JPH04270748A - Aqueous dispersion - Google Patents

Abstract

PURPOSE:To obtain an aqueous dispersion suitable as an aqueous coating compound, having excellent film-forming properties, improved mechanical performance, water resistance and stain removal property in coating film and excellent stability during polymerization and storage by dispersing a specific fluorine- containing copolymer into water. CONSTITUTION:(A) 20-80mol% fluoroolefin (preferably 2-4C perfluoroolefin), (B) 0.1-25mol% hydrophilic site-containing macromonomer, preferably polyether containing a radically polymerizable unsaturated group at one end, especially polyoxyethylene, (C) 0.01-20wt.% monomer containing >=2 polymerizable functional groups, such as divinyl ether shown by formula I (R is 1-20C straight- chain, branched or cyclic alkylene group) or vinyl allyl ether shown by formula II and optionally 0-30mol% monomer containing hydroxyl group, carboxylic group, epoxy group, etc., are subjected to emulsion polymerization in an aqueous medium by adding a polymerization initiator (e.g. aluminum persulfate), a pH adjuster (e.g. sodium carbonate), etc., to give the objective aqueous dispersion.

Description

[Detailed description of the invention]

0001

FIELD OF THE INVENTION This invention relates to aqueous dispersions.

0002

[Prior Art] Conventionally, copolymers consisting of fluoroolefins, cyclohexyl vinyl ether, and various other monomers are soluble in organic solvents at room temperature, and when used as paints, they are transparent and have high gloss. It is known that it provides a coating film with the excellent properties of fluororesin, such as high weather resistance, water and oil repellency, stain resistance, and non-adhesion (for example, Japanese Patent Application Laid-Open No. 55-44083), and is used in construction, etc. Its use is increasing in the field of

On the other hand, in recent years, the use of hydrophilic organic solvents has been regulated from the perspective of air pollution, so demand for water-based paints and powder paints that do not use hydrophilic organic solvents is increasing. Studies have also been conducted on fluororesins, and it has been reported that those without functional groups can be produced by emulsion polymerization (Japanese Patent Application Laid-Open No. 55-25411).

[0004] Furthermore, a product obtained by emulsion polymerization of a fluorine-containing copolymer having a hydroxyl group is disclosed in JP-A-57-3410.
7, JP-A No. 61-231044. However, these methods have problems in that an aqueous dispersion cannot be obtained, or even if an aqueous dispersion is obtained, it has extremely poor mechanical and chemical stability and causes aggregation and sedimentation during storage.

Furthermore, the aqueous dispersions obtained by these methods have problems such as the resulting coating films have poor water resistance, are susceptible to whitening, and are difficult to remove stains from.

[0006]

SUMMARY OF THE INVENTION The present invention aims to solve the problems of the prior art described above. That is, the object is to provide an aqueous dispersion that has excellent film-forming properties, excellent mechanical performance and water resistance of the coating film, good stain removal properties, and is stable during polymerization and storage.

[0007]

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and includes a polymerized unit based on a fluoroolefin, a polymerized unit based on a macromonomer having a hydrophilic site, and a polymerized unit based on a macromonomer having a hydrophilic site. The object of the present invention is to provide an aqueous dispersion in which a fluorine-containing copolymer whose essential component is a polymerized unit based on a monomer having two or more functional groups is dispersed in water.

In the present invention, as the fluoroolefins, fluoroolefins having about 2 to 4 carbon atoms such as vinylidene fluoride, trifluoroethylene, chlorotrifluoroethylene, tetrafluoroethylene, pentafluoropropylene, and hexafluoropropylene are preferably employed. be done. Particularly preferred are perhaloolefins.

In the aqueous dispersion of the present invention, it is important that the fluorine-containing copolymer has polymerized units based on macromonomers having hydrophilic sites. Since this unit is included as an essential component of the fluorine-containing copolymer, it not only improves the mechanical and chemical stability of the aqueous dispersion, but also improves film-forming properties and water resistance of the coating film. It is possible.

Furthermore, in the aqueous dispersion of the present invention, it is important that the fluorine-containing copolymer has polymerized units based on monomers having two or more polymerizable functional groups. Since this unit is included as an essential component of the fluorine-containing copolymer, not only the water resistance and stain removal properties of the coating film are improved, but also the surface hardness and chemical resistance are improved.

In the present invention, the hydrophilic site of the macromonomer having a hydrophilic unit refers to a site having a hydrophilic group,
or a site having a hydrophilic bond, or a site consisting of a combination thereof. This hydrophilic group may be ionic, nonionic, amphoteric, or a combination thereof; however, in the case where the hydrophilic site consists only of units having an ionic hydrophilic group, Unfavorable because of problems with the chemical stability of aqueous dispersions;
It is desirable to combine with a site having a nonionic or amphoteric hydrophilic group, or a site having a hydrophilic bond.

[0012] Furthermore, the macromonomer refers to a low molecular weight polymer or oligomer having a radically polymerizable unsaturated group at one end. That is, it is a compound having a radically polymerizable unsaturated group at one end and at least two repeating units. It varies depending on the type of repeating unit, but
Usually, those having 100 or less repeating units are preferably employed from the viewpoint of polymerizability, water resistance, etc.

Examples of macromonomers having a hydrophilic site include (1) CH2=CHO(CH2)k[O(CH2)m
]nOX (k is 1 to 10, m is 1 to 4, n is 2 to
(2) CH2=CHCH2O(CH2)k[O(CH
2) m]nOX(k, m, n, X is (1)
(3) CH2=CHO(CH
2) k(OCH2CH2)m(OCH2CH(CH3)
) nOX (k is 1 to 10, m is 2 to 20, n is an integer of 0 to 20, X is H or a lower alkyl group, and the oxyethylene units and oxypropylene units can be arranged in either block or random format. (4) CH2=CHCH2O(CH2)k(OCH2
CH2)m (OCH2CH(CH3))nOX (
k, m, n, and X are the same as those in formula (3), and the oxyethylene units and oxypropylene units may be arranged in either block or random manner)
(5) CH2=CHO(CH2)nO(C(O)(C
H2) mO) kH (n is 1 to 10, m is 1 to 1
Examples thereof include polyether polyesters having a radically polymerizable unsaturated group at one end, such as (0, k = 1 to 30).

Among these, those having a vinyl ether type structure at one end are preferably employed because they have excellent copolymerizability with fluoroolefins. In particular, polyether chain portions consisting of oxyethylene units or oxyethylene units and oxypropylene units are preferred because they have excellent hydrophilicity.

[0015] Furthermore, at least 2 oxyethylene units
Unless they are unique, properties such as stability cannot be achieved. Furthermore, if the number of oxyalkylene units is too large, the water resistance and weather resistance of the coating film will deteriorate, which is not preferable.

[0016] Such a macromonomer having a hydrophilic moiety can be produced by a method such as polymerizing a vinyl ether or allyl ether having a hydroxyl group with formaldehyde or a diol, or ring-opening polymerizing an alkylene oxide or a compound having a lactone ring. is possible.

Further, as a macromonomer having a hydrophilic site, a hydrophilic ethylenically unsaturated monomer having a radically polymerized chain and having a radically polymerizable unsaturated group such as vinyl ether or allyl ether at the end can be used. There may be.

[0018] Such a macromonomer has been described by Yamashita et al.
olym. Bull. ,5. 335 (1981). That is,
A polymer having a condensable functional group is produced by radically polymerizing an ethylenically unsaturated monomer having a hydrophilic group in the presence of an initiator having a condensable functional group and a chain transfer agent; Examples include a method in which a compound such as glycidyl vinyl ether or glycidyl allyl ether is reacted with a functional group to be combined to introduce a radically polymerizable unsaturated group at the end.

Ethylenically unsaturated monomers used in the production of this macromonomer include acrylamide, methacrylamide, N-methylol acrylamide, N-
Methylol methacramide, 2-methoxyethyl acrylate, 2-methoxyethyl methacrylate, diacetone acrylamide, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, polyhydric alcohol acrylic acid Examples include esters, methacrylic acid esters of polyhydric alcohols, and vinylpyrrolidone. In addition, copolymerizable monomers include acrylamide and its derivatives, methacrylamide and its derivatives, N-methylol acrylamide derivatives, ethyl carbitol acrylate, methyl triglycol acrylate, 2-hydroxyethyl acryloyl phosphate, butoxyethyl acrylate. and so on.

[0020] Initiators used in the production of this macromonomer include 4,4'-azobis-4-cyanovaleric acid, 2,2'-azobis-2-amidinopropane hydrochloride, potassium peroxide, and ammonium peroxide. , azobisisobutyronitrile, and benzoyl peroxide.

Monomers having two or more polymerizable functional groups are preferably monomers having a vinyl ether group, allyl ether group, or isopropenyl ether group at one end from the viewpoint of copolymerizability with other monomers. , which has a polymerizable double bond at the other end. Further, it is preferable that the double bonds at both ends have different polymerizability.

Specific monomers having two or more polymerizable functional groups include divinyl ethers represented by the following formula, CH
2=CHO-R-OCH=CH2 (R has 1 or more carbon atoms
(20 linear, branched or cyclic alkylene groups, the same applies hereinafter) vinyl ether allyl ethers represented by the following formula, CH
2=CHO-R-OCH2CH=CH Allyl vinyl ethers represented by the secondary formula, CH2=CHO-R-CH2
CH=CH2 Also,


CH2=CHOCH=CH2 CH2=CHCOO-R-OCH=CH2 CH2=C
(CH3)COO-R-OCH=CH2 CH2=CH
COO-R-OCOCH=CH2 CH2=C(CH3
)COO-R-OCOC(CH3)=CH2 CH2=
C(CH3)COO-R-OCOCH=CH2 CH2
=CH-R-CH=CH2 and the like are exemplified.

The fluorine-containing copolymer of the present invention contains polymerized units containing reactive groups selected from hydroxyl groups, epoxy groups, carboxylic acid groups, carbonyl groups, and hydrazine residues in addition to the above three types of units. May contain.

The stability of the aqueous dispersion of the present invention is not impaired even if the fluorine-containing copolymer has a reactive group. In addition, when the fluorine-containing copolymer has a reactive group, it has the advantage that when used as a paint base, a coating film with extremely excellent water and solvent resistance can be obtained by using a curing agent. .

[0025] Furthermore, the polymerized unit containing a hydroxyl group can be obtained by copolymerizing a hydroxyl group-containing monomer, or by subjecting a polymer to a polymer reaction to form a unit containing a hydroxyl group. . Here, the hydroxyl group-containing monomers include hydroxyalkyl vinyl ethers such as hydroxybutyl vinyl ether, hydroxyalkyl allyl ethers such as hydroxyethyl allyl ether, hydroxyl groups of acrylic acid or methacrylic acid such as hydroxyethyl acrylate, and hydroxyethyl methacrylate. Examples include alkyl esters, hydroxyalkyl vinyl esters, and hydroxyalkyl allyl esters.

[0026] In addition, as a method for forming a unit containing a hydroxyl group by subjecting a polymer to a polymer reaction, after copolymerizing a vinyl ester that can be hydrolyzed after polymerization,
Examples include a method of hydrolysis to form a hydroxyl group.

The polymerized unit containing a carboxylic acid group can be obtained by copolymerizing a monomer containing a carboxylic acid group, or by reacting a dibasic acid anhydride with a polymer having a hydroxyl group to form a carboxylic acid group. There is a way to do it.

Here, as the carboxylic acid group-containing monomer, CH2=CHOR1OCOR2COOMCH2=CHC
H2R3OCOR4COOM (R1 and R3 have 2 carbon atoms
-15 alkyl groups, R2 and R4 are saturated or unsaturated linear or cyclic hydrocarbon groups, and M is a group containing hydrogen, an alkali metal or nitrogen. ) etc. are exemplified.

Polymerized units containing epoxy groups can be introduced by copolymerizing monomers containing epoxy groups.

Examples of monomers containing epoxy groups include epoxy group-containing alkyl vinyl ethers such as glycidyl vinyl ether, epoxy group-containing alkyl allyl ethers such as glycidyl allyl ether, glucidyl acrylate, glucidyl methacrylate, etc. Examples include epoxy group-containing alkyl acrylates or methacrylates.

Further, a carbonyl group can be introduced by copolymerizing a carbonyl group-containing monomer, and a hydrazine residue can be introduced by copolymerizing a carbonyl group-containing monomer with dicarboxylic acid dihydrazide (for example, isophthalic acid dihydrazide, adipic acid dihydrazide). ) or hydrazine hydrate in an amount of 0.02 to 1 mole per mole of carbonyl group, and the mixture is heated to react.

The fluorine-containing copolymer of the present invention may contain, in addition to the above units, units based on monomers copolymerizable with these units.

Examples of such monomers include olefins such as ethylene and propylene, vinyl ethers such as ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, and cyclohexyl vinyl ether, vinyl esters such as butanoic acid vinyl ester and octoic acid vinyl ester, Examples include vinyl compounds such as aromatic vinyl compounds such as styrene and vinyltoluene, allyl compounds such as ethyl allyl ether, acryloyl compounds such as butyl acrylate, and methacryloyl compounds such as ethyl methacrylate.

In particular, olefins, vinyl ethers,
Vinyl esters, allyl ethers, and allyl esters are preferably employed. Here, the olefins are preferably those having about 2 to 10 carbon atoms, and the vinyl ethers, vinyl esters, allyl ethers, and allyl esters are preferably linear, branched, or alicyclic ones having about 2 to 15 carbon atoms. Those having an alkyl group of are preferably employed. In such a monomer, at least a portion of hydrogen bonded to carbon may be replaced with fluorine.

The fluorine-containing copolymer of the present invention has a proportion of 20 to 80 mol% of polymerized units based on fluoroolefins and 0.1 to 25 mol% of polymerized units based on macromonomers having hydrophilic sites. It is preferable that there be. If the amount of polymerized units based on fluoroolefins is too small, weather resistance will not be sufficiently exhibited, and if it is too large, water dispersibility will be extremely poor, which is not preferable. Especially from 30~
Preferably it is 70 mol%. Further, if the polymerized unit based on a macromonomer having a hydrophilic site is too small, the water dispersibility will be extremely poor, and if it is too large, the weather resistance and water resistance of the coating film will be deteriorated, which is not preferable. In particular, in order to achieve an extremely excellent effect on film forming properties, it is preferable that this unit is contained in a proportion of 0.3 to 20 mol %.

Further, the amount of polymerized units based on monomers having two or more polymerizable functional groups is preferably 20 mol % or less. If the proportion of this unit is too large, the film-forming properties will deteriorate and the coating film may become hard and brittle when cured, which is not preferable. Furthermore, if the proportion of this unit is too small, water resistance, stain removal properties, surface hardness, chemical resistance, etc. will not be sufficiently improved, which is not preferable. Preferably, this unit is contained in a proportion of 0.01 to 10 mol%.

Further, when a polymerized unit containing a reactive group is contained, it is preferably 25 mol % or less. If the proportion of this unit is too large, the water dispersibility will decrease and the coating film may become hard and brittle when cured, which is not preferable.

The content of units other than the polymerized units based on the fluoroolefins and the polymerized units based on the macromonomer having a hydrophilic site is preferably 70 mol % or less. If this unit is too large, weather resistance will deteriorate, which is not preferable.

The aqueous dispersion of the present invention is one in which the above fluorine-containing copolymer is dispersed in water. Furthermore, the aqueous dispersion of the present invention exhibits excellent mechanical and chemical stability.

[0040] When an emulsifier is used here, anionic, cationic, nonionic, amphoteric, nonionic-cationic, nonionic-anionic, or one having a reactive group is used alone or in combination. be able to. When using a hydrophilic organic solvent, it is preferably 20% by weight or less from the viewpoint of safety.

The aqueous dispersion of the present invention can be produced by emulsion polymerization of a fluoroolefin, a macromonomer having a hydrophilic moiety, and, if necessary, other monomers in an aqueous medium. The initiation of emulsion polymerization is carried out by adding a polymerization initiator in the same manner as the initiation of ordinary emulsion polymerization. As such a polymerization initiator, an ordinary radical initiator can be used, but a water-soluble initiator is preferably employed, and specifically, a persulfate such as ammonium persulfate, hydrogen peroxide, or a combination of these and sodium bisulfite is used. , redox initiators in combination with reducing agents such as sodium thiosulfate, inorganic initiators in which small amounts of iron, ferrous salts, silver sulfate, etc. coexist, or disuccinic acid peroxide, diglutar. Examples include dibasic acid peroxides such as acid peroxides, azobisisobutyramidine hydrochloride, and organic initiators such as azobisbutyronitrile.

The amount of the polymerization initiator used can be changed as appropriate depending on the type, emulsion polymerization conditions, etc., but it is usually 0.0005 to 0.00 per 100 parts by weight of monomers to be emulsion polymerized.
．． About 5 parts by weight is preferably employed.

[0043] These polymerization initiators may be added all at once, or may be added in portions if necessary.

[0044] Furthermore, for the purpose of increasing the pH of the emulsion,
A pH adjuster may also be used. Such pH adjusters include inorganic bases such as sodium carbonate, potassium carbonate, sodium hydrogen orthophosphate, sodium thiosulfate, and sodium tetraborate, and organic bases such as ammonia water triethylamine, triethanolamine, dimethylethanolamine, and diethylethanolamine. Examples include.

The amount of the pH adjuster added is usually about 0.05 to 2 parts by weight, preferably about 0.1 to 2 parts by weight, per 100 parts by weight of the emulsion polymerization medium. The higher the pH, the faster the polymerization rate tends to be.

[0046] The emulsion polymerization initiation temperature is appropriately selected depending on the type of polymerization initiator, but usually,
A temperature of about 0 to 100°C, particularly about 10 to 90°C, is preferably employed. Further, the reaction pressure can be selected as appropriate, but is usually 1 to 100 kg/cm2, particularly 2 to 50 kg/cm2.
It is desirable to adopt approximately g/cm2.

In this production method, additives such as monomers, solvents, initiators, etc. may be added all at once and polymerized, but the particle size of the dispersed particles may be reduced to improve the stability of the dispersion and the gloss of the coating film. For the purpose of improving various physical properties such as, before adding the polymerization initiator, pre-emulsification may be performed using a stirrer such as a homogenizer, and then the initiator may be added to polymerize. Further, the monomers may be added in portions or continuously, and the monomer composition may be different in this case.

The aqueous dispersion of the present invention can be used as it is as an aqueous paint, but if necessary, it may be added with a colorant, a plasticizer, an ultraviolet absorber, a leveling agent, an anti-cissing agent, an anti-burr agent, and a curing agent. etc. may be mixed. Examples of the coloring agent include dyes, organic pigments, and inorganic pigments. Examples of the plasticizer include conventionally known ones, such as low molecular weight plasticizers such as dimethyl phthalate and dioctyl phthalate, and high molecular weight plasticizers such as vinyl polymer plasticizers and polyester plasticizers. Additionally, a pH adjuster may be added to improve the stability of the aqueous dispersion.

Examples of the curing agent include block isocyanates such as hexamethylene isocyanate trimer or emulsified dispersions thereof, melamine resins such as methylated melamine, methylolated melamine, butyrolated melamine, methylated urea, butylated urea, etc. Examples include urea resins, polyfunctional carboxylic acids, polyfunctional carbonyl group-containing compounds, polyfunctional aziridine compounds, dihydrazine compounds, metal salts, and EDTA chelate complexes/complex salts. These curing agents are selected depending on the reactive group contained in the fluorine-containing copolymer.

[0050] When the aqueous dispersion of the present invention is used as an aqueous paint base, it may be used as it is, but
It is better to use a blend of acrylic polymers or other aqueous dispersions with different compositions, such as the aqueous dispersions of the present invention, to improve the physical properties such as gloss, antifouling properties, hardness, and adhesion of the coating film, as well as pigment dispersibility. In some cases, it may improve performance or be advantageous in terms of cost. Further, when adding a pigment, it is preferable to add 5 phr or more.

[0051]

[Examples] The present invention will be specifically explained below with reference to synthesis examples and examples, but the present invention is not limited to these examples in any way. In addition, the parts in the following examples indicate parts by weight unless otherwise specified.

Example 1 23 parts of ethyl vinyl ether, 0.2 parts of n-butyl divinyl ether, and 4.5 parts of macromonomer A having a hydrophilic moiety were placed in a stainless steel autoclave (withstand pressure 50 kg/cm2) with an internal volume of 200 ml and equipped with a stirrer. , 99.1 parts of ion-exchanged water, 0.35 parts of ammonium perfluorooctanoate, 0.35 parts of potassium carbonate, 0.02 parts of sodium bisulfite, 0.11 parts of ammonium persulfate.
Cool with ice and add 3.5 kg of nitrogen gas.
After repeating this twice, degassing to 10 mmHg and removing dissolved air, 38.0 parts of chlorotrifluoroethylene was charged, and the reaction was carried out at 30°C for 12 hours. Ta.

[0053] To 100 parts of the obtained aqueous dispersion, 5 parts of film thickening agent (Texanol Cs-12) and 2 parts of film thickening agent (2 parts) were added.
-butoxyethanol) 10 parts, thickener (Revios CR
) and 0.6 parts of a leveling agent, and further 10 parts of a pigment dispersion (containing 23% by weight of titanium oxide) were added to prepare a coating composition.

Table 1 shows the results of stain removal tests conducted on this coating composition.

Example 2 In the autoclave, 19.5 parts of cyclohexyl vinyl ether, 12 parts of ethyl vinyl ether, 5.5 parts of macromonomer A having a hydrophilic site, 0.7 parts of divinyl ether, 114.6 parts of ion-exchanged water, 0.44 part of ammonium perfluorooctanoate, 0.44 part of potassium carbonate, 0.02 part of sodium bisulfite, and 0.14 part of ammonium persulfate were charged and treated in the same manner as in Example 1, followed by 30.0 parts of tetrafluoroethylene. After charging 9 parts, the reaction was carried out at 30°C for 12 hours.

The resulting aqueous dispersion was mixed with the same paint composition as in Example 1 and subjected to a stain removal test. Table 1 shows the results.

Example 3 In the autoclave, 21.7 parts of cyclohexyl vinyl ether, 10.6 parts of ethyl vinyl ether, and 6.4 parts of caprolactone-modified allyl vinyl ether carboxylic acid were added.
parts, 6.9 parts of macromonomer B having a hydrophilic site,
Ion exchange water 124.7 parts, ammonium perfluorooctanoate 0.44 parts, potassium carbonate 0.44 parts, dimethylethanolamine 2 parts, ammonium persulfate 0.
After charging 14 parts and treating in the same manner as in Example 1, 38.2 parts of chlorotrifluoroethylene was charged and 1
The reaction was carried out for 2 hours.

The resulting aqueous dispersion was mixed with the same paint composition as in Example 1 and subjected to a stain removal test. Table 1 shows the results.

Example 4 20.0 parts of ethyl vinyl ether and 1.5 parts of glycidyl vinyl ether were placed in a stainless steel autoclave with an internal volume of 200 ml (pressure resistance 50 kg/cm2) equipped with a stirrer.
4.5 parts of macromonomer A having a hydrophilic site, 2 parts of n-butyl vinyl ether, 2 parts of fluorinated allyl vinyl ether, 99.1 parts of ion-exchanged water, 0.35 parts of potassium carbonate, 0.3 parts of sodium bisulfite. Part 02,
Example 1: 0.11 parts of ammonium persulfate was charged.
After treatment in the same manner as above, chlorotrifluoroethylene was
8.7 parts were charged and the reaction was carried out at 30°C for 12 hours.

The resulting aqueous dispersion was mixed with the same paint composition as in Example 1 and subjected to a stain removal test. Table 1 shows the results.

Example 5 354 parts of ethyl vinyl ether, 24 parts of hydroxybutyl vinyl ether, 55 parts of macromonomer B having a hydrophilic moiety, and n-
Butylene divinyl ether 5 parts, ion exchange water 98
0 parts, ammonium perfluorooctanoate 10.4 parts, emulsifier manufactured by Nippon Nyukazai Co., Ltd. Newcol 293
13 parts of Newcol 240, 2.1 parts of ammonia water, and 0.7 parts of ammonium persulfate were added, cooled with ice, and 3.5 kg of nitrogen gas was added.
After repeating this process twice and degassing to 120 mmHg to remove dissolved air, 243 parts of chlorotrifluoroethylene was charged and the reaction was started at 30°C. The pressure in the autoclave at this time was 3 kg/cm2G, and as the reaction progressed, the pressure decreased, but an additional 365 parts of chlorotrifluoroethylene was added to keep the pressure constant (3 kg/cm2G). Thereafter, the reaction was carried out until the weight reached approximately 0 kg/cm2G.

The resulting aqueous dispersion was mixed with the same paint composition as in Example 1 and subjected to a stain removal test. Table 1 shows the results.

Example 6 354 parts of ethyl vinyl ether, 24 parts of hydroxybutyl vinyl ether, 55 parts of macromonomer A having a hydrophilic moiety, and 5 parts of vinyl acrylate were placed in a stainless steel autoclave with an internal volume of 2500 ml and equipped with a stirrer (pressure resistance 50 kg/cm2). 980 parts of ion-exchanged water, 10.4 parts of ammonium perfluorooctanoate, 13 parts of emulsifier Newcol 293 manufactured by Nippon Nyukazai Co., Ltd.
Similarly, 18 parts of Newcol 240, 2.1 parts of triethanolamine, and 0.7 parts of ammonium persulfate were charged, cooled with ice, and nitrogen gas was added at 3.5 kg/
After repeating this process twice and degassing to 120 mmHg to remove dissolved air, 243 parts of chlorotrifluoroethylene was charged and the reaction was started at 30°C. The pressure in the autoclave at this time was 3 kg/cm2G, and as the reaction progressed, the pressure decreased, but an additional 365 parts of chlorotrifluoroethylene was added to keep the pressure constant (3 kg/cm2G). Thereafter, the reaction was carried out until the weight reached approximately 0 kg/cm2G.

The resulting aqueous dispersion was mixed with the same paint composition as in Example 1 and subjected to a stain removal test. Table 1 shows the results.

Comparative Example 1 354 parts of ethyl vinyl ether, 24 parts of hydroxybutyl vinyl ether, 55 parts of macromonomer A having a hydrophilic moiety, and 980 parts of ion-exchanged water were placed in a stainless steel autoclave with an internal volume of 2500 ml and equipped with a stirrer (pressure resistance 50 kg/cm2). 10.4 parts of ammonium perfluorooctanoate, emulsifier manufactured by Nippon Nyukazai Co., Ltd. Newc
13 copies of ol 293, also Newcol 240
18 parts of potassium carbonate, 3.75 parts of potassium carbonate, and 0.7 parts of ammonium persulfate were added, cooled with ice, and 3.75 parts of nitrogen gas was added.
．． Pressurize and degas to 5 kg/cm2.
After repeating this process several times, it was degassed to 120 mmHg and dissolved air was removed.
The reaction is started at 30°C. The pressure in the autoclave at this time is 3 kg/cm2G, and as the reaction progresses, the pressure decreases, but the pressure remains constant (3 kg/cm2
G) Add an additional 365 parts of chlorotrifluoroethylene so that Thereafter, the reaction was carried out until the weight reached approximately 0 kg/cm2G.

The resulting aqueous dispersion was mixed with the same paint composition as in Example 1 and subjected to a stain removal test. Table 1 shows the results.

Stain Removal Test The coatings of Examples 1 to 6 and Comparative Example 1 were mixed with the curing agents shown in Table 1, and coated on an aluminum plate under the curing conditions shown in Table 1. Initial color difference was measured using a color difference meter. This coated board was exposed outdoors for one month in Kawasaki City. Thereafter, the color difference after washing with water was measured, and the ratio (recovery rate) to the initial color difference was calculated.

[0068]

[Table 1]

[0069] The macromonomer having a hydrophilic moiety used in the Examples and Comparative Examples is CH2=CHO(CH2)4(OCH2CH2)nOH
The macromonomer A having a hydrophilic site has a number average molecular weight of 700, and the macromonomer B having a hydrophilic site has a number average molecular weight of 500.

[0070]

[Effects of the Invention] The aqueous dispersion of the present invention has extremely excellent mechanical and chemical stability, and also has excellent film-forming properties. Furthermore, the coating film obtained using the aqueous dispersion of the present invention has the advantage of being excellent in weather resistance and stain removal properties.

Claims (7)

[Claims] Claim 1: Essential constituents include polymerized units based on fluoroolefins, polymerized units based on macromonomers having hydrophilic sites, and polymerized units based on monomers having two or more polymerizable functional groups. An aqueous dispersion in which a fluorine-containing copolymer is dispersed in water. 2. In claim 1, the fluorine-containing copolymer contains 20 to 80 mol% of polymerized units based on fluoroolefins and 0.1 to 25 mol% of polymerized units based on macromonomers having a hydrophilic site. , 0.01 to 20 polymerized units based on monomers having two or more polymerizable functional groups.
An aqueous dispersion that is a copolymer containing mol%. 3. The aqueous dispersion according to claim 1, wherein the macromonomer having a hydrophilic site is a polyether having a radically polymerizable unsaturated group at one end. 4. The aqueous dispersion according to claim 1, wherein the macromonomer having a hydrophilic site is polyoxyethylene having a radically polymerizable unsaturated group at one end. 5. In claim 1, the fluorine-containing copolymer is
An aqueous dispersion that is a copolymer comprising polymerized units containing reactive groups selected from hydroxyl groups, epoxy groups, carboxylic acid groups, carbonyl groups, and hydrazine residues. 6. In claim 1, the fluorine-containing copolymer is
An aqueous dispersion which is a copolymer containing a polymerized unit containing a reactive group selected from a hydroxyl group, an epoxy group, a carboxylic acid group, a carbonyl group, and a hydrazine residue in a proportion of 0 to 30 mol%. 7. The aqueous dispersion according to claim 1, which contains at least two types of fluorine-containing copolymers having different polymerization compositions.