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

Abstract

To provide a method for producing an aqueous dispersion of fluororesin that can be manufactured without using fluorine-containing surfactants, while suppressing the adhesion of the generated polymer to the reactor. [Solution] A method for producing an aqueous dispersion of 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 the fluoromonomer in the presence of the aqueous solution, 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.

Description

[Technical Field]

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

[0002] Patent Document 1 contains: 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. The aforementioned initial period is: The process includes preparing an initial dispersion of fluoropolymer particles in the aqueous medium in the polymerization reactor, The aforementioned stabilization period is: The process involves polymerizing fluoromonomers in the polymerization reactor, The step includes adding a hydrocarbon-containing surfactant to the polymerization reactor, A method in which no fluorine-based surfactant is added during the aforementioned stabilization period. It is stated. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] International Publication No. 2012 / 064841 [Overview of the project] [Problems that the invention aims to solve]

[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. [Means for solving the problem]

[0005] According to this disclosure, (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 the substantially 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. A manufacturing method is provided. [Effects of the Invention]

[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. [Modes for carrying out the invention]

[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, it is preferable that the fluororesin (excluding polytetrafluoroethylene) is 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 ranges represented by endpoints include 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 1" includes all numbers greater than or equal to 1 (for example, at least 2, at least 4, at least 6, at least 8, at least 10, 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 is, (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 the substantially 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. This is a manufacturing method (hereinafter sometimes referred to as "the first manufacturing method of this disclosure").

[0018] Furthermore, this disclosure is, (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. This is a manufacturing method (hereinafter sometimes referred to as "the second manufacturing method of this disclosure"). The ratio of radical generation (B / A) = B / A A: Radical generation rate 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 rate per gram of aqueous medium per minute from the start of the second polymerization (B) (mol / (g·min))

[0019] Furthermore, this disclosure is, (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 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. From the start of the second polymerization, the second polymerization is carried out in the substantially 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. This is a manufacturing method (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 this disclosure, (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.

[0023] In the first 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.

[0024] In this disclosure, a water-soluble fluoropolymer refers to a fluoropolymer whose particle size cannot be measured by dynamic light scattering (DLS). It is preferable that the particle size of the water-soluble fluoropolymer cannot be measured even when it is contained in an aqueous solution at a content of 0.10% by mass. More preferably, it is preferable that the particle size cannot be measured even when the water-soluble fluoropolymer is contained in an aqueous solution at a content of 0.12% by mass, and even more preferably at 0.15% by mass. On the other hand, since fluororesins contained in an aqueous dispersion are not water-soluble, their particle size can be measured by dynamic light scattering (DLS).

[0025] In the first 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.

[0026] In this disclosure, the content of the water-soluble fluoropolymer in the aqueous solution is the value obtained by drying 1 g of the aqueous solution in a forced-air 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, 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. 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. 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 presence of a 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). The polymerization rate of the second polymerization 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. 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 this disclosure, (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.

[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. The ratio of radical generation (B / A) = B / A A: Radical generation rate 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 rate per gram of aqueous medium per minute from the start of the second polymerization (B) (mol / (g·min))

[0040] "The point at which the polymerization initiator for the first polymerization is first added" refers to the point at which the polymerization initiator is added to start the first polymerization, and is different from the point at which polymerization initiators are added additionally during the polymerization reaction. Furthermore, if polymerization is carried out in multiple stages, it refers to the point at which the polymerization initiator is added to start the first polymerization of the multiple stages, and is different from the point at which 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.

number

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

[0043] In the manufacturing method of the present disclosure, the ratio of radical generation amount (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 involves 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. 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 presence of a 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 this disclosure, (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.

[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 reacts with fluoromonomer molecules, 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 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. 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 presence of a 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 at least 90% by mass of the pyrolysis-type radical polymerization initiator, assuming that the initially added amount of pyrolysis-type radical polymerization initiator 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 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.

[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). The polymerization rate of the second polymerization 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. 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 collectively be 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 this disclosure, polymerization is carried out in substantially the absence of fluorine-containing surfactants 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 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] (Polymerization initiator) In one embodiment of the manufacturing method of this disclosure, a thermal decomposition-type radical polymerization initiator is used as the polymerization initiator. In particular, when a thermal decomposition-type radical polymerization initiator is used in the first polymerization in the first to third manufacturing methods, it becomes even easier to adjust the polymerization rate and the amount of decomposition of the polymerization initiator.

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

[0075] Examples of polymerization initiators and pyrolysis-type radical polymerization initiators include water-soluble radical polymerization initiators. Water-soluble radical polymerization initiators may be known water-soluble peroxides, such as ammonium salts, potassium salts, and sodium salts of persulfuric acid, perboric acid, perchloric acid, superphosphate, and percarbonate; organic peroxides such as disuccinate peroxide and diglutaric acid peroxide; t-butyl permalate; and t-butyl hydroperoxide. Among these, persulfates are preferred, with potassium persulfate (K2S2O8), ammonium persulfate ((NH4)2S2O8), and sodium persulfate (Na2S2O8) being more preferred, and ammonium persulfate being even more preferred.

[0076] In the second polymerization in the first to third manufacturing 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, ammonium cerium 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 or more by mass, even more preferably 50 ppm or more by mass, more preferably 3000 ppm or less by mass, and even more preferably 2000 ppm or less by mass, 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 initially added 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 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.

[0082] In the manufacturing method of this 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 or more by mass, even more preferably 80 ppm or more by mass, more preferably 3000 ppm or less by mass, and even more preferably 2000 ppm or less by mass, 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 this 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, the use of 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 typically 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 production method of the present disclosure, polymerization may be carried out in the presence of a nucleating agent. By adding a nucleating agent at the initial stage of polymerization, the average primary particle diameter of the particles contained in the aqueous dispersion becomes smaller, and an aqueous dispersion excellent in stability can be obtained.

[0093] Examples of the nucleating agent include monocarboxylic acids, dicarboxylic acids, perfluoropolyether (PFPE) acids or their salts, hydrocarbon-containing surfactants, etc. At least one selected from the group consisting of monocarboxylic acids, dicarboxylic acids, perfluoropolyether (PFPE) acids or their salts, and fluorine-free nonionic surfactants is preferable, and monocarboxylic acids or monocarboxylic acid salts are more preferable. Examples of the monocarboxylic acid or monocarboxylic acid salt include formic acid or formate.

[0094] Among them, fluorine-free nonionic surfactants are preferable as the nucleating agent. The fluorine-free nonionic surfactant preferably does not contain an aromatic moiety.

[0095] Examples of the fluorine-free nonionic surfactant include nonionic surfactants represented by general formula (i) and nonionic surfactants represented by general formula (ii). R 6 -O-A 1 -H (i) (In the formula, R 6 is a linear or branched primary or secondary alkyl group having 8 to 18 carbon atoms, and A 1 is a polyoxyalkylene chain.) R 7 -C6H4-O-A 2 -H (ii) (In the formula, R 7 is a linear or branched alkyl group having 4 to 12 carbon atoms, and A 2 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, BASF's Pluronic® R series (31R1, 17R2, 10R5, 25R4 (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, and Harcros Chemicals' T-Det Examples include the A series (A-138, A-139, A-1315, etc.) and Dispanol TOC manufactured by Nippon Oil & Fats Co., Ltd.

[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 the substantially 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 fluororesin content 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 Avanell S series (S-70, S-74, etc.).

[0107] As for fluorine-free anionic surfactants, R Z -(LM) x (In the formula, R Z However, this 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 -LM bonded to Rz and is an integer from 1 to 3. An anionic surfactant represented by ) is an example. R Z Preferably, the hydrocarbon group has 1 to 100 carbon atoms and may contain heteroatoms. The heteroatoms may be inserted between carbon atoms or may be included in substituents bonded to carbon atoms. L is -ArSO3 - , -SO3 - -SO4-, -PO3 - or -COO - This is preferable. -ArSO3- It is an aryl sulfonate. For M, H is a metal atom, NR is an NR 5Z 4. Preferably, imidazolium which may have substituents, pyridinium which may have substituents, or phosphonium which may have substituents. 5Z The element is preferably H or an organic group (preferably an alkyl group having 1 to 3 carbon atoms). More specifically, the anionic surfactants listed below are examples.

[0108] As for fluorine-free anionic surfactants, R Z -LM (where R Z However, it is a monovalent organic group containing one or more carbon atoms. L is -ArSO3 - , -SO3 - -SO4-, -PO3 - or -COO - And M is H, a metal atom, NR 5Z 4. Imidazolium which may have substituents, pyridinium which may have substituents, or phosphonium which may have substituents, R 5Z is H or an organic group, -ArSO3 - Anionic surfactants, represented by aryl sulfonates, are also examples. Specifically, CH3-(CH2) compounds such as lauric acid and lauryl sulfate (dodecyl sulfate) n Examples include those expressed by -LM (where n is an integer between 6 and 17, and L and M are the same as above). R 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. R Z However, it is preferable that the alkyl group has 3 to 18 carbon atoms. R ZHowever, mixtures of alkyl groups having 12 to 16 carbon atoms, where LM is a sulfate, can also be used.

[0109] Other compounds with surfactant properties include R 6Z (-LM)2(wherein, R 6Z However, it is a monovalent organic group containing one or more carbon atoms. L is -ArSO3 - , -SO3 - -SO4-, -PO3 - or -COO - And M is H, a metal atom, NR 5Z 4. Imidazolium which may have substituents, pyridinium which may have substituents, or phosphonium which may have substituents, R 5Z is H or an organic group, -ArSO3 - Anionic surfactants, represented by aryl sulfonates, are also examples. R 6Z However, it may be a linear or branched alkylene group having 1 or more carbon atoms, which may have substituents, or a cyclic alkylene group having 3 or more carbon atoms, which may have substituents. 6Z If the alkylene group has three or more carbon atoms, it may contain a monovalent or divalent heterocycle, or it may form a ring.

[0110] As for fluorine-free anionic surfactants, R 7Z (-LM)3(wherein, R 7Z However, it is a monovalent organic group containing one or more carbon atoms. L is -ArSO3 - , -SO3 - -SO4-, -PO3 - or -COO - And M is H, a metal atom, NR 5Z 4. Imidazolium which may have substituents, pyridinium which may have substituents, or phosphonium which may have substituents, R 5Z is either H or an organic group. -ArSO3 - Anionic surfactants, represented by aryl sulfonates, are also examples. R7Z may be a linear or branched alkylidine group having 1 or more carbon atoms which may have a substituent, or a cyclic alkylidine group having 3 or more carbon atoms which may have a substituent. R 7Z When the alkylidine group of R has 3 or more carbon atoms, it may contain a monovalent or divalent heterocyclic ring or may form a ring. The above R 5z is preferably H or an alkyl group, more preferably H or an alkyl group having 1 to 10 carbon atoms, and still more preferably H or an alkyl group having 1 to 4 carbon atoms.

[0111] In the present disclosure, unless otherwise specified, "substituent" means a group that can be substituted. Examples of the "substituent" include an aliphatic group, an aromatic group, a heterocyclic group, an acyl group, an acyloxy group, an acylamino group, an aliphatic oxy group, an aromatic oxy group, a heterocyclic oxy group, an aliphatic oxycarbonyl group, an aromatic oxycarbonyl group, a heterocyclic oxycarbonyl group, a carbamoyl group, an aliphatic sulfonyl group, an aromatic sulfonyl group, a heterocyclic sulfonyl group, an aliphatic sulfonyloxy group, an aromatic sulfonyloxy group, a heterocyclic sulfonyloxy group, a sulfamoyl group, an aliphatic sulfonamide group, an aromatic sulfonamide group, a heterocyclic sulfonamide group, an amino group, an aliphatic amino 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 carboxy 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 di-aliphatic oxyphosphinyl group, or a di-aromatic oxyphosphinyl group.

[0112] Examples of the fluorine-free anionic surfactant also include a siloxane hydrocarbon-based surfactant. The siloxane hydrocarbon-based surfactant is 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 (Clariant's Emulsogen® SB10) and sodium diisotridecyl sulfosuccinate (Cesapinia Chemicals' Polilol® TR / LNA).

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

[0115] Examples of fluorine-free anionic surfactants include those with the general formula (1): [ka] (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 the general formula: -YR 6 The base indicated by, R 2 and R 5 Of these, at least one is a base represented by the general formula: -XA, or the general formula: -YR 6 It represents the base indicated by . Furthermore, X is a divalent linking group or bond, identical or different in each occurrence; A is the same or different in each occurrence as -COOM, -SO3M, or -OSO3M (where M is H, a metal atom, NR). 7 4. Imidazolium which may have substituents, pyridinium which may have substituents, or phosphonium which may have substituents, R 7 (This refers to H or an organic group). Y is the same or different in each occurrence, -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 is H or an organic group; R 6 This is 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 carbon atoms, either identically or differently in each occurrence; It represents. R 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 a preferred example.

[0116] Let's explain surfactants (1).

[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 the general formula: -YR 6 The base indicated by, R 2 and R 5 Of these, at least one is a base represented by the general formula: -XA, or the general formula: -YR 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 1 The alkyl group described above preferably does not contain a carbonyl group. Up to 75% of the hydrogen atoms bonded to the carbon atoms of the above alkyl group may be substituted by halogen atoms, up to 50% may be substituted by halogen atoms, and up to 25% may be substituted by halogen atoms. However, it is preferably a non-halogenated alkyl group that does not contain halogen atoms such as fluorine atoms and chlorine atoms. The above alkyl group preferably has no substituents.

[0120] R 1 Preferably, it is a linear or branched alkyl group having 1 to 10 carbon atoms that may have a substituent or a cyclic alkyl group having 3 to 10 carbon atoms that may have a substituent. More preferably, it is 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, it is a linear or branched alkyl group having 1 to 10 carbon atoms that has no substituents. Even more preferably, it is a linear or branched alkyl group having 1 to 3 carbon atoms that has no substituents. Particularly preferably, it is a methyl group (-CH3) or an ethyl group (-C2H5), and most preferably, it is a methyl group (-CH3).

[0121] Examples of the monovalent substituent include a group represented by the general formula: -Y-R 6 a group represented by the general formula: -X-A, -H, an alkyl group of C 1-20 , -NH2, -NHR 9 (R 9 is an organic group), -OH, -COOR 9 (R 9 is an organic group) or -OR 9 (R 9 (R

[0122] R 9 Preferably, it is an alkyl group of C 1-10 or an alkylcarbonyl group of C 1-10 . More preferably, it is an alkyl group of C 1-4 or an alkylcarbonyl group of C 1-4 .

[0123] In the formula, X represents a divalent linking group or bond, which may be the same or different in each occurrence. R 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 can be -CO-, -S(=O)2-, -O-, -COO-, -OCO-, -S(=O)2-O-, -OS(=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 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, -SO3M, or -OSO3M (where M is H, a metal atom, NR). 7 4. Imidazolium which may have substituents, pyridinium which may have substituents, or phosphonium which may have substituents, 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 groups are preferred as organic groups in R. 7 For example, H or C 1-10 The organic group is preferably H or C1-4 The organic group is more preferably H or C 1-4 A alkyl group is even more preferred. Examples of the above-mentioned metal atoms include alkali metals (Group 1) and alkaline earth metals (Group 2), with Na, K, or Li being preferred.

[0128] For M, H, metal atoms, or NR 7 4 is preferred, and H, alkali metals (Group 1), alkaline earth metals (Group 2), or NR 7 4 is more preferred, H, Na, K, Li or NH4 is even more preferred, Na, K or NH4 is even more preferred, Na or NH4 is particularly preferred, and NH4 is most preferred.

[0129] In the formula, Y is the same or different in each occurrence, -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 can be a combination of -O-, -COO-, -OCO-, -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 groups are preferred as 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 As for, General formula:-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 indicated by, or General formula:-R 10 -CONR 8 -R 11 The base shown by (In the formula, R 8 R represents H or an organic group. 10 is an alkylene group, R 11 (where is an alkyl group which may have substituents) is preferred. R 6 For example, the general formula is: -R10 -CO-R 11 The group indicated by is more preferable.

[0135] R 8 Alkyl groups are preferred as 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. 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 -XA, where A is -COOM.

[0139] As for fluorine-free anionic surfactants, see formula (1-0A): [ka] (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 the general formula: -X A -A represents the base indicated by -A. X A Each occurrence is identical or different, and consists of a divalent hydrocarbon group, formula: -N(R 6A )-R 7A -(R 6A is H or -CH2COOM (M is as described below), R 7A 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. Imidazolium which may have substituents, pyridinium which may have substituents, or phosphonium which may have substituents, R 7 (This refers to 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 number of carbon atoms in the monovalent hydrocarbon group, which may contain an ester group between carbon atoms, is preferably 1 to 50, and more preferably 5 to 20. 1A ~R 5A Any two of these may bond to each other to form a ring. A preferred monovalent hydrocarbon group is an alkyl group, which may contain an ester group between the carbon atoms. 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 be represented by A.

[0142] In the general formula (1-0A), a preferred embodiment is R 2A However, the general formula is: -X A -A is a group represented by 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 also R 2A However, the general formula is: -X A -A is a group represented by R 1A and R 3A ga-Y A -R 6 The group is represented by Y A In each occurrence, -COO-, -OCO-, or the combination R is identical or different. 6 In each occurrence, R is the same or different alkyl group having 1 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, and the like. 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), and Gemsurf α182 (14 carbon atoms).

[0145] In the general formula (1-0A), a preferred embodiment is also R 1A ga-Y A -R 6 The group is 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 X A However, the formula is: -N(R 6A )-R 7A -(R 6A is H or -CH2COOM (M is as described above), R 7A This embodiment is a group represented by an alkylene group (preferably a methylene group) having 1 to 5 carbon atoms. Examples of surfactants in this embodiment include 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 radical treatment described above is any treatment that generates radicals in a 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 oxidation treatment described above is a treatment 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 used for 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 -X X (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 -OSO3X X1 ,-COOX X1 or -SO3X 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 )) is H or an organic group, and may be the same or different. A surfactant represented by )) is preferred. XThe 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): [ka] (In the formula, R 1a R is a linear or branched alkyl group having 1 or more carbon atoms, or a cyclic alkyl group having 3 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 2 or more carbon atoms, it may contain a carbonyl group, and if there are 3 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), formula (b) below: [ka] (In the formula, R 1bR 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 these may bond to each other to form a ring. L can be a single bond, -CO2-B-*, -OCO-B-*, or -CONR 6b -B-*, -NR 6b CO-B-*, or -CO- (however, -CO2-B-, -OCO-B-, -CONR 6b -B-, -NR 6 Excluding the carbonyl group contained in CO-B-, 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 substituents. * is -OSO3X in the formula. b This refers to the side that binds to the surfactant (b) shown by the following formula (c): [ka] (In the formula, R 1cR is a linear or branched alkyl group having 1 or more carbon atoms, or a cyclic alkyl group having 3 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 2 or more carbon atoms, it may contain a carbonyl group, and if there are 3 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 -COOX c or -SO3X 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): [ka] (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, -SO3X d or -COOX d (X d H, metal atoms, NR 5d4. 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 these may bond to each other to form a ring. L can be a single bond, -CO2-B-*, -OCO-B-*, or -CONR 6d -B-*, -NR 6d CO-B-*, or -CO- (however, -CO2-B-, -OCO-B-, -CONR 6d -B-, -NR 6d Excluding the carbonyl group contained in CO-B-, 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. * 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 1 or more carbon atoms, or a cyclic alkyl group having 3 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 also contain the carbonyl group at its terminus. That is, acyl groups such as the acetyl group represented by CH3-C(=O)- are also included in the alkyl group. Furthermore, the alkyl group may include a monovalent or divalent heterocycle if it has three or more carbon atoms, or it may form a ring. The heterocycle is preferably an unsaturated heterocycle, more preferably an oxygen-containing unsaturated heterocycle, such as a furan ring. 1cIn 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, the group represented by CH3-C(=O)-CH2- has 3 carbon atoms, the group represented by CH3-C(=O)-C2H4-C(=O)-C2H4- has 7 carbon atoms, and the group represented by CH3-C(=O)- has 2 carbon atoms.

[0152] The alkyl group described above may have hydrogen atoms bonded to carbon atoms substituted with functional groups, for example, with monovalent organic groups including a hydroxyl group (-OH) or an ester bond, but it is preferable that it is not substituted with any functional group. The monovalent organic group containing the above ester bond is given by formula: -OC(=O)-R 101c (In the formula, R 101c Examples of groups are those represented by an alkyl group. The alkyl group described above 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 3c These are independently single or divalent linking groups. R 2c and R 3c Preferably, these are independently single-bonded or linear or branched alkylene groups having 1 or more carbon atoms, or cyclic alkylene groups having 3 or more carbon atoms. R 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 above ester bond is given by formula: -OC(=O)-R 102c (In the formula, R 102c Examples of groups are those represented by an alkyl group. The alkylene group described above 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. R 1c , R 2c and R 3c Any two of them may be joined together to form a ring.

[0156] In formula (c), in formula, A c -COOX c or -SO3X 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.) c For example, -COOX c R is preferable. 4c Alkyl groups are preferred as organic groups in R.4c The metal atom is preferably 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. The metal atom can be a monovalent or divalent metal atom, such as alkali metals (Group 1) or alkaline earth metals (Group 2), with Na, K, or Li being preferred. X c Examples include H, alkali metals (Group 1), alkaline earth metals (Group 2), or NR 4c 4 is preferred, H, Na, K, Li or NH4 is more preferred because it is easily soluble in water, Na, K or NH4 is even more preferred because it is even more soluble in water, Na or NH4 is particularly preferred, and NH4 is most preferred because it is easily removed. c When the surfactant is NH4, the solubility of the surfactant in aqueous media is excellent, 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 1 or more carbon atoms, which may have substituents, or a cyclic alkyl group having 3 or more carbon atoms, which may have substituents. The alkyl group described above may include a monovalent or divalent heterocycle if it has three or more carbon atoms, or it may form a ring. The heterocycle is preferably an unsaturated heterocycle, more preferably an oxygen-containing unsaturated heterocycle, such as a furan ring. 1d 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.

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

[0160] R 1dThe 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 described above 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. Preferably, the alkyl group described above does not have any substituents.

[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 is preferred. Even more preferably, a linear or branched alkyl group having 1 to 10 carbon atoms without substituents is preferred, and even more preferably, a linear or branched alkyl group having 1 to 3 carbon atoms without substituents is preferred. A methyl group (-CH3) or an ethyl group (-C2H5) is particularly preferred, and a methyl group (-CH3) is most preferred.

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

[0164] R 2d and R 4dThe 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, and 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. Preferably, the alkyl group described above does not have any substituents.

[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; even more preferably a linear or branched alkyl group having 1 to 3 carbon atoms that does not have substituents; and particularly preferably a methyl group (-CH3) or an ethyl group (-C2H5).

[0167] R 2d and R 4d Preferably, the 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, H or a linear or branched alkyl group having 1 to 3 carbon atoms that does not have a substituent; even more preferably, H, a methyl group (-CH3), or an ethyl group (-C2H5); and particularly preferably, H.

[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 described above 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. Preferably, the alkylene group described above does not have any substituents.

[0170] The alkylene group described above 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, it is a linear or branched alkylene group having 1 to 10 carbon atoms that does not contain a carbonyl group, or a cyclic alkylene group having 3 to 10 carbon atoms that does not contain a carbonyl group. More preferably, it is a linear or branched alkylene group having 1 to 10 carbon atoms that does not have substituents, and even more preferably, it is a methylene group (-CH2-), an ethylene group (-C2H4-), an isopropylene group (-CH(CH3)CH2-), or a propylene group (-C3H6-).

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

[0172] In equation (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 equation (d), p and q are independent 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. More preferably, 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, -SO3X 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.) d For example, -COOX d R is preferable. 5d Alkyl groups are preferred as 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 1- and 2-valent 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 the case. X d Examples include H, alkali metals (Group 1), alkaline earth metals (Group 2), or NR 5d 4 is preferred, H, Na, K, Li or NH4 is more preferred because it is easily soluble in water, Na, K or NH4 is even more preferred because it is even more soluble in water, Na or NH4 is particularly preferred, and NH4 is most preferred because it is easily removed. d When the surfactant is NH4, the solubility of the surfactant in aqueous media is excellent, and metal components are less likely to remain in the polymer or the final product.

[0176] In equation (d), L is a single bond, -CO2-B-*, -OCO-B-*, -CONR 6d -B-*, -NR 6d CO-B-*, or -CO- (however, -CO2-B-, -OCO-B-, -CONR 6d -B-, -NR 6d Excluding the carbonyl group contained in CO-B-, 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 for fluorine-free anionic surfactants, see formula I below: R-(XZ) n (I) Compound I, represented by (wherein R is a hydrophobic hydrocarbon moiety containing one or more saturated or unsaturated, acyclic or cyclic aliphatic groups. The percentage of the total CH3 groups relative to the total CH3, CH2 and CH groups in one or more aliphatic groups is at least about 70%, and the hydrophobic moiety does not contain siloxane units. Each X may be the same or different and represents an ionic hydrophilic moiety. Each Z may be the same or different and represents one or more counterions of the ionic hydrophilic moiety. n is 1 to 3.), 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: [ka] (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: [ka] (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’’ The percentage of CH3 groups relative to the total of CH3, CH2, and CH groups in the group is at least about 70%, or R 2’ and R 2’’ These groups may bond together to form saturated or unsaturated aliphatic rings that may contain ether or ester bonds, provided that the percentage of CH3 groups relative to the total CH3, CH2, and CH groups in the ring is at least about 70%. 1 Y is hydrogen, methoxy, ethoxy, or phenoxy. + It is preferably compound II represented by ( ).

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

[0183] Compound I is given by the following formula III: [ka] (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’’ The percentage of CH3 in the total CH3, CH2, and CH groups in the group 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 preferably compound III represented by ( ).

[0184] For compound III, the following compounds are preferred, for example. [ka] 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). Certain fluorine-free anionic surfactants are also preferably fluorine-free anionic surfactants having one or more carbonyl groups (excluding carbonyl groups in carboxyl groups) as described above, or 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. 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, it is also preferable that the fluorine-free anionic surfactant used is 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-based surfactant is used, an aqueous dispersion with a long coagulation completion time can be produced. In other words, the manufacturing method of the present disclosure is particularly suitable when the fluorine-free anionic surfactant is a carboxylic acid-type fluorine-free anionic surfactant. The above-mentioned carboxylic acid-type fluorine-free anionic surfactant is typically an anionic hydrocarbon surfactant having a hydrophilic portion of a carboxylate salt and a hydrophobic portion which is a long-chain hydrocarbon 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). Note that the ester group mentioned above 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 Anionic surfactants represented by (-LM)2, and the above formula:R 7z It is preferable that the anionic surfactant represented by (-LM)3 is at least one selected from the group consisting of those having a carboxyl group (-COOH) or a carboxyl group in which a hydrogen atom of the carboxyl group is substituted with an inorganic cation (e.g., a metal atom, ammonium, etc.), surfactant (1-0A), and those 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 its salts, 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 can 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. These stabilizing agents may be used individually or in combination of two or more. Paraffin wax is more preferred as a stabilizing agent. The 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 40-65°C, and more preferably 50-65°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 / deep thermometry (TG / DTA) system. 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 80-40 mol% of TFE units and 20-60 mol% of fluoroalkyl vinyl ether units.

[0205] (polymerization) In the manufacturing method of this disclosure, the polymerization reaction typically 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] (Fluoropolymer) As fluoromonomers, those having at least one double bond are preferred. Examples of the above fluoromonomers 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 side 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 ethers are, General formula (110): CF2=CF-ORf 111 (In the formula, Rf 111 represents a perfluoroorganic group. ) Fluoromers represented by ) General formula (120): CF2=CF-OCH2-Rf 121 (In the formula, Rf 121 Fluoromers represented by perfluoroalkyl groups having 1 to 5 carbon atoms, General formula (130): CF2=CFOCF2ORf 131 (In the formula, Rf 131 These are fluoromonomers represented by ( ), which are linear or branched perfluoroalkyl groups having 1 to 6 carbon atoms, cyclic perfluoroalkyl groups having 5 to 6 carbon atoms, or linear or branched perfluorooxyalkyl groups having 2 to 6 carbon atoms containing 1 to 3 oxygen atoms. General formula (140): CF2=CFO(CF2CF(Y 141 )O)m (CF2) n F (In the formula, 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 ), and General formula (150): CF2=CF-O-(CF2CFY 151 -O) n -(CFY 152 ) m -A 151 (In the formula, Y 151 Y represents a fluorine atom, a chlorine atom, a -SO2F group, or a perfluoroalkyl group. The perfluoroalkyl group may contain etheric oxygen and a -SO2F group. n represents an integer from 0 to 3. n Y 151 They may be the same or different. 152 represents a fluorine atom, a chlorine atom, or a -SO2F group. m represents an integer from 1 to 5. m Y 152 They may be the same or they may be different. 151 is, -SO2X 151 ,-COZ 151 or -POZ 152 Z 153 It represents X. 151 F, Cl, Br, I, -OR 151 or -NR 152 R 153 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 156 ) represents a fluoromonomer that may contain the same or different H, ammonium, alkali metal, fluorine atom, alkyl group, aryl group, or sulfonyl-containing group. It is preferable that it be at least one selected from the group consisting of the following:

[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, perfluoroethyl, perfluoropropyl, perfluorobutyl, perfluoropentyl, and perfluorohexyl groups. As a fluoromonomer represented by general formula (110), further, in the above general formula (110), Rf 111 Those in which the group is a perfluoro(alkoxyalkyl) group with 4 to 9 carbon atoms, Rf 111 The formula is as follows:

[0216] [ka]

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

[0218] CF3CF2CF2-(O-CF(CF3)-CF2) 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), General formula (160): CF2=CF-ORf 161 (In the formula, Rf 161represents a perfluoroalkyl group having 1 to 10 carbon atoms. Fluoromonomers represented by ) are preferred. Rf 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] The fluoromonomer represented by general formula (130) is preferably at least one selected from the group consisting of CF2=CFOCF2OCF3, CF2=CFOCF2OCF2CF3, and CF2=CFOCF2OCF2CF2OCF3.

[0223] The fluoromonomer represented by general formula (140) is preferably at least one selected from the group consisting of CF2=CFOCF2CF(CF3)O(CF2)3F, CF2=CFO(CF2CF(CF3)O)2(CF2)3F, and CF2=CFO(CF2CF(CF3)O)2(CF2)2F.

[0224] As the fluoromonomer represented by general formula (150), at least one selected from the group consisting of CF2=CFOCF2CF2SO2F, CF2=CFOCF2CF(CF3)OCF2CF2SO2F, CF2=CFOCF2CF(CF2CF2SO2F)OCF2CF2SO2F, and CF2=CFOCF2CF(SO2F)2 is preferred.

[0225] As a fluoromonomer represented by general formula (100), Rf 101 A fluoromonomer that is a straight-chain fluoroalkyl group is preferred, and Rf 101 A fluoromonomer in which the linear perfluoroalkyl group is is more preferred. 101 The carbon number of the compound is preferably 1 to 6. Examples of fluoromonomers represented by general formula (100) include CH2=CFCF3, CH2=CFCF2CF3, CH2=CFCF2CF2CF3, CH2=CFCF2CF2CF2H, CH2=CFCF2CF2CF2CF3, CHF=CHCF3 (E isomer), CHF=CHCF3 (Z isomer), and among these, 2,3,3,3-tetrafluoropropylene represented by CH2=CFCF3 is preferred.

[0226] As for fluoroalkylethylenes, General formula (170): CH2=CH-(CF2) n -X 171 (In the formula, X 171 is H or F, and n is an integer from 3 to 10. Fluoroalkylethylenes represented by ) are preferred, such as CH2=CH-C4F9 and CH2=CH-C6F 13 It is more preferable that it be at least one selected from the group consisting of the following:

[0227] Examples of the above fluoroalkylallyl ethers are, General formula (180): CF2=CF-CF2-ORf 111 (In the formula, 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 111As such, a perfluoroalkyl group having 1 to 10 carbon atoms or a perfluoroalkoxyalkyl group having 1 to 10 carbon atoms is preferred. As the fluoroalkyl allyl ether represented by general formula (180), at least one selected from the group consisting of CF2=CF-CF2-O-CF3, CF2=CF-CF2-O-C2F5, CF2=CF-CF2-O-C3F7, and CF2=CF-CF2-O-C4F9 is preferred, at least one selected from the group consisting of CF2=CF-CF2-O-C2F5, CF2=CF-CF2-O-C3F7, and CF2=CF-CF2-O-C4F9 is more preferred, and CF2=CF-CF2-O-CF2CF2CF3 is even more preferred.

[0229] The above fluorinated vinyl heterocyclic material is a general formula (230): [ka] (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 equation Y 232 or formula Y 233 That is the case.

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

[0231] The monomers that provide the crosslinking site are CF2=CFOCF2CF(CF3)OCF2CF2CN, CF2=CFOCF2CF(CF3)OCF2CF2COOH, CF2=CFOCF2CF(CF3)OCF2CF2CH2I, CF2=CFOCF2CF2CH2I, CH2=CFCF2OCF(CF3)CF2OCF(CF3)CN, CH2=CFCF2OCF(CF3)CF2OCF(CF3)COOH, CH2=CFCF2OCF( It is preferable that it is at least one selected from the group consisting of CF3)CF2OCF(CF3)CH2OH, CH2=CHCF2CF2I, CH2=CH(CF2)2CH=CH2, CH2=CH(CF2)6CH=CH2, and CF2=CFO(CF2)5CN, and more preferably at least one selected from the group consisting of CF2=CFOCF2CF(CF3)OCF2CF2CN and CF2=CFOCF2CF2CH2I.

[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, vinyl 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 monochloroacetic acid, vinyl adipate, vinyl acrylate, vinyl methacrylate, vinyl crotonate, vinyl sorbate, vinyl cinnamate, vinyl undecylenate, vinyl hydroxyacetate, and hydroxy 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) The above polymerization can yield an aqueous dispersion containing fluororesin. Fluororesin powder can be obtained by coagulating the fluororesin in the aqueous dispersion and drying it. 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, still more preferably 75% or more, and particularly preferably 80% or more. Among the fluororesins, fluororesins with a fluorine substitution rate of 90-100%, i.e., perfluororesins, are the most preferred.

[0240] (formula) Fluorine substitution rate (%) = (Number of fluorine atoms bonded to carbon atoms in the fluororesin) / ((Number of hydrogen atoms bonded to carbon atoms in the fluororesin) + (Number of fluorine and chlorine atoms bonded to carbon atoms in 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 high molecular weight PTFE core and a lower molecular weight PTFE or modified PTFE shell 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 monopolymer Shell: TFE monopolymer Core: Modified PTFE, Shell: TFE monopolymer Core: Modified PTFE Shell: Modified PTFE Core: TFE monopolymer; 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 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: CH2=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 This indicates the bond 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)ethylene; and perfluoroallyl ethers.

[0251] From the viewpoint of reactivity with TFE, the above-mentioned 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 in some cases the pH is adjusted to neutral or alkaline, and then the mixture is stirred more vigorously than during the reaction in a container 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 coating surfaces (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 disclosed herein can also be used to produce high molecular weight PTFE. In this disclosure, high molecular weight PTFE means PTFE that is non-melt processable. In one embodiment, high molecular weight PTFE has both 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 but does not fibrillate.

[0258] The above-mentioned non-meltability 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 TFE polymers. 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 ~7×10 5 The value 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 above high molecular weight PTFE preferably has a peak temperature of 333 to 347°C, and more preferably 335 to 345°C. The above low molecular weight PTFE preferably has a peak temperature of 322 to 333°C, and more preferably 324 to 332°C. The peak temperature can be identified as the temperature corresponding to the maximum value appearing in the heat of fusion curve obtained by heating PTFE that has no history of being heated to temperatures above 300°C at a rate of 10°C / min using a differential scanning calorimeter (DSC).

[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 lower, 346°C or lower, 345°C or lower, 344°C or lower, 343°C or lower, 342°C or lower, 341°C or lower, or 340°C or lower. 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 less, or 332°C or less. 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, 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 previously heated to temperatures above 300°C 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 PTFE is more preferably 55 mJ / mg or more, and even more preferably 58 mJ / mg or more.

[0267] The manufacturing method disclosed herein 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 can be polymerized with these monomers to obtain FEP. 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] The manufacturing method of this disclosure can also be used to produce TFE / perfluoro(alkyl vinyl ether) copolymer (PFA). 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 given by formula: CF2=CFORf 4 (In the formula, 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. Fluororesin Furthermore, this disclosure also relates to fluororesins that are substantially free of fluorine-containing surfactants, have an average primary particle size of 500 nm or less, have a color tone L* value greater than 60 for test specimens made from fluororesins in accordance with ASTM D4895-89, and have a carboxylic acid / CF2 peak intensity ratio of 0.0050 or more as measured by infrared spectroscopy.

[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] Fluoropolymers are characterized by a color tone L* value greater than 60 in a test specimen prepared from the fluoropolymer, in accordance with ASTM D4895-89. The color tone L* value of a test specimen prepared from the fluoropolymer 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 using the manufacturing method disclosed herein, the average primary particle size of fluororesin and low molecular weight PTFE can be adjusted to the above-mentioned range. This is presumed to be because the polymerization reaction proceeds with the fluororesin in an emulsified state in an aqueous medium. On the other hand, when fluororesin is produced by conventional suspension polymerization, it is difficult to generate primary particles of fluororesin, and 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 adjusted to 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 dynamic light scattering, for example, the ELSZ-1000S (manufactured by Otsuka Electronics Co., Ltd.) can be used.

[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 projected 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. Create a calibration curve. Using this calibration curve, the average particle diameter can be determined from the measured transmittance of 550 nm projected light for each sample.

[0279] In one embodiment, the carboxylic acid / CF2 peak intensity ratio of the fluororesin is 0.0050 or higher. In another embodiment, the fluororesin is low molecular weight PTFE, and the carboxylic acid / CF2 peak intensity ratio of the low molecular weight PTFE is 0.0050 or higher. The carboxylic acid / CF2 peak intensity ratio can be measured by infrared spectroscopy of the fluororesin.

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

[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 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 fluororesins of this disclosure or the low molecular weight PTFE of this disclosure. The forms of the fluororesins of this disclosure, the low molecular weight PTFE of this disclosure and the compositions of this disclosure are not particularly limited, but may be, for example, aqueous dispersions, coagulations, dried products, powders, pellets, 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 in addition to water, it may contain, for example, organic solvents such as alcohols, ethers, ketones, or paraffin waxes.

[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 90-100%.

[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 90-100%, i.e., perfluororesins, are most preferred.

[0293] (formula) Fluorine substitution rate (%) = (Number of fluorine atoms bonded to carbon atoms in the fluororesin) / ((Number of hydrogen atoms bonded to carbon atoms in the fluororesin) + (Number of fluorine and chlorine atoms bonded to carbon atoms in 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] One embodiment of the fluororesin, low molecular weight PTFE, and composition of the Disclosure substantially does not contain a fluorine-free surfactant. The fluororesin, low molecular weight PTFE, and composition substantially free of fluorine-free surfactants 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, even more preferably 1 ppb by mass or less, and particularly preferably, the amount of fluorine-free surfactants measured by liquid chromatography-mass spectrometry (LC / MS) is below the detection limit.

[0299] One embodiment of the fluororesin, low molecular weight PTFE, and composition of the present disclosure is substantially free of fluorine-containing surfactants.

[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 10 ppb by mass or less, and 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 using 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 resulting extract is then analyzed by LC / MS. To further improve extraction efficiency, treatments such as Soxhlet extraction or sonication may be performed. From the obtained LC / MS spectrum, molecular weight information is extracted and its agreement with the structural formula of the candidate surfactant is confirmed. Subsequently, aqueous solutions containing five or more levels of the identified surfactants were prepared, and LC / MS analysis was performed on each aqueous solution with its respective content. The relationship between the content and the area area corresponding to that content was then plotted, and a calibration curve was drawn. Then, using a calibration curve, the area of ​​the LC / MS chromatogram of the surfactant in the extract can be converted into the surfactant content.

[0302] Examples of the fluorine-containing surfactant include compounds represented by the following formulas. The fluorine-containing surfactant may be a mixture of these compounds. F(CF2)5COOM, CF3O(CF2)3OCHFCF2COOM, C3F7OCF(CF3)CF2OCF(CF3)COOM, CF3CF2CF2OCF(CF3)COOM, CF3CF2OCF2CF2OCF2COOM, C2F5OCF(CF3)CF2OCF(CF3)COOM, CF3OCF(CF3)CF2OCF(CF3)COOM, CF2ClCF2CF2OCF(CF3)CF2OCF2COOM, CF2ClCF2CF2OCF2CF(CF3)OCF2COOM, CF2ClCF(CF3)OCF(CF3)CF2OCF2COOM, CF2ClCF(CF3)OCF2CF(CF3)OCF2COOM, and, [ka] (In each formula, M is H, metal atom, NR 1 4. Imidazolium, pyridinium, or phosphonium, which may have substituents. 1 (This is either H or an organic group.)

[0303] One embodiment of the fluororesins, low molecular weight PTFEs, and compositions of the present disclosure substantially does not contain polymers (I) that include polymerization units (I) based on monomers (I) represented by general formula (I). Fluororesins, low molecular weight PTFEs, and compositions that substantially do not contain polymers (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, independently, F, Cl, H, or CF3; X 2 is H, F, alkyl group or fluorine-containing alkyl group; A 0 is an anionic group; R is a linking group; Z 1 and 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, even more preferably 1 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 fluororesins, low molecular weight PTFE, or compositions can be determined by solid-state NMR or fusion NMR. If polymer (I) contains carbonyl groups, it can also be determined by Fourier transform infrared spectroscopy. Also, International Publication Nos. 2014 / 099453, 2010 / 075497, 2010 / 075496, 2011 / 008381, 2009 / 055521, 1987 / 007619, Japanese Patent Publication No. 61-293476, 2010 / 075494, 2010 / 075359, 2012 / 082454, 2006 / 119224, 2013 / 085864, International Publication Nos. 2012 / 082707, 2012 / 082703, 2012 / 082451, 2006 / 135825, 2004 / 067588, 2009 / 068528, JP A 2004-075978, JP A 2001-226436, JP A 1992 / 017635, 2014 / 069165, and JP A H11-181009 describe the measurement methods for each polymer. The measurement methods for each polymer described in these publications can be used as methods for measuring the content of polymer (I).

[0306] The fluororesins, low molecular weight PTFEs, 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, (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 the substantially 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. A manufacturing method is provided. <2> According to the second aspect of this disclosure, A method for producing a fluoromonomer in the first polymerization, comprising at least tetrafluoroethylene, is provided according to a first aspect. <3> According to the third aspect of this disclosure, A manufacturing method is provided according to a first or second aspect, 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 the fourth aspect of this disclosure, A manufacturing method is provided that involves adding a polymerization initiator in the second polymerization step, according to any of the first to third aspects. <5> According to the fifth aspect of this disclosure, (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. A manufacturing method is provided. The ratio of radical generation (B / A) = B / A A: Radical generation rate 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 rate 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 fifth method for producing a fluoromonomer comprising at least tetrafluoroethylene is provided. <7> According to the seventh aspect of this disclosure, A manufacturing method according to a 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 producing the water-soluble fluoropolymer 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, according to any of the fifth to seventh aspects. <9> According to the ninth aspect of this disclosure, A manufacturing method is provided in which a polymerization initiator is further added in the second polymerization, according to any of the fifth to eighth aspects. <10> According to the tenth aspect of this disclosure, (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 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. From the start of the second polymerization, the second polymerization is carried out in the substantially 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. A manufacturing method is provided. <11> According to the eleventh aspect of this disclosure, A production method is provided in which the fluoromonomer in the first polymerization comprises at least tetrafluoroethylene, according to a tenth aspect. <12> According to the 12th aspect of this disclosure, A manufacturing method according to the tenth or eleventh aspect is provided, wherein the polymerization rate of the first polymerization is 3.0 g / (hr·L) or less. <13> According to the 13th aspect of this disclosure, A manufacturing method is provided that adds a polymerization initiator in the second polymerization, according to any of the 10th to 12th viewpoints. <14> According to the fourteenth aspect of this disclosure, 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. The peak intensity ratio of carboxylic acid / CF2 measured by infrared spectroscopy is 0.0050 or higher. A fluororesin is provided. <15> According to the 15th aspect of this disclosure, A fluororesin is provided that meets the 14th aspect, having a standard specific gravity of 2.230 or less. <16> According to the sixteenth aspect of this disclosure, A fluororesin according to the 14th or 15th aspect is provided, having a tensile strength of 15.0 N or more. <17> According to the seventeenth aspect of this disclosure, A fluororesin is provided that has a thermal decomposition rate of 0.030% or more at high temperatures and a Yellow Index value of -20 to 20, according to any of the 14th to 16th criteria. <18> According to the 18th aspect of this disclosure, A fluororesin is provided that has a thermal decomposition rate of 0.030% or more at high temperatures and a tensile strength of 15.0 N or more, according to any of the 14th to 17th views. <19> According to the 19th aspect of this disclosure, A fluororesin is provided that is substantially free of fluorine-containing surfactants according to any of the 14th to 18th views. <20> According to the 20th aspect of this disclosure, A fluororesin is provided that does not contain a polymer (I) containing a polymerization unit (I) based substantially on a monomer (I) represented by general formula (I). General formula (I):CX1 X 3 =CX 2 R(-CZ 1 Z 2 -A 0 ) m (In the formula, X 1 and X 3 These are, independently, F, Cl, H, or CF3; X 2 is H, F, alkyl group or fluorine-containing alkyl group; A 0 is an anionic group; R is a linking group; Z 1 and 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. <21> According to the 21st aspect of this disclosure, It contains virtually no fluorine-containing surfactants. The average primary particle diameter is 500 nm or less. The color 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 is provided. <22> According to the 22nd aspect of this disclosure, A low molecular weight polytetrafluoroethylene is provided, according to a 21st viewpoint, in which the carboxylic acid / CF2 peak intensity ratio measured by infrared spectroscopy is 0.0050 or higher. [Examples]

[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> One g of aqueous dispersion was dried in a forced-air dryer at 150°C for 60 minutes, and the percentage of the mass of the residual material after heating relative to the mass of the aqueous dispersion (1 g) was used.

[0312] <Average primary particle diameter> A aqueous dispersion was diluted with water until the solid content concentration reached 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 diameter determined by measuring the directional diameter using transmission electron microscopy. Using this calibration curve, the average primary particle diameter 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 measurements were performed using the water displacement method in accordance with ASTM D-792.

[0314] <Melting point (peak temperature) 1> For the water-soluble polymers obtained in the examples, a differential thermogravimetric (TG / DTA) thermogravimetric analyzer was used to heat an aluminum pan in an atmospheric environment from 25°C to 600°C at a rate of 10°C / min, until the temperature corresponding to the maximum value of the differential thermal (DTA) curve was reached.

[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 at which the endothermic peak in the heat of fusion curve reached its maximum value 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 examples, a differential scanning calorimeter (DSC) was used to plot a heat of fusion curve at 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 melting point of PTFE.

[0317] <Rate of thermal decomposition at high temperatures> Approximately 10g of PTFE powder was placed in an aluminum cup (capacity 50ml, top diameter 61mm, bottom diameter 42mm, depth 33mm), and held for 2 hours in a hot air circulating electric furnace preheated to a heating temperature of 370±2℃. The weight was then measured, and the thermal decomposition rate at high temperatures was determined using the following formula. High-temperature thermal decomposition rate (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 ASTM E313.

[0319] <Carboxylic acid / CF2 peak intensity ratio> A fluoropolymer powder was pre-formed using a hand press to create a film with a thickness of approximately 0.1 mm. The fabricated film was subjected to infrared absorption spectroscopy, and the CF2 peak intensity (absorption frequency 1200) was calculated by dividing the peak intensity of the carboxylic acid group (absorption frequency 3560) by the peak intensity of CF2.

[0320] <Measurement of extrusion pressure> 100 g of PTFE powder is mixed with 21.7 g of lubricant (product name: Isopar H (trademark registered), manufactured by Exxon) in a glass bottle at room temperature for 3 minutes. The glass bottle is then left at room temperature (25°C) for at least 1 hour before extrusion to obtain the lubricated resin. The lubricated 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 product). The extrusion speed, i.e., the ram speed, is set to 20 inches / min (51 cm / min). The extrusion pressure is measured when the extrusion load reaches equilibrium during paste extrusion and divided by the cross-sectional area of ​​the cylinder used for paste extrusion.

[0321] <Extension 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 a suitable length, and each end is secured to clamps 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 elongation, 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] <Stretching strength> The stretched bead (created by stretching the bead) obtained in the above stretch test 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. The strength at which it breaks is measured as the stretch strength.

[0323] <Stress relaxation time> The ends of the stretched bead obtained in the stretching test described above are connected to a fastener to create a taut bead sample with a total length of 8 inches (20 cm). The oven is kept at 390°C, and the fastener is inserted into the oven through a (covered) slit on the side of the oven. The time required from the moment of insertion into the oven until the bead sample breaks is measured 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 was held at 200°C for 30 hours and measured using a color meter ZE6000 manufactured by Nippon Denshoku Industries, Ltd., in accordance with the measurement method compliant with JIS Z 8781-4:2013.

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

[0326] Two hours after the addition of APS, the pressure inside the reactor reached 0.75 MPaG. The reactor temperature was changed to 70°C, and the contents of the reactor were aspirated while simultaneously purging 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 reactor pressure was increased to 0.83 MPaG using 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 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, and the separated paraffin was removed to obtain an aqueous PTFE dispersion. 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 aqueous PTFE dispersion had a solid content concentration of 18.8% by mass and an average primary particle size of 210 nm. The obtained aqueous PTFE 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 as determined by DSC, indicating it was high molecular weight PTFE. The carboxylic acid / CF2 peak intensity ratio was 0.019, the thermal decomposition rate at high temperatures was 0.282%, and the color L* value of the sample molded according to ASTM D4895-89 was 92.1, with a yellow index value of -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 27.5 g of paraffin and 520 g of deionized water were placed in a 1 L glass reactor equipped with a stirrer, and the reactor was sealed. The reactor was then heated to 90°C while simultaneously being purged with TFE to remove oxygen, and stirred at a speed of 540 rpm. 0.17 g of propane was added to the reactor as a chain transfer agent and injected under pressure with TFE until the pressure reached 0.78 MPaG. The reactor temperature was maintained 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 reactor pressure was increased to 0.83 MPaG using TFE.

[0332] Two hours after the addition of 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 while simultaneously purging 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 reactor pressure was increased to 0.83 MPaG using 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 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 aqueous PTFE dispersion had a solid content concentration of 21.1% by mass and an average primary particle size of 199 nm. The obtained aqueous PTFE 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 as determined by DSC, indicating it was high molecular weight PTFE. The carboxylic acid / CF2 peak intensity ratio was 0.020, the thermal decomposition rate at high temperatures was 0.235%, and the color L* value of the sample molded according to ASTM D4895-89 was 86.7, with a yellow index value of -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 In a 6L stainless steel reactor equipped with a stirrer, 180g of paraffin, 0.011g of 2-propanol as a chain transfer agent, 0.0021g of A1315 (Harcros Chemicals, average molecular weight 860) as a nucleating agent, and 3500g of deionized water were charged and sealed. The reactor was then heated to 90°C while simultaneously being suctioned and purged with TFE to remove oxygen from the reactor, and stirred at a speed of 260 rpm. 3.0g of HFP was charged into the reactor and injected under pressure with TFE until the pressure reached 0.78 MPaG. The reactor temperature was maintained at 90°C, and after changing the stirring speed to 70 rpm, 0.36g of APS dissolved in 10g of deionized water was added, and the reactor pressure was increased to 0.83 MPaG using TFE. One hour after the addition of APS, the pressure inside the reactor was 0.79 MPaG. 0.011g of 2-propanol, 0.0021g of A1315, and 0.358g 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 reached 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 temperature 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 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 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 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, and the separated paraffin was removed to obtain an aqueous PTFE dispersion. No polymer adhesion to the reactor was observed.

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

[0341] The obtained aqueous PTFE 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 as determined by DSC, indicating it was high molecular weight PTFE. The carboxylic acid / CF2 peak intensity ratio was 0.010, the thermal decomposition rate at high temperatures was 0.194%, and the color L* value of the sample molded according to ASTM D4895-89 was 86.5, with a yellow index value of 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 In a 6L stainless steel reactor equipped with a stirrer, 180g of paraffin, 0.011g of 2-propanol as a chain transfer agent, 0.0021g of A1315 as a nucleating agent, and 3500g of deionized water were charged and sealed. The reactor was then heated to 90°C while simultaneously being purged with TFE to remove oxygen from the reactor, and stirred at a speed of 260 rpm. 3.0g of HFP was charged into the reactor and injected with TFE until the pressure reached 0.78 MPaG. The reactor temperature was maintained at 90°C, the stirring speed was changed to 70 rpm, and then 0.36g of APS dissolved in 10g of deionized water was added, and the reactor pressure was increased to 0.83 MPaG using 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 simultaneously 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 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 0.16 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 adhesion to the reactor was observed.

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

[0348] The obtained aqueous PTFE 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 as determined by DSC, indicating it was high molecular weight PTFE. The carboxylic acid / CF2 peak intensity ratio was 0.019, the thermal decomposition rate at high temperatures was 0.051%, and the color L* value of the sample molded according to ASTM D4895-89 was 90.6, with a yellow index value of -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 In a 6L stainless steel reactor equipped with a stirrer, 180g of paraffin, 0.011g of 2-propanol as a chain transfer agent, 0.0021g of A1315 as a nucleating agent, and 3500g of deionized water were charged and sealed. The reactor was then heated to 90°C while simultaneously being purged with TFE to remove oxygen from the reactor, and stirred at a speed of 260 rpm. 3.0g of HFP was charged into the reactor and injected with TFE until the pressure reached 0.78 MPaG. The reactor temperature was maintained at 90°C, the stirring speed was changed to 70 rpm, and then 0.36g of APS dissolved in 10g of deionized water was added, and the reactor pressure was increased to 0.83 MPaG using 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 simultaneously 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 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 adhesion to the reactor was observed.

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

[0355] The obtained aqueous PTFE 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 as determined by DSC, indicating it was high molecular weight PTFE. The carboxylic acid / CF2 peak intensity ratio was 0.017, the thermal decomposition rate at high temperatures was 0.034%, and the color L* value of the sample molded according to ASTM D4895-89 was 90.2, with a yellow index value of -11.7.

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

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

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

[0362] The obtained aqueous PTFE 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 standard specific gravity of the obtained PTFE powder was 2.188, and the peak temperature determined by DSC was 337°C, indicating that it was high molecular weight PTFE. The carboxylic acid / CF2 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, with a yellow index value of -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 tensile strength was 25.6 N, and the stress relaxation time was 166 seconds.

[0365] Example 7 In a 6L stainless steel reactor equipped with a stirrer, 96g of paraffin, 0.00165g of Pronon #104 (manufactured by NOF Corporation, average molecular weight 1670), a fluorine-free nonionic surfactant, and 3280g of deionized water were charged as nucleating agents, and the reactor was sealed. Then, the reactor was heated to 90°C while simultaneously being suctioned and purged with TFE to remove oxygen from the reactor, and stirred at a speed of 250 rpm. 3.0g of HFP was charged into the reactor and injected under pressure with TFE until the pressure reached 0.78 MPaG. The reactor temperature was maintained at 90°C, and after changing the stirring speed to 90 rpm, 0.33g of ammonium persulfate (APS) dissolved in 10g of deionized water was added, and the reactor pressure was increased to 0.83 MPaG using 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 0.33 g of APS dissolved in 20 g of deionized water was added, and the reactor pressure 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, and the separated paraffin was removed to obtain an aqueous PTFE dispersion. No polymer adhesion to the reactor was observed.

[0368] The obtained aqueous PTFE dispersion had a solid content concentration of 16.2% by mass and an average primary particle size of 193 nm. The obtained aqueous PTFE 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 was found to be low molecular weight PTFE, with a peak temperature of 328°C and a melt viscosity of 22800 Pa·s, as determined by DSC. The peak intensity ratio of carboxylic acid / CF2 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 In a 1L glass reactor equipped with a stirrer, 27.5g of paraffin, 0.00033g of Pronon #104 (manufactured by NOF Corporation, average molecular weight 1670), a fluorine-free nonionic surfactant, and 520g of deionized water were charged as nucleating agents, and the reactor was sealed. The reactor was then heated to 90°C while simultaneously being suctioned and purged with a TFE to remove oxygen, and stirred at a speed of 550 rpm. 0.5g of HFP was charged into the reactor and injected under pressure with a TFE until the pressure reached 0.78 MPaG. The reactor temperature was maintained at 90°C, and 0.11g of ammonium persulfate (APS) dissolved in 10g of deionized water was added, and the reactor pressure was increased to 0.83 MPaG using a TFE.

[0372] After APS was added, a pressure drop was observed, and TFE was then 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 180g of paraffin, 6.4g of formic acid as a nucleating agent, and 3500g of deionized water were charged into a 6L volume stainless steel reactor and sealed. The reactor was then heated to 85°C while simultaneously being purged with TFE to remove oxygen from the reactor, and stirred at a speed of 260 rpm. The reactor was then injected with 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 0.36g of APS dissolved in 10g of deionized water was added, and the reactor pressure was increased to 0.83 MPaG using TFE.

[0374] Three hours after adding APS, the pressure inside the reactor reached 0.76 MPaG. The reactor temperature was changed to 70°C, and the contents of the reactor were aspirated while simultaneously purging 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 reactor pressure was increased to 0.83 MPaG using 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 aqueous PTFE dispersion had a solid content concentration of 20.1% by mass and an average primary particle size of 202 nm.

[0377] The obtained aqueous PTFE 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 as determined by DSC, indicating that it was high molecular weight PTFE. The carboxylic acid / CF2 peak intensity ratio was 0.010, the thermal decomposition rate at high temperatures was 0.199%, and the color L* value of the sample molded according to ASTM D4895-89 was 89.3, with a yellow index value of -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 liquid A by the first polymerization> 3309g of deionized water was placed in a 6.0L stainless steel pressure-resistant reaction vessel. The reactor was sealed and heated to 70°C while simultaneously being purged with TFE to remove oxygen from the reactor, and the contents were stirred. Then, 245.0g of perfluoro(methyl vinyl ether) (PMVE) was placed in the vessel. The temperature was raised to 90°C while stirring at 70 rpm, 32.4g of TFE was placed in the vessel, and the pressure was increased to 1.65 MPa. Next, 0.83g of ammonium persulfate (APS), dissolved in 10g 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 placed in the vessel was 8g. 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 liquid B> 127 g of AmberLite HPR650H (DuPont, cation exchange resin) was added to 3100 g of raw material solution A. After 60 minutes of 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. After 60 minutes of 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> 1158g of deionized water, 2442g of raw material solution B, and 180g of paraffin wax were charged into a 6.0L stainless steel pressure reactor. The reactor was sealed and heated to 70°C while simultaneously being purged with TFE to remove oxygen from the reactor, and the contents were stirred at 160 rpm. 0.205g of disuccinate oxide (DSAP) dissolved in 10g 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 900g, 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, and the separated paraffin was removed to obtain a PTFE aqueous dispersion (A).

[0383] The obtained aqueous PTFE dispersion (A) had a solid content concentration of 20.0% by mass and an average primary particle size of 202 nm. The obtained aqueous PTFE 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 as determined by DSC, indicating it was high molecular weight PTFE. The carboxylic acid / CF2 peak intensity ratio was 0.006, the thermal decomposition rate at high temperatures was 0.44%, and the color L* value of the sample molded according to ASTM D4895-89 was 88.1, with a yellow index value of 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. (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.

2. The manufacturing method according to claim 1, wherein the fluoromonomer in the first polymerization comprises at least tetrafluoroethylene.

3. 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.

4. The manufacturing method according to claim 1 or 2, wherein a polymerization initiator is added in the second polymerization.

5. (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))

6. The manufacturing method according to claim 5, wherein the fluoromonomer comprises at least tetrafluoroethylene.

7. 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.

8. The manufacturing method according to claim 5 or 6, 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. The manufacturing method according to claim 5 or 6, wherein a polymerization initiator is further added in the second polymerization.

10. (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 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. 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.

11. The manufacturing method according to claim 10, wherein the fluoromonomer in the first polymerization comprises at least tetrafluoroethylene.

12. 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.

13. The manufacturing method according to claim 10 or 11, wherein a polymerization initiator is added in the second polymerization.

14. 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.

15. The fluororesin according to claim 14, wherein the standard specific gravity is 2.230 or less.

16. The fluororesin according to claim 14 or 15, wherein the tensile strength is 15.0 N or more.

17. The fluororesin according to claim 14 or 15, wherein the thermal decomposition rate at high temperatures is 0.030% or more, and the yellow index value is -20 to 20.

18. The fluororesin according to claim 14 or 15, wherein the thermal decomposition rate at high temperatures is 0.030% or more, and the tensile strength is 15.0 N or more.

19. A fluororesin according to claim 14 or 15 that is substantially free of fluorine-containing surfactants.

20. The fluororesin according to claim 14 or 15, 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 fluorinated 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 fluorinated alkyl group; m is an integer of 1 or more.)

21. 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.

22. 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