JP2003012717A - Method for producing particles of fluorine-containing copolymer and composition for powder coating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing particles of a fluorine-containing copolymer capable of preventing formation of blocks and pasty materials, easy to handle, low in remaining organic solvent, in obtaining the particles of the copolymer by removing an organic solvent from an aqueous dispersion of the fluorine-containing copolymer dispersed in water and the organic solvent, and to obtain a composition for power coating using the same. SOLUTION: In this method for effectively obtaining resin particles useful for powder coating, from the dispersion comprising the fluorine-containing copolymer substantially soluble in THF comprising a fluoroolefin monomer and a hydrocarbon based monomer, water and the organic solvent by removing the organic solvent, formation of the blocks and the party materials is prevented by using a dispersion stabilizer.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing fluorine-containing copolymer particles. More specifically, the present invention relates to a method for producing fluorine-containing copolymer particles, in which fluorine-containing copolymer particles useful as a resin for powder coatings are efficiently recovered from an aqueous suspension using a polymerization reaction product liquid after polymerization. According to the production method of the present invention, the copolymer after polymerization can be easily recovered, post-treatment can be facilitated, and fluorine-containing copolymer particles having less residual solvent can be produced.

[0002]

BACKGROUND OF THE INVENTION Fluororesin is used in a wide range of applications such as coating agents, coating agents and water / oil repellents because it has excellent chemical resistance, weather resistance, heat resistance and water / oil repellency. ing.

In recent years, powder coatings have been widely used in metal coatings in general because they have the advantages of not containing a solvent and being recoverable and reusable. Among them, the demand for fluorine-based powder coatings is increasing for important applications of weather resistance such as building materials and bridges.

Solution polymerization, emulsion polymerization, suspension polymerization, organic solvent precipitation polymerization and the like are known as methods for producing the fluorine-containing copolymer for the fluorine-based powder coating material.
Japanese Patent Publication No. 6-104792 is known as an example of producing a fluorine-containing powder resin by a solution polymerization method, but in order to obtain a granular or powdery polymer having a small residual solvent,
Steps such as drying and crushing under high temperature or high vacuum are required.

Japanese Patent Application Laid-Open No. 2000-26767 is known as an example of the production of fluorine-containing copolymer particles by suspension polymerization. Generally, when producing fluorine-containing copolymer particles by suspension polymerization, after carrying out suspension polymerization of a fluorine-containing monomer in an aqueous polymerization medium containing a fluorine-containing organic liquid having a small chain transfer reactivity, the polymerization medium is distilled off. Although a method for obtaining the fluorinated copolymer particles by removal is carried out, it is difficult to distill off the polymerization medium in the fluorinated copolymer particles which are easily dissolved or swelled in the fluorinated organic liquid. Not only that, the copolymer particles are agglomerated by distilling off, or they become one piece like a dough (bread dough) as a whole and adhere to the stirring blade of the reaction tank, or in some cases, stir. It can be difficult or even difficult to remove and recover the polymer.

As a method for solving this problem, Japanese Patent No.
As reported in Japanese Patent No. 588619 and the like, a method of adding a dispersion stabilizer at the time of polymerization is known, but when the dispersion stabilizer is added to this polymerization system, the dispersion stabilizer causes a chain transfer reaction. To lower the polymerization rate,
Since it causes a graft reaction, there is a problem that the physical properties of the coating film obtained when used as a powder coating are deteriorated.

[0007]

DISCLOSURE OF THE INVENTION An object of the present invention is to prevent agglomeration and dough formation of particles when recovering copolymer particles from a polymerization reaction product solution of a fluorinated copolymer, and to reduce impurities. Another object of the present invention is to provide a method for efficiently producing fluorine-containing copolymer particles having a small amount of residual medium and having good handleability during production (collection).

[0008]

The present invention relates to a method for producing fluorine-containing copolymer particles which can be particularly preferably applied to a suspension polymerization method in water, an organic solvent system precipitation polymerization method and a solution polymerization method.

That is, dispersion stabilization is performed in an aqueous suspension of a polymerization reaction product liquid containing a fluorine-containing copolymer particle produced by polymerizing a mixed monomer containing a fluorine-containing monomer in an organic polymerization medium. A method for producing fluorine-containing copolymer particles, which comprises adding an agent to disperse the fluorine-containing copolymer particles in water, and then distilling off the organic polymerization medium; and a mixed monomer containing a fluorine-containing monomer. Aqueous suspension containing a dispersion stabilizer from a polymerization reaction product solution as an organic polymerization medium solution of a fluorine-containing copolymer or an organic suspension of fluorine-containing copolymer particles produced by polymerizing in an organic polymerization medium Is prepared to disperse the fluorocopolymer in the form of particles in water, and then the organic polymerization medium is distilled off, to a method for producing fluorocopolymer particles.

The dispersion stabilizer used is preferably an emulsifier, more preferably a nonionic emulsifier having an HLB value of 13 or more.

Further, the production method of the present invention is carried out by using a fluorine-containing copolymer particle containing a fluoroolefin monomer unit and a hydrocarbon-based monomer unit, especially tetrahydrofuran (TH
It is particularly suitable for the production of fluorine-containing copolymer particles which are substantially soluble in F).

It is also desirable to add an antifoaming agent when distilling off the polymerization medium.

The present invention also relates to a powder coating resin composition using the fluorine-containing copolymer particles obtained by the above production method.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.

The "aqueous suspension of the polymerization reaction product liquid" in the present invention is a fluorinated copolymer produced by polymerizing a mixed monomer containing a fluorinated monomer in a polymerization medium or particles thereof and the polymerization medium. A polymerization reaction product liquid containing
If the polymerization reaction product liquid is an aqueous suspension of fluorine-containing copolymer particles (suspension polymerization reaction liquid in water), the polymerization reaction product liquid is used as it is for an organic suspension of fluorine-containing copolymer particles (organic precipitation). Polymerization reaction solution) or a homogeneous solution of a fluorine-containing copolymer in an organic polymerization medium (solution polymerization reaction solution), an aqueous solution obtained by mixing the polymerization reaction solution with water (putting it in water or vice versa) It is a suspension. Therefore, an aqueous suspension obtained by, for example, once recovering the copolymer particles and then redispersing the particles in water is out of the scope of the present invention. As such a technique, there is a so-called granulation method as disclosed in Japanese Patent Laid-Open No. 09-376319. Further, the polymerization reaction product liquid obtained by emulsion polymerization itself contains a large amount of dispersion stabilizer (emulsifier), which is different from the production method of the present invention in which a dispersion stabilizer is added after the completion of the polymerization reaction. Is not covered by.

More specifically, for example, in the case of suspension polymerization in water in which polymerization is carried out in water in the presence of an organic solvent,
The resulting polymerization reaction product liquid is in the form of an aqueous suspension of fluorine-containing copolymer particles, and the dispersion stabilizer is added as it is or after adjusting the amount of water to change the concentration of the copolymer particles. .

The organic solvent for suspension polymerization in water is not particularly limited as long as it is an organic solvent that can be used in the suspension polymerization reaction. A solvent that has a small chain transfer reactivity and that completely dissolves the fluorine-containing monomer mixture and the polymerization initiator is preferable, and furthermore, a solvent that hardly swells the obtained fluorine-containing copolymer particles is preferable. Further, from the viewpoint of removing the solvent, a solvent that can be removed at a relatively low temperature below the boiling point of water under heating or under reduced pressure (vacuum) is preferable. Specific examples of such a solvent include, for example, chlorofluorocarbons (CFCs) and hydrochlorocarbons (HCFCs).
Examples thereof include hydrofluorocarbons (HFCs) and hydrofluoroethers (HFC / E) s, which have zero ozone depletion potential and have 2 to 10 carbon atoms, hydrofluorocarbons (HFCs) and hydrofluoroethers (HFCs). / E) are preferably used. From the viewpoints of solvent removability and polymerization pressure, those having 3 to 5 carbon atoms are particularly preferable. Specific examples of such a suitable medium include:
1,1,1,3,3-Pentafluoropropane (HFC245f
a), 1,1,2,2-tetrafluorocyclobutane, CF ₂ H
CF ₂ CF ₂ CF ₂ H, 1,1,1,3,3-pentafluorobutane (HFC365fmc), F (CF ₂ ) ₄ OCH ₃ , (C
Etc. _{F 3) 2 CFOCH 3, H} (CF 2) 3 OCH 3 and the like.

When the fluorine-containing copolymer particles are produced by solution polymerization as reported in Japanese Patent Publication No. 6-104792, the polymerization reaction solution obtained is such that the copolymer is dissolved in an organic solvent. A homogenous solution, for example, a dispersion stabilizer is added to and dispersed in an aqueous suspension obtained by introducing the solution into water. The timing of addition of other dispersion stabilizers will be described later. The organic solvent used in the solution polymerization is preferably a solvent having a boiling point of water or lower and dissolving the copolymer. Examples of such a solvent include ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran, diethyl ether and dipropyl ether; alcohols such as isopropanol and t-butanol; chloroform, dichloromethane,
Halogenated hydrocarbons such as dichloroethane; Esters such as methyl acetate and ethyl acetate; HCFC225CB
Such as fluorocarbons.

Furthermore, in the case of precipitation polymerization in which the copolymer is not dissolved in the solvent but precipitates in the form of particles by polymerization in an organic solvent, the resulting polymerization reaction product liquid is an organic dispersion of the copolymer particles ( Although it is a (suspension) liquid, for example, the dispersion stabilizer is added to a liquid obtained by putting this organic dispersion liquid in water. The timing of addition of other dispersion stabilizers will be described later. Examples of the solvent used in the precipitation polymerization include the solvent used in the above suspension polymerization in water.

Therefore, regardless of which polymerization method is used to produce the fluorinated copolymer, the aqueous suspension comprises the fluorinated copolymer particles and a dispersion medium composed of water and an organic solvent.

However, it is preferable to treat the polymerization reaction product liquid (aqueous suspension) obtained by suspension polymerization, because the reaction rate is high and the removal of heat of polymerization and easy handling are easy.

The concentration of the copolymer particles in the aqueous suspension is
Although it varies depending on the amount of solvent, the amount of copolymer, etc., it is preferably adjusted to the range of 10 to 70% by weight, particularly 30 to 60% by weight.

The particle size of the fluorinated copolymer particles varies depending on the amount of the solvent, the amount of the copolymer, the concentration of the dispersion stabilizer, the stirring speed, the solvent distillation temperature and the like, and is not particularly limited, but usually 0.01 to 5 mm. In particular, it is suitable for producing particles having an average particle size range of 0.01 to 3 mm.

Most of the fluorine-containing copolymers that become a rice cake-like form as described in the above-mentioned prior art are substantially soluble in THF. Therefore, the present invention substantially
It is particularly suitable for the production of fluorine-containing copolymer particles that dissolve in HF.

The phrase "substantially dissolved in THF" as used herein means that 1 g or more of the fluorocopolymer is dissolved in 100 g of THF at a liquid temperature of 25 ° C. In the present invention, the liquid temperature is 25
It is suitable for producing particles of a fluorine-containing copolymer that dissolves in 5 g or more, and further 20 g or more in 100 g of THF at 0 ° C.

As such a fluorine-containing copolymer, a fluorine-containing copolymer containing a fluoroolefin monomer unit and a hydrocarbon monomer unit is preferably mentioned.

Examples of the fluoroolefin monomer include fluorine-containing monomers such as tetrafluoroethylene, chlorotrifluoroethylene, hexafluoropropylene, trifluoroethylene, vinylidene fluoride and pentafluoropropylene. It may be selected as appropriate. These fluoroolefins can be used alone or in combination of two or more.

Examples of hydrocarbon monomers include alkenes such as ethylene, propylene, isobutylene, butylene; vinyl ethers such as ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, isobutyl vinyl ether cyclohexyl vinyl ether; vinyl acetate, vinyl propionate, vinyl butyrate, Vinyl esters such as cyclohexanecarboxylate, vinyl pivalate, vinyl benzoate, vinyl pt-butyl benzoate and vinyl versatate; allyl ethers such as ethyl allyl ether, butyl allyl ether, isobutyl allyl ether, cyclohexyl allyl ether. Allyl alkyl esters such as ethyl allyl ester, butyl allyl ester, cyclohexyl allyl ester; Acryl , Methacrylic acid, ethyl acrylate, butyl acrylate, and esters of acrylic acid or methacrylic acid such as 2-ethylhexyl acrylate and the like.

When it is used as a resin for thermosetting powder coating, a crosslinkable group (hydroxyl group or carboxyl group,
A copolymer obtained by copolymerizing monomers having an amino group, an amide group, a nitrile group, an isocyanate group, etc. is used.

Examples of the monomer having a functional group include hydroxyethyl vinyl ether, hydroxypropyl vinyl ether, hydroxybutyl vinyl ether,
Hydroxyalkyl vinyl ethers such as hydroxyisobutyl vinyl ether and hydroxycyclohexyl vinyl ether; hydroxyalkyl carboxylic acids such as vinyl hydroxyacetate, vinyl hydroxypropioate, vinyl hydroxybutyrate, vinyl hydroxyvalerate, vinyl hydroxyisobutyrate and vinyl hydroxycyclohexanecarboxylate. Of vinyl alcohol with vinyl alcohol;
Hydroxyalkyl allyl ethers such as hydroxyethyl allyl ether, hydroxypropyl allyl ether, hydroxybutyl allyl ether, hydroxyisobutyl allyl ether, hydroxycyclohexyl allyl ether; hydroxyethyl allyl ester, hydroxypropyl allyl ester, hydroxybutyl allyl ester, hydroxyisobutyl allyl Hydroxy allyl esters such as esters and hydroxy cyclohexyl allyl esters; hydroxy alkyl esters of acrylic acid or methacrylic acid such as 2-hydroxyethyl acrylate, hydroxypropyl acrylate, 2-hydroxyethyl methacrylate and hydroxypropyl methacrylate, and the like. Partially fluorine-substituted Things and the like. As the monomer giving the hydroxyl group-containing unit, one or more of these may be selected and used. Further, it is desirable to use a vinyl-based or allyl-based compound because of its copolymerizability with fluoroolefin.

Examples of the monomer having a carboxyl group which may be used in the present invention include (meth) acrylic acid and carboxylalkyl allyl ether.
Examples of the glycidyl group-containing monomer include glycidyl (meth) acrylate, glycidyl vinyl ether, glycidyl allyl ether, and the like. Examples of the monomer having an amino group include aminoalkyl vinyl ether and aminoalkyl allyl ether. Examples of the amide group-containing monomer include (meth) acrylamide and methylol acrylamide. Examples of the monomer having a nitrile group include (meth) acrylonitrile. Examples of the monomer having an isocyanate group include vinyl isocyanate and isocyanate ethyl acrylate.

In addition, ethylene-tetrafluoroethylene copolymer (ETFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE), ethylene-tetrafluoroethylene-hexafluoropropylene copolymer, etc. It is a fluorine-containing copolymer that is substantially insoluble.

The feature of the present invention resides in that an aqueous suspension containing a dispersion stabilizer is prepared from the polymerization reaction product liquid after the completion of the polymerization reaction by once adding the dispersion stabilizer.

Examples of the dispersion stabilizer used in the present invention include, but are not limited to, emulsifiers and water-soluble polymers.

Examples of the emulsifier include polyoxyethylene alkylaryl ethers such as polyoxyethylene nonylphenyl ether; polyoxyethylene lauryl ether, polyoxyethylene oleyl ether,
Polyoxyethylene alkyl ethers such as polyoxyethylene tridodecyl ether and polyoxyethylene 2-ethylhexyl ether; polyoxyethylene alkyl esters such as polyoxyethylene oleate;
Nonionic emulsifiers such as sorbitan derivatives such as polyoxyethylene alkylamines and sorbitan laurate; fatty acid salts such as sodium stearate and potassium oleate; sulfonates such as sodium dodecylbenzene sulfonate; polyoxyethylene nonyl Alkyl sulfates such as phenyl ether sulfate, polyoxyethylene alkyl ether sulfate, sodium lauryl sulfate; anionic emulsifiers such as perfluorooctanoic acid and fluorine-based emulsifiers; alkylamine salts such as laurylamine acetate; lauryl Cationic emulsifiers such as alkylammonium salts such as trimethylammonium chloride, stearyl trimethylammonium chloride; lauryl betaine, stearyl Amphoteric emulsifiers, such as tines; other polyvinyl alcohols, polyvinyl pyrrolidones,
Water-soluble polymers such as polyethylene oxides, celluloses, polyacrylic acids, polymethacrylic acids, polyvinyl pyridines, polyvinyl pyrimidines, sodium polystyrene sulfonate and sodium polyvinyl sulfonate can also be used.

These dispersion stabilizers may be used in one kind or in a mixture of two or more kinds, and the addition amount thereof is 0.001 to 10% by weight, preferably 0.01 to 5% by weight with respect to water. It is selected in the range of%. From the viewpoint of preventing adhesion of the fluorine-containing copolymer particles to the reaction tank wall, stirring blade, etc., and from the viewpoint of easy removal even when adhered, water-soluble polymers and emulsifiers are preferable, and further emulsifiers, and more preferably HLB value is 13
The above nonionic emulsifiers are preferred.

The timing of adding the dispersion stabilizer is not particularly limited as long as it is after the polymerization is completed, and in the case of the polymerization reaction product liquid (aqueous suspension) obtained by the suspension polymerization method in water, the polymerization reaction product liquid is added. The dispersion stabilizer may be added directly to the above, or it may be added after forming an aqueous solution of the dispersion stabilizer. On the contrary, the polymerization reaction product liquid may be added to water containing a dispersion stabilizer, or the dispersion stabilizer may be added after being added to water. In the case of a polymerization reaction product liquid (organic homogeneous solution) obtained by solution polymerization, the polymerization reaction product solution may be added to the dispersion stabilizer-containing water, or the dispersion stabilizer may be added after being added to water. . In addition, after adding the dispersion stabilizer to the polymerization reaction product solution, it may be added to water or water. Of course, an aqueous dispersant solution may be added to the polymerization reaction product solution, or a dispersion stabilizer may be added after adding water. Also in the case of the organic suspension obtained by precipitation polymerization, the organic suspension may be added to the dispersion stabilizer-containing water, or the dispersion stabilizer may be added after the addition to water. In addition, after adding the dispersion stabilizer to the organic suspension, water may be added or water may be added. Of course, the aqueous dispersant solution may be added to the organic suspension, or the dispersion stabilizer may be added after adding water.

The dispersion stabilizer-containing aqueous suspension obtained is then brought into a stable dispersed state by stirring or heating.
Then, the organic solvent in the aqueous suspension is distilled off under stirring and heating. This distillative treatment step can be carried out by heating the aqueous suspension to a temperature not lower than the boiling point of the solvent under normal pressure, or by heating or depressurizing at room temperature. Among these, the method of heating under normal pressure or reduced pressure is preferable from the viewpoint of solvent recovery and reuse. The heating temperature is not less than the boiling point of the solvent and not more than the boiling point of water, preferably about the boiling point of the solvent + about 20 to 30 ° C. When the organic polymerization solvent used in the solution polymerization or precipitation polymerization method is a water-soluble solvent, it can be removed by washing with water.

When the dispersion stabilizer is not added, the fluorine-containing copolymer particles are aggregated and adhered to each other in the step of distilling off the organic solvent, and fused to form a large mass like a rice cake. Even if the organic solvent is distilled off, the copolymer particles do not agglomerate or coalesce and are obtained in the form of particles.

Further, it is preferable to add an antifoaming agent in order to prevent foaming by the dispersion stabilizer when the organic solvent is distilled off. The defoaming agent is not particularly limited as long as it is an aqueous defoaming agent. Specific examples include surfactant type defoaming agents such as emulsion type or self-emulsifying type silicone defoaming agents, polyethers, metal soaps, fatty acid esters, higher alcohols; mineral oil defoaming agents such as waxes and mineral oils. Examples include foaming agents. The addition amount of the defoaming agent is appropriately adjusted depending on the kind and addition amount of the dispersion stabilizer.

After distilling off the organic solvent, the copolymer particles are washed, dehydrated and dried to obtain a fluorine-containing copolymer powder which can be used as a raw material for powder coating, for example. can do.

The dispersion stabilizer adhering to the copolymer particles may adversely affect the physical properties of the coating film formed later, so it is desirable to remove it as much as possible. The residual dispersion stabilizer can be removed by various solvents or water, but it is preferable to remove it by washing with water or warm water because it is easy to handle and is easily removed by washing.

Further, if the antifoaming agent also remains in the copolymer particles, it may adversely affect the physical properties of the coating film, so it is desirable to remove it as much as possible. The defoaming agent can be removed by the above-mentioned method, like the dispersion stabilizer.

The fluorine-containing copolymer particles produced by the production method of the present invention can be used for various purposes by granulating the particles as they are or by a conventional method and granulating if necessary.

It is particularly useful as a resin for powder coating obtained by the production method of the present invention, and if necessary, it has an average particle size of 20-80.
It can be used as a fluororesin powder clear paint by adjusting to the range of μm. The present invention also relates to such a fluororesin powder coating material.

The fluororesin powder coating material of the present invention comprises, in addition to the fluorocopolymer resin particles obtained by the production method of the present invention,
Various additives usually added to powder coatings can be added. Examples of such additives include color pigments (inorganic pigments such as titanium dioxide, red iron oxide, yellow iron oxide, carbon black, etc., and organic pigments such as phthalocyanine blue, phthalocyanine green, indolinone, quinacridone, anthraquinone, various organic metal complexes), extender pigments. (Calcium carbonate, talc, silica, etc.), metal powder (aluminum powder, stainless powder), mica powder, leveling agent, ultraviolet absorber, antifoaming agent, heat deterioration preventing agent and the like. One or two of these additives may be added as required.
It is possible to mix one or more kinds.

When a cross-linking site is introduced into the fluoropolymer, a curing agent is added. As the curing agent, those conventionally used in thermosetting powder coatings can be used and are appropriately selected depending on the type of crosslinking site, baking temperature and the like.
For example, a blocked isocyanate compound, an acid anhydride,
Examples thereof include polyamine compounds, isocyanurate compounds, and polybasic acids.

[0048]

EXAMPLES The present invention will be described below with reference to examples.
The invention is not limited to only such embodiments.

Comparative Synthesis Example 1 (Suspension Polymerization) A glass autoclave having a volume of 4 liters was charged with 760 g of deionized water and 7.6 g of potassium carbonate, followed by nitrogen substitution and vacuum deaeration to remove dissolved oxygen. Then, 570 g of HCFC141b which is a polymerization solvent, 340 g of hexafluoropropylene (HFP), 3.1 g of hydroxybutyl vinyl ether and 1.6 g of vinyl t-butylbenzoate were charged, and the temperature was adjusted to 35 ° C. Then, a mixed monomer gas of tetrafluoroethylene (TFE) / ethylene (Et) (composition 82/18 mol%) was introduced and the mixture was mixed with 0.2.
After increasing the pressure to 9 MPaG, 20 g of a 25% HCFC225CB solution of Perloyl IB (manufactured by NOF Corporation) as a polymerization initiator was charged to start the reaction. During the reaction, the pressure of the reaction vessel was kept at 0.9 MPaG by continuously supplying a mixed monomer gas of TFE / Et / HFP (composition 45/39/16 mol%). Further, liquid monomers such as hydroxybutyl vinyl ether and vinyl t-butyl benzoate were continuously supplied according to the consumption of the mixed monomer gas. After carrying out the reaction for 5 hours, the supply of the mixed monomer gas was stopped, the residual gas monomer was released, and the polymerization solvent was distilled off at 50 ° C. to stop the reaction. When the state of the copolymer particles was confirmed by opening the autoclave,
It was a mochi-like mass. The dough-like mass was crushed, washed, and dried to give fluorocopolymer particles (particle size range: about 0.01 to 2 mm) (yield 98 g). This pulverized powder is referred to as "B-1". The glass transition temperature of the obtained fluorocopolymer was 52 ° C., and the number average molecular weight (converted to standard polystyrene) measured by size exclusion chromatography was 17,000. ¹ H-NMR, ¹⁹ F
-The composition of the copolymer calculated from NMR and elemental analysis is TFE / Et / HFP / hydroxybutyl vinyl ether / pt-butyl vinyl benzoate = 32/37/1
It was 4/8/9 mol%. Further, 20 g of the fluorine-containing copolymer particles was put into 100 g of THF and stirred at 25 ° C., and completely dissolved.

Synthetic Example 1 (Suspension Polymerization) After reacting for 6 hours in the same manner as in Synthetic Example 1 except that HCFC141b of Comparative Synthetic Example 1 was changed to HFC245fa, residual gas monomer was released (polymerization solvent was distilled off). Then, the polymerization reaction was stopped and a polymerization reaction product liquid of the fluorine-containing copolymer particles was obtained. A part of the obtained polymerization reaction product liquid of the fluorocopolymer was taken out, reprecipitated in hexane to remove unreacted monomers, and dried to obtain fluorocopolymer particles for analysis. The glass transition temperature of this fluorinated copolymer was 54 ° C, and the number average molecular weight (converted to standard polystyrene) by size exclusion chromatography was 20.
It was 000. The composition of the copolymer calculated from ¹ H-NMR, ¹⁹ F-NMR and elemental analysis was TFE / Et /
HFP / hydroxybutyl vinyl ether / pt-butyl vinyl benzoate = 34/35/13/8/10 mol%
Met. Further, 20 g of the fluorine-containing copolymer particles are
When it was put in 100 g of HF and stirred at 25 ° C., it was completely dissolved.

Synthesis Example 2 (Suspension Polymerization) HCFC141b of Comparative Synthesis Example 1 was replaced with HFC365fmc.
After reacting for 6 hours in the same manner as in Synthesis Example 1 except that the polymerization reaction was stopped by releasing the residual gas monomer (without distilling off the polymerization solvent), the polymerization reaction of the fluorine-containing copolymer particles was performed. A product solution was obtained. A part of the obtained polymerization reaction product liquid of the fluorocopolymer was taken out, reprecipitated in hexane to remove unreacted monomers, and dried to obtain fluorocopolymer particles for analysis. The glass transition temperature of this fluorinated copolymer was 56 ° C., and the number average molecular weight (converted to standard polystyrene) by size exclusion chromatography was 1
It was 7,000. The composition of the copolymer calculated from ¹ H-NMR, ¹⁹ F-NMR and elemental analysis was TFE / Et.
/ HFP / hydroxybutyl vinyl ether / pt-butyl vinyl benzoate = 34/34/15/8/8/9 mol%
Met. Further, 20 g of the fluorine-containing copolymer particles are
When it was put in 100 g of HF and stirred at 25 ° C., it was completely dissolved.

Synthesis Example 3 (Solution Polymerization) In a stainless steel pressure-resistant reactor equipped with a stirrer having an internal volume of 4 liters, 2100 g of HCFC225CB, 213 g of cyclohexyl vinyl ether, 120 g of isobutyl vinyl ether, 333 g of hydroxybutyl vinyl ether, and potassium carbonate were added. 13 g and 1 g of azobisisobutyronitrile were charged, and nitrogen substitution and vacuum deaeration were performed to remove dissolved oxygen. Then, 667 g of chlorotrifluoroethylene (CTFE) was introduced into the pressure vessel, the temperature was gradually raised, and the reaction was continued under stirring while maintaining the temperature at 65 ° C. After 10 hours, the reactor was cooled with water to stop the reaction, and after cooling to room temperature, unreacted monomers were extracted,
The reactor was opened. A part of the obtained polymerization reaction product liquid of the fluorocopolymer was taken out, reprecipitated in hexane to remove unreacted monomers, and dried to obtain fluorocopolymer particles for analysis. The fluorine-containing copolymer particles had a glass transition temperature of 45 ° C. and a number average molecular weight (converted to standard polystyrene) of 50,000 by size exclusion chromatography. The composition of the copolymer calculated from ¹ H-NMR, ¹⁹ F-NMR and elemental analysis was CTFE / cyclohexyl vinyl ether / isobutyl vinyl ether / hydroxybutyl vinyl ether = 50/16/9/25 mol%. Further, 20 g of the fluorine-containing copolymer particles was put into 100 g of THF and stirred at 25 ° C., whereupon it completely dissolved.

Example 1 In Synthesis Example 1, after the completion of polymerization, residual gas monomers were further released until the pressure in the autoclave reached about 0.3 MPaG, and then HL was added to the polymerization reaction product liquid (aqueous suspension).
Polyethylene glycol lauryl ether having a B value of 18.1 (hereinafter referred to as "PEG-LE") (Emulgen 130K manufactured by Kao Corporation, trade name) / ion-exchanged water / silicone antifoaming agent (antifoam EPL.Dow) (Made by Corning) was added to the autoclave so that the concentration of PEG-LE was 2% by weight with respect to water and the concentration of the defoaming agent was 0.2% by weight, and the mixture was stirred and dispersed in the suspension. It was Then 45
Residual gas monomer and polymerization solvent (HFC
245fa) was distilled off to obtain a dispersion liquid of fluorine-containing copolymer particles. When the solvent was distilled off, the polymerization solvent could be easily recovered with little foaming of the aqueous dispersion. The obtained fluorine-containing particles were granular with a particle size range of 0.01 to 1 mm, and almost no moistened or agglomerated particles were observed. The fluorine-containing copolymer particles were taken out from the dispersion liquid of the copolymer particles by filtration,
It was washed with water and dried with a warm air dryer at 50 ° C. for 24 hours to obtain a white powder of a fluorinated copolymer. This powder is referred to as "A-
1 ”.

Example 2 A fluorinated copolymer was prepared in the same manner as in Example 1 except that the concentration of PEG-LE was 0.5% by weight with respect to water, and no defoaming agent was added. The particles were dispersed.
Then, the mixture was heated to 45 ° C. to distill off the residual gas monomer and the polymerization solvent (HFC245fa) to obtain fluorine-containing copolymer particles. Foaming was observed in the aqueous dispersion upon evaporation, but the obtained fluorocopolymer particles had a particle size range of about 0.0.
The particles were fine particles of 1 to 2 mm, and no moistened or lumped particles were observed. The fluorocopolymer particles were taken out from the dispersion liquid of the copolymer particles by filtration, washed with water, and dried at 50 ° C. for 24 hours in a warm air dryer to obtain a white powder of the fluorocopolymer. . This powder is designated as "A-2".

Example 3 In Synthesis Example 2, after completion of the polymerization, residual gas monomers were further released until the pressure in the autoclave reached about 0.3 MPaG, and then PE was added to the polymerization reaction product liquid (aqueous suspension).
A mixture of G-LE / ion-exchanged water / silicone antifoaming agent (anti-foam EPL, manufactured by Dow Corning) was PEG-
LE concentration is 2% by weight of water, defoamer concentration is 0.2% by weight
The resulting mixture was added to the autoclave and stirred to disperse it in the suspension. Then, the pressure is reduced under heating at 40 ° C. and the residual gas monomer and the polymerization solvent (HFC365fm
c) was distilled off to obtain a dispersion liquid of fluorine-containing copolymer particles.
When the solvent was distilled off, the polymerization solvent could be easily recovered with little foaming of the aqueous dispersion. The obtained fluorine-containing particles were granular with a particle size range of 0.01 to 1.5 mm, and almost no moistened or lumped particles were observed. The fluorocopolymer particles were taken out from the dispersion liquid of the copolymer particles by filtration, washed with water, and dried at 50 ° C. for 24 hours in a warm air dryer to obtain a white powder of the fluorocopolymer. . This powder is referred to as "A-
3 ”.

Example 4 Fluorine-containing copolymer particles were dispersed in the same manner as in Example 1 except that sodium lauryl sulfate (hereinafter referred to as “SDS”) was used as the dispersion stabilizer instead of PEG-LE. It was Then, the mixture was heated to 45 ° C. to distill off the residual gas monomer and the polymerization solvent (HFC245fa) to obtain fluorine-containing copolymer particles. At the time of distillation, the aqueous dispersion did not foam much and the polymerization solvent could be easily recovered. The obtained fluorinated copolymer particles were in the form of particles having a particle size range of about 0.01 to 1 mm, and almost no moistened or lumped particles were observed. The fluorocopolymer particles were taken out from the dispersion liquid of the copolymer particles by filtration, washed with water, and dried at 50 ° C. for 24 hours in a warm air dryer to obtain a white powder of the fluorocopolymer. . This powder is designated as "A-4".

Example 5 In Example 1, instead of PEG-LE as a dispersion stabilizer, polyvinyl alcohol (polymerization degree: 500; hereinafter, referred to as “P”) was used.
Fluorine-containing copolymer particles were dispersed in the same manner except that "VA500") was used. Then, the mixture is heated to 45 ° C. and residual gas monomer and polymerization solvent (HFC245f
The a) was distilled off to obtain fluorine-containing copolymer particles. At the time of distillation, the aqueous dispersion did not foam much and the polymerization solvent could be easily recovered. The obtained fluorocopolymer particles were in the form of particles having a particle size range of about 0.01 to 3 mm, and almost no cake-like or lump-like particles were observed. The fluorine-containing copolymer particles were taken out from the dispersion liquid of the copolymer particles by filtration,
It was washed with water and dried with a warm air dryer at 50 ° C. for 24 hours to obtain a white powder of a fluorinated copolymer. This powder is referred to as "A-
5 ".

Example 6 Synthesis Example 3 in a 1-liter pressure-resistant glass autoclave
200 g of the polymerization reaction product solution obtained by the (solution polymerization method) was added to 500 g of water, SDS was added to have a concentration of 1% by weight with respect to water, and the mixture was stirred to disperse the fluoropolymer. Then, a mixed solution of SDS / ion-exchanged water / silicon antifoaming agent was added into the autoclave so that the SDS concentration was 2% by weight with respect to water and stirred to disperse the fluorine-containing copolymer particles. Then, the pressure was reduced under heating at 40 ° C. and the residual gas monomer and the polymerization solvent (HCFC225CB) were distilled off to obtain fluorine-containing copolymer particles. No bubbling was observed in the aqueous dispersion upon evaporation. The obtained fluorine-containing copolymer particles were in the form of particles having a particle size range of about 0.1 to 4 mm, and almost no cake-like or lump-like particles were observed. The fluorocopolymer particles were taken out from the dispersion liquid of the copolymer particles by filtration, washed with water, and dried at 50 ° C. for 24 hours in a warm air dryer to obtain a white powder of the fluorocopolymer. . This powder is designated as "A-6".

Table 1 shows the conditions and results in Examples 1 to 6 and Comparative Synthesis Example 1.

[0060]

[Table 1]

Examples 7 to 13 (Physical properties of coating film) All the components of the composition shown in Table 2 were put in a polyethylene bag, mixed by shaking, and then a twin-screw melt kneader (16 mm twin extruder manufactured by Prism). After melt-kneading at 135 ° C. at 100 ° C., cooling, and fine pulverization at room temperature with a universal pulverizer (manufactured by IKA). Then, classification was performed with a 150-mesh wire mesh to produce each powder coating composition.

This powder coating composition is coated on a chemical conversion treated aluminum plate by an electrostatic coating method (coating condition: corona type powder coating gun. GX30 manufactured by Onoda Cement Co., Ltd.).
0, applied voltage 60 kV), and baked at 200 ° C. for 15 minutes to obtain a cured coating film. The physical properties of this cured coating film were examined. The results are shown in Table 2.

The additives used in Table 2 are TYPURE-R960 (trade name) manufactured by DuPont as titanium oxide, and B-1530 manufactured by Degussa Hüls which is ε-caprolactam blocked isocyanate as a curing agent.
(Trade name) and Modaflow (trade name) manufactured by Monsanto Co. were used as a leveling agent.

The physical properties of the coating film were examined for the following items.

(Cured film thickness) Eddy current type film thickness meter EL10D
(Manufactured by Sankou Electronic Laboratory Co., Ltd.).

(Appearance of coating film) When a fluorescent lamp is projected on a coated article, the shape of the fluorescent lamp reflected on the surface of the coating film is visually observed.
Evaluation is A: no distortion, B: very slight distortion,
C: Slightly distorted, D: Largely distorted.

(Gloss) According to JIS K5400-6.1, the 60 degree specular gloss is examined.

(Pencil Hardness) The pencil hardness is measured according to JIS K5400.

(Impact resistance) AAMA (American Archite
ctural Manufacturers Association) standard AAMA2
After performing a falling ball test according to 605, a tape peeling test is performed. The evaluation is ○: there is no cracking or peeling of the coating film,
X: The coating film was cracked or peeled.

(Adhesion) A goose-eye test is performed in accordance with AAMA2605.

(Stain resistance) Oil-based ink (red) on the surface of the coating film
Is applied and left at room temperature for 24 hours, and then wiped off with a cloth impregnated with ethanol, and the color difference (ΔE) before and after ink application is measured with a color difference meter. The evaluation was that A: ΔE was less than 1, B: ΔE was 1 or more and less than 5, and C: ΔE was 5 or more.

(Weather resistance) An accelerated weather resistance tester (Sunshine Weatherometer) was used to examine the gloss retention rate after 2000 hours.

[0073]

[Table 2]

As shown in Table 2, even if the powder obtained by the production method of the present invention is used as it is in the powder coating, the characteristics of the coating film are not deteriorated. In addition, in the example using the powder (A-6) obtained by the solution polymerization method (Example 6), the stain resistance is lowered, but the type of fluoroolefin is different (the fluorine content is different). It is thought that the cause is.

[0075]

According to the present invention, after the completion of the polymerization reaction of the mixed monomer containing the fluorine-containing monomer, the obtained fluorine-containing copolymer particles are not aggregated or dough-like, Can be collected. The fluorine-containing copolymer particles have a small amount of residual air solvent for polymerization, and can be used as they are as a raw material for powder coatings, and the resulting coating film physical properties are improved.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Ryoichi Fukagawa             Daiichi Nishiichitsuya 1-1, Settsu City, Osaka Prefecture             Yodogawa Manufacturing Co., Ltd. (72) Inventor Daisuke Tanizawa             Daiichi Nishiichitsuya 1-1, Settsu City, Osaka Prefecture             Yodogawa Manufacturing Co., Ltd. F term (reference) 4J100 AA02Q AA03Q AA04Q AA06Q                       AC22P AC24P AC25P AC26P                       AC27P AC31P AE02Q AE04Q                       AE13Q AG02Q AG04Q AG10Q                       AJ02Q AL03Q CA01 CA04                       DA39 GC07 GC22 GC26 JA01

Claims (6)

[Claims] 1. Stabilization of dispersion in an aqueous suspension of a polymerization reaction product liquid containing fluorine-containing copolymer particles produced by polymerizing a mixed monomer containing a fluorine-containing monomer in an organic polymerization medium, and an organic polymerization medium. A method for producing fluorine-containing copolymer particles, which comprises adding an agent to disperse the fluorine-containing copolymer particles in water, and then distilling off the organic polymerization medium. 2. Polymerization of a fluorocopolymer produced by polymerizing a mixed monomer containing a fluoromonomer in an organic polymerization medium as an organic polymerization medium solution or an organic suspension of fluorocopolymer particles. A fluorinated copolymer characterized in that an aqueous suspension containing a dispersion stabilizer is prepared from a reaction product solution and the fluorinated copolymer is dispersed in water in the form of particles, and then the organic polymerization medium is distilled off. Particle manufacturing method. 3. The dispersion stabilizer is an emulsifier.
Or the production method described in 2. 4. The method according to claim 1, wherein the dispersion stabilizer is a nonionic emulsifier having an HLB value of 13 or more. 5. The production method according to claim 1, wherein the fluorine-containing copolymer contains a fluoroolefin monomer unit and a hydrocarbon-based monomer unit and is substantially dissolved in tetrahydrofuran. 6. The method according to claim 1, wherein an antifoaming agent is added when the polymerization medium is distilled off.