Fluorine-containing copolymer, composition, powder coating material, coated article, and method for producing fluorine-containing copolymer

Abstract

Provided are a fluorine-containing copolymer with which a powder coating material having excellent blocking resistance can be obtained, a method for producing a fluorine-containing copolymer, a composition, a powder coating material, and a coated article. This fluorine-containing copolymer contains a chlorotrifluoroethylene-based unit and a vinyl ether-based unit, and in the fluorine-containing copolymer, the proportion of components having a molecular weight of 1100 or less as determined from an integral molecular weight distribution curve is 0.6% or less, and the molecular weight distribution is 2.0-3.2.

Description

Technical Field

[0001] The present invention relates to a fluorine-containing copolymer, a composition, a powder coating, a coated article and a method for producing the fluorine-containing copolymer. Background Art

[0002] A coating containing a fluorinated copolymer can form a coating film having excellent weather resistance. As a method for producing such a fluorinated copolymer, Patent Document 1 discloses a method for obtaining a fluorinated copolymer using a fluoroolefin, a monomer having a crosslinking group, and a monomer having no fluorine atom and a crosslinking group in the presence of a piperidinyl-containing compound and an organic solvent.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: International Publication No. 2014 / 054545 Summary of the invention

[0006] Problem that the invention aims to solve

[0007] In the field of coatings, powder coatings that do not contain volatile organic compounds (VOC) are attracting attention from the perspective of environmental protection.

[0008] The present inventors evaluated a powder coating material containing a fluorinated copolymer obtained by the method described in Patent Document 1 and found that there is room for improvement in the anti-blocking property of the powder coating material.

[0009] The present invention aims to provide a fluorinated copolymer capable of obtaining a powder coating having excellent anti-blocking properties. In addition, the present invention aims to provide a method for producing the fluorinated copolymer, a composition and a powder coating comprising the fluorinated copolymer, and a coated article obtained by using the powder coating.

[0010] Solutions for solving problems

[0011] The present inventors have conducted intensive studies on the above-mentioned problems and, as a result, have found that a powder coating having excellent anti-blocking properties can be obtained by using a fluorinated copolymer comprising units based on chlorotrifluoroethylene and units based on vinyl ether, wherein the proportion of components having a molecular weight of 1,100 or less is 0.6% or less and the molecular weight distribution is 2.0 to 3.2, thereby completing the present invention.

[0012] That is, the inventors have found that the above-mentioned problems can be solved by the following configuration.

[0013] [1] A fluorinated copolymer comprising units based on chlorotrifluoroethylene and units based on vinyl ether, wherein the proportion of components having a molecular weight of 1,100 or less as determined from an integrated molecular weight distribution curve is at most 0.6%, and the molecular weight distribution is 2.0 to 3.2.

[0014] [2] The fluorinated copolymer according to [1], wherein the proportion of components having a molecular weight of 2,000 or less determined from the integrated molecular weight distribution curve is at most 2.80%.

[0015] [3] The fluorinated copolymer according to [1] or [2], which has a weight average molecular weight of 10,000 to 60,000.

[0016] [4] The fluorinated copolymer according to any one of [1] to [3], which has a crosslinkable group.

[0017] [5] The fluorinated copolymer according to [4], wherein the crosslinkable group is a hydroxyl group or a carboxyl group.

[0018] [6] The fluorinated copolymer according to any one of [1] to [5], wherein the content of the units derived from chlorotrifluoroethylene is 30 to 70 mol % based on the total repeating units of the fluorinated copolymer.

[0019] [7] The fluorinated copolymer according to any one of [1] to [6], wherein the vinyl ether-based unit contains a unit having a crosslinkable group,

[0020] The content of the unit having a crosslinkable group is 1 to 20 mol % based on all repeating units of the fluorinated copolymer.

[0021] [8] The fluorinated copolymer according to any one of [1] to [7], wherein the units based on vinyl ether include units having no crosslinkable group,

[0022] The content of the unit having no crosslinkable group is 1 to 70 mol % based on all repeating units of the fluorinated copolymer.

[0023] [9] A composition comprising the fluorinated copolymer according to any one of [1] to [8] and a piperidinyl group-containing compound.

[0024]

[10] A composition comprising the fluorinated copolymer according to any one of [1] to [8] and a solvent.

[0025]

[11] A powder coating comprising the fluorinated copolymer according to any one of [1] to [8].

[0026]

[12] A method for producing a coated article, characterized in that the powder coating material described in

[11] is applied to a surface of a substrate to form a coating layer, and the coating layer is melted and solidified to form a coating film.

[0027]

[13] A method for producing a fluorinated copolymer, characterized in that the fluorinated copolymer comprises units based on chlorotrifluoroethylene and units based on vinyl ether, the method comprising the following steps: polymerizing in a reactor in the presence of the chlorotrifluoroethylene, the vinyl ether, a solvent and a radical polymerization initiator to produce the fluorinated copolymer; after starting the polymerization, continuously or intermittently supplying a mixture of the chlorotrifluoroethylene and the vinyl ether to the reactor; in the reactor before starting the polymerization, the ratio of the total molar amount of the chlorotrifluoroethylene and the molar amount of the vinyl ether to the molar amount of the solvent is 0.30 or more; and the molar ratio A of the vinyl ether to the chlorotrifluoroethylene in the reactor before starting the polymerization and the molar ratio B of the vinyl ether to the chlorotrifluoroethylene in the mixture satisfy the following relationship.

[0028] 0.5≤A / B≤1.5

[0029]

[14] The method for producing a fluorinated copolymer according to

[13] , wherein the molar ratio of the total molar amount of the chlorotrifluoroethylene and the vinyl ether in the reactor before starting the polymerization to the total amount of the chlorotrifluoroethylene and the vinyl ether used in the production of the fluorinated copolymer is 0.3 or more.

[0030]

[15] The method for producing a fluorinated copolymer according to

[13] or

[14] , wherein the polymerization is carried out in the presence of a piperidinyl group-containing compound.

[0031] Effects of the Invention

[0032] According to the present invention, a fluorinated copolymer capable of obtaining a powder coating having excellent anti-blocking properties can be provided. In addition, the present invention can also provide a method for producing the fluorinated copolymer, a composition and a powder coating comprising the fluorinated copolymer, and a coated article obtained by using the powder coating. DETAILED DESCRIPTION

[0033] The meanings of the terms in the present invention are as follows.

[0034] The numerical range represented by "~" refers to a range including the numerical values ​​recorded before and after "~" as the lower limit and the upper limit. In the numerical range recorded in stages in this specification, the upper limit or lower limit recorded in a certain numerical range can be replaced by the upper limit or lower limit of the numerical range recorded in other stages. In addition, in the numerical range recorded in this specification, the upper limit or lower limit recorded in a certain numerical range can be replaced by the value shown in the embodiment.

[0035] In this specification, for each component, the substance belonging to each component can be used alone or in combination of two or more. Here, when two or more substances are used in combination for each component, the content of the component, unless otherwise specified, refers to the total content of the substances used in combination.

[0036] In the present specification, a combination of two or more preferred aspects is a more preferred aspect.

[0037] Unit refers to the general term for the atomic group based on one molecule of the above monomer formed directly by polymerization of the monomer and the atomic group obtained by chemical conversion of a part of the above atomic group. The content (mol %) of each unit relative to all units contained in the polymer can be obtained by analyzing the polymer using nuclear magnetic resonance spectroscopy, or it can be determined by the input amount of the components used in the manufacture of the polymer.

[0038] (Meth)acrylic acid is a general term for acrylic acid and methacrylic acid.

[0039] The hydrolyzable silyl group refers to a group that can undergo a hydrolysis reaction to form a silanol group.

[0040] The acid value and the hydroxyl value are values ​​measured according to the method of JIS K0070-3 (1992), respectively.

[0041] The glass transition temperature (Tg) is the midpoint glass transition temperature of a polymer as measured by differential scanning calorimetry (DSC).

[0042] The melt viscosity is a value of the melt viscosity of a sample at 170° C. when the temperature is increased from 130° C. to 200° C. at a temperature increase rate of 10° C. / min using a rotational rheometer.

[0043] The number average molecular weight (Mn) and the weight average molecular weight (Mw) are values ​​measured by size exclusion chromatography (gel permeation chromatography) using polystyrene as a standard substance. In addition, the ratio of Mw to Mn represents the molecular weight distribution and is also referred to as Mw / Mn.

[0044] The average particle size of the particles is a value of 50% diameter obtained by calculating the volume average from the particle size distribution measured using a known particle size distribution measuring apparatus (Sympatec trade name Helos-Rodos, etc.) based on the measurement principle of laser diffraction.

[0045] The film thickness is a value measured using an eddy current film thickness meter (SANKO ELECTRONIC LABORATORY CO., LTD. trade name EDY-5000, etc.).

[0046] The fluorinated copolymer of the present invention (hereinafter also referred to as a specific fluorinated copolymer) is a fluorinated copolymer comprising units based on chlorotrifluoroethylene and units based on vinyl ether, and in an integrated molecular weight distribution curve obtained by measuring the above fluorinated copolymer by gel permeation chromatography, the proportion of components with a molecular weight of 1100 or less is less than 0.6%, and the molecular weight distribution is 2.0 to 3.2.

[0047] When the specific fluorinated copolymer is used, a powder coating material having excellent anti-blocking properties can be obtained. The reason for this is not clear, but it is considered as follows.

[0048] The low molecular weight component with a molecular weight of 1100 or less is the main factor that reduces the Tg of the fluorinated copolymer. If the Tg of the fluorinated copolymer is reduced, blocking is likely to occur when it is made into a powder coating. It is speculated that the specific fluorinated copolymer has a small content of low molecular weight components, so a powder coating with excellent anti-blocking properties is obtained.

[0049] The specific fluorine-containing copolymer comprises a unit based on chlorotrifluoroethylene (CF2=CFCl) and a unit based on vinyl ether.

[0050] The specific fluorinated copolymer preferably has a crosslinkable group from the viewpoint of being able to further improve the hardness of a coating film obtained using a powder coating material containing the specific fluorinated copolymer.

[0051] Specific examples of the crosslinking group include at least one group selected from the group consisting of a hydroxyl group, an amino group, an epoxy group, an oxetane group, a decomposable silyl group, a sulfo group, and a carboxyl group. From the perspective of further improving the hardness of the coating film obtained using the powder coating, a hydroxyl group or a carboxyl group is preferred, and a hydroxyl group is more preferred. It should be noted that the sulfo group and the carboxyl group can be ionized to form -SO3 - or -COO - , can also be salted to become -SO3 - Na + or -COO - Na + wait.

[0052] The number of the crosslinkable groups may be 1 or 2 or more. Two or more crosslinkable groups may be used in combination.

[0053] The content of the units based on chlorotrifluoroethylene is preferably 30 to 70 mol %, more preferably 40 to 60 mol %, further preferably 45 to 55 mol %, based on the total repeating units of the specific fluorinated copolymer, from the viewpoint that the weather resistance of a coating film obtained by using a powder coating material comprising the specific fluorinated copolymer is more excellent.

[0054] The vinyl ether may be a vinyl ether having a crosslinkable group or a vinyl ether not having a crosslinkable group. Specific examples of the crosslinkable group are as described above.

[0055] The vinyl ethers may be used in combination of two or more kinds. Among them, a combination of a vinyl ether having a crosslinkable group and a vinyl ether not having a crosslinkable group is preferred.

[0056] The vinyl ether may or may not have a fluorine atom, but preferably does not have a fluorine atom.

[0057] As the vinyl ether having a crosslinkable group, vinyl ether having a hydroxyl group and vinyl ether having a carboxyl group are preferred, and vinyl ether having a hydroxyl group is more preferred, since the hardness of a coating film obtained by using a powder coating material containing the specific fluorinated copolymer can be further improved.

[0058] Specific examples of vinyl ethers having a hydroxyl group include CH2=CHO-CH2-cycloC6H 10 -CH2OH, CH2=CHOCH2CH2OH, CH2=CHOCH2CH2CH2CH2OH.

[0059] It should be noted that "-cycloC6H 10 -" represents cyclohexylene, "-cycloC6H 10 -" is usually a 1,4-bonding site.

[0060] The vinyl ethers having a hydroxyl group may be used in combination of two or more types.

[0061] Specific examples of vinyl ethers having a carboxyl group include CH2=CHO(CH2) n12 A monomer represented by OC(O)CH2CH2COOH (wherein n12 represents an integer from 1 to 10).

[0062] The vinyl ethers having a carboxyl group may be used in combination of two or more.

[0063] Specific examples of the vinyl ether having no crosslinkable group include ethyl vinyl ether, tert-butyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexyl vinyl ether, and cyclohexyl methyl vinyl ether.

[0064] The vinyl ethers having no crosslinkable group may be used in combination of two or more.

[0065] The content of the units based on vinyl ether is preferably from 1 to 80 mol %, more preferably from 10 to 70 mol %, further preferably from 20 to 60 mol %, based on all repeating units of the specific fluorinated copolymer.

[0066] In a case where the units based on vinyl ether include units based on vinyl ether having a crosslinkable group, the content of the units based on vinyl ether having a crosslinkable group is preferably 1 to 20 mol %, more preferably 3 to 20 mol %, further preferably 5 to 15 mol % based on all repeating units of the specific fluorinated copolymer, from the viewpoint of being able to further improve the hardness of a coating film obtained by using a powder coating material comprising the specific fluorinated copolymer.

[0067] In a case where the units based on vinyl ether include units based on vinyl ether having no crosslinking group, the content of the units based on vinyl ether having no crosslinking group is preferably 1 to 70 mol %, more preferably 5 to 60 mol %, further preferably 10 to 50 mol % based on all repeating units of the specific fluorinated copolymer, from the viewpoint of being able to further improve the smoothness of a coating film obtained by using a powder coating material comprising the specific fluorinated copolymer.

[0068] The specific fluorinated copolymer may contain units other than the units based on chlorotrifluoroethylene and the units based on vinyl ether (hereinafter also referred to as other units), but preferably contains substantially no other units from the viewpoint that a coating film obtained using a powder coating material containing the specific fluorinated copolymer has more excellent weather resistance.

[0069] Here, substantially containing no other units means that the content of other units is at most 0.1 mol % based on all repeating units of the specific fluorinated copolymer.

[0070] Specific examples of other units include units based on fluoroolefins other than chlorotrifluoroethylene and units based on vinyl esters.

[0071] The specific fluorinated copolymer preferably has no carboxyl group from the viewpoint of further improving the hardness of a coating film obtained by using a powder coating material comprising the specific fluorinated copolymer. In this case, the specific fluorinated copolymer preferably has a hydroxyl group.

[0072] The specific fluorinated copolymer preferably contains 30 to 70 mol %, 1 to 20 mol % and 1 to 70 mol % of units based on chlorotrifluoroethylene, 1 to 20 mol % and 1 to 70 mol % of units based on vinyl ether having a crosslinkable group, respectively, based on all the units contained in the specific fluorinated copolymer, and more preferably contains 45 to 55 mol %, 5 to 15 mol % and 10 to 50 mol % of units based on vinyl ether having no crosslinkable group, respectively.

[0073] The Tg of the specific fluorinated copolymer is preferably from 30 to 60°C, more preferably from 35 to 60°C, further preferably from 40 to 55°C, from the viewpoint of further improving the anti-blocking property of the present coating material and the surface smoothness of the present coating film.

[0074] The Tg of the specific fluorinated copolymer is preferably from 51.5 to 55°C, since the surface smoothness of the coating film obtained by baking at a high temperature of about 200°C can be further improved.

[0075] The Tg of the specific fluorinated copolymer is preferably from 39 to 51°C, since the smoothness of a coating film obtained by baking at a low temperature of about 170°C can be further improved.

[0076] The melt viscosity of the specific fluorinated copolymer at 170°C is preferably 10 to 450 Pa·s, more preferably 30 to 450 Pa·s, further preferably 40 to 400 Pa·s, since a coating film obtained using a powder coating material comprising the specific fluorinated copolymer has more excellent smoothness.

[0077] The melt viscosity of the specific fluorinated copolymer at 170°C is preferably from 200 to 400 Pa·s from the viewpoint of being able to further improve the surface smoothness of a coating film obtained by baking at a high temperature of about 200°C.

[0078] The melt viscosity of the specific fluorinated copolymer at 170°C is preferably from 15 to 100 Pa·s from the viewpoint of further improving the smoothness of a coating film obtained by baking at a low temperature of about 170°C.

[0079] When the specific fluorinated copolymer has a hydroxyl value, the hydroxyl value of the specific fluorinated copolymer is preferably higher than 0 mgKOH / g and lower than 150 mgKOH / g, more preferably 5 to 100 mgKOH / g, further preferably 15 to 70 mgKOH / g, particularly preferably 30 to 60 mgKOH / g.

[0080] When the specific fluorinated copolymer has an acid value, the acid value of the specific fluorinated copolymer is preferably more than 0 mgKOH / g and less than 10 mgKOH / g, more preferably 2 to 8 mgKOH / g, further preferably 3 to 7 mgKOH / g.

[0081] The Mw / Mn (molecular weight distribution) of the specific fluorinated copolymer is from 2.0 to 3.2, preferably from 2.3 to 3.2, more preferably from 2.5 to 3.1, from the viewpoint of more excellent effects of the present invention.

[0082] The Mw / Mn (molecular weight distribution) of the specific fluorinated copolymer is preferably from 3.0 to 3.2 from the viewpoint of being able to further improve the surface smoothness of a coating film obtained by baking at a high temperature of about 200°C.

[0083] The Mw / Mn (molecular weight distribution) of the specific fluorinated copolymer is preferably from 2.5 to 2.7 from the viewpoint of being able to further improve the surface smoothness of a coating film obtained by calcining at a low temperature of about 170°C.

[0084] Examples of a method for adjusting Mw / Mn of the specific fluorinated copolymer include a method of using a piperidinyl group-containing compound (described later), hydrotalcite (described later) or the like in producing the specific fluorinated copolymer, and a method of adjusting the amounts of these components.

[0085] The Mw of the specific fluorinated copolymer is preferably from 10,000 to 60,000, more preferably from 15,000 to 55,000, further preferably from 16,000 to 52,000, from the viewpoint of more excellent effects of the present invention.

[0086] The Mw of the specific fluorinated copolymer is preferably from 40,000 to 52,000, since the surface smoothness of the coating film obtained by baking at a high temperature of about 200°C can be further improved.

[0087] The Mw of the specific fluorinated copolymer is preferably from 16,000 to 41,000, since the surface smoothness of the coating film obtained by calcining at a low temperature of about 170°C can be further improved.

[0088] The Mn of the specific fluorinated copolymer is preferably from 7,000 to 20,000, more preferably from 8,000 to 18,000, further preferably from 10,000 to 17,000, from the viewpoint of more excellent effects of the present invention.

[0089] The proportion of components having a molecular weight of 1100 or less in the specific fluorinated copolymer obtained from the integrated molecular weight distribution curve (hereinafter also referred to as proportion M1) is 0.6% or less, preferably 0.58% or less, more preferably 0.55% or less, from the perspective of achieving a more excellent effect of the present invention. The lower limit of proportion M1 is usually 0%.

[0090] The proportion of the components having a molecular weight of 2000 or less in the specific fluorinated copolymer obtained from the integrated molecular weight distribution curve (hereinafter referred to as proportion M2) is preferably 3.00% or less, more preferably 2.80% or less, from the viewpoint of more excellent effects of the present invention. The lower limit of proportion M2 is usually 0%.

[0091] When the method for producing a fluorinated copolymer described later is adopted, a specific fluorinated copolymer having the ratio M1 and the ratio M2 within the above range can be easily obtained.

[0092] Here, the integrated molecular weight distribution curve is obtained as follows.

[0093] First, gel permeation chromatography is used to obtain a dissolution curve (chromatogram) of a specific fluorinated copolymer obtained from the dissolution time and the detection intensity based on an RI (differential refractometer). A baseline is drawn on the obtained dissolution curve to determine the peak of the specific fluorinated copolymer. Here, the baseline is a straight line parallel to the axis of the dissolution time at a position where the detection intensity of the peak of the specific fluorinated copolymer is 1 / 20.

[0094] Next, the dissolution time is converted into molecular weight using a calibration curve (standard curve), the peak area (regional area) of the dissolution curve is obtained, the concentration fraction at each dissolution time is calculated, and then the concentration fractions are accumulated. The logarithmic value of the molecular weight is plotted on the horizontal axis and the cumulative value (%) of the concentration fraction is plotted on the vertical axis, thereby obtaining an integrated molecular weight distribution curve of the specific fluorinated copolymer.

[0095] The ratio M1 corresponds to the value of the vertical axis (cumulative value of concentration fraction) at the point corresponding to the molecular weight of 1100 on the integrated molecular weight distribution curve. The ratio M2 corresponds to the value of the vertical axis (cumulative value of concentration fraction) at the point corresponding to the molecular weight of 2000 on the integrated molecular weight distribution curve.

[0096] The specific fluorinated copolymer can be used as a component of a coating. The coating prepared from the specific fluorinated copolymer may be any of a solvent-based coating in which the specific fluorinated copolymer is dissolved in an organic solvent, an aqueous coating in which the specific fluorinated copolymer is dispersed in water, and a powder coating containing a specific fluorinated copolymer powder, preferably a powder coating.

[0097] The specific fluorinated copolymer is preferably produced by the method for producing a fluorinated copolymer described below, from the viewpoint of easily obtaining a fluorinated copolymer having the ratio M1 and the molecular weight distribution adjusted within the above ranges.

[0098] The method for producing a fluorinated copolymer of the present invention (hereinafter also referred to as the present production method) is a method for producing a fluorinated copolymer comprising units based on chlorotrifluoroethylene and units based on vinyl ether.

[0099] The production method comprises the following steps: performing polymerization in a reactor in the presence of the above-mentioned chlorotrifluoroethylene, the above-mentioned vinyl ether, a solvent and a radical polymerization initiator to produce a fluorinated copolymer;

[0100] After the polymerization is started, the mixture of chlorotrifluoroethylene and vinyl ether is continuously or intermittently supplied to the reactor.

[0101] In the reactor before starting the polymerization, the ratio of the total molar amount of the chlorotrifluoroethylene and the molar amount of the vinyl ether to the molar amount of the solvent is 0.30 or more.

[0102] The molar ratio A of the vinyl ether to the chlorotrifluoroethylene in the reactor before the start of the polymerization and the molar ratio B of the vinyl ether to the chlorotrifluoroethylene in the mixture satisfy the following relationship.

[0103] 0.5≤A / B≤1.5

[0104] According to this production method, the above-mentioned specific fluorinated copolymer can be easily produced.

[0105] The chlorotrifluoroethylene and vinyl ether used in the present production method are as described in the above-mentioned specific fluorinated copolymer, and the preferred embodiments are also the same.

[0106] In the present production method, monomers other than chlorotrifluoroethylene and vinyl ether may be used. However, from the viewpoint of achieving more excellent effects of the present invention, it is preferred to use only chlorotrifluoroethylene and vinyl ether as monomers.

[0107] Examples of the solvent (polymerization solvent) used in the present production method include organic solvents, water, and mixed solvents thereof. An organic solvent is preferred because the production of the fluorinated copolymer is easy.

[0108] The organic solvent is preferably one or more organic solvents selected from the group consisting of aromatic hydrocarbon solvents, ketone solvents, ester solvents, alcohol solvents, and ether ester solvents.

[0109] Specific examples of aromatic hydrocarbon solvents include toluene, xylene, ethylbenzene, aromatic naphtha, tetralin, and turpentine. Commercially available aromatic hydrocarbon solvents may be used, and Solvesso (registered trademark) #100 (manufactured by Exxon Chemical Company), Solvesso (registered trademark) #150 (manufactured by Exxon Chemical Company), etc. may also be used.

[0110] Specific examples of the ketone solvent include acetone, methyl ethyl ketone, methyl amyl ketone, methyl isobutyl ketone, ethyl isobutyl ketone, diisobutyl ketone, cyclohexanone, and isophorone.

[0111] Specific examples of the ester solvent include methyl acetate, ethyl acetate, n-propyl acetate, isobutyl acetate, and tert-butyl acetate.

[0112] Specific examples of the alcohol solvent include ethanol, tert-butyl alcohol, and isopropyl alcohol.

[0113] Specific examples of the ether ester solvent include ethyl 3-ethoxypropionate, propylene glycol monomethyl ether acetate, and methoxybutyl acetate.

[0114] Two or more organic solvents may be used in combination.

[0115] Examples of the radical polymerization initiator include peroxide-based initiators and azo-based initiators.

[0116] Specific examples of the peroxide-based initiator include cyclohexanone peroxide, tert-butyl hydroperoxide, dibenzoyl peroxide, di-tert-butyl peroxide, 2,2-di(tert-butylperoxy)butane, tert-butyl peroxypivalate, and diisopropyl peroxydicarbonate.

[0117] Specific examples of the azo initiator include 2,2′-azobisisobutyronitrile, 1,1′-azobiscyclohexane-1-carbonitrile, 2,2′-azobis(2,4-dimethylvaleronitrile), and 2,2′-azobis(2-methylbutyronitrile).

[0118] The radical polymerization initiators may be used in combination of two or more.

[0119] In the present production method, after the polymerization of chlorotrifluoroethylene and vinyl ether initially introduced into the reactor is initiated, a mixture of chlorotrifluoroethylene and vinyl ether is continuously or intermittently supplied into the reactor.

[0120] Thereby, the concentrations of chlorotrifluoroethylene and vinyl ether in the reactor can be easily kept constant, so that the proportion of low molecular weight components (components having a molecular weight of 1,100 or less) contained in the obtained fluorinated copolymer can be reduced.

[0121] Here, the type of the vinyl ether initially charged into the reactor is the same as the type of the vinyl ether added after the start of the polymerization.

[0122] As the starting time point of the above-mentioned polymerization, the time point when the temperature of the reactor containing chlorotrifluoroethylene, vinyl ether, solvent and free radical polymerization initiator is raised to the 10-hour half-life temperature of the free radical polymerization initiator can be set as the starting time point of the polymerization, or the following time point can be set as the starting time point of the polymerization: after the temperature of the reactor containing chlorotrifluoroethylene, vinyl ether and solvent but not free radical polymerization initiator is raised to the 10-hour half-life temperature of the free radical polymerization initiator, the free radical polymerization initiator is added to the reactor maintained at this temperature.

[0123] The above mixture can be added to the reactor after the start time of the above polymerization.

[0124] In the present production method, continuously supplying the mixture refers to a method of adding the mixture without interruption within a predetermined period, and refers to a method of not adding the mixture outside the predetermined period.

[0125] In the present production method, intermittently supplying the mixture is a method of adding the mixture intermittently in batches, and refers to a method of alternately repeating a period of adding the mixture and a period of not adding the mixture, and adding the mixture two or more times.

[0126] The polymerization temperature is preferably 50 to 90° C., more preferably 60 to 80° C. The polymerization pressure is preferably 0.3 to 0.8 MPa, more preferably 0.4 to 0.7 MPa. The polymerization time is preferably 0.5 to 30 hours, more preferably 1 to 20 hours.

[0127] In the reactor before starting the polymerization, the ratio of the total molar amount Mm of the molar amount of chlorotrifluoroethylene and the molar amount of vinyl ether to the molar amount Ms of the solvent (Mm / Ms) is 0.30 or more, preferably 0.50 or more, more preferably 0.65 or more. Thus, the polymerization is started while the monomer concentration in the reactor is kept high, so that the polymer chain is well extended, and the proportion of low molecular weight components (components with a molecular weight of 1100 or less) contained in the obtained fluorinated copolymer becomes small.

[0128] From the viewpoint of smoothness of the coating film, the ratio (Mm / Ms) is preferably 1.50 or less, more preferably 1.45 or less.

[0129] In the present production method, the ratio (A / B) of the molar ratio A of vinyl ether to chlorotrifluoroethylene in the reactor before the start of polymerization to the molar ratio B of vinyl ether to chlorotrifluoroethylene in the mixture is 0.5 to 1.5, preferably 0.7 to 1.3, more preferably 0.9 to 1.1. When the ratio (A / B) is within the above range, the proportion of low molecular weight components (components with a molecular weight of 1100 or less) contained in the obtained fluorinated copolymer becomes small.

[0130] The molar ratio A is preferably 0.5 to 1.5, more preferably 0.7 to 1.3, and still more preferably 0.9 to 1.1.

[0131] The molar ratio B is preferably 0.7 to 2.0, more preferably 0.8 to 1.4, and even more preferably 0.9 to 1.1.

[0132] The molar ratio (Mm / Ma) of the total molar amount Mm of chlorotrifluoroethylene and vinyl ether in the reactor before the start of polymerization to the total amount Ma of chlorotrifluoroethylene and vinyl ether used in the production of the specific fluorinated copolymer is preferably 0.3 or more, more preferably 0.5 or more, and further preferably 0.7 or more. When the molar ratio (Mm / Ma) is 0.3 or more, the anti-blocking property is more excellent.

[0133] The molar ratio (Mm / Ma) is preferably 1.0 or less, more preferably 0.8 or less, and further preferably 0.6 or less. When the molar ratio (Mm / Ma) is 1.0 or less, the smoothness of the coating film is more excellent.

[0134] The total amount of chlorotrifluoroethylene used in the polymerization is preferably 30 to 70 mol%, more preferably 45 to 55 mol%, based on the total molar amount of all monomers (the total molar amount of all monomers used in the polymerization).

[0135] The total amount of the vinyl ether used in the polymerization is preferably 1 to 80 mol%, more preferably 20 to 60 mol%, based on the total molar amount of all monomers.

[0136] When the above-mentioned vinyl ether having a crosslinkable group is used as the vinyl ether, the total amount of the vinyl ether having a crosslinkable group used in the polymerization is preferably 1 to 20 mol %, more preferably 5 to 15 mol % based on the total molar amount of all monomers.

[0137] When the vinyl ether having no crosslinkable group is used as the vinyl ether, the total amount of the vinyl ether having no crosslinkable group used in the polymerization is preferably 1 to 70 mol %, more preferably 10 to 50 mol % based on the total molar amount of all monomers.

[0138] The radical polymerization initiator may be added to the reactor before the start of polymerization, or may be continuously or intermittently supplied to the reactor after the start of polymerization of chlorotrifluoroethylene and vinyl ether initially added.

[0139] The total amount of the radical polymerization initiator used in the polymerization is preferably 0.05 to 1.5 mol%, more preferably 0.1 to 1.0 mol%, based on the total molar amount of all monomers.

[0140] In the present production method, since a solvent is used in the polymerization, a mixed liquid containing the fluorinated copolymer and the solvent may be obtained. In this case, the present production method may further include a step of removing the solvent from the mixed liquid.

[0141] Specific examples of the method for removing the solvent from the mixed liquid include heating and distillation.

[0142] In the present production method, the polymerization of chlorotrifluoroethylene and vinyl ether is preferably carried out in the presence of at least one of a piperidinyl-containing compound and a hydrotalcite, and more preferably in the presence of both a piperidinyl-containing compound and a hydrotalcite. Thus, the polymerization proceeds well, and thus the molecular weight distribution of the obtained fluorinated copolymer can be further reduced.

[0143] The piperidinyl group-containing compound refers to a compound containing a piperidinyl group or a piperidinyl group having a substituent, and more preferably a compound containing a piperidinyl group having a substituent.

[0144] The piperidinyl group having a substituent is preferably a tetra-substituted piperidinyl group, and more preferably a 2,2,6,6-tetra-substituted piperidinyl group.

[0145] The piperidinyl group-containing compound is preferably a piperidinyl group-containing compound containing two or more piperidinyl groups or a piperidinyl group having a substituted group.

[0146] It is preferable to use 2 or more types of the piperidinyl group-containing compound.

[0147] The piperidinyl group-containing compound is preferably a compound represented by the following formula (a compound having a 2,2,6,6-tetrasubstituted piperidinyl group).

[0148]

[0149] R 11 ~R 14 Each is independently an alkyl group having 1 to 18 carbon atoms (such as methyl, ethyl, propyl, dodecyl, and stearyl), a cycloalkyl group (such as cyclopentyl and cyclohexyl), a substituted alkyl group (such as 2-hydroxyethyl, 2-methoxycarbonylethyl, and 3-hydroxypropyl), an aryl group (such as phenyl and naphthyl), or an aralkyl group (such as phenethyl and benzyl), R 11 and R 12 , or R 13 and R 14 It can form an aliphatic ring having 3 to 6 carbon atoms. 11 ~R 14 In view of price and availability, an alkyl group having 1 to 18 carbon atoms is preferred, and a methyl group is particularly preferred.

[0150] R 15 It is a hydrogen atom, an alkyl group (methyl, ethyl, propyl, butyl, dodecyl, stearyl, etc.), a substituted alkyl group (2-hydroxyethyl, 2-methoxycarbonylethyl, 2-acetoxyethyl, 2-(3-methoxycarbonylpropionyloxy)ethyl, 3-hydroxypropyl, etc.), an aryl group (phenyl, naphthyl, hydroxyphenyl, etc.), an aralkyl group (phenethyl, benzyl, hydroxyphenylalkyl, etc.) or a cycloalkyl group (cyclohexyl, etc.).

[0151] R 16is a hydrogen atom, a hydroxyl group, an alkyl group (methyl, ethyl, propyl, butyl, dodecyl, stearyl, etc.), a substituted alkyl group (2-hydroxyethyl, 2-methoxycarbonylethyl, 2-acetoxyethyl, 2-(3-methoxycarbonylpropionyloxy)ethyl, 3-hydroxypropyl, etc.), an aryl group (phenyl, naphthyl, etc.), an aralkyl group (phenethyl, benzyl, etc.), a group containing an ester bond (acetoxy, propionyloxy, butyryloxy, lauroyloxy, substituted alkylcarbonyloxy, benzoyloxy, substituted benzoyloxy, etc.), a group containing an amino group (alkoxycarbonylamino, N-monoalkylcarbamoylamino, N,N-dialkylcarbamoylamino, etc.), or a group containing a 2,2,6,6-tetrasubstituted piperidinyl group. For R 16 , these groups may be combined with two or more kinds.

[0152] Specific examples of the piperidinyl group-containing compound include 2,2,6,6-tetramethylpiperidine, 1,2,2,6,6-pentamethylpiperidine, 4-hydroxy-2,2,6,6-tetramethylpiperidine, 4-hydroxy-1,2,2,6,6-pentamethylpiperidine, 1-ethyl-2,2,6,6-tetramethylpiperidine, 1-ethyl-4-hydroxy-2,2,6,6-tetramethylpiperidine, 1-butyl-4-hydroxy-2,2,6,6-tetramethylpiperidine, 1-dodecyl-2,2,6,6-tetramethylpiperidine, 1-phenyl-2,2,6,6-tetramethylpiperidine, 1-(2-hydroxyethyl)-2,2,6,6-tetramethylpiperidine, 1-(6-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidine, 4-acetoxy-2,2,6,6-tetramethylpiperidine, and 4-acetoxy- 1,2,2,6,6-pentamethylpiperidine, 1-(2-acetoxyethyl)-4-acetoxy-2,2,6,6-tetramethylpiperidine, 1-(2-benzoyloxyethyl)-4-benzoyloxy-2,2,6,6-tetramethylpiperidine, 4-ethyl-2,2,6,6-tetramethylpiperidine, 4-ethyl-1,2,2,6,6-pentamethylpiperidine, 4-butyl-2,2,6,6- Tetramethylpiperidine, 4-octyl-2,2,6,6-tetramethylpiperidine, 4-dodecyl-2,2,6,6-tetramethylpiperidine, 4-stearyl-2,2,6,6-tetramethylpiperidine, 4-stearyl-1,2,2,6,6-pentamethylpiperidine, methyl 1,2,2,6,6-pentamethyl-4-piperidinyl sebacate, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate.

[0153] As R 16Examples of the piperidinyl group-containing compound that is a group containing a 2,2,6,6-tetrasubstituted piperidinyl group include piperidinyl group-containing compounds containing two or more 2,2,6,6-tetramethylpiperidinyl groups in one molecule obtained by reacting 2,2,6,6-tetramethylpiperidine (4-hydroxy-2,2,6,6-tetramethylpiperidine, 4-hydroxy-1,2,2,6,6-pentamethylpiperidine, 1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidine, 1-(2-hydroxyethyl)-2,2,6,6-tetramethylpiperidine, etc.) having a hydroxyl group with a polybasic acid (succinic acid, adipic acid, sebacic acid, azelaic acid, decane-1,10-dicarboxylic acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, malonic acid, substituted malonic acid, etc.), and specifically include compounds represented by the following formula.

[0154] Here, n3 is an integer from 1 to 20.

[0155]

[0156] When a piperidinyl-containing compound is used in the polymerization, the ratio of the molar amount of the piperidinyl group in the piperidinyl-containing compound to the total molar amount of all monomers (the total molar amount of all monomers used in the polymerization) is preferably 0.0010 to 0.0100, more preferably 0.0032 to 0.0080. When the above ratio is within the above range, the molecular weight distribution of the obtained fluorinated copolymer can be further reduced. In addition, when the above ratio is 0.0032 or more, the thermal stability of the obtained fluorinated copolymer is excellent. When the above ratio is 0.0080 or less, the coloring of the obtained fluorinated copolymer can be suppressed.

[0157] Hydrotalcite refers to a layered double hydroxide represented by the following formula.

[0158] [Mg 2+ 1-x Al 3+ x (OH)2] x+ [CO3 2- x / 2 ·mH2O] x-

[0159] Wherein, x is 0.2~0.33, and m is 0~2.

[0160] From the perspective of excellent chloride ion adsorption and easy availability, the hydrotalcite is preferably Mg6Al2(OH) 16 CO3·4H2O (in the above formula representing hydrotalcite, x=0.25, m=0.5), or Mg 4.5 Al2(OH) 13 CO3·3.5H2O (in the above formula representing hydrotalcite, x=0.308, m=0.538).

[0161] Two or more types of hydrotalcites may be used.

[0162] The particle size of the hydrotalcite is preferably 5 to 500 μm, more preferably 5 to 110 μm. When the particle size of the hydrotalcite is 5 μm or more, removal by filtration becomes easy. When the particle size of the hydrotalcite is 500 μm or less, the surface area per unit mass is large, and the effect of the hydrotalcite is further exerted.

[0163] The particle size of the hydrotalcite is measured in accordance with JIS K 0069 "Sieve Test Methods for Chemicals".

[0164] When hydrotalcite is used in the polymerization, the mass ratio of the amount of hydrotalcite used to the total mass of all monomers (the total mass of all monomers used in the polymerization) is preferably 0.005 to 0.025, more preferably 0.010 to 0.020. When the above ratio is within the above range, the molecular weight distribution of the obtained fluorinated copolymer can be further reduced.

[0165] When the piperidinyl-containing compound and the hydrotalcite are used in the polymerization, the mass ratio of the amount of the hydrotalcite to the amount of the piperidinyl-containing compound is preferably 0.30 to 4.60, more preferably 0.50 to 1.50. When the above ratio is within the above range, the molecular weight distribution of the obtained fluorinated copolymer can be further reduced, and the coating film obtained using the fluorinated copolymer has excellent glossiness.

[0166] When hydrotalcite is used in the polymerization in the present production method, a mixed solution containing the fluorinated copolymer, the solvent and the insoluble components derived from the hydrotalcite may be obtained. In this case, the present production method may further include a step of removing the insoluble components from the mixed solution.

[0167] Specific examples of the method for removing the insoluble component include solid-liquid separation treatment such as filtration.

[0168] In the present production method, components such as a chain extender, a polymerization inhibitor, and a stabilizer may be used as necessary.

[0169] The composition of the present invention (hereinafter, also referred to as the present composition) contains a specific fluorinated copolymer and contains at least one of a solvent and a piperidinyl group-containing compound.

[0170] The content of the specific fluorinated copolymer is preferably from 5 to 99.5 mass%, more preferably from 10 to 99 mass%, based on the total mass of the present composition.

[0171] The solvent may be the polymerization solvent used for polymerization of the specific fluorinated copolymer, may be a solvent other than the polymerization solvent, or may be a mixed liquid of the polymerization solvent and a solvent other than the polymerization solvent.

[0172] Specific examples of the solvent include the solvents exemplified in the above-mentioned method for producing the fluorinated copolymer.

[0173] When the present composition contains a solvent, the content of the solvent is preferably 10 to 95% by mass, more preferably 20 to 90% by mass, based on the total mass of the present composition.

[0174] The piperidinyl group-containing compound is preferably the piperidinyl group-containing compound exemplified in the above-mentioned method for producing the fluorinated copolymer.

[0175] When the present composition contains a piperidinyl group-containing compound, the content of the piperidinyl group-containing compound is preferably from 0.3 to 2.6 mass%, more preferably from 0.8 to 2.0 mass%, based on the total mass of the specific fluorinated copolymer.

[0176] The present composition may further contain ingredients other than those listed above.

[0177] The present composition is preferably used for the production of a powder coating material described below. When the present composition contains a solvent, it may be used for the production of a powder coating material after removing the solvent.

[0178] The powder coating material of the present invention (hereinafter also referred to as the present coating material) contains a specific fluorinated copolymer.

[0179] The content of the specific fluorinated copolymer is preferably from 30 to 100 mass %, more preferably from 40 to 100 mass %, based on the total mass of the coating material.

[0180] The present coating material may contain a piperidinyl group-containing compound. The piperidinyl group-containing compound is preferably a piperidinyl group-containing compound exemplified in the above-mentioned method for producing a fluorinated copolymer.

[0181] When the present coating material contains a piperidinyl group-containing compound, the content of the piperidinyl group-containing compound is preferably 0.10 to 2.6% by mass, more preferably 0.15 to 2.0% by mass, based on the total mass of the present coating material.

[0182] The coating may also contain additives.

[0183] Specific examples of additives include pigments, curing agents, catalysts (curing catalysts, etc.), polymers other than the above (for example, polyester resins, (meth) acrylic resins, epoxy resins), fillers (resin beads, etc.), light stabilizers, ultraviolet absorbers, matting agents, surface conditioners, degassing agents, flow agents, heat stabilizers, antistatic agents, rust inhibitors, silane coupling agents, low-pollution treatment agents, plasticizers, adhesives, etc.

[0184] The coating may or may not contain a solvent (water, organic solvent, etc.), but preferably contains no solvent. The content of the solvent is preferably less than 1% by mass, more preferably less than 1% by mass, and further preferably 0% by mass, relative to the total mass of the coating.

[0185] The present coating material can be produced by mixing the specific fluorinated copolymer and, if necessary, additives, etc. The mixed specific fluorinated copolymer and additives, etc. are each in the form of independent powders or pellets.

[0186] One embodiment of the method for producing the present coating material is a method of melt-kneading the specific fluorinated copolymer and, if necessary, additives, etc., followed by cooling and pulverizing to obtain a powder coating material. The melt-kneading temperature is preferably 80 to 130°C.

[0187] In addition, as one aspect of the method for producing the present coating, there is a method of mixing a powder containing a specific fluorinated copolymer and a powder of an additive used as required to obtain a powder coating. This method is also called dry blending and is a method in which melt kneading is not performed during mixing.

[0188] The pulverization can be performed using a pulverizer such as a pin mill, a hammer mill, or a jet mill. Preferably, the pulverized material is classified after pulverization so that the particle size of the obtained powder coating is uniform. The average particle size of the powder coating is preferably 1 to 100 μm, more preferably 10 to 80 μm.

[0189] The coating film of the present invention (hereinafter also referred to as the present coating film) is formed by applying the present coating material to a substrate.

[0190] Furthermore, the coated article of the present invention comprises a substrate and a coating film formed of the present coating material and disposed on the substrate.

[0191] Specific examples of the material of the substrate include inorganic substances, organic substances, and organic-inorganic composite materials.

[0192] Specific examples of inorganic substances include concrete, natural stone, glass, and metals (iron, stainless steel, aluminum, copper, brass, titanium, etc.).

[0193] Specific examples of organic substances include plastics, rubber, adhesives, and wood.

[0194] Specific examples of the organic-inorganic composite material include fiber-reinforced plastics, resin-reinforced concrete, and fiber-reinforced concrete.

[0195] The substrate may be subjected to a known surface treatment (chemical conversion treatment, etc.) Alternatively, the substrate may have a resin layer (polyester resin layer, acrylic resin layer, silicone resin layer, etc.) formed by applying a primer, etc. on the surface of the substrate in advance.

[0196] The material of the substrate is preferably metal, more preferably iron, an alloy containing iron (eg, carbon steel, stainless steel), or aluminum.

[0197] Specific examples of the shape of the substrate include a flat plate shape, a spherical shape, and a rod shape.

[0198] The film thickness of the present coating film is preferably 20 to 1,000 μm, more preferably 20 to 500 μm.

[0199] The coated article of the present invention is preferably obtained by applying (coating) the present coating material to the surface of a substrate to form a coating layer, and then heating the obtained coating layer and then cooling it.

[0200] Examples of the method for forming the coating layer include electrostatic coating, electrostatic spraying, electrostatic dipping, fluidized dipping, and spraying. Electrostatic coating using a powder coating gun is preferred.

[0201] Specific examples of powder coating guns include corona charging type coating guns and friction charging type coating guns. A corona charging type coating gun is a coating gun that performs corona discharge treatment on powder coating and blows it. A friction charging type coating gun is a coating gun that performs friction charging treatment on powder coating and blows it.

[0202] The heating temperature during the heat treatment is preferably 120 to 250° C. The heating maintenance time is usually 2 to 60 minutes. After the heat treatment, it is preferably cooled to 20 to 25° C. The coating layer melts and solidifies (melt solidification) by the heat treatment and cooling to form the present coating film.

[0203] Example

[0204] Hereinafter, the present invention will be described in detail with reference to examples. Examples 1 to 7 are embodiments, and Examples 8 to 10 are comparative examples. However, the present invention is not limited to these examples. It should be noted that the blending amount of each component in the table described below is based on mass unless otherwise specified.

[0205] (Example 1)

[0206] Into a stainless steel pressure-resistant reactor having an internal volume of 2500 ml equipped with a stirrer, 20 g of a piperidyl group-containing compound (manufactured by BASF, trade name "TINUVIN292", a mixture of bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and methyl 1,2,2,6,6-pentamethyl-4-piperidyl sebacate (mass ratio 3:1)), 20 g of hydrotalcite (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%), 679 g of xylene, 118 g of 4-hydroxybutyl vinyl ether (hereinafter, also referred to as HBVE), and 453 g of cyclohexyl vinyl ether (hereinafter, also referred to as CHVE) were charged, and dissolved oxygen in the liquid was removed by degassing with nitrogen. Furthermore, 536 g of chlorotrifluoroethylene (hereinafter, also referred to as CTFE) was introduced into the reactor and the temperature was raised. When the temperature in the reactor reached 65° C., the pressure was 0.59 MPaG. Thereafter, 2 ml of a 5% xylene solution of tert-butyl peroxypivalate (hereinafter, also referred to as PBPV) was added to the reactor to start the reaction.

[0207] While maintaining the pressure as it decreases, a monomer mixture of 110 g of CTFE, 93 g of CHVE, and 24 g of HBVE is continuously added to the reactor to continue the reaction. Then, a 5% xylene solution of PBPV as a free radical polymerization initiator is intermittently added to the reactor in a total of 55 ml to carry out polymerization. After 16 hours, the reactor is water-cooled to stop the reaction.

[0208] After the reaction solution is cooled to room temperature, the unreacted monomers are purged, the insoluble components of the obtained reaction solution are removed by filtration, and then an appropriate amount of xylene is added to obtain a fluorinated copolymer solution (A-1) with a solid content concentration of 65%. The fluorinated copolymer solution (A-1) contains a fluorinated copolymer, a piperidinyl-containing compound and xylene.

[0209] Then, the volatile components were removed by vacuum drying at 65°C for 3 hours. Then, the volatile components were removed by vacuum heating at 130°C for 20 minutes to obtain a fluorinated copolymer composition (B-1). The heating residual component of the fluorinated copolymer composition (B-1) was measured and the result was confirmed to be 99.8% by mass. The fluorinated copolymer composition (B-1) contains a fluorinated copolymer and a piperidinyl-containing compound. The composition of the fluorinated copolymer in the fluorinated copolymer composition (B-1) is CTFE / CHVE / HBVE (mol%) = 50 / 39 / 11.

[0210] (Example 2)

[0211] In a stainless steel pressure-resistant reactor with an internal volume of 2500 ml equipped with a stirrer, 22 g of a piperidyl-containing compound (manufactured by BASF, trade name "TINUVIN292", a mixture of bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and methyl 1,2,2,6,6-pentamethyl-4-piperidyl sebacate (mass ratio 3:1)), 22 g of hydrotalcite (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%), 726 g of xylene, 79 g of HBVE, and 303 g of CHVE were placed, and dissolved oxygen in the liquid was removed by degassing with nitrogen. Furthermore, 357 g of CTFE was introduced into the reactor and the temperature was raised. The pressure was 0.55 MPaG when the temperature in the reactor reached 75° C. Thereafter, 6 ml of a 20% xylene solution of PBPV was added to the reactor to initiate the reaction.

[0212] While maintaining the pressure as it decreases, a monomer mixture of 350 g of CTFE, 297 g of CHVE, and 78 g of HBVE is continuously added to the reactor to continue the reaction. Then, a 20% xylene solution of PBPV as a free radical polymerization initiator is intermittently added to the reactor in a total of 25 ml to carry out polymerization. After 16 hours, the reactor is water-cooled to stop the reaction.

[0213] After the reaction solution is cooled to room temperature, the unreacted monomers are purged, the insoluble components of the obtained reaction solution are removed by filtration, and then an appropriate amount of xylene is added to obtain a fluorinated copolymer solution (A-2) with a solid content concentration of 65%. The fluorinated copolymer solution (A-2) contains a fluorinated copolymer, a piperidine-containing compound and xylene.

[0214] Then, the volatile components were removed by vacuum drying at 65°C for 3 hours. Then, the volatile components were removed by vacuum heating at 130°C for 20 minutes to obtain a fluorinated copolymer composition (B-2). The heating residual component of the fluorinated copolymer composition (B-2) was measured and found to be 99.7% by mass. The composition of the fluorinated copolymer in the fluorinated copolymer composition (B-2) was CTFE / CHVE / HBVE (mol%) = 50 / 39 / 11.

[0215] (Example 3~Example 7)

[0216] The amount of each component and the polymerization temperature were as shown in Table 1. Except for this, the same operation as in Example 2 was carried out to obtain fluorinated copolymer compositions (B-3) to (B-7). The fluorinated copolymer compositions (B-3) to (B-7) all contain a fluorinated copolymer and a piperidinyl-containing compound. The composition of the fluorinated copolymer in the fluorinated copolymer compositions (B-3) to (B-7) is CTFE / CHVE / HBVE (mol%) = 50 / 39 / 11.

[0217] (Example 8)

[0218] In a stainless steel pressure-resistant reactor with an internal volume of 2500 ml equipped with a stirrer, 11 g of potassium carbonate, 156 g of ethanol, 625 g of xylene, 75 g of HBVE, and 82 g of CHVE were added, and the dissolved oxygen in the liquid was removed by degassing with nitrogen. Furthermore, 151 g of CTFE was introduced into the reactor and the temperature was raised. When the temperature in the reactor reached 65° C., the pressure was 0.33 MPaG.

[0219] Thereafter, 6 ml of PBPV 50% xylene solution was added to the reactor to start the reaction. While maintaining the pressure as it decreased, a monomer mixture of 443 g of CTFE, 240 g of CHVE, and 221 g of HBVE was continuously added to continue the reaction. Then, 34 ml of PBPV 50% xylene solution as a free radical polymerization initiator was intermittently added to the reactor to proceed with polymerization. After 16 hours, the reactor was water-cooled to stop the reaction.

[0220] After the reaction solution was cooled to room temperature, the unreacted monomers were purged, the insoluble components of the obtained reaction solution were removed by filtration, and then an appropriate amount of xylene was added to obtain a fluorinated copolymer solution (A-8) with a solid content concentration of 65%. The fluorinated copolymer solution (A-8) contains a fluorinated copolymer, xylene and ethanol.

[0221] Then, the volatile components were removed by vacuum drying at 65°C for 3 hours. Then, the volatile components were removed by vacuum heating at 130°C for 20 minutes to obtain a fluorinated copolymer composition (B-8). The heating residual component of the fluorinated copolymer composition was measured and the result was confirmed to be 99.5% by mass. The fluorinated copolymer composition (B-8) contains a fluorinated copolymer. The composition of the fluorinated copolymer in the fluorinated copolymer composition (B-8) is CTFE / CHVE / HBVE (mol%) = 50 / 25 / 25.

[0222] (Examples 9~10)

[0223] The fluorinated copolymer compositions (B-9) to (B-10) were obtained in the same manner as in Example 1 except that the amounts of the components were as shown in Table 1. The fluorinated copolymer compositions (B-9) to (B-10) all contained a fluorinated copolymer and a piperidinyl-containing compound. The composition of the fluorinated copolymer in the fluorinated copolymer compositions (B-9) to (B-10) was CTFE / CHVE / HBVE (mol %) = 50 / 39 / 11.

[0224] (Measurement of Molecular Weight, etc. of Fluorinated Copolymer)

[0225] The fluorinated copolymer in each fluorinated copolymer composition was separated to obtain a solution diluted with tetrahydrofuran (THF) to a concentration of 1% by mass of the fluorinated copolymer. The obtained solution was filtered through a hydrophilic PTFE membrane filter with a pore size of 0.45 μm, and 1.5 ml of the filtered solution (measurement solution) was filled into a transparent glass vial with a capacity of 2 ml.

[0226] Next, by gel permeation chromatography, an elution curve (chromatogram) of the specific fluorinated copolymer was obtained from the elution time and the detection intensity based on RI (differential refractometer).

[0227] Then, using a polystyrene calibration curve, Mw, Mn, and Mw / Mn of the fluorinated copolymer were determined from the retention time of the obtained elution curve.

[0228] In addition, the obtained dissolution curve is baselined to determine the peak of the specific fluorinated copolymer. Next, the dissolution time is converted into molecular weight using a polystyrene standard curve to determine the peak area (regional area) of the dissolution curve. After calculating the concentration fraction at each dissolution time, the concentration fraction is accumulated, and the logarithmic value of the molecular weight is plotted on the horizontal axis and the cumulative value (%) of the concentration fraction is plotted on the vertical axis, thereby obtaining the integral molecular weight distribution curve of the specific fluorinated copolymer. Based on the obtained integral molecular weight distribution curve, the proportion of components with a molecular weight of less than 1100 (proportion M1) and the proportion of components with a molecular weight of less than 2000 (proportion M2) of the specific fluorinated copolymer are determined. The results are shown in Table 1.

[0229] <Measurement Conditions by Gel Permeation Chromatography>

[0230] Device: HLC-8320GPC (manufactured by Tosoh Corporation)

[0231] Analytical column: Two Shodex GPC KF-806M (manufactured by Showa Denko K.K.) and one Shodex GPC KF-802 (manufactured by Showa Denko K.K.) connected and used

[0232] Column oven: 40°C

[0233] Pump temperature box: 40℃

[0234] Eluent: Tetrahydrofuran

[0235] Flow rate: 1.0ml / min

[0236] Detector: RI

[0237] Standard curve sample: EasiCal PS-1 (polystyrene, manufactured by Agilent)

[0238] Standard curve molecular weight range: 580~570000

[0239] (Tg)

[0240] The Tg of the fluorinated copolymer was determined using a differential scanning calorimeter (DSC3500Sirius, manufactured by NETZSCH).

[0241] (Melt viscosity)

[0242] Using a rotational rheometer (HAAKE MARS40, manufactured by Thermo Fisher), the temperature was raised from 130°C to 200°C under the conditions of a frequency of 1 Hz and a heating rate of 10°C / min, and the melt viscosity of the fluorinated copolymer at 170°C was determined.

[0243] (Anti-blocking)

[0244] The fluorinated copolymer composition of each example was powdered using a pulverizer. 5 g of the powdered fluorinated copolymer composition was placed in a 20 ml glass container. The glass container was heated to 40° C. in a desiccator. After 60 days, the glass container was taken out of the desiccator and cooled to room temperature.

[0245] After cooling, the state of the powder of the fluorinated copolymer composition was evaluated according to the following criteria.

[0246] ○: The powder state was maintained.

[0247] △: Aggregated together, but returned to powder when vibrated.

[0248] ×: Agglomerated and not restored to powder even by vibration.

[0249] (Evaluation of Smoothness)

[0250] <Manufacturing of Powder Coatings>

[0251] The fluorinated copolymer composition of each example was powdered by a pulverizer.

[0252] Next, using the powdery fluorinated copolymer compositions of Examples 1 to 7 and 9 to 10, powdery mixtures were prepared in the following manner. To 100 parts by mass of the powdery fluorinated copolymer composition, 67 parts by mass of titanium oxide (Ti-Pure (registered trademark) R960 manufactured by DuPont), 25 parts by mass of a blocked isocyanate curing agent (VESTAGON (registered trademark) B1530 manufactured by Evonik), 0.012 parts by mass of a xylene solution of di-tert-butyltin dilaurate (10,000-fold diluted product) as a curing catalyst, 0.8 parts by mass of benzoin as a deaerator, and 2 parts by mass of a surface conditioner (BYK (registered trademark)-360P manufactured by BYK) were added, and the mixture was mixed for about 10 to 30 minutes using a high-speed homogenizer (manufactured by Yusaki Co., Ltd.) to obtain a powdery mixture.

[0253] Separately, a powdery mixture was prepared by the following procedure using the powdery fluorinated copolymer composition of Example 8. To 100 parts by mass of the powdery fluorinated copolymer composition, 69 parts by mass of titanium oxide (Ti-Pure (registered trademark) R960 manufactured by DuPont), 78 parts by mass of a blocked isocyanate curing agent (Crelan (registered trademark) UI manufactured by Sumika Covestro Urethane Co., Ltd.), 0.4 parts by mass of a xylene solution of di-tert-butyltin dilaurate (100-fold diluted product) as a curing catalyst, 1.3 parts by mass of benzoin as a deaerator, and 3 parts by mass of a surface conditioner (BYK (registered trademark)-360P manufactured by BYK) were added, and the mixture was mixed for about 10 to 30 minutes using a high-speed homogenizer (manufactured by Yusaki Co., Ltd.) to obtain a powdery mixture.

[0254] Next, the powdery mixture was melt-kneaded using a twin-screw extruder (manufactured by Thermo Prism, 16 mm extruder) at a barrel setting temperature of 120° C. to obtain pellets. The obtained pellets were pulverized at room temperature using a pulverizer (manufactured by FRITSCH, RotorSpeed ​​Mill P14) and classified using a 150-mesh sieve to obtain a powder coating having an average particle size of about 40 μm.

[0255] <Manufacturing of substrate with coating film>

[0256] The obtained powder coating material was used to electrostatically coat one surface of the aluminum plate subjected to chromate treatment using an electrostatic coating machine (GX3600C manufactured by Onoda Cement Co., Ltd.) to form a coating layer of the powder coating material.

[0257] Next, the aluminum plate with a coating layer corresponding to Example 1 was kept in an atmosphere of 200° C. for 20 minutes. Also, the aluminum plate with a coating layer corresponding to the other examples was kept in an atmosphere of 170° C. for 20 minutes.

[0258] After heating, the aluminum plate with a coating layer corresponding to each example was left to cool to room temperature to obtain an aluminum plate with a coating film (cured film) having a film thickness of 55 to 65 μm.

[0259] <Evaluation method of smoothness>

[0260] The surface smoothness of the coating film of the aluminum plate with coating film was evaluated according to the following criteria using a PCI (Powder Coating Institute) smoothness visual judgment marking plate. It should be noted that the marking plate has 10 sheets from 1 to 10, and as the number increases, the smoothness is excellent. The results are shown in Table 1.

[0261] ○: PCI value is 4 or more.

[0262] △: PCI value is 2 or more and less than 4.

[0263] ×: PCI value is less than 2.

[0264] In the following Table 1, Mm / Ma represents the ratio of the total molar amount Mm of chlorotrifluoroethylene and vinyl ether in the reactor before the start of polymerization to the total amount Ma (molar amount) of chlorotrifluoroethylene and vinyl ether used in the production of the fluorinated copolymer.

[0265] In addition, Mm / Ms represents the ratio of the total molar amount Mm of the molar amount of chlorotrifluoroethylene and the molar amount of vinyl ether to the molar amount Ms of the solvent in the reactor before the start of polymerization.

[0266] A / B represents the ratio of the molar ratio A of the vinyl ether to chlorotrifluoroethylene in the reactor before the start of polymerization to the molar ratio B of the vinyl ether to chlorotrifluoroethylene in the monomer mixture.

[0267] Further, M1 represents the ratio of the component having a molecular weight of 1,100 or less in the fluorinated copolymer, and M2 represents the ratio of the component having a molecular weight of 2,000 or less in the fluorinated copolymer.

[0268] [Table 1]

[0269]

[0270] As shown in Table 1, it was confirmed that a powder coating material having excellent anti-blocking properties can be obtained when the fluorinated copolymer comprises units derived from CTFE and units derived from vinyl ether and the ratio M1 is 0.6% or less and the Mw / Mn is 2.0 to 3.2.

[0271] It should be noted that the entire contents of the specification, claims, and abstract of Japanese Patent Application No. 2022-108420 filed on Jul. 5, 2022 are cited herein and incorporated as a disclosure of the specification of the present invention.

Claims

1. A fluorinated copolymer, characterized in that containing units based on chlorotrifluoroethylene and units based on vinyl ether, The proportion of components with a molecular weight of 1100 or less determined from the integrated molecular weight distribution curve is 0.6% or less. The molecular weight distribution of the fluorine-containing copolymer is 2.0-3.

2. 2 . The fluorinated copolymer according to claim 1 , wherein the proportion of components having a molecular weight of 2,000 or less determined from the integrated molecular weight distribution curve is at most 2.80%.

3. The fluorinated copolymer according to claim 1, which has a weight average molecular weight of 10,000 to 60,000. The fluorinated copolymer according to claim 1 , which has a crosslinkable group.

5. The fluorinated copolymer according to claim 4, wherein The crosslinking group is a hydroxyl group or a carboxyl group.

6. The fluorinated copolymer according to claim 1, wherein The content of the units based on chlorotrifluoroethylene is 30 to 70 mol % based on all repeating units of the fluorinated copolymer.

7. The fluorinated copolymer according to claim 1, wherein The vinyl ether-based unit includes a unit having a crosslinkable group, The content of the unit having a crosslinkable group is 1 to 20 mol % based on all repeating units of the fluorinated copolymer.

8. The fluorinated copolymer according to claim 1, wherein The vinyl ether-based units include units having no crosslinking group, The content of the unit having no crosslinkable group is 1 to 70 mol % based on all repeating units of the fluorinated copolymer.

9. A composition, characterized in that The method comprises the fluorinated copolymer according to any one of claims 1 to 8 and a piperidinyl group-containing compound.

10. A composition, characterized in that The method comprises the fluorinated copolymer according to any one of claims 1 to 8 and a solvent.

11. A powder coating, characterized in that: A fluorinated copolymer according to any one of claims 1 to 8.

12. A method for producing a coated article, characterized in that: The powder coating material according to claim 11 is applied to the surface of a substrate to form a coating layer, and the coating layer is melted and solidified to form a coating film.

13. A method for producing a fluorinated copolymer, characterized in that: The fluorine-containing copolymer comprises a unit based on chlorotrifluoroethylene and a unit based on vinyl ether, The production method comprises the following steps: performing polymerization in a reactor in the presence of the chlorotrifluoroethylene, the vinyl ether, a solvent and a radical polymerization initiator to produce a fluorinated copolymer; After the polymerization is started, the mixture of chlorotrifluoroethylene and the vinyl ether is continuously or intermittently supplied to the reactor, In the reactor before starting the polymerization, the ratio of the total molar amount of the chlorotrifluoroethylene and the molar amount of the vinyl ether to the molar amount of the solvent is 0.30 or more, The molar ratio A of the vinyl ether to the chlorotrifluoroethylene in the reactor before starting the polymerization and the molar ratio B of the vinyl ether to the chlorotrifluoroethylene in the mixture satisfy the following relationship: 0.5≤A / B≤1.

5.

14. The method for producing a fluorinated copolymer according to claim 13, wherein The molar ratio of the total molar amount of the chlorotrifluoroethylene and the vinyl ether in the reactor before starting the polymerization to the total amount of the chlorotrifluoroethylene and the vinyl ether used in the production of the fluorinated copolymer is 0.3 or more.

15. The method for producing a fluorinated copolymer according to claim 13 or 14, wherein The polymerization is carried out in the presence of a piperidinyl-containing compound.

Images