JP2000128935A - Aqueous dispersion of fluorine-based copolymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an aqueous dispersion excellent in stability, film-forming properties, or the like, by dispersing a fluorine-based copolymer containing polymerization units based on a fluoroolefin, propylene, ethylene, or the like, and having a specific glass transition temperature in water. SOLUTION: This aqueous dispersion is obtained by dispersing a fluorine- based copolymer having -20 to +80 deg.C glass transition temperature and containing (A) a polymerization unit based on a fluoroolefin (e.g. tetrafluoroethylene), (B) a polymerization unit based on propylene, (C) a polymerization unit based on ethylene and/or (D) a polymerization unit based on butylene (e.g. isobutylene) in water. In the above copolymer, the amounts of the components are preferably 20-80 mol% of the component A, 2-70 mol% of the component B and 5-70 mol% of the components C and/or D. Furthermore, (E) a polymerization unit based on a monomer selected from a vinyl ester, a vinyl ether, isopropenyl ether and allyl ether is contained to improve the pigment dispersibility, adhesion, or the like, to substrates.

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 fluorocopolymer.

[0002]

2. Description of the Related Art Conventionally, vinylidene fluoride resins have been widely used as baking type paints because they have good weather resistance, heat resistance and chemical resistance and are soluble in solvents at high temperatures. As this vinylidene fluoride resin, a vinylidene fluoride homopolymer or a copolymer of vinylidene fluoride and a fluoroolefin (tetrafluoroethylene, hexafluoropropylene, chlorotrifluoroethylene) has been proposed. Also, copolymers of fluoroolefins and cyclohexyl vinyl ether and other various monomers,
It is soluble in organic solvents at room temperature, is transparent and has high gloss when used as a coating, and has excellent properties such as high weather resistance, water and oil repellency, stain resistance, and non-adhesion. It is known to provide a film (for example, JP-A-55-44083)
), Its use is increasing in the field of weather-resistant paints for interiors and exteriors of buildings and the like.

On the other hand, in recent years, from the viewpoints of environmental protection such as air pollution and safety to human bodies, the use of problematic organic solvents has been increasingly regulated, and social demands for water-based paints and powder paints which do not use organic solvents. Is growing. Aqueous dispersion of fluorine resins has been studied. For vinylidene fluoride resins, a method of emulsion-polymerizing an acrylic monomer in the presence of vinylidene fluoride resin particles (Japanese Patent Laid-Open No.
3-8884, JP-A-4-325509) have been proposed.

Aqueous dispersion of copolymers of fluoroolefins with cyclohexyl vinyl ether and other various monomers has been studied, and it has been reported that the copolymers can be produced by emulsion polymerization (JP-A-57-34107). JP-A-61-231044). Further, an aqueous dispersion in which a fluorinated copolymer containing a polymerized unit based on a macromonomer having a hydrophilic site as an essential component is dispersed in water has been proposed (Japanese Patent Application Laid-Open No. 2-225550). It has been reported that this aqueous dispersion has excellent film-forming properties, good mechanical strength of the coating film, and can be produced without using an emulsifier or a hydrophilic organic solvent. .

However, the stability of the aqueous dispersion of the vinylidene fluoride resin is not always good, and the transparency of the coating film is poor due to the crystallinity of the resin. When the crystallinity is lowered for improvement, there is a problem that the glass transition temperature of the coating film is too low and the stain resistance is deteriorated. These problems can be improved by seed polymerization of acrylic monomer,
Not enough. There was also a problem in film forming properties. Further, the cost of the vinylidene fluoride-based resin is increased because it is composed of only a fluoroolefin. Regarding copolymers of fluoroolefins with cyclohexyl vinyl ether and other various monomers, although the transparency and film forming properties of the coating film are good and practically practicable, the use of a liquid monomer requires a slight coating. Further improvement has been desired in that tack occurs in the film.

[0006]

SUMMARY OF THE INVENTION The present invention is to solve the above-mentioned problems of the prior art, and is intended to improve the stability and film-forming properties of an aqueous dispersion and the fluorinated copolymer coating. An object of the present invention is to provide an aqueous dispersion of a fluorocopolymer having excellent mechanical strength and improved weather resistance, water resistance and stain resistance of a coating film.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and according to the present invention, the following inventions are provided.

(1) (a) a polymerized unit based on a fluoroolefin, (b) a polymerized unit based on propylene, and (c) a polymerized unit based on ethylene and / or (d)
An aqueous dispersion comprising a copolymer containing butylene-based polymerized units, wherein a fluorine-based copolymer having a glass transition temperature in the range of -20 ° C to 80 ° C is dispersed in water.

(2) (a) a polymerized unit based on fluoroolefin, (b) a polymerized unit based on propylene, (c)
A copolymer comprising a polymerized unit based on ethylene and / or (d) a polymerized unit based on butylene, and (e) a polymerized unit based on at least one selected from vinyl esters, vinyl ethers, isopropenyl ethers and allyl ethers, Whose glass transition temperature is -20 ° C
An aqueous dispersion, wherein a fluorine-based copolymer having a temperature in the range of 80 ° C is dispersed in water.

(3) (a) a polymerized unit based on a fluoroolefin, (b) a polymerized unit based on propylene, (c)
A polymerization unit based on ethylene and / or (d) a polymerization unit based on butylene, and (f) a general formula: XYZ
(Where X is a radical polymerizable unsaturated group and Y is a hydrophobic 2
Is a copolymer containing polymerized units based on a hydrophilic macromonomer represented by the following formula (I), wherein the glass transition temperature is in the range of -20 ° C to 80 ° C. An aqueous dispersion, wherein the polymer is dispersed in water.

(4) (a) a polymerized unit based on fluoroolefin, (b) a polymerized unit based on propylene, (c)
A polymerization unit based on ethylene and / or (d) a polymerization unit based on butylene, (e) a polymerization unit based on at least one selected from vinyl esters, vinyl ethers, isopropenyl ethers and allyl ethers, and (f) a general formula: X -YZ (where X is a radical polymerizable unsaturated group, Y is a hydrophobic divalent linking group, and Z is a hydrophilic group)
A copolymer containing a polymerized unit based on a hydrophilic macromonomer represented by the following, having a glass transition temperature of −20 ° C.
An aqueous dispersion, wherein a fluorine-based copolymer having a temperature in the range of 80 ° C is dispersed in water.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, preferred embodiments of the present invention will be described in detail. In the present invention, (a) a polymerized unit based on a fluoroolefin, (b) a polymerized unit based on propylene are essential components, and further (c) a polymerized unit based on ethylene and / or (d) a polymerized unit based on butylene. An aqueous dispersion of a fluorocopolymer is used.

Here, the fluorine-based copolymer is preferably constituted by a composition ratio of polymerized units based on the following monomers (hereinafter, indicated by the monomer names). That is, (a) 20-80 mol% of fluoroolefin, (b) 2-70 mol% of propylene, (c) ethylene (5)-(70) mol%, (d) butylene (5)-(70) mol% ,

This composition ratio is more preferably (a) 35-65 mol% of a fluoroolefin, (b) 4-55 mol% of propylene, (c) ethylene (8)-(60) mol%, and (d) butylene. (8) to (60) mol%,

Most preferably, (a) 40 to 60 mol% of a fluoroolefin, (b) 6 to 35 mol% of propylene, (c) ethylene (10) to (35) mol%, (d) butylene (10) to ( 35) mol%.

Here, the composition ratios of the polymerization units (c) ethylene and (d) butylene are shown in parentheses (5),
(8), (10) and the like have the following meanings. That is, as specified in the claims,
At least one of (c) and (d) is always included, and the other may not be included at all, but (5), (8),
(10) and the like indicate the content of the contained component (c) or (d) alone. (C) and (d)
(5), (8), (1)
0) indicates the total content of both components.

When the fluorine-based copolymer of the present invention is used in a coating material, if the proportion of the fluoroolefin polymerized unit (a) is too small, the weather resistance is poor, and if it is too large, the cost is increased as compared with the improvement of the weather resistance. It is undesirably high. The above range is selected in consideration of these.

If the proportion of the polymerized unit (b) is too small, the fluorocopolymer becomes rubbery and the hardness of the coating film becomes insufficient. If it is too large, the melting point becomes too high. Run out. Thus, the above range is selected.

As described above, the polymerized units (c) and (d) may be used simultaneously, or only one of them may be used, but at least one is always used.
If the proportion of (c) and / or (d) is too small, the melting point will be too high, and the crystallization of the coating film will be large and the transparency will be reduced. Conversely, if the amount is too large, the fluorocopolymer becomes rubbery and the hardness is insufficient. The above range is selected as preferable in consideration of these.

In the present invention, examples of the fluoroolefin include trifluoroethylene, chlorotrifluoroethylene, tetrafluoroethylene, trifluoropropylene, tetrafluoropropylene, pentafluoropropylene, hexafluoropropylene, tetrafluorobutylene, pentafluorobutylene and the like. A fluoroolefin having about 2 to 4 carbon atoms containing a fluorine atom is preferable, and a perfluoroolefin is particularly preferable. Most preferably,
It is tetrafluoroethylene. Note that other halogen atoms such as a chlorine atom may be contained together with the fluorine atom.

In the present invention, butylene is
1-butylene, 2-butylene and isobutylene can be used, and isobutylene is most preferred in terms of availability. Further, a mixture thereof may be used.

When the monomer constituting the polymerized unit contained in the fluorine-containing copolymer of the present invention comprises only a monomer which is gaseous at normal temperature and normal pressure, the residual monomer after the polymerization is completed Has the characteristic that it can be easily removed only by purging, and therefore, there is an advantage that coloring and stickiness of the coating film due to the residual monomer do not occur.

The glass transition temperature of the fluorinated copolymer of the present invention is in the range of -20.degree. C. to 80.degree.
70 ° C. If the glass transition temperature is too low, the hardness of the coating film is insufficient, and if it is too high, sufficient fluidity cannot be obtained at the time of heating coating, and the appearance of the coating film is impaired. On the other hand, in the case of vinylidene fluoride resin, the glass transition temperature is low, and the hardness of the coating film is insufficient.

In the present invention, the glass transition temperature is
The exothermic peak when the sample is heated at 10 ° C./min is determined by a scanning differential calorimeter (DSC), and the temperature at that time is determined as the glass transition temperature.

The fluorine-based copolymer of the present invention is selected from (e) vinyl esters, vinyl ethers, isopropenyl ethers and allyl ethers in addition to the polymerized units based on the monomers (a) to (d). It may be a copolymer containing a polymerized unit based on at least one monomer. When polymerized units based on this monomer are contained, not only the pigment dispersibility and the adhesion to the base material are improved, but also the affinity with the acrylic monomer is improved and the transparency of the coating film is improved. It has the feature that weather resistance is improved.

If the amount of the polymerized units based on at least one monomer selected from the above (e) vinyl ester, vinyl ether, isopropenyl ether and allyl ether is too large, the coating film is tacky. On the other hand, if the amount is too small, the effect of improving the pigment dispersibility, the adhesion to the substrate, the affinity with the acrylic monomer, and the like is not sufficiently exhibited. Therefore, the content of the polymerized unit based on the component (e) is preferably 5
~ 20 mol%.

Examples of the vinyl ester include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl caproate, vinyl caprylate, vinyl stearate and the like. Examples of the vinyl ether include methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, and cyclohexyl vinyl ether. Examples of the isopropenyl ether include methyl isopropenyl ether, ethyl isopropenyl ether, propyl isopropenyl ether, butyl isopropenyl ether, and cyclohexyl isopropenyl ether.
Examples of the allyl ether include ethyl allyl ether, propyl allyl ether, butyl allyl ether, and isobutyl allyl ether.

The polymerization unit based on the monomer (e) may contain a reactive group selected from a hydroxyl group, a carboxylic acid group, an epoxy group and a hydrolyzable silyl group. The polymerized unit based on the monomer containing the reactive group contains 2 of the polymerized units based on the monomer (e).
It can be contained in an amount of 0 mol% or more, preferably 25% mol% or more.

Even if the fluorocopolymer has such a reactive group, the stability of the dispersion is not impaired. When the fluorine-based copolymer has a reactive group, when the aqueous dispersion is used as a paint base, by using a curing agent in combination, the resin is crosslinked and has excellent water resistance and solvent resistance. There is an advantage that a coating film having properties can be formed. In this sense, a reactive group can also be considered to correspond to a curable site.

The polymerization unit containing a hydroxyl group is prepared by a method of copolymerizing such a hydroxyl group-containing monomer,
Alternatively, it can be introduced by a method in which a polymer undergoes a polymer reaction to form a polymerization unit containing a hydroxyl group.

Here, the hydroxyl group-containing monomers include hydroxyalkyl vinyl ethers such as hydroxybutyl vinyl ether [HBVE]; hydroxyalkyl allyl ethers such as hydroxyethyl allyl ether; acrylics such as hydroxyethyl acrylate and hydroxyethyl methacrylate. Examples thereof include hydroxyalkyl esters of acid or methacrylic acid.

As a method for polymerizing a polymer to form a polymerized unit containing a hydroxyl group,
Examples include a method of copolymerizing a hydrolyzable vinyl ester after polymerization, and then hydrolyzing to form a hydroxyl group.

On the other hand, the carboxylic acid group-containing polymerized unit is formed by copolymerizing a carboxylic acid group-containing monomer, and forming a carboxylic acid group by reacting a polymer having a hydroxyl group with a dibasic acid anhydride. It can be introduced by methods.

Here, examples of the carboxylic acid group-containing monomer include the following. (1) CH ₂ = CHOR ¹ OCOR ² COOM (2) CH ₂ = CHCH ₂ OR ³ OCOR ⁴ COOM (where R ¹ and R ³ are divalent hydrocarbon groups having 2 to 15 carbon atoms,
R ² and R ⁴ are a saturated or unsaturated linear or cyclic divalent hydrocarbon group, and M is a compound containing a hydrogen atom, a hydrocarbon group, an alkali metal ion or a nitrogen atom. )

The polymerized unit containing an epoxy group can be introduced by copolymerizing a monomer containing an epoxy group. Examples of the epoxy group-containing monomer include epoxy group-containing alkyl vinyl ethers such as glycidyl vinyl ether; epoxy group-containing alkyl allyl ethers such as glycidyl allyl ether; epoxy group-containing alkyl acrylates such as glycidyl acrylate and glycidyl methacrylate or methacrylates. And the like.

The polymerizable unit containing a hydrolyzable silyl group can be introduced by copolymerizing a monomer containing a hydrolyzable silyl group. Examples of the monomer containing a hydrolyzable silyl group include trimethoxyvinylsilane and triethoxyvinylsilane.

In the fluorine-based copolymer of the present invention, in addition to the monomers (a) to (d) or (a) to (e), (f) a general formula: XYZ (here, X is a radical polymerizable unsaturated group, Y is a hydrophobic divalent linking group, and Z is a hydrophilic group.
May be copolymerized.
When polymerized units based on this hydrophilic macromonomer are contained, not only the mechanical stability and chemical stability of the aqueous dispersion are improved, but also the film forming property and the mechanical strength of the coating film are excellent. Further, since no or little emulsifier for stabilization is required, water resistance and stain resistance are improved.

Here, the radical polymerizable unsaturated group X includes a vinyl group (CH ₂ = CH-), an allyl group (CH ₂ = CHCH _2- ),
Propenyl group (CH ₃ CH = C-), isopropenyl group (CH ₂ = C
(CH ₃₎ -), acryloyl group (= CHCO- CH _2), methacryloyl group _{(CH 2 = C (CH 3} ) CO-) may illustrate like.

The hydrophobic divalent linking group Y is preferably a linear or branched hydrocarbon group, a polyoxypropylene group, an alicyclic group such as a cyclohexane ring or a cyclododecane ring, or an aromatic group. The more hydrophobic this linking group is, the higher the compatibility of the hydrophilic macromonomer with other copolymerizable monomers such as fluoroolefin, ethylene and propylene, and the higher the reaction rate of the macromonomer is. As a result, it is possible to obtain an aqueous dispersion of a fluorine-based copolymer having excellent stability without using any or almost no emulsifier for stabilization.

The hydrophilic group Z may be any of ionic, nonionic, amphoteric and a combination thereof. It is desirable to combine a macromonomer having a nonionic or amphoteric hydrophilic group, since the thermal stability is reduced. A nonionic hydrophilic group such as a polyoxyethylene group or a polyoxypropylene / polyoxyethylene group is particularly preferred from the viewpoint of the effect on the strength of the hydrophilic property and the physical properties of the coating film.

The macromonomer is a low molecular weight polymer or oligomer having a radically polymerizable unsaturated group at one terminal. That is, it is a compound having a radical polymerizable unsaturated group at one terminal and having at least two repeating units in order to obtain sufficient stability. Although it depends on the type of the repeating unit, the number of the repeating unit is usually 10
Those having 0 or less are preferably employed from the viewpoint of polymerizability, water resistance and the like.

As the hydrophilic macromonomer, one having a vinyl ether type or allyl ether type at one end is preferable. For example, (1) CH ₂ = CHOCH ₂ -cycloC ₆ H ₁₀ -CH ₂ O (CH ₂ CH ₂ O) _t X (
t represents an integer of 2 to 40, and X represents a hydrogen atom, a lower alkyl group, or a lower acyl group. ), (2) CH ₂ = CHOC ₄ H ₈ -O- (CH ₂ CH (CH ₃ ) O) _u -CH ₂ O (CH ₂ C
H ₂ O) _t X (u is an integer of from 1 to 10, t, X have the same meanings as defined _{above.), (3) CH 2} = CHO-C 4 H 8 over O- (CH ₂ CH ₂ O ) _t X (t, X
Represents the same meaning as described above. ) (4) CH ₂ = CHCH ₂ OC ₄ H ₈ -O- (CH ₂ CH (CH ₃ ) O) _u -CH ₂ O (CH ₂
CH ₂ O) _t X (u, t and X have the same meanings as described above). The binding site of (-cycloC ₆ H _10- ) includes 1,4-, 1,3-, and 1,2-, but 1,4- is usually employed.

Of these, those having a vinyl ether type structure at one end are preferred because they are excellent in alternating copolymerizability with fluoroolefins and the weather resistance of the copolymer coating film is good, and the following are exemplified. You. (1) CH ₂ = CHOC ₄ H ₈ -O- (CH ₂ CH ₂ O) _n H (n is 2 to 40
(2) CH ₂ = CHOCH ₂ -cycloC ₆ H ₁₀ -CH ₂ O- (CH ₂ CH ₂ O)
_n H (n represents the same meaning as described above.) (3) CH ₂ = CHO-cycloC ₆ H ₁₀ -C (CH ₃ ) ₂ -cycloC ₆ H ₁₀ -O-
(CH ₂ CH ₂ O) _n H (n represents the same meaning as described above.)

These hydrophilic macromonomers are produced by a method such as polymerizing formaldehyde with an alkyl vinyl ether or alkyl allyl ether having a hydroxyl group, or subjecting a compound having an alkylene oxide or a lactone ring to ring-opening polymerization. It is possible. It can also be produced by introducing a vinyl ether group, an allyl ether group or the like into the terminal of a hydrophilic polymer such as polyethylene glycol.

The hydrophilic macromonomer is a macromonomer having a chain obtained by radically polymerizing a hydrophilic ethylenically unsaturated monomer and having a radically polymerizable unsaturated group such as vinyl ether or allyl ether at a terminal. Is also good. Such a macromonomer can be produced by the method described by Yamashita et al. In Polym. Bull., 5.335 (1981). That is, by subjecting an ethylenically unsaturated monomer having a hydrophilic group to radical polymerization in the presence of an initiator having a condensable functional group and a chain transfer agent, a polymer having a condensable functional group is produced. Examples of the method include reacting a compound such as glycidyl vinyl ether or glycidyl allyl ether with a functional group of the polymer to introduce a radical polymerizable unsaturated group into a terminal.

The ethylenically unsaturated monomers used for producing the hydrophilic macromonomer include acrylamide, methacrylamide, N-methylolacrylamide,
N-methylol methacrylamide, 2-methoxyethyl acrylate, 2-methoxyethyl methacrylate, diacetone acrylamide, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, polyhydric alcohol Examples include acrylates, methacrylates of polyhydric alcohols, and vinylpyrrolidone.

In addition, a monomer copolymerizable with the ethylenically unsaturated monomer may be used together with the ethylenically unsaturated monomer. As such copolymerizable monomers,
Examples include acrylamide and its derivatives, methacrylamide and its derivatives, N-methylol acrylamide derivatives, diethylene glycol monoethyl ether monoacrylate, triethylene glycol monomethyl ether monoacrylate, phosphate esters of 2-hydroxyethyl acrylate, and butoxyethyl acrylate.

Examples of the polymerization initiator used for producing the hydrophilic macromonomer include 4,4′-azobis-4-cyanovaleric acid, 2,2′-azobis-2-amidinopropane hydrochloride, persulfate Potassium, ammonium persulfate, azobisisobutyronitrile, benzoyl peroxide, and the like.

In the fluorine-based copolymer of the present invention,
The polymerized unit based on the hydrophilic macromonomer is 0.1 to 25.
Molar%, preferably 0.3 to 20% by mole.

When the content is too small, the mechanical stability and chemical stability of the aqueous dispersion cannot be remarkably improved, and when too large, the weather resistance and water resistance of the coating film are poor. Is not preferred.

The aqueous dispersion of the present invention is obtained by dispersing a fluorinated copolymer in water. The aqueous dispersion of the present invention is excellent in dispersion stability without using an emulsifier usually used in a fluorine-based copolymer aqueous dispersion, but does not exclude the use of an emulsifier. As the emulsifier, a nonionic emulsifier or an anionic emulsifier can be used alone or in combination. Examples of the nonionic emulsifier include an alkylphenol ethylene oxide adduct, a higher alcohol ethylene oxide adduct, and an ethylene oxide / propylene oxide block copolymer.
Examples of the anionic emulsifier include an alkylbenzene sulfonate, an alkylnaphthalene sulfonate, a higher fatty acid salt, an alkyl sulfate, an alkyl ether sulfate, and a phosphate.

The above-mentioned emulsifier is usually used by adding at the time of polymerization, but the same kind of emulsifier and / or different kinds of emulsifier may be added to the aqueous dispersion after polymerization.

The emulsifiers to be added to the aqueous dispersion after polymerization include, in addition to the above emulsifiers, alkali metal salts of dialkylsulfosuccinic acids such as sodium dioctylsulfosuccinate and sodium dinonylsulfosuccinate, and ethylene glycol, Examples thereof include a combination with an alkylene glycol such as propylene glycol. The addition of these alkali metal salts of dialkylsulfosuccinic acid and alkylene glycol improves the mechanical and thermal stability of the aqueous dispersion.

The initiation of the emulsion polymerization in the present invention is carried out by adding a polymerization initiator in the same manner as in the usual initiation of emulsion polymerization.
As the polymerization initiator, a normal radical initiator can be used, but a water-soluble initiator is particularly preferably used,
Specifically, a redox initiator consisting of a persulfate such as ammonium persulfate, hydrogen peroxide or a combination thereof with a reducing agent such as sodium hydrogen sulfite or sodium thiosulfate, and further a small amount of iron or ferrous iron salt,
Inorganic initiators in the presence of silver sulfate, etc., or dibasic acid peroxides such as disuccinic peroxide, diglutaric peroxide, azobisisobutylamidine hydrochloride and azobisisobutyronitrile Agents are exemplified.

The amount of the polymerization initiator to be used can be appropriately changed depending on the kind thereof, emulsion polymerization conditions and the like, but is usually 0.005 to 100 parts by weight per 100 parts by weight of the monomer to be emulsion-polymerized.
About 0.5 part by weight is preferable. Further, these polymerization initiators may be added all at once, or may be added in portions as needed.

For the purpose of increasing the pH of the emulsion, p
An H adjuster may be used. Examples of the pH adjuster include inorganic bases such as sodium carbonate, potassium carbonate, sodium hydrogen orthophosphate, sodium thiosulfate, and sodium tetraborate, and organic bases such as triethylamine, triethanolamine, dimethylethanolamine, and diethylethanolamine. Is done.

The amount of the pH adjuster 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 higher the polymerization rate tends to be.

The emulsion polymerization initiation temperature is appropriately selected depending on the type of the polymerization initiator.
00 ° C, particularly about 10 to 90 ° C, is preferably employed.
The polymerization temperature is about 20 to 120 ° C. Although the reaction pressure can be appropriately selected, it is usually preferable to employ 0.1 to 10 MPa, particularly preferably 0.2 to 5 MPa.

In this production method, additives such as a monomer, water, an emulsifier, a polymerization initiator and the like may be charged as they are, and polymerization may be carried out. For the purpose of improving various properties such as gloss of the coating film and the like, pre-emulsification may be performed using a stirrer such as a homogenizer before adding a polymerization initiator, and then polymerization may be performed by adding an initiator. In addition, the method of charging the monomer in its entirety into the reactor at once, the method of continuously charging the total amount of the monomer, the method of dividing and charging the total amount of the monomer, Various methods can be adopted, such as a method in which a part is charged and reacted first, and then the remaining part is divided or continuously charged. In the case of divisional addition, the monomer composition may be different.

The fluorine-based copolymer of the present invention is obtained by further emulsifying a monomer having the same combination and composition as the particles in the presence of particles of the fluorine-based copolymer which have been polymerized in advance. It may be polymerized. Pre-existing copolymer particles in water make it easier to absorb gaseous monomers and improve the polymerization rate. Further, at that time, the stability of the dispersion can be further improved by preliminarily polymerizing and diluting the particles of the fluorine-based copolymer and then performing emulsion polymerization.

In this case, it is desirable to carry out the polymerization at a ratio of 100 to 10,000 parts by weight of the mixture of monomers with respect to 100 parts by weight of the fluorine-based copolymer particles previously charged during the polymerization. If the proportion of the fluorocopolymer particles charged in advance is too low, the effect of improving the polymerization rate is small, and if it is too high, the yield of the aqueous dispersion obtained by one polymerization operation is reduced, which is not economical.

In order to further improve the gas absorption of the monomer, methanol, ethanol, isopropanol, n
Alcohols such as -butanol, isobutanol and t-butanol; and hydrophilic organic compounds such as alkylene glycols such as ethylene glycol and propylene glycol may be added during polymerization. In this case, the amount of addition is preferably 0.1 to 10% by weight based on the water of the aqueous dispersion. More preferably, it is 1 to 5%.

If the addition amount is smaller than this, the gas absorbing effect is small, and if it is too large, the content of volatile organic compounds increases, which adversely affects the environment.

In the aqueous dispersion in which the above-mentioned fluorine-containing copolymer is dispersed, a monomer of an alkyl (meth) acrylate (hereinafter also referred to as (meth) acrylate) is used as a main component. Can be emulsion-polymerized. Emulsion polymerization of a radical polymerizable monomer having a (meth) acrylate monomer as a main component in an aqueous dispersion in which such a fluorine-based copolymer is dispersed, This is what should be called post-reaction to a fluorine-based copolymer or so-called seed polymerization using the same as seed particles. In the process of emulsion polymerization, radical polymerization mainly comprising a (meth) acrylate monomer is used. Some interaction such as penetration and swelling of the hydrophilic monomer into the fluorine-based copolymer occurs, so that in the final aqueous dispersion of the fluorine-based copolymer, both dispersions are separately prepared. It is expected that a copolymer in which a fluorine-based copolymer and a copolymer containing a (meth) acrylate monomer as main components are more uniformly dispersed can be obtained as compared with a mixed product.

As described above, the characteristics such as the weather resistance of the fluorinated copolymer were maintained by the seed polymerization of the radical polymerizable monomer mainly composed of the (meth) acrylate monomer. As it is, mechanical stability, chemical stability,
Film forming properties, pigment dispersibility, and workability can be further improved.

The alkyl (meth) acrylate preferably has 1 to 18 carbon atoms in the alkyl group. Examples thereof include methyl (meth) acrylate, ethyl (meth) acrylate, and (meth) acrylic acid. Propyl acid,
N-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, n-amyl (meth) acrylate, isoamyl (meth) acrylate,
Examples thereof include n-hexyl (meth) acrylate, isohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and lauryl (meth) acrylate. Among them, a (meth) acrylate having an alkyl group having 1 to 5 carbon atoms is particularly preferable.

Further, together with the (meth) acrylate, a monomer copolymerizable therewith may be used in an amount of 50 mol% or less, preferably 25 mol% or less of the acrylate.

The monomers copolymerizable with the (meth) acrylic acid ester include (meth) acrylic acid, maleic acid,
Carboxyl group-containing monomers such as crotonic acid; (meth)
Acrylamide, N-methyl (meth) acrylamide,
Amide compounds such as N-methylol (meth) acrylamide, N-butoxymethyl (meth) acrylamide;
Hydroxyl-containing monomers such as hydroxyethyl (meth) acrylate and hydroxypropyl (meth) acrylate; epoxy-containing monomers such as glycidyl (meth) acrylate; γ-trimethoxysilane (meth) acrylate; Radical polymerizable monomers having at least one functional group such as a hydrolyzable silyl group-containing monomer such as (meth) acrylic acid γ-triethoxysilane are exemplified.

The copolymer containing (meth) acrylic acid ester as a main component is per 100 parts by weight of the fluorocopolymer,
The amount is 5 to 200 parts by weight, preferably 10 to 100 parts by weight, more preferably 20 to 50 parts by weight. Accordingly, when the above-mentioned so-called seed polymerization is employed, 5-200 parts by weight of a monomer containing (meth) acrylic acid as a main component is charged into a reaction vessel in the presence of 100 parts by weight of a fluorocopolymer and emulsified. Polymerization will be performed.

Emulsion polymerization conditions for the copolymer containing (meth) acrylic acid ester as a main component can be adopted according to the above-mentioned emulsion polymerization conditions for the fluorinated copolymer.

The glass transition temperature (hereinafter, also referred to as the composited glass transition temperature) of the composite particles of the fluorine-based copolymer and the copolymer containing (meth) acrylate as a main component is as follows. It is preferably in the range of -20 to 80 ° C, more preferably 0 to 70 ° C. If the glass transition temperature is too low, the film will be tacky, and if it is too high, the flexibility of the film will be impaired.

The aqueous dispersion of the present invention can be used as it is as an aqueous paint, but if necessary, a coloring agent, a plasticizer, an ultraviolet absorber, a leveling agent, a defoaming agent, a pigment dispersant, a thickener Additives that are usually added to aqueous paints, such as anti-cissing agents, skin burrs, and curing agents, may be mixed. Further, a metallic pigment such as an aluminum paste may be used. Examples of the coloring agent include dyes, organic pigments, and inorganic pigments. Conventionally known plasticizers,
For example, a low-molecular-weight plasticizer such as dioctyl phthalate, a high-molecular-weight plasticizer such as a vinyl polymer plasticizer, and a polyester-based plasticizer can be used. As the film forming aid, polyhydric alcohol monoalkyl ethers such as dipropylene glycol-n-butyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, and organic acid esters are used. As the curing agent, for example, a blocked isocyanate such as hexamethylene diisocyanate trimer, and a melamine resin such as methylated melamine and methylolated melamine are used. Further, a pH adjuster may be added to improve the stability of the aqueous dispersion.

[0073]

EXAMPLES The present invention will be specifically described below with reference to synthesis examples and examples, but the present invention is not limited to these examples and the like. The number of parts in the following examples indicates parts by weight unless otherwise specified.

(Synthesis Example 1) 675 g of ion-exchanged water was placed in a stainless steel autoclave having a volume of 1.3 L with a stirrer.
20.3 g of an anionic emulsifier (sodium lauryl sulfate: manufactured by Nikko Chemical Co., Ltd.) and a nonionic emulsifier (N-112)
0; manufactured by Nippon Emulsifier Co., Ltd.) and 33 g of t-butanol were charged, and air was removed by repeating deaeration with a vacuum pump and pressurization with nitrogen gas. Next, 64.8 g of tetrafluoroethylene, 1.8 g of propylene, and 3.4 g of ethylene were introduced into the autoclave.

When the temperature in the autoclave reached 65 ° C., the pressure showed 2.48 MPa. Thereafter, 5.8 cc of a 20% aqueous solution of ammonium persulfate was added to start the reaction. While maintaining the pressure by pressurizing with the decrease in pressure, 52 mol% of tetrafluoroethylene and propylene 3
430 g of a mixed gas of 2 mol% and 16 mol% of ethylene was continuously added to continue the reaction.

During the reaction, ammonium persulfate 2
12 cc of a 0% aqueous solution was continuously added. Eight hours later, the supply of the mixed gas was stopped, and the autoclave was cooled with water to reach room temperature. After that, unreacted monomers were purged, and the autoclave was opened to obtain an aqueous dispersion having a solid content of 39.4%.

The resulting aqueous dispersion was settled in a centrifuge, and the polymer was filtered through a glass filter.
After removing water for 5 hours under reduced pressure of mHg, the mixture was pulverized with an impact hammer mill to obtain a powder of a fluorine-based copolymer. The result of compositional analysis of this copolymer by ¹³ C-NMR showed that the polymerization unit was 52 mol% based on tetrafluoroethylene, the polymerization unit was 32 mol% based on propylene, and the polymerization unit was 16 mol% based on ethylene. The glass transition temperature was 12.7 ° C.

(Synthesis Example 2) Ion-exchanged water 1010 was placed in an autoclave with a stainless steel stirrer having an internal volume of 2.5 L.
Parts, 2.2 parts of potassium carbonate (K ₂ CO ₃ ), 2.2 parts of nonionic emulsifier (N-1110; manufactured by Nippon Emulsifier Co.), 1.1 parts of anionic emulsifier (sodium lauryl sulfate),
46.6 g of t-butanol was charged, and air was removed by repeating deaeration with a vacuum pump and pressurization with nitrogen gas. Next, 188 g of tetrafluoroethylene, 3.8 g of propylene, 8 g of ethylene, and 5.1 g of isobutylene were introduced into the autoclave.

When the temperature in the autoclave reached 70 ° C., the pressure showed 1.54 MPa. Thereafter, 2 cc of a 25% aqueous solution of ammonium persulfate was added to start the reaction. While maintaining the pressure as the pressure was reduced, 530 g of a mixed gas of 50 mol% of tetrafluoroethylene, 10 mol% of propylene, 30 mol% of ethylene, and 10 mol% of isobutylene was continuously added to continue the reaction.

During the reaction, ammonium persulfate 2
30 cc of a 5% aqueous solution was continuously added. After 10 hours, the supply of the mixed gas was stopped and the autoclave was cooled with water to reach room temperature. After that, unreacted monomers were purged, and the autoclave was opened to obtain an emulsion having a concentration of 34.5%. The obtained emulsion was settled by a centrifugal separator, and the polymer was filtered with a glass filter and water was removed under reduced pressure of 4 mmHg for 5 hours, and then pulverized with an impact hammer mill to obtain a powder of a fluorocopolymer. I got The result of composition analysis of this copolymer by ¹³ C-NMR was as follows: 54 mol% of a polymer unit based on tetrafluoroethylene, 16 mol% of a polymer unit based on propylene, 20 mol% of a polymer unit based on ethylene, and a polymer unit based on isobutylene. 10%. The glass transition temperature was 12.1 ° C.

(Synthesis Example 3) A 200-mL glass flask equipped with a thermometer, a stirrer, reflux, and a condenser was prepared as shown in Table 1.
In the same manner as in Example 1 except that the monomer having the composition shown in Example 3 was used, 70 g of an aqueous dispersion having a solid content concentration of 32.0% by weight was charged (the amount of the fluorine-based copolymer in the dispersion was 24 g. The mixture was heated to 80 ° C. When the temperature reached 80 ° C., 1 g of 10 g of methyl methacrylate, 1.2 g of isobutyl methacrylate, 0.04 g of a nonionic emulsifier (N-1110; manufactured by Nippon Emulsifier Co.) and 0.02 g of an anionic emulsifier (sodium lauryl sulfate) were added. % Aqueous solution was added dropwise over 1 hour. Immediately thereafter, 1 mL of a 2% by weight aqueous solution of ammonium persulfate was added to start the reaction. After a reaction time of 3 hours, the temperature in the flask was raised to 90 ° C., and the reaction was further performed for 1 hour to complete the polymerization. The fluororesin and the methacrylate polymer were in a ratio of 2: 1 (weight ratio).
An aqueous dispersion having a solid concentration of 40.8% by weight was obtained. The glass transition temperature of the composite particles was 62.3 ° C.

(Synthesis Example 4) In a 1.3 L autoclave equipped with a stainless steel stirrer, 90 parts of the fluorinated aqueous dispersion obtained in Synthesis Example 2, 616 parts of ion-exchanged water, and potassium carbonate (K ₂ CO ₃₎ ) 3.4 parts, nonionic emulsifier (N-1120; Nippon Emulsifier Co.) 20.4 parts, anionic emulsifier (sodium lauryl sulfate) 6.8 parts, t-
33 g of butanol was charged, and air was removed by repeating deaeration with a vacuum pump and pressurization with nitrogen gas. next,
52.6 g of tetrafluoroethylene, 1.3 of propylene
g and 2.1 g of ethylene were introduced into the autoclave.

When the temperature in the autoclave reached 65 ° C., the pressure showed 2.62 MPa. Thereafter, 2 cc of a 15% aqueous solution of ammonium persulfate was added to start the reaction. While maintaining the pressure as the pressure decreased, 410 g of a mixed gas of 53 mol% of tetrafluoroethylene, 27 mol% of propylene and 20 mol% of ethylene was continuously added to continue the reaction.

During the reaction, ammonium persulfate 1
30 cc of a 5% aqueous solution was continuously added. After 18 hours, the supply of the mixed gas was stopped, and the autoclave was cooled with water to reach room temperature. After that, unreacted monomers were purged, and the autoclave was opened to obtain an emulsion having a concentration of 34.5%. The obtained emulsion was settled by a centrifugal separator, and the polymer was filtered with a glass filter and water was removed under reduced pressure of 4 mmHg for 5 hours, and then pulverized with an impact hammer mill to obtain a powder of a fluorocopolymer. I got The result of composition analysis of this copolymer by ¹³ C-NMR was as follows: 53 mol% of polymer units based on tetrafluoroethylene, 27 mol% of polymer units based on propylene, and 20 mol% based on ethylene. The glass transition temperature is 16.6 ° C.
Met. Table 1 shows the above results.

(Synthesis Examples 5 to 10) The aqueous dispersion of the fluorine-based copolymer was changed according to the method described in Synthesis Examples 1 to 3 except that the monomer composition used for the emulsion polymerization was changed as shown in Tables 1 and 2. A liquid was obtained.

[0086]

[Table 1]

[0087]

[Table 2]

The abbreviations in Tables 1 and 2 are as follows. _{EOVE-1: CH 2 = CHOC} 4 H 8 -O- (CH 2 CH 2 O) n H ( average molecular weight _{520) EOVE-2: CH 2} = CHOCH 2 -cycloC 6 H 10 -CH 2 O- (CH 2 CH ₂ O)
_n H (average molecular weight 830) HBVE: 4-hydroxybutyl vinyl ether

The glass transition temperature was determined by determining the exothermic peak when the sample was heated at a rate of 10 ° C./min using a scanning differential calorimeter (DSC), and setting the temperature at that time as the glass transition temperature.

In the composition of a, b, c, d, e, and f, for example, the composition of tetrafluoroethylene is “90 /
"52" means that the numerator "90" has a composition of 90 mol% in the feed monomer and the denominator "5"
"2" indicates that the polymerization unit based on tetrafluoroethylene in the copolymer is 52 mol%.

(Examples 1 to 9, Comparative Example 1) 71 parts of the aqueous dispersion of the fluorocopolymer obtained above, 5.4 parts of a film-forming auxiliary, 0.3 part of a thickener, and a dispersant 0.8 parts, defoamer 0.6 parts and ion-exchanged water 10.3 parts were used in the amounts shown in Table 2 to formulate a clear paint. In addition, the film-forming auxiliary is Cs-
12 (manufactured by Chisso), the thickener is Leobis CR (manufactured by Hoechst Gosei), the dispersant is Noscosperse 44-C (manufactured by San Nopco), and the defoaming agent is FS Antifoam 90 (manufactured by Dow Corning).

These paints were applied on an aluminum plate to form a film having a dry thickness of 4
0μm by air spray, 80 ℃ 3
After drying for 0 minutes, a test piece was obtained. When the aqueous dispersion of Example 10 was used, no test piece was obtained without forming a film. The test pieces were tested for weather resistance, water resistance and stain resistance.

Evaluation of weather resistance: When the gloss was significantly reduced after 3000 hours in a QUV test using a fluorescent ultraviolet weather resistance tester manufactured by Q Panel Co., it was evaluated as x, and when the gloss was not significantly reduced, it was evaluated as ○.

Water resistance evaluation: After immersion in hot water at 60 ° C. for one week, the coating was evaluated for blistering or peeling.

Stain resistance: When exposed outdoors at 45 ° on the south side for 1 year and the color difference between the preservation plate and the sprayed water was 5 or less, ○,
Those exceeding 5 were rated as x. The results are shown in Table 3.

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[Table 3]

[0097]

The aqueous dispersion of the fluorocopolymer of the present invention gives a coating film having excellent weather resistance, stain resistance and water resistance, and is extremely useful as a raw material for a weather-resistant aqueous coating.

The aqueous paint using the aqueous dispersion of the present invention is basically based on a stable aqueous dispersion which does not use an organic solvent. Applicable to the application. For example, it is particularly useful for weather-resistant coating of exterior inorganic building materials such as glass, metal and cement.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08J 3/075 CEY C08F 2/24 A C08L 55/00 2/44 C C09D 123/02 290/06 127 / 12 C08J 3/03 CEW // C08F 2/24 CEY 2/44 290/06 (C08F 214/18 210: 02 210: 06 210: 08)

Claims (8)

[Claims] 1. A polymerized unit based on (a) a fluoroolefin, (b) a polymerized unit based on propylene, and (c) a polymerized unit based on ethylene and / or (d)
An aqueous dispersion comprising a copolymer containing butylene-based polymerized units, wherein a fluorine-based copolymer having a glass transition temperature in the range of -20 ° C to 80 ° C is dispersed in water. 2. Polymerized units based on (a) fluoroolefins, (b) polymerized units based on propylene, (c) polymerized units based on ethylene and / or (d) polymerized units based on butylene, and (e) vinyl esters , A copolymer containing polymerized units based on at least one selected from vinyl ether, isopropenyl ether and allyl ether, having a glass transition temperature of -20 ° C to 80 ° C.
An aqueous dispersion, wherein a fluorine-based copolymer having a temperature in the range of ° C is dispersed in water. 3. A polymerization unit based on (a) a fluoroolefin, (b) a polymerization unit based on propylene, (c) a polymerization unit based on ethylene and / or (d) a polymerization unit based on butylene, and (f) a general formula. : XYZ (where X is a radical polymerizable unsaturated group, Y is a hydrophobic divalent linking group, and Z is a hydrophilic group) containing a polymerized unit based on a hydrophilic macromonomer. An aqueous dispersion comprising a polymer, wherein a fluorine-based copolymer having a glass transition temperature in a range of -20 ° C to 80 ° C is dispersed in water. 4. A polymer unit based on (a) a fluoroolefin, (b) a polymer unit based on propylene, (c) a polymer unit based on ethylene and / or (d) a polymer unit based on butylene, (e) a vinyl ester, Polymerized units based on at least one selected from vinyl ether, isopropenyl ether and allyl ether; and (f)
A polymerization unit based on a hydrophilic macromonomer represented by a general formula: XYZ (where X is a radical polymerizable unsaturated group, Y is a hydrophobic divalent linking group, and Z is a hydrophilic group) A copolymer having a glass transition temperature of -20 ° C to 80 ° C.
An aqueous dispersion characterized in that the fluorocopolymer in the range of 1) is dispersed in water. 5. In the presence of 100 parts by weight of the particles of the fluorocopolymer according to claim 1, 100 to 10,000 parts by weight of a mixture of the same monomer combination as the particles. An aqueous dispersion obtained by emulsion polymerization. 6. A compound having a carbon number of 1 to 1 in the presence of 100 parts by weight of particles of the fluorocopolymer according to claim 1.
Radical polymerizable monomer mixture 5 to 20 containing (meth) acrylic acid alkyl ester of alkyl group 8 as a main component
An aqueous dispersion obtained by emulsion polymerization of 0 parts by weight. 7. A compound having a carbon number of 1 to 1 in the presence of 100 parts by weight of particles of the fluorocopolymer according to claim 1.
5 to 200 parts by weight of a mixture of a (meth) acrylic acid alkyl ester of an alkyl group of No. 8 and a radical polymerizable monomer having at least one functional group selected from a carboxyl group, a hydrolyzable silyl group and a hydroxyl group. Aqueous dispersion obtained by emulsion polymerization. 8. The glass transition temperature of a composite particle of a fluorine-based copolymer and a copolymer containing (meth) acrylate as a main component is in the range of −20 ° C. to 80 ° C. 8. The aqueous dispersion according to 7.