TW202419484A - Fluorinated polymer composition for painting materials - Google Patents

Abstract

Provided is a fluorinated polymer composition for painting materials, which is prevented from discoloration after the bearing of water and storage, and, when a painting material is produced by mixing the fluorinated polymer composition with a solvent for painting materials, a coating film formed using the painting material has excellent levering properties. The fluorinated polymer composition for painting materials according to the present invention comprises a fluorinated polymer containing a unit derived from a fluoroolefin and a unit derived from a monomer having no fluorine atom, cyclohexanone, and a solvent that is different from cyclohexanone, in which the total amount of cyclohexanone and the solvent is 10% by mass or more relative to the whole mass of the fluorinated polymer composition for painting materials and the content of cyclohexanone is 0.5 to 2.0% by mass relative to the whole mass of the fluorinated polymer composition for painting materials.

Description

Fluoropolymer composition for coating

The present invention relates to a fluorine-containing polymer composition for coating.

Fluoropolymer-containing coatings are used in various fields because they can form coating films with excellent weather resistance. Patent document 1 shows that a composition containing a fluorine-containing polymer and butyl acetate as a solvent is used as a coating, and the fluorine-containing polymer contains a fully halogenated olefin unit, a vinyl ester unit containing neither a hydroxyl group nor an aromatic ring, and a hydroxyl-containing monomer unit. Prior art document Patent document

Patent Document 1: International Publication No. 2017/155022

[The problem the invention is trying to solve]

In recent years, there has been a demand for further improvement in the leveling property of coatings obtained using coatings containing fluorine-containing polymers. The inventors of the present invention evaluated coatings formed using coatings such as those described in Patent Document 1 and found that there is room for improvement in the leveling property. In addition, coatings containing fluorine-containing polymers are sometimes produced by further adding a coating solvent to a fluorine-containing polymer composition for coating containing a fluorine-containing polymer and a small amount of solvent in a manner that has a viscosity suitable for coating. Such fluorine-containing polymer compositions for coatings are sometimes stored for a long time before the coating is manufactured. Therefore, a fluorine-containing polymer composition for coatings in which coloring after storage is suppressed is sought. In addition, since this may sometimes cause the coating to become cloudy, the fluorinated polymer composition used in the coating is required to be less likely to absorb moisture.

The present invention is made in view of the above problems, and its subject is to provide a fluorine-containing polymer composition for coating, which suppresses coloring after water inclusion and storage, and when mixed with a coating solvent to produce a coating, the coating film formed by using the coating has excellent leveling properties. [Technical means for solving the problem]

The inventors of the present invention have conducted intensive research and found that the above-mentioned problems can be solved by the following composition. [1] A fluorine-containing polymer composition for coating, comprising: a fluorine-containing polymer containing units based on fluoroolefins and units based on monomers not having fluorine atoms; cyclohexanone; and a solvent different from the cyclohexanone; wherein the total amount of the cyclohexanone and the solvent is 10% by mass or more relative to the total mass of the fluorine-containing 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 fluorine-containing polymer composition for coating. [2] A fluorine-containing polymer composition for coating as described in [1], wherein the fluorine-containing olefin is _CF2 =CFCl. [3] The fluorinated polymer composition for coating as described in [1] or [2], wherein the units based on monomers not having fluorine atoms include at least one of units based on monomers not having fluorine atoms and reactive groups and units based on monomers having reactive groups and not having fluorine atoms. [4] The fluorinated polymer composition for coating as described in [3], wherein the reactive groups are hydroxyl groups. [5] The fluorinated polymer composition for coating as described in any one of [1] to [4], wherein the total amount of the cyclohexanone and the solvent is 70% by mass or less relative to the total mass of the fluorinated polymer composition for coating. [6] The fluorinated polymer composition for coating as described in any one of [1] to [5], wherein the total amount of the cyclohexanone and the solvent is 30% by mass or more relative to the total mass of the fluorinated polymer composition for coating. [Effects of the Invention]

According to the present invention, a fluorine-containing polymer composition for coating can be provided, which suppresses coloration after water inclusion and storage, and when mixed with a coating solvent to produce a coating, the coating film formed using the coating has excellent leveling properties.

The meanings of the terms used in the present invention are as follows. The range of numerical values represented by "～" means a range including the numerical values written before and after "～" as the lower limit and the upper limit. A unit is a general term for an atomic group based on one molecule of the above monomer formed directly by polymerization of the monomer, and an atomic group obtained by chemically converting a part of the above atomic group. The content (mol %) of each unit contained in the polymer relative to all units is obtained by analyzing the polymer by nuclear magnetic resonance spectroscopy, and can also be determined based on the amount of components added when the polymer is manufactured. "(Meth) acrylic acid" is a general term for "acrylic acid" and "methacrylic acid", and "(meth) acrylate" is a general term for "acrylate" and "methacrylate". A hydrolyzable silyl group means a group that can undergo a hydrolysis reaction to form a silanol group. The acid value and hydroxyl value are values measured according to the method of JIS K 0070-3 (1992). The glass transition temperature (Tg) is the midpoint glass transition temperature of the polymer measured by differential scanning calorimetry (DSC). The number average molecular weight (Mn) is a value measured by gel permeation chromatography using polystyrene as a standard substance.

The fluorine-containing polymer composition for coating of the present invention (hereinafter also referred to as the present composition) comprises: a fluorine-containing polymer containing a unit based on a fluoroolefin and a unit based on a monomer having no fluorine atoms; cyclohexanone; and a solvent different from the above cyclohexanone (hereinafter also referred to as other solvents). In addition, the total amount of the above cyclohexanone and the above other solvents is 10% by mass or more relative to the total mass of the present composition. In addition, the content of the above cyclohexanone is 0.5 to 2.0% by mass relative to the total mass of the present composition. The present composition can suppress coloring after storage. Although the reason is not necessarily clear, it is presumed that the content of cyclohexanone in the present composition is 2.0 mass % or less, which can inhibit the generation of compounds that cause coloration over time, such as dimers of cyclohexanone or chelates of metal components (e.g., potassium ions from potassium carbonate used in production) and cyclohexanone that may be contained in the composition. In addition, the present composition inhibits water inclusion. Although the reason is not necessarily clear, it is presumed that the total amount of cyclohexanone and other solvents in the present composition is 10 mass % or more, so that it is not easy to introduce water into the system. In addition, the coating film (hereinafter also referred to as the present coating film) formed using the coating (hereinafter also referred to as the present coating) containing the present composition and the coating solvent is excellent in leveling properties. Although the reason is not necessarily clear, it is presumed that the content of cyclohexanone in the composition is 0.5 mass% or more, so that the function of cyclohexanone, which has excellent compatibility with the fluorine-containing polymer, is well exerted, and the fluorine-containing polymer is well dissolved in the coating, resulting in the improvement of the leveling property of the coating (i.e., the smoothness of the coating).

The fluorine-containing polymer includes 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).

Fluoroolefins are alkenes in which one or more hydrogen atoms are replaced by fluorine atoms. In fluoroolefins, one or more hydrogen atoms not replaced by fluorine atoms may be replaced by chlorine atoms. The carbon number of the fluoroolefin is preferably 2 to 6, more preferably 2 to 4. Examples of the fluoroolefin include _CF2 = _CF2 , _CF2 =CFCl, _CF2 =CHF, _CH2 = _CF2 , _CF2 = _CFCF3 , _CF3 -CH=CHF, _CF3 -CF= _CH2 , etc. In terms of weather resistance and polymerizability with monomers other than fluoroolefins, the fluoroolefin is preferably _CF2 = _CF2 or _CF2 =CFCl, more preferably _CF2 =CFCl.

Two or more fluoroolefins may be used in combination. In terms of weather resistance of the present coating, the content of unit F is preferably 20 to 70 mol%, more preferably 30 to 60 mol%, and even more preferably 45 to 55 mol%, relative to all units contained in the fluorine-containing polymer.

Unit A is preferably a unit (hereinafter referred to as unit A1) based on a monomer having no fluorine atom and a reactive group (hereinafter referred to as monomer a1) and a unit (hereinafter referred to as unit A2) based on a monomer having a reactive group and having no fluorine atom (hereinafter referred to as monomer a2). Specific examples of the reactive group include: a hydroxyl group, an amino group, an epoxy group, an oxocyclobutyl group, a hydrolyzable silyl group, a sulfo group, and a carboxyl group. The sulfo group and the carboxyl group may be ionized to form -SO ₃ ^- or -COO ^- , or may be chlorinated to form -SO ₃ ^- Na ⁺ or -COO ^- Na ⁺ , etc.

The monomer a1 preferably comprises at least one selected from the group consisting of vinyl ether, vinyl ester, allyl ether, allyl ester, and (meth)acrylate, and more preferably one or both of vinyl ether and vinyl ester in terms of copolymerizability with fluoroolefin and weather resistance of the fluorinated polymer.

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 (a product of HEXION called VeoVa9), vinyl neodecanoate (a product of HEXION called VeoVa10), vinyl benzoate, vinyl benzoate, tert-butyl (meth)acrylate, and benzyl (meth)acrylate. Two or more monomers a1 may be used in combination.

When the fluorine-containing polymer includes the unit A1, the content of the unit A1 is preferably 5 to 60 mol %, more preferably 10 to 50 mol %, relative to all units contained in the fluorine-containing polymer.

When the fluorine-containing polymer includes unit A2, the fluorine-containing polymer may have a part or all of the reactive groups in unit A2 when reacting with other components (e.g., a hardener, etc.), or may have a part or all of the reactive groups in unit A2 when not reacting with other components, preferably having a part or all of the reactive groups in unit A2 when not reacting with other components. That is, the fluorine-containing polymer in the present composition may exist in a state of having a cross-linked structure formed by a hardener, or may exist in a state of not having a cross-linked structure.

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. Examples of such a unit include a unit obtained by reacting a polycarboxylic acid or an anhydride thereof with a fluoropolymer containing a unit having a hydroxyl group, and converting a part or all of the hydroxyl groups into carboxyl groups.

Unit A2 preferably has a hydroxyl group or a carboxyl group as a reactive group, and more preferably has a hydroxyl group. Examples of monomer a2 having a hydroxyl group include vinyl ether, vinyl ester, allyl ether, allyl ester or (meth)acrylate, or allyl alcohol, etc. having a hydroxyl group. As monomer a2 having a hydroxyl group, hydroxy vinyl ether or hydroxy allyl ether is preferred.

The monomer a2 having a hydroxyl group is preferably a monomer represented by the formula ^X1 - ^Z1 . ^X1 is _CH2 =CHC(O)O-, _CH2 =C( _CH3 )C(O)O-, _CH2 =CHOC(O)-, _CH2 = _CHCH2OC (O)-, _CH2 =CHO- or _CH2 = _CHCH2O- , preferably _CH2 =CHO- or _CH2 = _CHCH2O- . ^Z1 is a monovalent organic group having 2 to 42 carbon atoms and having a hydroxyl group. The organic group may be a straight chain or a branched chain. In addition, the organic group may be composed of a ring structure or may contain a ring structure. The organic group is preferably 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.

Specific examples of the monomer a2 having a hydroxyl group include _CH2 = _CHO - _{CH2 - cycloC6H10 - CH2OH} , CH2 _{= CHCH2O} - _CH2 - _{cycloC6H10 - CH2OH , CH2 =} CHO _- CH2- _{cycloC6H10 -CH2-} ( _OCH2CH2 ) _15OH , _{CH2 = CHOCH2CH2OH , CH2 = CHCH2OCH2CH2OH} , _{CH2 = CHOCH2CH2CH2CH2OH} , and CH2= _{CHCH2OCH2CH2CH2CH2OH} . _{" -cycloC6H10-} " represents _{a cyclohexyl} group, _and the bonding site of " _{-cycloC6H10- " is} usually _1,4- .

Examples of the monomer a2 having a carboxyl group include monomers obtained by reacting carboxylic anhydride with an unsaturated carboxylic acid, (meth)acrylic acid, and a hydroxyl group of a monomer having a hydroxyl group. Specific examples of the monomer a2 having a carboxyl group include monomers represented by _CH2 =CHCOOH, CH( _CH3 )=CHCOOH, _CH2 =C( _CH3 )COOH, HOOCCH=CHCOOH, _CH2 =CH( _CH2 ) _n11COOH (where n11 represents an integer of 1 to 10), and _CH2 =CHO( _CH2 ) _n12OC (O) _CH2CH2COOH (where n12 represents an integer of 1 to ₁₀ ).

Two or more monomers a2 may be used in combination. When the fluorine-containing polymer contains the unit A2, the content of the unit A2 is preferably 0.1 to 45 mol%, more preferably 1 to 35 mol%, and further preferably 5 to 25 mol%, relative to all the units contained in the fluorine-containing polymer.

The fluorine-containing polymer is preferably a copolymer containing 20-70 mol% of unit F, 5-60 mol% of unit A1 and 0.1-45 mol% of unit A2 in sequence relative to all units contained in the fluorine-containing polymer, and more preferably a copolymer containing 30-60 mol% of unit F, 10-50 mol% of unit A1 and 1-35 mol% of unit A2. Moreover, the fluorine-containing polymer is further preferably composed of unit F, unit A1 and unit A2.

In terms of the hardness of the coating, the Tg of the fluorine-containing polymer is preferably 0 to 120°C, more preferably 10 to 70°C. In terms of the weather resistance of the coating, the Mn of the fluorine-containing polymer is preferably 1,000 to 200,000, more preferably 5,000 to 100,000, and further preferably 8,000 to 50,000.

When the fluoropolymer has a hydroxyl value, the hydroxyl value of the fluoropolymer is preferably 1 to 200 mgKOH/g, more preferably 5 to 100 mgKOH/g, and further preferably 40 to 60 mgKOH/g in terms of durability of the coating. When the fluoropolymer has an acid value, the acid value of the fluoropolymer is preferably 1 to 30 mgKOH/g, and more preferably 1 to 10 mgKOH/g in terms of pigment dispersibility.

As the production method of fluorinated polymers, there are solution polymerization, emulsion polymerization, suspension polymerization, etc., and in terms of water resistance, solution polymerization is preferred. Therefore, fluorinated polymers are preferably produced by polymerizing each monomer in the presence of a polymerization solvent. During the polymerization, polymerization initiators, chain transfer agents, stabilizers, acid acceptors, etc. may also be added as needed.

The content of cyclohexanone is 0.5-2.0% by mass relative to the total mass of the present composition. In terms of the better leveling property of the present coating, it is preferably 0.7% by mass or more, and more preferably 1.0% by mass or more. In terms of being able to further suppress the coloring of the present composition after storage, it is preferably 1.8% by mass or less, and more preferably 1.5% by mass or less. Cyclohexanone can also be used as a polymerization solvent for the manufacture of fluorinated polymers.

The other solvent contained in the present composition is a solvent different from cyclohexanone. The other solvent may be a polymerization solvent used to produce a fluorine-containing polymer. As other solvents, ketone solvents (except cyclohexanone), ester solvents, hydrocarbon solvents, alcohol solvents, glycol ether solvents, and glycol ester solvents can be cited. As specific examples of ketone solvents, acetone, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, and diacetone alcohol can be cited. As specific examples of ester solvents, ethyl acetate and butyl acetate can be cited. As specific examples of hydrocarbon solvents, hexane, heptane, cyclohexane, and xylene can be cited. As a specific example of an alcohol-based solvent, butanol can be cited. As a specific example of a glycol ether-based solvent, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, and propylene glycol monopropyl ether can be cited. As a specific example of a glycol ester-based solvent, 2-acetic acid-1-methoxypropyl ester can be cited.

Two or more other solvents may be used in combination. Relative to the total mass of the composition, the content of the other solvents is preferably 9.5-69.5 mass%, more preferably 30-65 mass%, and even more preferably 40-60 mass%.

The total amount of cyclohexanone and other solvents relative to the total mass of the present composition is 10 mass % or more, which can further suppress the water content of the present composition, preferably 30 mass % or more, more preferably 40 mass % or more. In terms of the transportability and storage properties of the present composition, the total amount of cyclohexanone and other solvents relative to the total mass of the present composition is preferably 70 mass % or less, more preferably 65 mass % or less, and further preferably 60 mass % or less.

The method for preparing the present composition is not particularly limited. For example, the following method can be cited: using a solution containing a fluorine-containing polymer and a polymerization solvent of the fluorine-containing polymer, the content of cyclohexanone and other solvents is adjusted in the above range. The polymerization solvent may contain at least one of cyclohexanone and other solvents. In addition, as another aspect of the method for preparing the present composition, a method of mixing a fluorine-containing polymer, cyclohexanone and other solvents can be cited.

The present coating comprises the present composition described above and a coating solvent.

The content of the present composition in the present coating can be appropriately set in such a manner that the content of the fluorine-containing polymer in the present coating is 5 to 70% by mass relative to the total mass of the present coating.

The specific examples of the coating solvent are the same as the specific examples of other solvents contained in the present composition. The coating solvent may be the same as or different from the other solvents contained in the present composition. Two or more coating solvents may be used in combination. The content of the coating solvent may be appropriately set in such a way that the content of the fluorine-containing polymer in the present coating is within the above range.

This coating may also contain ingredients other than the above. Examples of such ingredients include additives. Examples of additives include: hardeners, hardening catalysts, resins other than the above fluorinated polymers ((meth) acrylic resins, polyurethane resins, epoxy resins, etc.), colorants (dyes, organic pigments, inorganic pigments, bright pigments using metal or mica, etc.), ultraviolet absorbers, matting agents, leveling agents, surface conditioners, degassing agents, fillers, thickeners, dispersants, surfactants, antistatic agents, antirust agents, silane coupling agents, antifouling agents, low-pollution treatment agents, plasticizers, adhesives, etc.

The coated substrate of the present invention comprises a substrate and the coating disposed on the substrate.

Specific examples of materials for the substrate include inorganic substances, organic substances, and organic-inorganic composites. Specific examples of inorganic substances include concrete, natural stone, glass, and metals (iron, stainless steel, aluminum, aluminum alloys, copper, brass, titanium, etc.). Specific examples of organic substances include plastics, rubber, adhesives, and wood. Specific examples of organic-inorganic composites include fiber-reinforced plastics, resin-reinforced concrete, and fiber-reinforced concrete. In addition, the substrate may be subjected to a known surface treatment (chemical treatment, etc.). In addition, a resin layer (polyester resin layer, acrylic resin layer, silicone resin layer, etc.) may be formed by applying a primer etc. on the surface of the substrate in advance.

In order to improve the weather resistance of the substrate with the coating, the thickness of the coating is preferably 1 to 200 μm, more preferably 10 to 100 μm.

The manufacturing method of the substrate with coating is a method of forming the coating by applying the coating on the substrate. The coating can be formed by applying the coating on the substrate, drying it as needed, and heating and curing it. The coating can be applied directly to the surface of the substrate, or after the surface of the substrate is subjected to a known surface treatment (base treatment, etc.). Furthermore, after the base coating is formed on the substrate, it can be applied on the base coating. In addition, the coating can also be applied to an article having the above-mentioned substrate.

As coating methods, there can be cited: spray coating, doctor blade coating, flow coating, rod coating, rotary coating, dip coating, screen printing, gravure printing, die nozzle coating, inkjet, curtain coating, methods using a brush or scraper, etc. In the manufacturing method of the substrate with a coating film, it is preferred to have a process of drying after coating to remove the solvent. The drying temperature is usually 0 to 50°C, and the drying time is usually 1 minute to 2 weeks. In the case where the coating contains a hardener, it is preferred to heat and harden after coating. The heat curing temperature is usually 50 to 300°C, and the heat curing time is usually 1 minute to 24 hours. [Example]

Hereinafter, the present invention will be described in detail with reference to 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.

[Example 1] In a 2500 mL stainless steel pressure-resistant reactor equipped with a stirrer, 8.6 g of a piperidinyl-containing compound (manufactured by BASF, trade name "TINUVIN292", a mixture of bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate and 1,2,2,6,6-pentamethyl-4-piperidinyl sebacate methyl ester (mass ratio 3:1)), 5.7 g of magnesium aluminum carbonate (manufactured by Kyowa Chemical Industry Co., Ltd., trade name "KW500", particle size 45 μm or less: 38%, 45 to 75 μm: 35%, 75 to 106 μm: 21%, 106 to 500 μm: 6%), cyclohexanone, 850 g of xylene, 196 g of ethyl vinyl ether (hereinafter also referred to as EVE) were added. g, 4-hydroxybutyl vinyl ether (hereinafter also referred to as HBVE) 123 g, cyclohexyl vinyl ether (hereinafter also referred to as CHVE) 198 g, and tert-butyl peroxypivalate (hereinafter also referred to as PBPV) 10 g, and the dissolved oxygen in the solution was removed by pressurizing, flushing and degassing with nitrogen. Furthermore, the amount of cyclohexanone added was appropriately adjusted in such a way that the content of cyclohexanone in the obtained fluorinated polymer composition 1 became the value recorded in Table 1. Then, 629 g of chlorotrifluoroethylene (hereinafter also referred to as CTFE) was introduced, and the temperature was slowly raised, and the reaction was continued while maintaining the temperature 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 flushed and the reactor was opened. The obtained reaction solution was transferred to a pressure filter equipped with a No. 63 filter paper for viscosity adjustment, and the aluminum magnesium carbonate was separated by filtration at a pressure of 0.05 MPa. Then, at least a portion of the solvent in the reaction solution was distilled off by a reduced pressure distillation device at 85°C and 55 Torr under reduced pressure heating to obtain a solution containing a fluorine-containing polymer. Thereafter, xylene was added to the solution containing the fluorine-containing polymer to adjust the concentration, and a fluorine-containing polymer composition 1 was obtained.

[Example 2] 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 added to a stainless steel pressure-resistant reactor with a content volume of 2500 mL and equipped with a stirrer, and the dissolved oxygen in the solution was removed by pressurizing, flushing, and degassing with nitrogen. The amount of cyclohexanone added was appropriately adjusted in such a way that the content of cyclohexanone in the obtained fluoropolymer composition 2 became the value recorded in Table 1. Then, 660 g of CTFE was introduced, and the temperature was slowly raised, and the reaction was continued while maintaining the temperature at 65°C. After 12 hours, the reactor was water-cooled to stop the reaction. After the reaction liquid is cooled to room temperature, the unreacted monomers are rinsed and the reactor is opened. The obtained reaction liquid is transferred to a pressure filter equipped with a No. 63 filter paper for viscosity adjustment, and potassium carbonate is separated by filtration at a pressure of 0.05 MPa, and then 0.1 g of hydroquinone monomethyl ether (hereinafter referred to as HQMME) is added. Next, at least a portion of the solvent in the reaction liquid is distilled off by a reduced pressure distillation device at 85°C and 55 Torr under reduced pressure heating. Next, diatomaceous earth (median particle size 30.1 μm) with a relative filtering area of 0.06 g/cm ² was added to the reaction solution, mixed and stirred, and then transferred to a pressure filter equipped with a No. 63 filter paper for viscosity adjustment, and a second filtration was performed at a pressure of 0.02 MPa to separate the diatomaceous earth and obtain a solution containing a fluorine-containing polymer. Subsequently, xylene was added to the solution containing the fluorine-containing polymer to adjust the concentration, and a fluorine-containing polymer composition 2 was obtained.

[Example 3] Into a stainless steel pressure-resistant reactor with a capacity of 2500 mL and equipped with a stirrer, 5.5 g of a piperidine-containing compound (manufactured by BASF, trade name "TINUVIN292"), 5.5 g of aluminum magnesium carbonate (manufactured by Kyowa Chemical Industries, 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 added, and the dissolved oxygen in the solution was removed by pressurizing, flushing, and degassing with nitrogen. The amount of cyclohexanone added was appropriately adjusted so that the content of cyclohexanone in the obtained fluorinated polymer composition 3 would be the value described in Table 1. Then, 512 g of CTFE was introduced, and the temperature was slowly raised while the reaction was continued while maintaining the temperature 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 monomer was rinsed and the reactor was opened. The obtained reaction liquid was transferred to a pressure filter equipped with a No. 63 filter paper for viscosity adjustment, and the aluminum magnesium carbonate was filtered and separated at a pressure of 0.05 MPa. Then, at least a part of the solvent in the reaction liquid was distilled off by a reduced pressure distillation device at 85°C and 55 Torr under reduced pressure heating to obtain a solution containing a fluorine-containing polymer. Subsequently, xylene was added to the solution containing the fluorine-containing polymer to adjust the concentration, thereby obtaining the fluorine-containing polymer composition 3.

[Example 4] In a stainless steel pressure-resistant reactor with a capacity of 2500 mL and equipped with a stirrer, 20 g of a piperidine-containing compound (manufactured by BASF, trade name "TINUVIN292"), 20 g of aluminum magnesium carbonate (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 added, and the dissolved oxygen in the solution was removed by degassing with nitrogen. The amount of cyclohexanone added was appropriately adjusted so that the content of cyclohexanone in the obtained fluorinated polymer composition 4 became the value shown in Table 1. Furthermore, 536 g of CTFE was introduced into the above reactor and the temperature was raised. When the temperature in the reactor reached 65°C, the pressure was 0.59 MPaG. Afterwards, 2 mL of PBPV 5% xylene solution was added to the reactor to start the reaction. As the pressure decreased, the pressure was maintained, and additional monomers CTFE 110 g, CHVE 93 g, and HBVE 24 g were continuously added to the reactor, and PBPV 5% xylene solution was intermittently added to the reactor as a free radical polymerization initiator to carry out polymerization. After the start of polymerization, the total amount of PBPV 5% xylene solution added to the reactor was 55 mL. After 16 hours, the reactor was water-cooled to stop the reaction. After the reaction liquid was cooled to room temperature, the unreacted monomers were rinsed and the reactor was opened. The obtained reaction liquid was transferred to a pressure filter equipped with a No. 63 filter paper for viscosity adjustment, and the aluminum magnesium carbonate was separated by filtration at a pressure of 0.05 MPa. Then, at least a part of the solvent in the reaction liquid was distilled off by a reduced pressure distillation device at 85°C and 55 Torr under reduced pressure heating to obtain a solution containing a fluorine-containing polymer. Thereafter, xylene was added to the solution containing the fluorine-containing polymer to adjust the concentration, and a fluorine-containing polymer composition 4 was obtained.

[Example 5] 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 added to a stainless steel pressure-resistant reactor with a content volume of 2500 mL and equipped with a stirrer, and the dissolved oxygen in the solution was removed by pressurizing, flushing, and degassing with nitrogen. The amount of cyclohexanone added was appropriately adjusted in such a way that the content of cyclohexanone in the obtained fluoropolymer composition 5 became the value shown in Table 1. Then, 622 g of CTFE was introduced, and the temperature was slowly raised, and the reaction was continued while maintaining the temperature at 65°C. After 12 hours, the reactor was water-cooled to stop the reaction. After the reaction liquid is cooled to room temperature, the unreacted monomers are rinsed and the reactor is opened. The obtained reaction liquid is transferred to a pressure filter equipped with a No. 63 filter paper for viscosity adjustment, and potassium carbonate is separated by filtration at a pressure of 0.05 MPa, and then 0.1 g of hydroquinone monomethyl ether (hereinafter referred to as HQMME) is added. Next, at least a portion of the solvent in the reaction liquid is distilled off by a reduced pressure distillation device at 85°C and 55 Torr under reduced pressure heating. Next, diatomaceous earth (median particle size 30.1 μm) with a relative filtering area of 0.06 g/cm ² was added to the reaction solution, mixed and stirred, and then transferred to a pressure filter equipped with a No. 63 filter paper for viscosity adjustment, and a second filtration was performed at a pressure of 0.02 MPa to separate the diatomaceous earth and obtain a solution containing a fluorine-containing polymer. Subsequently, xylene was added to the solution containing the fluorine-containing polymer to adjust the concentration, and a fluorine-containing polymer composition 5 was obtained.

[Example 6] 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 added to a stainless steel pressure-resistant reactor with a content volume of 2500 mL and equipped with a stirrer, and the dissolved oxygen in the solution was removed by pressurizing, flushing, and degassing with nitrogen. The amount of cyclohexanone added was appropriately adjusted in such a way that the content of cyclohexanone in the obtained fluoropolymer composition 6 became the value recorded in Table 1. Then, 660 g of CTFE was introduced, and the temperature was slowly raised, and the reaction was continued while maintaining the temperature at 65°C. After 12 hours, the reactor was water-cooled to stop the reaction. After the reaction liquid is cooled to room temperature, the unreacted monomers are rinsed and the reactor is opened. The obtained reaction liquid is transferred to a pressure filter equipped with a No. 63 filter paper for viscosity adjustment, and potassium carbonate is separated by filtration at a pressure of 0.05 MPa, and then 0.1 g of hydroquinone monomethyl ether (hereinafter referred to as HQMME) is added. Next, at least a portion of the solvent in the reaction liquid is distilled off by a reduced pressure distillation device at 65°C and 45 Torr under reduced pressure heating. Next, diatomaceous earth (median particle size 30.1 μm) with a relative filtering area of 0.06 g/cm ² was added to the reaction solution, mixed and stirred, and then transferred to a pressure filter equipped with a No. 63 filter paper for viscosity adjustment, and a second filtration was performed at a pressure of 0.02 MPa to separate the diatomaceous earth and obtain a solution containing a fluorine-containing polymer. Subsequently, xylene was added to the solution containing the fluorine-containing polymer to adjust the concentration, and a fluorine-containing polymer composition 6 was obtained.

[Example 7] 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 added to a stainless steel pressure-resistant reactor with a content volume of 2500 mL and equipped with a stirrer, and the dissolved oxygen in the solution was removed by pressurizing, flushing, and degassing with nitrogen. The amount of cyclohexanone added was appropriately adjusted in such a way that the content of cyclohexanone in the obtained fluoropolymer composition 7 became the value shown in Table 1. Then, 660 g of CTFE was introduced, and the temperature was slowly raised, and the reaction was continued while maintaining the temperature at 65°C. After 12 hours, the reactor was water-cooled to stop the reaction. After the reaction liquid is cooled to room temperature, the unreacted monomers are rinsed and the reactor is opened. The obtained reaction liquid is transferred to a pressure filter equipped with a No. 63 filter paper for viscosity adjustment, and potassium carbonate is separated by filtration at a pressure of 0.05 MPa, and then 0.1 g of hydroquinone monomethyl ether (hereinafter referred to as HQMME) is added. Next, at least a portion of the solvent in the reaction liquid is distilled off by a reduced pressure distillation device at 65°C and 15 Torr under reduced pressure heating. Next, diatomaceous earth (median particle size 30.1 μm) with a relative filtering area of 0.06 g/cm ² was added to the reaction solution, mixed and stirred, and then transferred to a pressure filter equipped with a No. 63 filter paper for viscosity adjustment, and a second filtration was performed at a pressure of 0.02 MPa to separate the diatomaceous earth and obtain a solution containing a fluorine-containing polymer. Subsequently, xylene was added to the solution containing the fluorine-containing polymer to adjust the concentration, and a fluorine-containing polymer composition 7 was obtained.

[Example 8] Using the fluorine-containing polymer composition 2 of Example 2, the volatile matter was removed by heating under reduced pressure at 65°C in a vacuum dryer for 3 hours. Then, the volatile matter was removed by heating under reduced pressure at 130°C for 20 minutes to obtain a solid fluorine-containing polymer composition 8.

[Coloring after storage] For each fluorine-containing polymer composition, the difference in coloring before and after storage in a constant temperature bath at 70°C for 2 weeks was evaluated based on the following criteria. A: There is no visual difference in coloring before and after storage B: There is a visual difference in coloring before and after storage

[Water content] For the fluoropolymer compositions of each example just after production, the water content in the fluoropolymer compositions was measured by Karl Fischer 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. In addition, the fluoropolymer compositions of Examples 1 to 7 were subjected to direct titration, and the fluoropolymer composition of Example 8 was subjected to water vaporization method, and Karl Fischer titration was performed. A: Water content is less than 1000 mass ppm B: Water content exceeds 1000 mass ppm

[Leveling property] 10 parts by mass of the fluoropolymer in each fluoropolymer composition, 40 parts by mass of titanium oxide (manufactured by DUPONT, Ti-Pure (registered trademark) R960), and xylene in an amount such that the total amount of the fluoropolymer and titanium oxide is 50% by mass of the total amount were mixed, and stirred for 1 hour by a rocking mill to prepare a grinding slurry. Next, 37 parts by mass of the obtained grinding slurry, 30 parts by mass of the fluorinated polymer in each example of the fluorinated polymer composition, 2 parts by mass of DBTDL (Dibutyltin dilaurate) diluted 1/10000, and xylene in an amount such that the total amount of the fluorinated polymer and the amount of titanium oxide is 50% by mass of the total amount were mixed, and stirred again by a swinging grinder for 30 minutes to prepare a main agent. Next, 100 parts by mass of the main agent and an isocyanate curing agent (Desmodur (registered trademark) N3300 manufactured by Bayer) (6.1 parts by mass for Examples 1, 2, 6, 7, and 8, 4.7 parts by mass for Example 3, 5.4 parts by mass for Example 4, and 6.7 parts by mass for Example 5) were mixed to prepare the coating corresponding to each example. <Preparation of a substrate with a coating> The obtained coating was applied to one side of a chromate-treated aluminum plate using an applicator and then kept in an environment of 80°C for 1 hour. After heating, the aluminum plates with coating layers corresponding to each example were placed and cooled to room temperature (23°C) to obtain aluminum plates with coating films (cured films) with a film thickness of 40 μm. ＜Evaluation of leveling properties of coating films＞ 24 hours after the aluminum plates with coating films were manufactured, the leveling properties of the coating films were evaluated according to the following criteria. A: No ripples or patterns were visually observed on the coating surface B: No ripples or patterns were visually observed on the coating surface

[Table 1] example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Composition of fluorinated polymers CTFE unit (mol%) 50 50 50 50 50 50 50 50 EVE unit (mol%) 25 25 - - 40 25 25 25 HBVE unit (mol%) 10 10 9 11 10 10 10 10 CHVE unit (mol%) 15 15 26 39 - 15 15 15 2EHVE unit (mol%) - - 15 - - - - - Composition of fluorinated polymer composition Fluorinated polymer (mass %) 60 60 60 65 50 60 60 98 Cyclohexanone(mass%) 1.17 0.75 1.24 1.54 0.54 3.00 0.40 0.60 Xylene(mass%) 38.83 39.25 38.76 33.46 49.46 37.00 39.60 1.40 Evaluation results Coloring after storage A A A A A B A A Water A A A A A A A B Leveling A A A A A A B A

As shown in Table 1, it was confirmed that the fluorine-containing polymer composition of the present invention suppressed coloring after water inclusion and storage, and when mixed with a coating solvent to produce a coating, the coating film formed using the coating had excellent leveling properties (Examples 1 to 5). Furthermore, the specification, scope of the patent application, and abstract of Japanese Patent Application No. 2022-157420 filed on September 30, 2022 are all cited in this article and introduced as a disclosure of the specification of the present invention.

Claims (6)

A fluorine-containing polymer composition for coating, comprising: a fluorine-containing polymer containing units based on fluoroolefins and units based on monomers without fluorine atoms; cyclohexanone; and a solvent different from the cyclohexanone; and the total amount of the cyclohexanone and the solvent is 10% by mass or more relative to the total mass of the fluorine-containing polymer composition for coating, the content of the cyclohexanone is 0.5 to 2.0% by mass relative to the total mass of the fluorine-containing polymer composition for coating. The fluorine-containing polymer composition for coating as claimed in claim 1, wherein the fluoroolefin is CF ₂ =CFCl. A fluorine-containing polymer composition for coating as claimed in claim 1 or 2, wherein the units based on monomers having no fluorine atoms include at least one of units based on monomers having no fluorine atoms and reactive groups and units based on monomers having reactive groups and having no fluorine atoms. The fluorine-containing polymer composition for coating as claimed in claim 3, wherein the reactive group is a hydroxyl group. The fluorine-containing polymer composition for coating as claimed in claim 1 or 2, wherein the total amount of the cyclohexanone and the solvent is 70 mass % or less relative to the total mass of the fluorine-containing polymer composition for coating. The fluorine-containing polymer composition for coating as claimed in claim 1 or 2, wherein the total amount of the cyclohexanone and the solvent is 30% by mass or more relative to the total mass of the fluorine-containing polymer composition for coating.