JPH05117481A - Aqueous dispersion - Google Patents

Abstract

PURPOSE:To provide an aq. coating compsn. useful as a coating base capable of giving a coating film excellent in weatherability, stain resistance and water repellency. CONSTITUTION:A fluorine-contg. copolymer comprising as the indispensable components a polymeric unit(s) based on a fluoroolefin, a polymeric unit(s) based on a macromonomer having a hydrophilic site and a polymeric unit(s) based on a perfluoroalkyl vinyl ether is dispersed in water.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an aqueous dispersion.

[0002]

2. Description of the Related Art Conventionally, a copolymer composed of a fluoroolefin, cyclohexyl vinyl ether and various other monomers is soluble in an organic solvent at room temperature, has a transparent and high gloss when used as a paint, and It is known to give a coating film with the excellent properties of fluororesin such as high weather resistance, water and oil repellency, stain resistance, non-adhesiveness (for example, JP-A-55-44083), Its use in the field is increasing.

On the other hand, since the use of hydrophilic organic solvents is being regulated from the viewpoint of air pollution in recent years, there is an increasing demand for water-based paints and powder paints that do not use hydrophilic organic solvents. Fluorocarbon resins have also been studied for that purpose, and it has been reported that those having no functional group can be produced by emulsion polymerization.
(JP-A-55-25411)

Further, those obtained by emulsion-polymerizing a fluorine-containing copolymer having a hydroxyl group are disclosed in JP-A-57-34107 and JP-A-57-34107.
61-231044. However, in these methods, it was essential to use an emulsifier and a hydrophilic organic solvent together. In these methods, when either or both of the emulsifier and the hydrophilic organic solvent are not used,
There was a problem that an aqueous dispersion could not be obtained, or even if an aqueous dispersion was obtained, the mechanical and chemical stability was extremely poor and aggregation and sedimentation occurred during storage.

Further, the aqueous dispersions obtained by these methods may have poor film-forming properties, and the resulting coating film may have poor stain resistance.

[0006]

SUMMARY OF THE INVENTION The present invention is intended to solve the above-mentioned problems of the prior art. That is, it is an object of the present invention to newly provide an aqueous dispersion having excellent film-forming properties and improved coating film water resistance and stain resistance.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and comprises a polymerized unit based on a fluoroolefin, a polymerized unit based on a macromonomer having a hydrophilic moiety, and a perfluoro. It is intended to provide an aqueous dispersion in which a fluorine-containing copolymer containing a polymerized unit based on an alkyl vinyl ether as an essential component and a water-soluble resin are dispersed in water.

In the present invention, fluoroolefins having about 2 to 4 carbon atoms such as vinylidene fluoride, trifluoroethylene, chlorotrifluoroethylene, tetrafluoroethylene, pentafluoropropylene and hexafluoropropylene are preferably used as the fluoroolefin. To be done. Perhalo olefins are particularly preferred.

In the aqueous dispersion of the present invention, it is important that the fluorinated copolymer has polymerized units based on a macromonomer having a hydrophilic site. Since this unit is included as an essential constituent component of the fluorinated copolymer, not only the mechanical and chemical stability of the aqueous dispersion is improved, but also the film-forming property and the water resistance of the coating film are improved. You can do it.

The hydrophilic part of the macromonomer having a hydrophilic unit in the invention means a part having a hydrophilic group,
Alternatively, it represents a site having a hydrophilic bond and a site composed of a combination thereof.

The hydrophilic group is ionic, nonionic,
It may be either amphoteric or a combination thereof, but in the case where the hydrophilic site is composed only of a unit having an ionic hydrophilic group, there is a problem in the chemical stability of the aqueous dispersion. Undesirably, it is desirable to combine with a site having a nonionic or amphoteric hydrophilic group or to combine with a site having a hydrophilic bond.

The macromonomer is 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 having at least two repeating units. Depending on the type of repeating unit,
Usually, those having 100 or less repeating units are preferably adopted from the viewpoint of polymerizability and water resistance.

As the macromonomer having a hydrophilic moiety, for example, (1) CH ₂ = CHO (CH ₂ ) _k [O (CH ₂ ) _m ] _n OX (k is 1 to 10, m is 1 to 4, n Is an integer from 2 to 20, X is H
Or a lower alkyl group) (2) CH ₂ = CHCH ₂ O (CH ₂ ) _k [O (CH ₂ ) _m ] _n OX (k, m, n, X are the same as those in formula (1) ) (3) CH ₂ = CHO (CH ₂ ) _k (OCH ₂ CH ₂ ) _m (OCH ₂ CH (CH ₃ )) _n OX (k is 1 to 10, m is 2 to 20, n is 0 to 20) Integer, X is H
Or a lower alkyl group, and the oxyethylene unit and the oxypropylene unit may be arranged in any type of block and random) (4) CH ₂ = CHCH ₂ O (CH ₂ ) _k (OCH ₂ CH ₂ ). _m (OCH ₂ CH (CH ₃ )) _n OX (k, m, n, X are the same as those in formula (3), and the oxyethylene unit and the oxypropylene unit are arranged in either block or random type. (5) CH ₂ = CHO (CH ₂ ) _n O (CO (CH ₂ ) _m O) _k H (n is 1 to 10, m is 1 to 10, k is 1 to 30), etc. Examples include polyether polyesters having a radically polymerizable unsaturated group at one end.

Among them, those having a vinyl ether type structure at one end are excellent in copolymerizability with fluoroolefins and are preferably used. It is particularly preferable that the polyether chain portion is composed of an oxyethylene unit or an oxyethylene unit and an oxypropylene unit because it has excellent hydrophilicity.

In addition, at least 2 oxyethylene units are included.
Unless it has one, various properties such as stability cannot be achieved. Also, if the number of oxyalkylene units is too large, the water resistance and weather resistance of the coating film deteriorate, which is not preferable.

The macromonomer having such a hydrophilic portion is produced by a method such as polymerizing formaldehyde or diol with vinyl ether or allyl ether having a hydroxyl group or ring-opening polymerization of a compound having an alkylene oxide or lactone ring. Is possible.

Further, as the macromonomer having a hydrophilic portion, a macromonomer having a chain in which a hydrophilic ethylenically unsaturated monomer is radically polymerized and having a radically polymerizable unsaturated group such as vinyl ether or allyl ether at a terminal is used. It may be.

Yamashita et al.
It can be produced by the method described in Lym. 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, and A method of reacting a functional group of this polymer with a compound such as glycidyl vinyl ether or glycidyl allyl ether to introduce a radically polymerizable unsaturated group at the terminal is exemplified.

The ethylenically unsaturated monomer used for the production of this macromonomer includes acrylamide, methacrylamide, N-methylol acrylamide, N-methylol methacrylamide, 2-methoxyethyl acrylate, 2-methoxyethyl methacrylate and diacetone acrylamide. , Hydroxyethyl acrylate, fodoxypropyl acrylate, hydroxybutyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, acrylic acid esters of polyhydric alcohols and methacrylic acid esters of polyhydric alcohols, and vinylpyrrolidone.

In addition to the above, as a copolymerizable monomer,
There are 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 the like.

As the initiator used for the production of this macromonomer, 4,4'-azobis-4-cyanovaleric acid, 2,2'-azobis-2-amidinopropane hydrochloride, potassium peroxide, ammonium peroxide are used. , Azobisisobutyronitrile, benzoyl peroxide and the like.

The fluorine-containing copolymer in the present invention has a polymerized unit based on perfluoroalkyl vinyl ether. Here, as the perfluoroalkyl vinyl ether, a compound represented by CF = CF ₂ OR _f is adopted. In the above formula, R _f is a linear, branched or cyclic perfluoroalkyl group or perfluoroether group having 1 to 8 carbon atoms. Specifically, -CF ₃ , -CF ₂ CF ₃ , -CF
_{2 CF 2 CF 3, -CF 2} CF (CF 3) 2, etc. _{-CF 2 CF (C 3 F)} OCF 2 CF 2 CF 3 and the like.

The copolymerization ratio is preferably in the range of 1 to 50 mol%. If it is 1 mol% or less, the water repellency, oil repellency and stain resistance are not sufficient, and if it is 50 mol% or more, the compatibility of the pigment cannot be obtained, which is not preferable. Further, even if it is contained in an excessively large amount, stain resistance corresponding to the content cannot be obtained, which is not economically preferable. Particularly, 3 to 20 mol% is preferable.

The fluorinated copolymer in the present invention comprises 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 addition to the above-mentioned two types of units. May be included.

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

Further, the polymerized unit containing a hydroxyl group is a method of copolymerizing a monomer containing a hydroxyl group,
Alternatively, there is a method of polymerizing a polymer to form a unit containing a hydroxyl group. Here, as the hydroxyl group-containing monomer, hydroxyalkyl vinyl ethers such as hydroxybutyl vinyl ether, hydroxyalkyl allyl ethers such as hydroxyethyl allyl ether, and hydroxy or acrylic acid such as hydroxyethyl acrylate and hydroxyethyl methacrylate are used. Examples thereof include alkyl ester, hydroxyalkyl vinyl ester, and hydroxyalkyl allyl ester.

As a method of polymerizing a polymer to form a unit containing a hydroxyl group, after polymerizing hydrolyzable vinyl esters after polymerization,
An example is a method of forming a hydroxyl group by hydrolysis.

The polymerized unit containing a carboxylic acid group is formed by a method of copolymerizing a monomer containing a carboxylic acid group, and a polymer having a hydroxyl group is reacted with a dibasic acid anhydride to form a carboxylic acid group. There is a way to do it.

Here, as the carboxylic acid group-containing monomer, CH ₂ = CHOR ¹ OCOR ² COOM CH ₂ = CHCH ₂ R ³ OCOR ⁴ COOM (R ¹ and R ³ are alkyl groups having 2 to 15 carbon atoms) , R ² , R ⁴ are
A saturated or unsaturated linear or cyclic hydrocarbon group,
M is a compound containing hydrogen, an alkali metal or nitrogen. ) Etc. are illustrated.

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, glycidyl acrylate and glycidyl methacrylate. Examples thereof include epoxy group-containing alkyl acrylates or methacrylates.

The carbonyl group can be introduced by copolymerizing a carbonyl group-containing monomer, and the hydrazine residue is added to the carbonyl group-containing polymer by dicarboxylic acid dihydrazide (eg, isophthalic acid dihydrazide, adipic acid dihydrazide). ) Or hydrazine hydrate is blended in an amount of 0.02 to 1 mol per mol of the carbonyl group, and the mixture is heated and reacted.

The fluorine-containing copolymer in the present invention may contain, in addition to the above units, units based on monomers copolymerizable with these. Examples of such a monomer 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 octanoic acid vinyl ester, styrene and vinyl. Vinyl compounds such as aromatic vinyl compounds such as toluene,
Examples thereof include 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 used.

Here, the olefins have 2 to 10 carbon atoms.
The vinyl ethers, vinyl esters, allyl ethers and allyl esters having a linear, branched or alicyclic alkyl group having about 2 to 15 carbon atoms are preferably adopted. ..

In such a monomer, at least part of hydrogen bonded to carbon may be replaced with fluorine.

The fluorine-containing copolymer in the present invention contains 20 to 80 mol% of polymerized units based on fluoroolefin,
It is preferable that the ratio of polymerized sites based on the macromonomer having a hydrophilic site is 0.1 to 25 mol%.

If the amount of the polymerized units based on the fluoroolefin is too small, the weather resistance will not be sufficiently exhibited, and if it is too large, the water dispersibility will be extremely deteriorated, which is not preferable. It is particularly preferably 30 to 70 mol%.

If the number of polymerized units based on the macromonomer having a hydrophilic portion 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 poor, such being undesirable. In particular, in order to achieve an extremely excellent effect of forming a film, it is preferable that this unit is contained in a proportion of 0.3 to 20 mol%.

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 decreases, and when the coating film is cured, it becomes hard and brittle,
The residual hydroxyl group may undesirably lower the water resistance.

When the polymerized unit based on the macromonomer having a hydrophilic portion has a hydroxyl group, the unit is a polymerized unit based on the macromonomer having a hydrophilic portion. Included in both calculations are polymerized units containing hydroxyl groups. The unit other than the polymerized unit based on the fluoroolefin and the polymerized unit based on the macromonomer having a hydrophilic moiety is preferably 0 to 70 mol%. If the amount of this unit is too large, the weather resistance deteriorates, which is not preferable.

The aqueous dispersion of the present invention is a dispersion of the above fluorocopolymer in water. Further, the aqueous dispersion of the present invention exhibits excellent mechanical and chemical stability even in the absence of an emulsifier or a hydrophilic organic solvent which is usually used in a fluoropolymer aqueous dispersion. Of course, either one or both of the emulsifier and the hydrophilic organic solvent may be added. However, it is preferable that the hydrophilic organic solvent is not added from the viewpoint of solvent regulation.

When an emulsifier is used, an anionic, cationic, nonionic, amphoteric, nonionic-cationic type, nonionic-anionic type or one having a reactive group is used alone or in combination. be able to. 20% by weight for safety when using hydrophilic organic solvent
The following is preferable.

The aqueous dispersion of the present invention can be produced by emulsion-polymerizing a fluoroolefin, a macromonomer having a hydrophilic moiety and, if necessary, another monomer in an aqueous medium. The initiation of emulsion polymerization is carried out by adding a polymerization initiator in the same manner as the usual initiation of emulsion polymerization.

As such a polymerization initiator, an ordinary radical initiator can be used, but a water-soluble initiator is preferably adopted, and specifically, a persulfate such as ammonium persulfate, hydrogen peroxide or a combination thereof is used. A redox initiator composed of a combination with a reducing agent such as sodium bisulfite and sodium thiosulfate, and an inorganic initiator of a system in which a small amount of iron, ferrous salt, silver sulfate and the like coexist, or disuccinic acid. Examples thereof include dibasic acid peroxides such as peroxides and diglutaric acid peroxides, and organic initiators such as azobisisobutylamidine hydrochloride and azobisbutyronitrile.

The amount of the polymerization initiator used can be appropriately changed depending on the type, emulsion polymerization conditions and the like, but usually 0.005 to 0.5 parts by weight is preferably used per 100 parts by weight of the monomer to be emulsion polymerized. To be done. Further, these polymerization initiators may be added all at once, or may be added in portions if necessary.

For the purpose of raising the pH of the emulsion,
A pH adjuster may be used. Examples of such pH adjusters include inorganic bases such as sodium carbonate, potassium carbonate, sodium orthophosphate, sodium thiosulfate, and sodium tetraborate, and organic bases such as triethylamine, triethanolamine, dimethylethanolamine, diethylethanolamine, and the like. It is illustrated.

The addition amount of the pH adjusting agent is usually an emulsion polymerization medium.
About 0.05 to 2 parts by weight per 100 parts by weight, preferably 0.1
~ 2 parts by weight. The higher the pH, the faster the polymerization rate.

The optimum value of the emulsion polymerization initiation temperature is appropriately selected mainly depending on the type of the polymerization initiator.
A temperature of -100 to 100 ° C, particularly 10 to 90 ° C is preferably adopted. The reaction pressure can be appropriately selected, but is usually 1 to 10
0 kg / cm ^2, in particular it is desirable to employ a to 50 kg / cm ² degree.

In such a production method, additives such as a monomer, a solvent and an initiator may be charged as they are and polymerized as they are, but the particle size of the dispersed particles may be reduced to stabilize the dispersion liquid and the gloss of the coating film. For the purpose of improving various physical properties such as, a pre-emulsification may be performed by using a stirrer such as a homogenizer before adding the polymerization initiator, and then the initiator may be dropped to perform polymerization. Further, the monomers may be added in a divided manner or continuously, in which case the monomer composition may be different.

The aqueous dispersion of the present invention can be used as an aqueous coating as it is, but if necessary, 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 colorant include dyes, organic pigments and inorganic pigments. Examples of the plasticizer include conventionally known ones, for example, low molecular weight plasticizers such as dimethyl phthalate and dioctyl phthalate, high molecular weight plasticizers such as vinyl polymer plasticizers and polyester plasticizers.

Examples of the curing agent include blocked isocyanates such as hexamethylene isocyanate trimer or emulsion dispersions thereof, melamine resins such as methylated melamine, methylolated melamine and butyrolated melamine, methylated urea and butylated urea. Urea resin etc. can be mentioned. A pH adjuster may be added to improve the stability of the aqueous dispersion.

[0053]

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

EXAMPLE An ethyl vinyl ether (EV) having the composition shown in Table 1 was placed in a stainless steel autoclave equipped with a stirrer having an internal volume of 200 ml.
E), cyclohexyl vinyl ether (CHVE), hydroxybutyl vinyl ether (HBVE), macromonomer having hydrophilic site (EOVE-1 or EOV)
E-2), ion-exchanged water, ammonium perfluorooctanoate (initiator), potassium carbonate (K ₂ CO ₃ ), sodium bisulfite (NaHSO ₃ ), ammonium persulfate (APS) were charged and cooled with ice, Nitrogen gas 3.
Depressurize by pressurizing to 5kg / cm ² . This pressure degassing is 2
After repeating the cycle, degasses to 10 mmHg to remove dissolved air, and then add chlorotrifluoroethylene (CTFE) or tetrafluoroethylene (TFE) and perfluoropropyl vinyl ether (PPVE), and react at 30 ° C for 12 hours. It was

The macromonomer having a hydrophilic moiety is a compound represented by the following formula: EOVE-1 has a number average molecular weight of about 700, and EOVE-2 has a number average molecular weight of about 50.
It is 0. CH ₂ = CHOCH ₂ CH ₂ CH ₂ CH ₂ (OCH ₂ CH ₂ ) _n OH

71 parts of the aqueous dispersion obtained above, 1.8 parts of a film-forming aid, 0.3 part of a thickener, 15.4 parts of a pigment, 0.8 part of a dispersant, 0.6 part of a defoaming agent. Parts and 10.3 parts of pure water were used to formulate the paint. The film-forming auxiliary is Texanol Cs-12 (manufactured by Chisso), the thickener is Reobis CR (manufactured by Hoechst Synthetic), and the pigment is titanium oxide (CR-manufactured by Ishihara Sangyo).
90), the dispersant is Disrol-H-14N (manufactured by Nippon Emulsifier), and the antifoaming agent is FS Antifoam 013B (manufactured by Dow Corning).

[0057]

[Table 1]

The above paint was applied to an aluminum plate using a fill applicator so that the dry film thickness would be 40 μm.
It dried at 60 degreeC for 20 hours, and obtained the test piece. The test piece was tested for stain resistance and water repellency. In addition,
In the stain resistance test, the color difference (ΔE) from the initial value was measured by outdoor exposure in Kawasaki City using a color difference meter. The values in the lower row are the values after washing (wiping with gauze soaked in water until dirt does not adhere to the gauze). The water repellency test measured the contact angle (deg) of water.

[0059]

[Table 2]

[0060]

INDUSTRIAL APPLICABILITY The aqueous dispersion of the present invention is extremely useful as a paint base having excellent stain resistance and water repellency, and a coating film obtained by the aqueous paint composition of the present invention has weather resistance, It has the advantage of excellent stain resistance.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location C08F 299/02 MRR 7442-4J C08L 29/10 LGZ 6904-4J C09D 127/12 PFG 9166-4J 129 / 10 PFP 6904-4J

Claims (2)

[Claims] 1. A fluorine-containing copolymer having as essential constituents 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 perfluoroalkyl vinyl ether is dispersed in water. Aqueous dispersion. 2. The fluorine-containing copolymer comprises 20 to 80 mol% of a polymer unit based on a fluoroolefin, and 0.1 to a polymer unit based on a macromonomer having a hydrophilic site.
The aqueous dispersion according to claim 1, which is a polymer containing 25 mol% and a polymerized unit based on perfluoroalkyl vinyl ether in a proportion of 1 to 50 mol%.