Fluorine-containing resin composition and method for producing same

Abstract

Provided is a fluorine-containing resin composition that can be used as a coating material. A fluorine-containing resin composition contains 95 mass% or more of a fluorine-containing copolymer (A) containing a monomer having a functional group as a constituent unit, and 100-3,000 ppm of water (B), as constituent components.

Description

Fluorine-containing resin composition and method for producing the same

[0001] This disclosure relates to a fluororesin composition and a method for producing the same.

[0002] Paints containing fluororesins are used in many fields because they have excellent properties such as weather resistance, stain resistance, corrosion resistance, chemical resistance, solvent resistance, and heat resistance. In terms of distribution, fluororesins are being considered in solid form, and are mixed with a solvent during the paint-making process.

[0003] The advantages of distributing fluororesins in a solid state include lower costs in distribution and storage due to their smaller volume, and the ability to appropriately select and use solvents according to the application, substrate, and regulations.

[0004] Patent documents 1 to 3 disclose that, for this purpose, a fluororesin-containing organic solvent solution is dried to remove the solvent.

[0005] Japanese Patent Publication No. 08-118357, Japanese Patent Publication No. 2005-298690, Japanese Patent Publication No. 2006-2136

[0006] The purpose of this disclosure is to provide a fluororesin composition that can be used as a paint.

[0007] This disclosure relates to a fluorine-containing resin composition characterized by containing 95% by mass or more of a fluorine-containing copolymer (A) containing monomers having functional groups as constituent units, and 100 to 3000 ppm of water (B) as constituent components.

[0008] The above fluorine-containing resin composition preferably further contains 0.1 to 2% by mass of an organic solvent (C). The above fluorine-containing polymer (A) preferably contains monomers having hydroxyl groups as constituent units, and the hydroxyl value of the fluorine-containing copolymer is preferably 45 mg KOH / g or more. The above fluorine-containing copolymer (A) preferably is a fluorine-containing copolymer that contains a fluoroolefin unit and at least one monomer unit selected from the group consisting of vinyl esters, vinyl ethers, (meth)acrylic esters and allyl ethers.

[0009] The above-mentioned fluorine-containing copolymer (A) contains monomers having an acid value as constituent units, and it is preferable that the acid value of the above-mentioned fluorine-containing copolymer (A) is 1.0 mg KOH / g or more. It is preferable that the above-mentioned fluorine-containing copolymer (A) has a weight-average molecular weight (Mw) on a polystyrene basis measured by GPC of 50,000 or less.

[0010] The above-mentioned fluorine-containing copolymer (A) is preferably soluble in parachlorobenzotrifluoride, and its rotational viscosity at 25°C, measured with a B-type viscometer when dissolved in parachlorobenzotrifluoride to a solid content concentration of 50% by mass, is preferably 10,000 mPa·s or less.

[0011] The organic solvent (C) preferably contains at least one selected from the group consisting of n-butyl acetate, ethyl acetate, xylene, toluene, methyl ethyl ketone, methyl isobutyl ketone, acetone, and alcohols having 4 or fewer carbon atoms.

[0012] The fluorine-containing paint composition of this disclosure is preferably in flake, powder, or pellet form at a temperature of 25°C. In the case of pellet form, it is preferable that the pellet form has an average major diameter of 20 mm or less and an average aspect ratio of 2 or less. The fluorine-containing paint composition of this disclosure contains the above-mentioned fluorine-containing copolymer (A) at a content of 99.0 to 99.9% by mass, contains the above-mentioned water (B) at a content of 100 to 3000 ppm, and contains the organic solvent (C) at a content of 0.1 to 1.0% by mass. The above-mentioned fluorine-containing copolymer (A) preferably contains fluoroolefin units, at least one monomer unit selected from the group consisting of vinyl monomers having hydroxyl groups and vinyl monomers having carboxyl groups, and at least one monomer unit selected from the group consisting of alkyl vinyl esters and alkyl vinyl ethers.

[0013] The present disclosure also relates to a method for producing a fluororesin composition (A) according to claim 1 or 2, characterized by the step of desolventing a fluororesin solution obtained by dissolving the fluororesin in an organic solvent (C) at a heat transfer medium temperature of 150°C or lower until the organic solvent (C) is reduced to 2% by mass or less, and then removing water so that the water content is 100 to 3000 ppm.

[0014] The present disclosure relates to a fluororesin composition in which the solvent used during polymerization is sufficiently removed and the water content is further reduced, as well as a method for producing the same.

[0015] The present disclosure will be described in detail below. In this disclosure, "units derived from monomers" may be simply referred to as "monomer units." This disclosure relates to a fluorine-containing resin composition in which the water content has been reduced to a predetermined range. For the purposes described above, it is known that a fluorine-containing copolymer is dried in an organic solvent solution in order to obtain a solvent-free solid fluorine-containing copolymer.

[0016] However, when such a fluororesin composition is dissolved in a solvent and used as a paint, if water remains in the composition, this remaining water may degrade the performance of the paint.

[0017] Specifically, if water remains, in the case of a hardening paint, the hardener and water may react, which can reduce the crosslinking density of the paint film.

[0018] To mitigate these problems, it is desirable to thoroughly remove water. However, if the heating time is extended to remove the solvent, the resin may become more molecular weight, which is problematic for resins that are prone to becoming more molecular weight when heated. Blocking problems also tend to occur.

[0019] Furthermore, it may be necessary to form the fluororesin composition into pellet or flake shapes. Pellet-shaped resin compositions have the advantage of a large surface area and good solvent solubility. Flake-shaped resin compositions have the advantage of a small contact area and excellent blocking resistance. However, in order to form pellets or flakes, it is desirable to melt the dried resin, rapidly cool it, and then cut it.

[0020] In this process, it is necessary to rapidly cool the molten resin. However, rapid cooling of the resin has the problem of easily increasing its water content. This problem is particularly important when the resin has functional groups that have a high affinity for water.

[0021] From the above perspective, reducing the water content is important. The fluororesin composition of this disclosure is characterized in that the amount of water it contains is within a specific range.

[0022] (Moisture Content) The fluororesin composition of this disclosure has a moisture content (water (B) content in the fluororesin composition) within the range of 100 to 3000 ppm. This moisture content is a value measured by the Karl Fischer method. The upper limit of the moisture content is preferably 3000 ppm or less, and more preferably 2000 ppm or less. While a lower moisture content is preferable, achieving a moisture content of 100 ppm or less would require heating at 30°C or higher, which may cause resin blocking. Therefore, the above range is preferable because it eliminates the need for such heating to remove moisture.

[0023] (Fluorine-containing copolymer (A)) The composition of the present disclosure contains a fluorine-containing copolymer (A) which contains monomers having functional groups as constituent units. The fluorine-containing copolymer (A) has excellent properties such as weather resistance and solvent resistance, and the present disclosure relates to a composition that can exhibit the properties of such a fluorine-containing copolymer.

[0024] The above-mentioned fluorine-containing copolymer (A) has structural units (b1) derived from fluoroolefins (hereinafter sometimes referred to as "fluoroolefin units"). Fluoroolefin units (b1) refer to structures derived from unsaturated compounds containing fluorine atoms. Specifically, examples include tetrafluoroethylene, chlorotrifluoroethylene, trifluoroethylene, vinylidene fluoride, hexafluoropropylene, and pentafluoropropylene, which can be appropriately selected depending on the properties required for the coating film and the combination with copolymer components. Furthermore, one or more of these fluoroolefins can be used. Among these, it is preferable to use at least one (for example, one or two) selected from structural units derived from tetrafluoroethylene and chlorotrifluoroethylene, and in particular, structural units derived from tetrafluoroethylene are preferred.

[0025] The above-mentioned fluorine-containing copolymer (A) contains monomers having functional groups as constituent units. The above-mentioned functional groups are not particularly limited and may include monomers having hydroxyl groups, carboxyl groups, amide groups, amino groups, mercapto groups, glycidyl groups, or isocyanate groups, hydrolyzable silyl groups, etc. When the functional group is used as a curable composition, it is preferable that it acts as a curing functional group, with hydroxyl groups being the most preferred. When the fluorine-containing resin composition of this disclosure is used in a paint, it is preferable that such a functional group acts as a reactive functional group that reacts with the curing agent.

[0026] Examples of monomers having functional groups include vinyl monomers having functional groups, and more specifically, the following can be listed: Monomers having hydroxyl groups (hydroxyl group-containing monomers) include hydroxyalkyl vinyl ethers such as hydroxyethyl vinyl ether, hydroxypropyl vinyl ether, hydroxybutyl vinyl ether, hydroxyisobutyl vinyl ether, and hydroxycyclohexyl vinyl ether; esters of hydroxyalkyl carboxylic acids and vinyl alcohols such as vinyl hydroxyacetate, vinyl hydroxypropioate, vinyl hydroxybutyrate, vinyl hydroxyvalerate, vinyl hydroxyisobutyrate, and vinyl hydroxycyclohexanecarboxylate; hydroxyalkyl allyl ethers such as hydroxyethyl allyl ether, hydroxypropyl allyl ether, hydroxybutyl allyl ether, hydroxyisobutyl allyl ether, and hydroxycyclohexyl allyl ether; Examples include hydroxyalkyl allyl esters such as hydroxyethyl allyl ester, hydroxypropyl allyl ester, hydroxybutyl allyl ester, hydroxyisobutyl allyl ester, and hydroxycyclohexyl allyl ester; hydroxyalkyl esters of acrylic acid or methacrylic acid such as 2-hydroxyethyl acrylate, hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, and hydroxypropyl methacrylate; unsaturated alcohols such as 3-methyl-3-buten-1-ol (isoprenol), 3-methyl-2-buten-1-ol, 2-methyl-3-buten-2-ol, 2-methyl-2-buten-1-ol, and 2-methyl-3-buten-1-ol; and one or more of these partially fluorine-substituted compounds. Examples of monomers having a carboxyl group include crotonic acid, undecylenic acid, (meth)acrylic acid, and carboxylalkyl allyl ethers. Examples of monomers having an amide group include (meth)acrylamide and N-methylolacrylamide. Examples of monomers having an amino group include aminoalkyl vinyl ethers and aminoalkyl allyl ethers.Examples of monomers having a glycidyl group include glycidyl (meth)acrylate, glycidyl vinyl ether, and glycidyl allyl ether. Examples of monomers having an isocyanate group include vinyl isocyanate and isocyanate ethyl acrylate. Among these, hydroxyalkyl vinyl ethers, unsaturated alcohols, and carboxyalkyl allyl ethers are preferred, and among these, 4-hydroxybutyl vinyl ether, 2-hydroxyethyl vinyl ether, isoprenol, crotonic acid, and undecylenic acid are preferred.

[0027] The above-mentioned fluorine-containing copolymer (A) preferably contains monomers having the above-mentioned functional group in a proportion of 1 to 50 mol%. The lower limit is more preferably 5 mol%. The upper limit is even more preferably 40 mol%.

[0028] The fluorine-containing copolymer (A) described above preferably has a hydroxyl value of 45 mg KOH / g or more. This range is preferable because, when used in a curable paint, it provides sufficient crosslinking reaction sites, allowing for good coating film properties even when the molecular weight of the polymer is reduced. The hydroxyl value can be adjusted to a predetermined value by controlling the proportion of hydroxyl group-containing monomers used. The hydroxyl value is more preferably 50 mg KOH / g or more, and even more preferably 56 mg KOH / g or more. The upper limit of the hydroxyl value is not particularly limited, but for example, it can be 150 mg KOH / g or less.

[0029] The fluorine-containing copolymer (A) preferably further contains at least one monomer unit (for example, one, two, three, or four) selected from the group consisting of vinyl esters, vinyl ethers, (meth)acrylic esters, and allyl ethers. Such monomers are preferable because they can lower the melting point and softening point of the fluorine-containing copolymer and further improve paintability, thereby imparting appropriate physical properties to the coating film, such as hardness, flexibility, gloss, solvent solubility, curing agent compatibility, and adhesion.

[0030] Examples of materials that can be used as the vinyl esters, vinyl ethers, (meth)acrylic esters, and allyl ethers mentioned above are given below. Examples of vinyl ethers include alkyl vinyl ethers, more specifically ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, isobutyl vinyl ether, cyclohexyl vinyl ether, etc. The alkyl group of alkyl vinyl ether may be linear or cyclic. Examples of vinyl esters include alkyl vinyl esters (esters of alkyl carboxylic acid and vinyl alcohol), more specifically vinyl neononanoate, vinyl versatate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl valerate, vinyl cyclohexanecarboxylate, vinyl benzoate, p-t-butylbenzoate, etc. The alkyl group of alkyl vinyl ester may be linear or cyclic. Examples of the above (meth)acrylic esters include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, (iso)butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. Examples of the above allyl ethers include alkyl allyl ethers, more specifically, ethyl allyl ether, propyl allyl ether, butyl allyl ether, isobutyl allyl ether, and cyclohexyl allyl ether. The alkyl group of the alkyl allyl ether may be linear or cyclic.

[0031] Furthermore, in addition to the monomers mentioned above, the constituent units may also be based on monomers having a carboxyl group. Examples of monomers having a carboxyl group include α,β-unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, succinic acid, succinic anhydride, fumaric acid, fumaric anhydride, crotonic acid, maleic acid, and maleic anhydride, as well as fluorine-substituted monomers such as perfluorobutenoic acid.

[0032] The above-mentioned fluorine-containing copolymer (A), when it contains structural units based on monomers having an acid value (for example, monomers having a carboxyl group), preferably has an acid value of 1.0 mg KOH / g or more. Having such an acid value is desirable in terms of improving the dispersibility of pigments and the stability of paints. The above acid value can be set to a predetermined value by adjusting the proportion of monomers having a carboxyl group used. The above acid value is more preferably 1.5 mg KOH / g or more, and even more preferably 2.0 mg KOH / g or more. The upper limit of the above acid value is not particularly limited, but from the viewpoint of water resistance, weather resistance, and thermal stability, it can be, for example, 30 mg KOH / g or less. When it contains structural units based on monomers having a carboxyl group, the content of structural units based on monomers having a carboxyl group is preferably 0.1 mol% or more, and more preferably 0.5 mol% or more, relative to the total amount of structural units constituting the fluorine-containing copolymer (A). Furthermore, the content of constituent units based on monomers having carboxyl groups is preferably 10 mol% or less, and more preferably 5 mol% or less, relative to the total amount of structural units constituting the fluorine-containing copolymer (A). In terms of suppressing high molecular weight formation, it is preferable that the content of constituent units based on monomers having carboxyl groups is within the above range.

[0033] The fluorine-containing copolymer (A) described above may have constituent units derived from monomers other than those described above, to the extent that it does not impair the purpose of this disclosure.

[0034] Examples of constituent units derived from monomers other than those mentioned above include non-fluorinated olefins, acrylic esters, and allyl ethers. Examples of non-fluorinated olefins include ethylene, propylene, n-butene, and isobutene. Examples of acrylic esters include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, (iso)butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. Examples of allyl ethers include ethyl allyl ether, propyl allyl ether, butyl allyl ether, isobutyl allyl ether, and cyclohexyl allyl ether. One or more of these may be used.

[0035] When copolymerizing the above-mentioned non-fluorinated olefin, its content is preferably 0 to 50 mol% of the total fluorine-containing copolymer. The upper limit is preferably less than 45 mol%, and more preferably 40 mol% or less.

[0036] When copolymerizing the above-mentioned acrylic esters or allyl ether esters, their content is preferably 0 to 5 mol% of the total fluorine-containing copolymer.

[0037] In the above-mentioned fluorine-containing copolymer (A), the fluoroolefin units are preferably 10 to 60 mol% of the total polymerization units constituting the polymer. By keeping the amount within this range, a composition with excellent weather resistance and solvent resistance can be obtained. The lower limit of the above blending amount is more preferably 25 mol%, and even more preferably 35 mol%. The upper limit of the above blending amount is more preferably 50% by mass.

[0038] In the above fluorine-containing copolymer (A), the structural unit (b2) derived from at least one selected from the group consisting of vinyl esters, vinyl ethers, allyl ethers, and hydroxyl group-containing unsaturated compounds (for example, 1, 2, 3, or 4 kinds) is preferably 40 to 90 mol% of the total polymerization units constituting the polymer. By setting it within such a range, a composition excellent in solubility in a solvent and further excellent in pigment dispersibility can be obtained. The lower limit of the above blending amount is more preferably 45 mol%, and still more preferably 50 mol%. The upper limit of the above blending amount is more preferably 75 mol%, and still more preferably 65 mol%.

[0039] The above fluorine-containing copolymer preferably has a polystyrene-reduced weight average molecular weight (Mw) measured by GPC of 50,000 or less. By setting it within such a range, it is preferable in terms of excellent solubility in a solvent and achieving high solid content. Here, the weight average molecular weight is a value measured by the measurement method described in the examples.

[0040] The above weight average molecular weight is more preferably 45,000 or less, and still more preferably 40,000 or less. The lower limit of the above weight average molecular weight is not particularly limited, but for example, it is preferably 5,000 from the viewpoints of weather resistance and flexibility.

[0041] The fluorine-containing resin composition of the present disclosure contains 95% by mass or more of the fluorine-containing copolymer (A). That is, it is basically composed of the fluorine-containing copolymer (A), satisfies the above-mentioned predetermined solvent amount and water amount, and may not contain other components.

[0042] Examples of other components include impurities during the polymerization of the fluorine-containing copolymer (A). When impurities are contained, for example, cases where polymerization catalyst residues, unreacted monomers, raw material impurity residues, etc. remain may be considered. The amount of the fluorine-containing copolymer (A) in the fluorine-containing resin composition is a value measured by the weight residue when 2 g of the resin is dried in an electric furnace at 150°C for 1 hour. The content is more preferably 97% by mass or more, still more preferably 98% by mass or more, and even more preferably 99.0% by mass or more. Since water (B) and the organic solvent (C) are sufficiently removed, the higher the amount of the fluorine-containing copolymer (A) in the fluorine-containing resin composition, the better. However, for example, it is 99.9% by mass or less.

[0043] (Organic solvent (C)) In the fluorine-containing resin composition of the present disclosure, the content of the organic solvent is preferably 0.1 to 2% by mass. When the content of the organic solvent is 2% by mass, it is preferable in terms of suppressing the generation of odor, the decrease in the blocking property of the resin, the inability to maintain the shape due to plasticization, and the difficulty in dissolution in the solvent during use. The content of the organic solvent is more preferably 1.0% by mass or less. Although the smaller the amount of the organic solvent, the better, in order to make it 0.1% by mass or less, it is necessary to increase the temperature during desolvation, which may cause an increase in the polymer molecular weight or discoloration of the resin due to excessive heat applied to the resin. Therefore, it is preferable to set the above range in that there is no need to remove the organic solvent by such heating. In the production of the resin, solution polymerization in an organic solvent is a well-known general method. In order to obtain a solid fluorine-containing resin composition, it is necessary to remove the organic solvent used in such solution polymerization.

[0044] In this disclosure, "organic solvent" means a volatile organic compound, which has a boiling point and is in a liquid state at room temperature. The above organic solvent is not particularly limited and may include those commonly used as solvents in the chemical field. Specifically, examples include esters such as ethyl acetate, n-butyl acetate, t-butyl acetate, isopropyl acetate, isobutyl acetate, cellosolve acetate, methoxypropyl acetate, and propylene glycol methyl ether acetate; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; cyclic ethers such as tetrahydrofuran and dioxane; amides such as N,N-dimethylformamide and N,N-dimethylacetamide; aromatic hydrocarbons such as xylene, toluene, solvent naphtha, and coal tar naphtha; glycol ethers such as propylene glycol methyl ether and ethyl cellosolve; diethylene glycol esters such as carbitol acetate; aliphatic hydrocarbons such as n-pentane, n-hexane, n-heptane, n-octane, n-nonane, n-decane, n-undecane, n-dodecane, and mineral spirits; alcohols with four or fewer carbon atoms such as methanol, ethanol, propanol, and butanol; and mixed solvents thereof.

[0045] The amount of organic solvent (C) in the fluororesin composition of this disclosure refers to the value obtained by subtracting the above-mentioned water content from the mass change rate when heated in an electric furnace at 150°C for 1 hour.

[0046] (Shape of the Resin Composition) The shape of the fluororesin composition of this disclosure is not particularly limited, but it is particularly preferred to be in powder form, pellet form, or flake form. That is, pellet-shaped resin is easy to handle and easy to transport and store. Furthermore, it can be easily dissolved in a solvent when used, and its weight can be easily reduced. Specifically for pellet form, the average major diameter of the pellets is preferably 50 mm or less, and more preferably 20 mm or less. On the other hand, the average major diameter of the pellets is, for example, 1 mm or more. The average aspect ratio of the pellets is preferably 2 or less. The average aspect ratio of the pellets is, for example, 1.0 or more. Furthermore, it is preferable that powder with an average major diameter of 1 mm or less accounts for 10% or less of the total. Flake-shaped resin is preferred in that it has excellent resistance to blocking during storage of the resin. Furthermore, it is easy to crush during production.

[0047] The fluororesin composition described above is preferably soluble in parachlorobenzotrifluoride. Parachlorobenzotrifluoride has been increasingly used as a solvent in recent years, and therefore, it is preferable that the composition has excellent solubility in such a solvent. Here, "dissolves" means that when 50 g of the fluororesin copolymer is added to 50 g of parachlorobenzotrifluoride at 25°C, it can be dissolved without any residue.

[0048] The above fluororesin composition is preferably such that, when dissolved in parachlorobenzotrifluoride to a solid content concentration of 50% by mass, the rotational viscosity at 25°C, as measured with a B-type viscometer, is 10,000 mPa·s or less. This is preferable because it allows for suitable use as a paint raw material and further reduces viscosity, thereby enabling high solid differentiation in the paint. The rotational viscosity is more preferably 8,000 mPa·s or less, and even more preferably 7,000 mPa·s or less. The lower limit of the rotational viscosity is not particularly limited, but for example, it is 20 mPa·s or more.

[0049] (Manufacturing Method) The manufacturing method for the resin composition of this disclosure is not particularly limited, but for example, it can be obtained by a manufacturing method that includes: (1) a step of desolving a fluorine-containing resin solution obtained by dissolving a fluorine-containing copolymer (A) in an organic solvent (C) under reduced pressure at a heat transfer medium temperature of 150°C or less, and recovering it as a composition; (2) a step of melting the resin obtained in step (1); and (3) a step of water-cooling and dehydrating the molten resin obtained in step (2). The manufacturing method will be described below step by step.

[0050] (Step 1) Step 1 is a step of desolving a fluorine-containing resin solution obtained by dissolving a fluorine-containing copolymer (A) in an organic solvent (C) by reducing the pressure under a heat transfer medium temperature of 150°C or lower, and recovering it as a composition containing 2% by mass or less of the organic solvent. The fluorine-containing resin solution used in this step may be a resin solution obtained by solution polymerization in an organic solvent (C), or a fluorine-containing resin obtained by other methods dissolved in an organic solvent, or a resin solution obtained by solution polymerization may be subjected to a predetermined treatment.

[0051] Step 1 is a step of desolventing such a fluororesin solution by reducing the pressure under a heat medium temperature of 150°C or lower. This step yields a composition containing 2% by mass or less of an organic solvent. The lower limit of the organic solvent content may be, for example, 0% by mass. "Under a heat medium temperature of 150°C or lower" means that the heat medium used as a heating means in the heating device is 150°C or lower. By desolventing by heating at such a relatively low temperature, thermal decomposition of the resin can be prevented. Since the fluororesin solution of this disclosure has functional groups, it is prone to reactions and high molecular weight formation upon heating. To improve this problem, it is preferable to keep the temperature below 150°C. As for the lower limit of the internal temperature of the resin in Step 1, it is preferable to keep it above 80°C and more preferably above 90°C in order to ensure sufficient desolventing and flow rate / velocity. The upper limit is more preferably below 145°C and even more preferably below 140°C.

[0052] The degree of vacuum in step 1 described above is not particularly limited, but for example, it can be carried out under conditions of a vacuum of 10 Torr or less.

[0053] The apparatus for removing the solvent described above is not particularly limited, but for example, a thin-film forming apparatus consisting of a stirring blade for forming a thin film, a heating means using a heat transfer medium for evaporating the solvent, and a discharge screw for discharging the solvent-soluble fluororesin can be used, and an apparatus can be used to pass a solvent-soluble fluororesin solution through it and remove the solvent within the apparatus. Known apparatuses can be used for this purpose.

[0054] (Step 2) Step 2 is a step in which the fluorine-containing copolymer, from which the solvent has been removed in Step 1, is heated and melted. The method of heating and melting is not particularly limited, but it can be done by kneading machine or the like. The melting temperature is not particularly limited, but it is preferably carried out in the range of glass transition temperature (Tg) + 20°C to Tg + 150°C. In order to increase the fluidity of the resin, ensure the flow rate and flow velocity and reduce the thermal history, it is more preferable to have a temperature of Tg + 30°C or higher, and even more preferable to have a temperature of Tg + 40°C or higher. The upper limit temperature is preferably such that the internal temperature of the resin is 145°C or lower, and more preferably 140°C or lower from the viewpoint of thermal stability.

[0055] (Step 3) Step 3 is a process of water-cooling and dewatering the molten resin obtained in step (2). In the case of pelletization, the molten resin obtained by the above method is extruded in strand form, water-cooled, and then cut to form pellets. In the case of flakeization, the obtained molten resin is cooled into a flat plate form, and then the resin is crushed by impact to form flakes.

[0056] The fluorine-containing copolymer of this disclosure tends to have a relatively low Tg, so cooling is necessary before cutting with a cutter. Such cooling is performed by water cooling, but water cooling causes the fluorine-containing copolymer to contain water. As mentioned above, the fluorine-containing copolymer of this disclosure has a water content within a predetermined range, so when such water cooling is performed, it is preferable to perform the following dehydration. The method for step 3 is not particularly limited, but for example, pelletization can be performed by an underwater cutter. When using an underwater cutter, the temperature of the circulating water is preferably 0 to 30°C, more preferably 0 to 20°C, and the rotation speed of the cutter is preferably 500 to 5000 rpm, more preferably 1500 to 3500 rpm. If the rotation speed is fast relative to the resin extrusion speed, pellets with small particle size and a small aspect ratio tend to be produced, and if the rotation speed is slow relative to the resin extrusion speed, pellets with large particle size and a large aspect ratio can be obtained.

[0057] If the internal temperature of the resin in step 2 is inappropriate, specifically if the internal temperature is too low and the fluidity is too low, or if the internal temperature is too high and the fluidity is too high, continuous extrusion in strand form or continuous cutting with an underwater cutter becomes difficult, so it is necessary to adjust the resin to an appropriate melt viscosity range. Also, if cooling with cooling water is insufficient, the cutting of the resin and the blocking resistance of the resin after cutting will decrease, so it is preferable that the upper limit temperature be below the Tg and melting point.

[0058] In step 3, it is preferable to perform a dewatering step after the cooling step. This is a step to remove water contained in the fluorine-containing copolymer obtained in the cooling step. The dewatering method is not particularly limited and can be performed by centrifugal dewatering, for example. Specifically, a centrifugal dewatering machine manufactured by GALA Corporation can be used. When performing centrifugal dewatering using a centrifugal dewatering machine, the rotation speed is preferably 500 to 10,000 rpm, and more preferably 1,500 to 5,000 rpm. If a sufficient rotation speed cannot be obtained during centrifugal dewatering, the fluorine-containing copolymer will have a high water content after processing, so it is preferable to perform dewatering at a sufficient rotation speed, specifically 500 rpm or more, and more preferably 1,500 rpm or more. If the rotation speed is too high, the obtained resin will be pulverized and its handling properties will decrease, so it is preferable to perform dewatering at less than 10,000 rpm, and more preferably 5,000 rpm or less.

[0059] The method for producing the fluororesin composition of the present disclosure described above is particularly preferably a method that includes a step of removing water from a fluororesin solution obtained by dissolving a fluororesin solution in which a fluororesin copolymer has been dissolved in an organic solvent, under a heat transfer medium temperature of 150°C or lower until the organic solvent is reduced to 2% by mass or less, and then removing water so that the water content is 100 to 3000 ppm.

[0060] (Paint Composition) The above-described fluororesin composition can be suitably used as a resin for paints. Suitable uses include mixing it with a solvent and other co-components to form a resin solution, or using it in combination with a curing agent to form a curable paint.

[0061] When using parachlorobenzotrifluoride (a1) as the solvent, it is also possible to use parachlorobenzotrifluoride (a1), or a mixed solvent of parachlorobenzotrifluoride (a1) and a solvent (a2) with a boiling point of 100°C or less, where the ratio (mass ratio) of (a1) / (a2) in the solvent is (50-100) / (50-0) (excluding 50 / 50).

[0062] In other words, the essential solvent component is parachlorobenzotrifluoride (a1), which has been widely used as a solvent in recent years, and if necessary, a solvent (a2) with a boiling point of 100°C or less may be added to it in a certain proportion. Such a solvent (A) is a solvent composition that has been increasingly used in recent years as parachlorobenzotrifluoride (a1) has become more common, and the composition of this disclosure can accommodate such a solvent composition.

[0063] (Solvent (a2) with a boiling point of 100°C or less) In this disclosure, the solvent may contain only parachlorobenzotrifluoride (a1), or it may be a mixed solvent containing a predetermined proportion of solvent (a2) with a boiling point of 100°C or less.

[0064] Such solvents are not particularly limited and can be general ones used in the field of paints. Specifically, examples include t-butylacetic acid, dimethyl carbonate, methyl acetate, ethyl acetate, isopropyl acetate, acetone, methyl ethyl ketone, tetrahydrofuran, n-pentane, n-hexane, n-heptane, etc. Two or more of these may be used in combination.

[0065] When using the solvent (a2) with a boiling point of 100°C or lower, the amount used is preferably such that the ratio (mass ratio) of (a1) / (a2) in the solvent is (50-100) / (50-0) (excluding 50 / 50). If (a2) is added in a ratio exceeding 50 / 50, the paintability will decrease, and a good paint film cannot be formed. It is also acceptable to not add any solvent (a2) with a boiling point of 100°C or lower at all.

[0066] The above paint composition may contain solvents other than the above solvents (a1) and (a2). Examples include esters such as n-butyl acetate, isobutyl acetate, cellosolve acetate, methoxypropyl acetate, propylene glycol methyl ether acetate, and ethyl 3-ethoxypropionate; ketones such as methyl isobutyl ketone and cyclohexanone; cyclic ethers such as dioxane; amides such as N,N-dimethylformamide and N,N-dimethylacetamide; aromatic hydrocarbons such as xylene, toluene, solvent naphtha, and coal tar naphtha; glycol ethers such as propylene glycol methyl ether and ethyl cellosolve; diethylene glycol esters such as carbitol acetate; aliphatic hydrocarbons such as n-octane, n-nonane, n-decane, n-undecane, n-dodecane, and mineral spirits; and mixed solvents thereof. However, the content of other solvents is preferably 10% by mass or less of the total amount of solvent. The solvent contained in the composition greatly affects the coating performance. Therefore, even if other solvents are used, it is preferable that they are used within a range that does not impair the performance of the composition of this disclosure.

[0067] (Other Components) The compositions of this disclosure may contain other components as needed. Other components that may be incorporated into the compositions of this disclosure are not limited to, but include, for example, curing agents, curing catalysts, pigments, curing accelerators, curing retarders, pigment dispersants, defoamers, leveling agents, ultraviolet absorbers, light stabilizers, thickeners, adhesion improvers, matting agents, and the like.

[0068] (Curing agent) As described above, the composition of this disclosure may consist of a hydroxyl group-containing polymer as a constituent unit. In this case, the curing reaction may be generated by this hydroxyl group.

[0069] The curing agents that can be used in the compositions of this disclosure are not particularly limited, and compounds that crosslink by reacting with the curable functional groups (e.g., hydroxyl groups or carboxyl groups) of the fluorine-containing polymer can be used. Examples include isocyanates, amino resins, acid anhydrides, polyepoxy compounds, isocyanate group-containing silane compounds, carbodiimides, oxazolines, aziridines, and the like.

[0070] (Curing catalyst) When using the above curing agent, a curing catalyst may be used depending on the type of curing agent used.

[0071] (Pigments) The pigments that can be used in the compositions of this disclosure are not particularly limited and include coloring pigments (for example, inorganic pigments such as titanium dioxide, red iron oxide, yellow iron oxide, and carbon black, and organic pigments such as phthalocyanine blue, phthalocyanine green, quinacridone-based red pigments, and isoindolinone-based yellow pigments); extender pigments such as talc, silica, and calcium carbonate; metal powders such as aluminum powder and stainless steel powder; and, if desired, one or more additives such as mica powder, leveling agents, UV absorbers, heat degradation inhibitors, and foaming inhibitors may be added. It may also be used as a clear coating that does not contain pigments.

[0072] (Manufacturing Method) The composition of this disclosure does not particularly limit the method of manufacturing, and can be obtained by a general method of mixing the components constituting the composition. As described above, the composition can be prepared by mixing the components at the painting site.

[0073] Furthermore, if a hardening agent is used, it may be a two-component paint composition that is mixed during painting.

[0074] (Compositions for Paints) The compositions of this disclosure can be used as compositions for paints. When used as a composition for paints, the painting method is not particularly limited and examples include air spray painting, airless spray painting, rotary atomization painting, curtain coat painting, dip painting, roller painting, brush painting, and painting with a doctor blade.

[0075] The coating compositions of this disclosure may be used in combination with other coating compositions to form a multi-layer coating film.

[0076] (Applications) The paint composition disclosed herein is not particularly limited in its applications and can be suitably used, for example, as a heavy-duty anticorrosive paint in the construction industry for bridges, steel towers, high-rise buildings, etc. The substrate is also not particularly limited and can be used for coating metals (iron, copper, aluminum, etc.), concrete, wood, plastics, etc. Furthermore, it can also be used in the fields of inks and electronic materials.

[0077] 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.

[0078] The present disclosure will now be described in detail based on the following examples. In the following examples, unless otherwise specified, "parts" and "%" refer to "parts by mass" and "% by mass," respectively.

[0079] (Production Example 1: Preparation of Fluorine-Containing Copolymer Solution A) 2500 g of butyl acetate, 1032 g of vinyl neononanoate (Veova9), 264 g of 4-hydroxybutyl vinyl ether (HBVE), and 13.8 g of crotonic acid (CTA) were added to a 6000 ml stainless steel autoclave. The autoclave was then subjected to reduced pressure nitrogen purging, and 684 g of tetrafluoroethylene (TFE) was added. The temperature was raised to 60.0°C under stirring, and 30 g of peroxide-based polymerization initiator was added to start polymerization. The reaction was stopped when the reactor pressure decreased from 1.0 MPaG to 0.4 MPaG, and a solution containing polymers with TFE / HBVE / vinyl neononanoate / CTA ratios of 45.5 / 15.3 / 37.9 / 1.3 mol% was obtained. The obtained solution was concentrated in an evaporator to remove a predetermined amount of butyl acetate, and fluorine-containing copolymer solution A with a solid content of 65% was prepared.

[0080] (Preparation Example 2: Preparation of Fluorine-Containing Copolymer Solution B) A solution containing polymers in the same proportions as in Preparation Example 1 was obtained: chlorotrifluoroethylene (CTFE) / cyclohexyl vinyl ether (CHVE) / ethyl vinyl ether (EVE) / 4-hydroxybutyl vinyl ether (HBVE) = 48.4 / 9.5 / 32.9 / 9.2 mol%. The obtained solution was concentrated using an evaporator to prepare fluorine-containing copolymer solution B with a solid content of 50%.

[0081] The properties of the resin composition and the properties of the solutions obtained from the fluorine-containing copolymer solutions A and B were analyzed according to the methods described below. The results are shown in Table 1.

[0082] (Analysis of monomer unit content constituting the copolymer) Elemental analysis was performed on the fluororesin composition, and the measured fluorine content (mass%) was determined. １ H-NMR, １９ The content (mol%) of each monomer unit was calculated from compositional analysis using F-NMR spectroscopy.

[0083] (Method for measuring gravimetric molecular weight Mw) Measuring device: GPC (model: HLC-8420) manufactured by Tosoh Corporation. Measurement conditions: Three TSKgel SuperMultiporeHZ-M columns were used. Tetrahydrofuran was used as the eluent, and polystyrene with a known molecular weight was used as the standard molecular weight sample.

[0084] (Hydroxyl Value) The hydroxyl value (unit: mgKOH / g) was calculated from the above content analysis results of the fluororesin composition using formula (1). Hydroxyl value = [OH (mass%)] × [KOH molecular weight] ÷ [OH (equivalent)] × 1000 ÷ 100 ... (1) In formula (1), "KOH molecular weight" is 56.1. In formula (1), "OH (mass%)" represents the weight ratio of all hydroxyl group-containing monomers to all monomers, calculated from the content (mol%) of each monomer unit calculated in the above content analysis. In formula (1), "OH (equivalent)" represents the value calculated from formula (2). [OH (equivalent)] = [Molecular weight of hydroxyl group-containing monomer] ÷ [Number of hydroxyl groups in one molecule of hydroxyl group-containing monomer] ... (2)

[0085] (Acid Value) The obtained fluorine-containing copolymer solution was measured by potentiometric titration in accordance with JIS K 5601, and the acid value (mgKOH / g) per gram of fluorine-containing copolymer was calculated using the value of the heating residue (mass%).

[0086] (Heating residue of fluorine-containing copolymer solution) Weigh 2 g of fluorine-containing copolymer solution into an aluminum cup and measure the initial weight (W ０ (=2g) and the remaining weight W after heating in an electric furnace at 150°C for 2 hours. １ The ratio (heating residue = 100 × residual weight W) １ / Initial weight W ０ The heating residue (mass%) of the fluorine-containing copolymer solution was calculated from the above.

[0087]

[0088] (Example 1) A fluorine-containing copolymer solution A with a solid content of 65% was preheated to 50°C and fed from the top into a vertical thin film dryer with an inlet temperature of 120°C and a vacuum of 10 Torr at a flow rate of 45 L / hr. The desolvation process was carried out in the thin film dryer with the temperatures of the inlet temperature at 120°C, the upper temperature at 90°C, and the lower temperature at 90°C, and n-butyl acetate was recovered. The fluorine-containing copolymer composition after the desolvation process was extruded through an extruder directly from the die plate into cooling water at 10-20°C, and cutting with a pelletizer in the water (underwater cutter) was performed to carry out desolvation and solidification (cooling and pelletization). At this time, the die temperature was set to 150°C, and the temperature of the molten resin composition near the die plate was 130°C. The rotation speed of the pelletizer in the underwater cutter was kept constant at 2500 rpm. After the solidification process in water, the cooled water containing the solid composition was passed through a centrifugal dehydrator (1800 rpm) to dehydrate it, yielding a homogeneous solid fluorine-containing copolymer composition A1 containing trace amounts of organic solvent and water. The obtained fluorine-containing copolymer composition A1 was filled into polyethylene bags and stored at 25°C. The yield of the composition per hour was 28-32 kg / hr. The appearance and various physical properties of the obtained fluorine-containing copolymer composition A1 were evaluated. The results are shown in the table below.

[0089] (Examples 2-9) In the same manner as in Example 1, fluorine-containing copolymer solution A was subjected to solvent removal, solidification (cooling and pelletization), and dehydration treatment under the conditions described in Tables 2 and 3 to obtain homogeneous solid fluorine-containing copolymer compositions A2-A9 containing trace amounts of organic solvent and water. The obtained fluorine-containing copolymer compositions A2-A9 were evaluated for appearance and various physical properties. The evaluation results are shown in the table below.

[0090] (Example 10) In the same manner as in Example 1, the fluorine-containing copolymer solution B was subjected to solvent removal, solidification (cooling and pelletization), and dehydration treatment under the conditions described in Table 3 to obtain a homogeneous solid fluorine-containing copolymer composition B1 containing trace amounts of organic solvent and water. The obtained fluorine-containing copolymer composition B1 was evaluated for its appearance and various physical properties. The evaluation results are shown in the table below.

[0091] (Example 11) Solution A containing fluorine was dried at 150°C for 4 hours using a vacuum dryer and allowed to cool in a desiccator to obtain fluorine-containing copolymer composition A14. Fluorine-containing copolymer composition A14 was in the form of a mass containing trace amounts of organic solvent and water.

[0092] (Comparative Example 1) In the same manner as in Example 1, under the conditions described in Table 3, the fluorine-containing copolymer solution A was subjected to a desolvent process under reduced pressure using a thin film dryer and pelletized using an underwater cutter in cooling water. After that, 100 g of the aqueous solid composition was recovered without passing it through a centrifugal dehydrator. The recovered aqueous composition was spread on a mesh with a mesh opening of 1000 μm to drain the water, and then spread in a 300 mm x 300 mm PP container so that the pellets did not overlap, and dried by standing in an electric furnace with air circulation at 25°C. After 96 hours, it was removed from the electric furnace and 70 g of fluorine-containing copolymer composition A10 was obtained. After removal, it was filled into a polyethylene bag and stored at 25°C. The obtained fluorine-containing copolymer composition A10 was evaluated for appearance and various physical properties. The results are shown in the table below.

[0093] (Comparative Example 2) In the same manner as in Example 1, a fluorine-containing copolymer solution A was subjected to a desolventization process under reduced pressure using a thin-film dryer and pelletization with an under-water cutter in cooling water under the conditions shown in Table 3. Next, in the same manner as in Comparative Example 1, without passing through a centrifugal dehydrator, the recovered water-containing composition was dried using an air-circulation electric furnace at 25°C. After 48 hours, it was taken out from the electric furnace, and 70 g of a fluorine-containing copolymer composition A11 was obtained. After taking out, it was filled in a polyethylene bag and stored at 25°C. Appearance evaluation and various physical property evaluations were performed on the obtained fluorine-containing copolymer composition A11. The results are shown in the following table.

[0094] (Comparative Example 3) In the same manner as in Example 1, a fluorine-containing copolymer solution A was subjected to a desolventization process under reduced pressure using a thin-film dryer and pelletization with an under-water cutter in cooling water under the conditions shown in Table 3. Next, in the same manner as in Comparative Examples 1 and 2, without passing through a centrifugal dehydrator, the recovered water-containing composition was dried using an air-circulation electric furnace at 25°C. After 12 hours, it was taken out from the electric furnace, and 70 g of a fluorine-containing copolymer composition A12 was obtained. After taking out, it was filled in a polyethylene bag and stored at 25°C. Appearance evaluation and various physical property evaluations were performed on the obtained fluorine-containing copolymer composition A12. The results are shown in the following table.

[0095] (Evaluation Method) (Solid Appearance) For the obtained solid fluorine-containing resin composition, it was visually classified as to whether it was in pellet form, lump form, uniform shape, or non-uniform shape. Appearance observation was carried out under a 25°C environment.

[0096] (Pellet Shape) When the obtained solid fluorine-containing resin composition was in pellet shape, the shapes of 20 randomly sampled pellets were measured, and the major diameter and aspect ratio were measured. The average values were taken as the major diameter and aspect ratio.

[0097] (Heating Residue of Fluorine-containing Resin Composition) 2 g of the fluorine-containing resin composition was weighed into an aluminum cup, and the ratio of the initial weight (W ０ = 2 g) to the residue weight W １ after heating at 150°C for 2 hours in an electric furnace (heating residue = 100 × residue weight W １ / initial weight W ０The heating residue (unit: mass%) of the fluororesin composition was calculated from the above. The measured heating residue corresponds to the content of the fluororesin copolymer (A).

[0098] (Weight loss during heating) The weight loss during heating (unit: mass%) was calculated using the formula "Weight loss during heating = 100 - residual weight after heating".

[0099] (Moisture Content) The moisture content (in ppm) was measured using the Karl Fischer method. The measured moisture content (moisture content in the table) corresponds to the percentage of water (B).

[0100] (Residual Solvent Amount) The residual solvent amount (unit: mass%) was calculated using the formula "Residual solvent amount = 100 - Heating residue - (Water content / 10000) = Weight loss during heating - (Water content / 10000)". The residual solvent amount corresponds to the content of organic solvent (C).

[0101] (Weight-average molecular weight Mw and Mw increase rate) Using the weight-average molecular weight Mw measurement method described above, the weight-average molecular weight Mw of the fluorine-containing copolymer before solvent removal-solidification (cooling and pelletization) and dehydration treatment (Mw before treatment) and the weight-average molecular weight Mw of the fluorine-containing copolymer after treatment (Mw after treatment) were measured. The Mw increase rate (unit: %) was calculated from the formula "Mw increase rate = 100 × (Mw after treatment) / (Mw before treatment)".

[0102]

[0103]

[0104]

[0105]

[0106] The pellets obtained using the above method were evaluated based on the following method.

[0107] (Transparency and Solubility of Solution) 50 g of solid resin (each of the fluorine-containing copolymer compositions prepared in Examples 1-11 and Comparative Examples 1-3) and 50 g of solvent (parachlorobenzotrifluoride (PCBTF) or tert-butyl acetate) were weighed into a poly bottle. The container was rotated for 24 hours at 25°C using a benchtop mixer to dissolve the resin and obtain a resin solution with a solid content of 50% by mass. The obtained solution was stirred at 1200 rpm for 10 minutes using a stirrer, transferred to a glass tube container, and allowed to stand at room temperature for 24 hours. After that, the transparency of the liquid was visually checked to ensure there was no turbidity. The liquid was filtered to check for insoluble matter or gels and to confirm its solubility.

[0108] (Rotational Viscosity) The rotational viscosity of the resin solution obtained above was measured using a Type B rotational viscometer at a solution temperature of 25°C.

[0109] (Solution Turbidity) The turbidity of the resin solution obtained above was measured using a turbidimeter (integrating sphere turbidimeter PT-200: Nitto Seiko Analytic Co., Ltd.). Cell used: T-type cell T-10 (10 mm cell). The cell was filled to about 80% capacity with the solution, set in the apparatus, and the turbidity (unit: ppm) was measured after 1 minute.

[0110] (Example of coating film manufacturing) A clear coating film was prepared using the resin solution prepared above. The coating film was applied to a glass plate with an applicator wet thickness of 8 milliliters at 25°C and dried at 25°C for 24 hours. The resulting coating film was visually evaluated for any defects in film formation such as blemishes, repellency, and shrinkage, as well as for the transparency of the coating film.

[0111] (Film-forming properties) No abnormalities: ○ (Good) Slight occurrence of blemishes, repulsion, shrinkage, etc.: △ (Normal) Significant occurrence of blemishes, repulsion, shrinkage, etc.: × (Poor)

[0112] (Appearance: Transparency of the coating) Transparent: ○ (Good) Slightly cloudy: △ (Average) Severely cloudy: × (Poor)

[0113]

[0114]

[0115] From the results in Tables 2 to 7 above, it is clear that the compositions of this disclosure have remarkably superior effects.

[0116] The compositions of this disclosure can be suitably used as paint compositions.

Claims

1. A fluorine-containing resin composition characterized by containing 95% by mass or more of a fluorine-containing copolymer (A) containing monomers having functional groups as constituent units, and 100 to 3000 ppm of water (B) as constituent components.

2. The fluororesin composition according to claim 1, further containing 0.1 to 2% by mass of an organic solvent (C).

3. The fluorine-containing polymer (A) contains monomers having hydroxyl groups as constituent units, and the hydroxyl value of the fluorine-containing polymer is 45 mgKOH / g or more, according to claim 1 or 2.

4. The fluorine-containing resin composition according to any one of claims 1 to 3, wherein the fluorine-containing copolymer (A) comprises a fluoroolefin unit and at least one monomer unit selected from the group consisting of vinyl esters, vinyl ethers, (meth)acrylic esters, and allyl ethers.

5. The fluorine-containing resin composition according to any one of claims 1 to 4, wherein the fluorine-containing copolymer (A) contains monomers having an acid value as constituent units, and the acid value of the fluorine-containing copolymer (A) is 1.0 mg KOH / g or more.

6. The fluorine-containing resin composition according to any one of claims 1 to 5, wherein the fluorine-containing copolymer (A) has a weight-average molecular weight (Mw) on a polystyrene basis measured by GPC of 50,000 or less.

7. The fluorine-containing polymer (A) is soluble in parachlorobenzotrifluoride, and the rotational viscosity at 25°C measured with a B-type viscometer when dissolved in parachlorobenzotrifluoride to a solid content concentration of 50% by mass is 10,000 mPa·s or less, according to any one of claims 1 to 6.

8. The fluororesin composition according to any one of claims 1 to 7, wherein the organic solvent (C) comprises at least one selected from the group consisting of n-butyl acetate, ethyl acetate, xylene, toluene, methyl ethyl ketone, methyl isobutyl ketone, acetone, and alcohols having 4 or fewer carbon atoms.

9. The fluororesin composition according to any one of claims 1 to 8, which is in the form of flakes, powder, or pellets in a 25°C environment.

10. A fluororesin composition according to any one of claims 1 to 9, wherein the pellet shape is pellet-shaped, and the average major diameter of the pellet is 20 mm or less, and the average aspect ratio is 2 or less.

11. A fluorine-containing resin composition according to any one of claims 1 to 10, comprising: the fluorine-containing copolymer (A) in a content of 99.0 to 99.9% by mass; the water (B) in a content of 100 to 3000 ppm; and the organic solvent (C) in a content of 0.1 to 1.0% by mass, wherein the fluorine-containing copolymer (A) comprises a fluoroolefin unit, at least one monomer unit selected from the group consisting of vinyl monomers having hydroxyl groups and vinyl monomers having carboxyl groups, and at least one monomer unit selected from the group consisting of alkyl vinyl esters and alkyl vinyl ethers.

12. A method for producing a fluororesin composition according to any one of claims 1 to 11, characterized by comprising the step of desolventing a fluororesin solution obtained by dissolving the fluororesin in an organic solvent (C) in a fluororesin solution at a heat transfer medium temperature of 150°C or lower until the amount of organic solvent (C) is 2% by mass or less, and then removing water so that the water content is 100 to 3000 ppm.

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