Composition, molded body, coated electric wire, and method for producing composition

Abstract

Provided is a composition and the like that can give a molded article with excellent surface smoothness. [Solution] A composition comprising a copolymer containing TFE units and PAVE units, wherein the content of TFE units is 93.0 to 98.0 mass% based on all monomer units of the copolymer, the content of PAVE units is 2.0 to 7.0 mass% based on all monomer units of the copolymer, the MFR is 1.0 to 40.0 g / 10 min, in a melting curve observed by heating the composition from 200°C to 350°C at 10°C / min using a differential scanning calorimeter, the proportion A of the peak area determined from the curve from 315°C to 330°C and a straight line in the melting curve to the peak area showing the heat of fusion is 1% to 20%, and the slope of the straight line connecting the heat flow at 315°C and the heat flow at 320°C is a positive value.

Description

[Technical Field]

[0001] The present disclosure relates to a composition, a molded article, a coated electric wire, and a method for producing the composition. [Background technology]

[0002] A copolymer of tetrafluoroethylene and perfluoro(alkyl vinyl ether) (hereinafter referred to as "PFA") is known as a melt-processable fluororesin that has excellent mechanical, chemical, and electrical properties. PFA also has excellent heat resistance, chemical resistance, and purity.

[0003] For example, Patent Document 1 describes a melt-processable tetrafluoroethylene / fluoroalkoxytrifluoroethylene copolymer composition that contains polytetrafluoroethylene having a crystallization temperature of 305°C or higher and a heat of crystallization of 50 J / g or higher. Non-Patent Document 1 describes the addition of polytetrafluoroethylene (hereinafter also referred to as "PTFE") as a nucleating agent to a molding material to make spherulites finer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 7-70397 [Non-patent literature]

[0005] [Non-Patent Document 1] Netsu Sokutei, 38(3), p77-82 Summary of the Invention [Problem to be solved by the invention]

[0006] In the field of semiconductor manufacturing, the threshold size for what is considered a pattern defect is shrinking as integrated circuits become more miniaturized and integrated. One of the causes of defects is the contamination of chemicals by metal ions from the chemical supply system of semiconductor manufacturing equipment. The PFA molded body attached to the chemical supply system is also a source of metal ions. One of the causes of metal contamination of PFA molded bodies is the presence of irregularities on the surface of the PFA molded body. If the surface of the PFA molded body is uneven, contaminants are more likely to remain in the irregularities. For example, Non-Patent Document 1 describes adding PTFE as a nucleating agent to refine spherulites, but since the PTFE added as a nucleating agent itself becomes a source of contamination, there is a need to improve the surface smoothness of PFA molded products without adding a nucleating agent.

[0007] In view of the above circumstances, an object of one embodiment of the present disclosure is to provide a composition that can provide a molded article having excellent surface smoothness, and a method for producing the composition. Another problem to be solved by another embodiment of the present disclosure is to provide a molded article and a coated electric wire using the composition. [Means for solving the problem]

[0008] Means for solving the above problems include the following aspects. <1> A composition comprising a copolymer including tetrafluoroethylene-based structural units and perfluoro(alkyl vinyl ether)-based structural units, the content of structural units based on tetrafluoroethylene is 93.0 to 98.0 mass% based on all monomer units of the copolymer, the content of structural units based on perfluoro(alkyl vinyl ether) is 2.0 to 7.0 mass% based on all monomer units of the copolymer; The melt flow rate measured at a temperature of 372°C is 1.0 to 40.0 g / 10 min, In a melting curve observed by heating the composition from 200°C to 350°C at a rate of 10°C / min using a differential scanning calorimeter, a peak area indicating the heat of fusion determined by drawing a straight line between points before and after the melting peak where the melting curve departs from the baseline and points where the melting curve returns to the baseline has a peak area determined by the curve from 315°C to 330°C in the melting curve and the straight line, the proportion A of the peak area determined by the straight line is 1 to 20%, and the slope of the straight line connecting the heat flow at 315°C and the heat flow at 320°C is a positive value. composition. <2> 2. The composition of claim 1, wherein the perfluoro(alkyl vinyl ether)-based constitutional units include perfluoro(propyl vinyl ether)-based constitutional units. <3> The melt flow rate measured at a temperature of 372°C is 1.0 to 19.0 g / 10 min. <1> or <2> The composition described in <4> Copolymer main chain carbon number 10 6 the total number of functional groups selected from the group consisting of -CF=CF, -CFH, -COF, -COOH, -COOCH, -CONH, and -CHOH per unit is 50 or less; <1> ~ <3> The composition according to any one of the preceding claims. <5> Percentage A is 5-20%. <1> ~ <4> The composition according to any one of the preceding claims. <6> <1> ~ <5> A molded article of the composition according to any one of the above. <7> A tube, a joint, a sheet, a nut, a tank, an electric wire coating material, or a compressed member. <6> The molded article according to claim 1. <8> a conductor; and a surface of the conductor, <1> ~ <5> and a coating layer comprising the composition according to any one of the above. <9> The method includes using tetrafluoroethylene and perfluoro(alkyl vinyl ether) as raw materials, polymerizing them by a solution polymerization method, and producing a composition containing a copolymer containing structural units based on tetrafluoroethylene and structural units based on perfluoro(alkyl vinyl ether), the content of structural units based on tetrafluoroethylene is 93.0 to 98.0 mass% based on all monomer units of the copolymer, the content of structural units based on perfluoro(alkyl vinyl ether) is 2.0 to 7.0 mass% based on all monomer units of the copolymer; The melt flow rate measured at a temperature of 372°C is 1.0 to 40.0 g / 10 min, A method for producing a composition, wherein, during the polymerization, when 5 to 12 mol % of perfluoro(alkyl vinyl ether) has been consumed relative to the amount of perfluoro(alkyl vinyl ether) used at the start of polymerization, tetrafluoroethylene is added in an amount of 15 to 65 mol % relative to the total amount of perfluoro(alkyl vinyl ether) and tetrafluoroethylene used at the start of polymerization. <10> The polymerization is carried out in a liquid medium comprising a hydrofluoroether; <9> A method for producing the composition described above. <11> The hydrofluoroether is 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether; <10> A method for producing the composition described above. [Effects of the Invention]

[0009] An object of one embodiment of the present disclosure is to provide a composition that can produce a molded article having excellent surface smoothness, and a method for producing the composition. Another problem to be solved by another embodiment of the present disclosure is to provide a molded article and a coated electric wire using the composition. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram for explaining the ratio A. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, modes for carrying out embodiments of the present disclosure will be described in detail. However, the embodiments of the present disclosure are not limited to the following embodiments. In the following embodiments, components (including element steps, etc.) are not essential unless otherwise specified. The same applies to numerical values and their ranges, and they do not limit the embodiments of the present disclosure.

[0012] In the present disclosure, the term "process" includes not only a process that is independent of other processes, but also a process that cannot be clearly distinguished from other processes as long as the purpose of the process is achieved. In the present disclosure, numerical ranges indicated using "to" include the numerical values before and after "to" as the minimum and maximum values, respectively. In the numerical ranges described in stages in this disclosure, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in the numerical ranges described in this disclosure, the upper or lower limit value of that numerical range may be replaced with a value shown in the examples. In the present disclosure, each component may contain multiple substances corresponding to the component. When multiple substances corresponding to each component are present in the composition, the content or amount of each component means the total content or amount of the multiple substances present in the composition, unless otherwise specified. In the present disclosure, a combination of two or more preferred embodiments is a more preferred embodiment. In the present disclosure, a "polymer" is a compound formed by polymerizing monomers, i.e., a "polymer" has a plurality of structural units. In the present disclosure, a "copolymer" is a compound obtained by copolymerizing two or more types of monomers. A copolymer containing units based on monomer X and units based on monomer Y is a compound obtained by copolymerizing at least monomer X and monomer Y, and may or may not further contain other monomers. In the present disclosure, the term "unit" refers collectively to an atomic group derived from one molecule of the monomer that is formed directly by polymerizing the monomer, and an atomic group obtained by chemically converting a part of the atomic group. Hereinafter, in some cases, a unit derived from an individual monomer will be referred to by the name of the monomer followed by "unit."

[0013] <Composition> The composition of the present disclosure is a composition containing a copolymer including structural units based on tetrafluoroethylene and structural units based on perfluoro(alkyl vinyl ether). The copolymer contained in the composition of the present disclosure has a content of structural units based on tetrafluoroethylene of 93.0 to 98.0 mass% based on all monomer units of the copolymer, and a content of structural units based on perfluoro(alkyl vinyl ether) of 2.0 to 7.0 mass% based on all monomer units of the copolymer. The composition of the present disclosure has a melt flow rate of 1.0 to 40.0 g / 10 min measured at a temperature of 372°C. In the composition of the present disclosure, a melting curve is observed by heating the composition from 200°C to 350°C at 10°C / min using a differential scanning calorimeter. The peak area is determined by connecting the points where the melting curve deviates from the baseline and the points where it returns to the baseline around the melting peak. The peak area, which indicates the heat of fusion, is determined by connecting the curve from 315°C to 330°C in the melting curve and the line. The proportion A of the peak area determined by the line is 1% to 20%; and the slope of the line connecting the heat flow at 315°C and the heat flow at 320°C is positive.

[0014] In particular, the composition of the present disclosure has the above proportion A of 1% to 20%, and the slope of the line connecting the heat flow at 315°C and the heat flow at 320°C is a positive value, thereby producing a molded product with excellent surface smoothness. The reason for this is not clear, but is speculated as follows.

[0015] The peak area determined by the melting curve from 315°C to 330°C and the straight line is due to the copolymer containing units based on tetrafluoroethylene and units based on perfluoro(alkyl vinyl ether). The percentage A corresponds to the proportion of components in the copolymer that have a low content of units based on perfluoro(alkyl vinyl ether) and therefore higher crystallinity. When the copolymer melted during melt molding is cooled, recrystallization typically begins with the highly crystalline components, resulting in spherulites. If the percentage A is 1 to 20%, the spherulites formed in the early stages of cooling act as nucleating agents, and the main components that did not recrystallize in the early stages of cooling begin to recrystallize near the spherulites while the degree of supercooling is still low. Therefore, the diameter of the spherulites in the copolymer at the end of cooling is small. This effect allows for the production of molded articles with excellent surface smoothness without the addition of PTFE as a nucleating agent. When PTFE is added as a nucleating agent, the main component PFA and the additive PTFE have very different phase transition behaviors and molecular structures, so they are not completely compatible even after melt molding. In this case, PFA-derived spherulites form from the incompatible PTFE-derived spherulites, which can result in a distribution in the degree of supercooling required for crystallization during cooling. This can result in a distribution in spherulite diameter and a distribution in the surface smoothness, even with the addition of PTFE. When PTFE is added, the melting curve measured by differential scanning calorimetry has two peaks of heat of fusion. In this case, the slope of the heat flow at 315°C and the heat flow at 320°C is negative because the peak of heat of fusion derived from PTFE exists in the temperature range higher than 320°C. In other words, the composition of the present disclosure, in which the slope of the heat flow at 315°C and the heat flow at 320°C are positive, does not have a peak of heat of fusion derived from PTFE, and the components in the composition are easily and uniformly compatible, so there is no distribution in the diameter of the spherulites produced, and a molded product with excellent surface smoothness can be obtained without adding PTFE.

[0016] Hereinafter, a copolymer containing units based on tetrafluoroethylene and units based on perfluoro(alkyl vinyl ether) will also be referred to as "the copolymer," the units based on tetrafluoroethylene will also be referred to as "TFE units," and the units based on perfluoro(alkyl vinyl ether) will also be referred to as "PAVE units."

[0017] Since the compositions described in Patent Documents 1 and 2 contain PTFE, in a melting curve observed by heating the composition from 200°C to 350°C at a rate of 10°C / min using a differential scanning calorimeter, the slope of the line connecting the heat flow at 315°C and the heat flow at 320°C is not a positive value.

[0018] [DSC measurement] In the composition of the present disclosure, in a melting curve observed by using a differential scanning calorimeter (DSC) to raise the temperature of the composition from 200°C to 350°C at 10°C / min, the peak area indicating the heat of fusion determined by drawing a straight line between the point where the melting curve departs from the baseline and the point where the melting curve returns to the baseline around the melting peak has a peak area determined by the curve from 315°C to 330°C in the melting curve and the straight line, which accounts for 1% to 20%.

[0019] In a melting curve observed by heating a composition from 200°C to 350°C at a rate of 10°C / min using a DSC, the peak area determined by connecting the points where the melting curve departs from the baseline and the points where it returns to the baseline around the melting peak indicates the heat of fusion.

[0020] The heat of fusion of the composition of the present disclosure is preferably 10 to 50 J / g, more preferably 15 to 40 J / g, and even more preferably 17 to 30 J / g, from the viewpoint of reducing the amount of heat required during melt molding.

[0021] The composition of the present disclosure can produce a molded article with excellent surface smoothness by having a ratio A of the peak area determined from the curve from 315°C to 330°C in the melting curve and the above straight line to the peak area indicating the heat of fusion of 1% to 20%.

[0022] FIG. 1 is a schematic diagram for explaining the ratio A. In Figure 1, the melting curve is represented by curve X. Line Y is a straight line connecting the points where the melting curve departs from the baseline and returns to it before and after the melting peak. The area enclosed by the curve X and the line Y is the peak area indicating the heat of fusion. The shaded area in FIG. 1 is the peak area determined by the curve from 315° C. to 330° C. in the melting curve and the line Y. In FIG. 1, ratio A is the ratio of the area of the peak indicated by the diagonal line to the area of the peak indicating the heat of fusion.

[0023] When the proportion A is 1% or more, the nucleating effect of the copolymer containing a large amount of TFE units in the copolymer contained in the composition results in excellent surface smoothness of the molded article. When the proportion A is 20% or less, the components contained in the composition are easily compatible with each other, and the molded article has excellent surface smoothness.

[0024] From the viewpoint of further improving the smoothness of the surface of the molded article, the ratio A is preferably from 1 to 20%, and more preferably from 5 to 20%.

[0025] Examples of methods for obtaining a composition in which the ratio A is 1% to 20% include a method of dry-blending powders or pellets of copolymers having different contents of TFE units and PAVE units, a method of wet-blending dispersions, and a method for producing a composition according to the present disclosure described below, with the method for producing a composition according to the present disclosure described below being preferred.

[0026] Furthermore, in the melting curve of the composition of the present disclosure, which is observed by heating the composition from 200°C to 350°C at a rate of 10°C / min using DSC, the slope of the line connecting the heat flow at 315°C and the heat flow at 320°C (hereinafter also referred to as "slope T") is a positive value.

[0027] A positive value of the slope T means that the heat flow value at 315°C is smaller than the heat flow value at 320°C.

[0028] The slope T is calculated based on the following formula: Slope T [mW / (mg·℃)] = ("Heat flow value at 320℃" - "Heat flow value at 315℃") / 5

[0029] The heat flow value at 315°C is preferably -0.60 to -0.10 mW / mg, more preferably -0.55 to -0.15 mW / mg. The heat flow value at 320°C is preferably -0.55 to -0.10 mW / mg, more preferably -0.55 to -0.15 mW / mg. The slope T is preferably 0.0010 to 0.0200 mW / (mg·°C), and more preferably 0.0020 to 0.0150 mW / (mg·°C).

[0030] Since the melting point of PTFE is 327°C, when the composition contains PTFE, the melting curve becomes bimodal and the slope T is a negative value.

[0031] A method for obtaining a composition in which the slope T is a positive value includes, for example, adjusting the mixing ratio of copolymers having different contents of TFE units and PAVE units.

[0032] [Melt flow rate] The melt flow rate (MFR) of the composition is 1.0 to 40.0 g / 10 min. When the MFR is 1.0 g / 10 min or more, the melt moldability is excellent. When the MFR is 40.0 g / 10 min or less, the molded article will have excellent mechanical strength.

[0033] From this viewpoint, the MFR of the composition is preferably from 1.0 to 40.0 g / 10 min, more preferably from 1.0 to 19.0 g / 10 min, and even more preferably from 2.0 to 18.0 g / 10 min. A specific example of a method for adjusting the MFR of the present copolymer within the above range is to adjust the molecular weight of the present copolymer. The higher the molecular weight of the present copolymer, the smaller the MFR. The MFR of a copolymer means the mass (g) of the copolymer flowing through an orifice having a diameter of 2.095 mm and a length of 8 mm in 10 minutes, measured at a temperature of 372°C under a load of 5 kg in accordance with ASTM D1238. The copolymer and other components contained in the composition will be described in detail below.

[0034] [This copolymer] The copolymer contains TFE units and PAVE units. The TFE units account for 93.0 to 98.0 mass % of all monomer units in the copolymer. The PAVE unit content is 2.0 to 7.0 mass % based on the total monomer units of the copolymer.

[0035] From the viewpoint of increasing the strength of the molded article, the content of the TFE units is preferably 93.0% by mass or more, more preferably 93.5% by mass or more, and even more preferably 94.0% by mass or more, based on the total monomer units of the copolymer. From the viewpoint of increasing the flexibility of the molded article, the content of the TFE units is preferably 98.0% by mass or less, more preferably 97.5% by mass or less, and even more preferably 97.0% by mass or less, based on the total monomer units of the copolymer.

[0036] From the viewpoint of improving the flexibility of the molded article, the content of PAVE units is preferably 2.0% by mass or more, more preferably 2.5% by mass or more, and even more preferably 3.0% by mass or more, based on the total monomer units contained in the copolymer. From the viewpoint of improving the crystallinity of the copolymer and the strength of the molded article, the content of PAVE units is preferably 7.0% by mass or less, more preferably 6.5% by mass or less, and even more preferably 6.0% by mass or less, based on the total monomer units contained in the copolymer.

[0037] As the PAVE, a monomer represented by formula (1) is preferred. CF2=CF-O-Rf 1 (1) In formula (1), Rf 1 represents a perfluoroalkyl group having 1 to 10 carbon atoms. 1From the viewpoint of achieving better polymerization reactivity, the number of carbon atoms in the perfluoroalkyl group represented by the following formula is preferably 1 to 8, more preferably 1 to 6, even more preferably 1 to 5, and particularly preferably 1 to 3. The perfluoroalkyl group may be linear or branched.

[0038] Specific examples of PAVE include perfluoro(methyl vinyl ether) (PMVE), perfluoro(ethyl vinyl ether) (PEVE), and perfluoro(propyl vinyl ether) (PPVE). PMVE or PPVE is preferred, with PPVE being more preferred, due to their excellent balance between raw material cost and ease of handling during polymerization. PAVE may be used alone or in combination of two or more types.

[0039] In this copolymer, from the viewpoint of exhibiting the properties of the TFE units and PAVE units well and from the viewpoint of making the molded body less likely to deform easily by compression or tension, the total content of the TFE units and PAVE units is preferably 95.0 mass% or more, more preferably 98.0 mass% or more, even more preferably 99.0 mass% or more, and may be 100.0 mass% based on the total monomer units contained in this copolymer.

[0040] The present copolymer may or may not contain, in addition to the TFE units and PAVE units, units based on other monomers copolymerizable with TFE and PAVE. Other monomers include, for example, ethylene, vinylidene fluoride (VdF), hexafluoropropylene (HFP), CX 1 X 2 =CX 3 (CF2) n X 4 (In the formula, X 1 , X 2 , and X 3 each independently represents a hydrogen atom or a fluorine atom; X 4 represents a hydrogen atom, a fluorine atom, or a chlorine atom, and n represents an integer of 1 to 10. 2 (In the formula, Rf 2represents a perfluoroalkyl group having 1 to 5 carbon atoms. When the present copolymer contains units based on other monomers, the content of the units based on other monomers is preferably 5.0 mass% or less, more preferably 2.0 mass% or less, and even more preferably 1.0 mass% or less, based on the total monomer units contained in the present copolymer.

[0041] From the viewpoint of favorably exhibiting the properties of the TFE units and PAVE units and from the viewpoint of making the molded article less susceptible to deformation by compression or tension, the copolymer preferably contains only TFE units and PAVE units, without containing units derived from the other monomers described above. In this case, the total content of TFE units and PAVE units is 100.0% by mass of all monomer units contained in the copolymer.

[0042] The contents of TFE units, PAVE units, and units based on other monomers in this copolymer are as follows: 19 It can be measured by known methods such as F-NMR (nuclear magnetic resonance analysis).

[0043] The copolymer has a total number of specific functional groups (hereinafter also referred to as "specific functional groups") selected from the group consisting of -CF=CF2, -CF2H, -COF, -COOH, -COOCH3, -CONH2, and -CH2OH (hereinafter also referred to as "number of specific functional groups") that is greater than or equal to 10 main chain carbon atoms of the copolymer. 6 The number of specific functional groups is preferably 200 or less, more preferably 100 or less, even more preferably 50 or less, particularly preferably 10 or less, and extremely preferably 6 or less. By keeping the number of specific functional groups below the upper limit, decomposition from the terminal functional groups is suppressed, and the heat resistance of the molded product is likely to be improved. It is preferable that the number of specific functional groups is small, but it is also preferable that the number of specific functional groups is less than 10. 6 There may be one or more, two or more, or three or more per piece.

[0044] The specific functional group is a functional group present at the main chain terminal or side chain terminal of the copolymer, and a functional group present in the main chain or side chain. The specific functional group is introduced into the copolymer, for example, by a chain transfer agent or polymerization initiator used in the production of the copolymer. More specifically, for example, when an alcohol is used as a chain transfer agent or when a peroxide having a -CHOH structure is used as a polymerization initiator, -CHOH is introduced into the main chain terminal of the copolymer. The specific functional group can also be introduced into the side chain terminal of the copolymer by polymerizing a monomer having a functional group. Furthermore, if the number of functional groups in the copolymer having specific functional groups exceeds a predetermined range, the number of functional groups can be reduced by fluorinating the copolymer and converting the specific functional groups to -CF3 terminal groups. The number of functional groups in the copolymer can be adjusted by changing the conditions of the fluorination treatment (treatment time, etc.).

[0045] The type and number of functional groups in the copolymer can be identified and measured by infrared spectroscopy. Specifically, the number of functional groups is measured by the following method. First, the copolymer is molded by hot pressing at 330°C to prepare a film with a thickness of 0.25 to 0.30 mm. This film is analyzed by Fourier transform infrared spectroscopy (FT-IR) to obtain an infrared absorption spectrum of the copolymer. Separately, an infrared absorption spectrum (base spectrum) is obtained that is completely fluorinated and does not contain any specific functional groups, and a difference spectrum between the infrared absorption spectrum of the copolymer and the base spectrum is obtained. From the absorption peaks of the specific functional groups that appear in this difference spectrum, the number of functional groups in the copolymer with 10 main chain carbon atoms is determined according to the following formula (A): 6 Calculate the number of functional groups per molecule, N.

[0046] N=I×K / t (A) I: Absorbance K: Correction coefficient t: film thickness (mm)

[0047] The absorption frequency, molar absorption coefficient, and correction factor for specific functional groups are shown in Table 1. The molar absorption coefficient for a specific functional group is determined from FT-IR (Fourier transform infrared spectroscopy) measurement data of a low molecular weight model compound.

[0048] [Table 1]

[0049] In this copolymer, the absorption frequencies of -CH2CF2H, -CH2COF, -CH2COOH, -CH2COOCH3, and -CH2CONH2 are calculated by multiplying the absorption frequencies of -CF2H, -COF, -COOH (free and bonded), -COOCH3, and -CONH2 shown in the table by several tens of Kaiser (cm -1 For example, the number of -COFs is lower than the absorption frequency of 1883 cm due to -CF2COF. -1 The number of functional groups determined from the absorption peak of -CH2COF and the absorption frequency of 1840 cm -1 The number of functional groups is the sum of the number of functional groups determined from the absorption peaks of the compounds.

[0050] From the viewpoint of excellent mechanical strength of the molded article, the melting point of the present copolymer is preferably 298.0° C. or higher, more preferably 299.0° C. or higher, and even more preferably 300.0° C. or higher. From the viewpoint of excellent moldability of the present copolymer and excellent low-speed tear strength of the molded article, the melting point of the present copolymer is preferably 310.5° C. or lower, more preferably 310.0° C. or lower, and even more preferably 309.5° C. or lower. The melting point of the present copolymer can be adjusted to fall within the above range by lowering the polymerization temperature during production of the present copolymer. The melting point of the copolymer is the temperature corresponding to the endothermic peak when the copolymer is heated at a rate of 10°C / min in an air atmosphere using a differential scanning calorimeter.

[0051] Copolymers are not intended to be so-called elastomers. Elastomers are copolymers that do not have a melting point.

[0052] [Other ingredients] The composition of the present disclosure may or may not contain components other than the present copolymer. For example, the composition of the present disclosure may contain a resin other than the present copolymer, a heat stabilizer, an antioxidant, a colorant, an ultraviolet absorber, a filler, a crosslinking agent, a crosslinking aid, an organic peroxide, etc. When the composition of the present disclosure contains components other than the copolymer, the total content of such components is preferably 70 parts by mass or less, more preferably 50 parts by mass or less, even more preferably 10 parts by mass or less, particularly preferably 1 part by mass or less, and very preferably 0.1 parts by mass or less, per 100 parts by mass of the copolymer. The total content of components other than the copolymer may be 0.0000001 parts by mass or more, 0.0000005 parts by mass or less, or even 0.000001 parts by mass or more, per 100 parts by mass of the copolymer. From this perspective, the total content of components other than the copolymer may be 0.0000001 to 70 parts by mass, per 100 parts by mass of the copolymer.

[0053] In order to make the slope T a positive value, the composition of the present disclosure preferably does not contain PTFE. When PTFE is contained, the amount thereof is preferably 0.009 part by mass or less, and more preferably 0.008 part by mass or less, per 100 parts by mass of the present copolymer.

[0054] Although the form of the composition of the present disclosure is not particularly limited, the composition of the present disclosure is preferably a solid composition. A "solid composition" means a composition that is solid at 25°C.

[0055] [Method for producing the composition] The method for producing a composition of the present disclosure includes a step of using TFE and PAVE as raw materials, polymerizing them by a solution polymerization method, and producing a composition containing a copolymer containing TFE units and PAVE units (hereinafter also referred to as the "polymerization step"), wherein the TFE unit content is 93.0 to 98.0 mass% based on all monomer units of the copolymer, the PAVE unit content is 2.0 to 7.0 mass% based on all monomer units of the copolymer, the melt flow rate measured under conditions of a temperature of 372°C is 1.0 to 40.0 g / 10 min, and when 5 to 12 mol% of PAVE has been consumed during polymerization based on the amount of PAVE used at the start of polymerization, TFE is added in an amount of 15 to 65 mol% based on the total amount of PAVE and TFE used at the start of polymerization.

[0056] In a typical production method, all raw materials are used at the start of polymerization, but in the method for producing a composition of the present disclosure, TFE is added later during polymerization, thereby producing the composition of the present disclosure. That is, according to the method for producing a composition of the present disclosure, it is possible to produce a composition that contains a copolymer containing TFE units and PAVE units, in which the TFE unit content is 93.0 to 98.0 mass% based on the total monomer units of the copolymer, the PAVE unit content is 2.0 to 7.0 mass% based on the total monomer units of the copolymer, the MFR is 1.0 to 40.0 g / 10 min, the proportion A is 1% to 20%, and the slope T is a positive value.

[0057] During polymerization, the amount of PAVE consumed relative to the amount of PAVE used at the start of polymerization is determined by the following method. The polymerization is terminated when the amount of TFE continuously added after the start of polymerization reaches 160 g, and the resulting slurry is filtered to separate the polymerization medium, which is then dried at 100°C for 15 hours. The resulting white powder is then 19 The molar ratio of PAVE was calculated using an F-nuclear magnetic resonance spectrometer (Bruker Biospin's AVANCE-III-HD400). The amount of PAVE consumed can be confirmed from the relationship between the amount of PAVE used and the molar ratio.

[0058] If TFE is added when the PAVE consumption amount is 5 mol % or more, the proportion of TFE units in the copolymer produced after the addition of TFE can be relatively increased. If TFE is added when the PAVE consumption is below 12 mol%, the content of copolymers with a relatively high proportion of TFE units in the copolymer produced after the addition of TFE will not become too high, making it easier to control the composition of the copolymer produced through polymerization. From this viewpoint, the amount of PAVE consumed at the time of adding TFE is more preferably 5 to 12 mol %, and even more preferably 6 to 11 mol %.

[0059] By adding TFE at a predetermined time point during polymerization in an amount of 15 to 65 mol % relative to the total amount of PAVE and TFE used at the start of polymerization, a copolymer having a higher proportion of TFE units in the PAVE units and TFE units than the proportion of TFE units in the PAVE units and TFE units at the start of polymerization can be obtained in polymerization from the predetermined time point onwards. A copolymer with a high proportion of TFE units is not PTFE, but can be said to have a composition similar to PTFE. The composition obtained by the production method of the present disclosure contains PFA with a composition similar to that of PTFE, and therefore, a molded article with excellent surface smoothness can be obtained.

[0060] As described above, the copolymer contained in the composition obtained by the method for producing a composition of the present disclosure contains TFE units and PAVE units, and includes copolymers with a relatively small amount of TFE units and copolymers with a relatively large amount of TFE units in terms of the ratio of TFE units to PAVE units. Thus, when the copolymers are viewed individually, the proportions of TFE units differ, but when viewed as an aggregate, the content of TFE units is 93.0 to 98.0 mass% of the total monomer units of the copolymer, and the content of PAVE units is 2.0 to 7.0 mass% of the total monomer units of the copolymer.

[0061] Even when all the raw materials are used at the start of polymerization, the resulting copolymer usually has some degree of distribution in the ratio of each structural unit. In contrast, the method for producing the composition of the present disclosure provides a larger distribution by adding TFE later during polymerization, although measuring this distribution is difficult.

[0062] The amount of TFE to be added when 5 to 12 mol% of PAVE has been consumed is 15 to 65 mol%, preferably 16 to 60 mol%, and more preferably 17 to 60 mol%, of the total amount of PAVE and TFE used at the start of polymerization, from the viewpoint of making it easier to increase the content of TFE units in the copolymer obtained after the addition of TFE.

[0063] Furthermore, after the initiation of polymerization, TFE may be continuously added before PAVE is consumed in an amount of 5 to 12 mol % based on the amount of PAVE used at the initiation of polymerization. By continuously adding TFE after the initiation of polymerization, the pressure during polymerization can be maintained at the same level as the pressure at the initiation of polymerization.

[0064] Furthermore, TFE may be added in an amount of 15 to 65 mol % based on the total amount of PAVE and TFE used at the start of polymerization, and then TFE may be added continuously. By adding additional TFE and then continuously adding TFE, the pressure during the polymerization can be maintained at the same pressure as at the start of the polymerization.

[0065] In the polymerization step, in addition to the above-mentioned monomers (TFE, PAVE, and other monomers as required), a polymerization initiator, a polymerization medium, a chain transfer agent, an emulsifier, a pH adjuster, etc. can be used.

[0066] The polymerization initiator is preferably a radical polymerization initiator having a half-life of 10 hours at a temperature of 0 to 100°C, and more preferably a radical polymerization initiator having a temperature of 20 to 90°C. Specific examples of the polymerization initiator include various polymerization initiators exemplified in WO 2013 / 015202. One type of polymerization initiator may be used alone, or two or more types may be used in combination. The amount of the polymerization initiator used is preferably 0.01 to 0.9 parts by mass, more preferably 0.05 to 0.5 parts by mass, based on 100 parts by mass of the amount of the monomer used.

[0067] Examples of the polymerization medium include water, organic solvents, and mixed solvents of water and organic solvents. Examples of the organic solvent include fluorine-based solvents such as perfluorocarbons, hydrofluorocarbons, and hydrofluoroethers. Specific examples of the organic solvent include the polymerization media exemplified in WO 2013 / 015202. The polymerization medium is preferably a polymerization medium containing water. As the water, ultrapure water is more preferred.

[0068] In particular, from the viewpoint of the balance between viscosity and thermal conductivity, it is preferable that the polymerization medium contains a hydrofluoroether, that is, it is preferable that the polymerization be carried out in a liquid medium containing a hydrofluoroether.

[0069] Hydrofluoroethers include methoxynonafluorobutane (HFE-7100), 1,1-difluoroethyl-2,2,2-trifluoroethyl ether (HFE-365mf-c), 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether (HFE-347pc-f), 1,1-difluoroethyl-2,2,3,3,3-pentafluoropropyl ether (HFE-467sc-f), ethoxynonafluorobutane (HFE-569s1), 1,1,2,3,3,3-hexafluoropropyl-2,2,2-trifluoroethyl ether (HFE-449mec-f), and 1,1,2,2-tetrafluoroethyl-2,2,3,3,3-pentafluoropropyl ether (HFE-449 pc-f), 1,1-difluoroethyl-2,2,3,3-tetrafluoropropyl ether (HFE-476pcf-c), 1,1,2,3,3,3-hexafluoropropyl-2,2,3,3,3-pentafluoropropyl ether (HFE-54-11mec-f), 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (HFE-458pc-fc), 1,1,2,3,3,3-hexafluoropropyl-2,2,3,3-tetrafluoropropyl ether (HFE-55-10mec-fc), 3-methoxy-4-trifluoromethyl-1,1,1,2,2,3,4,5,5,5-decafluoropentane (CFCF(OCH)CF(CF)CF).

[0070] In particular, from the viewpoint of polymerization reactivity, the hydrofluoroether is preferably 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether.

[0071] From the viewpoint of easily obtaining a copolymer with a low metal element content, the water preferably has a metal element content of 2.0 mass ppm or less, more preferably 1.0 mass ppm or less, still more preferably 0.5 mass ppm or less, and particularly preferably 0.1 mass ppm or less. The metal element content is preferably 0 mass ppb or more. The method for achieving the above-mentioned metal element contents is not particularly limited, and examples thereof include a method for reducing the metal element content by filtering water through various filters. The content of metal elements in water can be measured by the absolute calibration curve method using ICP-MS. The electrical conductivity of water is preferably 1.00 μS / cm or less, more preferably 0.08 μS / cm or less. The lower limit is preferably 0 μS / cm or more. The magnitude of the electrical conductivity of water is related to the amount of metal elements in the water, and the greater the amount of metal elements, the greater the electrical conductivity of the water. The electrical conductivity of water can be measured by a known measurement method.

[0072] The polymerization medium may be used alone or in combination of two or more. As the polymerization medium, a mixed solvent of water and a fluorine-based solvent is preferred, and a mixed solvent of water and a perfluorocarbon is more preferred. From the viewpoints of suspension property and economy, the amount of the fluorine-based solvent used is preferably 10% by mass or more and less than 100% by mass based on the total mass of the mixed solvent. The amount of the polymerization medium used is preferably 3 times or more, more preferably 5 times or more, by mass ratio relative to the amount of the monomers used. The amount of the polymerization medium used is preferably 20 times or less, more preferably 17 times or less, by mass ratio relative to the amount of the monomers used. From this viewpoint, the amount of the polymerization medium used is preferably 3 to 20 times, more preferably 5 to 17 times, by mass ratio relative to the amount of the monomers used.

[0073] As the chain transfer agent, from the viewpoint of having a large chain transfer constant and requiring only a small amount to be added, alcohols such as methanol, ethanol, 2,2,2-trifluoroethanol, 2,2,3,3-tetrafluoropropanol, 1,1,1,3,3,3-hexafluoroisopropanol, and 2,2,3,3,3-pentafluoropropanol; hydrocarbons such as n-pentane, n-hexane, and cyclohexane; hydrofluorocarbons such as CF2H2; ketones such as acetone; mercaptans such as methyl mercaptan; esters such as methyl acetate and ethyl acetate; and ethers such as diethyl ether and methyl ethyl ether are preferred. Among them, from the viewpoint of a higher chain transfer constant and high stability of the terminal groups of the present copolymer, at least one selected from the group consisting of alcohols, hydrocarbons, and hydrofluorocarbons is preferred, at least one selected from the group consisting of alcohols and hydrocarbons is more preferred, and alcohols are even more preferred. As the alcohol, methanol or ethanol is preferred, and from the viewpoint of reactivity and easy availability, methanol is more preferred. One type of chain transfer agent may be used alone, or two or more types may be used in combination. The amount of the chain transfer agent used is preferably 0.001 times or more, more preferably 0.005 times or more, by mass ratio, relative to the amount of the monomer used. The amount of the chain transfer agent used is preferably 5 times or less, more preferably 4 times or less, by mass ratio, relative to the amount of the monomer used. From this viewpoint, the amount of the chain transfer agent used is preferably 0.001 to 5 times, more preferably 0.005 to 4 times, by mass ratio, relative to the amount of the monomer used.

[0074] As the compounds used in the polymerization (monomer components, polymerization initiators, chain transfer agents, emulsifiers, pH adjusters, etc., excluding aqueous media), it is preferable not to use compounds containing metal elements, from the viewpoint of easily obtaining a composition with a low content of metal elements.

[0075] The polymerization temperature is preferably 15 to 60° C., more preferably 20 to 58° C., and even more preferably 25 to 55° C. When the polymerization temperature is 15° C. or higher, the polymerizability can be excellent. When the polymerization temperature is 60° C. or lower, the melting point of the present copolymer can be improved. The polymerization pressure is preferably from 0.5 to 3.0 MPa, more preferably from 0.9 to 2.5 MPa. The polymerization time is preferably 1 to 12 hours.

[0076] When an aqueous dispersion containing the present copolymer is obtained by carrying out the polymerization step, the present copolymer can be recovered by coagulating the present copolymer contained in the aqueous dispersion, washing, and drying. When the present copolymer is obtained as a slurry by polymerization, the present copolymer can be recovered by removing the slurry from the reaction vessel, washing, and drying. By drying, the present copolymer can be recovered in powder form.

[0077] [Fluorination step] The method for producing the composition of the present disclosure may further include a step of fluorinating the copolymer obtained in the polymerization step (this step is also referred to as the "fluorination step"). The fluorination treatment can convert specific functional groups that the copolymer may have, such as -COOH, -COOCH3, -CH2OH, -COF, -CF=CF2, -CONH2, and -CF2H, to -CF3. This reduces the number of specific functional groups, making it easier to adjust the number of functional groups in the copolymer to within a predetermined range.

[0078] The fluorination treatment is carried out by contacting the unfluorinated copolymer with a fluorine-containing compound. The fluorine-containing compound may be a fluorine radical source that generates fluorine radicals under fluorination treatment conditions. Examples of the fluorine radical source include F2 gas, N2F2, and halogen fluorides (e.g., IF5 and ClF3).

[0079] The concentration of the fluorine radical source such as F2 gas may be 100% by volume. From the viewpoint of safety, it is preferable to use a mixed gas obtained by diluting the F2 gas with an inert gas so that the concentration is 5 to 50% by volume (preferably 15 to 30% by volume). Examples of the inert gas include nitrogen gas, helium gas, and argon gas, and from the viewpoint of economy, nitrogen gas is preferred.

[0080] The temperature during the fluorination treatment is preferably equal to or lower than the melting point of the copolymer, more preferably 20 to 240° C., and even more preferably 100 to 235° C. The fluorination treatment may be carried out by contacting the copolymer in a molten state with a fluorine-containing compound.

[0081] Specific methods for the fluorination treatment include, for example, placing a shelf on which the copolymer is placed in an oven, filling the oven with F gas or a mixed gas, and heating for a certain period of time. Another example is a method in which F gas or a mixed gas is passed through a flow column packed with copolymer pellets while heating the column. The treatment time for the fluorination treatment can be adjusted appropriately depending on the number of functional groups in the copolymer before the fluorination treatment, the desired number of functional groups, and the fluorination treatment method, and is, for example, 0.5 to 30 hours, preferably 1 to 24 hours.

[0082] [Molded body] The molded article of the present disclosure is a molded article of the composition of the present disclosure. The molded article of the present disclosure can be obtained by molding the composition of the present disclosure.

[0083] Specific examples of the molded article of the present disclosure include an injection molded article obtained by injection molding a composition, an extrusion molded article obtained by extrusion molding, a blow molded article obtained by blow molding, a transfer molded article obtained by transfer molding, a press molded article obtained by press molding, a rotational molded article obtained by rotational molding, and a coating film obtained by electrostatic coating. The molded article of the present invention is preferably a press molded article obtained by press molding. In addition, an injection molded article is also preferred because it can be obtained as an injection molded article with a beautiful appearance without corroding the mold used for molding.

[0084] The molded body of the present disclosure may be in the form of, for example, pellets or powder. The molded article of the present disclosure can be molded by a conventionally known method, for example, a method in which the composition is melted and extruded using a single-screw extruder, a twin-screw extruder, or a tandem extruder, and then cut into a predetermined length and molded into pellets. The extrusion temperature in melt extrusion varies depending on the melt viscosity of the composition and the production method, but is preferably 20 to 140°C higher than the melting point of the composition. The molded product can be cut by conventional methods such as strand cutting, hot cutting, underwater cutting, and sheet cutting. The resulting pellets may be heated to remove volatile components (degassing treatment). The resulting pellets may be treated by contacting them with hot water at 30 to 200°C, steam at 100 to 200°C, or hot air at 40 to 200°C.

[0085] Specific examples of the molded article of the present disclosure include nuts, bolts, joints, films, bottles, gaskets, wire coating materials, tubes, hoses, pipes, valves, sheets, seals, packing, tanks, rollers, containers, cocks, connectors, filter housings, filter cages, flow meters, pumps, wafer carriers, and wafer boxes.

[0086] The molded article of the present disclosure can be used for the following purposes. Fluid transfer components for food manufacturing equipment, such as food packaging films, lining materials for fluid transfer lines used in food manufacturing processes, packings, sealing materials, and sheets; chemical stoppers, packaging films, lining materials for fluid transfer lines used in chemical manufacturing processes, packings, sealing materials, and sheets; inner lining materials for chemical tanks and piping in chemical plants or semiconductor factories; fuel transfer components, such as O-rings, tubes, packings, valve core materials, hoses, and sealing materials used in automobile fuel systems and peripheral equipment, and hoses and sealing materials used in automobile automatic transmissions; carburetor flange gaskets, shaft seals, valve stem seals, sealing materials, and hoses used in automobile engines and peripheral equipment, as well as other automotive components, such as automobile brake hoses, air conditioner hoses, radiator hoses, and electrical wire coating materials; semiconductor manufacturing equipment, such as O-rings, tubes, packings, valve core materials, hoses, sealing materials, rolls, gaskets, diaphragms, and fittings. chemical liquid transport components for equipment; coating and ink components such as paint rolls, hoses, tubes, and ink containers for coating equipment; food and beverage transport components such as tubes, hoses, belts, packing, and joints, such as food and beverage tubes and food and beverage hoses, food packaging materials, and glass cooking equipment; waste liquid transport components such as tubes and hoses for transporting waste liquid; high-temperature liquid transport components such as tubes and hoses for transporting high-temperature liquids; steam piping components such as tubes and hoses for steam piping; anti-corrosion piping tapes, such as tapes wrapped around piping on ship decks, etc.; various coating materials, such as electric wire coating materials, optical fiber coating materials, and transparent surface coating materials and backing agents applied to the light-incident surface of photovoltaic elements in solar cells; sliding components, such as diaphragms and various packings for diaphragm pumps; agricultural films, fuel cell carrier films, and weather-resistant covers for various roofing materials and side walls; interior materials used in the construction field, and glass coating materials, such as non-flammable fire-resistant safety glass; and lining materials, such as laminated steel sheets, used in home appliances, etc.

[0087] In particular, the molded article of the present disclosure can be suitably used as a sheet, a tube, a joint, a nut, a sheet, a tank, a wire covering material, or a compressed member.

[0088] The compressed member is a member used in a compressed and deformed state, and the size and shape of the compressed member are appropriately set depending on the application. The shape of the compressed member may be, for example, an annular shape. The compressed member may also have a circular, oval, or rectangular shape with rounded corners in a plan view, and may have a through hole in the center.

[0089] The compressed member can be used as a piping member for transporting a fluid. The compressed member can also be used as a member for constituting a nonaqueous electrolyte battery, and is particularly suitable as a member used in a state in contact with the nonaqueous electrolyte in the nonaqueous electrolyte battery.

[0090] The compressible member can also be suitably used as a sealing member such as a sealing gasket and sealing packing, and an insulating member such as an insulating gasket and insulating packing. A sealing member is a member used to prevent leakage of liquid or gas or intrusion of liquid or gas from the outside. An insulating member is a member used for electrical insulation. The compressible member may be a member used for both sealing and insulating purposes.

[0091] [Coated wire] The coated electric wire of the present disclosure includes a conductor and a coating layer disposed on the surface of the conductor and containing the composition of the present disclosure. The coating layer is preferably a layer obtained by molding the composition of the present disclosure.

[0092] The coated electric wire is suitable for LAN cables (Ethernet Cables), high-frequency transmission cables, flat cables, heat-resistant cables, etc. In particular, the coated electric wire is suitable for transmission cables such as LAN cables (Ethernet Cables) and high-frequency transmission cables.

[0093] Examples of the material of the conductor include metals such as copper, aluminum, etc. The diameter of the conductor is, for example, 0.02 to 3 mm.

[0094] Specific examples of conductors include AWG (American Wire Gauge)-46 (solid copper wire with a diameter of 40 micrometers), AWG-26 (solid copper wire with a diameter of 404 micrometers), AWG-24 (solid copper wire with a diameter of 510 micrometers), and AWG-22 (solid copper wire with a diameter of 635 micrometers).

[0095] The thickness of the coating layer is, for example, 0.1 to 3.0 mm.

[0096] An example of a high-frequency transmission cable is a coaxial cable. A coaxial cable generally has a structure in which an inner conductor, an insulating coating layer, an outer conductor layer, and a protective coating layer are layered in this order from the core to the outer periphery. A molded article containing the copolymer of the present disclosure can be suitably used as an insulating coating layer containing the copolymer. The thickness of each layer in the above structure is not particularly limited, but typically the inner conductor has a diameter of about 0.1 to 3 mm, the insulating coating layer has a thickness of about 0.3 to 3 mm, the outer conductor layer has a thickness of about 0.5 to 10 mm, and the protective coating layer has a thickness of about 0.5 to 2 mm.

[0097] The coated wire may have another layer between the conductor and the coating layer, or may have a further layer outside the coating layer.

[0098] The coated wire can be produced, for example, by extruding the composition of the present disclosure in a molten state onto a conductor to form a coating layer. [Example]

[0099] Next, embodiments of the present disclosure will be described in detail using examples, but the embodiments of the present disclosure are not limited to these examples. In the following examples, Examples 1 to 5 are working examples, and Examples 6 and 7 are comparative examples.

[0100] (Abbreviation of each monomer unit) PTFE: Polytetrafluoroethylene TFE: Tetrafluoroethylene PPVE: Perfluoro(propyl vinyl ether) AE-3000: 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether

[0101] (Content of each monomer unit) The content (mass%) of each unit contained in the composition obtained in each example is: 19 The molar ratio was calculated using an F-nuclear magnetic resonance spectrometer (AVANCE-III-HD400 manufactured by Bruker Biospin), and the calculated molar ratio was converted into a mass ratio from the chemical structural formula of each unit.

[0102] (MFR (Melt Flow Rate)) For the compositions obtained in each example, a melt flow tester (Shimadzu Corporation, "CFT-500EX") was used to measure the mass (g) of molding material flowing out of an orifice with a diameter of 2.095 mm and a length of 8 mm in 10 minutes under conditions of a temperature of 372°C and a load of 5 kg in accordance with ASTM D1238, and this was taken as MFR (g / 10 min).

[0103] (Number of functional groups) The fluorination-treated composition obtained in each example was hot-pressed at 330°C using a hydraulic press ("SA-301" manufactured by Tester Sangyo Co., Ltd.) to produce a sample film with a thickness of 0.25 to 0.30 mm. This sample film was scanned 40 times using a Fourier transform infrared spectrometer ("FT-IR" manufactured by ThermoScientific "Nicolet iS5") to obtain an infrared absorption spectrum. Next, the above composition was subjected to a fluorination treatment described later for a long time, and each base sample that was completely fluorinated and had no functional groups was separately prepared, and a base film was produced from each base sample in the same manner as above. The base film was analyzed by the above method to obtain an infrared absorption spectrum (base spectrum), and a difference spectrum between the infrared absorption spectrum of the above sample film and the base spectrum of the base film was obtained. From the absorption peaks of the functional groups appearing in this difference spectrum, the main chain carbon number of the fluorine-containing resin contained in the sample film was calculated according to the following formula (A): 6 The number of functional groups per molecule, N, was calculated. The correction coefficients used are as shown in Table 1 above. N=I×K / t (A) I: Absorbance K: Correction coefficient t: film thickness (mm)

[0104] (Melting Point) The melting point (°C) of the composition was determined using a differential scanning calorimeter (NETZSCH "DSC204F1 Phoenix") by heating 10-30 mg of the fluorination-treated composition obtained in each example in an air atmosphere from 200°C to 350°C at 10°C / min, subsequently cooling from 350°C to 200°C at 10°C / min, and again heating from 200°C to 350°C at 10°C / min, from which the maximum endothermic peak was measured.

[0105] [Example 1] (Preparation of Composition 1) A 1.3 L polymerization vessel equipped with a stirrer was degassed, and then 625 g of CF3CH2OCF2CF2H (AE-3000, product name, manufactured by AGC Corporation), 417 g of water, 91.3 g of PPVE (343.9 mmol, the amount of PPVE used at the start of polymerization), and 22.6 g of methanol were charged into the polymerization vessel. The temperature inside the polymerization vessel was then raised to 50 °C (polymerization temperature), and 140 g of TFE (1405.2 mmol, the amount of TFE used at the start of polymerization) was charged, and the pressure inside the polymerization vessel was increased to 1.30 MPa (gauge pressure). 2 mL of a 0.06 wt% AE-3000 solution of heptafluorobutyroyl peroxide was charged as a polymerization initiator solution to initiate polymerization, and the above polymerization initiator solution was continuously added thereafter. TFE was continuously charged to maintain the pressure during polymerization equal to the pressure at the start of polymerization. 43 mL of the polymerization initiator solution was added, and 160 g of TFE was continuously charged. When 7.3 mol % of the PPVE used at the start of polymerization was consumed, 28 g of TFE was added. This 28 g of TFE corresponds to 18.5 mol % of the total amount of PPVE and TFE used at the start of polymerization. The pressure in the polymerization vessel rose to 1.52 MPa (gauge pressure). TFE was continuously added to maintain the pressure during polymerization at the same level as the pressure at the start of polymerization. After 2 mL of the polymerization initiator solution was added and 10 g of TFE was continuously charged, the temperature in the polymerization vessel was lowered to 23°C and the vessel was purged until the pressure reached 1 atm. The polymerization time was 300 minutes.

[0106] The resulting slurry was filtered to separate the polymerization medium, and then dried at 100°C for 15 hours to obtain an untreated copolymer, whose composition was TFE unit / PPVE unit = 96.2 / 3.8 (mass%).

[0107] The untreated copolymer was then subjected to a tray-type fluorination treatment in the following manner. Untreated Composition 1 placed in a dedicated tray was placed in a box-type reaction oven, which was then sealed and evacuated. An F / N mixed gas, diluted with N to a concentration of 20% by volume, was then introduced into the oven, filling the oven with the mixed gas. The pressure inside the oven was maintained at atmospheric pressure (1 atm), and the temperature was maintained at 230°C. The reaction was allowed to proceed for 120 minutes from the start of the introduction of the mixed gas. After the reaction was completed, heating was stopped and the F2 / N2 mixed gas in the oven was replaced with N2 gas. Composition 1 was removed from the oven and the number of functional groups was calculated according to the procedure described above. The number was found to be less than 6. The MFR of Composition 1 was 13.5 g / 10 min. The composition of the copolymer contained in Composition 1 was the same as that of the untreated copolymer.

[0108] [Example 2] (Preparation of Composition 2) The amount of PPVE initially charged to the polymerization vessel was changed to 56.0 g, and the amount of methanol was changed to 20.2 g. During the polymerization, 28.8 g of TFE was added when 7.2 mol% of PPVE had been consumed relative to the amount of PPVE used at the start of polymerization. This amount of TFE (28.8 g) corresponds to 20.3 mol% of the total amount of PPVE and TFE used at the start of polymerization. The procedure was the same as in Example 1, except that 10.0 g of TFE was continuously added after the additional TFE addition to terminate the polymerization. A copolymer with a TFE unit / PPVE unit composition of 97.5 / 2.5 (mass%) was obtained. The polymerization time was 280 minutes. Subsequently, the untreated copolymer was fluorinated in the same manner as in Example 1 to produce Composition 2, which had an MFR of 14.2 g / 10 min and less than 6 functional groups.

[0109] [Example 3] (Preparation of Composition 3) The amounts of PPVE, methanol, and TFE initially charged to the polymerization vessel were changed to 87.9 g, 16.8 g, and 99.2 g, respectively. During the polymerization, 65.1 g of TFE was added when 10.3 mol% of PPVE had been consumed relative to the amount of PPVE used at the start of polymerization. This amount of TFE corresponded to 55.1 mol% of the total amount of PPVE and TFE used at the start of polymerization. The procedure was the same as in Example 1, except that 4.0 g of TFE was continuously added after the additional TFE addition to terminate the polymerization. A copolymer with a TFE unit / PPVE unit composition of 94.3 / 5.7 (mass%) was obtained. The polymerization time was 370 minutes. Subsequently, the untreated copolymer was fluorinated in the same manner as in Example 1 to produce Composition 3, which had an MFR of 14.1 g / 10 min and less than 6 functional groups.

[0110] [Example 4] (Preparation of Composition 4) The amounts of AE-3000, water, PPVE, methanol, and TFE initially charged to the polymerization vessel were changed to 846.1 g, 270.0 g, 115.7 g, 7.5 g, and 186.2 g, respectively. During the polymerization, 48.4 g of TFE was added when 5.4 mol% of PPVE had been consumed relative to the amount of PPVE used at the start of polymerization. This amount of TFE corresponded to 23.0 mol% of the total amount of PPVE and TFE used at the start of polymerization. The procedure was the same as in Example 1, except that 7.7 g of TFE was continuously added after the additional TFE addition to terminate the polymerization. A copolymer with a TFE unit / PPVE unit composition of 96.5 / 3.5 (mass%) was obtained. The polymerization time was 260 minutes. Subsequently, the untreated copolymer was fluorinated in the same manner as in Example 1 to produce Composition 4, which had an MFR of 2.4 g / 10 min and less than 6 functional groups.

[0111] [Example 5] (Preparation of Composition 5) The amounts of AE-3000, water, PPVE, methanol, and TFE initially charged to the polymerization vessel were changed to 841.9 g, 272.5 g, 119.6 g, 5.2 g, and 126.7 g, respectively. During the polymerization, 97.5 g of TFE was added when 8.0 mol% of PPVE had been consumed relative to the amount of PPVE used at the start of polymerization. This amount of TFE corresponds to 61.5 mol% of the total amount of PPVE and TFE used at the start of polymerization. The procedure was the same as in Example 1, except that 5.4 g of TFE was continuously added after the additional TFE addition to terminate the polymerization. A copolymer with a TFE unit / PPVE unit composition of 94.1 / 5.9 (mass%) was obtained. The polymerization time was 290 minutes. Subsequently, the untreated copolymer was fluorinated in the same manner as in Example 1 to produce Composition 5, which had an MFR of 2.1 g / 10 min and less than 6 functional groups.

[0112] [Example 6] (Preparation of Composition 6) A copolymer having a composition of TFE unit / PPVE unit = 95.9 / 4.1 (mass%) was obtained in the same manner as in Example 1, except that no additional TFE was added. The polymerization time was 260 minutes. Subsequently, the untreated copolymer was fluorinated in the same manner as in Example 1 to prepare Composition 6 having an MFR of 13.9 g / 10 min and less than 6 functional groups.

[0113] [Example 7] (Preparation of Composition 7) The amount of AE-3000 initially charged into the polymerization vessel was changed to 843.9 g, the amount of water to 270.0 g, the amount of PPVE to 115.8 g, the amount of methanol to 7.9 g, and the amount of TFE to 186.0 g, and no additional TFE was added. The procedure was the same as in Example 1, except that a copolymer with a composition of TFE units / PPVE units = 96.5 / 3.5 (mass%) was obtained. The polymerization time was 230 minutes. Subsequently, the untreated copolymer was fluorinated in the same manner as in Example 1 to produce a copolymer with an MFR of 1.9 g / 10 min and less than 6 functional groups.

[0114] Next, for 100 parts of the copolymer after fluorination treatment, a fluorine-containing copolymer having an average particle size of 500 μm and a specific gravity of 2.16 g / cm 3The mixture was mixed in a vial and mixed at 25°C for 15 hours using a roller shaker (manufactured by IKA, device name "Roller 6 basic") to prepare Composition 7. The MFR of Composition 7 was 1.9 g / 10 min.

[0115] (Thermal property evaluation) -Heat of fusion- Using a differential scanning calorimeter (NETZSCH "DSC204F1 Phoenix"), the composition obtained in each example was heated from 200°C to 350°C at 10°C / min in an air atmosphere. Subsequently, it was cooled from 350°C to 200°C at 10°C / min. The composition was again heated from 200°C to 350°C at 10°C / min, and the peak area determined by connecting the points where the melting curve departs from the baseline and returns to the baseline around the melting peak of the melting curve was taken as the heat of fusion.

[0116] -Percentage A- The peak area determined from the curve from 315°C to 330°C and the straight line was calculated, and the proportion A of the peak area representing the heat of fusion was calculated.

[0117] -Tilt T- The slope T of the line connecting the heat flow at 315°C and the heat flow at 320°C in the melting curve was calculated.

[0118] (synovial fluid evaluation) -Ultrapure water contact angle- The compositions obtained in each example were hot-pressed at 330°C using a hydraulic press ("SA-301" manufactured by Tester Sangyo Co., Ltd.) to produce sample films measuring 5 cm in length, 5 cm in width, and 1.0 mm in thickness. A contact angle meter ("SA-Co1" manufactured by Kyowa Interface Science Co., Ltd.) was used to measure the contact angle of an arbitrary location on the sample film by dropping approximately 2 μL of ultrapure water (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) onto the sample film in a horizontally fixed position at 25°C. This was measured at five arbitrary points on the sample film, and the arithmetic mean value was calculated.

[0119] -Ultra-pure water fall angle- Using the contact angle meter, approximately 20 μL of ultrapure water was dropped onto the sample film and tilted from 0° to 90° relative to the horizontal plane at a rate of 1° / sec to measure the tilt angle at which the drop began to slide downward, i.e., the sliding angle. This was measured at five random points on the sample film, and the arithmetic average was calculated.

[0120] - Falling speed of ultrapure water - Using the contact angle meter, the sample film was tilted 50° from the horizontal plane, and approximately 20 μL of ultrapure water was dropped onto it. The maximum movement speed within the observation area after the droplet began to slide downward was measured and used as the sliding speed. This was measured at any five points on the sample film, and the arithmetic average value was calculated.

[0121] - Ultrapure water fall stability - The above-mentioned falling speed was measured at five random points on the sample film, and the slope of the movement speed versus the distance traveled by the droplet was determined during observation. The falling stability was evaluated based on the following criteria. If the slope of the movement speed versus the distance traveled by the droplet was always positive, it indicated that the droplet was falling stably without any decrease in its movement speed.

[0122] A: At any five measurement points, the slope of the droplet's velocity versus distance traveled is always positive. B: At one of any five measurement points, there is a point where the gradient of the droplet's movement speed relative to the movement distance is negative. C: At two or more of the five arbitrary measurement points, the gradient of the droplet movement speed with respect to the movement distance is negative.

[0123] The measurement results and evaluation results are shown in Table 2. In Table 2, when the composition contained PTFE, it was marked "Y", and when the composition did not contain PTFE, it was marked "N".

[0124] [Table 2]

[0125] As shown in Table 2, it was found that in Examples 1 to 5, the surface smoothness of the molded body was superior to that of Examples 6 and 7.

[0126] In Examples 1 to 5, the contact angle of ultrapure water exceeds 110°, which is at the same level as known PFA, and therefore the water repellency is comparable to that of PFA. The falling angle of ultrapure water is small when the ratio A is 1% or more. When the ratio A is 1% or more, the diameter of the spherulites generated in the molded product becomes small, which is thought to improve the smoothness of the molded product surface. This reduces the fine irregularities on the molded product surface, allowing ultrapure water droplets to fall even at a small angle. The falling speed of ultrapure water is high when the ratio A is 1% or more. The mechanism of action is the same as that of the falling angle of ultrapure water, allowing the ultrapure water droplets to fall quickly from the surface of the molded product. The dropping stability of ultrapure water is high when the ratio A is 1% or more and the slope T is always positive. When the slope T is always positive, the diameter distribution of the spherulites generated in the molded product is small, and it is thought that the smoothness of the molded product surface is less likely to be uneven. This reduces the size distribution of the fine irregularities on the molded product surface, allowing the ultrapure water droplets to drop quickly and reproducibly from the molded product surface.

Claims

1. A composition comprising a copolymer containing tetrafluoroethylene-based structural units and perfluoro(alkyl vinyl ether)-based structural units, the content of the structural units based on tetrafluoroethylene is 93.0 to 98.0% by mass based on all monomer units of the copolymer, the content of the structural units based on the perfluoro(alkyl vinyl ether) is 2.0 to 7.0 mass% based on all monomer units of the copolymer, a melt flow rate measured at a temperature of 372°C of 1.0 to 40.0 g / 10 min; In a melting curve observed by heating the composition from 200°C to 350°C at a rate of 10°C / min using a differential scanning calorimeter, the peak area, which indicates the heat of fusion, is determined by drawing a straight line between the points before and after the melting peak where the melting curve departs from the baseline and the points where the melting curve returns to the baseline. The peak area, which is determined by the curve from 315°C to 330°C in the melting curve and the straight line, accounts for 1 to 20% of the peak area, and the slope of the straight line connecting the heat flow at 315°C and the heat flow at 320°C is a positive value. composition.

2. The composition of claim 1 , wherein the perfluoro(alkyl vinyl ether)-based building blocks include perfluoro(propyl vinyl ether)-based building blocks.

3. 2. The composition according to claim 1, wherein the composition has a melt flow rate of 1.0 to 19.0 g / 10 min measured at a temperature of 372°C.

4. The copolymer has a main chain carbon number of 10 ６ Per piece, -CF = CF ２ , -CF ２ H, -COF, -COOH, -COOCH ３ , -CONH ２ , and -CH ２ 2. The composition of claim 1, wherein the total number of functional groups selected from the group consisting of OH is 50 or less.

5. The composition according to claim 1, wherein the proportion A is 5 to 20%.

6. A molded article of the composition according to any one of claims 1 to 5.

7. The molded article according to claim 6, which is a tube, a joint, a sheet, a nut, a tank, an electric wire coating material, or a compressed member.

8. A coated wire comprising a conductor and a coating layer disposed on a surface of the conductor and comprising the composition according to any one of claims 1 to 5.

9. The method includes using tetrafluoroethylene and perfluoro(alkyl vinyl ether) as raw materials, polymerizing them by a solution polymerization method, and producing a composition containing a copolymer containing structural units based on tetrafluoroethylene and structural units based on perfluoro(alkyl vinyl ether), the content of the structural units based on tetrafluoroethylene is 93.0 to 98.0% by mass based on all monomer units of the copolymer, the content of the structural units based on the perfluoro(alkyl vinyl ether) is 2.0 to 7.0 mass% based on all monomer units of the copolymer, a melt flow rate measured at a temperature of 372°C of 1.0 to 40.0 g / 10 min; a method for producing a composition, wherein, during the polymerization, when 5 to 12 mol % of the perfluoro(alkyl vinyl ether) has been consumed relative to the amount of the perfluoro(alkyl vinyl ether) used at the start of the polymerization, 15 to 65 mol % of the tetrafluoroethylene is added relative to the total amount of the perfluoro(alkyl vinyl ether) and the tetrafluoroethylene used at the start of the polymerization.

10. The method for producing a composition according to claim 9, wherein the polymerization is carried out in a liquid medium comprising a hydrofluoroether.

11. The method for producing a composition according to claim 10, wherein the hydrofluoroether is 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether.

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