JPH07258499A - Aqueous dispersion of fluorine-containing polymer - Google Patents

Abstract

PURPOSE:To provide an aqueous dispersion of a fluorine-containing polymer, more particularly an aqueous dispersion of a fluorine-containing polymer having excellent precipitation stability and capable of easily forming a coating film especially having excellent weather resistance and stain-proofness. CONSTITUTION:This aqueous dispersion of a fluorine-containing popymer is produced by polymerizing 50-80wt.% of vinylidene fluoride, 20-50wt.% of hexafluoropropylene and 0-30wt.% of other copolymerizable monomer and dispersing the obtained fluorine-containing polymer particles having an average particle diameter of 30-200nm in an aqueous medium. As an alternative, this aqueous dispersion is produced by preparing composite polymer particles by compounding a fluorine-containing polymer obtained by the polymerization of 50-80wt.% of vinylidene fluoride, 20-50wt.% of hexafluoropropylene and 0-30wt.% of other copolymerizable monomer with an acrylic polymer obtained by the polymerization of 40-100wt.% of an alkyl (meth)acrylate and 0-60wt.% of other copolymerizable monomer and dispersing the obtained composite polymer particles in an aqueous medium.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous dispersion of a fluoropolymer, more specifically, a fluorine-containing polymer having excellent sedimentation stability by which a coating film having excellent weather resistance and stain resistance can be easily formed. It relates to an aqueous polymer dispersion.

[0002]

Fluorine-containing polymer aqueous dispersions have excellent weather resistance and do not need to be reapplied for a long period of time.
Excellent in gas impermeability and electrical insulation,
It is not necessary to use a large amount of solvent like the solvent-type solvent-based fluororesin that has been generally used until now, and development has been advanced in recent years as it meets social demands such as environmental protection, resource saving, and safety. Has been. However, the fluoropolymer aqueous dispersion, compared to solvent-based fluororesin,
It is inferior in film forming property and storage stability. That is, in the fluoropolymer aqueous dispersion, the fluoropolymer particles having a small intermolecular force between the polymers and high specific gravity are dispersed in the aqueous medium. Is not sufficiently fused to form a film, and the difference in specific gravity from the aqueous medium is large, so that sedimentation is likely to occur. On the other hand, the solvent-based fluororesin is in the form of a solution and does not have a particle morphology, the intermolecular force between the polymers is maximized by the solvent volatilization at the time of drying, and the polymer is sufficiently in the solution state. It does not settle out. In order to eliminate the drawbacks of such an aqueous fluoropolymer dispersion, conventionally, a water-soluble additive is added, the monomer composition is optimized, a core / shell structure is introduced into the fluoropolymer particles, an aqueous solution is used. Although various improvements such as addition of an organic solvent have been attempted, the actual situation is that sufficient results have not been obtained yet.

[0003]

Therefore, an object of the present invention is to provide a fluoropolymer aqueous dispersion which easily forms a coating film excellent in weather resistance and stain resistance and has excellent sedimentation stability. is there.

[0004]

Means for Solving the Problems That is, the present invention provides (1)
Vinylidene fluoride 50 to 80% by weight, propylene hexafluoride 20 to 50% by weight and other copolymerizable monomers 0
To 30% by weight of a monomer to be polymerized, and the average particle diameter of the fluoropolymer particles is 30 to 200 nm (hereinafter,
"Fluorine-containing polymer") is dispersed in an aqueous medium, a fluoropolymer aqueous dispersion (hereinafter,
"Dispersion A") and (2) vinylidene fluoride 50-
Fluorine-containing polymer obtained by polymerizing a monomer composed of 80% by weight, 20 to 50% by weight of propylene hexafluoride and 0 to 30% by weight of other copolymerizable monomer, and (meth) acrylic acid alkyl ester 40. To 100 wt% and other copolymerizable monomer 0 to 60 wt% are polymerized to form an acrylic polymer (hereinafter referred to as "acrylic polymer"). A fluoropolymer aqueous dispersion (hereinafter, referred to as "dispersion B"), characterized in that polymer particles are dispersed in an aqueous medium.

The fluoropolymer in the present invention contains vinylidene fluoride in an amount of 50 to 80% by weight, preferably 60 to 80%.
%, Particularly preferably 60 to 70% by weight, propylene hexafluoride 20 to 50% by weight, preferably 20 to 40% by weight, particularly preferably 30 to 40% by weight, and other copolymerizable monomers 0 to It is obtained by copolymerizing 30% by weight, preferably 0 to 20% by weight, particularly preferably 0 to 10% by weight, of a monomer. In the present invention, when the vinylidene fluoride content is less than 50% by weight, the stain resistance is inferior.
If it exceeds 5% by weight, the film-forming property is poor. When the content of propylene hexafluoride is less than 20% by weight, the film-forming property is inferior.
If it exceeds 5% by weight, the stain resistance is poor. If the amount of the other copolymerizable monomer is more than 30% by weight, the stain resistance is poor.

The above-mentioned other copolymerizable monomers include
For example, vinyl fluoride, tetrafluoroethylene, trifluorochloroethylene, hexafluoroisobutylene,
Perfluoroacrylic acid or its alkyl ester,
Fluorine-containing ethylenically unsaturated compounds such as perfluoromethacrylic acid or its alkyl esters, fluoroalkyl esters of acrylic acid or methacrylic acid, perfluorovinyl ether, perfluoroalkyl vinyl ether, etc., fluorine-free ethylenic compounds such as cyclohexyl vinyl ether, hydroxyethyl vinyl ether, etc. Examples thereof include unsaturated compounds, fluorine-free diene compounds such as butadiene, isoprene, and chloroprene. Among these, vinyl fluoride, tetrafluoroethylene, trifluorochloroethylene, hexafluoroisobutylene, and perfluorovinyl ether are preferably used.

In producing the above-mentioned fluoropolymer, various methods such as emulsion polymerization, solution polymerization and precipitation polymerization can be adopted. In the present invention, however, the fluorine-containing polymer obtained by emulsion polymerization is particularly preferable. Coalescence is preferred. The above-mentioned fluoropolymer must be dispersed as particles in an aqueous medium, but the dispersing method is not particularly limited. In the present invention, examples of the aqueous medium include water and hydrophilic solvents such as alcohol and ether that do not dissolve the fluoropolymer, but it is preferable to use water. As a method of dispersing the fluoropolymer in an aqueous medium, for example, (i) a method of emulsion polymerizing the constituent monomers in an aqueous medium, (ii) a method of phase inversion of the fluoropolymer solution into an aqueous dispersion, (iii) A method in which the constituent monomers are precipitated and polymerized and then the resulting polymer particles are dispersed in an aqueous medium can be mentioned. Of these methods,
The emulsion polymerization method is a preferred method since the aqueous dispersion of the fluoropolymer particles can be used as it is for emulsion polymerization. Emulsion polymerization of a fluoropolymer is carried out by using a raw material monomer in an aqueous medium as an emulsifier, a polymerization initiator, a p
It can be carried out by polymerizing in the presence of an H regulator and the like.

As the emulsifier, an anionic surfactant,
A nonionic surfactant, a combination of an anionic surfactant and a nonionic surfactant, and the like are used, and an amphoteric surfactant and a cationic surfactant can also be used depending on the case. Examples of the anionic surfactant include higher alcohol sulfuric acid ester sodium salt, alkylbenzene sulfonic acid sodium salt, succinic acid dialkyl ester sulfonic acid sodium salt, alkyldiphenyl ether disulfonic acid sodium salt, polyoxyethylene alkyl ether sulfuric acid sodium salt, polyoxy Examples thereof include ethylene alkyl phenyl ether sulfate sodium salt. Of these, lauryl sulfate sodium salt, dodecylbenzenesulfonic acid sodium salt,
Polyoxyethylene alkyl ether sulfate sodium salt, polyoxyethylene alkylphenyl ether sulfate sodium salt and the like are preferable. Examples of the nonionic surfactant include polyoxyethylene alkyl ether, polyoxyethylene alkylaryl ether, polyoxyethylene fatty acid ester, and polyoxyethylene sorbitan fatty acid ester. Generally, polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether and the like are used. Examples of the amphoteric surfactant include lauryl betaine, hydroxyethyl imidazoline sulfate sodium salt, and imidazoline sulfonic acid sodium salt. Examples of the cationic surfactant include alkylpyridinium chloride, alkyltrimethylammonium chloride, dialkyldimethylammonium chloride, alkyldimethylbenzylammonium chloride and the like. Further, in the present invention, a fluorosurfactant such as perfluoroalkylcarboxylic acid salt, perfluoroalkylsulfonic acid salt, perfluoroalkylphosphoric acid ester, perfluoroalkylpolyoxyethylene, perfluoroalkylbetaine is used as an emulsifier. You can also do it. In the present invention, a surfactant having a fluoroalkyl group is preferably used, but a surfactant having a perfluoroalkyl group having 9 or more carbon atoms is particularly preferable. Further, perfluorocarboxylic acids having 9 or more carbon atoms and salts thereof are preferable, and perfluorononanoic acid, perfluorodecanoic acid and salts thereof are particularly preferable. Among the perfluorocarboxylic acids and their salts, ammonium salts of perfluorocarboxylic acids are preferred. The amount of the emulsifier used is usually about 0.05 to 5 parts by weight per 100 parts by weight of all the monomers.

As the polymerization initiator, a water-soluble polymerization initiator such as potassium persulfate, ammonium persulfate, hydrogen peroxide, or a redox system in which these water-soluble polymerization initiator and a reducing agent are combined can be used. . Examples of the reducing agent include sodium pyrobisulfite, sodium hydrogen sulfite, sodium sulfite, sodium thiosulfate, L-ascorbic acid or a salt thereof, sodium formaldehyde sulfoxylate, ferrous sulfate and glucose. An oil-soluble polymerization initiator can also be used by dissolving it in a solvent. Examples of the oil-soluble polymerization initiator include 2,2'-azobisisobutyronitrile and 2,2'-azobis- (4-methoxy-).
2,4-dimethylvaleronitrile), 2,2'-azobis-2,4-dimethylvaleronitrile, 1,1'-azobiscyclohexane-1-carbonitrile, 2,2'-
Asobisisovaleronitrile, 2,2'-azobisisocapronitrile, 2,2'-azobis (phenylisobutyronitrile), benzoyl peroxide, di-t-butyl peroxide, dilauroyl peroxide, cumene Hydroperoxide, diisopropylbenzene hydroperoxide, paramenthane hydroperoxide,
Examples thereof include t-butyl hydroperoxide, 3,5,5-trimethylhexanol peroxide, diisopropyl peroxydicarbonate and t-butyl peroxy (2-ethylhexanoate). Preferred oil-soluble polymerization initiators are 2,2'-azobisisobutyronitrile, benzoyl peroxide, di-t-butyl peroxide, diisopropyl peroxydicarbonate and the like. The amount of the polymerization initiator used is usually about 0.1 to 5 parts by weight per 100 parts by weight of all the monomers. An oil-soluble polymerization initiator is preferably used from the viewpoint of weather resistance. When a water-soluble initiator is used, it is preferably used in an amount of 1 part by weight or less per 100 parts by weight of all monomers from the viewpoint of weather resistance.

As the chain transfer agent, halogenated hydrocarbons (eg, chloroform, bromoform, etc.), mercaptans (eg, n-dodecyl mercaptan, t-dodecyl mercaptan, n-octyl mercaptan, n-hexadecyl mercaptan, etc.), Xanthogens (eg, dimethylxanthogen disulfide, diethylxanthogen disulfide, diisopropylxanthogen disulfide, etc.), terpenes (eg, dipentene, terpinolene, etc.), thiuram sulfides (eg, tetremethylthiuram monosulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, dipenta). (Methyl thiuram disulfide, etc.), isopentane, and alcohols. In particular, isopentane, methanol, ethanol and isopropanol are preferable. The amount of the chain transfer agent used is about 0 to 10 parts by weight based on 100 parts by weight of all the monomers. Examples of the chelating agent include glycine, alanine, ethylenediaminetetraacetic acid and the like, and examples of the pH adjusting agent include sodium carbonate, potassium carbonate, sodium hydrogen carbonate, sodium diphosphate and the like. Chelating agent and p
The amount of H adjuster used is about 0 to 0.1 parts by weight and 0 to 3 parts by weight, respectively, per 100 parts by weight of all the monomers. In the present invention, the polystyrene-converted weight average molecular weight of the fluoropolymer is usually 1 to 500,000.

The average particle size of the fluoropolymer particles in the present invention is 30 to 200 nm, preferably 30 to 15
The range is 0 nm, particularly preferably 30 to 100 nm. If the average particle size is smaller than 30 nm, a large amount of a surfactant that adversely affects the weather resistance must be used in order to maintain the dispersion stability of the particles. If it is larger than 200 nm, the sedimentation stability and the film-forming property are deteriorated. Inferior. In the present invention, in order to make the average particle diameter of the fluoropolymer particles within a specific range, the emulsifier is usually 0.2 part by weight or more, preferably 9 or more carbon atoms, based on 100 parts by weight of all the monomers. The amount of the perfluorocarboxylic acid or salt thereof is 0.2 part by weight or more. The solid content of the dispersion A of the present invention is usually 10 to 7.
It is 0% by weight, preferably 20 to 60% by reception. Dispersion A can be used alone or in combination of two or more. In the present invention, the fluorine-containing polymer contains 40 to 100% by weight of (meth) acrylic acid alkyl ester.
By using the composite polymer particles that are composited with the acrylic polymer contained, stain resistance, film-forming property, sedimentation stability,
It is possible to obtain a more excellent fluoropolymer aqueous dispersion. In the present invention, the composite polymer particles are particles in which two or more polymers are present in one particle regardless of the presence or absence of a chemical bond between the polymers. Examples of the particle structure of the composite polymer particles include a core / shell type in which any one of the polymers covers the surface of the particles and a homogeneous type in which all the polymers are compatible. In the present invention, any particle structure is acceptable, but a homogeneous type is preferred in order to reduce restrictions on use conditions, particularly drying temperature and drying time.

In the present invention, as the method for producing the composite polymer particles, polymer particles of either fluorine-containing polymer particles or acrylic polymer particles are prepared in advance, and one of the polymer particles is present. A method for polymerizing the other polymer below, a method for polymerizing a monomer for obtaining a fluoropolymer and a monomer for obtaining an acrylic polymer in the same reaction vessel, containing a fluoropolymer The method of converting the resulting solution into an aqueous dispersion can be mentioned. In the present invention, a method of polymerizing a monomer containing a (meth) acrylic acid alkyl ester in the presence of fluoropolymer particles is preferable. In the present invention, the (meth) acrylic acid alkyl ester is 40 to 100% by weight, preferably 40 to 100% by weight in the acrylic polymer.
99.9% by weight, particularly preferably 50 to 99% by weight. 40% by weight of (meth) acrylic acid alkyl ester
If it is less, the weather resistance is poor.

In the present invention, examples of the (meth) acrylic acid alkyl ester that can be used for producing the composite polymer particles include methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate and acrylic acid. Isobutyl, n-amyl acrylate, isoamyl acrylate, hexyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, etc., preferably butyl acrylate, acrylic acid esters such as 2-ethylhexyl acrylate, methacrylic acid Methyl, ethyl methacrylate, methacrylic acid alkyl ester, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n methacrylate
-Amyl, isoamyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, 2-methacrylic acid
Methacrylic acid esters such as ethylhexyl and lauryl methacrylate can be mentioned. In the present invention, it is preferable to use a methacrylic acid alkyl ester having an alkyl group having 1 or 2 carbon atoms, that is, methyl methacrylate or ethyl methacrylate, from the viewpoint of weather resistance.
Further, from the viewpoint of film forming property, it is preferable to use a combination of methacrylic acid alkyl ester and acrylic acid alkyl ester. The acrylic acid alkyl ester is
It is usually preferable to use the acrylic polymer in an amount of 5 to 50% by weight. In the present invention, examples of the monomer that can be copolymerized with the (meth) acrylic acid ester include the following. (A) A monomer having a plurality of oxyethylene units as repeating units, for example, methoxypolyethylene glycol acrylate, methoxydiethylene glycol acrylate, ethoxydiethylene glycol acrylate, methoxytriethylene glycol acrylate, ethoxytriethylene glycol acrylate, phenoxypolyethylene glycol acrylate, methoxypolyethylene glycol Acrylate, nonylphenoxy polypropylene glycol acrylate, methoxy polyethylene glycol methacrylate, methoxytriethylene glycol methacrylate, phenoxy polyethylene glycol methacrylate, methoxy polyethylene glycol methacrylate, nonylphenoxy polypropylene glycol methacrylate Nonyl-1-propenylphenoxy polyethylene glycol, nonyl-1-propenylphenoxy polyethylene glycol sulfate salt, octyl-1-propenylphenoxy polyethylene glycol, octyl-1-propenylphenoxy polyethylene glycol sulfate salt, 2- (nonylphenoxy) -1- (allyloxymethyl) ethoxy polyethylene glycol, 2- (nonylphenoxy) -1- (allyloxymethyl) ethoxy polyethylene glycol sulfate salt and the like. From the viewpoint of sedimentation stability, it is preferably used in the range of 0.1 to 5% by weight.

(B) Ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, fumaric acid,
Maleic acid, maleic anhydride, crotonic acid, etc. In particular, acrylic acid and itaconic acid are preferably used, and it is preferably used in the range of 0.1 to 5% by weight from the viewpoint of sedimentation stability. (C) Other monomers such as acrylamide, methacrylamide, N-methylacrylamide, N-methylmethacrylamide, N-methylolacrylamide, N-
Amyl compounds such as methylol methacrylamide, N-alkyl acrylamide, N-alkyl methacrylamide, N, N-dialkyl acrylamide, N, N-dialkyl methacrylamide, diacetone acrylamide, diacetone methacrylamide, 2-hydroxyethyl acrylate, N, N-dialkylaminoethyl acrylate,
Glycidyl acrylate, fluoroalkyl acrylate,
Acrylic esters such as acetonitrile acrylate and diacetone acrylate, 2-hydroxyethyl methacrylate, N, N-dialkylaminoethyl methacrylate, glycidyl methacrylate, fluoroalkyl methacrylate, methacrylic acid such as ethylene glycol dimethacrylate and diacetone methacrylate. Ester, acrolein, vinyl ether compounds such as allyl glycidyl ether, conjugated dienes such as 1,3-butadiene, isoprene and chloroprene, aromatic vinyl compounds such as styrene, α-methylstyrene, halogenated styrene, divinylbenzene and formyl styrene, acrylonitrile , Vinyl cyanide compounds such as methacrylonitrile, vinyl alkyl ketones such as vinyl methyl ketone, vinyl ethyl ketone and vinyl isobutyl ketone. Ketone.

Among these other copolymerizable monomers, particularly 0.1-5% by weight of ethylenically unsaturated carboxylic acid can improve the sedimentation stability of the resulting composite polymer particles. it can. The acrylic polymer 100
The ratio of the fluoropolymer with respect to parts by weight is 10 to 100.
The amount is 00 parts by weight, preferably 50 to 5000 parts by weight, more preferably 100 to 1000 parts by weight. When the amount of the fluoropolymer is more than 10,000 parts by weight, the effect of improving stain resistance, film-forming property and sedimentation stability is small, and when it is less than 10 parts by weight, the weather resistance is poor.

In the present invention, emulsion polymerization of an acrylic polymer in the presence of fluoropolymer particles can be considered as one kind of seed polymerization. Although the reaction behavior is not always clear, it is considered that the added monomer is absorbed or adsorbed mainly in the fluoropolymer particles and the polymerization proceeds while swelling the particles. The conditions of this emulsion polymerization are not particularly limited, and for example, in the presence of an emulsifier and a polymerization initiator in an aqueous medium, if necessary, a chain transfer agent, a chelating agent, a pH adjusting agent, an organic solvent, etc. are added. 1-30 at a temperature of about 30-100 ° C
React for about an hour. As the emulsifier, an anionic surfactant, a nonionic surfactant, a combination of an anionic surfactant and a nonionic surfactant, and the like are used. In some cases, an amphoteric surfactant, a cationic surfactant. Surfactants can also be used, and specific examples of each are the same as those used for producing the fluoropolymer. Further, in the present invention, a so-called reactive emulsifier which is copolymerizable with an acrylic polymer, such as sodium styrenesulfonate and sodium allylalkylsulfonate, can be used. The amount of emulsifier used is usually about 0.05 to 5 parts by weight per 100 parts by weight of the acrylic polymer.

As the polymerization initiator, chain transfer agent and chelating agent, the same ones as used in the production of the fluoropolymer can be used. Preferred polymerization initiators are 2,2'-azobisisobutyronitrile, benzoyl peroxide,
Cumene hydroperoxide, diisopropylbenzene hydroperoxide, paramenthane hydroperoxide, t-butyl hydroperoxide, 3,5,5-
Examples thereof include oil-soluble initiators such as trimethylhexanol peroxide and t-butylperoxy (2-ethylhexanoate). The amount of the polymerization initiator used is usually about 0.1 to 3 parts by weight per 100 parts by weight of the acrylic polymer. The amount of the chain transfer agent used is about 0 to 10 parts by weight per 100 parts by weight of the acrylic polymer. The amounts of the chelating agent and the pH adjusting agent used are 0 to 0.1 parts by weight and 0 to 3 parts by weight, respectively, per 100 parts by weight of the acrylic polymer. As the organic solvent,
For example, methyl ethyl ketone, acetone, trichlorotrifluoroethane, methyl isobutyl ketone, dimethyl sulfoxide, toluene, dibutyl phthalate, methyl pyrrolidone, ethyl acetate and the like can be mentioned. The amount of the solvent used is preferably a small amount within the range that does not impair workability, disaster prevention safety, environmental safety and manufacturing safety, and is about 20 parts by weight or less per 100 parts by weight of the acrylic polymer.

When the acrylic polymer is emulsion-polymerized in the presence of the fluoropolymer particles, the fluoropolymer particles and the acrylic monomer can be added by various methods.
As a method of adding them, a method of collectively adding the entire amount of the acrylic monomer to the aqueous dispersion of the fluoropolymer particles, a part of the acrylic monomer to the aqueous dispersion of the fluoropolymer particles is added. After charging and reacting, a method of charging the remaining monomer continuously or in a divided manner, a method of continuously or dividedly adding the total amount of the acrylic monomer to the aqueous dispersion of fluoropolymer particles, an acrylic Under the polymerization of monomer,
Examples thereof include a method of continuously or dividingly adding the fluoropolymer particles. A preferable addition method is a method in which the amount of a part of the monomers initially charged in the above-mentioned method is 50% by weight or more of the total amount of the monomers. The average particle size of the composite polymer particles is usually in the range of 30 to 200 nm. It is preferably in the range of 30 to 150 nm, particularly preferably in the range of 30 to 100 nm. If the average particle size is smaller than 30 nm, a large amount of a surfactant that adversely affects the weather resistance must be used in order to maintain the dispersion stability of the particles. If it is larger than 200 nm, the sedimentation stability and the film-forming property are deteriorated. Inferior. The average particle size of the composite polymer particles, by appropriately selecting the size of the fluoropolymer particles,
It can be adjusted. In the present invention, the solid content concentration of the dispersion B is usually 20 to 80% by weight, preferably 30.
Is about 70% by weight. Dispersion B may be used alone or in combination of two or more. Further, the fluoropolymer aqueous dispersion and the composite polymer particle aqueous dispersion may be mixed and used.

In the aqueous dispersion of the present invention, if necessary,
100% of various organic additives in terms of solid content of the aqueous dispersion.
40 parts by weight or less can be blended with respect to parts by weight. Examples of the additive include a silicone-based defoaming agent,
Antifreeze agents such as ethylene glycol and propylene glycol, dyes, organic pigments, dispersants, pH adjusting agents such as ethanolamine, hydroxyethyl cellulose, polyether urethane, thickeners such as acrylic acid copolymers, butyl cellosolve, ethyl Examples thereof include wettability improvers such as cellosolve, organic fillers, preservatives, antifungal agents, water resistance agents, antiaging agents, ultraviolet absorbers, water-soluble solvents, and film-forming aids. As the film-forming aid, an aliphatic ester, a condensed derivative of ethylene glycol or propylene glycol, a ketone solvent, or the like is used, but a dimer or trimer etherified product of ethylene glycol or propylene glycol is preferable. At that time, a methyl ether compound is preferable, and a dimethyl ether compound is particularly preferable. Also,
Among the aliphatic esters, isobutyrate and monoisobutyrate of aliphatic diol can be preferably used.
If necessary, inorganic compounds such as pigments such as titanium oxide and iron oxide, fillers such as calcium carbonate and aerosil, and the like can be added to the aqueous dispersion of the present invention.

The aqueous dispersion of the present invention is particularly useful as a protective coating material for various substrates. In that case, it is dried at a temperature of usually room temperature to about 200 ° C. after being applied to the substrate. Uses include dry coatings for on-site construction, line coatings for ceramic building materials and metal products, clears for concrete exposure, various coatings such as anticorrosion coatings, anticorrosion coatings, water and oil repellents, release agents, release agents. , Lubricant, waterproof agent,
Examples thereof include stain inhibitors, weather resistance imparting agents, fiber treatment agents, paper processing agents, floor polishes, roof waterproofing agents, floor coating agents, and electrodeposition coating agents. In particular, an aqueous dispersion of composite polymer particles is excellent for various paints.

[0025]

The present invention will be described in more detail with reference to the following examples and comparative examples, but the present invention is not limited to these examples. Here, parts and percentages are by weight. Example 1 An autoclave with an internal volume of about 6 liters equipped with an electromagnetic stirrer was sufficiently replaced with nitrogen gas, then deoxidized pure water of 2.5 liters and ammonium perfluorodecanoate 25 g as an emulsifier were charged and stirred at 350 rpm. Meanwhile, the temperature was raised to 60 ° C. Then, a mixed gas composed of 44.2% by weight of vinylidene fluoride monomer (VdF) and 55.8% by weight of propylene hexafluoride monomer (HFP) was used for 20 k.
After charging until g / cm ² G, 25 g of a Freon 113 solution containing 20% by weight of a polymerization initiator, diisopropyl peroxydicarbonate, was introduced under pressure by nitrogen gas to initiate polymerization. Since the pressure drops as the polymerization progresses, VdF6
A mixed gas consisting of 0.2% by weight and 39.8% by weight of HFP was successively injected to maintain the pressure at 20 kg / cm ² G to continue the reaction. Since the polymerization rate decreases with the reaction time, after the lapse of 3 hours, the same amount of the polymerization initiator as described above was injected with nitrogen gas again, and the reaction was continued for another 3 hours. Then, the system was cooled and the stirring was stopped, and then the unreacted monomer was released to stop the reaction. The solid content concentration of the thus-obtained fluoropolymer aqueous dispersion was 30.5% by weight, and PHOTON CORRELATOR LPA-30 manufactured by Otsuka Electronics Co., Ltd.
The average particle size measured by 00S was 51 nm. The weight composition ratio of each monomer determined from ¹⁹ F-NMR is V
It was dF / HFP = 60/40. The film-forming property is measured with a minimum film-forming temperature measuring device manufactured by Rigaku Kogyo Co., Ltd. by rubbing the coating film with a finger and measuring the temperature at which the coating film does not come off as eraser dregs, as the minimum film-forming temperature. The sample was placed in a glass tube having a length of 1 m and allowed to stand for 1 month. The depth of the supernatant was evaluated. It is shown that the smaller the value of any of the characteristics, the better. The results are summarized in Table 1.

Examples 2 to 4 and Comparative Example 1 A fluoropolymer aqueous dispersion was obtained in the same manner as in Example 1 except that the amount of emulsifier was changed as shown in Table 1. The results are shown in Table 1.
Shown in.

[0027]

Comparative Example 2 In the same manner as in Example 1, 62% by weight of vinylidene fluoride,
A fluoropolymer dispersion liquid having an average particle diameter of 79 nm of 15% by weight of propylene hexafluoride and 23% by weight of tetrafluoroethylene was obtained. Minimum film formation temperature is 98 ° C, sedimentation depth is 3mm
Met. From the above data, it was found that the fluoropolymer aqueous dispersion of the invention is excellent in film-forming property and sedimentation stability. Examples 5 to 11 After purging the inside of a separable flask having a volume of 7 liters with nitrogen, 150 parts by weight of the fluoropolymer aqueous dispersion obtained in Example 1 and 2- (1-allyl)-
4-Nonylphenoxy polyethylene glycol ammonium sulfate (3 parts) was added and the temperature was raised to 75 ° C. Next, the monomer mixture shown in Table 2 (and optionally water) was added, and the mixture was stirred at 75 ° C for 30 minutes. After 0.5 part of sodium persulfate was added thereto and polymerization was carried out at 85 to 95 ° C. for 2 hours, the reaction was stopped by cooling to obtain an aqueous dispersion of composite polymer particles. In the same manner as in Example 1, the film forming property and the sedimentation stability were evaluated. Also, an iron plate degreased with xylene and an alkaline detergent (JIS-3141, SPCC
Plate, 0.8 × 70 × 150 mm) with an applicator having a gap of 150 μm, and dried at room temperature for 2 weeks,
Using a sunshine carbon arc type weather resistance tester,
The test was performed according to JIS-K5400, 9 / 8-1. The ratio (%) of the gloss of the sample after irradiation for 3000 hours to the gloss before irradiation was determined and evaluated according to the following criteria. ○: 100 to 80% △: 79 to 40% ×: 39% or less The coated plate obtained in the same manner was held in the Yokkaichi Plant of Japan Synthetic Rubber Co., Ltd. in the southwest direction at an angle of 45 ° from the horizontal plane.
The brightness difference (ΔL ^* ) after 1 month outdoor exposure was measured, and the stain resistance was evaluated according to the following criteria. ◯: 5 or less Δ: 5 to 10 ×: 10 or more The evaluation results are shown in Table 2.

[0029]

Example 12 and Comparative Example 3 Instead of the fluoropolymer aqueous dispersion of Example 1, the fluoropolymer aqueous dispersions of Comparative Example 1 (Example 12) and Comparative Example 2 (Comparative Example 3) were used. Was used in the same manner as in Example 5 to obtain an aqueous dispersion of composite polymer particles. Table 3 shows the evaluation results of the aqueous dispersions of these composite polymer particles and the fluoropolymer aqueous dispersions of Example 1 and Comparative Example 1 in the same manner as in Example 5.

[0031]

Example 13 50 parts of titanium oxide as a filler and 100 parts of polycarboxylic acid sodium salt as a dispersant (trade name: SN-DISPERSANT5) were added to 100 parts (in terms of solid content) of the aqueous dispersion of Example 5.
044, made by San Nopco) 2 parts, ethylene glycol 1 part as an antifreezing agent, preservative (product name SN-215, made by San Nopco) 0.05 part, defoamer (product name FOAMAST
0.5 parts of ER-AP, manufactured by San Nopco) and 5 parts of triethylene glycol dimethyl ether were added and adjusted with water to a solid content of 60% by weight, and then the viscosity was adjusted to 4000 using hydroxyethyl cellulose as a thickener.
Adjusted to cps. Mixing of these respective components was performed using a disper stirrer, and after sufficiently mixing, the mixture was transferred to a vacuum defoaming machine and defoamed to prepare a paint. An iron plate (JIS-3141, SPCC plate, 0.8 × 70 × 15) obtained by degreasing each of the obtained coating materials with xylene and an alkaline detergent.
(0 mm) with an airless spray gun so that the thickness of the coating film after drying will be 50 μm, and then 2
Dried for a week. The appearance of the coating film after drying is smooth and good.
The reflective gloss was 70.

Example 14 A coating composition was prepared in the same manner as in Example 13 except that the fluoropolymer aqueous dispersion obtained in Example 1 was used. When coated in the same manner as in Example 12, the coating film had irregularities with a size of 1 to 2 mm, the appearance was inferior, and the 60 ° reflective gloss was 35.

[0034]

As described above in detail, the coating film formed from the aqueous dispersion of the present invention has weather resistance, stain resistance, film-forming property,
Excellent sedimentation stability. Therefore, the aqueous dispersion of the present invention is useful as a coating agent for various materials including those for electrodeposition coating, as well as a fiber treatment agent, a paper processing agent, a floor coating agent and the like.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nobuyuki Ito 2-11-24 Tsukiji, Chuo-ku, Tokyo Japan Synthetic Rubber Co., Ltd.

Claims (3)

[Claims] 1. An average particle obtained by polymerizing a monomer comprising vinylidene fluoride 50 to 80% by weight, propylene hexafluoride 20 to 50% by weight and other copolymerizable monomer 0 to 30% by weight. A fluoropolymer aqueous dispersion, wherein the fluoropolymer particles having a diameter of 30 to 200 nm are dispersed in an aqueous medium. 2. A fluorine-containing polymer obtained by polymerizing 50 to 80% by weight of vinylidene fluoride, 20 to 50% by weight of propylene hexafluoride, and 0 to 30% by weight of another copolymerizable monomer. A composite polymer composed of a polymer and an acrylic polymer obtained by polymerizing a monomer composed of 40 to 100% by weight of (meth) acrylic acid alkyl ester and 0 to 60% by weight of another copolymerizable monomer. A fluoropolymer aqueous dispersion characterized in that coalesced particles are dispersed in an aqueous medium. 3. A fluorine-containing polymer obtained by polymerizing a monomer comprising 50 to 80% by weight of vinylidene fluoride, 20 to 50% by weight of propylene hexafluoride, and 0 to 30% by weight of another copolymerizable monomer. Composite polymer particles obtained by polymerizing a monomer consisting of 40 to 100% by weight of (meth) acrylic acid alkyl ester and 0 to 60% by weight of another copolymerizable monomer in the presence of coalesced in an aqueous medium. An aqueous dispersion of a fluoropolymer, which is dispersed.