molded bodies obtained in Example 2 and Comparative Example 6 were cut, they were cooled in a liquid nitrogen environment, and the 1 mm×9 mm cross-section exposed by splitting the cut portion with a hammer was observed using FE-SEM (field emission scanning electron microscope).

[0268] The FE-SEM observation conditions were the same as those in the “SEM observation of the unfired powder sample” except that the acceleration voltage was 1 kV and the measurement magnification was 20000 times and 45000 times.

[0269] The cross-sectional observation image of the molded body of Example 2 is shown in Figure 7-1 The cross-sectional observation image of the molded body of Comparative Example 6 is shown in Figure 7-2 .exist Figure 7-1 and Figure 7-2 In the figure, (a) is an image at a magnification of 20,000 times, and (b) is an image at a magnification of 45,000 times.

[0270] like Figure 6-1 and Figure 7-1 As shown, it was confirmed that the surface and cross section of the molded body obtained using the heated modified PTFE resin powder A-1 had almost no lumps.

[0271] In addition, if Figure 7-1 As shown in FIG. 1 , it was confirmed that in the cross section of the molded body obtained using the heated modified PTFE resin powder A-1, at 20000 times ( Figure 7-1 (a)) and 45000 times ( Figure 7-1 A continuously extended band structure was confirmed at a magnification of (b).

[0272] In contrast, Figure 7-2 As shown, in the cross section of the molded body obtained using the unheated modified PTFE resin powder A, whether it is 20000 times ( Figure 7-2(a)) and 45000 times ( Figure 7-2 At any magnification of (b)), no continuously extended band structure was confirmed.

[0273] [Possibility of Industrial Application]

[0274] The molded body formed using the modified PTFE resin powder of the present invention can be suitably used as valve seats, gaskets, packaging materials, heat-resistant materials such as heat-resistant insulating tapes, substrates for printed circuit boards, printed circuit boards, and release sheets, but is not limited thereto.

[0275] Although several embodiments and / or examples of the present invention have been described in detail above, those skilled in the art can easily make a large number of changes to these illustrative embodiments and / or examples without substantially departing from the novel teachings and effects of the present invention. Therefore, these large number of changes are also included in the scope of the present invention.

[0276] The contents of the documents described in this specification and the applications on which the priority of this application based on the Paris Convention are based are all cited here.

Claims

1. A powder containing a modified polytetrafluoroethylene resin, wherein: The median particle size D of the powder 50 6000μm or less, The storage modulus G' of the powder at 333°C was 1.0×10 5 Below Pa.

2. The powder containing modified polytetrafluoroethylene resin according to claim 1, wherein In an image of a sintered product obtained by sintering the powder at 365° C. for 4.5 hours and photographed at a magnification of 10,000 times using a scanning electron microscope, substantially no ball blocks were observed.

3. The powder containing modified polytetrafluoroethylene resin according to claim 1 or 2, wherein: The melting point of the modified polytetrafluoroethylene resin is below 333°C.

4. A molded body, wherein The molded body is obtained by 50 The storage modulus G' at 333°C measured under the conditions of frequency 1 Hz, strain 0.3%, and heating rate 3°C / min is 1.0×10 5 It is obtained by compression molding and sintering a powder containing a modified polytetrafluoroethylene resin with a density of Pa or less.

5. The molded article according to claim 4, wherein The tensile strength of the molded body is 13 MPa or more.

6. The molded article according to claim 4 or 5, wherein The tensile elongation of the molded body is 100% or more.

7. The molded article according to any one of claims 4 to 6, wherein In an image of the surface or cross section of the molded body taken at a magnification of 20,000 times using a scanning electron microscope, substantially no knurled block was observed.

8. The molded article according to any one of claims 4 to 7, wherein In an image obtained by photographing a cross section of the molded product at a magnification of 45,000 times using a scanning electron microscope, the presence of a continuously extending band-like structure was confirmed.

Images