Fluoropolymer composition for coating

Abstract

Provided is a fluorine-containing polymer composition for a coating material, the fluorine-containing polymer composition being capable of suppressing the formation of water and coloration after storage and having excellent leveling properties of a coating film formed using a coating material when the fluorine-containing polymer composition is mixed with a solvent for a coating material to produce a coating material. The fluorine-containing polymer composition for a coating according to the present invention comprises a fluorine-containing polymer, cyclohexanone, and a solvent different from the cyclohexanone, the fluorine-containing polymer comprising a unit based on a fluoroolefin and a unit based on a monomer having no fluorine atom, the total amount of the cyclohexanone and the solvent is 10% by mass or more with respect to the total mass of the fluorine-containing polymer composition for a coating material, and the content of the cyclohexanone is 0.5-2.0% by mass with respect to the total mass of the fluorine-containing polymer composition for a coating material.

Description

Technical Field

[0001] The present invention relates to fluorine-containing polymer compositions for coatings. Background Art

[0002] Coatings containing fluorinated polymers can form coating films having excellent weather resistance and the like, and are therefore used in a variety of fields. As coatings containing such fluorinated polymers, Patent Document 1 discloses the use of a composition containing a fluorinated polymer and butyl acetate as a solvent as a coating, wherein the fluorinated polymer contains a perhalogenated olefin unit, a vinyl ester unit containing neither a hydroxyl group nor an aromatic ring, and a hydroxyl group-containing monomer unit.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: International Publication No. 2017 / 155022 Summary of the invention

[0006] Problem that the invention aims to solve

[0007] In recent years, there has been a demand for further improvement in the leveling properties of coating films obtained using coating materials containing fluorinated polymers. The present inventors evaluated coating films formed using the coating material described in Patent Document 1 and found that there is room for improvement in the leveling properties.

[0008] In addition, a coating material comprising a fluorinated polymer may be produced by further adding a coating material solvent to a fluorinated polymer composition for coating material comprising a fluorinated polymer and a small amount of solvent so as to obtain a suitable viscosity for the coating material.

[0009] Such a fluorinated polymer composition for coating may be stored for a long period of time before production of coating. Therefore, there is a demand for a fluorinated polymer composition for coating in which coloration is suppressed after storage.

[0010] Furthermore, the fluorinated polymer composition for coatings is required to be less likely to absorb water because it may cause turbidity of the coating film or the like.

[0011] The present invention has been made in view of the above problems, and aims to provide a fluorinated polymer composition for coatings which can suppress coloration after water inclusion and storage and which, when mixed with a coating solvent to produce a coating, provides a coating film having excellent leveling properties.

[0012] Solutions for solving problems

[0013] The present inventors have conducted intensive studies and found that the above-mentioned problems can be solved by the following configuration.

[0014] [1] A fluorinated polymer composition for coating, comprising a fluorinated polymer, cyclohexanone, and a solvent different from the cyclohexanone, wherein the fluorinated polymer comprises units based on a fluoroolefin and units based on a monomer having no fluorine atoms, wherein the total amount of the cyclohexanone and the solvent is 10% by mass or more relative to the total mass of the fluorinated polymer composition for coating, and the content of the cyclohexanone is 0.5 to 2.0% by mass relative to the total mass of the fluorinated polymer composition for coating.

[0015] [2] The fluorinated polymer composition for coating according to [1], wherein the fluoroolefin is CF 2 =CFCl.

[0016] [3] The fluorinated polymer composition for coating according to [1] or [2], wherein the units based on a monomer having no fluorine atom include at least one of a unit based on a monomer having no fluorine atom and no reactive group and a unit based on a monomer having a reactive group and having no fluorine atom.

[0017] [4] The fluorinated polymer composition for coating according to [3], wherein the reactive group is a hydroxyl group.

[0018] [5] The fluorinated polymer composition for coating according to any one of [1] to [4], wherein the total amount of the cyclohexanone and the solvent is 70% by mass or less based on the total mass of the fluorinated polymer composition for coating.

[0019] [6] The fluorinated polymer composition for coating according to any one of [1] to [5], wherein the total amount of the cyclohexanone and the solvent is 30% by mass or more based on the total mass of the fluorinated polymer composition for coating.

[0020] Effects of the Invention

[0021] According to the present invention, there can be provided a fluorinated polymer composition for coatings which is suppressed from containing water and coloring after storage and which, when mixed with a solvent for coatings to produce a coating, provides a coating film having excellent leveling properties. DETAILED DESCRIPTION

[0022] The meanings of the terms used in the present invention are as follows.

[0023] The numerical range expressed using "to" means a range including the numerical values ​​described before and after "to" as the lower limit and the upper limit.

[0024] Unit refers to the general term for atomic groups based on one molecule of the monomer directly formed by polymerization of the monomer and atomic groups obtained by chemical conversion of a part of the atomic groups. The content (mol %) of each unit relative to all units contained in the polymer can be determined by analyzing the polymer by nuclear magnetic resonance spectroscopy, or by the input amount of the components used in the production of the polymer.

[0025] “(Meth)acrylic acid” is a general term for “acrylic acid” and “methacrylic acid”, and “(meth)acrylate” is a general term for “acrylate” and “methacrylate”.

[0026] The hydrolyzable silyl group is a group that can undergo a hydrolysis reaction to form a silanol group. The acid value and the hydroxyl value are values ​​measured according to the method of JIS K 0070-3 (1992).

[0027] The glass transition temperature (Tg) is the midpoint glass transition temperature of a polymer as measured by differential scanning calorimetry (DSC).

[0028] The number average molecular weight (Mn) is a value measured by gel permeation chromatography using polystyrene as a standard substance.

[0029] The fluorinated polymer composition for coating of the present invention (hereinafter also referred to as the present composition) comprises a fluorinated polymer, cyclohexanone and a solvent different from the above-mentioned cyclohexanone (hereinafter also referred to as other solvents), wherein the fluorinated polymer comprises a unit based on a fluoroolefin and a unit based on a monomer having no fluorine atom. In addition, the total amount of the above-mentioned cyclohexanone and the above-mentioned other solvent is 10% by mass or more relative to the total mass of the present composition. In addition, the content of the above-mentioned cyclohexanone is 0.5 to 2.0% by mass relative to the total mass of the present composition.

[0030] The present composition can suppress coloration after storage. The reason may not be clear, but it is presumed that the reason is that by making the content of cyclohexanone in the present composition 2.0 mass % or less, the generation of compounds that cause coloration over time, such as dimers of cyclohexanone, metal components that may be contained in the composition (e.g., potassium ions derived from potassium carbonate used in production) and chelates of cyclohexanone, can be suppressed.

[0031] The reason for this is not necessarily clear, but it is presumed that this is because the total amount of cyclohexanone and other solvents in the present composition is set to 10% by mass or more, which makes it difficult to introduce water into the system.

[0032] In addition, the coating film (hereinafter also referred to as the present coating film) formed by using the coating (hereinafter also referred to as the present coating film) comprising the present composition and the coating solvent has excellent leveling properties. The reason for this may not be clear, but it is speculated that by making the content of cyclohexanone in the present composition 0.5% by mass or more, the function of cyclohexanone with excellent compatibility with the fluoropolymer can be well exerted, and the fluoropolymer is well dissolved in the coating film, resulting in an improvement in the leveling properties of the coating film (i.e., the smoothness of the coating film).

[0033] The fluorine-containing polymer comprises a unit based on a fluoroolefin (hereinafter also referred to as a unit F) and a unit based on a monomer having no fluorine atom (hereinafter also referred to as a unit A).

[0034] Fluoroolefins are olefins in which one or more hydrogen atoms are substituted with fluorine atoms. One or more hydrogen atoms of the fluoroolefin that are not substituted with fluorine atoms may be substituted with chlorine atoms. The carbon number of the fluoroolefin is preferably 2 to 6, more preferably 2 to 4.

[0035] Examples of fluoroolefins include CF 2 =CF 2 CF 2 =CFCl, CF 2 =CHF, CH 2 =CF 2 CF 2 =CFCF 3 CF 3 -CH=CHF、CF 3 -CF=CH 2 From the viewpoint of weather resistance and polymerizability with monomers other than fluoroolefins, fluoroolefins are preferably CF 2 =CF 2 or CF 2 =CFCl, more preferably CF 2 =CFCl.

[0036] Two or more fluoroolefins may be used in combination.

[0037] From the viewpoint of weather resistance of the present coating film, the content of the unit F is preferably from 20 to 70 mol %, more preferably from 30 to 60 mol %, further preferably from 45 to 55 mol %, based on all units contained in the fluorinated polymer.

[0038] Unit A preferably includes: at least one of a unit (hereinafter also referred to as unit A1) based on a monomer having no fluorine atoms and reactive groups (hereinafter also referred to as monomer a1), and a unit (hereinafter also referred to as unit A2) based on a monomer having a reactive group and no fluorine atoms (hereinafter also referred to as monomer a2).

[0039] Specific examples of the reactive group include a hydroxyl group, an amino group, an epoxy group, an oxetanyl group, a hydrolyzable silyl group, a sulfo group, and a carboxyl group. It should be noted that the sulfo group and the carboxyl group can be ionized to form -SO 3 - or -COO - , can also be salted to become -SO 3 - Na + or -COO - Na + wait.

[0040] The monomer a1 preferably comprises at least one selected from the group consisting of vinyl ethers, vinyl esters, allyl ethers, allyl esters and (meth)acrylates, and more preferably one or both of vinyl ethers and vinyl esters from the viewpoint of copolymerizability with fluoroolefins and weather resistance of the fluorinated polymer.

[0041] Specific examples of monomer a1 include ethyl vinyl ether, tert-butyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexyl vinyl ether, cyclohexyl methyl vinyl ether, vinyl acetate, vinyl pivalate, vinyl neononanoate (trade name VeoVa9 from HEXION), vinyl neodecanoate (trade name VeoVa10 from HEXION), vinyl versatate, vinyl benzoate, vinyl tert-butyl benzoate, tert-butyl (meth)acrylate, and benzyl (meth)acrylate.

[0042] Two or more monomers a1 may be used in combination.

[0043] When the fluorinated polymer contains the unit A1, the content of the unit A1 is preferably from 5 to 60 mol%, more preferably from 10 to 50 mol%, based on all the units contained in the fluorinated polymer.

[0044] When the fluorinated polymer includes unit A2, the fluorinated polymer may have a part or all of the reactive groups in unit A2 in a state in which it has reacted with other components (e.g., a curing agent, etc.), or may have it in a state in which it has not reacted with other components, preferably in a state in which it has not reacted with other components. That is, the fluorinated polymer in the present composition may exist in a state in which it has a crosslinked structure based on a curing agent, or may exist in a state in which it does not have a crosslinked structure.

[0045] Unit A2 may be a unit obtained by converting a unit based on a monomer having a reactive group into a different reactive group in a fluoropolymer containing a unit. Such a unit may be a unit obtained by reacting a polycarboxylic acid, an anhydride thereof, etc. with a fluoropolymer containing a unit having a hydroxyl group, and converting a part or all of the hydroxyl groups into carboxyl groups.

[0046] The unit A2 preferably has a hydroxyl group or a carboxyl group as a reactive group, and more preferably has a hydroxyl group.

[0047] Examples of the monomer a2 having a hydroxyl group include vinyl ethers, vinyl esters, allyl ethers, allyl esters, (meth)acrylates, or allyl alcohols having a hydroxyl group. The monomer a2 having a hydroxyl group is preferably hydroxyvinyl ether or hydroxyallyl ether.

[0048] As the monomer a2 having a hydroxyl group, preferably a monomer of formula X 1 -Z 1 The monomers shown.

[0049] X 1 Preferably CH 2 =CHC(O)O-, CH 2 =C(CH 3 )C(O)O-、CH 2 =CHOC(O)-, CH 2 =CHCH 2 OC(O)-、CH 2 =CHO- or CH 2 =CHCH 2 O-, CH 2 =CHO- or CH 2 =CHCH 2 O-.

[0050] Z 1 It is a monovalent organic group having 2 to 42 carbon atoms and having a hydroxyl group. The organic group may be linear or branched. In addition, the organic group may be formed of a ring structure or may contain a ring structure.

[0051] As the organic group, an alkyl group having 2 to 6 carbon atoms and having a hydroxyl group, an alkyl group including a cycloalkylene group having 6 to 8 carbon atoms and having a hydroxyl group, or a polyoxyalkylene group having a hydroxyl group is preferred.

[0052] Specific examples of the monomer a2 having a hydroxyl group include CH 2 =CHO-CH 2 -cycloC 6 H 10 -CH 2 OH, CH 2 =CHCH 2 O-CH 2 -cycloC 6 H 10 -CH 2 OH, CH 2 =CHO-CH 2 -cycloC 6 H 10 -CH2 -(OCH 2 CH 2 ) 15 OH, CH 2 =CHOCH 2 CH 2 OH, CH 2 =CHCH 2 OCH 2 CH 2 OH, CH 2 =CHOCH 2 CH 2 CH 2 CH 2 OH and CH 2 =CHCH 2 OCH 2 CH 2 CH 2 CH 2 OH.

[0053] It should be noted that “-cycloC 6 H 10 -" indicates cyclohexylene, "-cycloC 6 H 10 -" is usually a 1,4-bonding site.

[0054] Examples of the monomer a2 having a carboxyl group include unsaturated carboxylic acid, (meth)acrylic acid, and a monomer obtained by reacting a hydroxyl group of a monomer having a hydroxyl group with a carboxylic anhydride.

[0055] Specific examples of the monomer a2 having a carboxyl group include CH 2 =CHCOOH, CH(CH 3 )=CHCOOH、CH 2 =C(CH 3 )COOH, HOOCCH=CHCOOH, CH 2 =CH(CH 2 ) n11 A monomer represented by COOH (wherein n11 represents an integer of 1 to 10), CH 2 =CHO(CH 2 ) n12 OC(O)CH 2 CH 2 A monomer represented by COOH (wherein n12 represents an integer of 1 to 10).

[0056] Two or more monomers a2 may be used in combination.

[0057] When the fluorinated polymer contains the unit A2, the content of the unit A2 is preferably from 0.1 to 45 mol %, more preferably from 1 to 35 mol %, further preferably from 5 to 25 mol %, based on all the units contained in the fluorinated polymer.

[0058] The fluorinated polymer is preferably a copolymer containing 20 to 70 mol%, 5 to 60 mol%, 0.1 to 45 mol% of units F, units A1 and units A2 in order relative to all units contained in the fluorinated polymer, and more preferably a copolymer containing 30 to 60 mol%, 10 to 50 mol%, 1 to 35 mol% of units F, units A1 and units A2 in order. In addition, the fluorinated polymer is further preferably composed of units F, units A1 and units A2.

[0059] The Tg of the fluorinated polymer is preferably from 0 to 120°C, more preferably from 10 to 70°C, from the viewpoint of hardness of the coating film.

[0060] From the viewpoint of weather resistance of the coating film, Mn of the fluorinated polymer is preferably from 1,000 to 200,000, more preferably from 5,000 to 100,000, further preferably from 8,000 to 50,000.

[0061] When the fluorinated polymer has a hydroxyl value, the hydroxyl value of the fluorinated polymer is preferably 1 to 200 mgKOH / g, more preferably 5 to 100 mgKOH / g, further preferably 40 to 60 mgKOH / g, from the viewpoint of durability of the coating film.

[0062] When the fluorinated polymer has an acid value, the acid value of the fluorinated polymer is preferably from 1 to 30 mgKOH / g, more preferably from 1 to 10 mgKOH / g, from the viewpoint of pigment dispersibility.

[0063] Examples of methods for producing the fluorinated polymer include solution polymerization, emulsion polymerization, and suspension polymerization, and solution polymerization is preferred from the viewpoint of water resistance. Therefore, the fluorinated polymer is preferably produced by polymerizing each monomer in the presence of a polymerization solvent.

[0064] During the polymerization, a polymerization initiator, a chain transfer agent, a stabilizer, an acid absorbent, etc. may be added as needed.

[0065] The content of cyclohexanone is 0.5 to 2.0% by mass relative to the total mass of the present composition, preferably 0.7% by mass or more, more preferably 1.0% by mass or more, from the viewpoint of better leveling properties of the present coating, and preferably 1.8% by mass or less, more preferably 1.5% by mass or less, from the viewpoint of further suppressing coloration of the present composition after storage.

[0066] Cyclohexanone may be a polymerization solvent for producing fluorine-containing polymers.

[0067] The other solvent contained in the present composition is a solvent different from cyclohexanone. The other solvent may be a polymerization solvent used for producing the fluorine-containing polymer.

[0068] Examples of other solvents include ketone solvents (except cyclohexanone), ester solvents, hydrocarbon solvents, alcohol solvents, glycol ether solvents, and glycol ester solvents.

[0069] Specific examples of the ketone solvent include acetone, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, and diacetone alcohol.

[0070] Specific examples of the ester solvent include ethyl acetate and butyl acetate.

[0071] Specific examples of the hydrocarbon solvent include hexane, heptane, cyclohexane, and xylene.

[0072] Specific examples of the alcohol solvent include butanol.

[0073] Specific examples of the glycol ether-based solvent include ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, and propylene glycol monopropyl ether.

[0074] Specific examples of the glycol ester-based solvent include 1-methoxypropyl-2-acetate.

[0075] Two or more other solvents may be used in combination.

[0076] The content of other solvents is preferably 9.5 to 69.5% by mass, more preferably 30 to 65% by mass, and even more preferably 40 to 60% by mass, based on the total mass of the present composition.

[0077] The total amount of cyclohexanone and other solvents is 10% by mass or more, preferably 30% by mass or more, and more preferably 40% by mass or more, based on the total mass of the present composition, from the viewpoint of further suppressing water content in the present composition.

[0078] From the viewpoint of transportability and storage properties of the present composition, the total amount of cyclohexanone and other solvents is preferably 70% by mass or less, more preferably 65% ​​by mass or less, and even more preferably 60% by mass or less, based on the total mass of the present composition.

[0079] The method for producing the present composition is not particularly limited, and for example, a method of using a solution containing a fluorinated polymer and a polymerization solvent for the fluorinated polymer and adjusting the contents of cyclohexanone and other solvents to be within the above ranges can be cited. The polymerization solvent may contain at least one of cyclohexanone and other solvents.

[0080] Furthermore, as another embodiment of the method for producing the present composition, there is mentioned a method of mixing a fluorinated polymer, cyclohexanone and another solvent.

[0081] The present coating comprises the above-mentioned present composition and a coating solvent.

[0082] The content of the present composition in the present coating material may be appropriately set so that the content of the fluorinated polymer in the present coating material becomes 5 to 70% by mass based on the total mass of the present coating material.

[0083] Specific examples of the coating solvent are the same as the specific examples of the other solvents contained in the present composition. The coating solvent and the other solvents contained in the present composition may be the same as or different from each other.

[0084] The coating solvents may be used in combination of two or more.

[0085] The content of the coating solvent may be appropriately set so that the content of the fluorinated polymer in the coating material falls within the above range.

[0086] The present coating material may contain components other than those mentioned above. Examples of such components include additives.

[0087] Examples of the additives include curing agents, curing catalysts, resins other than the above-mentioned fluorinated polymers (such as (meth) acrylic resins, urethane resins, and epoxy resins), colorants (dyes, organic pigments, inorganic pigments, bright pigments using metals or mica, etc.), ultraviolet absorbers, matting agents, leveling agents, surface conditioners, degassing agents, fillers, thickeners, dispersants, surfactants, antistatic agents, rust inhibitors, silane coupling agents, antifouling agents, antifouling treatment agents, plasticizers, adhesives, and the like.

[0088] The substrate with a coating film of the present invention comprises a substrate and the present coating film disposed on the substrate.

[0089] Specific examples of the material of the substrate include inorganic substances, organic substances, and organic-inorganic composite materials.

[0090] Specific examples of the inorganic substance include concrete, natural stone, glass, and metals (iron, stainless steel, aluminum, aluminum alloy, copper, brass, titanium, etc.).

[0091] Specific examples of organic substances include plastics, rubber, adhesives, and wood.

[0092] Specific examples of the organic-inorganic composite material include fiber-reinforced plastics, resin-reinforced concrete, and fiber-reinforced concrete.

[0093] The substrate may be subjected to a known surface treatment (chemical conversion treatment, etc.) The substrate may also have a resin layer (polyester resin layer, acrylic resin layer, silicone resin layer, etc.) formed by applying a primer, etc., on its surface.

[0094] From the viewpoint of providing a substrate with the present coating film with more excellent weather resistance, the film thickness of the present coating film is preferably 1 to 200 μm, more preferably 10 to 100 μm.

[0095] The method for producing the substrate with the present coating film is a method of applying the present coating material on the substrate to form the present coating film. The present coating film can be formed by applying the present coating material on the substrate and then drying and heating and curing it as needed.

[0096] This coating can be directly applied to the surface of the substrate, or it can be applied after the surface of the substrate is subjected to a known surface treatment (substrate treatment, etc.). Furthermore, it can also be applied to the primer layer after forming a primer layer on the substrate. In addition, this coating can be applied to an article having the above-mentioned substrate.

[0097] Examples of the coating method include spray coating, blade coating, flow coating, bar coating, spin coating, dip coating, screen printing, gravure printing, die coating, inkjet, curtain coating, and methods using a brush or a doctor blade.

[0098] In the method for producing the substrate with the present coating film, it is preferred to include a treatment for removing the solvent by drying after coating. The drying temperature is usually 0 to 50° C., and the drying time is usually 1 minute to 2 weeks.

[0099] When the coating material contains a curing agent, it is preferably cured by heating after application. The curing temperature is usually 50 to 300° C., and the curing time is usually 1 minute to 24 hours.

[0100] Example

[0101] The present invention is described in detail below with examples. Examples 1 to 5 are embodiments, and Examples 6 to 8 are comparative examples. However, the present invention is not limited to these examples.

[0102] [Example 1]

[0103] Into a stainless steel pressure-resistant reactor with an internal volume of 2500 mL equipped with a stirrer, 8.6 g of a piperidyl-containing compound (manufactured by BASF, trade name "TINUVIN 292", a mixture of bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and methyl 1,2,2,6,6-pentamethyl-4-piperidyl sebacate (mass ratio 3:1)), 5.7 g of hydrotalcite (manufactured by Kyowa Chemical Industry Co., Ltd., trade name "KW500", particle size 45 μm or less: 38 %, 45~75μm: 35%, 75~106μm: 21%, 106~500μm: 6%), cyclohexanone, xylene 850g, ethyl vinyl ether (hereinafter, also referred to as EVE) 196g, 4-hydroxybutyl vinyl ether (hereinafter, also referred to as HBVE) 123g, cyclohexyl vinyl ether (hereinafter, also referred to as CHVE) 198g and t-butyl peroxypivalate (hereinafter, also referred to as PBPV) 10g, and the dissolved oxygen in the liquid was removed by pressurization / purging with nitrogen and degassing. It should be noted that the amount of cyclohexanone added was appropriately adjusted so that the content of cyclohexanone in the obtained fluorinated polymer composition 1 became the value described in Table 1.

[0104] Next, 629 g of chlorotrifluoroethylene (hereinafter also referred to as CTFE) was introduced, and the temperature was slowly raised while the reaction was continued at 65° C. After 12 hours, the reactor was water-cooled to stop the reaction. After the reaction solution was cooled to room temperature, unreacted monomers were purged and the reactor was opened.

[0105] The obtained reaction solution was transferred to a pressure filter equipped with filter paper No. 63 for viscous liquid, and after filtering out the hydrotalcite at a pressure of 0.05 MPa, at least a portion of the solvent in the reaction solution was distilled off under reduced pressure heating at 85° C. and 55 Torr using a vacuum distillation apparatus to obtain a solution containing a fluorinated polymer.

[0106] Then, xylene was added to the solution containing the fluorinated polymer to adjust the concentration, thereby obtaining a fluorinated polymer composition 1.

[0107] [Example 2]

[0108] Cyclohexanone, 587 g of xylene, 168 g of ethanol, 206 g of EVE, 129 g of HBVE, 208 g of CHVE, 11 g of potassium carbonate, and 3.5 g of PBPV were placed in a stainless steel pressure-resistant reactor with an internal volume of 2500 mL and equipped with a stirrer, and the dissolved oxygen in the liquid was removed by pressurization / purging with nitrogen and degassing. It should be noted that the amount of cyclohexanone added was appropriately adjusted so that the content of cyclohexanone in the obtained fluorinated polymer composition 2 became the value described in Table 1.

[0109] Next, 660 g of CTFE was introduced, and the temperature was slowly raised while the reaction was continued while being maintained at 65° C. After 12 hours, the reactor was water-cooled to stop the reaction. After the reaction liquid was cooled to room temperature, the unreacted monomers were purged and the reactor was opened.

[0110] The obtained reaction solution was transferred to a pressure filter equipped with filter paper No. 63 for viscous liquid, and after potassium carbonate was filtered out at a pressure of 0.05 MPa, 0.1 g of hydroquinone monomethyl ether (hereinafter referred to as HQMME) was added. Next, at least a portion of the solvent in the reaction solution was distilled off under reduced pressure heating at 85°C and 55 Torr using a vacuum distillation apparatus. Next, 0.06 g / cm2 of ... 2 The mixture was mixed with diatomaceous earth (median particle size 30.1 μm), and then transferred to a pressure filter equipped with filter paper No. 63 for viscous liquid, and filtered twice at a pressure of 0.02 MPa to filter out the diatomaceous earth, thereby obtaining a solution containing a fluorine-containing polymer.

[0111] Then, xylene was added to the solution containing the fluorinated polymer to adjust the concentration, thereby obtaining a fluorinated polymer composition 2.

[0112] [Example 3]

[0113] Into a stainless steel pressure-resistant reactor with an internal volume of 2500 mL equipped with a stirrer, 5.5 g of a piperidinyl-containing compound (manufactured by BASF, trade name "TINUVIN292"), 5.5 g of hydrotalcite (manufactured by Kyowa Chemical Industry Co., Ltd., trade name "KW500"), cyclohexanone, 841 g of xylene, 92 g of HBVE, 289 g of CHVE, 206 g of 2-ethylhexyl vinyl ether (hereinafter also referred to as 2EHVE), and 8.5 g of PBPV were charged, and the dissolved oxygen in the liquid was removed by pressurization / purging with nitrogen and degassing. It should be noted that the amount of cyclohexanone added was appropriately adjusted so that the content of cyclohexanone in the obtained fluorinated polymer composition 3 became the value described in Table 1.

[0114] Next, 512 g of CTFE was introduced, and the temperature was slowly raised while the reaction was continued while being maintained at 65° C. After 12 hours, the reactor was water-cooled to stop the reaction. After the reaction liquid was cooled to room temperature, the unreacted monomers were purged and the reactor was opened.

[0115] The obtained reaction solution was transferred to a pressure filter equipped with filter paper No. 63 for viscous liquid, and after filtering out the hydrotalcite at a pressure of 0.05 MPa, at least a portion of the solvent in the reaction solution was distilled off under reduced pressure heating at 85° C. and 55 Torr using a vacuum distillation apparatus to obtain a solution containing a fluorinated polymer.

[0116] Then, xylene was added to the solution containing the fluorinated polymer to adjust the concentration, thereby obtaining a fluorinated polymer composition 3.

[0117] [Example 4]

[0118] Into a stainless steel pressure-resistant reactor with an internal volume of 2500 mL equipped with a stirrer, 20 g of a piperidinyl-containing compound (manufactured by BASF, trade name "TINUVIN 292"), 20 g of hydrotalcite (manufactured by Kyowa Chemical Industry Co., Ltd., trade name "KW500"), cyclohexanone, 679 g of xylene, 118 g of HBVE, and 453 g of CHVE were charged, and the dissolved oxygen in the liquid was removed by degassing with nitrogen. It should be noted that the amount of cyclohexanone added was appropriately adjusted so that the content of cyclohexanone in the obtained fluorinated polymer composition 4 became the value described in Table 1.

[0119] Furthermore, 536 g of CTFE was introduced into the reactor and then the temperature was raised. The pressure when the temperature in the reactor reached 65° C. was 0.59 MPaG. Then, 2 ml of a 5% xylene solution of PBPV was added into the reactor to start the reaction.

[0120] As the pressure decreases, while maintaining the pressure, monomers CTFE 110g, CHVE 93g and HBVE 24g are continuously added to the reactor, and PBPV 5% xylene solution as a free radical polymerization initiator is added to the reactor one by one to polymerize. After the polymerization starts, the total amount of PBPV 5% xylene solution added to the reactor is 55ml. After 16 hours, the reactor is water-cooled to stop the reaction. After the reaction solution is cooled to room temperature, the unreacted monomers are purged and the reactor is opened.

[0121] The obtained reaction solution was transferred to a pressure filter equipped with filter paper No. 63 for viscous liquid, and after filtering out the hydrotalcite at a pressure of 0.05 MPa, at least a portion of the solvent in the reaction solution was distilled off under reduced pressure heating at 85° C. and 55 Torr using a vacuum distillation apparatus to obtain a solution containing a fluorinated polymer.

[0122] Then, xylene was added to the solution containing the fluorine-containing polymer to adjust the concentration, thereby obtaining a fluorine-containing polymer composition 4.

[0123] [Example 5]

[0124] Cyclohexanone, 674 g of xylene, 190 g of ethanol, 308 g of EVE, 124 g of HBVE, 9.5 g of potassium carbonate and 0.6 g of PBPV were placed in a stainless steel pressure-resistant reactor with an internal volume of 2500 mL and equipped with a stirrer, and the dissolved oxygen in the liquid was removed by pressurization / purging with nitrogen and degassing. It should be noted that the amount of cyclohexanone added was appropriately adjusted so that the content of cyclohexanone in the obtained fluorinated polymer composition 5 became the value described in Table 1.

[0125] Next, 622 g of CTFE was introduced, and the temperature was slowly raised while the reaction was continued while being maintained at 65° C. After 12 hours, the reactor was water-cooled to stop the reaction. After the reaction liquid was cooled to room temperature, the unreacted monomers were purged and the reactor was opened.

[0126] The obtained reaction solution was transferred to a pressure filter equipped with filter paper No. 63 for viscous liquid, and after potassium carbonate was filtered out at a pressure of 0.05 MPa, 0.1 g of hydroquinone monomethyl ether (hereinafter referred to as HQMME) was added. Next, at least a portion of the solvent in the reaction solution was distilled off under reduced pressure heating at 85°C and 55 Torr using a vacuum distillation apparatus. Next, 0.06 g / cm2 of ... 2 The mixture was mixed with diatomaceous earth (median particle size 30.1 μm), and then transferred to a pressure filter equipped with filter paper No. 63 for viscous liquid, and filtered twice at a pressure of 0.02 MPa to filter out the diatomaceous earth, thereby obtaining a solution containing a fluorine-containing polymer.

[0127] Then, xylene was added to the solution containing the fluorine-containing polymer to adjust the concentration, thereby obtaining a fluorine-containing polymer composition 5.

[0128] [Example 6]

[0129] Cyclohexanone, 587 g of xylene, 168 g of ethanol, 206 g of EVE, 129 g of HBVE, 208 g of CHVE, 11 g of potassium carbonate and 3.5 g of PBPV were placed in a stainless steel pressure-resistant reactor with an internal volume of 2500 mL and equipped with a stirrer, and dissolved oxygen in the liquid was removed by pressurization / purging with nitrogen and degassing. It should be noted that the amount of cyclohexanone added was appropriately adjusted so that the content of cyclohexanone in the obtained fluorinated polymer composition 6 became the value described in Table 1.

[0130] Next, 660 g of CTFE was introduced, and the temperature was slowly raised while the reaction was continued while being maintained at 65° C. After 12 hours, the reactor was water-cooled to stop the reaction. After the reaction liquid was cooled to room temperature, the unreacted monomers were purged and the reactor was opened.

[0131] The obtained reaction solution was transferred to a pressure filter equipped with filter paper No. 63 for viscous liquid, and after potassium carbonate was filtered out at a pressure of 0.05 MPa, 0.1 g of hydroquinone monomethyl ether (hereinafter referred to as HQMME) was added. Next, at least a portion of the solvent in the reaction solution was distilled off under reduced pressure heating at 65°C and 45 Torr using a vacuum distillation apparatus. Next, 0.06 g / cm2 of ... 2 The mixture was mixed with diatomaceous earth (median particle size 30.1 μm), and then transferred to a pressure filter equipped with filter paper No. 63 for viscous liquid, and filtered twice at a pressure of 0.02 MPa to filter out the diatomaceous earth, thereby obtaining a solution containing a fluorine-containing polymer.

[0132] Then, xylene was added to the solution containing the fluorine-containing polymer to adjust the concentration, thereby obtaining a fluorine-containing polymer composition 6.

[0133] [Example 7]

[0134] Cyclohexanone, 587 g of xylene, 168 g of ethanol, 206 g of EVE, 129 g of HBVE, 208 g of CHVE, 11 g of potassium carbonate, and 3.5 g of PBPV were placed in a stainless steel pressure-resistant reactor with an internal volume of 2500 mL and equipped with a stirrer, and the dissolved oxygen in the liquid was removed by pressurization / purging with nitrogen and degassing. It should be noted that the amount of cyclohexanone added was appropriately adjusted so that the content of cyclohexanone in the obtained fluorinated polymer composition 7 became the value described in Table 1.

[0135] Next, 660 g of CTFE was introduced, and the temperature was slowly raised while the reaction was continued while being maintained at 65° C. After 12 hours, the reactor was water-cooled to stop the reaction. After the reaction liquid was cooled to room temperature, the unreacted monomers were purged and the reactor was opened.

[0136] The obtained reaction solution was transferred to a pressure filter equipped with filter paper No. 63 for viscous liquid, and after potassium carbonate was filtered out at a pressure of 0.05 MPa, 0.1 g of hydroquinone monomethyl ether (hereinafter referred to as HQMME) was added. Next, at least a portion of the solvent in the reaction solution was distilled off under reduced pressure heating at 65°C and 15 Torr using a vacuum distillation apparatus. Next, 0.06 g / cm2 of ... 2 The mixture was mixed with diatomaceous earth (median particle size 30.1 μm), and then transferred to a pressure filter equipped with filter paper No. 63 for viscous liquid, and filtered twice at a pressure of 0.02 MPa to filter out the diatomaceous earth, thereby obtaining a solution containing a fluorine-containing polymer.

[0137] Then, xylene was added to the solution containing the fluorine-containing polymer to adjust the concentration, thereby obtaining a fluorine-containing polymer composition 7.

[0138] [Example 8]

[0139] Using the fluorinated polymer composition 2 of Example 2, volatile components were removed by heating at 65°C under reduced pressure for 3 hours in a vacuum dryer, and then removed by heating at 130°C under reduced pressure for 20 minutes to obtain a solid fluorinated polymer composition 8.

[0140] [Colorability after storage]

[0141] About the fluorinated polymer composition of each example, the difference in coloration before and after storage in a thermostatic bath at 70°C for 2 weeks was evaluated according to the following criteria.

[0142] A: No color difference before and after storage.

[0143] B: Visually, there is a color difference before and after storage

[0144] [Water content]

[0145] The water content of the fluoropolymer composition of each example immediately after production was measured by Karl Fischer coulometric titration using a Karl Fischer moisture meter (MKH-710 manufactured by Kyoto Electronics Co., Ltd.), and the water content was evaluated according to the following criteria.

[0146] The fluorinated polymer compositions of Examples 1 to 7 were subjected to Karl Fischer coulometric titration using a direct titration method, and the fluorinated polymer composition of Example 8 was subjected to Karl Fischer coulometric titration using a water vaporization method.

[0147] A: Water content is 1000 ppm by mass or less

[0148] B: Moisture content exceeds 1000 ppm by mass

[0149] [Leveling]

[0150] 10 parts by mass of the fluoropolymer in the fluoropolymer composition of each example, 40 parts by mass of titanium oxide (Ti-Pure (registered trademark) R960 manufactured by DuPont) and xylene in an amount such that the total amount of the fluoropolymer and the titanium oxide is 50% by mass of the total amount were mixed and stirred for 1 hour using a rocking mill to prepare a mill base.

[0151] Next, 37 parts by mass of the obtained grinding base, 30 parts by mass of the fluoropolymer in the fluoropolymer composition of each example, 2 parts by mass of 1 / 10000 diluted DBTDL and an amount of xylene in which the total amount of the fluoropolymer and the amount of titanium oxide is 50% by mass of the total amount are mixed, and stirred again for 30 minutes using a rocking mill to prepare a main agent.

[0152] Next, 100 parts by mass of the main agent and an isocyanate curing agent (Desmodur (registered trademark) N3300 manufactured by Bayer AG) (6.1 parts by mass in Examples 1, 2, 6, 7 and 8, 4.7 parts by mass in Example 3, 5.4 parts by mass in Example 4 and 6.7 parts by mass in Example 5) were mixed to prepare a coating corresponding to each example.

[0153] <Production of coated substrate>

[0154] The obtained coating was applied to one side of an aluminum plate treated with chromate using an applicator, and then kept in an atmosphere at 80° C. for 1 hour. After heating, the aluminum plate with a coating layer corresponding to each example was placed and cooled to room temperature (23° C.) to obtain an aluminum plate with a coating film (cured film) having a film thickness of 40 μm.

[0155] <Evaluation of coating film leveling>

[0156] 24 hours after the production of the aluminum plate with a coating film, the leveling property of the coating film was evaluated according to the following criteria.

[0157] A: No ripples or patterns can be visually confirmed on the coating surface

[0158] B: Fluctuations and patterns are visually observed on the coating surface

[0159] [Table 1]

[0160]

[0161] As shown in Table 1, it was confirmed that the fluorinated polymer composition of the present invention suppressed coloration after water inclusion and storage, and when mixed with a coating solvent to produce a coating, a coating film formed using the coating had excellent leveling properties (Examples 1 to 5).

[0162] It should be noted that the entire contents of the specification, claims, and abstract of Japanese Patent Application No. 2022-157420 filed on September 30, 2022 are cited herein and incorporated as a disclosure of the specification of the present invention.

Claims

1. A fluorine-containing polymer composition for coating, comprising a fluorine-containing polymer, cyclohexanone, and a solvent different from the cyclohexanone, wherein the fluorine-containing polymer comprises a unit based on a fluoroolefin and a unit based on a monomer having no fluorine atom, The total amount of the cyclohexanone and the solvent is 10% by mass or more based on the total mass of the fluorinated polymer composition for coating, The content of the cyclohexanone is 0.5 to 2.0 mass % based on the total mass of the fluorinated polymer composition for coating.

2. The fluorinated polymer composition for coating according to claim 1, wherein The fluoroolefin is CF2=CFCl.

3. The fluorinated polymer composition for coating according to claim 1 or 2, wherein The unit based on a monomer having no fluorine atom includes at least one of a unit based on a monomer having no fluorine atom and no reactive group and a unit based on a monomer having a reactive group and having no fluorine atom.

4. The fluorinated polymer composition for coating according to claim 3, wherein The reactive group is a hydroxyl group.

5. The fluorinated polymer composition for coating according to claim 1 or 2, wherein The total amount of the cyclohexanone and the solvent is 70% by mass or less based on the total mass of the fluorinated polymer composition for coating material.

6. The fluorinated polymer composition for coating according to claim 1 or 2, wherein The total amount of the cyclohexanone and the solvent is 30% by mass or more based on the total mass of the fluorinated polymer composition for coating material.

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