JP2000154219A - Powder coating material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a coating material which can give a coating film being excellent in storage stability, etc., and having weather resistance and high adhesion by using a copolymer comprising tetrafluoroethylene units, ethylene units, and a specified total amount of propylene units and/or isobutylene units and having a specified melting point and a specified glass transition temperature. SOLUTION: This coating material comprises a fluoro copolymer comprising 35-65 mol% tetrafluoroethylene units, 5-60 mol% ethylene units, and 5-60 mol% propylene units and/or isobutylene units and having a melting point of 90-150 deg.C and a glass transition temperature of 20-80 deg.C. Alternatively, it comprises 100 pts.wt. above fluoro copolymer and 5-100 pts.wt. alkyl methacrylate polymer having a glass transition temperature of 60-110 deg.C. The fluoro copolymer is a low-melting cepalymer comprising, for example, vinylidene fluoride, tetrafluoroethylene, and hexafluoropropylene and having a Q value of 0.1-5,000 (the volume of the sample discharged from a cylinder of an inside diameter of 11.3 mm through a nozzle of an inside diameter of 2.1 mm and a length of 8 mm at 120 deg.C under a load of 7 kg).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a powder of a fluorine-based copolymer which can be pulverized at or near room temperature, and to a powder containing the fluorine-based copolymer, which has chemical resistance, stain removal property, weather resistance and adhesion. The present invention relates to a powder coating which gives an excellent coating film and has excellent storage stability.

[0002]

2. Description of the Related Art Dispersion type fluororesin paints containing polyvinylidene fluoride as a main component (Japanese Patent Publication No. 60-216)
67), a solvent-soluble thermosetting fluororesin paint containing a copolymer of fluoroolefin and vinyl ether (JP-A-59-102962) or a solvent-soluble heat containing a copolymer of fluoroolefin and vinyl ester Curable fluororesin coatings (JP-A-61-57609) provide coatings with excellent corrosion resistance, durability, and ease of removal of dirt, and have recently been widely used in coatings for heavy-duty corrosion protection, construction, industrial use, and the like. It is used.

On the other hand, fluororesin powder coatings that do not discharge organic solvents have been proposed in order to cope with the problem of environmental pollution that has become more serious each year (Japanese Patent Laid-Open Nos. 1-103670 and 2-102).
60968, JP-A-6-345822, JP-A-7-14
5332). Usually, a powder coating is produced by melt-kneading a composition containing a resin component and other additives that have been pulverized in advance, and then pulverizing the composition.

A powder coating containing polyvinylidene fluoride as a main component has a melting point of polyvinylidene fluoride of 200%.
It is necessary to bake at a high temperature of ℃ or more,
Since polyvinylidene fluoride is crystalline, it is difficult to obtain a sufficiently glossy coating film from the coating material, and there is a problem that its use is limited.

[0005] Vinylidene fluoride (hereinafter referred to as VdF)
And a powder coating mainly composed of a low-melting polymer obtained by copolymerizing tetrafluoroethylene (hereinafter referred to as TFE) or hexafluoropropylene (Japanese Patent Application Laid-Open No. 3-220272). However, in this case, it is necessary to pulverize the low melting point polymer in advance at a low temperature, and there is a problem that the cost of the coating material is increased.

As a polymer which can be ground at room temperature, a fluorine-based copolymer of an allyl compound having a carboxyl group, VdF and TFE has been proposed (Japanese Patent No. 272000).
No. 5). However, the powder coating containing this copolymer has problems such as storage stability in which unreacted allyl compound remaining in the copolymer at the time of polymerization acts as a plasticizer to cause blocking and the like. There is a problem that the use of an expensive allyl compound increases the cost.

[0007] Since a copolymer of a fluoroolefin and a vinyl ether or a vinyl ester has a cured portion and is thermosetting, a paint containing the copolymer can be powder-coated at a relatively low temperature, and gloss and transparency can be improved. A coating film having excellent solvent resistance and mechanical strength can be obtained. However, in order to prevent the powder coating material containing the copolymer from being clumped during storage, a vinyl ether or vinyl ester having a cyclohexyl group or an alkyl group having a large number of carbon atoms is used to obtain a glass transition temperature (hereinafter, T _g). Is producing high copolymers. However, since the above-mentioned vinyl ether or vinyl ester is a monomer having a high boiling point, it is difficult to dry and remove the monomer which remains unreacted during polymerization from the copolymer, and also has a high boiling point. There was a problem that the copolymer in which the monomer remained remained easily colored or gelled.

[0008]

SUMMARY OF THE INVENTION The present invention comprises a fluorine-based copolymer which can be ground at or near room temperature, has excellent storage stability and drying properties, and has chemical resistance, weather resistance and adhesion. To provide a powder coating which gives an excellent coating film.

[0009]

According to the present invention, there are provided (a) 35 to 65 mol% of polymerized units based on tetrafluoroethylene, (b) 5 to 60 mol% of polymerized units based on ethylene, and (c) propylene. Polymerized units based on
Or (d) a total of 5 to 5 polymerized units based on isobutylene;
Provided is a powder comprising a fluorine-based copolymer having a melting point of 90 to 150 ° C and a glass transition temperature of 20 to 80 ° C, which is contained at a ratio of 60 mol%. Further, the present invention provides a powder coating containing the fluorine-based copolymer. Also provides a powder coating material containing this and fluorine-based copolymer 100 parts by weight, and the T _g methacrylic acid alkyl ester-based polymer 5-100 parts by weight of 60 to 110 ° C..

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The fluorine-based copolymer in the present invention is preferably composed of polymerized units based on the following monomers. (A) 35-65 mol% of TFE, (b) 5-55 mol% of ethylene, (c) propylene (10)-(60) mol%, (d) isobutylene (10)-(60) mol%.

Particularly preferred is as follows. (A) 40 to 60 mol% of TFE, (b) 15 to 40 mol% of ethylene, (c) propylene (20) to (40) mol%, (d) isobutylene (20) to (40) mol%.

Here, polymerized units (c) propylene and (d)
The composition ratio of isobutylene in parentheses is (1
The notations 0), (60) and the like have the following meanings. That is, in the present invention, at least one of (c) and (d) is always contained, and the other may not be contained at all, but (10), (60), etc. are contained in that case ( The content of the component (c) or (d) alone is shown. When both (c) and (d) are contained,
(10), (60) and the like indicate the total content of both components.

In the case where the fluorine-based copolymer of the present invention is used in a coating, if the proportion of the polymerized unit (a) is too small, the coating is inferior in weather resistance, and if it is too large, the cost becomes higher as compared with the improvement in weather resistance. Not preferred. Thus, the above range is selected. If the proportion of the polymerized unit (b) is too small, the fluorocopolymer becomes rubbery and it becomes difficult to pulverize at room temperature or near room temperature, and the hardness of the coating film becomes insufficient, and if it is too large, the melting point becomes high. The flexibility of the coating film is insufficient. Thus, the above range is selected.

As described above, the polymerized units (c) and (d) may be used simultaneously, or only one of them may be used, but at least one of them is used. If the proportion of (c) and / or (d) is too small, the melting point of the fluorine-based copolymer will be too high, and the crystallization of the coating film will be large and the transparency will be reduced. Conversely, if the amount is too large, the fluorocopolymer becomes rubbery and it becomes difficult to pulverize the fluorocopolymer at or near room temperature. The above range is selected in consideration of these.

The powder comprising the fluorocopolymer of the present invention can be obtained by pulverizing the fluorocopolymer at or near room temperature. This powder is useful as a resin component or the like for forming a coating film, and is blended in, for example, a powder coating. The particle size of the powder composed of the fluorine-based copolymer is usually 1 to 500 µm, preferably 5 to 300 µm, more preferably 10 to 100 µm.

The fluorine-based copolymer has a melting point of 90 to 150.
Those in the range of ° C are used. If the melting point is too low, pulverization of the fluorine-based copolymer becomes difficult, and if the melting point is too high, the powder of the fluorine-based copolymer does not sufficiently flow during heating coating,
It is not preferable because the appearance of the obtained coating film is impaired.

The fluorine-based copolymer has a T _g of 20 to 80 ° C.
Those in the range are used. T _g grinding of fluorocopolymer at around room temperature is too low, it becomes difficult, T _g is a powder of the fluorocopolymer is not sufficiently flow at too high a heating paint, the resulting coating film Is unfavorable because the appearance is deteriorated.

The Q value, which is a scale representing the molecular weight of the fluorocopolymer, is preferably from 0.1 to 5,000 at 120 ° C., more preferably from 1 to 1,000. If the Q value is too small, not only the pulverization of the fluorocopolymer becomes difficult, but also the fluidity of the powder of the fluorocopolymer at the time of coating deteriorates, and if it is too large, the mechanical strength of the coating film becomes low. Therefore, it is not preferable.

Here, the Q value refers to a nozzle having an inner diameter of 2.1 mm and a length of 8 mm filled with a fluorocopolymer in a cylinder having an inner diameter of 11.3 mm at a load of 7 kg at 120 ° C. using a Koka type flow tester. It is a value defined by the volume (mm ³ / sec) extruded in a unit time at the time of extrusion.

All of the monomers constituting the polymerized units contained in the fluorocopolymer are gaseous at normal temperature and normal pressure, and after the polymerization is completed, residual monomers are easily purged from the fluorocopolymer. Have the following characteristics. Therefore, the fluorine-based copolymer in the present invention can be easily dried. The fluorine-based copolymer can also be produced by a polymerization method such as emulsion polymerization, solution polymerization, suspension polymerization and the like which are usually employed.

The powder coating of the present invention contains a fluorine-based copolymer which is a resin component for forming a coating film. Further, in the powder coating containing the fluorine-based copolymer of the present invention, a polymer other than the fluorine-based copolymer as a resin component for forming a coating film, for example, a polyester-based polymer, an acrylic-based polymer And the like. The ratio of the other polymer to the fluorine-based copolymer is preferably 5 to 100 parts by weight, more preferably 10 to 4 parts by weight, based on 100 parts by weight of the fluorine-based copolymer.
5 parts by weight is more preferred. As an acrylic polymer,
Alkyl methacrylate polymers are preferred.

As the methacrylic acid alkyl ester-based polymer, those having a T _{g in} the range of 60 to 110 ° C. are more preferable. When the glass transition temperature is less than 60 ° C., the powder coating composition tends to cause blocking, the surface hardness of the obtained coating film is low, the softening is easy, and contaminants are easily attached to the coating film. If the temperature exceeds 110 ° C., the flexibility of the coating film is lost, the bending performance is reduced, and the coating film is easily cracked. Particularly, the range of 70 to 90 ° C. is preferable.

The molecular weight of the alkyl methacrylate polymer is determined by gel permeation chromatography (GPC).
Number average molecular weight ( _Mn ) of 5 × 10 ³ to 1 × 10 ⁵
Are preferred. If _Mn is smaller than this, the coating film tends to be brittle, and if it is larger than this, the fluidity during baking is reduced and the smoothness of the coating film is likely to be impaired.

The methacrylic acid alkyl ester-based polymer may be a homopolymer of an alkyl methacrylate or a copolymer of an alkyl methacrylate and a monomer copolymerizable therewith. As the methacrylic acid alkyl ester, the alkyl group has 1 to 12 carbon atoms.
And a methacrylic acid alkyl ester. In order to increase the T _g of the methacrylic acid alkyl ester polymer, it has a linear alkyl group having 1 to 4 carbon atoms or a sterically bulky alkyl group having 3 or more carbon atoms such as a branched or cyclic structure. Alkyl methacrylate is preferred.

Specific examples of the alkyl methacrylate include methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate and the like. Can be

Examples of the monomer copolymerizable with the alkyl methacrylate include vinyl cyanide compounds such as acrylonitrile, aromatic vinyl compounds such as styrene, unsaturated carboxylic acids such as maleic acid, and vinyl esters such as vinyl acetate. And the like. The proportion of the polymerized units based on these monomers in the alkyl methacrylate polymer is preferably 20% by weight or less. 20% by weight
If the amount is larger than the above range, the weather resistance of the alkyl methacrylate-based polymer decreases, which is not preferable. The alkyl methacrylate-based polymer can be produced by a polymerization method such as emulsion polymerization, solution polymerization, suspension polymerization and the like which are usually employed.

[0027] The fluorine-containing copolymer and T _g is 60~110 ℃
And the methacrylic acid alkyl ester-based polymer having a T _g of 60 to 110 ° C. with respect to 100 parts by weight of the fluorine-based copolymer. It is blended at a ratio of １００100 parts by weight. Particularly, 10 to 45 parts by weight is preferable. If the amount of the alkyl methacrylate polymer is less than this, the adhesion of the coating film is not sufficient, and if it is more than this, the flexibility of the coating film is impaired.

The powder coating composition of the present invention may further comprise a surface smoothing agent, a silane coupling agent, an ultraviolet absorber, a light stabilizer, a coloring pigment, if necessary, in addition to the fluorine-based copolymer and the alkyl methacrylate-based polymer. , A metallic pigment, an extender pigment and the like. After mixing these components in a powder state, the extruder melt-mixes the fluorine-based copolymer and the alkyl methacrylate-based polymer. Usually, 100 to 160 ° C. is adopted as the melting temperature. The melted and extruded composition is cooled and ground at room temperature. The particle size of the pulverized composition is 20 to 50 μm for spray coating,
It is preferably 70 to 120 µm for fluid immersion coating.

For the purpose of preventing blocking of the powder composition particles and improving the flowability, the surface of the powder composition particles is coated with an organic compound having an average particle diameter of 0.1 to 10 μm, particularly preferably 0.1 to 5 μm. Alternatively, it is preferable to coat with fine particles of an inorganic compound. Barium sulfate,
Examples include calcium carbonate, aluminum oxide, calcium silicate, magnesium silicate, antimony oxide, titanium dioxide, iron oxide, and finely divided silica. Examples of the organic compound include a polyolefin such as an isobutylene polymer and an acrylic copolymer.

[0030]

EXAMPLES Examples (Examples 1 to 7) and Comparative Examples (Examples 8 to 7)
This will be described in detail with reference to 10), but the present invention is not limited to these. Polymers 1 to 6 are examples relating to powders composed of the fluorine-based copolymer of the present invention, polymers 7 to 9 are comparative examples relating to powders composed of fluorine-based copolymers other than the present invention, and polymer 10 is a powder of the present invention. It is a synthesis example of the alkyl methacrylate polymer in the invention.

[Polymer 1] An autoclave with a stirrer made of stainless steel and having a capacity of 2.5 L was repeatedly evacuated under vacuum and repeatedly pressurized with nitrogen gas to remove air, and then CCClF ₂ CF ₂ CH.
1170 of ClF (hereinafter referred to as HCFC225cb)
g, TFE 192 g, ethylene 6 g, propylene 10.
1 g was charged into an autoclave. When the temperature in the autoclave reaches 50 ° C., the pressure is 14.7 kg / cm ^2.
G is indicated. Thereafter, 2 cc of a 5% by weight HCFC225cb solution of an initiator Parloyl IPP (manufactured by NOF Corporation) was added to initiate a solution polymerization reaction. TFE / propylene / ethylene was 55/30 /
The reaction was continued while continuously adding 56 g of a 15 mol% mixed gas and maintaining the pressure. During the progress of the reaction, 5% by weight of parroyl IPP in HCFC225cb solution 15c
c was added continuously.

After 3.5 hours, the supply of the mixed gas was stopped, the autoclave was cooled with water, and unreacted monomers were purged. The obtained fluorine-based copolymer at 4 mmHg for 5 hours,
After removing the solvent, the mixture was pulverized with an impact hammer mill to obtain a powder of a fluorocopolymer. As a result of ¹³ C-NMR analysis, the composition of the fluorine-based copolymer was 56 mol% of polymerized units based on TFE, 16 mol% of polymerized units based on ethylene, and 28 mol% based on propylene.
The melting point was 92.7 ° C., the T _g was 23.7 ° C., and the Q value was 5.0. The pulverizability of the polymer according to the method shown in Table 3 was good. In Table 1, the numbers on the left side of the composition of the monomers indicate the molar ratio of the initial charge, and the numbers on the right side indicate the polymer units (mol%) based on each monomer in the polymer.

[Polymer 2] A 2.5-liter autoclave with a stirrer made of stainless steel and having a stirrer made of stainless steel was repeatedly evacuated and pressurized with nitrogen gas to remove air. 8 g and 5.1 g of isobutylene were charged into an autoclave. When the temperature in the autoclave reached 50 ° C., the pressure showed 13.8 kg / cm ² G. Thereafter, a 5 wt% HCFC225cb solution 2c of parloyl IPP was used.
c was added to initiate the solution polymerization reaction. In response to the pressure drop caused by the reaction, a mixed gas of 50/30/10/10 mol% of TFE / ethylene / propylene / isobutylene was used.
The reaction was continued while maintaining the pressure by continuously adding g. During the reaction, 5% by weight of parloyl IPP H
15 cc of CFC225cb solution was added continuously.

After 3.5 hours, the supply of the mixed gas was stopped, the autoclave was cooled with water, and the unreacted monomer was purged. The obtained fluorine-based copolymer at 4 mmHg for 5 hours,
After removing the solvent, the mixture was pulverized with an impact hammer mill to obtain a powder of a fluorocopolymer. The composition of the fluorine-based copolymer,
Table 1 shows the melting point, T _g , Q value and grindability.

[Polymer 3] Ion-exchanged water 1100 was placed in an autoclave with a stainless steel stirrer having an internal volume of 2.5 L.
g, emulsifier FC-143 (trade name: manufactured by Sumitomo 3M) 4.
75 g and 46.6 g of HCFC225cb were charged, and air was removed by repeating vacuum degassing and nitrogen gas pressurization.
72 g of FE, 1.4 g of ethylene and 1.1 g of propylene were charged in an autoclave. When the temperature in the autoclave reached 70 ° C., the pressure showed 13.4 kg / cm ² G. Thereafter, 2 cc of a 25% by weight aqueous solution of ammonium persulfate was added to start an emulsion polymerization reaction. TFE / ethylene / propylene is 5
130.5 g of a mixed gas of 0/25/25 mol% was continuously added, and the reaction was continued while maintaining the pressure. In addition,
During the progress of the reaction, a 30% by weight aqueous solution of ammonium persulfate 30
cc was added continuously.

After 6 hours, the supply of the mixed gas was stopped, the autoclave was cooled with water, and the unreacted monomers were purged.
A 20% aqueous solution of ammonium chloride was added to the obtained dispersion to aggregate the fine particles of the fluorocopolymer, which was filtered through a glass filter to remove water at 4 mmHg for 5 hours, and pulverized with an impact hammer mill. A copolymer powder was obtained. Table 1 shows the composition, melting point, T _g , Q value, and grindability of the fluorine-based copolymer.

[Polymers 4 to 6] The compositions, melting points, T _g , Q values and grindability of Polymers 4 to 6 synthesized by solution polymerization or emulsion polymerization in the same manner as Polymers 1 to 3 are shown in Table 1. .

[Polymer 7] As the polymer 7, a homopolymer of VdF (Kynar 500, manufactured by ELF Atochem) was used. Polymer 7 had a melting point of about 170 ° C., a T _g of −40 ° C., and a Q value of less than 0.1 at 120 ° C., and was not measurable. Further, the pulverizability of the polymer was poor, and -2.
Powder crushed at 0 ° C. was used as a composition raw material.

[Polymer 8] As polymer 8, TFE / V
dF / hexafluoropropylene-based copolymer (Kyna
r ADS, manufactured by ELF Atochem).
Polymer 8, melting point about 90 ° C., 28, T _g in Q value 120 ° C. was observed at -50 to 200 ° C.. Further, the pulverizability of the polymer was poor, and a powder pulverized at -20 ° C was used as a raw material for the composition.

[Polymer 9] As the polymer 9, TFE / V
dF copolymer (Kynar SL, ELF Atoc)
hem). Polymer 9 has a melting point of 125 ° C.
Q value is 3.9 at 150 ° C., T _g is −50 to 200
Not observed at ° C. Further, the pulverizability of the polymer was poor, and a powder pulverized at -20 ° C was used as a raw material for the composition.

[Polymer 10] Xylene 2 was placed in a 1 L glass flask equipped with a thermometer, stirrer, and reflux condenser.
The reaction vessel was replaced with nitrogen by charging 00 parts and heated to 100 ° C. Subsequently, a mixture of 190 parts of methyl methacrylate, 10 parts of t-butyl methacrylate, and 5 parts of azobisisobutyronitrile was continuously added for 4 hours, and then 0.5 part of azobisisobutyronitrile was added, and further 1 hour. The reaction was completed by heating. Thereafter, xylene was removed by evaporation to obtain a polymer 10 of an alkyl methacrylate polymer. The number average molecular weight (M _n ) of the polymer 10 is 4 ×
10 ⁴ , T _g was 93 ° C.

Example 1 37 parts of polymer 1 powder, polymer 1
No. 10 powder, Modaflow 2000 (Acrylic polymer leveling agent, manufactured by Monsanto Co., Ltd., hereinafter M2000
0.5 part, Tinuvin 900 (benzotriazole-based ultraviolet absorber, manufactured by Ciba-Geigy, hereinafter, T900
2 parts, Tinuvin 144 (hindered amine light stabilizer, manufactured by Ciba Geigy, hereinafter abbreviated as T144)
0.7 part was mixed with a Henschel mixer for about 1 minute, and then melt-mixed at a temperature of 90 to 130 ° C. using an extruder (Pscone Kneader PR-46, manufactured by PUS). Next, after cooling to 20 ° C., it was pulverized with an impact hammer mill,
A sieve powder coating was obtained with a 0 mesh wire mesh. Parts are weights.

Next, a zinc phosphate treated 1.8 m thick
The above powder paint is electrostatically spray-coated on an iron plate of
It heated at 20 degreeC for 20 minutes, and obtained the coating film with a film thickness of 50 micrometers. The coating film was subjected to the coating film performance test shown in Table 3. Table 4 shows the results.

[Examples 2 to 6] From the powders of the polymers 2 to 6, Table 2 was used.
Was prepared in the same manner as in Example 1 and electrostatically coated in the same manner as in Example 1 to perform a coating film performance test. Table 4 ~
It is shown in FIG.

Example 7 A powder coating was produced in the same manner as in Example 1 except that the polymer 10 was not used in Example 1, and the coating was subjected to electrostatic coating in the same manner as in Example 1 to perform a coating film performance test. Table 5 shows the results.

Examples 8 to 10 Polymers 7 to 9 cannot be ground at room temperature, but were cooled with liquid nitrogen and ground.
Was applied electrostatically in the same manner as in Example 1 to perform a coating film performance test. Table 5 shows the results.

[0047]

[Table 1]

[0048]

[Table 2]

[0049]

[Table 3]

[0050]

[Table 4]

[0051]

[Table 5]

[0052]

As described above, the fluorocopolymer of the present invention can be easily pulverized at or near room temperature to obtain a powder of the fluorocopolymer. The powder coating composition containing this fluorine-based copolymer has excellent storage stability, and also has solvent resistance, weather resistance,
Provides a coating film with excellent adhesion and the like.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09D 127/18 C09D 127/18 133/10 133/10 F term (Reference) 4J038 CB091 CB131 CD121 MA02 MA13 MA14 NA03 NA04 NA05 NA12 4J100 AA02Q AA03R AA06R AA06S AC26P CA05 CA06 DA01 DA09 DA24 DA25 EA00 JA01

Claims (6)

[Claims] (1) 35-65 mol% of polymerized units based on tetrafluoroethylene, (b) 5-60 mol% of polymerized units based on ethylene, and (c) polymerized units based on propylene and / or ( d) A powder comprising a fluorine-based copolymer containing a polymerized unit based on isobutylene at a ratio of 5 to 60 mol% in total, and having a melting point of 90 to 150 ° C and a glass transition temperature of 20 to 80 ° C. 2. Q as an index of the molecular weight of the fluorine-based copolymer
The powder according to claim 1, wherein the value is in the range of 0.1 to 1000. However, the Q value was measured by filling a fluorine-based copolymer into a cylinder having an inner diameter of 11.3 mm using a Koka type flow tester.
It is a value defined by the volume (mm ³ / sec) that is extruded from a nozzle having an inner diameter of 2.1 mm and a length of 8 mm at 20 ° C. under a load of 7 kg and is extruded in a unit time. 3. A polymerization unit based on (a) 35 to 65 mol% of a polymerization unit based on tetrafluoroethylene, (b) a polymerization unit based on 5 to 60 mol%, and (c) a polymerization unit based on propylene and / or ( d) Powder coating containing a fluorine-based copolymer having a total of 5 to 60 mol% of polymerized units based on isobutylene and having a melting point of 90 to 150 ° C and a glass transition temperature of 20 to 80 ° C. (4) 35-65 mol% of polymerized units based on tetrafluoroethylene, (b) 5-60 mol% of polymerized units based on ethylene, and (c) polymerized units based on propylene and / or ( d) 100 parts by weight of a fluorinated copolymer containing polymerized units based on isobutylene at a ratio of 5 to 60 mol% in total, having a melting point of 90 to 150 ° C. and a glass transition temperature of 20 to 80 ° C .; 6
A powder coating containing 5 to 100 parts by weight of an alkyl methacrylate-based polymer having a temperature of 0 to 110 ° C. 5. Q which is an index of the molecular weight of the fluorocopolymer
The powder coating according to claim 3, wherein the value is in the range of 0.1 to 1,000. However, the Q value was measured using a Koka type flow tester, and the fluorocopolymer was filled into a cylinder having an inner diameter of 11.3 mm, and the inner diameter was 2.1 mm under a 7 kg load at 120 ° C.
It is a value defined by the volume (mm ³ / sec) extruded from a nozzle having a length of 8 mm and extruded in a unit time at that time. 6. The methacrylic acid alkyl ester polymer has a number average molecular weight of 5 × 10 ³ to 1 × 10 ^{5 as} determined by gel permeation chromatography (GPC).
A powder coating according to claim 1.