Fluororesin aqueous dispersion production method, fluororesin, and low molecular weight polytetrafluoroethylene

Abstract

Provided is a fluororesin aqueous dispersion production method comprising (1) preparing an aqueous solution containing a water-soluble fluoropolymer by performing first polymerization of a fluoromonomer in the presence of an aqueous medium and a polymerization initiator and substantially in the absence of a fluorine-containing surfactant, and (2) preparing an aqueous dispersion containing a fluororesin by performing second polymerization of the fluoromonomer in the presence of the aqueous solution. The contained amount of the water-soluble fluoropolymer in the aqueous solution is more than 0 mass% to less than 1.0 mass% with respect to the mass of the aqueous solution. The contained amount of the fluororesin in the aqueous dispersion is not less than 15 mass% with respect to the mass of the aqueous dispersion. The polymerization rate of the first polymerization is not more than 3.0 g / (hr·L). Substantially in the absence of a fluorine-free anionic surfactant, the second polymerization is performed until the contained amount of the fluororesin in the aqueous dispersion reaches 10 mass% with respect to the mass of the aqueous dispersion from the start of the second polymerization.

Description

Method for producing an aqueous dispersion of fluororesin, fluororesin and low molecular weight polytetrafluoroethylene

[0001] This disclosure relates to a method for producing an aqueous dispersion of fluororesin, fluororesin, and low molecular weight polytetrafluoroethylene.

[0002] Patent Document 1 describes a method for polymerizing fluoromonomers in a polymerization reactor to form a dispersion of fluoropolymer particles in an aqueous medium, wherein the method includes an initial period and a stabilization period thereafter, wherein the initial period includes the step of preparing an initial dispersion of fluoropolymer particles in the aqueous medium in the polymerization reactor, and the stabilization period includes the step of polymerizing fluoromonomers in the polymerization reactor and the step of adding a hydrocarbon-containing surfactant to the polymerization reactor, wherein no fluorine-based surfactant is added during the stabilization period.

[0003] International Publication No. 2012 / 064841

[0004] The object of this disclosure is to provide a method for producing an aqueous dispersion of fluororesin that can be manufactured without using a fluorine-containing surfactant, while suppressing the adhesion of the generated polymer to the reactor.

[0005] The present disclosure provides a method for producing an aqueous dispersion of a fluororesin, comprising: (1) preparing an aqueous solution containing a water-soluble fluoropolymer by performing a first polymerization of a fluoromonomer in the presence of an aqueous medium and a polymerization initiator, substantially in the absence of a fluorine-containing surfactant; and (2) preparing an aqueous dispersion containing a fluororesin by performing a second polymerization of a fluoromonomer in the presence of the aqueous solution, substantially in the absence of a fluorine-containing surfactant, wherein the content of the water-soluble fluoropolymer in the aqueous solution is greater than 0% by mass and less than 1.0% by mass relative to the mass of the aqueous solution; the content of the fluororesin in the aqueous dispersion is 15% by mass or more relative to the mass of the aqueous dispersion; the polymerization rate of the first polymerization is 3.0 g / (hr·L) or less; and the second polymerization is performed substantially in the absence of a fluorine-free anionic surfactant from the start of the second polymerization until the content of the fluororesin in the aqueous dispersion reaches 10% by mass relative to the mass of the aqueous dispersion.

[0006] According to this disclosure, it is possible to provide a method for producing an aqueous dispersion of fluororesin that can be manufactured without using a fluorine-containing surfactant, while suppressing the adhesion of the generated polymer to the reactor.

[0007] Before describing this disclosure in detail, we define or explain some of the terms used in this disclosure.

[0008] In this disclosure, fluororesin is a partially crystalline fluoropolymer and is a fluoroplastic. Fluororesin has a melting point and is thermoplastic, but may be melt-processable or non-melt-processable.

[0009] In this disclosure, melt processability means that the polymer can be melted and processed using conventional processing equipment such as extruders and injection molding machines. Therefore, melt processable fluororesins typically have a melt flow rate of 0.01 to 500 g / 10 min, as measured by the measurement method described later.

[0010] In this disclosure, polytetrafluoroethylene [PTFE] is preferably a fluoropolymer in which the content of tetrafluoroethylene units relative to the total polymerization units is 99 mol% or more.

[0011] In this disclosure, the fluororesin (excluding polytetrafluoroethylene) is preferably a fluoropolymer in which the tetrafluoroethylene content relative to the total polymerization units is less than 99 mol%.

[0012] In this disclosure, the content of each monomer constituting the fluoropolymer can be calculated by appropriately combining NMR, FT-IR, elemental analysis, and X-ray fluorescence analysis depending on the type of monomer.

[0013] In this disclosure, "organic group" means a group containing one or more carbon atoms, or a group formed by removing one hydrogen atom from an organic compound. The organic group is preferably an alkyl group which may have one or more substituents.

[0014] In this disclosure, the range represented by an endpoint includes all numerical values ​​that fall within that range (for example, 1 to 10 includes 1.4, 1.9, 2.33, 5.75, 9.98, etc.).

[0015] In this disclosure, the phrase "at least one" includes all numbers one or more (for example, at least two, at least four, at least six, at least eight, at least ten, at least 25, at least 50, at least 100, etc.).

[0016] The following describes specific embodiments of this disclosure in detail, but this disclosure is not limited to the embodiments described below.

[0017] 1. Manufacturing Method This disclosure provides a method for producing an aqueous dispersion of a fluororesin, comprising: (1) preparing an aqueous solution containing a water-soluble fluoropolymer by performing a first polymerization of a fluoromonomer in the presence of an aqueous medium and a polymerization initiator, substantially in the absence of a fluorine-containing surfactant; and (2) preparing an aqueous dispersion containing a fluororesin by performing a second polymerization of a fluoromonomer in the presence of the aqueous solution, substantially in the absence of a fluorine-containing surfactant, wherein the content of the water-soluble fluoropolymer in the aqueous solution is greater than 0% by mass and less than 1.0% by mass with respect to the mass of the aqueous solution; the content of the fluororesin in the aqueous dispersion is 15% by mass or more with respect to the mass of the aqueous dispersion; the polymerization rate of the first polymerization is 3.0 g / (hr·L) or less; and the second polymerization is performed substantially in the absence of a fluorine-free anionic surfactant from the start of the second polymerization until the content of the fluororesin in the aqueous dispersion reaches 10% by mass with respect to the mass of the aqueous dispersion (hereinafter sometimes referred to as "the first manufacturing method of this disclosure").

[0018] Furthermore, this disclosure provides a method for producing an aqueous dispersion of fluororesin, comprising: (1) preparing an aqueous solution containing a water-soluble fluoropolymer by performing a first polymerization of a fluoromonomer in the presence of an aqueous medium and a polymerization initiator, substantially in the absence of a fluorine-containing surfactant; and (2) preparing an aqueous dispersion containing a fluororesin by performing a second polymerization of a fluoromonomer in the presence of the aqueous solution, substantially in the absence of a fluorine-containing surfactant, wherein the content of the water-soluble fluoropolymer in the aqueous solution is greater than 0% by mass and less than 1.0% by mass relative to the mass of the aqueous solution; the content of the fluororesin in the aqueous dispersion is 15% by mass or more relative to the mass of the aqueous dispersion; and the ratio of radical generation (B / A) calculated by the following formula is 0.7 or less (hereinafter referred to as "the second production method of this disclosure"). The ratio of radical generation (B / A) = B / A A: Radical generation per gram of aqueous medium per minute from the initial addition of the polymerization initiator for the first polymerization (A) (mol / (g・min)) B: Radical generation per gram of aqueous medium per minute from the start of the second polymerization (B) (mol / (g・min))

[0019] Furthermore, this disclosure provides a method for producing an aqueous dispersion of a fluororesin, comprising: (1) preparing an aqueous solution containing a water-soluble fluoropolymer by performing a first polymerization of a fluoromonomer in the presence of an aqueous medium and a polymerization initiator, substantially in the absence of a fluorine-containing surfactant; and (2) preparing an aqueous dispersion containing a fluororesin by performing a second polymerization of a fluoromonomer in the presence of the aqueous solution, substantially in the absence of a fluorine-containing surfactant, wherein the content of the water-soluble fluoropolymer in the aqueous solution is greater than 0% by mass and less than 1.0% by mass with respect to the mass of the aqueous solution; the content of the fluororesin in the aqueous dispersion is 15% by mass or more with respect to the mass of the aqueous dispersion; the polymerization initiator present in the first polymerization is a thermal decomposition type radical polymerization initiator, the first polymerization is started by adding the polymerization initiator, and the first polymerization continues until 90% by mass or more of the initially added polymerization initiator is decomposed; and the melting point of the water-soluble fluoropolymer is 250 to 330°C, or the glass transition temperature of the water-soluble fluoropolymer is 10°C or less. This is a manufacturing method in which the second polymerization is carried out in substantially the absence of a fluorine-free anionic surfactant from the start of the second polymerization until the content of the fluororesin in the aqueous dispersion reaches 10% by mass relative to the mass of the aqueous dispersion (hereinafter sometimes referred to as "the third manufacturing method of this disclosure").

[0020] In the first to third manufacturing methods of this disclosure, a fluororesin aqueous dispersion containing a fluororesin is produced by carrying out a first polymerization and a second polymerization.

[0021] According to the manufacturing method of this disclosure, a fluororesin can be produced using a previously unknown method, without the use of a fluorine-containing surfactant, while suppressing the adhesion of the generated polymer to the reactor.

[0022] 1-1. First manufacturing method In the first manufacturing method of the present disclosure, (1) in the absence of a substantially fluorine-containing surfactant, in the presence of an aqueous medium and a polymerization initiator, the first polymerization of a fluoromonomer is carried out to prepare an aqueous solution containing a water-soluble fluoropolymer, and (2) in the absence of a substantially fluorine-containing surfactant, in the presence of the aqueous solution, the second polymerization of a fluoromonomer is carried out to prepare an aqueous dispersion containing a fluororesin.

[0023] In the first manufacturing method of the present disclosure, in the first polymerization, a water-soluble fluoropolymer is produced, and in the second polymerization, a water-insoluble fluororesin is produced. In one embodiment, in the second polymerization, the water-soluble fluoropolymer and the fluoromonomer molecules react, and the polymer chains are extended to produce a water-insoluble fluororesin. When the content of the fluororesin in the aqueous dispersion reaches the target amount, the growth radicals can be deactivated to stop the polymerization reaction.

[0024] In the present disclosure, the water-soluble fluoropolymer refers to a fluoropolymer having a property that the particle size cannot be measured by the dynamic light scattering method (DLS). The water-soluble fluoropolymer preferably cannot measure the particle size even when contained in an aqueous solution at a content of 0.10% by mass. More preferably, the water-soluble fluoropolymer cannot measure the particle size even when contained in an aqueous solution at a content of 0.12% by mass, and still more preferably 0.15% by mass. On the other hand, since the fluororesin contained in the aqueous dispersion is water-insoluble, the particle size can be measured by the dynamic light scattering method (DLS).

[0025] In the first manufacturing method of the present disclosure, the first polymerization is carried out so that the content of the water-soluble fluoropolymer in the aqueous solution is more than 0% by mass and less than 1.0% by mass, preferably 0.05 to 0.80% by mass, based on the mass of the aqueous solution.

[0026] In the present disclosure, the content of the water-soluble fluoropolymer in the aqueous solution is a value obtained by drying 1 g of the aqueous solution in a blower dryer at 150 ° C. for 60 minutes and expressing the ratio of the mass of the heat residue to the mass of the aqueous solution (1 g) as a percentage.

[0027] In the first manufacturing method of this disclosure, the polymerization rate of the first polymerization is 3.0 g / (hr·L) or less. The polymerization rate is the amount of water-soluble fluoropolymer or fluororesin produced per hour per liter of aqueous medium. The polymerization rate of the first polymerization is preferably 2.0 g / (hr·L) or less, more preferably 1.5 g / (hr·L) or less, and the lower limit is not particularly limited, but may be 0.03 g / (hr·L) or more, 0.05 g / (hr·L) or more, or 0.15 g / (hr·L) or more. By adjusting the polymerization rate of the first polymerization within the above range, an aqueous dispersion containing fluororesin can be produced without using a fluorine-containing surfactant, while suppressing the adhesion of the produced polymer to the reactor. The polymerization rate of the first polymerization can be adjusted by adjusting the amount of polymerization initiator added, the polymerization temperature, and the number of stirs during polymerization.

[0028] The first polymerization is preferably carried out in the presence of either or both of the chain transfer agent and the nucleating agent, or in the absence of both the chain transfer agent and the nucleating agent. In this case, the total amount of the chain transfer agent and the nucleating agent is preferably 5.0 mol% or less, more preferably 4.0 mol%, even more preferably 3.0 mol% or less, and still more preferably 1.0 mol% or less, relative to the total amount of monomer, chain transfer agent and nucleating agent in the gas phase of the reactor. In one embodiment, the first polymerization is carried out in or without the chain transfer agent. In this case, the amount of the chain transfer agent may be less than 10.0 mol%, preferably 5.0 mol% or less, more preferably 4.0 mol%, even more preferably 3.0 mol% or less, and still more preferably 1.0 mol% or less, relative to the total amount of monomer and chain transfer agent in the gas phase of the reactor.

[0029] The fluoromonomers used in the first polymerization and the water-soluble fluoropolymers obtained by the first polymerization will be described later.

[0030] In the first manufacturing method of this disclosure, after preparing a water-soluble fluoropolymer, a second polymerization is carried out so that the content of fluororesin in the final aqueous dispersion is 15% by mass or more relative to the mass of the aqueous dispersion. The final aqueous dispersion is an aqueous dispersion containing fluororesin obtained after stopping the polymerization reaction of the second polymerization. The content of fluororesin in the final aqueous dispersion is preferably 18% by mass or more, more preferably 21% by mass or more, and there is no particular upper limit, but it may be 50% by mass or less, 40% by mass or less, or 30% by mass or less.

[0031] In this disclosure, the fluororesin content in the aqueous dispersion is determined by drying 1 g of the aqueous dispersion in a forced-air dryer at 150°C for 60 minutes, measuring the mass of the residue after heating, and expressing the ratio of the mass of the residue to the mass of the aqueous dispersion (1 g) as a percentage.

[0032] Furthermore, in the first manufacturing method of this disclosure, the second polymerization is carried out in substantially the absence of a fluorine-free anionic surfactant from the start of the second polymerization until the content of the fluororesin in the aqueous dispersion reaches 10% by mass relative to the mass of the aqueous dispersion. The fluorine-free anionic surfactant will be described later.

[0033] The polymerization rate of the second polymerization is preferably greater than 3.0 g / (hr·L). Preferably, the polymerization rate of the second polymerization is 10 g / (hr·L) or more, more preferably 20 g / (hr·L) or more, and there is no particular upper limit, but it may be 250 g / (hr·L) or less or 220 g / (hr·L) or less. By adjusting the polymerization rate of the second polymerization within the above range, it is possible to produce an aqueous dispersion containing fluororesin while suppressing the adhesion of the generated polymer to the reactor without using a fluorine-containing surfactant. The polymerization rate of the second polymerization can be adjusted by adjusting the amount of polymerization initiator added, the polymerization temperature, and the number of stirs during polymerization.

[0034] A polymerization initiator may be added during the first polymerization. In one embodiment, during the first polymerization, a polymerization initiator is added in an amount of 0 to 100% by mass of the amount of polymerization initiator initially added to start the first polymerization. In one embodiment, a polymerization initiator can be added during the second polymerization. Polymerization initiators will be described later.

[0035] 1-2. Second manufacturing method In the second manufacturing method of the present disclosure, (1) an aqueous solution containing a water-soluble fluoropolymer is prepared by carrying out a first polymerization of a fluoromonomer in the presence of an aqueous medium and a polymerization initiator, substantially in the absence of a fluorine-containing surfactant, and (2) an aqueous dispersion containing a fluororesin is prepared by carrying out a second polymerization of a fluoromonomer in the presence of the aqueous solution, substantially in the absence of a fluorine-containing surfactant.

[0036] In the second manufacturing method of this disclosure, a water-soluble fluoropolymer is produced in the first polymerization, and a water-insoluble fluororesin is produced in the second polymerization. In one embodiment, in the second polymerization, the water-soluble fluoropolymer and fluoromonomer molecules react, and the polymer chain is extended, thereby producing a water-insoluble fluororesin. Once the fluororesin content in the aqueous dispersion reaches the desired amount, the growth radicals can be deactivated to stop the polymerization reaction.

[0037] In the second manufacturing method of this disclosure, the first polymerization is carried out such that the content of the water-soluble fluoropolymer in the aqueous solution is greater than 0% by mass and less than 1.0% by mass, preferably 0.05 to 0.80% by mass, relative to the mass of the aqueous solution.

[0038] In the second manufacturing method of this disclosure, after preparing a water-soluble fluoropolymer, a second polymerization is carried out such that the content of fluororesin in the final aqueous dispersion is 15% by mass or more relative to the mass of the aqueous dispersion. The final aqueous dispersion is an aqueous dispersion containing fluororesin obtained after stopping the polymerization reaction of the second polymerization. The content of fluororesin in the final aqueous dispersion is preferably 18% by mass or more, more preferably 21% by mass or more, and there is no particular upper limit, but it may be 50% by mass or less, 40% by mass or less, or 35% by mass or less.

[0039] In the second manufacturing method of this disclosure, the amount of radicals generated is adjusted so that the ratio of radical generation amounts (B / A), calculated by the following formula, is 0.70 or less. Ratio of radical generation amounts (B / A) = B / A A: Amount of radicals generated per gram of aqueous medium per minute from the time the polymerization initiator of the first polymerization is first added (A) (mol / (g・min)) B: Amount of radicals generated per gram of aqueous medium per minute from the start of the second polymerization (B) (mol / (g・min))

[0040] "The point in time when the polymerization initiator for the first polymerization is first added" refers to the point in time when the polymerization initiator is added to start the first polymerization, and is different from the point in time when the polymerization initiator is added additionally during the polymerization reaction. Furthermore, if polymerization is carried out in multiple stages, it refers to the point in time when the polymerization initiator is added to start the first polymerization of the multiple stages, and is different from the point in time when the polymerization initiator is added to start the second or subsequent polymerizations.

[0041] The amount of radicals generated (C(t)) can be calculated using the following formula. kd: Decomposition rate constant of polymerization initiator (min) －１F: Frequency factor Ea: Activation energy R: Gas constant T: Polymerization temperature (Kelvin) A: Amount of polymerization initiator added per gram of aqueous medium (g / g) t: Time elapsed since addition of polymerization initiator (minutes) B(t): Amount of polymerization initiator that decomposes per gram of aqueous medium between t (min) and t+1 (min) (g / (g・min)) M: Molecular weight of polymerization initiator C(t): Amount of radicals generated per gram of aqueous medium between t (min) and t+1 (min) (mol / (g・min))

[0042] F (frequency factor) and Ea (activation energy) are values ​​specific to the polymerization initiator. For example, when the polymerization initiator is ammonium persulfate, the following values ​​are obtained: F = 5.62 × 10⁻¹⁰ １８ Ea / R = -17070 For example, if the polymerization initiator is disuccinate peroxide, the following value is obtained: F = 1.30 × 10 １４ Ea / R=-13231

[0043] In the manufacturing method of the present disclosure, the ratio of radical generation (B / A) is 0.70 or less, preferably 0.67 or less, more preferably 0.65 or less, even more preferably 0.64 or less, and still more preferably 0.61 or less. The lower limit is not particularly limited, but may be 0.10 or more, 0.20 or more, or 0.03 or more. Since the second manufacturing method of the present disclosure involves polymerization while appropriately adjusting the amount of radical generation, it is possible to produce an aqueous dispersion containing fluororesin while suppressing the adhesion of the generated polymer to the reactor without using a fluorine-containing surfactant.

[0044] In the manufacturing method of the present disclosure, when PTFE is produced as the fluororesin, the ratio of radical generation (B / A) is 0.70 or less, preferably 0.67 or less, more preferably 0.64 or less, and even more preferably 0.61 or less. The lower limit is not particularly limited, but may be 0.03 or more, 0.05 or more, or 0.10 or more. Since the second manufacturing method of the present disclosure involves polymerization while appropriately adjusting the amount of radical generation, it is possible to produce an aqueous dispersion containing fluororesin while suppressing the adhesion of the produced polymer to the reactor without using a fluorine-containing surfactant.

[0045] In the manufacturing method of the present disclosure, when producing a melt-processable fluororesin as the fluororesin, the ratio of radical generation amount (B / A) is 0.70 or less, preferably 0.65 or less, more preferably 0.60 or less, and the lower limit is not particularly limited but may be 0.10 or more, 0.20 or more, or 0.30 or more. Since the second manufacturing method of the present disclosure performs polymerization while appropriately adjusting the amount of radical generation, it is possible to produce an aqueous dispersion containing a fluororesin while suppressing the adhesion of the generated polymer to the reactor without using a fluorine-containing surfactant.

[0046] The ratio of radical generation (B / A) can be adjusted by controlling the amount of polymerization initiator added, the polymerization temperature, and the number of stirs during polymerization. In particular, by adding a relatively large amount of polymerization initiator initially to start the first polymerization, setting a relatively high polymerization temperature, and slowly stirring the contents of the reactor during the first polymerization, it becomes easier to adjust the ratio of radical generation (B / A) within the above range. That is, a relatively large amount of polymerization initiator and a relatively high polymerization temperature increase the amount of radical generation in the first polymerization. Also, gentle stirring makes the polymerization reaction more difficult to proceed, and the time required for the first polymerization increases. Therefore, since a large amount of polymerization initiator can be decomposed in the first polymerization, the "radical generation amount (A)" can be increased. On the other hand, in the second polymerization, since the amount of polymerization initiator that can be decomposed has decreased, the "radical generation amount (B)" can be decreased.

[0047] If the contents of the reactor are slowly stirred during the first polymerization and thoroughly stirred during the second polymerization, the time when the stirring speed is changed can be considered the start of the second polymerization, and the "amount of radicals generated per gram of aqueous medium per minute from the start of the second polymerization (B)" can be calculated. In one embodiment, if the stirring speed in the first polymerization is set to 100%, the stirring speed in the second polymerization is 150% or more.

[0048] The first polymerization is preferably carried out in the presence of either or both of the chain transfer agent and the nucleating agent, or in the absence of both the chain transfer agent and the nucleating agent. In this case, the total amount of the chain transfer agent and the nucleating agent is preferably 5.0 mol% or less, more preferably 4.0 mol%, even more preferably 3.0 mol% or less, and still more preferably 1.0 mol% or less, relative to the total amount of monomer, chain transfer agent and nucleating agent in the gas phase of the reactor. In one embodiment, the first polymerization is carried out in or without the chain transfer agent. In this case, the amount of the chain transfer agent may be less than 10.0 mol%, preferably 5.0 mol% or less, more preferably 4.0 mol%, even more preferably 3.0 mol% or less, and still more preferably 1.0 mol% or less, relative to the total amount of monomer and chain transfer agent in the gas phase of the reactor.

[0049] In the second polymerization, it is preferable to thoroughly stir the contents of the reactor. By thoroughly stirring the contents of the reactor, the polymerization reaction can proceed smoothly with a small amount of radicals, and the fluororesin content in the aqueous dispersion can be rapidly increased.

[0050] In the second manufacturing method of this disclosure, the polymerization rate of the first polymerization is preferably 3.0 g / (hr·L) or less. The polymerization rate of the first polymerization is preferably 2.0 g / (hr·L) or less, more preferably 1.5 g / (hr·L) or less, and the lower limit is not particularly limited, but may be 0.03 g / (hr·L) or more or 0.05 g / (hr·L) or more. By adjusting the polymerization rate of the first polymerization to within the above range, the adhesion of the produced polymer to the reactor can be further suppressed without using a fluorine-containing surfactant. The polymerization rate of the first polymerization can be adjusted by adjusting the amount of polymerization initiator added, the polymerization temperature, and the number of stirs during polymerization.

[0051] Secondly, the polymerization rate is preferably greater than 3.0 g / (hr·L). Secondly, the polymerization rate is preferably 10 g / (hr·L) or more, more preferably 20 g / (hr·L) or more, and there is no particular upper limit, but it may be 250 g / (hr·L) or less or 220 g / (hr·L) or less. Secondly, by adjusting the polymerization rate within the above range, the fluororesin content in the aqueous dispersion can be rapidly increased while suppressing the adhesion of the generated polymer to the reactor without using a fluorine-containing surfactant. Secondly, the polymerization rate can be adjusted by adjusting the amount of polymerization initiator added, the polymerization temperature, and the number of stirs during polymerization.

[0052] A polymerization initiator may be added during the first polymerization. In one embodiment, during the first polymerization, a polymerization initiator is added in an amount of 0 to 100% by mass of the amount of polymerization initiator initially added to start the first polymerization. By not adding a polymerization initiator during the first polymerization, or by adding a limited amount of polymerization initiator, it becomes easy to adjust the ratio of radical generation (B / A) to the above range.

[0053] In one embodiment, a polymerization initiator can be added during the second polymerization. The polymerization initiator will be described later.

[0054] 1-3. Third manufacturing method In the third manufacturing method of the present disclosure, (1) an aqueous solution containing a water-soluble fluoropolymer is prepared by carrying out a first polymerization of a fluoromonomer in the presence of an aqueous medium and a polymerization initiator, substantially in the absence of a fluorine-containing surfactant, and (2) an aqueous dispersion containing a fluororesin is prepared by carrying out a second polymerization of a fluoromonomer in the presence of the aqueous solution, substantially in the absence of a fluorine-containing surfactant.

[0055] In the third manufacturing method of this disclosure, a water-soluble fluoropolymer is produced in the first polymerization, and a water-insoluble fluororesin is produced in the second polymerization. In one embodiment, in the second polymerization, the water-soluble fluoropolymer and fluoromonomer molecules react, and the polymer chain is extended, thereby producing a water-insoluble fluororesin. Once the fluororesin content in the aqueous dispersion reaches the desired amount, the growth radicals can be deactivated to stop the polymerization reaction.

[0056] In the third manufacturing method of this disclosure, the first polymerization is carried out such that the content of the water-soluble fluoropolymer in the aqueous solution is greater than 0% by mass and less than 1.0% by mass relative to the mass of the aqueous solution.

[0057] In the third manufacturing method of this disclosure, the polymerization rate of the first polymerization is preferably 3.0 g / (hr·L) or less. Preferably, the polymerization rate of the first polymerization is 2.0 g / (hr·L) or less, more preferably 1.5 g / (hr·L) or less, and the lower limit is not particularly limited, but may be 0.03 g / (hr·L) or more or 0.05 g / (hr·L) or more. By adjusting the polymerization rate of the first polymerization to within the above range, an aqueous dispersion containing fluororesin can be produced without using a fluorine-containing surfactant, while suppressing the adhesion of the generated polymer to the reactor. The polymerization rate of the first polymerization can be adjusted by adjusting the amount of polymerization initiator added, the polymerization temperature, and the number of stirs during polymerization.

[0058] In one embodiment, a water-soluble fluoropolymer having a melting point of 250 to 330°C is prepared by a first polymerization. In another embodiment, a water-soluble fluoropolymer having a glass transition temperature of 10°C or less is prepared by a first polymerization. The fluoromonomer used in the first polymerization and the water-soluble fluoropolymer obtained by the first polymerization will be described later.

[0059] The first polymerization is preferably carried out in the presence of either or both of the chain transfer agent and the nucleating agent, or in the absence of both the chain transfer agent and the nucleating agent. In this case, the total amount of the chain transfer agent and the nucleating agent is preferably 5.0 mol% or less, more preferably 4.0 mol%, even more preferably 3.0 mol% or less, and still more preferably 1.0 mol% or less, relative to the total amount of monomer, chain transfer agent and nucleating agent in the gas phase of the reactor. In one embodiment, the first polymerization is carried out in or without the chain transfer agent. In this case, the amount of the chain transfer agent may be less than 10.0 mol%, preferably 5.0 mol% or less, more preferably 4.0 mol%, even more preferably 3.0 mol% or less, and still more preferably 1.0 mol% or less, relative to the total amount of monomer and chain transfer agent in the gas phase of the reactor.

[0060] In the first polymerization in the third manufacturing method of this disclosure, a pyrolysis-type radical polymerization initiator is used as the polymerization initiator. The pyrolysis-type radical polymerization initiator will be described later.

[0061] In the third manufacturing method of this disclosure, the first polymerization is initiated by adding a pyrolysis-type radical polymerization initiator. The first polymerization is continued for a time sufficient to decompose 90% or more by mass of the pyrolysis-type radical polymerization initiator, assuming that the amount of pyrolysis-type radical polymerization initiator initially added is 100% by mass. A polymerization initiator may be added during the first polymerization, but it is preferable that the amount of polymerization initiator added during the first polymerization be within the range of 0 to 100% by mass of the amount of polymerization initiator initially added to initiate the first polymerization, as this makes it easier to adjust the amount of decomposition of the pyrolysis-type radical polymerization initiator.

[0062] In the third manufacturing method of this disclosure, after preparing a water-soluble fluoropolymer, a second polymerization is carried out such that the content of fluororesin in the final aqueous dispersion is 15% by mass or more relative to the mass of the aqueous dispersion. The final aqueous dispersion is an aqueous dispersion containing fluororesin obtained after stopping the polymerization reaction of the second polymerization. The content of fluororesin in the final aqueous dispersion is preferably 18% by mass or more, more preferably 21% by mass or more, and there is no particular upper limit, but it may be 50% by mass or less, 40% by mass or less, or 30% by mass or less.

[0063] Furthermore, in the third manufacturing method of this disclosure, the second polymerization is carried out in substantially the absence of a fluorine-free anionic surfactant from the start of the second polymerization until the content of the fluororesin in the aqueous dispersion reaches 10% by mass relative to the mass of the aqueous dispersion. The fluorine-free anionic surfactant will be described later.

[0064] The polymerization rate of the second polymerization is preferably greater than 3.0 g / (hr·L). Preferably, the polymerization rate of the second polymerization is 10 g / (hr·L) or more, more preferably 20 g / (hr·L) or more, and there is no particular upper limit, but it may be 250 g / (hr·L) or less or 220 g / (hr·L) or less. By adjusting the polymerization rate of the second polymerization within the above range, it is possible to produce an aqueous dispersion containing fluororesin while suppressing the adhesion of the generated polymer to the reactor without using a fluorine-containing surfactant. The polymerization rate of the second polymerization can be adjusted by adjusting the amount of polymerization initiator added, the polymerization temperature, and the number of stirs during polymerization.

[0065] In one embodiment, a polymerization initiator can be added during the second polymerization. The polymerization initiator will be described later.

[0066] Next, the common components of the first manufacturing method, the second manufacturing method, and the third manufacturing method (in this disclosure, the first to third manufacturing methods may be collectively referred to as the "manufacturing method of this disclosure" or "manufacturing method") will be described in detail.

[0067] (Fluorine-containing surfactant) In the manufacturing method of the present disclosure, polymerization is carried out in substantially the absence of a fluorine-containing surfactant throughout the entire polymerization period.

[0068] In this disclosure, "substantially absent from fluorine-containing surfactants" means that the amount of fluorine-containing surfactant in the aqueous medium is 10 ppm by mass or less. Preferably, the amount of fluorine-containing surfactant in the aqueous medium is 1 ppm by mass or less, more preferably 100 ppb by mass or less, even more preferably 10 ppb by mass or less, and even more preferably 1 ppb by mass or less. "Polymerization carried out in the absence of fluorine-containing surfactants" includes polymerization carried out without intentionally adding fluorine-containing surfactants.

[0069] Examples of fluorinated surfactants include anionic fluorinated surfactants, nonionic fluorinated surfactants, and cationic fluorinated surfactants. Fluorinated surfactants include both non-reactive and reactive fluorinated surfactants.

[0070] (Aqueous medium) The aqueous medium is a reaction medium for polymerization and means a liquid containing water. The above aqueous medium is not particularly limited as long as it contains water, and may contain water and, for example, a fluorine-free organic solvent such as ether or ketone, and / or a fluorine-containing organic solvent with a boiling point of 40°C or less.

[0071] As an aqueous medium, an aqueous medium containing only water, or an aqueous medium containing only water and a fluorine-free organic solvent, is preferred because it allows polymerization to proceed smoothly, and an aqueous medium containing only water is more preferred.

[0072] The water content in the aqueous medium is preferably 90% by mass or more, more preferably 95% by mass or more, even more preferably 99.0% by mass or more, even more preferably 99.5% by mass or more, particularly preferably 99.9% by mass or more, and may be 100% by mass, in order to facilitate polymerization.

[0073] (Coinitiator) In one embodiment of the production method of the present disclosure, a thermal decomposition type radical polymerization initiator is used as the polymerization initiator. In particular, in the first polymerization in the first to third production methods, when a thermal decomposition type radical polymerization initiator is used, it becomes easier to adjust the polymerization rate and the decomposition amount of the polymerization initiator.

[0074] A thermal decomposition type radical polymerization initiator is a compound that decomposes by heat to generate radicals. In one embodiment, the thermal decomposition type radical polymerization initiator decomposes at the polymerization temperature (for example, 85 °C or higher) to generate radicals.

[0075] Examples of the polymerization initiator and the thermal decomposition type radical polymerization initiator include water-soluble radical polymerization initiators. The water-soluble radical polymerization initiator may be a known water-soluble peroxide, for example, ammonium salts, potassium salts, sodium salts of persulfuric acid, perboric acid, perchloric acid, perphosphoric acid, percarbonic acid, etc., organic peroxides such as disuccinic acid peroxide, diglutaric acid peroxide, t-butyl permaleate, t-butyl hydroperoxide, etc. Among them, persulfates are preferred, and potassium persulfate (K ２ S ２ O ８ ), ammonium persulfate ((NH ４ )) ２ S ２ O ８ ), sodium persulfate (Na ２ S ２ O ８ ) are more preferred, and ammonium persulfate is even more preferred.

[0076] In the second polymerization in the first to third production methods, a thermal decomposition type radical polymerization initiator or a redox initiator combining an oxidizing agent and a reducing agent can be used.

[0077] Examples of oxidizing agents include persulfates, organic peroxides, potassium permanganate, manganese triacetate, and ammonium cerium nitrate. Examples of reducing agents include sulfites, bisulfites, bromates, diimines, and oxalic acid. Examples of persulfates include ammonium persulfate and potassium persulfate. Examples of sulfites include sodium sulfite and ammonium sulfite. To increase the decomposition rate of the initiator, it is also preferable to add copper salts and iron salts to the redox initiator combination. Examples of copper salts include copper(II) sulfate, and examples of iron salts include iron(II) sulfate.

[0078] Examples of the redox initiators mentioned above include potassium permanganate / oxalic acid, potassium permanganate / ammonium oxalate, ammonium persulfate / bisulfite / ferrous sulfate, ammonium persulfate / ammonium sulfite, manganese triacetate / oxalic acid, cerium ammonium nitrate / oxalic acid, bromate / bisulfite, etc., with potassium permanganate / oxalic acid and ammonium persulfate / bisulfite / ferrous sulfate being preferred. When using a redox initiator, either an oxidizing agent or a reducing agent may be charged into the polymerization tank beforehand, and then the other may be added continuously or intermittently to initiate polymerization. For example, when using potassium permanganate / oxalic acid, it is preferable to charge oxalic acid into the polymerization tank and then continuously add potassium permanganate thereto.

[0079] There are no particular limitations on the amount of polymerization initiator added, but it is sufficient to add at least an amount that does not significantly reduce the polymerization rate (for example, a few ppm relative to water concentration) in one lump sum at the beginning of polymerization, or sequentially or continuously. The upper limit is a range in which the reaction temperature can be increased while removing heat from the apparatus surface using the heat of the polymerization reaction, and a more preferable upper limit is a range in which the heat of the polymerization reaction can be removed from the apparatus surface.

[0080] In the manufacturing method of this disclosure, the amount of polymerization initiator initially added is preferably 30 to 5000 ppm by mass, more preferably 40 ppm by mass or more, even more preferably 50 ppm by mass or more, even more preferably 3000 ppm by mass or less, and even more preferably 2000 ppm by mass or less, relative to the aqueous medium. By adjusting the amount of polymerization initiator initially added within the above range, it becomes easier to adjust the polymerization rate, the amount of radicals generated, and the amount of polymerization initiator decomposition.

[0081] In the manufacturing method of this disclosure, when producing PTFE as a fluororesin, the amount of polymerization initiator added initially is preferably 30 to 500 ppm by mass, more preferably 40 ppm by mass or more, even more preferably 50 ppm by mass or more, even more preferably 400 ppm by mass or less, and even more preferably 300 ppm by mass or less, relative to the aqueous medium. By adjusting the amount of polymerization initiator added initially within the above range, it becomes easier to adjust the polymerization rate, the amount of radicals generated, and the amount of polymerization initiator decomposition.

[0082] In the manufacturing method of the present disclosure, when producing a melt-processable fluororesin as the fluororesin, the amount of polymerization initiator initially added is preferably 30 to 5000 ppm by mass, more preferably 50 ppm by mass or more, even more preferably 80 ppm by mass or more, even more preferably 3000 ppm by mass or less, and even more preferably 2000 ppm by mass or less, relative to the aqueous medium. By adjusting the amount of polymerization initiator initially added within the above range, it becomes easier to adjust the polymerization rate, the amount of radicals generated, and the amount of polymerization initiator decomposition.

[0083] A polymerization initiator may be added during the first polymerization in the first to third manufacturing methods. In one embodiment, during the first polymerization, a polymerization initiator is added in an amount of 0 to 100% by mass of the amount of polymerization initiator initially added to start the first polymerization.

[0084] A polymerization initiator may be added in the second polymerization step in the first and third manufacturing methods.

[0085] In the manufacturing method of the present disclosure, the total amount of polymerization initiator added for polymerization is preferably 0.00001 to 10% by mass, more preferably 0.0001% by mass or more, even more preferably 0.001% by mass or more, even more preferably 0.01% by mass or more, preferably 5% by mass or less, and more preferably 2% by mass or less, relative to the aqueous medium.

[0086] (Chain transfer agent) In the manufacturing method of the present disclosure, polymerization of fluoromonomers can be carried out in the presence of a chain transfer agent. In particular, in the first polymerization in the first to third manufacturing methods, using a chain transfer agent makes it even easier to adjust the polymerization rate and the amount of decomposition of the polymerization initiator.

[0087] Examples of chain transfer agents include esters such as dimethyl malonate, diethyl malonate, methyl acetate, ethyl acetate, butyl acetate, and dimethyl succinate, as well as various halogenated hydrocarbons such as isopentane, methane, ethane, propane, butane, pentane, hexane, heptane, methanol, isopropanol, acetone, various mercaptans, and carbon tetrachloride, and cyclohexane. Among these, at least one selected from the group consisting of hydrocarbon compounds and alcohols is preferred as a chain transfer agent, with isopentane, methane, ethane, propane, butane, pentane, hexane, heptane, methanol, and isopropanol being more preferred.

[0088] The amount of the above-mentioned chain transfer agent used is usually 1 to 50,000 ppm by mass, preferably 1 to 20,000 ppm by mass, relative to the total amount of fluoromonomer supplied.

[0089] The amount of chain transfer agent used in the first polymerization is preferably 1 to 10,000 ppm by mass, and more preferably 1 to 5,000 ppm by mass, relative to the total amount of fluoromonomer supplied in the first polymerization.

[0090] When the chain transfer agent is a liquid at room temperature and atmospheric pressure, the amount of chain transfer agent used is preferably 1 to 1000 ppm by mass, and more preferably 1 to 500 ppm by mass, relative to the total amount of fluoromonomer supplied.

[0091] The above-mentioned chain transfer agent may be added to the reactor all at once before polymerization begins, all at once after polymerization begins, added in multiple portions during polymerization, or added continuously during polymerization.

[0092] (Nucleating agent) In the manufacturing method of this disclosure, polymerization may be carried out in the presence of a nucleating agent. By adding a nucleating agent in the early stages of polymerization, the average primary particle size of the particles contained in the aqueous dispersion is reduced, and an aqueous dispersion with excellent stability can be obtained.

[0093] Examples of nucleating agents include monocarboxylic acids, dicarboxylic acids, perfluoropolyether (PFPE) acids or salts thereof, hydrocarbon-containing surfactants, etc. Preferably, at least one selected from the group consisting of monocarboxylic acids, dicarboxylic acids, perfluoropolyether (PFPE) acids or salts thereof, and fluorine-free nonionic surfactants is preferred, with monocarboxylic acids or monocarboxylic acid salts being more preferred. Examples of monocarboxylic acids or monocarboxylic acid salts include formic acid or formate salts.

[0094] Among the nucleating agents, fluorine-free nonionic surfactants are preferred. Fluorine-free nonionic surfactants preferably do not contain aromatic moieties.

[0095] Examples of fluorine-free nonionic surfactants include nonionic surfactants represented by general formula (i) and nonionic surfactants represented by general formula (ii). ６ -O-A １ -H (i) (wherein, R ６ A is a linear or branched primary or secondary alkyl group having 8 to 18 carbon atoms. １ (This is a polyoxyalkylene chain.) ７ -C ６ H ４ -O-A ２ -H (ii) (wherein, R ７ A is a linear or branched alkyl group having 4 to 12 carbon atoms. ２ (This is a polyoxyalkylene chain.)

[0096] As the fluorine-free nonionic surfactant, at least one selected from the group consisting of nonionic surfactants represented by general formula (i) and nonionic surfactants represented by general formula (ii) is preferred, and the nonionic surfactant represented by general formula (i) is more preferred.

[0097] Examples of fluorine-free nonionic surfactants include Dow Chemical Company's Triton® X series (X15, X45, X100, etc.), Tergitol® 15-S series, Tergitol® TMN series (TMN-6, TMN-10, TMN-100, etc.), Tergitol® L series, and BASF's Pluronic® R series (31R1, 17R2, 10R5, 25R4, Examples include m-22, n-23), Iconol® TDA series (TDA-6, TDA-9, TDA-10), Clariant's Genapol series (X080, etc.), Daiichi Kogyo Seiyaku's Neugen TDS series (TDS-80, TDS-100, etc.), Lion Corporation's Leocol TD series (TD-90, etc.), Lion Corporation's Lionol® TD series, Harcross Chemicals' T-Det A series (A-138, A-139, A-1315, etc.), and Nippon Oil & Fats Co., Ltd.'s Dispanol TOC.

[0098] The amount of nucleating agent added can be appropriately selected depending on the type of nucleating agent. The amount of nucleating agent added may be 5000 ppm by mass or less relative to the aqueous medium, preferably 1000 ppm by mass or less, more preferably 500 ppm by mass or less, even more preferably 100 ppm by mass or less, particularly preferably 50 ppm by mass or less, most preferably 10 ppm by mass or less, preferably 0.01 ppm by mass or more, and more preferably 0.1 ppm by mass or more.

[0099] (Fluorine-free anionic surfactant) In the first to third manufacturing methods, it is preferable to carry out the first polymerization in the substantially absence of a fluorine-free anionic surfactant.

[0100] In the first to third manufacturing methods, it is preferable to carry out the polymerization in substantially the absence of a fluorine-free anionic surfactant for a period from the start of the second polymerization until the content of the fluororesin in the aqueous dispersion reaches 10% by mass relative to the mass of the aqueous dispersion.

[0101] In this disclosure, "substantially in the absence of fluorine-free anionic surfactants" means that the amount of fluorine-free anionic surfactant in the aqueous medium is 10 ppm by mass or less. The amount of fluorine-free anionic surfactant in the aqueous medium is preferably 1 ppm by mass or less, more preferably 100 ppb by mass or less, even more preferably 10 ppb by mass or less, and even more preferably 1 ppb by mass or less. "Polymerization carried out in the absence of fluorine-free anionic surfactants" includes polymerization carried out without intentionally adding fluorine-free anionic surfactants.

[0102] In the first to third manufacturing methods, polymerization can be carried out in the presence of a fluorine-free anionic surfactant after the content of fluororesin in the aqueous dispersion reaches 10% by mass relative to the mass of the aqueous dispersion.

[0103] The amount of fluorine-free anionic surfactant during the above period is preferably 0.0001 to 10% by mass, more preferably 0.001% by mass or more, even more preferably 0.01% by mass or more, even more preferably 0.1% by mass or more, and more preferably 1% by mass or less, based on 100% by mass of the aqueous medium. The amount of fluorine-free anionic surfactant used is appropriately determined depending on the type of monomer used, the molecular weight of the target fluororesin, etc.

[0104] Fluorine-free anionic surfactants are non-fluorine hydrocarbon emulsifiers that do not contain fluorine atoms. Examples of fluorine-free anionic surfactants that can be used include those described in Japanese Patent Publication No. 2013-542308, Japanese Patent Publication No. 2013-542309, and Japanese Patent Publication No. 2013-542310.

[0105] Examples of fluorine-free anionic surfactants include carboxylic acids or their salts, sulfonic acids or their salts, and sulfuric acids or their salts. Fluorine-free anionic surfactants typically have a hydrophilic portion, such as a carboxylic acid, carboxylate salt, sulfonic acid, sulfonate, sulfuric acid, or sulfate salt, and a hydrophobic portion, such as a long-chain hydrocarbon portion, such as an alkyl group.

[0106] Examples of fluorine-free anionic surfactants include Resolution Performance Products' Versatic® 10 and BASF's Avanel S series (S-70, S-74, etc.).

[0107] As for fluorine-free anionic surfactants, R Ｚ - (L-M) ｘ (In the formula, R Ｚ However, it is a hydrophobic hydrocarbon moiety containing one or more carbon atoms. L may be the same or different in each occurrence and represents an ionic hydrophilic moiety, and M may be the same or different in each occurrence and represents one or more counterions of the ionic hydrophilic moiety. x represents the number of groups represented by -L-M bonded to Rz, and is an integer from 1 to 3. An anionic surfactant represented by ) is an example. Ｚ As for L, a hydrocarbon group having 1 to 100 carbon atoms, which may contain heteroatoms, is preferred. The heteroatoms may be inserted between carbon atoms or may be included in substituents bonded to carbon atoms. As for L, -ArSO ３ － , -SO ３ － , -SO ４ -, -PO ３ － or -COO － This is preferable. -ArSO ３ － It is an aryl sulfonate. M is H, a metal atom, NR ５Ｚ ４ Preferably, imidazolium which may have substituents, pyridinium which may have substituents, or phosphonium which may have substituents. ５ＺThe element is preferably H or an organic group (preferably an alkyl group having 1 to 3 carbon atoms). More specifically, the anionic surfactants described below are examples.

[0108] As for fluorine-free anionic surfactants, R Ｚ -LM (wherein, R Ｚ However, it is a monovalent organic group containing one or more carbon atoms. L is -ArSO ３ － , -SO ３ － , -SO ４ -, -PO ３ － or -COO － And M is H, a metal atom, NR ５Ｚ ４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium, R ５Ｚ is H or an organic group, -ArSO ３ － Anionic surfactants, represented by aryl sulfonates, are also mentioned. Specifically, these include CH4 compounds such as lauric acid and lauryl sulfate (dodecyl sulfate). ３ - (CH ２ ) ｎ Examples include those expressed by -L-M (wherein n is an integer between 6 and 17, and L and M are the same as above). Ｚ However, it may be a linear or branched alkyl group having 1 or more carbon atoms, which may have substituents, or a cyclic alkyl group having 3 or more carbon atoms, which may have substituents. Ｚ If the alkyl group has three or more carbon atoms, it may contain a monovalent or divalent heterocycle, or it may form a ring. Ｚ However, it is preferable that it be an alkyl group having 3 to 18 carbon atoms. Ｚ However, a mixture of alkyl groups having 12 to 16 carbon atoms, where L-M is a sulfate, can also be used.

[0109] Other compounds with surfactant properties include R ６Ｚ (-L-M) ２ (In the formula, R ６Ｚis a monovalent organic group containing one or more carbon atoms. L is -ArSO ３ － , -SO ３ － , -SO ４ -, -PO ３ － or -COO － where M is H, a metal atom, NR ５Ｚ ４ , optionally substituted imidazolium, optionally substituted pyridinium or optionally substituted phosphonium, R ５Ｚ is H or an organic group, -ArSO ３ － is an arylsulfonate. ) Also included are anionic surfactants represented by. R ６Ｚ may be a linear or branched alkylene group having 1 or more carbon atoms which may have a substituent, or a cyclic alkylene group having 3 or more carbon atoms which may have a substituent. When the alkylene group of R ６Ｚ has 3 or more carbon atoms, it may contain a monovalent or divalent heterocyclic ring or may form a ring.

[0110] Examples of the fluorine-free anionic surfactant include R ７Ｚ (-L-M) ３ (wherein R ７Ｚ is a monovalent organic group containing one or more carbon atoms. L is -ArSO ３ － , -SO ３ － , -SO ４ -, -PO ３ － or -COO － where M is H, a metal atom, NR ５Ｚ ４ , optionally substituted imidazolium, optionally substituted pyridinium or optionally substituted phosphonium, R ５Ｚ is H or an organic group. -ArSO ３ － is an arylsulfonate. ) Also included are anionic surfactants represented by. R ７ＺHowever, it may be a linear or branched alkylidine group having 1 or more carbon atoms, which may have substituents, or a cyclic alkylidine group having 3 or more carbon atoms, which may have substituents. ７Ｚ If the alkylidine group has three or more carbon atoms, it may contain a monovalent or divalent heterocycle, or it may form a ring. ５ｚ H or an alkyl group is preferred, H or an alkyl group having 1 to 10 carbon atoms is more preferred, and H or an alkyl group having 1 to 4 carbon atoms is even more preferred.

[0111] In this disclosure, unless otherwise specified, “substituent” means a substituteable group. Examples of such “substituent” are aliphatic groups, aromatic groups, heterocyclic groups, acyl groups, acyloxy groups, acylamino groups, aliphatic oxy groups, aromatic oxy groups, heterocyclic oxy groups, aliphatic oxycarbonyl groups, aromatic oxycarbonyl groups, heterocyclic oxycarbonyl groups, carbamoyl groups, aliphatic sulfonyl groups, aromatic sulfonyl groups, heterocyclic sulfonyl groups, aliphatic sulfonyloxy groups, aromatic sulfonyloxy groups, heterocyclic sulfonyloxy groups, sulfamoyl groups, aliphatic sulfonamide groups, aromatic sulfonamide groups, heterocyclic sulfonamide groups, amino groups, aliphatic amino This includes a no group, an aromatic amino group, a heterocyclic amino group, an aliphatic oxycarbonylamino group, an aromatic oxycarbonylamino group, a heterocyclic oxycarbonylamino group, an aliphatic sulfinyl group, an aromatic sulfinyl group, an aliphatic thio group, an aromatic thio group, a hydroxy group, a cyano group, a sulfo group, a carboxyl group, an aliphatic oxyamino group, an aromatic oxyamino group, a carbamoylamino group, a sulfamoylamino group, a halogen atom, a sulfamoylcarbamoyl group, a carbamoylsulfamoyl group, a dialiphatic oxyphosphinyl group, or a diaromatic oxyphosphinyl group.

[0112] Siloxane hydrocarbon surfactants are another example of fluorine-free anionic surfactants. Siloxane hydrocarbon surfactants are also disclosed in U.S. Patent No. 6,841,616.

[0113] Examples of fluorine-free anionic surfactants include the sulfosuccinate surfactant Lankropol® K8300 from Akzo Nobel Surface Chemistry LLC. Examples of sulfosuccinate surfactants include sodium diisodecyl sulfosuccinate (Emulsogen® SB10 from Clariant) and sodium diisotridecyl sulfosuccinate (Policol® TR / LNA from Cesapinia Chemicals).

[0114] As a fluorine-free anionic surfactant, there is PolyFox® surfactant from Omnova Solutions, Inc. ＴＭ PF-156A, PolyFox ＴＭ Other examples include the PF-136A, etc.

[0115] Examples of fluorine-free anionic surfactants include those with the general formula (1): (In the formula, R １ ~R ５ represents H or a monovalent substituent, however, R １ and R ３ Of these, at least one is a general formula: -Y-R ６ The group indicated by, R ２ and R ５ Of these, at least one is a group represented by the general formula: -X-A, or the general formula: -Y-R ６ The group shown is represented by . Also, X is a divalent linking group or bond, which is the same or different in each occurrence; A is -COOM, -SO, which is the same or different in each occurrence. ３ M or -OSO ３ M (where M is H, metal atom, NR) ７ ４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium, R ７ ( is H or an organic group); Y is the same or different in each occurrence, -S (=O) ２ -, -O-, -COO-, -OCO-, -CONR ８ - and -NR ８A divalent linking group selected from the group consisting of CO-, or a bond, R ８ is H or an organic group; R ６ R represents an alkyl group having one or more carbon atoms, which may contain at least one group selected from the group consisting of a carbonyl group, an ester group, an amide group, and a sulfonyl group between the carbon atoms, either identically or differently in each occurrence. １ ~R ５ Any two of these may bond with each other to form a ring. A surfactant represented by (hereinafter also referred to as surfactant (1)) is preferably exemplified.

[0116] Surfactants (1) will be explained.

[0117] In the formula, R １ ~R ５ represents H or a monovalent substituent, however, R １ and R ３ Of these, at least one is a general formula: -Y-R ６ The group indicated by, R ２ and R ５ Of these, at least one is a group represented by the general formula: -X-A, or the general formula: -Y-R ６ This represents the group indicated by R. １ ~R ５ Any two of these may combine with each other to form a ring.

[0118] R １ The substituents that the alkyl group may have are preferably halogen atoms, linear or branched alkyl groups having 1 to 10 carbon atoms, or cyclic alkyl groups having 3 to 10 carbon atoms, and hydroxyl groups, with methyl groups and ethyl groups being particularly preferred.

[0119] R １The alkyl group described above preferably does not contain a carbonyl group. The alkyl group may have 75% or less of the hydrogen atoms bonded to the carbon atom substituted with halogen atoms, 50% or less substituted with halogen atoms, or 25% or less substituted with halogen atoms, but it is preferable that it is a non-halogenated alkyl group that does not contain halogen atoms such as fluorine atoms or chlorine atoms. The alkyl group may preferably have no substituents whatsoever.

[0120] R １ Preferably, the alkyl group is a linear or branched alkyl group having 1 to 10 carbon atoms, which may have substituents, or a cyclic alkyl group having 3 to 10 carbon atoms, which may have substituents; more preferably, a linear or branched alkyl group having 1 to 10 carbon atoms that does not contain a carbonyl group, or a cyclic alkyl group having 3 to 10 carbon atoms that does not contain a carbonyl group; even more preferably, a linear or branched alkyl group having 1 to 10 carbon atoms without substituents; and even more preferably, a linear or branched alkyl group having 1 to 3 carbon atoms without substituents, and a methyl group (-CH ３ ) or ethyl group (-C ２ H ５ ) is particularly preferred, and a methyl group (-CH ３ ) is the most preferable.

[0121] As a monovalent substituent, the general formula is: -Y-R ６ A group represented by the formula: -X-A, -H, and C which may have a substituent. １－２０ alkyl group, -NH ２ , - NHR ９ (R ９ (Organic group), -OH, -COOR ９ (R ９ (is an organic group) or -OR ９ (R ９ (An organic group is preferred.) The number of carbon atoms in the alkyl group is preferably 1 to 10.

[0122] R ９ C １－１０ alkyl group or C １－１０ The alkylcarbonyl group is preferred, C １－４ alkyl group or C １－４The alkylcarbonyl group is more preferable.

[0123] In the formula, X represents a divalent linking group or bond, which may be the same or different in each occurrence. ６ If X does not contain any carbonyl group, ester group, amide group, or sulfonyl group, it is preferable that X is a divalent linking group containing at least one selected from the group consisting of carbonyl group, ester group, amide group, and sulfonyl group.

[0124] X is -CO-, -S (=O) ２ -, -O-, -COO-, -OCO-, -S (=O) ２ -O-, -O-S (=O) ２ -, -CONR ８ - and -NR ８ A divalent linking group containing at least one bond selected from the group consisting of CO-, C １－１０ An alkylene group or bond is preferred. ８ represents H or an organic group.

[0125] R ８ Alkyl groups are preferred as the organic groups in R. ８ For example, H or C １－１０ The organic group is preferably H or C １－４ The organic group is more preferably H or C １－４ Alkyl alkyl groups are more preferred, and H is even more preferred.

[0126] In the formula, A is the same or different in each occurrence, -COOM, -SO ３ M or -OSO ３ M (where M is H, metal atom, NR) ７ ４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium, R ７ is H or an organic group. There are four R ７ (These may be the same or different.) In general formula (1), one preferred embodiment is that A is -COOM.

[0127] R ７ Alkyl alkyl groups are preferred as the organic groups in R.７ For example, H or C １－１０ The organic group is preferably H or C １－４ The organic group is more preferably H or C １－４ Alkyl alkyl groups are even more preferred. Examples of the metal atoms include alkali metals (Group 1), alkaline earth metals (Group 2), etc., with Na, K, or Li being preferred.

[0128] M can be H, a metal atom, or NR ７ ４ Preferably, H, alkali metals (Group 1), alkaline earth metals (Group 2), or NR ７ ４ More preferably, H, Na, K, Li or NH ４ More preferably, Na, K or NH ４ More preferably, Na or NH ４ NH is particularly preferred. ４ Most preferable.

[0129] In the formula, Y is the same or different in each occurrence, and -S (=O) ２ -, -O-, -COO-, -OCO-, -CONR ８ - and -NR ８ A divalent linking group selected from the group consisting of CO-, or a bond, R ８ represents H or an organic group.

[0130] Y is a combination of -O-, -COO-, -OCO-, and -CONR. ８ - and -NR ８ A divalent linking group selected from the group consisting of CO- is preferred, and a divalent linking group selected from the group consisting of -COO- and -OCO- is more preferred.

[0131] R ８ Alkyl alkyl groups are preferred as the organic groups in R. ８ For example, H or C １－１０ The organic group is preferably H or C １－４ The organic group is more preferably H or C １－４ Alkyl alkyl groups are more preferred, and H is even more preferred.

[0132] In the formula, R ６R represents an alkyl group having one or more carbon atoms, which may contain at least one selected from the group consisting of a carbonyl group, an ester group, an amide group, and a sulfonyl group between the carbon atoms, either identically or differently in each appearance. ６ The number of carbon atoms in the organic group is preferably 2 or more, preferably 20 or less, more preferably 2 to 20, and even more preferably 2 to 10.

[0133] R ６ The alkyl group, when it has two or more carbon atoms, may contain at least one or more groups selected from the group consisting of a carbonyl group, an ester group, an amide group, and a sulfonyl group between the carbon atoms, but the alkyl group does not contain any of these groups at either end. ６ The alkyl group may have 75% or less of the hydrogen atoms bonded to the carbon atom substituted with halogen atoms, 50% or less substituted with halogen atoms, or 25% or less substituted with halogen atoms, but it is preferable that it is a non-halogenated alkyl group that does not contain halogen atoms such as fluorine atoms or chlorine atoms.

[0134] R ６ For example, the general formula is: -R １０ -CO-R １１ The base shown by, general formula: -R １０ -COO-R １１ The base shown by, general formula: -R １１ The base shown by, general formula: -R １０ -NR ８ CO-R １１ The base shown by, or the general formula: -R １０ -CONR ８ -R １１ The base shown by (wherein R ８ R represents H or an organic group. １０ is an alkylene group, R １１ R is preferable (an alkyl group which may have substituents). ６ For example, the general formula is: -R １０ -CO-R １１ The group indicated by is more preferable.

[0135] R ８ Alkyl alkyl groups are preferred as the organic groups in R.８ For example, H or C １－１０ The organic group is preferably H or C １－４ The organic group is more preferably H or C １－４ Alkyl alkyl groups are more preferred, and H is even more preferred.

[0136] R １０ The number of carbon atoms in the alkylene group is preferably 1 or more, more preferably 3 or more, preferably 20 or less, more preferably 12 or less, even more preferably 10 or less, and particularly preferably 8 or less. Also, R １０ The number of carbon atoms in the alkylene group is preferably 1 to 20, more preferably 1 to 10, and even more preferably 3 to 10.

[0137] R １１ The number of carbon atoms in the alkyl group may be 1 to 20, preferably 1 to 15, more preferably 1 to 12, even more preferably 1 to 10, even more preferably 1 to 8, especially preferably 1 to 6, even more preferably 1 to 3, particularly preferably 1 or 2, and most preferably 1. Also, the above R １１ The alkyl group is preferably composed only of primary, secondary, and tertiary carbon atoms, and is particularly preferably composed only of primary and secondary carbon atoms. That is, R １１ The preferred groups are methyl, ethyl, n-propyl, and isopropyl, with methyl being the most preferred.

[0138] In general formula (1), R ２ and R ５ In one preferred embodiment, at least one of these is a group represented by the general formula: -X-A, where A is -COOM.

[0139] As for fluorine-free anionic surfactants, see formula (1-0A): (In the formula, R １Ａ ~R ５Ａ is H, a monovalent hydrocarbon group which may contain an ester group between carbon atoms, or general formula: -X Ａ - The group is represented by A. However, R ２Ａ and R ５Ａ At least one of them is a general formula: -X Ａ - Represents the group indicated by A. X ＡIn each occurrence, the divalent hydrocarbon group, formula: -N(R) is the same or different. ６Ａ )-R ７Ａ - (R ６Ａ is H or -CH ２ COOM (M is as described below), R ７Ａ A is a group represented by a divalent hydrocarbon group, or a bond; A is the same or different in each occurrence, -COOM (M is H, a metal atom, NR ７ ４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium, R ７ (is H or an organic group); R １Ａ ~R ５Ａ Any two of these may bond with each other to form a ring. Other examples include surfactants (1-0A) represented by ).

[0140] In general formula (1-0A), R １Ａ ~R ５Ａ In this, the monovalent hydrocarbon group, which may contain an ester group between carbon atoms, preferably has 1 to 50 carbon atoms, and more preferably 5 to 20 carbon atoms. １Ａ ~R ５Ａ Any two of these may bond to each other to form a ring. Among the monovalent hydrocarbon groups that may contain an ester group between the carbon atoms, alkyl groups are preferred. In the formula, X Ａ In this, the number of carbon atoms in the divalent hydrocarbon group is preferably 1 to 50, and more preferably 5 to 20. Examples of the above-mentioned divalent hydrocarbon group include alkylene groups and alkanediyl groups, with alkylene groups being preferred.

[0141] In general formula (1-0A), R ２Ａ and R ５Ａ Any one of the above general formulas: -X Ａ - Preferably the group is represented by A, R ２Ａ The above general formula is: -X Ａ It is more preferable that the group is represented by -A.

[0142] In the general formula (1-0A), a preferred embodiment is R ２Ａ However, the general formula is: -XＡ - The group represented by A, R １Ａ , R ３Ａ , R ４Ａ and R ５Ａ This is the mode in which H is present. In this case, X Ａ It is preferable that the bond is a C1-C5 alkylene group.

[0143] In the general formula (1-0A), a preferred embodiment is R ２Ａ However, the general formula is: -X Ａ - The group represented by A, R １Ａ and R ３Ａ ga-Y Ａ -R ６ It is a group represented by Y Ａ In each occurrence, they are identical or different, -COO-, -OCO-, or a combination, R ６ In each occurrence, R is the same or different alkyl group having one or more carbon atoms. ４Ａ and R ５Ａ It is preferable that it is H.

[0144] Examples of surfactants represented by the general formula (1-0A) include glutaric acid or its salts, adipic acid or its salts, pimelic acid or its salts, suberic acid or its salts, azelaic acid or its salts, sebacic acid or its salts, etc. Furthermore, the surfactant represented by the general formula (1-0A) may also be a two-chain, two-hydrophilic synthetic surfactant. Examples of gemini-type surfactants include GeminiSurf (Chukyo Oil & Fat Co., Ltd.), Gemsurf α142 (12 carbon atoms, lauryl group), Gemsurf α102 (10 carbon atoms), Gemsurf α182 (14 carbon atoms), etc.

[0145] In the general formula (1-0A), a preferred embodiment is R １Ａ ga-Y Ａ -R ６ It is a group represented by Y Ａ is a bonding hand, R ６ R is an alkyl group having 1 or more carbon atoms (preferably an alkylene group having 6 to 20 carbon atoms), ２Ａ , R ３Ａ , R ４Ａ and R ５Ａ H is XＡ However, the formula is: -N(R ６Ａ )-R ７Ａ - (R ６Ａ is H or -CH ２ COOM (M is as described above), R ７Ａ This embodiment is characterized by a group represented by an alkylene group (preferably a methylene group) having 1 to 5 carbon atoms. An example of a surfactant in this embodiment is lauryl hymine dicarboxylic acid.

[0146] Other examples of fluorine-free anionic surfactants include fluorine-free anionic surfactants having one or more carbonyl groups (excluding carbonyl groups in carboxyl groups). Furthermore, fluorine-free anionic surfactants having one or more carbonyl groups (excluding carbonyl groups in carboxyl groups) that have been subjected to radical treatment or oxidation treatment can also be used. The above radical treatment is any treatment that generates radicals in the fluorine-free anionic surfactant having one or more carbonyl groups (excluding carbonyl groups in carboxyl groups). For example, this treatment involves adding deionized water and a fluorine-free anionic surfactant to a reactor, sealing the reactor, purging the system with nitrogen, raising the temperature and pressure of the reactor, adding a polymerization initiator, stirring for a certain period of time, then depressurizing the reactor to atmospheric pressure and cooling it. The above oxidation treatment is a process in which an oxidizing agent is added to a fluorine-free anionic surfactant having one or more carbonyl groups (excluding carbonyl groups in carboxyl groups). Examples of oxidizing agents include oxygen, ozone, hydrogen peroxide, manganese(IV) oxide, potassium permanganate, potassium dichromate, nitric acid, and sulfur dioxide. To accelerate the radical treatment or oxidation treatment, the radical treatment or oxidation treatment may be carried out in an aqueous solution with adjusted pH. The pH of the aqueous solution for the radical treatment or oxidation treatment is preferably less than 7, and the pH of the aqueous solution can be adjusted using sulfuric acid, nitric acid, hydrochloric acid, etc.

[0147] As a fluorine-free anionic surfactant having one or more of the above carbonyl groups (excluding carbonyl groups in carboxyl groups), the formula is: R Ｘ -XＸ (In the formula, R Ｘ X is a fluorine-free organic group having 1 to 2000 carbon atoms and having one or more carbonyl groups (excluding carbonyl groups in carboxyl groups), and Ｘ is, -OSO ３ X Ｘ１ , -COOX Ｘ１ or -SO ３ X Ｘ１ (X Ｘ１ H, metal atoms, NR Ｘ１ ４ , imidazolium which may have substituents, pyridinium which may have substituents, or phosphonium which may have substituents, Ｘ１ R is H or an organic group, and may be the same or different. A surfactant represented by )) is preferred. Ｘ The carbon number is preferably 500 or less, more preferably 100 or less, even more preferably 50 or less, and even more preferably 30 or less. Ｘ１ An alkyl group is preferred as the organic group. Ｘ１ Preferably, the group is H or an organic group having 1 to 10 carbon atoms, more preferably H or an organic group having 1 to 4 carbon atoms, and even more preferably H or an alkyl group having 1 to 4 carbon atoms.

[0148] Examples of fluorine-free anionic surfactants include the following formula (a): (In the formula, R １ａ R is a linear or branched alkyl group having one or more carbon atoms, or a cyclic alkyl group having three or more carbon atoms, and the hydrogen atoms bonded to the carbon atoms may be substituted with a monovalent organic group containing a hydroxyl group or an ester bond. If there are two or more carbon atoms, it may contain a carbonyl group, and if there are three or more carbon atoms, it may contain a monovalent or divalent heterocycle or form a ring. ２ａ and R ３ａ These are independently single or divalent linking groups. １ａ , R ２ａ and R ３ａ X has a total of 6 or more carbon atoms. ａ H, metal atoms, NR ４ａ ４, imidazolium which may have substituents, pyridinium which may have substituents, or phosphonium which may have substituents, ４ａ R is either H or an organic group, and may be the same or different. １ａ , R ２ａ and R ３ａ Any two of these may bond with each other to form a ring. ) A surfactant represented by formula (a), and formula (b) below: (In the formula, R １ｂ R is a linear or branched alkyl group having 1 or more carbon atoms, which may have substituents, or a cyclic alkyl group having 3 or more carbon atoms, which may have substituents. If the number of carbon atoms is 3 or more, it may include a monovalent or divalent heterocycle or form a ring. ２ｂ and R ４ｂ R is independently either H or a substituent. ３ｂ is an alkylene group having 1 to 10 carbon atoms, which may have substituents. n is an integer of 1 or more. p and q are independently integers of 0 or more. X ｂ H, metal atoms, NR ５ｂ ４ , imidazolium which may have substituents, pyridinium which may have substituents, or phosphonium which may have substituents, ５ｂ R is either H or an organic group, and may be the same or different. １ｂ , R ２ｂ , R ３ｂ and R ４ｂ Any two of them may bond to each other to form a ring. L is a single bond, -CO ２ -B-*, -OCO-B-*, -CONR ６ｂ -B-*, -NR ６ｂ CO-B-*, or -CO- (however, -CO ２ -B-, -OCO-B-, -CONR ６ｂ -B-, -NR ６ CO-B- (excluding the carbonyl group contained therein), where B is a single bond or an alkylene group having 1 to 10 carbon atoms which may have substituents, and R ６ｂ is an alkyl group having 1 to 4 carbon atoms, which may have H or a substituent. * is -OSO in the formula. ３ Xｂ This refers to the side that binds to the surfactant (b), shown in the following formula (c): (In the formula, R １ｃ R is a linear or branched alkyl group having one or more carbon atoms, or a cyclic alkyl group having three or more carbon atoms, and the hydrogen atoms bonded to the carbon atoms may be substituted with a monovalent organic group containing a hydroxyl group or an ester bond. If there are two or more carbon atoms, it may contain a carbonyl group, and if there are three or more carbon atoms, it may contain a monovalent or divalent heterocycle or form a ring. ２ｃ and R ３ｃ These are independently single or divalent linking groups. １ｃ , R ２ｃ and R ３ｃ The total number of carbon atoms is 5 or more. ｃ is, -COOX ｃ or -SO ３ X ｃ (X ｃ H, metal atoms, NR ４ｃ ４ , imidazolium which may have substituents, pyridinium which may have substituents, or phosphonium which may have substituents, ４ｃ R is either H or an organic group, and may be the same or different. １ｃ , R ２ｃ and R ３ｃ Any two of these may bond with each other to form a ring.) A surfactant represented by formula (c), and the following formula (d): (In the formula, R １ｄ R is a linear or branched alkyl group having 1 or more carbon atoms, which may have substituents, or a cyclic alkyl group having 3 or more carbon atoms, which may have substituents. If the number of carbon atoms is 3 or more, it may include a monovalent or divalent heterocycle or form a ring. ２ｄ and R ４ｄ R is independently either H or a substituent. ３ｄ is an alkylene group having 1 to 10 carbon atoms, which may have substituents. n is an integer of 1 or more. p and q are independently integers of 0 or more. A ｄ is, -SO ３ X ｄ or -COOX ｄ (Xｄ H, metal atoms, NR ５ｄ ４ , imidazolium which may have substituents, pyridinium which may have substituents, or phosphonium which may have substituents, ５ｄ R is either H or an organic group, and may be the same or different. １ｄ , R ２ｄ , R ３ｄ and R ４ｄ Any two of them may bond to each other to form a ring. L is a single bond, -CO ２ -B-*, -OCO-B-*, -CONR ６ｄ -B-*, -NR ６ｄ CO-B-*, or -CO- (however, -CO ２ -B-, -OCO-B-, -CONR ６ｄ -B-, -NR ６ｄ CO-B- (excluding the carbonyl group contained therein), where B is a single bond or an alkylene group having 1 to 10 carbon atoms which may have substituents, and R ６ｄ is an alkyl group having 1 to 4 carbon atoms, which may have H or a substituent. * is A in the formula. ｄ This refers to the side that binds to (d). At least one selected from the group consisting of surfactants (d) represented by (d) is more preferable.

[0149] Let's explain surfactants (c).

[0150] In formula (c), R １ｃ This is a linear or branched alkyl group having one or more carbon atoms, or a cyclic alkyl group having three or more carbon atoms. If the alkyl group has three or more carbon atoms, it may contain a carbonyl group (-C(=O)-) between two carbon atoms. Furthermore, if the alkyl group has two or more carbon atoms, it may contain the carbonyl group at the end of the alkyl group. That is, CH ３Acyl groups such as the acetyl group represented by -C(=O)- are also included in the alkyl groups mentioned above. Furthermore, if the alkyl group has three or more carbon atoms, it may include a monovalent or divalent heterocycle, or it may form a ring. As the heterocycle, an unsaturated heterocycle is preferred, and an oxygen-containing unsaturated heterocycle is more preferred, such as a furan ring. R １ｃ In this configuration, a divalent heterocycle may be inserted between two carbon atoms, or a divalent heterocycle may be located at the terminal and bonded to -C(=O)-, or a monovalent heterocycle may be located at the terminal of the alkyl group.

[0151] In this disclosure, the "number of carbon atoms" of the alkyl group includes the number of carbon atoms constituting the carbonyl group and the number of carbon atoms constituting the heterocycle. For example, CH ３ -C(=O)-CH ２ The group indicated by - has 3 carbon atoms, CH ３ -C (=O) -C ２ H ４ -C (=O) -C ２ H ４ The group indicated by - has 7 carbon atoms, CH ３ The group represented by -C(=O)- has two carbon atoms.

[0152] The alkyl group described above may have hydrogen atoms bonded to carbon atoms substituted with functional groups, for example, with a hydroxyl group (-OH) or a monovalent organic group containing an ester bond, but it is preferable that it is not substituted with any functional group. The monovalent organic group containing an ester bond described above has the formula: -O-C(=O)-R １０１ｃ (In the formula, R １０１ｃ Examples of groups are those represented by alkyl groups. The alkyl group may have 75% or less of the hydrogen atoms bonded to the carbon atom substituted with halogen atoms, 50% or less substituted with halogen atoms, or 25% or less substituted with halogen atoms, but it is preferable that it is a non-halogenated alkyl group that does not contain halogen atoms such as fluorine atoms or chlorine atoms.

[0153] In formula (c), R ２ｃ and R ３ｃThese are independently single or divalent linking groups. ２ｃ and R ３ｃ Preferably, each of these is independently a single bond, a linear or branched alkylene group having 1 or more carbon atoms, or a cyclic alkylene group having 3 or more carbon atoms. ２ｃ and R ３ｃ The alkylene group constituting the above preferably does not contain a carbonyl group.

[0154] The alkylene group described above may have hydrogen atoms bonded to carbon atoms substituted with functional groups, for example, with a hydroxyl group (-OH) or a monovalent organic group containing an ester bond, but it is preferable that it is not substituted with any functional group. The monovalent organic group containing the ester bond described above has the formula: -O-C(=O)-R １０２ｃ (In the formula, R １０２ｃ Examples of groups are those represented by alkyl groups. The alkylene group may have 75% or less of the hydrogen atoms bonded to the carbon atom substituted with halogen atoms, 50% or less substituted with halogen atoms, or 25% or less substituted with halogen atoms, but it is preferable that it is a non-halogenated alkylene group that does not contain halogen atoms such as fluorine atoms or chlorine atoms.

[0155] R １ｃ , R ２ｃ and R ３ｃ The total number of carbon atoms is 5 or more. Preferably, the total number of carbon atoms is 7 or more, more preferably 9 or more, preferably 20 or less, more preferably 18 or less, and even more preferably 15 or less. １ｃ , R ２ｃ and R ３ｃ Any two of them may be joined together to form a ring.

[0156] In formula (c), in the formula, A ｃ is, -COOX ｃ or -SO ３ X ｃ (X ｃ H, metal atoms, NR ４ｃ ４, imidazolium which may have substituents, pyridinium which may have substituents, or phosphonium which may have substituents, ４ｃ (This is H or an organic group, and may be the same or different.) A ｃ As for, -COOX ｃ This is preferable. ４ｃ Alkyl alkyl groups are preferred as the organic groups in R. ４ｃ Preferably, the metal atom is H or an organic group having 1 to 10 carbon atoms, more preferably H or an organic group having 1 to 4 carbon atoms, and even more preferably H or an alkyl group having 1 to 4 carbon atoms. Examples of the metal atoms include monovalent and divalent metal atoms, such as alkali metals (Group 1) and alkaline earth metals (Group 2), with Na, K, or Li being preferred. ｃ Examples include H, alkali metals (Group 1), alkaline earth metals (Group 2), or NR ４ｃ ４ Preferably, H, Na, K, Li or NH ４ More preferable and more easily soluble in water, Na, K, or NH ４ More preferably, Na or NH ４ This is particularly preferable and easy to remove, NH ４ This is the most preferable. X ｃ NH ４ As a result, the surfactant exhibits excellent solubility in aqueous media, and metal components are less likely to remain in the polymer or the final product.

[0157] Let's explain surfactants (d).

[0158] In formula (d), R １ｄ This is a linear or branched alkyl group having one or more carbon atoms, which may have substituents, or a cyclic alkyl group having three or more carbon atoms, which may have substituents. If the alkyl group has three or more carbon atoms, it may include a monovalent or divalent heterocycle, or it may form a ring. As the heterocycle, an unsaturated heterocycle is preferred, and an oxygen-containing unsaturated heterocycle is more preferred, such as a furan ring. １ｄIn this configuration, a divalent heterocycle may be inserted between two carbon atoms, or a divalent heterocycle may be located at the terminal and bonded to -C(=O)-, or a monovalent heterocycle may be located at the terminal of the alkyl group.

[0159] In this disclosure, the "number of carbon atoms" of the alkyl group includes the number of carbon atoms constituting the heterocycle.

[0160] R １ｄ The substituents that the alkyl group may have are preferably halogen atoms, linear or branched alkyl groups having 1 to 10 carbon atoms, or cyclic alkyl groups having 3 to 10 carbon atoms, and hydroxyl groups, with methyl groups and ethyl groups being particularly preferred.

[0161] R １ｄ The alkyl group described above preferably does not contain a carbonyl group. The alkyl group may have 75% or less of the hydrogen atoms bonded to the carbon atom substituted with halogen atoms, 50% or less substituted with halogen atoms, or 25% or less substituted with halogen atoms, but it is preferable that it is a non-halogenated alkyl group that does not contain halogen atoms such as fluorine atoms or chlorine atoms. The alkyl group may preferably have no substituents whatsoever.

[0162] R １ｄ Preferably, the alkyl group is a linear or branched alkyl group having 1 to 10 carbon atoms, which may have substituents, or a cyclic alkyl group having 3 to 10 carbon atoms, which may have substituents; more preferably, a linear or branched alkyl group having 1 to 10 carbon atoms that does not contain a carbonyl group, or a cyclic alkyl group having 3 to 10 carbon atoms that does not contain a carbonyl group; even more preferably, a linear or branched alkyl group having 1 to 10 carbon atoms without substituents; and even more preferably, a linear or branched alkyl group having 1 to 3 carbon atoms without substituents, and a methyl group (-CH ３ ) or ethyl group (-C ２ H ５ ) is particularly preferred, and a methyl group (-CH ３ ) is the most preferable.

[0163] In formula (d), R ２ｄ and R４ｄ These are independently H or substituents. Multiple R ２ｄ and R ４ｄ These may be the same or different.

[0164] R ２ｄ and R ４ｄ The substituents mentioned above are preferably halogen atoms, linear or branched alkyl groups having 1 to 10 carbon atoms, or cyclic alkyl groups having 3 to 10 carbon atoms, or hydroxyl groups, with methyl groups and ethyl groups being particularly preferred.

[0165] R ２ｄ and R ４ｄ The alkyl group described above preferably does not contain a carbonyl group. The alkyl group may have 75% or less of the hydrogen atoms bonded to the carbon atom substituted with halogen atoms, 50% or less substituted with halogen atoms, or 25% or less substituted with halogen atoms, but it is preferable that it is a non-halogenated alkyl group that does not contain halogen atoms such as fluorine atoms or chlorine atoms. The alkyl group may preferably have no substituents whatsoever.

[0166] R ２ｄ and R ４ｄ The alkyl group described above is preferably a linear or branched alkyl group having 1 to 10 carbon atoms that does not contain a carbonyl group, or a cyclic alkyl group having 3 to 10 carbon atoms that does not contain a carbonyl group, more preferably a linear or branched alkyl group having 1 to 10 carbon atoms that does not contain a carbonyl group, and even more preferably a linear or branched alkyl group having 1 to 3 carbon atoms that does not have substituents, and a methyl group (-CH ３ ) or ethyl group (-C ２ H ５ ) is particularly preferable.

[0167] R ２ｄ and R ４ｄ Preferably, the alkyl group is a linear or branched alkyl group having 1 to 10 carbon atoms that does not contain H or a carbonyl group, more preferably a linear or branched alkyl group having 1 to 3 carbon atoms that does not contain H or a substituent, and H, methyl group (-CH ３ ) or ethyl group (-C ２ H５ ) is even more preferable, and H is particularly preferable.

[0168] In formula (d), R ３ｄ R is an alkylene group having 1 to 10 carbon atoms, which may have substituents. ３ｄ If there are multiple instances of this, they may be identical or different.

[0169] The alkylene group described above preferably does not contain a carbonyl group. The alkylene group may have 75% or less of the hydrogen atoms bonded to the carbon atom substituted with halogen atoms, 50% or less substituted with halogen atoms, or 25% or less substituted with halogen atoms, but it is preferable that it is a non-halogenated alkyl group that does not contain halogen atoms such as fluorine atoms or chlorine atoms. The alkylene group described above preferably does not have any substituents.

[0170] The alkylene group is preferably a linear or branched alkylene group having 1 to 10 carbon atoms, which may have substituents, or a cyclic alkylene group having 3 to 10 carbon atoms, which may have substituents; preferably a linear or branched alkylene group having 1 to 10 carbon atoms that does not contain a carbonyl group; more preferably a linear or branched alkylene group having 1 to 10 carbon atoms that does not contain a substituent; and more preferably a methylene group (-CH ２ -), ethylene group (-C ２ H ４ -), isopropylene group (-CH(CH ３ )CH ２ -) or propylene group (-C) ３ H ６ -) is even more preferable.

[0171] R １ｄ , R ２ｄ , R ３ｄ and R ４ｄ Any two of them may be joined together to form a ring.

[0172] In formula (d), n is an integer greater than or equal to 1. n is preferably an integer between 1 and 40, more preferably between 1 and 30, and even more preferably between 5 and 25.

[0173] In formula (d), p and q are independently integers of 0 or greater. p is preferably an integer between 0 and 10, and more preferably 0 or 1. q is preferably an integer between 0 and 10, and more preferably an integer between 0 and 5.

[0174] It is preferable that n, p, and q are integers whose sum is 6 or greater. It is more preferable that the sum of n, p, and q is an integer of 8 or greater. It is also preferable that the sum of n, p, and q is an integer of 60 or less, more preferably an integer of 50 or less, and even more preferably an integer of 40 or less.

[0175] In formula (d), A ｄ is, -SO ３ X ｄ or -COOX ｄ (X ｄ H, metal atoms, NR ５ｄ ４ , imidazolium which may have substituents, pyridinium which may have substituents, or phosphonium which may have substituents, ５ｄ (This is H or an organic group, and may be the same or different.) A ｄ As for, -COOX ｄ This is preferable. ５ｄ Alkyl alkyl groups are preferred as the organic groups in R. ５ｄ Preferably, the metal atom is H or an organic group having 1 to 10 carbon atoms, more preferably H or an organic group having 1 to 4 carbon atoms, and even more preferably H or an alkyl group having 1 to 4 carbon atoms. Examples of the metal atoms include monovalent and divalent metal atoms, such as alkali metals (Group 1) and alkaline earth metals (Group 2), with Na, K, or Li being preferred. ｄ is a metal atom or NR ５ｄ ４ (R ５ｄ (As stated above) may be X ｄ Examples include H, alkali metals (Group 1), alkaline earth metals (Group 2), or NR ５ｄ ４ Preferably, H, Na, K, Li or NH ４ More preferable and more easily soluble in water, Na, K, or NH ４More preferably, Na or NH ４ This is particularly preferable and easy to remove, NH ４ This is the most preferable. X ｄ NH ４ As a result, the surfactant exhibits excellent solubility in aqueous media, and metal components are less likely to remain in the polymer or the final product.

[0176] In equation (d), L is a single bond, -CO ２ -B-*, -OCO-B-*, -CONR ６ｄ -B-*, -NR ６ｄ CO-B-*, or -CO- (however, -CO ２ -B-, -OCO-B-, -CONR ６ｄ -B-, -NR ６ｄ (Excluding the carbonyl group contained in CO-B-), where B is a single bond or an alkylene group having 1 to 10 carbon atoms which may have substituents, and R ６ｄ is an alkyl group having 1 to 4 carbon atoms, which may have H or substituents. The alkylene group is more preferably having 1 to 5 carbon atoms. Also, the above R ６ｄ It is more preferably H or a methyl group. * is A in the formula ｄ This refers to the side that connects to it.

[0177] L is preferably a single bond.

[0178] As a fluorine-free anionic surfactant, see formula I: R-(XZ) ｎ (I) (wherein R is a hydrophobic hydrocarbon moiety containing one or more saturated or unsaturated, acyclic or cyclic aliphatic groups. CH in one or more aliphatic groups) ３ ,CH ２ and CH for the total of CH groups ３ The total percentage of the groups is at least about 70%, and the hydrophobic portion does not contain siloxane units. Each X may be the same or different and represents an ionic hydrophilic portion. Each Z may be the same or different and represents one or more counterions of the ionic hydrophilic portion. n is 1 to 3. Compound I, shown in (), is also an example.

[0179] Compound I exhibits low reactivity with polymerization initiators and / or growing fluoropolymer radicals in the polymerization of fluoromonomers.

[0180] Compound I is given by the following formula: (In the formula, Y ＋ It is preferable that the substitution moiety is represented by ( ), which is hydrogen, ammonium, quaternary ammonium, nitrogen heterocycle, alkali metal, or alkaline earth element.

[0181] Compound I is given by the following formula II: (In the formula, R ２’ and R ２’’ R is a saturated or unsaturated, acyclic or cyclic aliphatic group having 4 to 16 carbon atoms, and is either the same or different. ２’ and R ２’’ CH in the base ３ ,CH ２ and CH for the total of CH groups ３ The percentage of the sum of the bases is at least about 70%, or R ２’ and R ２’’ These can bond together to form saturated or unsaturated aliphatic rings that may contain ether or ester bonds. However, the CH in the ring ３ ,CH ２ and CH for the total of CH groups ３ The percentage of the sum of the bases is at least about 70%. １ is hydrogen, methoxy, ethoxy, or phenoxy. ＋ It is preferably compound II represented by ( ).

[0182] As compound II, the following compounds are preferred, for example. Y in the above formula ＋ This may be hydrogen, ammonium, or an alkali metal.

[0183] Compound I is given by the following formula III: (In the formula, R ３ , R ４’ , and R ４’’R is a saturated or unsaturated, acyclic or cyclic aliphatic group having hydrogen or 4 to 16 carbon atoms, and is either the same or different. ３ , R ４’ , and R ４’’ CH at the base ３ ,CH ２ And with respect to the total of CH groups ３ The total percentage of is at least about 70%. However, R ３ , R ４’ , and R ４’’ At least one of them is not hydrogen, R ４’ and R ４’’ If R is hydrogen, ３ It is not hydrogen, but R ３ If R is hydrogen, ４’ and R ４’’ It is not hydrogen. Y ＋ It is also preferable that it is compound III represented by ( ).

[0184] For example, the following compounds are preferred as compound III. Y in the above formula ＋ This may be hydrogen, ammonium, or an alkali metal.

[0185] In the manufacturing method of this disclosure, two or more fluorine-free anionic surfactants may be used simultaneously.

[0186] Furthermore, examples of fluorine-free anionic surfactants include the surfactant (1) described above, a fluorine-free anionic surfactant having one or more carbonyl groups (excluding carbonyl groups in carboxyl groups), or a specific fluorine-free anionic surfactant obtained by radical treatment or oxidation treatment of a fluorine-free anionic surfactant having one or more carbonyl groups (excluding carbonyl groups in carboxyl groups). The specific fluorine-free anionic surfactant is preferably a fluorine-free anionic surfactant obtained by radical treatment or oxidation treatment of a fluorine-free anionic surfactant having one or more carbonyl groups (excluding carbonyl groups in carboxyl groups), or a fluorine-free anionic surfactant obtained by radical treatment or oxidation treatment of a fluorine-free anionic surfactant having one or more carbonyl groups (excluding carbonyl groups in carboxyl groups). By using specific fluorine-free anionic surfactants that have undergone radical treatment or oxidation treatment, primary particles with a small average primary particle size and aspect ratio can be easily obtained. This allows for smooth polymerization of monomers in an aqueous medium, and facilitates the production of polymers.

[0187] Radical treatment refers to any treatment in which a radical is applied to a fluorine-free anionic surfactant. For example, this treatment involves adding deionized water and a fluorine-free anionic surfactant to a reactor, sealing the reactor, purging the system with nitrogen, raising the temperature and pressure of the reactor, adding a polymerization initiator, stirring for a certain period of time, then depressurizing the reactor to atmospheric pressure and cooling it. The oxidation treatment refers to a treatment in which an oxidizing agent is applied to a fluorine-free anionic surfactant. Examples of oxidizing agents include oxygen, ozone, hydrogen peroxide, manganese(IV) oxide, potassium permanganate, potassium dichromate, nitric acid, and sulfur dioxide.

[0188] The above-mentioned specific fluorine-free anionic surfactant is preferably at least one selected from the group consisting of the surfactant (1) represented by the general formula (1), the surfactant (a) represented by the formula (a), the surfactant (b) represented by the formula (b), the surfactant (c) represented by the formula (c), the surfactant (d) represented by the formula (d), and surfactants obtained by radical treatment or oxidation treatment of these surfactants (a) to (d). More preferably, at least one selected from the group consisting of the surfactant (a) represented by the formula (a), the surfactant (b) represented by the formula (b), the surfactant (c) represented by the formula (c), the surfactant (d) represented by the formula (d), and surfactants obtained by radical treatment or oxidation treatment of these surfactants (a) to (d).

[0189] In the manufacturing method of this disclosure, the fluorine-free anionic surfactant used is preferably a carboxylic acid-type fluorine-free anionic surfactant. Carboxylic acid-type fluorine-free anionic surfactants tend to have a shorter coagulation completion time compared to sulfate ester-based surfactants. However, according to the manufacturing method of this disclosure, even when a carboxylic acid-type hydrocarbon surfactant is used, an aqueous dispersion with a long coagulation completion time can be produced. In other words, the manufacturing method of this disclosure is particularly suitable when the fluorine-free anionic surfactant is a carboxylic acid-type fluorine-free anionic surfactant. The carboxylic acid-type fluorine-free anionic surfactant is usually an anionic hydrocarbon surfactant having a hydrophilic portion of a carboxylate salt and a hydrophobic portion which is a long-chain hydrocarbon portion such as an alkyl group. Specifically, it is not limited to those having a carboxyl group (-COOH) or a group in which the hydrogen atoms of the carboxyl group are substituted with inorganic cations (e.g., metal atoms, ammonium, etc.). For example, from the above-mentioned fluorine-free anionic surfactants, a fluorine-free anionic surfactant having a carboxyl group or a group in which the hydrogen atoms of the carboxyl group are substituted with inorganic cations can be used.

[0190] The fluorine-free anionic surfactant may be an aliphatic carboxylic acid-type fluorine-free anionic surfactant, or a carboxylic acid-type fluorine-free anionic surfactant other than an aliphatic type. In this disclosure, "aliphatic carboxylic acid-type fluorine-free anionic surfactant" means a carboxylic acid-type fluorine-free anionic surfactant that does not contain a carbonyl group (excluding carbonyl groups in carboxyl groups and ester groups). The ester group refers to a group represented by -COO- or -OCO-.

[0191] As a carboxylic acid-type fluorine-free anionic surfactant, for example, a fluorine-free anionic surfactant having a carboxyl group or a group in which the hydrogen atoms of a carboxyl group are substituted with an inorganic cation can be used from among the fluorine-free anionic surfactants described above.

[0192] As a carboxylic acid-type fluorine-free anionic surfactant, surfactant (1), the above formula: R ６ｚ (-L-M) ２ Anionic surfactants represented by the above formula: R ７ｚ (-L-M) ３ It is preferable that the anionic surfactant represented by is at least one selected from the group consisting of those having a carboxyl group (-COOH) or a group in which the hydrogen atom of the carboxyl group is substituted with an inorganic cation (e.g., a metal atom, ammonium, etc.), surfactants (1-0A), and surfactants that have been subjected to radical treatment or oxidation treatment. The above carboxylic acid-type fluorine-free anionic surfactant may be used individually or as a mixture of two or more.

[0193] As carboxylic acid-type fluorine-free anionic surfactants, at least one selected from the group consisting of lauric acid, capric acid, myristic acid, pentadecyl acid, palmitic acid, and salts thereof, and compounds obtained by radical treatment or oxidation treatment of these compounds is particularly preferred; at least one selected from the group consisting of lauric acid and salts thereof, and compounds obtained by radical treatment or oxidation treatment of these compounds is more preferred; at least one selected from the group consisting of salts of lauric acid and compounds obtained by radical treatment or oxidation treatment thereof is even more preferred; and at least one selected from the group consisting of sodium laurate and compounds obtained by radical treatment or oxidation treatment thereof is even more preferred. As for the salts, the hydrogen of the carboxyl group is a metal atom of formula M described above, NR １０１ ４ Examples include, but are not limited to, imidazolium which may have substituents, pyridinium which may have substituents, or phosphonium which may have substituents.

[0194] (Additives) Additives may be used in the polymerization described above. Examples of such additives include buffers, pH adjusters, stabilizing agents, and dispersion stabilizers.

[0195] Preferred stabilizing agents include paraffin wax, fluorinated oils, fluorinated solvents, and silicone oils. Stabilizing agents may be used individually or in combination of two or more. Paraffin wax is more preferred as a stabilizing agent. Paraffin wax may be liquid, semi-solid, or solid at room temperature, but saturated hydrocarbons with 12 or more carbon atoms are preferred. The melting point of paraffin wax is usually preferably 40 to 65°C, and more preferably 50 to 65°C.

[0196] The amount of stabilizing agent used is preferably 0.1 to 12% by mass, and more preferably 0.1 to 8% by mass, based on the mass of the aqueous medium used. It is desirable that the stabilizing agent is sufficiently hydrophobic and completely separates from the aqueous dispersion after polymerization so as not to become a contaminating component.

[0197] (Water-soluble fluoropolymer) In the first polymerization of the manufacturing method of the present disclosure, an aqueous solution containing a water-soluble fluoropolymer is obtained.

[0198] In one embodiment, the water-soluble fluoropolymer has a melting point. The melting point of the water-soluble fluoropolymer is preferably 250°C or higher, more preferably 270°C or higher, even more preferably 280°C or higher, still more preferably 290°C or higher, preferably 330°C or lower, and more preferably 320°C or lower.

[0199] In one embodiment, the water-soluble fluoropolymer has a glass transition temperature. The glass transition temperature of the water-soluble fluoropolymer is preferably 10°C or lower, more preferably 5°C or lower, even more preferably 0°C or lower, preferably -50°C or higher, more preferably -45°C or higher, and even more preferably -40°C or higher.

[0200] In one embodiment, the water-soluble fluoropolymer has no melting point. In one embodiment, the water-soluble fluoropolymer is a fluoropolymer having a melting point within the above range, or a fluoropolymer having a glass transition temperature within the above range and having no melting point.

[0201] The melting point of water-soluble fluoropolymers can be measured using a differential thermogravimetric analyzer (TG / DTA). The glass transition temperature of water-soluble fluoropolymers can be measured using differential scanning calorimetry (DSC).

[0202] In one embodiment of the manufacturing method of this disclosure, a water-soluble fluoropolymer is formed when the mass of the fluoropolymer produced by polymerization reaches at least 3% by mass relative to the mass of the aqueous medium. Preferably, the melting point or glass transition temperature of the water-soluble fluoropolymer produced when the mass of the water-soluble fluoropolymer produced by polymerization reaches 3% by mass relative to the mass of the aqueous medium is within the above-mentioned numerical range.

[0203] In one embodiment, at least TFE is used as the fluoromonomer in the first polymerization. In one embodiment, TFE, or a combination of TFE and a fluoromonomer other than TFE, is used in the first polymerization. In one embodiment, TFE, or a combination of TFE and a fluoroalkyl vinyl ether, is used in the first polymerization. Examples of fluoromonomers and fluoroalkyl vinyl ethers are described later. The fluoroalkyl vinyl ether used in the first polymerization is preferably at least one selected from the group consisting of perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether), and perfluoro(propyl vinyl ether), more preferably at least one selected from the group consisting of perfluoro(methyl vinyl ether) and perfluoro(propyl vinyl ether), and even more preferably perfluoro(methyl vinyl ether).

[0204] In one embodiment, the water-soluble fluoropolymer contains at least TFE units. In one embodiment, the water-soluble fluoropolymer contains TFE units, or TFE units and fluoromonomer units other than TFE units. In one embodiment, the water-soluble fluoropolymer contains TFE units, or TFE units and fluoroalkyl vinyl ether units. In one embodiment, the water-soluble fluoropolymer contains 99 mol% or more of TFE units, or contains 80 to 40 mol% of TFE units and 20 to 60 mol% of fluoroalkyl vinyl ether units.

[0205] (Polymerization) In the manufacturing method of this disclosure, the polymerization reaction usually proceeds with the fluoromonomer emulsified in an aqueous medium. Therefore, the final aqueous dispersion contains fluororesin particles stably dispersed in the aqueous medium.

[0206] In the manufacturing method of this disclosure, polymerization is carried out by charging an aqueous medium, a fluoromonomer, and other additives as needed into a reactor, stirring the contents of the reactor, maintaining the reactor at a predetermined polymerization temperature, and then adding a predetermined amount of polymerization initiator to start the polymerization reaction. After the start of the polymerization reaction, monomers, polymerization initiators, chain transfer agents, etc., may be added as needed.

[0207] Typically, the polymerization temperature is 5 to 120°C, and the polymerization pressure is 0.05 to 10 MPaG. The polymerization temperature and pressure are appropriately determined depending on the type of monomer used, the molecular weight of the target fluororesin, and the reaction rate.

[0208] In the manufacturing method of this disclosure, the polymerization temperature may be changed during polymerization. For example, the first polymerization can be carried out at a first temperature, and the second polymerization can be carried out at a second temperature lower than the first temperature. By changing the polymerization temperature in this way, it becomes easier to adjust the polymerization rate and the amount of decomposition of the polymerization initiator.

[0209] The first temperature may be, for example, 85°C or higher and 120°C or lower. The second temperature may be 5°C or higher and less than 85°C.

[0210] In the manufacturing method of the present disclosure, the first polymerization and the second polymerization may be carried out in the same reactor or in different reactors. In one embodiment, the second polymerization is carried out in the presence of the aqueous solution obtained by the first polymerization, either without adding any new aqueous medium, or by adding an aqueous medium of less than 1% by mass of the mass of the aqueous solution obtained by the first polymerization. In one embodiment, after preparing the aqueous solution by carrying out the first polymerization, the aqueous solution obtained by the first polymerization is stirred at a stirring rate higher than that used during the first polymerization, and the second polymerization is started.

[0211] (Fluoromers) Fluoromers having at least one double bond are preferred. Examples of fluoroomers include tetrafluoroethylene [TFE], hexafluoropropylene [HFP], chlorotrifluoroethylene [CTFE], vinyl fluoride, vinylidene fluoride [VDF], trifluoroethylene, fluoroalkyl vinyl ether, fluoroalkylethylene, fluoroalkyl allyl ether, trifluoropropylene, pentafluoropropylene, trifluorobutene, tetrafluoroisobutene, hexafluoroisobutene, and general formula (100): CHX １０１ = CX １０２ Rf １０１ (In the formula, X １０１ and X １０２ In this case, one is H, the other is F, and Rf １０１ Preferably, the monomer is at least one selected from the group consisting of fluoromonomers (represented by a linear or branched fluoroalkyl group having 1 to 12 carbon atoms), fluorinated vinyl heterocyclic compounds, and monomers that provide a crosslinking site.

[0212] Examples of the above fluoroalkyl vinyl ether include General formula (110): CF ２ =CF - ORf １１１ (wherein, Rf １１１ represents a perfluoroorganic group. ) Fluoromer represented by general formula (120): CF ２ = CF - OCH ２ -Rf １２１ (wherein, Rf １２１ Fluoromers represented by perfluoroalkyl groups having 1 to 5 carbon atoms, general formula (130): CF ２ = CFOCF ２ ORf １３１ (wherein, Rf １３１ ) is a linear or branched perfluoroalkyl group having 1 to 6 carbon atoms, a cyclic perfluoroalkyl group having 5 to 6 carbon atoms, or a linear or branched perfluorooxyalkyl group having 2 to 6 carbon atoms containing 1 to 3 oxygen atoms. Fluoromers represented by ) General formula (140): CF ２ = CFO (CF ２ CF(Y１４１ )O) ｍ (CF ２ ) ｎ F (wherein, Y １４１ represents a fluorine atom or a trifluoromethyl group. m is an integer from 1 to 4. n is an integer from 1 to 4.) Fluoromers represented by the formula (150): CF ２ =CF - O - (CF ２ CFY １５１ -O) ｎ - (CFY １５２ ) ｍ -A １５１ (In the formula, Y １５１ These are fluorine atoms, chlorine atoms, and -SO ２ Represents an F group or a perfluoroalkyl group. Perfluoroalkyl groups consist of etheric oxygen and -SO ２ It may include an F element. n represents an integer from 0 to 3. n Y elements １５１ They may be the same or they may be different. １５２ is a fluorine atom, a chlorine atom, or -SO ２ F represents a base. m represents an integer from 1 to 5. m Y １５２ They may be the same or they may be different. A １５１ is, -SO ２ X １５１ , -COZ １５１ or -POZ １５２ Z １５３ It represents X １５１ is F, Cl, Br, I, -OR １５１ or -NR １５２ R １５３ It represents Z. １５１ Z １５２ and Z １５３ These are the same or different, -NR １５４ R １５５ OR １５６ Represents R １５１ , R １５２ , R １５３ , R １５４ , R １５５ and R １５６It is preferable that the group consists of at least one selected from the group comprising fluoromonomers represented by ), which may contain H, ammonium, alkali metal, fluorine atoms, alkyl groups, aryl groups, or sulfonyl-containing groups, either identically or differently.

[0213] In this disclosure, the term "perfluoroorganic group" means an organic group in which all hydrogen atoms bonded to a carbon atom are replaced with fluorine atoms. The perfluoroorganic group may have an ether oxygen atom.

[0214] As a fluoromonomer represented by general formula (110), Rf １１１ Examples of fluoromonomers include those in which the perfluoroalkyl group has 1 to 10 carbon atoms. The number of carbon atoms in the perfluoroalkyl group is preferably 1 to 5.

[0215] Examples of perfluoroorganic groups in general formula (110) include perfluoromethyl group, perfluoroethyl group, perfluoropropyl group, perfluorobutyl group, perfluoropentyl group, and perfluorohexyl group. Furthermore, as fluoromonomers represented by general formula (110), Rf １１１ Rf １１１ The formula is as follows:

[0216]

[0217] (In the formula, m represents an integer from 0 to 4.) The base Rf is represented by the following formula:

[0218] CF ３ CF ２ CF ２ - (O-CF(CF ３ ) - CF ２ ) ｎ Examples include the base represented by - (wherein n represents an integer from 1 to 4).

[0219] Among the fluoromonomers represented by general formula (110), there is general formula (160): CF ２ =CF - ORf １６１ (wherein, Rf１６１ Rf represents a perfluoroalkyl group having 1 to 10 carbon atoms. Fluoromonomers represented by Rf are preferred. １６１ It is preferable that it is a perfluoroalkyl group having 1 to 5 carbon atoms.

[0220] The fluoroalkyl vinyl ether is preferably at least one selected from the group consisting of fluoromonomers represented by general formulas (160), (130), and (140).

[0221] The fluoromonomer represented by general formula (160) is preferably at least one selected from the group consisting of perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether), and perfluoro(propyl vinyl ether), and more preferably at least one selected from the group consisting of perfluoro(methyl vinyl ether) and perfluoro(propyl vinyl ether).

[0222] As a fluoromonomer represented by general formula (130), CF ２ = CFOCF ２ OCF ３ CF ２ = CFOCF ２ OCF ２ CF ３ , and CF ２ = CFOCF ２ OCF ２ CF ２ OCF ３ It is preferable that it be at least one selected from the group consisting of the following:

[0223] Fluoromers represented by general formula (140) include CF ２ = CFOCF ２ CF (CF ３ )O(CF ２ ) ３ F, CF ２ = CFO (CF ２ CF (CF ３ )O) ２ (CF ２ ) ３ F and CF ２ = CFO (CF ２ CF (CF３ )O) ２ (CF ２ ) ２ It is preferable that it be at least one selected from the group consisting of F.

[0224] As a fluoromonomer represented by general formula (150), CF ２ = CFOCF ２ CF ２ SO ２ F, CF ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２ SO ２ F, CF ２ = CFOCF ２ CF (CF ２ CF ２ SO ２ F) OCF ２ CF ２ SO ２ F and CF ２ = CFOCF ２ CF (SO ２ F) ２ At least one selected from the group consisting of is preferred.

[0225] As a fluoromonomer represented by the general formula (100), Rf １０１ A fluoromonomer in which is a linear fluoroalkyl group is preferred, and Rf １０１ A fluoromonomer in which the linear perfluoroalkyl group is is more preferred. １０１ The number of carbon atoms is preferably 1 to 6. The fluoromonomer represented by the general formula (100) is CH ２ = CFCF ３ ,CH ２ = CFCF ２ CF ３ ,CH ２ = CFCF ２ CF ２ CF ３ ,CH ２ = CFCF ２ CF ２ CF ２ H, CH ２ = CFCF ２ CF ２CF ２ CF ３ CHF = CHCF ３ (E form), CHF=CHCF ３ (Z-isomer) is one example, and among them, CH ２ = CFCF ３ 2,3,3,3-tetrafluoropropylene, represented by [the symbol], is preferred.

[0226] Examples of fluoroalkylethylenes include those with the general formula (170): CH ２ = CH - (CF ２ ) ｎ -X １７１ (In the formula, X １７１ is H or F, and n is an integer from 3 to 10. Fluoroalkylethylene represented by ) is preferred, CH ２ = CH - C ４ F ９ , and CH ２ = CH - C ６ F １３ It is more preferable that it be at least one selected from the group consisting of the following:

[0227] Examples of the above fluoroalkyl allyl ethers include, for example, General formula (180): CF ２ = CF - CF ２ -ORf １１１ (wherein, Rf １１１ ) represents a perfluoroorganic group. Examples include fluoromonomers represented by ).

[0228] Rf of general formula (180) １１１ Rf of general formula (110) １１１ It is the same as Rf １１１ As such, a perfluoroalkyl group having 1 to 10 carbon atoms or a perfluoroalkoxyalkyl group having 1 to 10 carbon atoms is preferred. As a fluoroalkyl allyl ether represented by general formula (180), CF ２ = CF - CF ２ -O-CF ３ CF ２ = CF - CF ２ -O-C ２ F ５ CF ２ = CF - CF ２ -O-C３ F ７ , and CF ２ = CF - CF ２ -O-C ４ F ９ Preferably, at least one selected from the group consisting of CF ２ = CF - CF ２ -O-C ２ F ５ CF ２ = CF - CF ２ -O-C ３ F ７ , and CF ２ = CF - CF ２ -O-C ４ F ９ More preferably, at least one selected from the group consisting of CF ２ = CF - CF ２ -O-CF ２ CF ２ CF ３ That is even more preferable.

[0229] The above fluorinated vinyl heterocyclic material is general formula (230): (In the formula, X ２３１ and X ２３２ These are independently F, Cl, a methoxy group, or a fluorinated methoxy group, and Y ２３１ is formula Y ２３２ or formula Y ２３３ That is the case.

[0230] (In the formula, Z ２３１ and Z ２３２ Examples include fluorinated vinyl heterocyclic compounds represented by ), where is independently F or a fluorinated alkyl group having 1 to 3 carbon atoms.

[0231] As monomers that provide crosslinking sites, CF ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２ CN, CF ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２ COOH, CF ２ = CFOCF２ CF (CF ３ ) OCF ２ CF ２ CH ２ I, CF ２ = CFOCF ２ CF ２ CH ２ I, CH ２ = CFCF ２ OCF (CF ３ ) CF ２ OCF (CF ３ ) CN, CH ２ = CFCF ２ OCF (CF ３ ) CF ２ OCF (CF ３ ) COOH, CH ２ = CFCF ２ OCF (CF ３ ) CF ２ OCF (CF ３ )CH ２ OH, CH ２ =CHCF ２ CF ２ I, CH ２ =CH(CF ２ ) ２ CH=CH ２ ,CH ２ =CH(CF ２ ) ６ CH=CH ２ , and CF ２ = CFO (CF ２ ) ５ Preferably, it is at least one selected from the group consisting of CN, and CF ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２ CN and CF ２ = CFOCF ２ CF ２ CH ２ It is more preferable that it be at least one selected from the group consisting of I.

[0232] In the polymerization described above, the fluoromonomer may be polymerized with a fluorine-free monomer. Examples of the fluorine-free monomer include hydrocarbon monomers that are reactive with the fluoromonomer.

[0233] Examples of the hydrocarbon monomers mentioned above include alkenes such as ethylene, propylene, butylene, and isobutylene; alkyl vinyl ethers such as ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, isobutyl vinyl ether, and cyclohexyl vinyl ether; vinyl acetate, vinyl propionate, n-butyrate, vinyl isobutyrate, vinyl valerate, vinyl pivalate, vinyl caproate, vinyl caprylate, vinyl caprate, vinyl versatate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, vinyl benzoate, p-t-butylbenzoate, vinyl cyclohexanecarboxylate, vinyl monochloroacetate, vinyl adipate, vinyl acrylate, vinyl methacrylate, vinyl crotate, vinyl sorbate, vinyl cinnamate, vinyl undecylenate, vinyl hydroxyacetate, and hydroxyvinyl acetate. Examples include vinyl esters such as vinyl oxypropioate, vinyl hydroxybutyrate, vinyl hydroxyvalerate, vinyl hydroxyisobutyrate, and vinyl hydroxycyclohexanecarboxylate; alkyl allyl ethers such as ethyl allyl ether, propyl allyl ether, butyl allyl ether, isobutyl allyl ether, and cyclohexyl allyl ether; alkyl allyl esters such as ethyl allyl ester, propyl allyl ester, butyl allyl ester, isobutyl allyl ester, and cyclohexyl allyl ester; and (meth)acrylic acid esters such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, and vinyl methacrylate.

[0234] The above fluorine-free monomers may also be functional group-containing hydrocarbon monomers (excluding monomers that provide crosslinking sites). Examples of the above functional group-containing hydrocarbon monomers include hydroxyalkyl vinyl ethers such as hydroxyethyl vinyl ether, hydroxypropyl vinyl ether, hydroxybutyl vinyl ether, hydroxyisobutyl vinyl ether, and hydroxycyclohexyl vinyl ether; fluorine-free monomers having carboxyl groups such as acrylic acid, methacrylic acid, itaconic acid, succinic acid, succinic anhydride, fumaric acid, fumaric anhydride, crotonic acid, maleic acid, maleic anhydride, and perfluorobutenoic acid; fluorine-free monomers having sulfo groups such as vinyl sulfonic acid; fluorine-free monomers having glycidyl groups such as glycidyl vinyl ether and glycidyl allyl ether; fluorine-free monomers having amino groups such as aminoalkyl vinyl ether and aminoalkyl allyl ether; fluorine-free monomers having amide groups such as (meth)acrylamide and methylolacrylamide; and fluorine-free monomers having nitrile groups such as acrylonitrile and methacrylonitrile.

[0235] In the manufacturing method of the present disclosure, it is preferable to use at least TFE as the fluoromonomer. In one embodiment, TFE, or a combination of TFE and a fluoromonomer other than TFE, is used as the fluoromonomer. In one embodiment of the manufacturing method of the present disclosure, VDF is not used in polymerization.

[0236] In the polymerization described above, a desired fluororesin can be obtained by polymerizing one or more of the above-mentioned fluoromonomers.

[0237] (Fluororesin) By the above polymerization, an aqueous dispersion containing fluororesin can be obtained. By coagulating the fluororesin in the aqueous dispersion and drying it, fluororesin powder can be obtained. Alternatively, the coagulated material may be washed before drying.

[0238] In the manufacturing method of the present disclosure, for example, (I) tetrafluoroethylene polymer [TFE polymer (PTFE)] can be suitably produced as a non-melt-processable fluororesin, and (II) ethylene / TFE copolymer [ETFE], TFE / HFP copolymer [FEP], TFE / perfluoro(alkyl vinyl ether) copolymer [PFA, MFA, etc.], TFE / perfluoroallyl ether copolymer, TFE / VDF copolymer, and electrolyte polymer precursors can be suitably produced as melt-processable fluororesins.

[0239] The fluorine substitution rate of the fluororesin, calculated by the following formula, is preferably 50% or more, more preferably 55% or more, even more preferably 60% or more, even more preferably 75% or more, and particularly preferably 80% or more. Among the fluororesins, a fluororesin with a fluorine substitution rate of 90 to 100%, i.e., a perfluororesin, is the most preferred.

[0240] (Formula) Fluorine substitution rate (%) = (Number of fluorine atoms bonded to carbon atoms constituting the fluororesin) / ((Number of hydrogen atoms bonded to carbon atoms constituting the fluororesin) + (Number of fluorine and chlorine atoms bonded to carbon atoms constituting the fluororesin)) × 100

[0241] As the perfluororesin mentioned above, a fluororesin with a fluorine substitution rate of 95 to 100% is more preferred, PTFE, FEP, or PFA are even more preferred, and PTFE is even more preferred.

[0242] The above-mentioned fluororesin may have a core-shell structure. Examples of fluororesins having a core-shell structure include modified PTFE, which contains a core of high molecular weight PTFE and a shell of lower molecular weight PTFE or modified PTFE in the particles. Examples of such modified PTFE include the PTFE described in Japanese Patent Publication No. 2005-527652.

[0243] The above core-shell structure can take the following forms: Core: TFE homopolymer Shell: TFE homopolymer Core: Modified PTFE Shell: TFE homopolymer Core: Modified PTFE Shell: Modified PTFE Core: TFE homopolymer Shell: Modified PTFE Core: Low molecular weight PTFE Shell: High molecular weight PTFE Core: High molecular weight PTFE Shell: Low molecular weight PTFE

[0244] In the fluororesin having the above-described core-shell structure, the lower limit of the core ratio is preferably 0.5% by mass, more preferably 1.0% by mass, even more preferably 2.0% by mass, even more preferably 3.0% by mass, particularly preferably 5.0% by mass, and most preferably 10.0% by mass. The upper limit of the core ratio is preferably 99.5% by mass, more preferably 99.0% by mass, even more preferably 98.0% by mass, even more preferably 97.0% by mass, particularly preferably 95.0% by mass, and most preferably 90.0% by mass.

[0245] In the fluororesin having the above-described core-shell structure, the lower limit of the shell ratio is preferably 0.5% by mass, more preferably 1.0% by mass, even more preferably 2.0% by mass, even more preferably 3.0% by mass, particularly preferably 5.0% by mass, and most preferably 10.0% by mass. The upper limit of the shell ratio is preferably 99.5% by mass, more preferably 99.0% by mass, even more preferably 98.0% by mass, even more preferably 97.0% by mass, particularly preferably 95.0% by mass, and most preferably 90.0% by mass.

[0246] PTFE can be produced by polymerizing at least TFE as a fluoromonomer. Various known modified monomers can also be used in combination in the production of PTFE. In this disclosure, PTFE is a concept that includes not only TFE homopolymers but also copolymers of TFE and modified monomers (hereinafter referred to as "modified PTFE").

[0247] The above-mentioned modified monomers are not particularly limited as long as they can copolymerize with TFE, and include fluoromonomers and non-fluoromonomers. Furthermore, one or more modified monomers may be used.

[0248] The non-fluoro monomer is not particularly limited, and the general formula is CH ２ =CR Ｑ１ -LR Ｑ２ (In the formula, R Ｑ１ represents a hydrogen atom or alkyl group. L represents a single bond, -CO-O-*, -O-CO-*, or -O-. * is R Ｑ２ Represents the connection position with R. Ｑ２ Examples of monomers represented by ) are: (where represents a hydrogen atom, an alkyl group, or a nitrile group.)

[0249] Examples of nonfluoro monomers include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, vinyl methacrylate, vinyl acetate, acrylic acid, methacrylic acid, acrylonitrile, methacrylonitrile, ethyl vinyl ether, and cyclohexyl vinyl ether. Among these, butyl methacrylate, vinyl acetate, and acrylic acid are preferred as nonfluoro monomers.

[0250] Examples of fluoromonomers include perfluoroolefins such as hexafluoropropylene [HFP]; hydrogen-containing fluoroolefins such as trifluoroethylene and vinylidene fluoride [VDF]; perhaloolefins such as chlorotrifluoroethylene; perfluorovinyl ethers; (perfluoroalkyl)ethylenes; and perfluoroallyl ethers.

[0251] From the viewpoint of reactivity with TFE, the above modified monomer preferably contains at least one selected from the group consisting of hexafluoropropylene, perfluoro(alkyl vinyl ether), and (perfluoroalkyl)ethylene. More preferably, it contains at least one selected from the group consisting of hexafluoropropylene, perfluoro(methyl vinyl ether), perfluoro(propyl vinyl ether), (perfluorobutyl)ethylene, (perfluorohexyl)ethylene, and (perfluorooctyl)ethylene.

[0252] Once the polymerization of TFE is complete, an aqueous dispersion containing the TFE polymer (PTFE) can be obtained.

[0253] Fine powder can be produced by coagulating an aqueous dispersion of TFE polymer. The aqueous dispersion of TFE polymer can be used as a molding material for various applications (wire coatings, tubes, stretched films, etc.) as a fine powder after coagulation, washing, and drying. When coagulating the aqueous dispersion of TFE polymer, the aqueous dispersion obtained by polymerization of polymer latex, etc., is usually diluted with water to a polymer concentration of 5 to 20% by mass, and if necessary, the pH is adjusted to neutral or alkaline, and then the mixture is stirred more vigorously than during the reaction in a container equipped with a stirrer. The above coagulation may also be carried out while stirring with the addition of water-soluble organic compounds such as methanol and acetone, inorganic salts such as potassium nitrate and ammonium carbonate, or inorganic acids such as hydrochloric acid, sulfuric acid, and nitric acid as coagulants. The above coagulation may also be carried out continuously using an in-line mixer or the like.

[0254] The manufacturing method disclosed herein can also be used to produce low molecular weight PTFE.

[0255] Low molecular weight PTFE (also called PTFE micropowder) with a molecular weight of 600,000 or less has excellent chemical stability, extremely low surface energy, and is less prone to fibrillation. Therefore, it is suitable as an additive for the manufacture of plastics, inks, cosmetics, paints, greases, office automation equipment components, toners, etc., for purposes such as improving slipperiness and the texture of the coating surface (see, for example, Japanese Patent Publication No. 10-147617).

[0256] When using the low molecular weight PTFE obtained by the above polymerization as a powder, the above aqueous dispersion can be coagulated to form powder particles.

[0257] The manufacturing method of this disclosure can also produce high molecular weight PTFE as PTFE. In this disclosure, high molecular weight PTFE means PTFE that is non-melt processable. In one embodiment, high molecular weight PTFE has non-melt processability and fibrillation properties. On the other hand, low molecular weight PTFE means PTFE that is melt processable. In one embodiment, low molecular weight PTFE has melt processability and does not have fibrillation properties.

[0258] The above-mentioned non-melt processability refers to the property that the melt flow rate cannot be measured at a temperature higher than the crystallization melting point, in accordance with ASTM D 1238 and D 2116.

[0259] The presence or absence of fibrillation properties can be determined by "paste extrusion," a typical method for molding "high molecular weight PTFE powder," which is a powder made from a polymer of TFE. Paste extrusion is usually possible because high molecular weight PTFE has fibrillation properties. If the unfired molded product obtained by paste extrusion has no substantial strength or elongation, for example, if it has 0% elongation and breaks when pulled, it can be considered that it does not have fibrillation properties.

[0260] The above high molecular weight PTFE preferably has a standard specific gravity (SSG) of 2.130 to 2.280. The above standard specific gravity is measured using a sample molded in accordance with ASTM D4895-89 and measured by the water displacement method in accordance with ASTM D 792. In this disclosure, "high molecular weight" means that the above standard specific gravity is within the above range.

[0261] The above low molecular weight PTFE has a melt viscosity of 1 × 10⁻⁶ at 380°C. ２ ~7 x 10 ５ The molecular weight is Pa·s. In this disclosure, "low molecular weight" means that the melt viscosity is within the above range. The melt viscosity is measured in accordance with ASTM D 1238, using a flow tester (manufactured by Shimadzu Corporation) and a 2φ-8L die, by preheating a 2g sample at 380°C for 5 minutes and maintaining it at the above temperature under a load of 0.7 MPa.

[0262] The high molecular weight PTFE described above has an extremely high melt viscosity compared to the low molecular weight PTFE described above, making it difficult to accurately measure its melt viscosity. On the other hand, while the melt viscosity of the low molecular weight PTFE can be measured, it is difficult to obtain molded articles from the low molecular weight PTFE that can be used to measure standard specific gravity, making it difficult to accurately measure its standard specific gravity. Therefore, in this disclosure, standard specific gravity is used as an indicator of the molecular weight of the high molecular weight PTFE, and melt viscosity is used as an indicator of the molecular weight of the low molecular weight PTFE. It should be noted that no measurement method is known that can directly determine the molecular weight of either the high molecular weight PTFE or the low molecular weight PTFE.

[0263] The high molecular weight PTFE described above preferably has a peak temperature of 333 to 347°C, and more preferably 335 to 345°C. The low molecular weight PTFE described above preferably has a peak temperature of 322 to 333°C, and more preferably 324 to 332°C. The peak temperature can be determined by using a differential scanning calorimeter (DSC) to heat PTFE that has not been previously heated to a temperature of 300°C or higher at a rate of 10°C / min, and the temperature corresponding to the maximum value appearing in the heat of fusion curve obtained.

[0264] The peak temperature of PTFE may be between 322 and 347°C. When PTFE is high molecular weight PTFE, the upper limit of the peak temperature of PTFE may be 347°C or less, 346°C or less, 345°C or less, 344°C or less, 343°C or less, 342°C or less, 341°C or less, or 340°C or less. When PTFE is high molecular weight PTFE, the lower limit of the peak temperature of PTFE may be 333°C or higher or 335°C or higher. When PTFE is low molecular weight PTFE, the upper limit of the peak temperature of PTFE may be 333°C or lower or 332°C or lower. When PTFE is low molecular weight PTFE, the lower limit of the peak temperature of PTFE may be 322°C or higher or 324°C or higher.

[0265] The average primary particle diameter of the low molecular weight PTFE primary particles is preferably 10 to 350 nm, more preferably 100 nm or more, even more preferably 150 nm or more, even more preferably 400 nm or less, and even more preferably 350 nm or less.

[0266] The above high molecular weight PTFE is preferably such that, when PTFE that has not been heated to a temperature of 300°C or higher is heated at a rate of 10°C / min using a differential scanning calorimeter (DSC), at least one endothermic peak appears in the range of 333 to 347°C in the heat of fusion curve, and the heat of fusion amount at 290 to 350°C calculated from the above heat of fusion curve is 52 mJ / mg or more. The heat of fusion amount of the PTFE is more preferably 55 mJ / mg or more, and even more preferably 58 mJ / mg or more.

[0267] The manufacturing method of the present disclosure can also be used to produce TFE / HFP copolymer (FEP). The preferred monomer composition (mass%) of FEP is TFE:HFP = (60-95):(5-40), more preferably (85-92):(8-15).

[0268] In addition to TFE and HFP, a copolymer of TFE, HFP, and other monomers may be obtained as FEP by polymerizing other monomers copolymerizable with these monomers. Examples of other monomers include the fluorine-containing monomers (excluding TFE and HFP) and fluorine-free monomers mentioned above. One or more types of other monomers can be used. Perfluoro(alkyl vinyl ether) is preferred as the other monomer. The content of other monomer units in FEP may be 0.1 to 2% by mass relative to the total monomer units.

[0269] TFE / perfluoro(alkyl vinyl ether) copolymer (PFA) can also be produced by the manufacturing method disclosed herein. The preferred monomer composition (mol%) of the TFE / perfluoro(alkyl vinyl ether) copolymer is TFE:perfluoro(alkyl vinyl ether) = (90-99.7):(0.3-10), more preferably (97-99):(1-3). The perfluoro(alkyl vinyl ether) is of the formula: CF ２ = CFORF ４ (wherein, Rf ４ It is preferable to use a perfluoroalkyl group having 1 to 6 carbon atoms.

[0270] In addition to TFE and perfluoro(alkyl vinyl ether), a copolymer of TFE, perfluoro(alkyl vinyl ether), and other monomers copolymerized with these monomers may be obtained as a TFE / perfluoro(alkyl vinyl ether) copolymer. Examples of other monomers include the fluorine-containing monomers (excluding TFE and perfluoro(alkyl vinyl ether)) and fluorine-free monomers mentioned above. One or more types of other monomers can be used. The content of other monomer units in the TFE / perfluoro(alkyl vinyl ether) copolymer may be 0.1 to 2% by mass relative to the total monomer units.

[0271] 2. Fluoropolymers Furthermore, this disclosure substantially does not contain fluorine-containing surfactants, has an average primary particle size of 500 nm or less, and the color tone L* value of a test specimen made from fluoropolymer in accordance with ASTM D4895-89 is greater than 60, and the carboxylic acid / CF measured by infrared spectroscopy is ２ This also applies to fluororesins whose peak intensity ratio is 0.0050 or higher.

[0272] Furthermore, this disclosure relates to low molecular weight polytetrafluoroethylene (low molecular weight PTFE) which substantially does not contain fluorine-containing surfactants, has an average primary particle diameter of 500 nm or less, and has a color tone L* value greater than 60 after the grease prepared by mixing it with lubricating oil is held at 200°C for 30 hours.

[0273] Fluororesins are characterized by a color tone L* value greater than 60 in a test specimen prepared from the fluororesin, in accordance with ASTM D4895-89. The color tone L* value of a test specimen prepared from the fluororesin can be measured by a measurement method in accordance with JIS Z 8781-4:2013. The color tone L* value may be 65 or higher, 70 or higher, 75 or higher, 80 or higher, or 85 or higher.

[0274] Low molecular weight PTFE is characterized by a color tone L* value greater than 60 after the grease prepared by mixing it with lubricating oil is held at 200°C for 30 hours. The color tone L* value of grease prepared from low molecular weight PTFE can be measured according to JIS Z 8781-4:2013. An example of a lubricating oil used in the preparation of the grease is Demnam S-200 (manufactured by Daikin Industries, Ltd.). The color tone L* value may be 65 or higher, 70 or higher, 75 or higher, or 80 or higher.

[0275] The average primary particle diameter of the fluororesin and low molecular weight PTFE is 500 nm or less, preferably 450 nm or less, more preferably 400 nm or less, even more preferably 350 nm or less, even more preferably 300 nm or less, particularly preferably 250 nm or less, preferably 10 nm or more, more preferably 100 nm or more, and even more preferably 150 nm or more.

[0276] By producing fluororesin and low molecular weight PTFE using the manufacturing method disclosed herein, the average primary particle size of the fluororesin and low molecular weight PTFE can be adjusted to within the above-mentioned range. This is presumed to be because the polymerization reaction proceeds with the fluororesin emulsified in an aqueous medium. On the other hand, when fluororesin is produced by conventional suspension polymerization methods, it is difficult to generate primary particles of the fluororesin, and a fluororesin having an average primary particle size within the above-mentioned range cannot be obtained.

[0277] The average primary particle diameter is the average particle diameter of primary particles dispersed in an aqueous dispersion, and is different from the average particle diameter of secondary particles (powder) formed by the aggregation of primary particles. The average primary particle diameter can be measured by dynamic light scattering. First, an aqueous dispersion is prepared with a polymer solid content concentration of approximately 1.0 mass%, and then measured using dynamic light scattering with a measurement temperature of 25°C, a refractive index of 1.3328 for the solvent (water), a viscosity of 0.8878 mPa·s for the solvent (water), and 70 cumulative measurements. For example, the ELSZ-1000S (manufactured by Otsuka Electronics Co., Ltd.) can be used for dynamic light scattering.

[0278] Furthermore, the average primary particle diameter can also be measured by the following method: Dilute the dispersion with water until the solid content concentration reaches 0.15% by mass. Measure the transmittance of 550 nm projection light per unit length of the resulting diluted latex, and the average particle diameter determined by measuring the directional diameter using a transmission electron microscope image, to create a calibration curve. Using this calibration curve, the average particle diameter can be determined from the measured transmittance of 550 nm projection light for each sample.

[0279] In one embodiment, carboxylic acid / CF of fluororesin ２ The peak intensity ratio is 0.0050 or higher. In another embodiment, the fluororesin is low molecular weight PTFE, and the carboxylic acid / CF of the low molecular weight PTFE ２ The peak intensity ratio is 0.0050 or higher. Carboxylic acid / CF ２ The peak intensity ratio can be measured by infrared spectroscopy of fluororesins.

[0280] In addition to having the above-described configuration, the low molecular weight PTFE obtained by the manufacturing method of the present disclosure may also have the above-described configuration.

[0281] In addition to having the above-described configuration, the fluororesin of this disclosure may also have the above-described configuration as a configuration obtained by the manufacturing method of this disclosure. Furthermore, the fluororesin of this disclosure may have the following characteristic configurations.

[0282] In one embodiment, the standard specific gravity of the fluororesin of this disclosure is 2.230 or less. The standard specific gravity of the fluororesin can be measured by the method described in the examples below.

[0283] In one embodiment, the tensile strength of the fluororesin of this disclosure is 15.0 N or higher. The tensile strength of the fluororesin can be measured by the method described in the examples later. A fluororesin that cannot produce a stretched bead and whose tensile strength cannot be measured by the method described in the examples later means that it does not have a tensile strength of 15.0 N or higher. The tensile strength of the fluororesin can be increased, for example, by appropriately selecting the type and amount of chain transfer agent in the manufacturing method of this disclosure. For example, using a moderate amount of a chain transfer agent with an appropriate chain transfer constant makes it easier to adjust the tensile strength of the fluororesin to within the above range.

[0284] In one embodiment, the thermal decomposition rate of the fluororesin of this disclosure at high temperatures is 0.030% or more. The thermal decomposition rate of the fluororesin at high temperatures can be measured by the method described in the examples below.

[0285] In one embodiment, the yellow index value of the fluororesin of this disclosure is -20 to 20. The yellow index value of the fluororesin can be measured by the method described in the examples below.

[0286] The fluororesins and low molecular weight PTFE of this disclosure can be suitably produced by the manufacturing methods of this disclosure.

[0287] This disclosure also relates to compositions containing the fluororesin of this disclosure or the low molecular weight PTFE of this disclosure. The form of the fluororesin of this disclosure, the low molecular weight PTFE of this disclosure and the compositions of this disclosure is not particularly limited, but may be, for example, an aqueous dispersion, a coagulation, a dry product, a powder, a pellet, etc. An aqueous dispersion is a dispersion system in which an aqueous medium is the dispersion medium and the fluororesin or low molecular weight PTFE is the dispersed phase. The aqueous medium is not particularly limited as long as it is a liquid containing water, and may contain, for example, an organic solvent such as alcohol, ether, ketone, or paraffin wax in addition to water.

[0288] The fluororesins, low molecular weight PTFEs, and compositions of this disclosure may be aqueous dispersions in which primary particles of fluororesins or low molecular weight PTFE are dispersed in an aqueous medium. The aqueous dispersion may be an aqueous dispersion obtained by the polymerization described above, a dispersion obtained by concentrating or stabilizing this aqueous dispersion, or a dispersion of fluororesin powder in an aqueous medium. Furthermore, the fluororesins, low molecular weight PTFEs, and compositions of this disclosure may be fluororesin powder or low molecular weight PTFE powder. Fluororesin powder or low molecular weight PTFE powder can be obtained, for example, by coagulating fluororesin or low molecular weight PTFE in an aqueous dispersion using a known method.

[0289] The fluororesins of this disclosure, the low molecular weight PTFE of this disclosure, and the fluororesins and low molecular weight PTFE in the compositions of this disclosure may have the same composition as the fluororesins and low molecular weight PTFE obtained by the manufacturing methods of this disclosure. Therefore, examples of fluororesins include tetrafluoroethylene polymers [TFE polymers (PTFE)] and melt-processable fluororesins.

[0290] The fluororesin may be a polymer that is non-melt processable or a polymer that is melt processable. A non-melt processable fluororesin or a melt processable fluororesin is preferred as the fluororesin.

[0291] The fluorine substitution rate of the fluororesin is preferably 50% or more, more preferably 55% or more, even more preferably 60% or more, still more preferably 75% or more, and particularly preferably 80% or more. The fluorine substitution rate of the fluororesin is most preferably 90 to 100%.

[0292] As the above-mentioned fluororesin, fluororesins are preferred, and among them, fluororesins with a fluorine substitution rate of 50% or more calculated by the following formula are more preferred, fluororesins with a fluorine substitution rate exceeding 50% are even more preferred, fluororesins with a fluorine substitution rate of 55% or more are even more preferred, fluororesins with a fluorine substitution rate of 60% or more are even more preferred, fluororesins with a fluorine substitution rate of 75% or more are even more preferred, fluororesins with a fluorine substitution rate of 80% or more are particularly preferred, and fluororesins with a fluorine substitution rate of 90 to 100%, i.e., perfluororesins, are most preferred.

[0293] (Formula) Fluorine substitution rate (%) = (Number of fluorine atoms bonded to carbon atoms constituting the fluororesin) / ((Number of hydrogen atoms bonded to carbon atoms constituting the fluororesin) + (Number of fluorine and chlorine atoms bonded to carbon atoms constituting the fluororesin)) × 100

[0294] As the perfluororesin mentioned above, a fluororesin with a fluorine substitution rate of 95 to 100% is more preferred, PTFE, FEP, or PFA are even more preferred, and PTFE is even more preferred. In one embodiment of the fluororesin, the fluororesin does not contain VDF units.

[0295] One embodiment of the fluororesin, low molecular weight PTFE, and composition of the Disclosure is substantially free of surfactants. The fluororesin, low molecular weight PTFE, and composition that are substantially free of surfactants have the advantage of being less prone to discoloration.

[0296] In this disclosure, "substantially free of surfactants" means that the surfactant content in the fluororesin, low molecular weight PTFE, or composition is 10 ppm by mass or less, preferably 1 ppm by mass or less, more preferably 100 ppb by mass or less, even more preferably 10 ppb by mass or less, even more preferably 1 ppb by mass or less, and particularly preferably the surfactant is below the detection limit as measured by liquid chromatography-mass spectrometry (LC / MS).

[0297] In one embodiment of the fluororesin, low molecular weight PTFE, and composition of the Disclosure, a fluorine-free surfactant is substantially absent. The fluororesin, low molecular weight PTFE, and composition that are substantially absent from the fluorine-free surfactant have the advantage of being less prone to discoloration.

[0298] In this disclosure, "substantially free of fluorine-free surfactants" means that the content of fluorine-free surfactants in the fluororesin, low molecular weight PTFE, or composition is 10 ppm by mass or less, preferably 1 ppm by mass or less, more preferably 100 ppb by mass or less, even more preferably 10 ppb by mass or less, and particularly preferably the fluorine-free surfactant content is below the detection limit as measured by liquid chromatography-mass spectrometry (LC / MS).

[0299] One embodiment of the fluororesin, low molecular weight PTFE, and composition of the present disclosure substantially does not contain a fluorine-containing surfactant.

[0300] In this disclosure, "substantially free of fluorine-containing surfactants" means that the content of fluorine-containing surfactants in the fluororesin, low molecular weight PTFE, or composition is 10 ppm by mass or less, preferably 1 ppm by mass or less, more preferably 100 ppb by mass or less, even more preferably 1 ppb by mass or less, and particularly preferably the fluorine-containing surfactant is below the detection limit as measured by liquid chromatography-mass spectrometry (LC / MS).

[0301] The content of surfactants, such as fluorine-containing surfactants, can be quantified by known methods. For example, it can be quantified by LC / MS analysis. First, methanol is added to the fluororesin, low molecular weight PTFE, or composition, and extraction is performed. The obtained extract is then analyzed by LC / MS. To further improve the extraction efficiency, treatment by Soxhlet extraction, sonication, etc., may be performed. Molecular weight information is extracted from the obtained LC / MS spectrum, and its agreement with the structural formula of the candidate surfactant is confirmed. Subsequently, aqueous solutions with five or more levels of the confirmed surfactant content are prepared, and LC / MS analysis is performed on each aqueous solution. The relationship between the content and the area area corresponding to that content is plotted, and a calibration curve is drawn. Then, using the calibration curve, the area area of ​​the LC / MS chromatogram of the surfactant in the extract can be converted to the surfactant content.

[0302] Examples of the fluorine-containing surfactant include compounds represented by the following formula. The fluorine-containing surfactant may be a mixture of these compounds. F(CF) ２ ) ５ COOM, CF ３ O(CF) ２ ) ３ OCHFCF ２ COOM, C ３ F ７ OCF (CF ３ ) CF ２ OCF (CF ３ ) COOM, CF ３ CF ２ CF ２ OCF (CF ３ ) COOM, CF ３ CF ２ OCF ２ CF ２ OCF ２ COOM, C ２ F ５ OCF (CF ３ ) CF ２ OCF (CF ３ ) COOM, CF ３ OCF (CF ３ ) CF ２ OCF (CF ３) COOM, CF ２ ClCF ２ CF ２ OCF (CF ３ ) CF ２ OCF ２ COOM, CF ２ ClCF ２ CF ２ OCF ２ CF (CF ３ ) OCF ２ COOM, CF ２ ClCF(CF ３ )OCF(CF ３ ) CF ２ OCF ２ COOM, CF ２ ClCF(CF ３ ) OCF ２ CF (CF ３ ) OCF ２ COOM, and, (In each formula, M is H, metal atom, NR １ ４ , optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium. １ (This is either H or an organic group.)

[0303] In one embodiment of the fluororesins, low molecular weight PTFEs, and compositions of the Disclosure, a polymer (I) containing polymerization units (I) based on a monomer (I) represented by general formula (I) is substantially absent. Fluororesins, low molecular weight PTFEs, and compositions substantially absent from polymer (I) have the advantage of being less prone to discoloration. General formula (I): CX １ X ３ = CX ２ R(-CZ) １ Z ２ -A ０ ) ｍ (In the formula, X １ and X ３ These are F, Cl, H, or CF, each independently. ３ X ２ is H, F, alkyl group or fluorine-containing alkyl group; A ０ is an anionic group; R is a linking group; Z １and Z ２ Each of these is independently H, F, an alkyl group, or a fluorinated alkyl group; m is an integer of 1 or more.

[0304] In this disclosure, "substantially free of polymer (I)" means that the content of polymer (I) in the fluororesin, low molecular weight PTFE, or composition is 10 ppm by mass or less, preferably 1 ppm by mass or less, more preferably 100 ppb by mass or less, even more preferably 10 ppb by mass or less, and particularly preferably polymer (I) is below the detection limit as measured by liquid chromatography-mass spectrometry (LC / MS).

[0305] The content of polymer (I) in fluororesin, low molecular weight PTFE, or composition can be determined by solid-state NMR measurement or melt-state NMR measurement. If polymer (I) contains carbonyl groups, it can also be determined by Fourier transform infrared spectroscopy. Also, see International Publication No. 2014 / 099453, International Publication No. 2010 / 075497, International Publication No. 2010 / 075496, International Publication No. 2011 / 008381, International Publication No. 2009 / 055521, International Publication No. 1987 / 007619, Japanese Patent Publication No. 61-293476, International Publication No. 2010 / 075494, International Publication No. 2010 / 075359, International Publication No. 2012 / 082454, International Publication No. 2006 / 119224, International Publication No. 2013 / 085864, and International Publication No. 2012 / 082707, International Publication No. 2012 / 082703, International Publication No. 2012 / 082451, International Publication No. 2006 / 135825, International Publication No. 2004 / 067588, International Publication No. 2009 / 068528, Japanese Patent Publication No. 2004-075978, Japanese Patent Publication No. 2001-226436, International Publication No. 1992 / 017635, International Publication No. 2014 / 069165, Japanese Patent Publication No. 11-181009, etc., describe the measurement methods for each polymer. The measurement methods for each polymer described in these publications can be used as the method for measuring the content of polymer (I).

[0306] The fluororesins, low molecular weight PTFE, and compositions of the present disclosure can be suitably used for the applications described above.

[0307] Although embodiments have been described above, it should be understood that various modifications to the form and details are possible without departing from the spirit and scope of the claims.

[0308] <1> According to the first aspect of this disclosure, a method for producing an aqueous dispersion of a fluororesin is provided, comprising: (1) preparing an aqueous solution containing a water-soluble fluoropolymer by performing a first polymerization of a fluoromonomer in the presence of an aqueous medium and a polymerization initiator, substantially in the absence of a fluorine-containing surfactant; and (2) preparing an aqueous dispersion containing a fluororesin by performing a second polymerization of a fluoromonomer in the presence of the aqueous solution, substantially in the absence of a fluorine-containing surfactant, wherein the content of the water-soluble fluoropolymer in the aqueous solution is greater than 0% by mass and less than 1.0% by mass with respect to the mass of the aqueous solution; the content of the fluororesin in the aqueous dispersion is 15% by mass or more with respect to the mass of the aqueous dispersion; the polymerization rate of the first polymerization is 3.0 g / (hr·L) or less; and the second polymerization is performed substantially in the absence of a fluorine-free anionic surfactant from the start of the second polymerization until the content of the fluororesin in the aqueous dispersion reaches 10% by mass with respect to the mass of the aqueous dispersion. <2> According to a second aspect of the present disclosure, a method for producing a product according to the first aspect is provided, wherein the fluoromonomer in the first polymerization comprises at least tetrafluoroethylene. <3> According to a third aspect of the present disclosure, a method for producing a product according to the first or second aspect is provided, wherein the melting point of the water-soluble fluoropolymer is 250 to 330°C, or the glass transition temperature of the water-soluble fluoropolymer is 10°C or less. <4> According to a fourth aspect of the present disclosure, a method for producing a product according to any of the first to third aspects is provided, wherein a polymerization initiator is added in the second polymerization.<5> According to the fifth aspect of this disclosure, a method for producing an aqueous dispersion of a fluororesin is provided, comprising: (1) preparing an aqueous solution containing a water-soluble fluoropolymer by performing a first polymerization of a fluoromonomer in the presence of an aqueous medium and a polymerization initiator, substantially in the absence of a fluorine-containing surfactant; and (2) preparing an aqueous dispersion containing a fluororesin by performing a second polymerization of a fluoromonomer in the presence of the aqueous solution, substantially in the absence of a fluorine-containing surfactant, wherein the content of the water-soluble fluoropolymer in the aqueous solution is greater than 0% by mass and less than 1.0% by mass with respect to the mass of the aqueous solution; the content of the fluororesin in the aqueous dispersion is 15% by mass or more with respect to the mass of the aqueous dispersion; and the ratio of radical generation (B / A) calculated by the following formula is 0.7 or less. Ratio of radical generation (B / A) = B / A A: Amount of radicals generated per gram of aqueous medium per minute from the time the polymerization initiator of the first polymerization is first added (A) (mol / (g・min)) B: Amount of radicals generated per gram of aqueous medium per minute from the start of the second polymerization (B) (mol / (g・min)) <6> According to the sixth aspect of this disclosure, a method for production according to the fifth aspect is provided, wherein the fluoromonomer comprises at least tetrafluoroethylene. <7> According to the seventh aspect of this disclosure, a method for production according to the fifth or sixth aspect is provided, wherein the polymerization rate of the first polymerization is 3.0 g / (hr・L) or less. <8> According to the eighth aspect of this disclosure, a method for production according to any of the fifth to seventh aspects is provided, wherein the melting point of the water-soluble fluoropolymer is 250 to 330°C, or the glass transition temperature of the water-soluble fluoropolymer is 10°C or less. <9> According to the ninth aspect of this disclosure, a manufacturing method according to any of the fifth to eighth aspects is provided, wherein a polymerization initiator is further added in the second polymerization.<10> According to the tenth aspect of this disclosure, (1) an aqueous solution containing a water-soluble fluoropolymer is prepared by performing a first polymerization of a fluoromonomer in the presence of an aqueous medium and a polymerization initiator, substantially in the absence of a fluorine-containing surfactant; and (2) an aqueous dispersion containing a fluororesin is prepared by performing a second polymerization of a fluoromonomer in the presence of the aqueous solution, substantially in the absence of a fluorine-containing surfactant, wherein the content of the water-soluble fluoropolymer in the aqueous solution is greater than 0% by mass and less than 1.0% by mass with respect to the mass of the aqueous solution; the content of the fluororesin in the aqueous dispersion is 15% by mass or more with respect to the mass of the aqueous dispersion; the polymerization initiator present in the first polymerization is a thermal decomposition type radical polymerization initiator, the first polymerization is started by adding the polymerization initiator, and the first polymerization continues until 90% by mass or more of the initially added polymerization initiator is decomposed; the melting point of the water-soluble fluoropolymer is 250 to 330°C, or the glass transition temperature of the water-soluble fluoropolymer is 10°C or less. A manufacturing method is provided in which the second polymerization is carried out substantially in the absence of a fluorine-free anionic surfactant from the start of the second polymerization until the content of the fluororesin in the aqueous dispersion reaches 10% by mass relative to the mass of the aqueous dispersion. <11> According to the 11th aspect of the present disclosure, a manufacturing method according to the 10th aspect is provided in which the fluoromonomer in the first polymerization contains at least tetrafluoroethylene. <12> According to the 12th aspect of the present disclosure, a manufacturing method according to the 10th or 11th aspect is provided in which the polymerization rate of the first polymerization is 3.0 g / (hr·L) or less. <13> According to the 13th aspect of the present disclosure, a manufacturing method according to any of the 10th to 12th aspects is provided in which a polymerization initiator is added in the second polymerization. <14> According to the fourteenth aspect of this disclosure, a fluororesin that substantially does not contain fluorine-containing surfactants, has an average primary particle diameter of 500 nm or less, has a color tone L* value greater than 60 of a test specimen prepared from the fluororesin in accordance with ASTM D4895-89, and has a carboxylic acid / CF measured by infrared spectroscopy. ２A fluororesin is provided in which the peak intensity ratio is 0.0050 or more. <15> According to the 15th aspect of the present disclosure, a fluororesin according to the 14th aspect in which the standard specific gravity is 2.230 or less is provided. <16> According to the 16th aspect of the present disclosure, a fluororesin according to the 14th or 15th aspect in which the tensile strength is 15.0 N or more is provided. <17> According to the 17th aspect of the present disclosure, a fluororesin according to any one of the 14th to 16th aspects in which the thermal decomposition rate at high temperature is 0.030% or more and the yellow index value is -20 to 20 is provided. <18> According to the 18th aspect of the present disclosure, a fluororesin according to any one of the 14th to 17th aspects in which the thermal decomposition rate at high temperature is 0.030% or more and the tensile strength is 15.0 N or more is provided. <19> According to the 19th aspect of the present disclosure, a fluororesin according to any one of the 14th to 18th aspects that substantially does not contain a fluorine-free surfactant is provided. <20> According to the 20th aspect of the present disclosure, a fluororesin according to any one of the 14th to 19th aspects that substantially does not contain a polymer (I) including a polymerization unit (I) based on a monomer (I) represented by the general formula (I) is provided. General formula (I): CX １ X ３ =CX ２ R(−CZ １ Z ２ −A ０ )(In the formula, X ｍ and X １ and X ３ are each independently F, Cl, H or CF ３ ; X ２ is H, F, an alkyl group or a fluorine-containing alkyl group; A ０ is an anionic group; R is a linking group; Z １ and Z ２(Each is independently H, F, an alkyl group, or a fluorine-containing alkyl group; m is an integer of 1 or more.) <21> According to the 21st aspect of this disclosure, a low molecular weight polytetrafluoroethylene is provided which is substantially free of fluorine-containing surfactants, has an average primary particle diameter of 500 nm or less, and has a color tone L* value greater than 60 after a grease prepared by mixing with a lubricating oil is held at 200°C for 30 hours. <22> According to the 22nd aspect of this disclosure, the carboxylic acid / CF measured by infrared spectroscopy is provided. ２ A low molecular weight polytetrafluoroethylene is provided, according to a 21st viewpoint, having a peak intensity ratio of 0.0050 or higher.

[0309] Next, embodiments of the present disclosure will be described with reference to examples, but the present disclosure is not limited to such embodiments.

[0310] Each value in the examples was measured by the following method.

[0311] <Solid content concentration in aqueous dispersion> 1 g of aqueous dispersion is dried in a forced-air dryer at 150°C for 60 minutes, and the value obtained by expressing the ratio of the mass of the residual material to the mass of the aqueous dispersion (1 g) as a percentage is adopted.

[0312] <Average Primary Particle Size> The aqueous dispersion was diluted with water until the solid content concentration was 0.15% by mass. A calibration curve was created by measuring the transmittance of 550 nm projected light per unit length of the resulting diluted latex and the average primary particle size determined by measuring the directional diameter using transmission electron microscopy. Using this calibration curve, the average primary particle size was determined from the measured transmittance of 550 nm projected light for each sample.

[0313] <Standard Specific Gravity (SSG)> Samples molded in accordance with ASTM D4895-89 were used, and the SSG was measured by the water displacement method in accordance with ASTM D-792.

[0314] <Melting Point (Peak Temperature) 1> For the water-soluble polymer obtained in the example, the temperature was raised in an aluminum pan in an atmospheric environment from 25°C to 600°C at a rate of 10°C / min using a differential thermogravimetric analyzer [TG / DTA], and the temperature corresponding to the maximum value of the differential thermal (DTA) curve was determined.

[0315] <Glass Transition Temperature> For the water-soluble polymers obtained in the examples, a differential scanning calorimeter (DSC) was used to plot the heat of fusion curve under a heating rate of 10°C / min. The temperature corresponding to the maximum value of the endothermic peak appearing in the heat of fusion curve was defined as the glass transition temperature of the water-soluble polymer.

[0316] <Melting Point (Peak Temperature) 2> For the PTFE powder obtained in the example, a differential scanning calorimeter (DSC) was used to draw a heat of fusion curve at a heating rate of 10°C / min, and the temperature corresponding to the maximum value of the endothermic peak appearing in the heat of fusion curve was defined as the melting point of PTFE.

[0317] <Thermal Decomposition Rate at High Temperatures> Approximately 10 g of PTFE powder was placed in an aluminum cup (capacity 50 ml, top diameter 61 mm, bottom diameter 42 mm, depth 33 mm). After holding it for 2 hours in a hot air circulating electric furnace preheated to the heating temperature at 370 ± 2 °C, the weight was measured, and the thermal decomposition rate at high temperatures was calculated using the following formula: Thermal decomposition rate at high temperatures (mass %) = (Weight of PTFE powder before heat treatment (g) - Weight of PTFE powder after heat treatment (g)) / Weight of PTFE powder before heat treatment (g) × 100

[0318] <Color Tone L* Value, Yellow Index Value> Test specimens were prepared from fluororesin in accordance with ASTM D4895-89. Using a color meter ZE6000 manufactured by Nippon Denshoku Industries, Ltd., the color tone L* was measured according to the measurement method in accordance with JIS Z 8781-4:2013, and the yellow index value was measured according to ASTME 313.

[0319] <Carboxylic acid / CF ２ Peak intensity ratio > Fluoropolymer powder was pre-formed by hand pressing to create a film with a thickness of approximately 0.1 mm. The prepared film was analyzed using infrared absorption spectroscopy, and the peak intensity of the carboxylic acid group (absorption frequency 3560) / CF ２ It was calculated based on the peak intensity (absorption frequency 1200).

[0320] <Measurement of Extrusion Pressure> Add 21.7 g of lubricant (product name: Isopar H (trademark registered), manufactured by Exxon) to 100 g of PTFE powder and mix in a glass bottle at room temperature for 3 minutes. Then, leave the glass bottle at room temperature (25°C) for at least 1 hour before extrusion to obtain lubricating resin. The lubricating resin is paste-extruded through an orifice (2.5 mm, land length 11 mm, introduction angle 30°) at a reduction ratio of 100:1 at room temperature to obtain a uniform bead (extruded molded body). The extrusion speed, i.e., the ram speed, is set to 20 inches / min (51 cm / min). The extrusion pressure is the value obtained by measuring the load when the extrusion load reaches equilibrium during paste extrusion and dividing it by the cross-sectional area of ​​the cylinder used for paste extrusion.

[0321] <Stretch Test> The lubricant is removed from the bead obtained by the paste extrusion described above by heating it at 230°C for 30 minutes. Next, the bead (extruded body) is cut to an appropriate length, and each end is fixed to a clamp so that the clamping distance is 1.5 inches (38 mm), and heated to 300°C in an air-circulating furnace. Then the clamps are separated at a desired speed (stretching speed) until a separation distance corresponding to the desired stretch (total stretch) is reached, and a stretch test is performed. This stretching method is essentially the same as the method disclosed in U.S. Patent No. 4,576,869, except that the extrusion speed is different (51 cm / min instead of 84 cm / min). 'Stretch' is the increase in length due to stretching, and is usually expressed in relation to the original length. In the above manufacturing method, the stretching speed is 1000% / second, and the total stretch is 2400%.

[0322] <Tensile Strength> The stretched bead obtained in the above stretch test (made by stretching the bead) is clamped and fixed in a movable jaw with a gauge length of 5.0 cm, and a tensile test is performed at a speed of 300 mm / min at 25°C, and the strength at which it breaks is measured as the tensile strength.

[0323] <Stress Relaxation Time> Connect both ends of the stretched bead obtained in the stretching test above to a fastener to create a taut bead sample with a total length of 8 inches (20 cm). Maintain the oven at 390°C and insert the fastener into the oven through a (covered) slit on the side of the oven. Measure the time required from the moment of insertion into the oven until the bead sample breaks as the stress relaxation time.

[0324] <Grease Color Tone L* Value> A grease was prepared by thoroughly mixing 30 parts by mass of low molecular weight PTFE and 70 parts by mass of Demnam S-200 (manufactured by Daikin Industries, Ltd.). The sample, held at 200°C for 30 hours, was measured using a color meter ZE6000 manufactured by Nippon Denshoku Industries, Ltd., based on the measurement method in accordance with JIS Z 8781-4:2013.

[0325] Example 1 A glass reactor with a stirrer and an internal volume of 1 L was charged with 27.5 g of paraffin, 0.00033 g of Pronon #104 (manufactured by NOF Corporation, average molecular weight 1670), a fluorine-free nonionic surfactant, and 520 g of deionized water as a nucleating agent, and then sealed. The reactor was then heated to 90°C while being suctioned and simultaneously purged with a TFE to remove oxygen from the reactor, and stirred at a speed of 540 rpm. 0.5 g of HFP was charged into the reactor and injected under pressure with a TFE until the pressure reached 0.78 MPaG. The reactor was kept at 90°C, the stirring speed was changed to 100 rpm, and then 0.11 g of ammonium persulfate (APS) dissolved in 10 g of deionized water was added, and the pressure inside the reactor was increased to 0.83 MPaG with a TFE.

[0326] Two hours after adding APS, the pressure inside the reactor was 0.75 MPaG. The reactor temperature was changed to 70°C, and the contents of the reactor were aspirated and simultaneously purged with TFE. The reactor temperature was maintained at 70°C, and 3 hours and 3 minutes after the initial addition of APS, the stirring speed was changed to 540 rpm, and at the same time, 0.0055 g of APS dissolved in 20 g of deionized water was added, and the pressure inside the reactor was increased to 0.83 MPaG with TFE. The total amount of water added to the reactor was 550 g. The solid content concentration of the water-soluble fluoropolymer obtained in the first polymerization was 0.33 mass%, and the melting point of the water-soluble fluoropolymer was 302.5°C. The polymerization rate of the first polymerization was 1.07 g / (hr·L). The radical generation ratio (B / A) at this time was 0.008.

[0327] A decrease in pressure was observed again, and thereafter TFE was added to the reactor to maintain a constant pressure of 0.78 MPaG. When the amount of TFE consumed in the reaction reached 125 g, the supply of TFE was stopped, stirring was halted, and the reaction was terminated. Subsequently, the reactor was evacuated until the pressure returned to atmospheric pressure, the contents were removed from the reactor and cooled, the separated paraffin was removed, and a PTFE aqueous dispersion was obtained. No polymer adhesion to the reactor was observed. The second polymerization was completed in 4 hours and 5 minutes, and the polymerization rate of the second polymerization was 55.7 g / (hr·L).

[0328] The obtained PTFE aqueous dispersion had a solid content concentration of 18.8% by mass and an average primary particle size of 210 nm. The obtained PTFE aqueous dispersion was diluted to a solid content concentration of 15% by mass using deionized water, and coagulation was performed by high-speed stirring to obtain a wet polymer. The obtained wet polymer was dried at 150°C for 18 hours to obtain PTFE powder.

[0329] The obtained PTFE powder had a standard specific gravity of 2.225 and a peak temperature of 336°C determined by DSC, indicating it was high molecular weight PTFE. Carboxylic acid / CF ２ The peak intensity ratio was 0.019, the thermal decomposition rate at high temperatures was 0.282%, the color L* value of the sample molded according to ASTM D4895-89 was 92.1, and the yellow index value was -6.1.

[0330] When the obtained PTFE powder was stretched, the extrusion pressure was 19.7 MPa and the stretch strength was 15.2 N.

[0331] Example 2 A glass reactor with a stirrer and an internal volume of 1 L was charged with 27.5 g of paraffin and 520 g of deionized water, and then sealed. The reactor was then heated to 90°C while being suctioned and simultaneously purged with a TFE to remove oxygen from the reactor, and stirred at a speed of 540 rpm. 0.17 g of propane was charged into the reactor as a chain transfer agent and injected under pressure with a TFE until the pressure reached 0.78 MPaG. The reactor was kept at 90°C, the stirring speed was changed to 100 rpm, and then 0.055 g of APS dissolved in 10 g of deionized water was added, and the pressure inside the reactor was increased to 0.83 MPaG with a TFE.

[0332] Two hours after adding APS, the pressure inside the reactor reached 0.78 MPaG. The reactor temperature was changed to 70°C, and the contents of the reactor were aspirated and simultaneously purged with TFE. The reactor temperature was maintained at 70°C, and 2 hours and 51 minutes after the initial addition of APS, the stirring speed was changed to 540 rpm, and at the same time, 0.0055 g of APS dissolved in 20 g of deionized water was added, and the pressure inside the reactor was increased to 0.83 MPaG with TFE. The total amount of water added to the reactor was 550 g. The solid content concentration of the water-soluble fluoropolymer obtained in the first polymerization was 0.21% by mass, and the melting point of the water-soluble fluoropolymer was 296.5°C. The polymerization rate of the first polymerization was 0.72 g / (hr·L). The radical generation ratio (B / A) at this time was 0.012.

[0333] A decrease in pressure was observed again, and thereafter, TFE was added to the reactor to maintain a constant pressure of 0.78 MPaG. When the amount of TFE consumed in the reaction reached 140 g, the supply of TFE was stopped, stirring was ceased, and the reaction was terminated. Subsequently, the reactor was evacuated until the pressure returned to atmospheric pressure, the contents were removed from the reactor and cooled, the separated paraffin was removed, and a PTFE aqueous dispersion was obtained. No polymer adhesion to the reactor was observed.

[0334] The obtained PTFE aqueous dispersion had a solid content concentration of 21.1% by mass and an average primary particle size of 199 nm. The obtained PTFE aqueous dispersion was diluted to a solid content concentration of 15% by mass using deionized water, and coagulation was performed by high-speed stirring to obtain a wet polymer. The obtained wet polymer was dried at 150°C for 18 hours to obtain PTFE powder.

[0335] The obtained PTFE powder had a standard specific gravity of 2.229 and a peak temperature of 333°C determined by DSC, indicating it was high molecular weight PTFE. Carboxylic acid / CF ２ The peak intensity ratio was 0.020, the thermal decomposition rate at high temperatures was 0.235%, the color L* value of the sample molded according to ASTM D4895-89 was 86.7, and the yellow index value was -9.2.

[0336] The extrusion pressure when the obtained PTFE powder was stretched was 17.1 MPa. The bead broke during stretching, so the stretch strength could not be measured.

[0337] Example 3 A SUS reactor with a stirrer and an internal volume of 6 L was charged with 180 g of paraffin, 0.011 g of 2-propanol as a chain transfer agent, 0.0021 g of A1315 (Harcross Chemicals, average molecular weight 860) as a nucleating agent, and 3500 g of deionized water, and then sealed. The reactor was then heated to 90°C while being suctioned and simultaneously purged with a TFE to remove oxygen from the reactor, and stirred at a speed of 260 rpm. 3.0 g of HFP was charged into the reactor and injected under pressure with a TFE until the pressure reached 0.78 MPaG. The reactor was kept at 90°C, the stirring speed was changed to 70 rpm, and then 0.36 g of APS dissolved in 10 g of deionized water was added, and the pressure in the reactor was increased to 0.83 MPaG with a TFE. One hour after adding APS, the pressure inside the reactor was 0.79 MPaG. 0.011 g of 2-propanol, 0.0021 g of A1315, and 0.358 g of APS were added again, and the reactor pressure was increased to 0.83 MPaG using TFE.

[0338] Two hours after the second addition of APS, the pressure inside the reactor was 0.80 MPaG. The reactor was evacuated to 0.10 MPaG. After another hour, the pressure inside the reactor was 0.10 MPaG. The reactor temperature was changed to 70°C, and the reactor was suctioned and simultaneously purged with TFE. The reactor was maintained at 70°C, and 4 hours and 30 minutes after the initial addition of APS, the stirring speed was changed to 260 rpm, and 3.0 g of HFP was added, followed by 0.036 g of APS dissolved in 20 g of deionized water, and the reactor pressure was increased to 0.83 MPaG using TFE. The total amount of water added to the reactor was 3600 g. The solid content concentration of the water-soluble fluoropolymer obtained in the first polymerization was 0.17% by mass, and the melting point of the water-soluble fluoropolymer was 300.1°C. The polymerization rate was 0.49 g / (hr·L). The radical generation ratio (B / A) at this time was 0.008.

[0339] A decrease in pressure was observed again, and thereafter TFE was added to the reactor to maintain a constant pressure of 0.78 MPaG. When the amount of TFE consumed in the reaction reached 180 g, the reactor was evacuated to 0.1 MPaG, and then TFE was added to raise the pressure to 0.83 MPaG. Thereafter, the pressure was maintained at a constant 0.78 MPaG. When the amount of TFE consumed in the reaction reached approximately 900 g, the supply of TFE was stopped, stirring was stopped, and the reaction was terminated. After that, the reactor was evacuated until the pressure returned to atmospheric pressure, the contents were removed from the reactor and cooled, the separated paraffin was removed, and a PTFE aqueous dispersion was obtained. No polymer adhesion to the reactor was observed.

[0340] The obtained PTFE aqueous dispersion had a solid content concentration of 20.0% by mass and an average primary particle size of 169 nm.

[0341] The obtained PTFE aqueous dispersion was diluted to a solid content concentration of 15% by mass using deionized water, and coagulated by high-speed stirring to obtain a wet polymer. The obtained wet polymer was dried at 150°C for 18 hours to obtain PTFE powder.

[0342] The obtained PTFE powder had a standard specific gravity of 2.216 and a peak temperature of 335°C according to DSC, indicating that it was high molecular weight PTFE. Carboxylic acid / CF ２The peak intensity ratio was 0.010, the thermal decomposition rate at high temperatures was 0.194%, the color L* value of the sample molded according to ASTM D4895-89 was 86.5, and the yellow index value was 3.2.

[0343] When the obtained PTFE powder was stretched, the extrusion pressure was 21.3 MPa and the stretch strength was 17.5 N.

[0344] Example 4 A SUS reactor with a stirrer and an internal volume of 6 L was charged with 180 g of paraffin, 0.011 g of 2-propanol as a chain transfer agent, 0.0021 g of A1315 as a nucleating agent, and 3500 g of deionized water, and then sealed. The reactor was then heated to 90°C while being suctioned and simultaneously purged with a TFE to remove oxygen from the reactor, and stirred at a speed of 260 rpm. 3.0 g of HFP was charged into the reactor and injected under pressure with a TFE until the pressure reached 0.78 MPaG. The reactor was kept at 90°C, the stirring speed was changed to 70 rpm, and then 0.36 g of APS dissolved in 10 g of deionized water was added, and the pressure inside the reactor was increased to 0.83 MPaG with a TFE.

[0345] Two hours after adding APS, the pressure inside the reactor was 0.76 MPaG. The reactor was evacuated to 0.10 MPaG. After another hour, the pressure inside the reactor was 0.10 MPaG. The reactor temperature was changed to 70°C, and the reactor was suctioned and purged with TFE. The reactor was maintained at 70°C, and 3 hours and 35 minutes after the initial addition of APS, the stirring speed was changed to 260 rpm, and 0.3 g of HFP was added, followed by 0.018 g of APS dissolved in 20 g of deionized water, and the reactor pressure was increased to 0.83 MPaG with TFE. The total amount of water added to the reactor was 3600 g. The solid content concentration of the water-soluble fluoropolymer obtained in the first polymerization was 0.16 mass%, and the melting point of the water-soluble fluoropolymer was 299.4°C. The polymerization rate was 0.45 g / (hr·L). The radical generation ratio (B / A) at this time was 0.005.

[0346] A decrease in pressure was observed again, and thereafter TFE was added to the reactor to maintain a constant pressure of 0.78 MPaG. When the amount of TFE consumed in the reaction reached 180 g, the reactor was evacuated to 0.1 MPaG, and then the pressure was increased to 0.83 MPaG with TFE. Thereafter, the pressure was maintained at a constant 0.78 MPaG. When the amount of TFE consumed in the reaction reached 540 g, 0.9 g of ammonium laurate dissolved in 10 g of deionized water was added. Furthermore, when the amount of TFE consumed in the reaction reached 640 g, 1.8 g of ammonium laurate dissolved in 10 g of deionized water was added. When the amount of TFE consumed in the reaction reached approximately 1290 g, the supply of TFE was stopped, stirring was stopped, and the reaction was terminated. Thereafter, the reactor was evacuated until the pressure returned to atmospheric pressure, the contents were removed from the reactor and cooled, the separated paraffin was removed, and a PTFE aqueous dispersion was obtained. No polymer deposits were observed on the reactor.

[0347] The obtained PTFE aqueous dispersion had a solid content concentration of 26.7% by mass and an average primary particle size of 306 nm.

[0348] The obtained PTFE aqueous dispersion was diluted to a solid content concentration of 15% by mass using deionized water, and coagulated by high-speed stirring to obtain a wet polymer. The obtained wet polymer was dried at 240°C for 18 hours to obtain PTFE powder.

[0349] The obtained PTFE powder had a standard specific gravity of 2.167 and a peak temperature of 344°C according to DSC, indicating that it was high molecular weight PTFE. Carboxylic acid / CF ２ The peak intensity ratio was 0.019, the thermal decomposition rate at high temperatures was 0.051%, the color L* value of the sample molded according to ASTM D4895-89 was 90.6, and the yellow index value was -11.4.

[0350] When the obtained PTFE powder was stretched, the extrusion pressure was 21.6 MPa, the tensile strength was 33.9 N, and the stress relaxation time was 590 seconds.

[0351] Example 5 A SUS reactor with a stirrer and an internal volume of 6 L was charged with 180 g of paraffin, 0.011 g of 2-propanol as a chain transfer agent, 0.0021 g of A1315 as a nucleating agent, and 3500 g of deionized water, and then sealed. The reactor was then heated to 90°C while being suctioned and simultaneously purged with a TFE to remove oxygen from the reactor, and stirred at a speed of 260 rpm. 3.0 g of HFP was charged into the reactor and injected under pressure with a TFE until the pressure reached 0.78 MPaG. The reactor was kept at 90°C, the stirring speed was changed to 70 rpm, and then 0.36 g of APS dissolved in 10 g of deionized water was added, and the pressure inside the reactor was increased to 0.83 MPaG with a TFE.

[0352] Two hours after adding APS, the pressure inside the reactor was 0.78 MPaG. The reactor was evacuated to 0.10 MPaG. After another hour, the pressure inside the reactor was 0.10 MPaG. The reactor temperature was changed to 70°C, and the reactor was suctioned and purged with TFE. The reactor was maintained at 70°C, and 3 hours and 47 minutes after the initial addition of APS, the stirring speed was changed to 260 rpm, and 3.0 g of HFP was added, followed by 0.036 g of APS dissolved in 20 g of deionized water, and the reactor pressure was increased to 0.83 MPaG using TFE. The total amount of water added to the reactor was 3600 g. The solid content concentration of the water-soluble fluoropolymer obtained in the first polymerization was 0.12% by mass, and the melting point of the water-soluble fluoropolymer was 299.2°C. The polymerization rate was 0.31 g / (hr·L). The radical generation ratio (B / A) at this time was 0.008.

[0353] A decrease in pressure was observed again, and thereafter TFE was added to the reactor to maintain a constant pressure of 0.78 MPaG. When the amount of TFE consumed in the reaction reached 180 g, the reactor was evacuated to 0.1 MPaG, and then the pressure was increased to 0.83 MPaG with TFE. Thereafter, the pressure was maintained at a constant 0.78 MPaG. Next, when the amount of TFE consumed in the reaction reached 540 g, 1.8 g of ammonium laurate dissolved in 10 g of deionized water was added. Furthermore, when the amount of TFE consumed in the reaction reached 640 g, 1.8 g of ammonium laurate dissolved in 10 g of deionized water was added. When the amount of TFE consumed in the reaction reached approximately 1550 g, the supply of TFE was stopped, stirring was stopped, and the reaction was terminated. Thereafter, the reactor was evacuated until the pressure returned to atmospheric pressure, the contents were removed from the reactor and cooled, the separated paraffin was removed, and a PTFE aqueous dispersion was obtained. No polymer deposits were observed on the reactor.

[0354] The obtained PTFE aqueous dispersion had a solid content concentration of 30.4% by mass and an average primary particle size of 219 nm.

[0355] The obtained PTFE aqueous dispersion was diluted to a solid content concentration of 15% by mass using deionized water, and coagulated by high-speed stirring to obtain a wet polymer. The obtained wet polymer was dried at 240°C for 18 hours to obtain PTFE powder.

[0356] The obtained PTFE powder had a standard specific gravity of 2.175 and a peak temperature of 338°C determined by DSC, indicating it was high molecular weight PTFE. Carboxylic acid / CF ２ The peak intensity ratio was 0.017, the thermal decomposition rate at high temperatures was 0.034%, the color L* value of the sample molded according to ASTM D4895-89 was 90.2, and the yellow index value was -11.7.

[0357] When the obtained PTFE powder was stretched, the extrusion pressure was 23.5 MPa, the stretch strength was 33.3 N, and the stress relaxation time was 192 seconds.

[0358] Example 6 A SUS reactor with a stirrer and an internal volume of 6 L was charged with 180 g of paraffin, 0.011 g of 2-propanol as a chain transfer agent, 0.0021 g of A1315 as a nucleating agent, and 3500 g of deionized water, and then sealed. The reactor was then heated to 90°C while being suctioned and simultaneously purged with a TFE to remove oxygen from the reactor, and stirred at a speed of 260 rpm. 3.0 g of HFP was charged into the reactor and injected with a TFE until the pressure reached 0.78 MPaG. The reactor was kept at 90°C, the stirring speed was changed to 70 rpm, and then 0.36 g of APS dissolved in 10 g of deionized water was added, and the pressure inside the reactor was increased to 0.83 MPaG with a TFE.

[0359] Two hours after adding APS, the pressure inside the reactor was 0.78 MPaG. The reactor was evacuated to 0.10 MPaG. After another hour, the pressure inside the reactor was 0.10 MPaG. The reactor temperature was changed to 80°C, and the reactor was suctioned and purged with TFE. The reactor was maintained at 80°C, and 4 hours and 19 minutes after the initial addition of APS, the stirring speed was changed to 260 rpm, and 1.2 g of CTFE was added. Then, 0.022 g of APS dissolved in 20 g of deionized water and 0.282 g of disuccinate peroxide (DSP) dissolved in 20 g of deionized water were added, and the pressure inside the reactor was increased to 0.83 MPaG with TFE. The total amount of water added to the reactor was 3600 g. The solid content concentration of the water-soluble fluoropolymer obtained in the first polymerization was 0.12% by mass, and the melting point of the water-soluble fluoropolymer was 300.2°C. The polymerization rate was 0.27 g / (hr·L). The radical generation ratio (B / A) at this time was 0.277.

[0360] A decrease in pressure was observed again, and thereafter TFE was added to the reactor to maintain a constant pressure of 0.78 MPaG. When the amount of TFE consumed in the reaction reached 180 g, the reactor was evacuated to 0.1 MPaG, and then the pressure was increased to 0.83 MPaG with TFE. Thereafter, the pressure was maintained at a constant 0.78 MPaG. Next, when the amount of TFE consumed in the reaction reached 540 g, 1.8 g of ammonium laurate dissolved in 10 g of deionized water was added. Furthermore, when the amount of TFE consumed in the reaction reached 640 g, 1.8 g of ammonium laurate dissolved in 10 g of deionized water was added. When the amount of TFE consumed in the reaction reached 1260 g, the supply of TFE was stopped, stirring was stopped, and the reaction was terminated. After that, the reactor was evacuated until the pressure returned to atmospheric pressure, the contents were removed from the reactor and cooled, the separated paraffin was removed, and a PTFE aqueous dispersion was obtained. No polymer deposits were observed on the reactor.

[0361] The obtained PTFE aqueous dispersion had a solid content concentration of 26.4% by mass and an average primary particle size of 202 nm.

[0362] The obtained PTFE aqueous dispersion was diluted to a solid content concentration of 15% by mass using deionized water, and coagulated by high-speed stirring to obtain a wet polymer. The obtained wet polymer was dried at 240°C for 18 hours to obtain PTFE powder.

[0363] The obtained PTFE powder had a standard specific gravity of 2.188 and a peak temperature of 337°C according to DSC, indicating that it was high molecular weight PTFE. Carboxylic acid / CF ２ The peak intensity ratio was 0.016, and the color L* value of the sample molded from the obtained PTFE powder according to ASTM D4895-89 was 91.9, and the yellow index value was -6.8. The thermal decomposition rate at high temperatures was 0.118%.

[0364] When the obtained PTFE powder was stretched, the extrusion pressure was 24.2 MPa, the stretch strength was 25.6 N, and the stress relaxation time was 166 seconds.

[0365] Example 7 A SUS reactor with a stirrer and an internal volume of 6 L was charged with 96 g of paraffin, 0.00165 g of Pronon #104 (manufactured by NOF Corporation, average molecular weight 1670), a fluorine-free nonionic surfactant, and 3280 g of deionized water as a nucleating agent, and then sealed. The reactor was then heated to 90°C while being suctioned and simultaneously purged with a TFE to remove oxygen from the reactor, and stirred at a speed of 250 rpm. 3.0 g of HFP was charged into the reactor and injected under pressure with a TFE until the pressure reached 0.78 MPaG. The reactor was kept at 90°C, the stirring speed was changed to 90 rpm, and then 0.33 g of ammonium persulfate (APS) dissolved in 10 g of deionized water was added, and the pressure inside the reactor was increased to 0.83 MPaG with a TFE.

[0366] Two hours after adding APS, the pressure inside the reactor was 0.73 MPaG. The reactor was evacuated to 0.10 MPaG. After another hour, the pressure inside the reactor was 0.10 MPaG. The reactor temperature was changed to 70°C, and the contents of the reactor were aspirated and simultaneously purged with TFE. The reactor was maintained at 70°C, and after adding 0.13 g of propane, 3 hours and 42 minutes after the initial addition of APS, the stirring speed was changed to 250 rpm, and at the same time, 0.33 g of APS dissolved in 20 g of deionized water was added, and the pressure inside the reactor was raised to 0.83 MPaG with TFE. The total amount of water added to the reactor was 3300 g. The solid content concentration of the water-soluble fluoropolymer obtained in the first polymerization was 0.24 mass%, and the melting point of the water-soluble fluoropolymer was 301.9°C. The polymerization rate was 0.71 g / (hr·L). The radical generation ratio (B / A) at this time was 0.067.

[0367] A decrease in pressure was observed again, and thereafter, TFE was added to the reactor to maintain a constant pressure of 0.78 MPaG. When the amount of TFE consumed in the reaction reached 660 g, the supply of TFE was stopped, stirring was ceased, and the reaction was terminated. Subsequently, the reactor was evacuated until the pressure returned to atmospheric pressure, the contents were removed from the reactor and cooled, the separated paraffin was removed, and a PTFE aqueous dispersion was obtained. No polymer adhesion to the reactor was observed.

[0368] The obtained PTFE aqueous dispersion had a solid content concentration of 16.2% by mass and an average primary particle size of 193 nm. The obtained PTFE aqueous dispersion was diluted to a solid content concentration of 15% by mass using deionized water, and coagulation was performed by high-speed stirring to obtain a wet polymer. The obtained wet polymer was dried at 100°C for 18 hours to obtain low molecular weight PTFE powder.

[0369] The obtained low molecular weight PTFE powder showed a peak temperature of 328°C and a melt viscosity of 22800 Pa·s by DSC analysis, confirming it was low molecular weight PTFE. Carboxylic acid / CF ２ The peak intensity ratio was 0.023.

[0370] A grease was prepared using the obtained low molecular weight PTFE powder, and after being held at 200°C for 30 minutes, the L* value of the grease was 80.4.

[0371] Comparative Example 1 A glass reactor with a stirrer and an internal volume of 1 L was charged with 27.5 g of paraffin, 0.00033 g of Pronon #104 (manufactured by NOF Corporation, average molecular weight 1670), a fluorine-free nonionic surfactant, and 520 g of deionized water as a nucleating agent, and then sealed. The reactor was then heated to 90°C while being suctioned and simultaneously purged with a TFE to remove oxygen from the reactor, and stirred at a speed of 550 rpm. 0.5 g of HFP was charged into the reactor and injected under pressure with a TFE until the pressure reached 0.78 MPaG. The reactor was kept at 90°C, and 0.11 g of ammonium persulfate (APS) dissolved in 10 g of deionized water was added, and the pressure inside the reactor was increased to 0.83 MPaG with a TFE.

[0372] After APS was added, a decrease in pressure was observed, and TFE was subsequently added to the reactor to maintain a constant pressure of 0.78 MPaG. The entire contents solidified before the amount of TFE consumed in the reaction reached 110 g, and it was not possible to obtain an aqueous dispersion.

[0373] Example 8 A 6 L volume SUS reactor was charged with 180 g of paraffin, 6.4 g of formic acid as a nucleating agent, and 3500 g of deionized water, and then sealed. The reactor was then heated to 85°C while simultaneously being suctioned and purged with a TFE to remove oxygen from the reactor, and stirred at a speed of 260 rpm. The reactor was then injected with a TFE until the pressure reached 0.78 MPaG. The reactor temperature was maintained at 85°C, the stirring speed was changed to 70 rpm, and then 0.36 g of APS dissolved in 10 g of deionized water was added, and the pressure in the reactor was increased to 0.83 MPaG with a TFE.

[0374] Three hours after adding APS, the pressure inside the reactor was 0.76 MPaG. The reactor temperature was changed to 70°C, and the contents of the reactor were aspirated and simultaneously purged with TFE. The reactor temperature was maintained at 70°C, and 3 hours and 3 minutes after adding APS, the stirring speed was changed to 260 rpm, and at the same time, 0.0179 g of APS dissolved in 20 g of deionized water was added, and the pressure inside the reactor was increased to 0.83 MPaG with TFE. The total amount of water added to the reactor was 3580 g. The solid content concentration of the water-soluble fluoropolymer obtained in the first polymerization was 0.31 mass%, and the melting point of the water-soluble fluoropolymer was 302.7°C. The polymerization rate of the first polymerization was 0.51 g / (hr·L). The radical generation ratio (B / A) at this time was 0.023.

[0375] A decrease in pressure was observed again, and thereafter, TFE was added to the reactor to maintain a constant pressure of 0.78 MPaG. When the amount of TFE consumed in the reaction reached approximately 900 g, the supply of TFE was stopped, stirring was halted, and the reaction was terminated. Subsequently, the reactor was evacuated until the pressure returned to atmospheric pressure, the contents were removed from the reactor and cooled, the separated paraffin was removed, and a PTFE aqueous dispersion was obtained. No polymer adhesion to the reactor was observed.

[0376] The obtained PTFE aqueous dispersion had a solid content concentration of 20.1% by mass and an average primary particle size of 202 nm.

[0377] The obtained PTFE aqueous dispersion was diluted to a solid content concentration of 15% by mass using deionized water, and coagulated by high-speed stirring to obtain a wet polymer. The obtained wet polymer was dried at 150°C for 18 hours to obtain PTFE powder.

[0378] The obtained PTFE powder had a standard specific gravity of 2.198 and a peak temperature of 338°C according to DSC, indicating that it was high molecular weight PTFE. Carboxylic acid / CF ２ The peak intensity ratio was 0.010, the thermal decomposition rate at high temperatures was 0.199%, the color L* value of the sample molded according to ASTM D4895-89 was 89.3, and the yellow index value was -5.0.

[0379] When the obtained PTFE powder was stretched, the extrusion pressure was 21.3 MPa and the stretch strength was 19.7 N.

[0380] Example 9 <Preparation of raw material solution A by first polymerization> 3309 g of deionized water was placed in a 6.0 L stainless steel pressure-resistant reaction vessel, the reactor was sealed, and while heating to 70°C, suction was applied and the reactor was purged with TFE to remove oxygen from the reactor, and the contents were stirred. Then, 245.0 g of perfluoro(methyl vinyl ether) (PMVE) was placed in the reactor. The temperature was raised to 90°C while stirring at 70 rpm, 32.4 g of TFE was placed in the reactor, and the pressure was increased to 1.65 MPa. Next, 0.83 g of ammonium persulfate (APS) dissolved in 10 g of deionized water was added as an initiator to start polymerization. As polymerization began, the pressure in the reactor decreased, so TFE was added to maintain a constant pressure of 1.65 MPa. Three hours after the addition of APS, stirring was stopped and the reaction was terminated. At this time, the amount of TFE added was 8 g. Subsequently, the reactor was evacuated until the pressure returned to atmospheric pressure, and the contents were removed from the reactor and cooled to obtain raw material liquid A. The polymerization rate of the first polymerization was 0.64 g / (hr·L), and the glass transition temperature of the water-soluble fluoropolymer obtained in the first polymerization was -8.5°C.

[0381] <Preparation of Raw Material Solution B> 127 g of AmberLite HPR650H (DuPont, cation exchange resin) was added to 3100 g of Raw Material Solution A. 60 minutes after starting stirring, the raw material solution and ion exchange resin were filtered off. 127 g of Purolite A300 (Purolite, anion exchange resin) was added to the filtered raw material solution. 60 minutes after starting stirring, the raw material solution and ion exchange resin were filtered off to obtain Raw Material Solution B. The solid content concentration of Raw Material Solution B was 0.56%.

[0382] <Preparation of aqueous dispersion (A) by second polymerization> 1158 g of deionized water, 2442 g of raw material solution B, and 180 g of paraffin wax were charged into a 6.0 L stainless steel pressure reactor. The reactor was sealed and heated to 70°C while suction was applied, and the reactor was purged with TFE to remove oxygen, and the contents were stirred at 160 rpm. 0.205 g of disuccinate oxide (DSAP) dissolved in 10 g of deionized water was added, and the reactor pressure was increased to 1.76 MPaG using TFE. A decrease in pressure was observed, and the radical generation ratio (B / A) at this time was 0.026. Thereafter, TFE was added to the reactor to maintain the pressure at 1.76 MPaG. When the amount of TFE consumed in the reaction reached 900 g, the supply of TFE was stopped, stirring was stopped, and the reaction was terminated. Subsequently, the reactor was evacuated until the pressure returned to atmospheric pressure, the contents were removed from the reactor and cooled, and the separated paraffin was removed to obtain PTFE aqueous dispersion (A).

[0383] The obtained PTFE aqueous dispersion (A) had a solid content concentration of 20.0% by mass and an average primary particle size of 202 nm. The obtained PTFE aqueous dispersion was diluted to a solid content concentration of 15% by mass using deionized water, and coagulation was performed by high-speed stirring to obtain a wet polymer. The obtained wet polymer was dried at 180°C for 18 hours to obtain PTFE powder.

[0384] The obtained PTFE powder had a standard specific gravity of 2.152 and a peak temperature of 338°C according to DSC, indicating that it was high molecular weight PTFE. Carboxylic acid / CF ２The peak intensity ratio was 0.006, the thermal decomposition rate at high temperatures was 0.44%, the color L* value of the sample molded according to ASTM D4895-89 was 88.1, and the yellow index value was 2.3.

[0385] When the obtained PTFE powder was stretched, the extrusion pressure was 25.7 MPa and the stretch strength was 15.4 N.

Claims

(1) Prepare an aqueous solution containing a water-soluble fluoropolymer by carrying out a first polymerization of a fluoromonomer in the presence of an aqueous medium and a polymerization initiator, substantially in the absence of a fluorine-containing surfactant. (2) A aqueous dispersion containing a fluororesin is prepared by carrying out a second polymerization of a fluoromonomer in the presence of the aqueous solution, substantially in the absence of a fluorine-containing surfactant. A method for producing an aqueous dispersion of fluororesin, The content of the water-soluble fluoropolymer in the aqueous solution is greater than 0% by mass and less than 1.0% by mass, relative to the mass of the aqueous solution. The fluororesin content in the aqueous dispersion is 15% by mass or more relative to the mass of the aqueous dispersion. The polymerization rate of the first polymerization is 3.0 g / (hr·L) or less. From the start of the second polymerization, the second polymerization is carried out in substantially the absence of a fluorine-free anionic surfactant until the content of the fluororesin in the aqueous dispersion reaches 10% by mass relative to the mass of the aqueous dispersion. Manufacturing method. 　 The manufacturing method according to claim 1, wherein the fluoromonomer in the first polymerization comprises at least tetrafluoroethylene. 　 The manufacturing method according to claim 1 or 2, wherein the melting point of the water-soluble fluoropolymer is 250 to 330°C, or the glass transition temperature of the water-soluble fluoropolymer is 10°C or less. 　 The manufacturing method according to any one of claims 1 to 3, wherein a polymerization initiator is added in the second polymerization. (1) Prepare an aqueous solution containing a water-soluble fluoropolymer by carrying out a first polymerization of a fluoromonomer in the presence of an aqueous medium and a polymerization initiator, substantially in the absence of a fluorine-containing surfactant. (2) A aqueous dispersion containing a fluororesin is prepared by carrying out a second polymerization of a fluoromonomer in the presence of the aqueous solution, substantially in the absence of a fluorine-containing surfactant. A method for producing an aqueous dispersion of fluororesin, The content of the water-soluble fluoropolymer in the aqueous solution is greater than 0% by mass and less than 1.0% by mass, relative to the mass of the aqueous solution. The fluororesin content in the aqueous dispersion is 15% by mass or more relative to the mass of the aqueous dispersion. The ratio of radical generation (B / A) calculated by the following formula is 0.7 or less. Manufacturing method. The ratio of radical generation (B / A) = B / A A: Radical generation per gram of aqueous medium per minute from the initial addition of the polymerization initiator for the first polymerization (A) (mol / (g・min)) B: Radical generation per gram of aqueous medium in the first minute from the start of the second polymerization (B) (mol / (g・min)) The method for producing the product according to claim 5, wherein the fluoromonomer comprises at least tetrafluoroethylene. 　 The manufacturing method according to claim 5 or 6, wherein the polymerization rate of the first polymerization is 3.0 g / (hr·L) or less. 　 The manufacturing method according to any one of claims 5 to 7, wherein the melting point of the water-soluble fluoropolymer is 250 to 330°C, or the glass transition temperature of the water-soluble fluoropolymer is 10°C or less. 　 The manufacturing method according to any one of claims 5 to 8, wherein a polymerization initiator is further added in the second polymerization. (1) Prepare an aqueous solution containing a water-soluble fluoropolymer by carrying out a first polymerization of a fluoromonomer in the presence of an aqueous medium and a polymerization initiator, substantially in the absence of a fluorine-containing surfactant. (2) A aqueous dispersion containing a fluororesin is prepared by carrying out a second polymerization of a fluoromonomer in the presence of the aqueous solution, substantially in the absence of a fluorine-containing surfactant. A method for producing an aqueous dispersion of fluororesin, The content of the water-soluble fluoropolymer in the aqueous solution is greater than 0% by mass and less than 1.0% by mass, relative to the mass of the aqueous solution. The fluororesin content in the aqueous dispersion is 15% by mass or more relative to the mass of the aqueous dispersion. In the first polymerization, the polymerization initiator present is a thermal decomposition type radical polymerization initiator, and the first polymerization is initiated by adding the polymerization initiator, and the first polymerization continues until 90% or more by mass of the initially added polymerization initiator has decomposed. The melting point of the water-soluble fluoropolymer is 250 to 330°C, or the glass transition temperature of the water-soluble fluoropolymer is 10°C or less. From the start of the second polymerization, the second polymerization is carried out in substantially the absence of a fluorine-free anionic surfactant until the content of the fluororesin in the aqueous dispersion reaches 10% by mass relative to the mass of the aqueous dispersion. Manufacturing method. 　 The manufacturing method according to claim 10, wherein the fluoromonomer in the first polymerization comprises at least tetrafluoroethylene. 　 The manufacturing method according to claim 10 or 11, wherein the polymerization rate of the first polymerization is 3.0 g / (hr·L) or less. 　 The manufacturing method according to any one of claims 10 to 12, wherein a polymerization initiator is added in the second polymerization. 　 Fluororesin, It contains virtually no fluorine-containing surfactants. The average primary particle diameter is 500 nm or less. In accordance with ASTM D4895-89, the color L* value of the test specimen made from the fluororesin is greater than 60. Carboxylic acid / CF measured by infrared spectroscopy ２ The peak intensity ratio is 0.0050 or higher. Fluororesin. 　 The fluororesin according to claim 14, wherein the standard specific gravity is 2.230 or less. 　 The fluororesin according to claim 14 or 15, wherein the tensile strength is 15.0 N or more. 　 A fluororesin according to any one of claims 14 to 16, wherein the thermal decomposition rate at high temperatures is 0.030% or more, and the yellow index value is -20 to 20. 　 A fluororesin according to any one of claims 14 to 17, wherein the thermal decomposition rate at high temperatures is 0.030% or more, and the tensile strength is 15.0 N or more. 　 A fluororesin according to any one of claims 14 to 18 that is substantially free of fluorine-containing surfactants. 　 A fluororesin according to any one of claims 14 to 19, which does not contain a polymer (I) comprising a polymerization unit (I) substantially based on a monomer (I) represented by general formula (I). 　　　 General form (I): CX １ X ３ =CX ２ R(-CZ) １ Z ２ -A ０ ) ｍ (wherein X １ and X ３ are each independently F, Cl, H or CF ３ ; X ２ is H, F, an alkyl group or a fluorine-containing alkyl group; A ０ is an anionic group; R is a linking group; Z １ and Z ２ are each independently H, F, an alkyl group or a fluorine-containing alkyl group; m is an integer of 1 or more.). 　 It contains virtually no fluorine-containing surfactants. The average primary particle diameter is 500 nm or less. The color tone L* value of the grease prepared by mixing it with lubricating oil is greater than 60 after being held at 200°C for 30 hours. Low molecular weight polytetrafluoroethylene. Carboxylic acid / CF measured by infrared spectroscopy ２ The low molecular weight polytetrafluoroethylene according to claim 21, wherein the peak intensity ratio is 0.0050 or more.

Images