Method for producing solid composition

Abstract

Provided is a method for producing a solid composition with which it is possible to efficiently remove a solvent from a fluorine-containing polymer solution. In the method for producing a solid composition according to the present invention, a solvent removal device is used to remove a solvent from a fluorine-containing polymer solution containing a fluorine-containing polymer and the solvent to obtain a solid composition, and the solvent removal device is provided with: a housing unit; a rotating shaft disposed inside the housing part; and a stirring blade connected to the rotating shaft, in which a film-like fluorine-containing polymer solution is formed on the inner wall of the housing part by means of the stirring blade, and the solvent is removed from the film-like fluorine-containing polymer solution, the viscosity of the fluorine-containing polymer solution is 5 cm2 / s or more and less than 35 cm2 / s, and a distance D, which is the shortest distance between the stirring blade and the inner wall of the housing part, is 3 mm or less, or a distance D, which is the shortest distance between the stirring blade and the inner wall of the housing part, is 3 mm or less. The viscosity of the fluorine-containing polymer solution is 35 cm2 / s or more and 150 cm2 / s or less, and the distance (D) is 4-6 mm.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for producing a solid composition. BACKGROUND

[0002] A coating material containing a fluorine-containing polymer is capable of forming a coating film excellent in durability and the like, and thus is attracting attention from an economic and environmental aspect as a material capable of reducing the life cycle cost of a coated article. Among such coating materials containing a fluorine-containing polymer, a powder coating material is widely used as one of coating materials having a small environmental burden.

[0003] Patent Literature 1 discloses "A method for producing a fluorine-containing resin powder having a curable functional group, characterized by adding an anti-gelation agent (B) to a solution or dispersion of a fluorine-containing copolymer (A) having a curable functional group and mixing, and supplying the solution or dispersion to a thin film vacuum evaporation device to remove a solvent from the solution or dispersion."

[0004] Prior Art Documents

[0005] Patent Literature

[0006] Patent Literature 1: International Publication No. 2003 / 051931 SUMMARY

[0007] Problems to be Solved by the Invention

[0008] In recent years, a method capable of more efficiently producing a solid composition, which is a raw material of a powder coating material containing a fluorine-containing polymer, has been sought.

[0009] The present inventors and others have found that, when a fluorine-containing polymer solution containing a fluorine-containing polymer is used to produce a solid composition, there is room for improvement in terms of efficiently removing a solvent, with reference to the method described in Patent Literature 1.

[0010] The present application was made in view of the above problem, and aims to provide a method for producing a solid composition capable of efficiently removing a solvent from a fluorine-containing polymer solution.

[0011] Means for Solving the Problem

[0012] The present inventors and others have conducted intensive research on the above problem, and as a result, have found that, when a solid composition is obtained by removing a solvent from a fluorine-containing polymer solution containing a fluorine-containing polymer and a solvent using a solvent removal device, if a solvent removal device in which the shortest distance between a stirring blade and the inner wall of a housing portion is within an appropriate range is used in accordance with the viscosity of the fluorine-containing polymer solution at 25°C, a desired effect can be obtained, thereby completing the present application.

[0013] That is, the present inventors have found that the above problems can be solved by the following configuration.

[0014] [1] A method for producing a solid composition, characterized by removing a solvent from a fluoropolymer solution containing a fluoropolymer and a solvent using a solvent removal device to obtain a solid composition,

[0015] The solvent removal device is a device that:

[0016] has a cylindrical housing portion into which the fluoropolymer solution is supplied;

[0017] a rotating shaft disposed inside the housing portion and extending in the extension direction of the housing portion; and

[0018] a stirring blade connected to the rotating shaft,

[0019] forms a film of the fluoropolymer solution on the inner wall of the housing portion using the stirring blade that rotates along with the rotation of the rotating shaft, and removes the solvent from the film of the fluoropolymer solution,

[0020] wherein the viscosity of the fluoropolymer solution at 25°C is 5 cm 2 / s or more and less than 35 cm 2 / s, and the shortest distance between the stirring blade and the inner wall of the housing portion, i.e., the distance D, is 3 mm or less; or

[0021] the viscosity of the fluoropolymer solution at 25°C is 35 cm 2 / s or more and 150 cm 2 / s or less, and the distance D is 4 to 6 mm.

[0022] [2] The method for producing a solid composition according to [1], wherein the solvent contains at least one of mixed xylene containing at least 2 or more of o-xylene, m-xylene, and p-xylene, and ethylbenzene.

[0023] [3] The method for producing a solid composition according to [2], wherein the mixed xylene contains all of o-xylene, m-xylene, and p-xylene.

[0024] [4] The method for producing a solid composition according to [2] or [3], wherein the mass ratio of the content of the ethylbenzene to the content of the mixed xylene is 0.1 to 7.0.

[0025] [5] The method for producing a solid composition according to any one of [1] to [4], wherein the solid content concentration of the fluoropolymer solution is 40 to 90 mass%.

[0026] [6] The method for producing a solid composition according to any one of [1] to [5], wherein the fluorine-containing polymer has a unit based on a fluoroolefin.

[0027] [7] The method for producing a solid composition according to any one of [1] to [6], wherein the fluorine-containing polymer has a unit based on chlorotrifluoroethylene and a unit based on a vinyl ether.

[0028] [8] The method for producing a solid composition according to any one of [1] to [7], wherein the viscosity of the fluorine-containing polymer solution at 25°C is 5 cm 2 / s or more and less than 35 cm 2 / s, and the distance D is 1 to 3 mm.

[0029] [9] The method for producing a solid composition according to any one of [1] to [8], wherein the viscosity of the fluorine-containing polymer solution at 25°C is 35 cm 2 / s or more and 150 cm 2 / s or less, and the distance D is 5 to 6 mm.

[0030]

[10] The method for producing a solid composition according to any one of [1] to [9], wherein the solvent removing device has a heating means for heating the housing portion with a heat medium,

[0031] the temperature of the heat medium is 90 to 140°C.

[0032]

[11] The method for producing a solid composition according to any one of [1] to

[10] , wherein the solid composition is used as a raw material for a powder paint.

[0033] Effects of the Invention

[0034] According to the present application, it is possible to provide a method for producing a solid composition capable of efficiently removing a solvent from a fluorine-containing polymer solution. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 is a schematic side view that schematically shows an example of a solvent removing device used in the method for producing a solid composition of the present application.

[0036] Figure 2 is a schematic cross-sectional view that schematically shows the A-A cross section of the solvent removing device of Figure 1 DETAILED DESCRIPTION

[0037] The meanings of the terms in the present application are shown below.

[0038] ​The numerical range represented by "~" means a range including the numerical values recited before and after "~" as lower limit value and upper limit value. In the numerical range recited in the present specification, the upper limit value or lower limit value recited in a certain numerical range can be replaced with the upper limit value or lower limit value of other recited numerical range. In addition, in the numerical range recited in the present specification, the upper limit value or lower limit value recited in a certain numerical range can be replaced with the value shown in the examples.

[0039] In the present specification, each component can be used singly with a substance conforming to the component, or two or more kinds can be used in combination. Here, when two or more kinds of substances are used in combination with respect to each component, the relevant content of the component means the total content of the combined substances unless otherwise specified.

[0040] In the present specification, a combination of two or more preferred modes is a more preferred mode.

[0041] The unit means a collective term of a group of atoms based on one molecule of the above-mentioned monomer directly formed by polymerization of the monomer and a group of atoms obtained by chemical conversion of a part of the above-mentioned group of atoms. The content (mol%) of each unit with respect to the total units contained in the polymer can be determined by analyzing the polymer by nuclear magnetic resonance spectroscopy, or can be determined from the amount of ingredients used in the production of the polymer.

[0042] The (meth)acryloyl group means a collective term of acryloyl group and methacryloyl group.

[0043] The hydrolyzable silyl group means a group that can form a silanol group by hydrolysis reaction.

[0044] The acid value and the hydroxyl value are values measured according to the method of JIS K 0070-3 (1992), respectively.

[0045] The glass transition temperature (Tg) is the midpoint glass transition temperature of the polymer measured by differential scanning calorimetry (DSC) method.

[0046] The viscosity of the fluorine-containing polymer solution at 25°C is a value measured by the Gardner-type bubble viscometer method of JIS K5600-2-2.

[0047] The melt viscosity is a value of the melt viscosity of the sample at 170°C when the temperature is raised from 130°C to 200°C at a temperature raising rate of 10°C / minute and measured using a rotational rheometer.

[0048] The number average molecular weight (Mn) and the weight average molecular weight (Mw) are values measured using polystyrene as a standard substance and by size exclusion chromatography (gel permeation chromatography). In addition, the ratio of Mw to Mn indicates the molecular weight distribution, and is also referred to as Mw / Mn.

[0049] The average particle size of particles refers to a value of 50% diameter obtained by calculating the volume average from particle size distribution measured using a known particle size distribution measuring apparatus (Sympatec, trade name: Helos-Rodos, etc.) based on the laser diffraction method.

[0050] The film thickness is a value measured using an eddy current film thickness meter (manufactured by SANKO ELECTRONIC, trade name: EDY-5000, etc.).

[0051] The method for producing a solid composition of the present invention (hereinafter also referred to as the present production method) is a method for producing a solid composition comprising removing the solvent from a fluoropolymer solution containing a fluoropolymer and a solvent using a solvent removal apparatus to obtain a solid composition.

[0052] The above-mentioned solvent removal device is a device as follows: it comprises: a cylindrical shell portion, the interior of which is supplied with the above-mentioned fluoropolymer solution; a rotating shaft, which is arranged inside the above-mentioned shell portion and extends along the extension direction of the above-mentioned shell portion; and a stirring blade, which is connected to the above-mentioned rotating shaft. The above-mentioned stirring blade rotates as the above-mentioned rotating shaft rotates, forming a film of the above-mentioned fluoropolymer solution on the inner wall of the above-mentioned shell portion, and removing the solvent from the film-shaped above-mentioned fluoropolymer solution.

[0053] The viscosity of the fluorinated polymer solution at 25°C is 5 cm 2 / s or more and less than 35cm 2 / s, and the shortest distance D between the stirring blade and the inner wall of the housing is 3 mm or less, or the viscosity of the fluoropolymer solution at 25°C is 35 cm 2 / s or more and 150cm 2 / s or less, and the distance D is 4 to 6 mm.

[0054] As will be described later, in the method for producing a solid composition using a solvent removal device, the fluoropolymer solution as a raw material flows gradually downward along the inner wall of the shell portion, and a certain distance (equivalent to the following) is used to separate the fluoropolymer solution from the inner wall. Figure 2 The stirring blades are configured to form a thin film at a distance D).

[0055] The present inventors have found that the viscosity of the fluoropolymer solution and the distance D (see below) Figure 2 ) is closely related to the removal efficiency of the solvent contained in the fluoropolymer solution.

[0056] Specific findings: The viscosity at 25°C is 5cm 2 / s or more and less than 35cm 2When the distance D is 3 mm or less, even if the amount of the fluorine-containing polymer solution supplied is large, the solvent can be efficiently removed. That is, it is presumed that, because the fluorine-containing polymer solution is of low viscosity, the solution easily flows down along the inner wall to the lower portion, and as a result, even if a large amount of the fluorine-containing polymer solution is supplied, the distance D is sufficiently small, so the fluorine-containing polymer solution is prevented from falling down in a short time, the heat conduction efficiency is increased, and thus the solvent removal efficiency is improved.

[0057] Further, it was found that, when the viscosity at 25°C is 35 cm 2 and less than 150 cm 2 When the distance D is 4 to 6 mm, even if the amount of the fluorine-containing polymer solution supplied is large, the solvent can be efficiently removed. That is, if the distance D is 4 mm or more, the liquid volume of the fluorine-containing polymer solution in a state where heat conduction is not easy remains small in the vicinity of the stirring blade, so it is presumed that, even if a large amount of the fluorine-containing polymer solution is supplied, the solvent is not sufficiently removed. Further, it is presumed that, if the distance D is 6 mm or less, the fluorine-containing polymer solution is sufficiently thinned, so the heat conduction efficiency for the fluorine-containing polymer solution becomes good, and the solvent is sufficiently removed.

[0058] Here, efficient removal means that, when 0.25 g of the solid composition, which has been discharged from the solvent removal device and immediately cooled to room temperature, is heated at 110°C for 3 hours, and the mass of the residue of the solid composition is found, the mass of the solid component of the solid composition (mass %) calculated using the following equation is 99.0 mass % or more.

[0059] Mass of solid component of solid composition (mass %) = 100 x (mass of residue of solid composition) / (mass of solid composition discharged from solvent removal device and immediately cooled to room temperature)

[0060] From the viewpoint of blocking resistance, the mass of the solid component of the solid composition is preferably 99.0 mass % or more, and more preferably 99.5 mass % or more.

[0061] The fluorine-containing polymer solution used in the production method contains a fluorine-containing polymer and a solvent.

[0062] The fluorine-containing polymer preferably has a fluoroolefin-based unit.

[0063] The fluoroolefin is an olefin in which one or more hydrogen atoms are substituted with a fluorine atom. One or more hydrogen atoms in the fluoroolefin that are not substituted with a fluorine atom are optionally substituted with a chlorine atom. The number of carbon atoms in the fluoroolefin is preferably 2 to 6, and more preferably 2 to 4.

[0064] As the fluoroolefin, CF2=CF2, CF2=CFCl (trifluorochloroethylene), CF2=CHF, CH2=CF2, CF2=CFCF3, CF3-CH=CHF, CF3-CF=CH2, etc. can be exemplified. From the viewpoint of weather resistance and polymerizability with monomers other than fluoroolefins, the fluoroolefin is preferably CF2=CF2 or CF2=CFCl, more preferably CF2=CFCl.

[0065] Two or more kinds of fluoroolefins can be used in combination.

[0066] From the viewpoint of more excellent weather resistance of the coating film obtained using the fluorine-containing polymer, the content of the unit based on the fluoroolefin is preferably 30 to 70 mol%, more preferably 40 to 60 mol%, further preferably 45 to 55 mol% relative to the total repeating units of the fluorine-containing polymer.

[0067] The fluorine-containing polymer preferably has at least one unit selected from the group consisting of a unit based on a vinyl ether and a unit based on a vinyl ester, more preferably a unit based on a vinyl ether. Further, from the viewpoint of more excellent weather resistance of the coating film obtained using the fluorine-containing polymer, more preferably has a unit based on a fluoroolefin and at least one unit selected from the group consisting of a unit based on a vinyl ether and a unit based on a vinyl ester, further preferably has a unit based on trifluorochloroethylene and at least one unit selected from the group consisting of a unit based on a vinyl ether and a unit based on a vinyl ester, particularly preferably has a unit based on trifluorochloroethylene and a unit based on a vinyl ether.

[0068] The vinyl ether can be a vinyl ether having a crosslinkable group, or a vinyl ether not having a crosslinkable group.

[0069] From the viewpoint of further improving the durability of the coating film obtained using the fluorine-containing polymer, the vinyl ether preferably has a crosslinkable group.

[0070] As a specific example of the crosslinkable group, at least one group selected from the group consisting of a hydroxyl group, an amino group, an epoxy group, an oxetanyl group, a hydrolyzable silyl group, a sulfo group, and a carboxyl group can be exemplified, from the viewpoint of further improving the hardness of the coating film obtained using the fluorine-containing polymer, a hydroxyl group or a carboxyl group is preferred, and a hydroxyl group is more preferred. Note that the sulfo group and the carboxyl group can be ionized to become -SO3 - or -COO - , or form a salt with a cation to become -SO3 - Na + or -COO - Na + , etc.

[0071] The number of crosslinkable groups can be 1 or more than 2. Two or more crosslinkable groups can be used in combination.

[0072] Two or more vinyl ethers can be used in combination, and it is preferable to use a combination of a vinyl ether having a crosslinkable group and a vinyl ether not having a crosslinkable group.

[0073] The vinyl ether can or can not have a fluorine atom, and it is preferable that the vinyl ether not have a fluorine atom.

[0074] Two or more vinyl ethers having a crosslinkable group can be used in combination.

[0075] As specific examples of the vinyl ether having a hydroxyl group, CH2=CHO-CH2-cycloC6H 10 -CH2OH, CH2=CHOCH2CH2OH, CH2=CHOCH2CH2CH2CH2OH.

[0076] Note that "-cycloC6H 10 -" indicates a cyclohexylene group, and the bonding site of "-cycloC6H 10 -" is usually 1,4.

[0077] Two or more vinyl ethers having a hydroxyl group can be used in combination.

[0078] As specific examples of the vinyl ether having a carboxyl group, CH2=CHO(CH2) n12 OC(O)CH2CH2COOH (wherein n12 represents an integer of 1 to 10) can be given.

[0079] Two or more vinyl ethers having a carboxyl group can be used in combination.

[0080] As specific examples of the vinyl ether not having a crosslinkable group, ethyl vinyl ether, t-butyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexyl vinyl ether, and cyclohexylmethyl vinyl ether can be given.

[0081] Two or more vinyl ethers not having a crosslinkable group can be used in combination.

[0082] The content of the vinyl ether-based unit is preferably 1 to 80 mol%, more preferably 10 to 70 mol%, and further preferably 20 to 60 mol% relative to the total repeating units of the fluorine-containing polymer.

[0083] When the units based on vinyl ethers include units based on vinyl ethers having a cross-linkable group, the content of the units based on vinyl ethers having a cross-linkable group is preferably 1 to 30 mol%, more preferably 3 to 25 mol%, and further preferably 5 to 20 mol% relative to the total repeating units of the fluorine-containing polymer, from the viewpoint of being able to further improve the hardness of the coating film obtained using the fluorine-containing polymer.

[0084] When the units based on vinyl ethers include units based on vinyl ethers not having a cross-linkable group, the content of the units based on vinyl ethers not having a cross-linkable group is preferably 1 to 70 mol%, more preferably 5 to 60 mol%, and further preferably 10 to 50 mol% relative to the total repeating units of the fluorine-containing polymer, from the viewpoint of being able to further improve the smoothness and hardness of the coating film obtained using the fluorine-containing polymer.

[0085] The fluorine-containing polymer can include units other than at least one unit selected from the group consisting of units based on vinyl ethers and units based on vinyl esters (hereinafter also referred to as other units) and units based on fluoroolefins, and is preferably substantially free of other units from the viewpoint of the weather resistance of the coating film obtained using the fluorine-containing polymer being more excellent.

[0086] Here, substantially free of other units means that the content of other units is 0.1 mol% or less relative to the total repeating units of the fluorine-containing polymer.

[0087] As a specific example of other units, units based on allyl ethers can be given.

[0088] From the viewpoint of being able to further improve the hardness of the coating film obtained using the fluorine-containing polymer, the fluorine-containing polymer preferably does not have a carboxyl group. In this case, the fluorine-containing polymer preferably has a hydroxyl group.

[0089] The fluorine-containing polymer preferably includes units based on chlorotrifluoroethylene, units based on vinyl ethers having a cross-linkable group, and units based on vinyl ethers not having a cross-linkable group, and is more preferably a copolymer (fluorine-containing copolymer) composed of units based on chlorotrifluoroethylene, units based on vinyl ethers having a cross-linkable group, and units based on vinyl ethers not having a cross-linkable group.

[0090] In the fluorine-containing polymer, the content of units based on chlorotrifluoroethylene, units based on vinyl ethers having a cross-linkable group, and units based on vinyl ethers not having a cross-linkable group is preferably 30 to 70 mol%, 1 to 30 mol%, and 1 to 70 mol%, and the content is more preferably 45 to 55 mol%, 5 to 20 mol%, and 10 to 50 mol%, respectively, relative to the total units included in the fluorine-containing polymer. If the content of each unit is in the above range, the durability, smoothness, and weather resistance of the coating film can be balanced.

[0091] From the viewpoint of further improving the blocking resistance of the powder coating containing the fluorine-containing polymer and the surface smoothness of the coating film obtained by using the above powder coating, the Tg of the fluorine-containing polymer is preferably from 20 to 60°C, more preferably from 25 to 60°C, and further preferably from 30 to 55°C.

[0092] The melt viscosity of the fluorine-containing polymer at 170°C is preferably from 0.1 to 450 Pa-s, more preferably from 1 to 450 Pa-s, and further preferably from 3 to 400 Pa-s.

[0093] In the case where the fluorine-containing polymer has a hydroxyl value, the hydroxyl value of the fluorine-containing polymer is preferably more than 0 mgKOH / g and less than 150 mgKOH / g, more preferably from 5 to 120 mgKOH / g, further preferably from 15 to 110 mgKOH / g, and particularly preferably from 30 to 100 mgKOH / g.

[0094] In the case where the fluorine-containing polymer has an acid value, the acid value of the fluorine-containing polymer is preferably more than 0 mgKOH / g and less than 10 mgKOH / g, more preferably from 2 to 8 mgKOH / g, and further preferably from 3 to 7 mgKOH / g.

[0095] From the viewpoint of more excellent effects of the present application, the Mw of the fluorine-containing polymer is preferably from 10,000 to 60,000, more preferably from 12,000 to 55,000, and further preferably from 15,000 to 50,000.

[0096] From the viewpoint of more excellent effects of the present application, the Mn of the fluorine-containing polymer is preferably from 5,000 to 20,000, more preferably from 6,000 to 18,000, and further preferably from 7,000 to 16,000.

[0097] From the viewpoint of more excellent effects of the present application, the Mw / Mn (molecular weight distribution) of the fluorine-containing polymer is preferably from 2.0 to 3.5, more preferably from 2.1 to 3.3, and further preferably from 2.2 to 3.2.

[0098] If the Mw and the Mn are in the above ranges, the viscosity of the fluorine-containing polymer solution easily becomes an appropriate range targeted, and the solvent can be efficiently removed.

[0099] The content of the fluorine-containing polymer with respect to the total mass of the fluorine-containing polymer solution is preferably from 40 to 90 mass%, more preferably from 50 to 80 mass%, and further preferably from 60 to 70 mass%. If the content of the fluorine-containing polymer is 40 mass% or more, the productivity of the solid composition in the operation per unit time of the solvent removal apparatus is excellent. In addition, if the content of the fluorine-containing polymer is 90 mass% or less, the viscosity adjustment of the fluorine-containing polymer solution is excellent.

[0100] As a method for producing the fluorine-containing polymer, solution polymerization, emulsion polymerization, suspension polymerization, and the like can be exemplified.

[0101] As the fluorine-containing polymer, commercially available products can be used, and as specific examples, the "LUMIFLON" series (manufactured by AGC), the "ZEFFLE" series (manufactured by Daikin Industries, Ltd.), the "Eterflon" series (manufactured by ETERNAL), the "Zendura" series (manufactured by Honeywell), and the "ZHM" series (Changshu 3F) can be exemplified.

[0102] Two or more kinds of the fluorine-containing polymers can be used in combination.

[0103] The solvent contained in the fluorine-containing polymer solution can be a polymerization solvent used in the production of the fluorine-containing polymer, or a solvent added later (for example, added when the fluorine-containing polymer solution is prepared).

[0104] As the solvent, a ketone-based solvent, an ester-based solvent, a hydrocarbon-based solvent, an alcohol-based solvent, a glycol ether-based solvent, a glycol ester-based solvent, and the like can be exemplified.

[0105] As specific examples of the ketone-based solvent, acetone, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, diacetone alcohol, and cyclohexanone can be exemplified.

[0106] As specific examples of the ester-based solvent, ethyl acetate and butyl acetate can be exemplified.

[0107] As specific examples of the hydrocarbon-based solvent, hexane, heptane, cyclohexane, o-xylene, m-xylene, p-xylene, and ethylbenzene can be exemplified.

[0108] As specific examples of the alcohol-based solvent, butanol can be exemplified.

[0109] As specific examples of the glycol ether-based solvent, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, and propylene glycol monopropyl ether can be exemplified.

[0110] As specific examples of the glycol ester-based solvent, 1-methoxypropyl-2-acetate can be exemplified.

[0111] Two or more kinds of the solvents can be used in combination.

[0112] From the viewpoint of more excellent efficiency of removal from the solvent, the solvent preferably contains at least one of ethylbenzene and mixed xylene, and more preferably contains both of ethylbenzene and mixed xylene.

[0113] The mixed xylene refers to a mixture of structural isomers of xylene including ortho-xylene, meta-xylene, and para-xylene. The mixed xylene is a mixed xylene including at least two or more of ortho-xylene, meta-xylene, and para-xylene, and preferably a mixed xylene including all of ortho-xylene, meta-xylene, and para-xylene.

[0114] The solid content concentration of the fluorine-containing polymer solution is preferably 40 to 90% by mass, more preferably 50 to 80% by mass, further preferably 55 to 75% by mass, and particularly preferably 60 to 70% by mass, from the viewpoint of more excellent efficiency of removal of the solvent.

[0115] Here, the solid content concentration of the fluorine-containing polymer solution is calculated by obtaining the mass of the residue of the fluorine-containing polymer solution after heating 1 g of the fluorine-containing polymer solution at 110°C for 3 hours using a hot air drier, and calculating using the following equation.

[0116] The solid content concentration of the fluorine-containing polymer solution (% by mass) = 100 x (the mass of the residue of the fluorine-containing polymer solution) / (the mass of the fluorine-containing polymer solution before heating)

[0117] When the fluorine-containing polymer solution contains both ethylbenzene and mixed xylene, the mass ratio of the content of ethylbenzene to the content of mixed xylene (the content of ethylbenzene / the content of mixed xylene) is preferably 0.1 to 7.0, more preferably 0.2 to 4.0, and further preferably 0.2 to 1.5, from the viewpoint of more excellent efficiency of removal of the solvent.

[0118] The fluorine-containing polymer solution can contain components other than the fluorine-containing polymer and the solvent (hereinafter also referred to as other components).

[0119] As specific examples of the other components, a compound containing a piperidyl group and a polymerization inhibitor can be given.

[0120] When the fluorine-containing polymer solution contains the other components, the content of the other components is preferably more than 0% by mass and 2% by mass or less, and more preferably 0.005 to 1.5% by mass, with respect to the total mass of the fluorine-containing polymer solution.

[0121] The compound containing a piperidyl group refers to a compound containing a piperidyl group or a piperidyl group having a substituent, and more preferably a compound containing a piperidyl group having a substituent.

[0122] The piperidyl group having a substituent is preferably a tetrasubstituted piperidyl group, and more preferably a 2,2,6,6-tetrasubstituted piperidyl group.

[0123] The compound containing a piperidyl group is preferably a compound containing two or more piperidyl groups or a piperidyl group having a substituent.

[0124] The compound containing a piperidyl group can be used in combination with two or more kinds.

[0125] When the fluorine-containing polymer solution contains the compound containing a piperidyl group, the content of the compound containing a piperidyl group is preferably more than 0 mass% and 2 mass% or less, more preferably 0.1 to 1.5 mass%, with respect to the total mass of the fluorine-containing polymer solution.

[0126] The viscosity of the fluorine-containing polymer solution at 25°C is 5 to 150 cm 2 / s.

[0127] The viscosity of the fluorine-containing polymer solution can be adjusted to the above range depending on, for example, the content of the fluorine-containing polymer and the solvent contained in the fluorine-containing polymer solution, the kinds of the fluorine-containing polymer and the solvent, and the like.

[0128] Figure 1 is a schematic side view showing an example of a solvent removal device used in the present production method, showing a part of the internal structure thereof.

[0129] The solvent removal device 1 has: a cylindrical housing portion 10 inside of which the fluorine-containing polymer solution is supplied; a liquid distribution disk 11; a raw material inlet 20 provided at the upper portion of the housing portion 10 and used for introducing the fluorine-containing polymer solution into the inside of the housing portion 10; a concentrate outlet 21 provided at the lower portion of the housing portion 10 and becoming an outlet for taking out the present solid composition from the solvent removal device 1; and a vapor outlet 22 used for discharging the solvent removed from the fluorine-containing polymer solution.

[0130] An upper rotary shaft 12a extending along the extension direction of the housing portion 10 and a stirring blade 12b connected to the upper rotary shaft 12a and extending along a direction intersecting the upper rotary shaft 12a are arranged inside the housing portion 10.

[0131] The stirring blade 12b is provided with a plurality of portions along the length direction of the upper rotary shaft 12a, and has an inclination along a direction intersecting the upper rotary shaft 12a. The stirring blade 12b does not necessarily need to have the inclination.

[0132] The raw material inlet 20 is connected to a raw material supply pump not shown, whereby a prescribed amount of the fluorine-containing polymer solution can be supplied to the inside of the housing portion 10.

[0133] The vapor outlet 22 can be connected to a vacuum pump not shown. Thereby, the solvent can be removed under reduced pressure, and thus the production efficiency of the solid composition is further improved.

[0134] The solvent removal device 1 has a scraping blade 13 provided below the stirring blade 12b for scraping the solid composition downward, and a lower rotary shaft 14a provided below the scraping blade 13, which has a screw blade 14b for taking out the solid composition from the concentrate outlet 21.

[0135] The scraping blade 13 is rotated by the driving force of the upper rotary shaft 12a, and thus is linked to the operation of the stirring blade 12b.

[0136] The screw blade 14b is rotated by the driving force of the lower rotary shaft 14a, and is not linked to the operation of the upper rotary shaft 12a.

[0137] The solvent removal device 1 has a heating jacket 30 provided so as to cover the outer periphery of the housing portion 10 for heating the inner wall of the housing portion 10.

[0138] The heating jacket 30 has a heat medium inlet 31 and a heat medium inlet 32, and a heat medium outlet 33 and a heat medium outlet 34, which become heat medium paths.

[0139] If the fluoropolymer solution is supplied from the raw material inlet 20 to the inside of the housing portion 10, the fluoropolymer solution is transported to the upper portion of the inner wall 10a of the housing portion 10 by the liquid distribution plate 11.

[0140] The fluoropolymer solution transported to the upper portion of the inner wall 10a is thinned by the stirring blade 12b driven to rotate by the rotation of the upper rotary shaft 12a, and the solvent is removed during the movement downward. The removed solvent is discharged from the vapor outlet 22.

[0141] The solid composition obtained by removing the solvent from the fluoropolymer solution is scraped to the position of the screw blade 14b by the scraping blade 13, and is taken out to the outside of the machine from the concentrate outlet 21 by the screw blade 14b. The solid composition taken out to the outside of the machine can be cooled to be solidified.

[0142] Here, in the production of the solid composition, the housing portion 10 is preferably heated by the heat medium supplied to the heating jacket 30.

[0143] Further, in the production of the solid composition, in order to efficiently distill and remove the solvent and to suppress the coloring and decomposition of the solid composition, the inside of the housing portion 10 is preferably kept at a negative pressure by a not-shown vacuum pump.

[0144] Figure 2 is a schematic cross-sectional view of the solvent removal device 1 cut along the direction intersecting the longitudinal direction of the rotary shaft 12a (A-A line of Figure 1 ).

[0145] In the present invention, a solvent removal device is used in which the shortest distance D between the stirring blade 12 b and the inner wall surface 10 a of the housing 10 is designed according to the viscosity of the fluoropolymer solution supplied to the raw material inlet 20 .

[0146] Specifically, in this production method, the viscosity of the fluorinated polymer solution at 25°C is 5 cm 2 / s or more and less than 35cm 2 When the viscosity is within the viscosity range X (hereinafter referred to as viscosity range X), a solvent removal device is used in which the distance D is set to 3 mm or less. In the case of viscosity range X, from the perspective of thermal conductivity efficiency, the distance D is 3 mm or less, preferably 2 mm or less. From the perspective of equipment protection and setting accuracy, it is preferably 0.5 mm or more, more preferably 1 mm or more.

[0147] On the other hand, in the present production method, the viscosity of the fluorinated polymer solution at 25°C is 35 cm 2 / s or more and 150cm 2 When the viscosity is less than 1 / s (hereinafter referred to as viscosity range Y), a solvent removal device is used in which the distance D is set to 4 to 6 mm. In the case of viscosity range Y, from the perspective of thermal conductivity efficiency, the distance D is 6 mm or less, preferably 5.5 mm or less, and from the perspective of reducing the effect of liquid accumulation near the stirring blade 12b, it is 4 mm or more, preferably 5 mm or more.

[0148] When the viscosity of the fluoropolymer solution at 25°C is within the range X, the film thickness of the fluoropolymer solution formed by the stirring blade 12b is preferably 0.5 to 3 mm, more preferably 1 to 2 mm. On the other hand, when the viscosity of the fluoropolymer solution at 25°C is within the range Y, the film thickness is preferably 4 to 6 mm, more preferably 5 to 6 mm.

[0149] From the viewpoint of easily achieving the target solid content mass, the internal pressure of the housing 10 is preferably 10 Torr or less, more preferably 5 Torr or less, and even more preferably 3 Torr or less.

[0150] The lower limit of the internal pressure of the housing 10 is usually 1 Torr or more.

[0151] From the viewpoint of better solvent removal efficiency and easier suppression of coloration and decomposition of the solid composition, the temperature of the heating medium is preferably 90 to 140°C, more preferably 95 to 135°C, further preferably 100 to 130°C, and particularly preferably 105 to 120°C.

[0152] From the viewpoint of more excellent effects of the present application, the supply amount (L / H) of the fluoropolymer solution supplied from the raw material inlet 20 to the inside of the housing portion 10 is preferably 20 to 60, more preferably 20 to 50, further preferably 25 to 47, and particularly preferably 25 to 45.

[0153] In the present specification, in the case of "the supply amount of the fluoropolymer solution is large", "a large amount of the fluoropolymer solution", it means that the supply amount of the fluoropolymer solution is 20 (L / H) or more. According to the present production method, even in the case where the supply amount of the fluoropolymer solution is as large as 20 (L / H) or more, the solvent can be efficiently removed.

[0154] Note that the unit L / H means liter / hour.

[0155] From the viewpoint of more excellent solvent removal efficiency, the rotation speed of the stirring blade 12b is preferably 300 to 700 rpm, more preferably 400 to 600 rpm, further preferably 450 to 550 rpm, and particularly preferably 470 to 520 rpm.

[0156] From the viewpoint of more appropriate residence time of the solid composition in the device and more excellent heat conduction efficiency, the rotation speed of the screw blade 14b is preferably 20 to 90 rpm, more preferably 50 to 80 rpm, further preferably 60 to 80 rpm, and particularly preferably 65 to 80.

[0157] From the viewpoint of more excellent effects of the present application, the area of the region (hereinafter also referred to as a guide surface) in the inner wall 10a corresponding to the region from the highest position of the stirring blade 12b disposed at the uppermost portion to the lowest position of the rotating blade 12b disposed at the lowermost portion is preferably 0.1 to 2 m 2 , more preferably 0.1 to 1 m 2 , and further preferably 0.2 to 0.5 m 2 .

[0158] The solid composition (hereinafter also referred to as the present solid composition) obtained by the present production method contains the above-described fluoropolymer.

[0159] The solid composition means a composition in which the solid content mass is 99.0 mass% or more. The solid content mass of the solid composition means the proportion of the mass of the residue remaining after 0.25 g of the solid composition is heated at 110°C for 3 hours to the 0.25 g of the solid composition before heating.

[0160] The content of the fluoropolymer is preferably 98.0 to 99.9 mass%, and more preferably 98.3 to 99.8 mass% with respect to the total mass of the present solid composition.

[0161] The present solid composition can contain a solvent. When the present solid composition contains a solvent, the content of the solvent is preferably more than 0 mass% and 1.0 mass% or less, more preferably 0.01 to 0.5 mass%, further preferably 0.05 to 0.3 mass%, with respect to the total mass of the present solid composition.

[0162] The present solid composition can contain a component other than the fluorine-containing polymer and the solvent (hereinafter also referred to as other component).

[0163] As specific examples of the other component, a compound containing a piperidyl group, a polymerization inhibitor can be given.

[0164] When the present solid composition contains the other component, the content of the other component is preferably 0.01 to 2.0 mass%, more preferably 0.1 to 1.7 mass%, with respect to the total mass of the present solid composition.

[0165] The present solid composition is preferably used as a raw material for a powder paint.

[0166] The powder paint of the present application (hereinafter also referred to as the present paint) contains the fluorine-containing polymer contained in the present solid composition.

[0167] The content of the fluorine-containing polymer is preferably 30 to 60 mass%, more preferably 40 to 55 mass%, with respect to the total mass of the present paint.

[0168] The present paint can further contain an additive.

[0169] As specific examples of the additive, pigments, curing agents, catalysts (curing catalysts and the like), polymers other than the above (for example, polyester resins, (meth)acrylic resins, epoxy resins), fillers (resin beads and the like), light stabilizers, ultraviolet absorbers, matting agents, surface modifiers, degassing agents, flow agents, heat stabilizers, antistatic agents, rust preventives, silane coupling agents, low-stain treatment agents, plasticizers, adhesives, and the like can be given.

[0170] The present paint can be produced by mixing the present solid composition and the additive as needed. The present solid composition and the additive mixed can be in a powder form or a pellet form, respectively, independently.

[0171] As one mode of the production method of the present paint, a method of melt-kneading the present solid composition and the additive used as needed and then cooling and pulverizing to obtain a powder paint can be given. As the temperature of the melt-kneading, 80 to 130°C is preferable.

[0172] Further, as one mode of the production method of the present paint, a method in which a powder of the present solid composition is mixed with a powder of an additive used as needed to obtain a powder paint can be exemplified. This method is also called dry mixing, which is a method in which melt kneading is not performed at the time of mixing.

[0173] The pulverization can be performed using a pulverizer such as a pin mill, a hammer mill, or a jet mill. It is preferable to classify the pulverized product after the pulverization to integrate the particle diameter of the obtained powder paint. The average particle diameter of the powder paint is preferably 1 to 100 μm, and more preferably 10 to 80 μm.

[0174] The coating film of the present application (hereinafter also referred to as the present coating film) is formed by supplying the present paint to a substrate.

[0175] Further, the coated article of the present application has a substrate and a coating film, which is disposed on the substrate and formed from the present paint.

[0176] As a specific example of the material of the substrate, an inorganic substance, an organic substance, and an organic-inorganic composite material can be exemplified.

[0177] As a specific example of the inorganic substance, concrete, natural stone, glass, and metal (iron, stainless steel, aluminum, copper, brass, titanium, and the like) can be exemplified.

[0178] As a specific example of the organic substance, plastic, rubber, adhesive, and wood can be exemplified.

[0179] As a specific example of the organic-inorganic composite material, fiber-reinforced plastic, resin-reinforced concrete, and fiber-reinforced concrete can be exemplified.

[0180] Further, the substrate can be subjected to a publicly known surface treatment (chemical conversion treatment, etc.). Further, a resin layer (polyester resin layer, acrylic resin layer, silicone resin layer, etc.) formed by having a coating primer or the like on the surface of the substrate in advance, etc. can be present.

[0181] As the material of the substrate, metal is preferable, and iron, an alloy containing iron (for example, carbon steel, stainless steel), and aluminum are more preferable.

[0182] As a specific example of the shape of the substrate, a flat plate shape, a spherical shape, and a rod shape can be exemplified.

[0183] The film thickness of the present coating film is preferably 20 to 1,000 μm, and more preferably 20 to 500 μm.

[0184] The coated article of the present application is preferably produced by supplying (coating) the present paint to the surface of a substrate to form a coated layer, and heating the obtained coated layer, followed by cooling.

[0185] As a method for forming the coating layer, electrostatic coating, electrostatic blow-spray, electrostatic immersion, flow immersion, blow-spray, and the like can be exemplified, and electrostatic coating using a powder coating gun is preferable.

[0186] As a specific example of the powder coating gun, a corona charging type coating gun and a friction charging type coating gun can be exemplified. The corona charging type coating gun is a coating gun in which powder paint is blown and sprayed by corona discharge treatment. The friction charging type coating gun is a coating gun in which powder paint is blown and sprayed by friction charging treatment.

[0187] The heating temperature during the heat treatment is preferably 120 to 250°C. The heat maintenance time is usually 2 to 60 minutes. After the heat treatment, cooling to 20 to 25°C is preferable. By the heat treatment and cooling, the coating layer is caused to melt and solidify (melt-solidification), and the present coating film is formed.

[0188] Examples

[0189] Hereinafter, the present application will be described in detail by citing examples. Examples 1-1 to 1-6 and Examples 2-1 to 2-6 are examples, and Examples 1-7, 1-8, 2-7, and 2-8 are comparative examples. Among them, the present application is not limited to these examples. Note that the compounding amount of each component in the tables described later indicates the mass basis unless otherwise specified.

[0190] [Synthesis Example 1]

[0191] Into a stainless steel autoclave reactor having a content volume of 2500 ml equipped with a stirrer, 8.6 g of a piperidyl group-containing compound (manufactured by BASF Corporation, trade name "TINUVIN 292", a mixture of bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and 1,2,2,6,6-pentamethyl-4-piperidyl sebacate methyl ester (mass ratio 3:1) ), 17 g of a hydrotalcite (manufactured by Kyowa Chemical Industry Co., Ltd., trade name "KW500", particle size 45 μm or less: 38%, particle size 45 to 75 μm: 35%, particle size 75 to 106 μm: 21%, particle size 106 to 500 μm: 6%), 850 g of a xylene / ethylbenzene mixed solvent (the xylene / ethylbenzene mixed solvent refers to a mixed solvent containing ethylbenzene and mixed xylene containing o-xylene, m-xylene and p-xylene. The same applies hereinafter.), 196 g of ethyl vinyl ether (hereinafter also referred to as EVE), 123 g of 4-hydroxybutyl vinyl ether (hereinafter also referred to as HBVE) and 198 g of cyclohexyl vinyl ether (hereinafter also referred to as CHVE) were charged, and dissolved oxygen in the liquid was removed by nitrogen-based degassing. Further, 629 g of chlorotrifluoroethylene (hereinafter also referred to as CTFE) was introduced into the reactor and warmed. The temperature in the reactor was heated to 65°C. Thereafter, 2 ml of a 20% xylene solution of t-butyl peroxy pivalate (hereinafter also referred to as PBPV) was added to the reactor to start the reaction.

[0192] Thereafter, the polymerization was carried out by intermittently adding a 20% xylene solution of PBPV as a radical polymerization initiator to the reactor. The total amount of the 20% xylene solution of PBPV intermittently added to the reactor after the start of the polymerization was 50 ml. After 16 hours, the reaction was stopped by water-cooling the reactor.

[0193] After the reaction liquid was cooled to room temperature (23°C, the same applies hereinafter), unreacted monomers were purged, and the insoluble components of the obtained reaction liquid were removed by filtration. Further, concentration adjustment was performed so that the solid content concentration became 60%, and a fluorine-containing polymer solution A-1 containing fluorine-containing polymer 1 was obtained. The viscosity of the fluorine-containing polymer solution A-1 at 25°C was 21 cm 2 / s.

[0194] The composition of the fluorine-containing polymer 1 was CTFE unit / EVE unit / HBVE unit / CHVE unit = 50 / 25 / 10 / 15 (molar ratio).

[0195] [Synthesis Example 2]

[0196] Into a stainless steel pressure reactor with a content volume of 2500 ml equipped with a stirrer, 10 g of potassium carbonate, 156 g of ethanol, 623 g of a mixed solvent of xylene / ethylbenzene, 26 g of EVE, 55 g of HBVE, and 44 g of CHVE were charged, and dissolved oxygen in the liquid was removed by nitrogen-based degassing. Further, 171 g of CTFE was introduced into the above reactor and warmed. The temperature in the reactor was heated to 65°C. Thereafter, 5 ml of a 25% xylene solution of PBPV was added to the reactor, and the reaction was started.

[0197] While maintaining the reaction rate, additional monomers of 457 g of CTFE, 87 g of EVE, 149 g of CHVE, and 183 g of HBVE were continuously added to the reactor, and a 25% xylene solution of PBPV as a radical polymerization initiator was intermittently added to the reactor, and the polymerization was performed. The total amount of the 25% xylene solution of PBPV intermittently added to the reactor after the start of the polymerization was 30 ml. After 16 hours, the reactor was water-cooled to stop the reaction.

[0198] After the reaction liquid was cooled to room temperature, 0.1 g of hydroquinone monomethyl ether (hereinafter also referred to as HQMME) was added, unreacted monomers were purged, and insoluble components of the resulting reaction liquid were removed by filtration. Further, after removing ethanol by reduced pressure distillation, concentration adjustment was performed so that the solid content concentration became 65%, and a fluorine-containing polymer solution was obtained.

[0199] In addition, 3.5 g of a compound containing a piperidyl group (manufactured by BASF Corporation, trade name "TINUVIN 144", bis(l,2,2,6,6-pentamethyl-4-piperidyl)[[3,5-bis(l,l-dimethylethyl)-4-hydroxyphenyl]methyl]butylmalonate) was added and stirred until dissolved, and a fluorine-containing polymer solution A-2 containing the fluorine-containing polymer 2 was obtained. The viscosity of the fluorine-containing polymer solution A-2 at 25°C was 15 cm 2 / s.

[0200] The composition of the fluorine-containing polymer 2 was CTFE unit / EVE unit / HBVE unit / CHVE unit = 50 / 15 / 20 / 15 (molar ratio).

[0201] [Synthesis Example 3]

[0202] Into a stainless steel pressure-resistant reactor with a content volume of 2500 ml equipped with a stirrer, 20 g of a piperidyl group-containing compound (manufactured by BASF Corporation, trade name "TINUVIN 292", a mixture of bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and 1,2,2,6,6-pentamethyl-4-piperidyl sebacate methyl ester (mass ratio 3:1) ), 20 g of a hydrotalcite (manufactured by Kyowa Chemical Industry Co., Ltd., trade name "KW500", particle size 45 μm or less: 38%, particle size 45 to 75 μm: 35%, particle size 75 to 106 μm: 21%, particle size 106 to 500 μm: 6%), 679 g of a mixed solvent of xylene / ethylbenzene, 118 g of HBVE, and 453 g of CHVE were charged, and dissolved oxygen in the liquid was removed by nitrogen-based degassing. Further, 536 g of CTFE was introduced into the above reactor and warmed. The temperature in the reactor was heated to 65°C. Thereafter, 2 ml of a 5% xylene solution of PBPV was added to the reactor, and the reaction was started.

[0203] While maintaining the reaction rate, 110 g of CTFE, 93 g of CHVE, and 24 g of HBVE were continuously added to the reactor as additional monomers, and a 5% xylene solution of PBPV as a radical polymerization initiator was intermittently added to the reactor, and polymerization was performed. The total amount of the 5% xylene solution of PBPV intermittently added to the reactor after the start of polymerization was 55 ml. After 16 hours, the reactor was water-cooled to stop the reaction.

[0204] After the reaction liquid was cooled to room temperature, unreacted monomers were purged, and insoluble components of the obtained reaction liquid were removed by filtration. In addition, concentration adjustment was performed so that the solid content concentration became 69%, and a fluorine-containing polymer solution A-3 containing fluorine-containing polymer 3 was obtained. The viscosity of the fluorine-containing polymer solution A-3 at 25°C was 132 cm 2 / s.

[0205] The composition of the fluorine-containing polymer 3 was CTFE unit / HBVE unit / CHVE unit = 50 / 11 / 39 (molar ratio).

[0206] [Synthesis Example 4]

[0207] The amount of the mixed xylene / ethylbenzene mixed solvent removed by distillation was adjusted so that the solid content concentration and the viscosity at 25°C of the fluorine-containing polymer solution became the values described in Table 1, and otherwise the same operation as in Synthesis Example 2 was performed, and a fluorine-containing polymer solution A-4 containing fluorine-containing polymer 4 was obtained.

[0208] The composition of the fluorine-containing polymer 4 was CTFE unit / EVE unit / HBVE unit / CHVE unit = 51 / 16 / 20 / 13 (molar ratio).

[0209] [Synthesis Example 5]

[0210] The amount of the mixed xylene / ethylbenzene mixed solvent to be distilled off was adjusted so that the solid content concentration and the viscosity at 25°C of the fluorine-containing polymer solution would become the values described in Table 1, and otherwise, the same operation as in Synthesis Example 1 was performed to obtain a fluorine-containing polymer solution A-5 containing fluorine-containing polymer 5.

[0211] The composition of fluorine-containing polymer 5 was CTFE unit / EVE unit / HBVE unit / CHVE unit = 50 / 26 / 10 / 14 (molar ratio).

[0212] [Synthesis Example 6]

[0213] The amount of the mixed xylene / ethylbenzene mixed solvent to be distilled off was adjusted so that the solid content concentration and the viscosity at 25°C of the fluorine-containing polymer solution would become the values described in Table 1, and otherwise, the same operation as in Synthesis Example 3 was performed to obtain a fluorine-containing polymer solution A-6 containing fluorine-containing polymer 6.

[0214] The composition of fluorine-containing polymer 6 was CTFE unit / HBVE unit / CHVE unit = 51 / 11 / 38 (molar ratio).

[0215] [Synthesis Example 7]

[0216] The amount of the mixed xylene / ethylbenzene mixed solvent to be distilled off was adjusted so that the solid content concentration and the viscosity at 25°C of the fluorine-containing polymer solution would become the values described in Table 1, and otherwise, the same operation as in Synthesis Example 3 was performed to obtain a fluorine-containing polymer solution A-7 containing fluorine-containing polymer 7.

[0217] The composition of fluorine-containing polymer 7 was CTFE unit / HBVE unit / CHVE unit = 50 / 11 / 39 (molar ratio).

[0218] [Table 1]

[0219]

[0220] [Manufacture of Solid Composition]

[0221] Using Figure 1 the solvent removal apparatus 1 configured as shown in the drawing, a solid composition was manufactured from each of the fluorine-containing polymer solutions. Note that, as the solvent removal apparatus 1, a device having a surface area of 0.2 m 2 was used.

[0222] Here, the internal pressure (degree of vacuum) of the housing portion 10 in the solvent removal apparatus 1 was set to 2 Torr. Further, the temperature of the heat medium (oil with alkyl diphenyl as a main component, trade name: NeoSK-OIL 290, manufactured by Soken Tecnix Co., Ltd.), the rotation speed of the stirring blade 12b, the rotation speed of the screw blade 14b, and each condition of the distance D were adjusted as described in Tables 2 and 3. Further, after the conditions of the raw material supply pump were set in such a manner that the supply amount (L / H) of the fluoropolymer solution supplied from the raw material inlet 20 became the values described in Tables 2 and 3, the fluoropolymer solution was supplied from the raw material inlet 20.

[0223] The fluoropolymer in a molten state included in the solid composition taken out from the concentrate outlet 21 was cooled and solidified to obtain solid compositions B-1 to B-12 and C-1 to C-4.

[0224] [Measurement of solid content mass]

[0225] Using the obtained solid compositions B-1 to B-12 and C-1 to C-4, the solid content mass (mass %) of each solid composition was found.

[0226] Specifically, the proportion of the mass of the residue remaining after 0.25 g of the solid composition was heated at 110°C for 3 hours using a hot air circulation type dryer with respect to 0.25 g of each solid composition before heating (solid content mass) was found. The results are shown in Tables 2 and 3.

[0227] In the case where the solid content mass is 99.0 mass% or more, it can be said that the solvent in the fluoropolymer solution can be efficiently removed.

[0228] [Table 2]

[0229]

[0230] [Table 3]

[0231]

[0232] As shown in Tables 2 and 3, according to the method for producing a solid composition of the present application, it was confirmed that the solvent in the fluoropolymer solution can be efficiently removed (Examples 1-1 to 1-6, Examples 2-1 to 2-6).

[0233] Note that the specification, claims, drawings, and abstract of Japanese Patent Application No. 2023-037887 filed on March 10, 2023 are hereby incorporated by reference in their entirety as the disclosure of the present application.

[0234] Explanation of Reference Signs

[0235] 1Solvent removal device

[0236] 10 housing part

[0237] 10a inner wall

[0238] 11Liquid distribution tray

[0239] 12a Upper rotating shaft

[0240] 12b stirring blade

[0241] 13 scraper blade

[0242] 14a lower rotating shaft

[0243] 14b screw blade

[0244] 20Raw material entrance

[0245] 21 Concentrate Export

[0246] 22 steam outlet

[0247] 30 heating jacket

[0248] 31, 32 heat medium inlet

[0249] 33, 34 heat medium outlet.

Claims

1. A method for producing a solid composition, characterized by, In the method, a solvent removal device is used to remove the solvent from a fluoropolymer solution containing a fluoropolymer and a solvent, thereby obtaining a solid composition, The solvent removal device is a device that has: a cylindrical housing portion whose inside is supplied with the fluoropolymer solution; a rotating shaft that is disposed inside the housing portion and extends along the extension direction of the housing portion; and a stirring blade that is connected to the rotating shaft, forms a film of the fluoropolymer solution on the inner wall of the housing portion using the stirring blade that rotates along with the rotation of the rotating shaft, and removes the solvent from the film of the fluoropolymer solution, the solvent contains at least one of mixed xylene and ethylbenzene, the mixed xylene containing at least two or more of o-xylene, m-xylene, and p-xylene. The viscosity of the fluorine-containing polymer solution at 25°C is 5 cm 2 / s or more and less than 35 cm 2 / s, and the shortest distance between the stirring blade and the inner wall of the housing portion, i.e., the distance D, is 3 mm or less, or The viscosity of the fluorine-containing polymer solution at 25°C is 35 cm 2 / s or more and 150 cm 2 / s or less, and the distance D is 4 to 6 mm.

2. The method of manufacturing a solid composition according to claim 1, wherein, The mixed xylene contains all of o-xylene, m-xylene, and p-xylene.

3. The method of manufacturing a solid composition according to claim 2, wherein, The mass ratio of the content of the ethylbenzene to the content of the mixed xylene is 0.1 to 7.

0.

4. The method of manufacturing a solid composition according to claim 3, wherein, The solid content concentration of the fluoropolymer solution is 40 to 90 mass%.

5. The method of manufacturing a solid composition according to claim 1 or 2, wherein, The fluoropolymer has a unit based on a fluoroolefin.

6. The method of manufacturing a solid composition according to claim 1 or 2, wherein, The fluoropolymer has a unit based on chlorotrifluoroethylene and a unit based on a vinyl ether.

7. The method of manufacturing a solid composition according to claim 1 or 2, wherein, The solvent removal device has a heating means that heats the housing portion using a heat medium, 8. The method of manufacturing a solid composition according to claim 1 or 2, wherein, The viscosity of the fluorine-containing polymer solution at 25°C is 5 cm 2 / s or more and less than 35 cm 2 / s, and the distance D is 1 to 3 mm.

9. The method of manufacturing a solid composition according to claim 1 or 2, wherein, The viscosity of the fluorine-containing polymer solution at 25°C is 35 cm 2 / s or more and 150 cm 2 / s or less, and the distance D is 5 to 6 mm.

10. The method of manufacturing a solid composition according to claim 1 or 2, wherein, The temperature of the heat medium is 90 to 140°C. The solid composition is used as a raw material for a powder paint.

11. The method of manufacturing a solid composition according to claim 1 or 2, wherein, ​

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