JPH0762289A - Aqueous fluorine-containing resin coating - Google Patents

Abstract

PURPOSE:To provide an aqueous resin coating capable of being preferably used as an one pack type ordinary temperature drying type aqueous coating and giving coating films high in gloss and excellent in stain resistance and weather resistance. CONSTITUTION:An aqueous fluorine-containing resin coating comprises a fluorine-containing resin which is dispersed in an aqueous medium, and is produced by emulsion-polymerizing (a) a fluoroolefin, (b) the vinyl ester of a 3-6C linear aliphatic carboxylic acid, (c) the vinyl ester of a 4-15C branched aliphatic carboxylic acid, (d) an ethylenically unsaturated monomer having a hydrophilic functional group, and (e) other copolymerization monomers at a ratio of 30-60mol.%, 5-20mol.%, 20-45mol.%, 0.01-5mol.% and 0-30mol.%, respectively, and having a number-average mol.wt. of 50,000-1,000,000.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-based fluorine-containing resin coating material. The coating material of the present invention has excellent stain resistance and weather resistance, and can be used as a one-part room temperature dry type coating material. It is particularly suitable for on-site coating of building materials and exteriors such as automobiles.

[0002]

2. Description of the Related Art In the field of paints, a fluorine-containing resin paint having excellent weather resistance has been attracting attention, and a fluorine-containing copolymer composed of chlorotrifluoroethylene, cyclohexyl vinyl ether and alkyl vinyl ether and hydroxyalkyl vinyl ether (Japanese Laid-Open Patent Application No. 57-34107), or a fluorinated copolymer composed of chlorotrifluoroethylene, an aliphatic vinyl ester and a hydroxyl group-containing allyl ether (Japanese Patent Laid-Open No. 61-57609), and the like for organic solvent-based paints. Fluorine-containing copolymers have been proposed. According to the organic solvent type fluorine-containing resin coating material, a high-gloss coating film can be obtained and coating and curing are easy, but in the point of using a large amount of organic solvent, it is harmful to human body and environmental pollution. There is a problem, and a water-based fluororesin paint is required.

Several proposals have already been made for water-based fluororesin paints. For example, JP-A-2-225550 discloses a copolymer containing a fluoroolefin, a polyoxyethylene group-containing macromonomer and a hydroxyl group-containing monomer. A coalescent aqueous dispersion is disclosed. However, although it is common throughout the coating technology field, it is not easy to obtain a coating film having excellent physical properties on the same level as an organic solvent-based coating material with an aqueous coating material. Under the present circumstances, an aqueous fluororesin coating material having practically satisfactory physical properties such as insufficient hardness of the coating film obtained has not yet been obtained.

[0004]

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventors obtained an aqueous resin dispersion excellent in dispersion stability by emulsion polymerization of the following monomer mixture. That the dispersion can provide a coating film having practically sufficient mechanical strength without using a crosslinking agent, and the coating film can be compared with a conventional water-based fluororesin coating material. The inventors have found that the gloss and stain resistance are more excellent, and have completed the present invention.

That is, the present invention provides (a) a fluoroolefin, (b) a vinyl ester of a linear aliphatic carboxylic acid having 3 to 6 carbon atoms, and (c) a branched aliphatic carboxylic acid having 4 to 15 carbon atoms. Fluorine-containing resin obtained by emulsion polymerization of vinyl ester of carboxylic acid, (d) ethylenically unsaturated monomer having hydrophilic functional group and (e) other copolymerizable monomer is dispersed in an aqueous medium, The fluorine-containing resin has a number average molecular weight of 50,000 to 1,000,000, and (a)
The proportion of the monomer units of (e) to (e) is (a); 30 to 60 mol%, and (b); 5 based on the total amount of all the monomer units.
~ 20 mol%, (c); 20-45 mol%, (d);
It is an aqueous fluororesin coating material in which 0 to 5 mol% and (e); 0 to 30 mol%.

The present invention will be described in more detail below. Examples of the fluoroolefin used in the present invention include chlorotrifluoroethylene, tetrafluoroethylene and hexafluoropropylene.
Chlorotrifluoroethylene is preferable in terms of easy handling.

Examples of the vinyl ester of a straight-chain aliphatic carboxylic acid having 3 to 6 carbon atoms as the component (b) include vinyl propionate, vinyl butyrate, vinyl heptanoate and vinyl caproate. With a linear aliphatic carboxylic acid vinyl ester having 7 or more carbon atoms, the resulting fluororesin has poor stain resistance, and with vinyl acetate, the resulting fluororesin has poor weather resistance. In the present invention, by using the specific linear carboxylic acid vinyl ester and the component (c) together in a specific ratio, a fluororesin coating material having excellent film-forming property and stain resistance can be obtained.

Examples of the vinyl ester of branched aliphatic carboxylic acid having 4 to 15 carbon atoms, which is the component (c), include vinyl isobutyrate, vinyl pivalate, vinyl 2-ethylhexanoate, and branched carbon atoms having 9 carbon atoms. Examples thereof include vinyl ester of versatic acid (mixture of geometrical isomers) which is a carboxylic acid and vinyl ester of versatic acid which is a branched carboxylic acid having 10 carbon atoms. From the viewpoint of high glass transition temperature of the obtained fluororesin, vinyl pivalate and vinyl ester of versatic acid having 9 carbon atoms are preferable.

The (d) component ethylenically unsaturated monomer having a hydrophilic functional group is an ethylenically unsaturated monomer having a hydrophilic functional group such as a carboxyl group or a salt thereof, a sulfone group or a salt thereof, a hydroxyl group and an amino group. It is a saturated monomer. The ethylenically unsaturated monomer having a carboxyl group,
Acrylic acid, methacrylic acid, crotonic acid, itaconic acid,
Maleic acid, fumaric acid, vinyl acetic acid and the like,
Examples of the monomer having a sulfonic group include vinyl sulfonic acid, styrene sulfonic acid, allyl sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid and the like. The salt of the above monomer is preferably a salt of ammonia, amine or alkali metal.

Examples of the hydroxyl group-containing monomer include hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, hydroxybutyl vinyl ether, hydroxyethyl allyl ether, hydroxyethyl crotonate and N-methylol. Examples include acrylamide. Examples of the monomer having an amino group include methacrylamide, acrylamide, diethylaminoethyl methacrylate, dimethylaminoethyl acrylate and aminopropyl vinyl ether.

The preferred monomer as the component (d) is a monomer having a carboxyl group or a salt thereof and a monomer having a sulfone group or a salt thereof, and specifically, acrylic acid, methacrylic acid, 2 -Acrylamido-2-methylpropanesulfonic acid and salts thereof.

The component (e) in the present invention is the above (a).
To (d) are copolymerizable monomers other than the component, and can be used as desired. Such other monomers include ethylene, propylene, isobutylene, styrene,
Examples thereof include vinylidene fluoride, vinyl fluoride, vinylidene chloride, vinyl chloride, ethyl vinyl ether, butyl vinyl ether, methyl (meth) acrylate, cyclohexyl (meth) acrylate, allyl acetate, allyl butyrate and ethyl allyl ether.

The ratio of each monomer unit in the fluororesin obtained by copolymerizing the above-mentioned monomers is, as described above, based on the total amount of all monomer units, the fluoroolefin monomer unit. 30-60 mol%, vinyl ester of linear aliphatic carboxylic acid having 3 to 6 carbon atoms (hereinafter referred to as linear vinyl carboxylate) monomer unit; 5 to 20 mol%, and 4 to 4 carbon atoms 15 branched aliphatic carboxylic acid vinyl ester (hereinafter referred to as branched vinyl carboxylate) monomer units; 20 to 45 mol%, an ethylenically unsaturated monomer having a hydrophilic functional group (hereinafter referred to as a hydrophilic monomer) Unit); 0.0
1 to 5 mol% and other copolymerizable monomer units; 0 to
It is 30 mol%.

The proportion of fluoroolefin monomer units is
When it exceeds 60 mol%, the dispersion stability of the obtained fluororesin aqueous dispersion is poor, and when it is less than 40 mol%, the weather resistance of the coating composition is poor. If the proportion of the linear vinyl carboxylate monomer units exceeds 20 mol%, the stain resistance of the coating film obtained by the obtained coating composition is poor, and if it is less than 5 mol%, the flexibility of the coating film is poor. If the proportion of the branched vinyl carboxylate monomer units exceeds 45 mol%, the film-forming property during coating will be poor, while if it is less than 20 mol%, the stain resistance of the coating film will be poor. If the proportion of the hydrophilic monomer units exceeds 5 mol%, the water resistance of the coating film will be poor, while if it is less than 0.01 mol%, the dispersion stability of the resin dispersion will be poor.

More preferably, fluoroolefin monomer units; 40 to 55 mol%, linear vinyl carboxylate monomer units; 7 to 15 mol%, branched vinyl carboxylate monomer units; 30 to 40 Mol%, hydrophilic monomer unit; 0.1
~ 3 mol% and other copolymerizable monomer units; 0-2
It is 0 mol%.

The glass transition temperature of the fluororesin in the present invention is preferably 30 to 100 ° C, more preferably 45 to 100 ° C. If the glass transition temperature of the fluororesin is less than 30 ° C, the coating film will be softened at high temperatures in the summer and pollutants will easily adhere, while 100 ° C.
If it exceeds, cracks are likely to occur in the coating film.

The molecular weight of the fluorine-containing resin is, in terms of polystyrene equivalent number average molecular weight by gel permeation chromatography, 50,000 to 1,000,000, and more preferably 100,000 to 1,000,000. When the number average molecular weight of the fluorine-containing resin is less than 50,000, the coating film is inferior in mechanical strength, while when it exceeds 1,000,000, the coating film obtained is inferior in film forming property.

The aqueous fluororesin dispersion of the present invention can be obtained by emulsion polymerization of the above-mentioned monomers in an aqueous medium in the presence of an emulsifier. The resin content concentration in the aqueous dispersion is preferably 30 to 60% by weight.

As the emulsifier, an anionic emulsifier and a nonionic emulsifier are preferably used in combination, and the preferable amount thereof is 0.5 to 5 parts by weight of the anionic emulsifier per 100 parts by weight of the total amount of the charged monomers. The amount of the nonionic emulsifier is 2 to 8 parts by weight. If the amount of emulsifier used exceeds the above amount, the water resistance of the resulting coating film tends to decrease. From the viewpoint of water resistance, the smaller the amount of the emulsifier used, the more preferable.

The anionic emulsifier is preferably a fluorine-based anionic emulsifier such as perfluorooctanoic acid potassium salt or its ammonium salt, and perfluorooctanesulfonic acid sodium salt or its ammonium salt, but ammonium lauryl sulfate and dodecylbenzene sulfone are preferable. Sodium acid, sodium alkylnaphthalene sulfonate, sodium dialkyl sulfosuccinate, sodium polyoxyethylene alkyl ether sulfate, sodium alkane sulfonate and the like can also be used.

As the nonionic emulsifier, polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester,
Examples thereof include glycerin fatty acid ester and polyoxyethylene fatty acid ester, and polyoxyethylene alkyl ether and polyoxyethylene alkyl phenyl ether are preferable.

The polymerization initiator is preferably a radical-generating type polymerization initiator, and specifically, diisopropyl peroxydicarbonate, tertiary butyl peroxypivalate, benzoyl peroxide, lauroyl peroxide and succinic acid peroxide. And the like; azo compounds such as azobisisobutyronitrile, azobisisovaleronitrile and azobisamidinopropane hydrochloride; inorganic peroxides such as ammonium persulfate and potassium persulfate. A redox type initiator may be used, in which case, together with the above-mentioned peroxide, sodium bisulfite, sodium sulfite,
Use a reducing agent such as Rongalit or ascorbic acid. The preferred amount of the polymerization initiator used is 0.1 to 2 parts by weight per 100 parts by weight of the total amount of the charged monomers. When the amount of the polymerization initiator used exceeds 2 parts by weight, the molecular weight of the resulting fluororesin becomes low, and the mechanical strength of the coating film tends to be insufficient.

The polymerization operation uses a pressure resistant autoclave,
It can be carried out at a temperature of 20 to 100 ° C. and a pressure of 1 to 200 kg / cm ² , and the polymerization time is suitably 3 to 40 hours. As a method of charging each of the monomers into the polymerization vessel, all the monomers may be initially charged in the total amount, or a part of the monomers may be sequentially added as the polymerization proceeds. In addition, it is preferable that the monomers that are sequentially added are emulsified with an emulsifier. Furthermore, it is preferable to adjust the PH of the polymerization system to 6 to 8 by adding a pH adjusting agent such as potassium carbonate, sodium hydrogen carbonate and disodium phosphate to the polymerization system.

The aqueous dispersion of the fluorine-containing resin synthesized by the above method is made into a paint by adding a film forming aid such as butyl cellosolve acetate. A pigment, a metal powder and various paint additives can be added to the resulting water-based fluororesin paint. Preferable pigments include titanium oxide, iron oxide, phthalocyanine blue, benzidine yellow, quinacridone and the like, and metal powders include stainless powder, aluminum powder and bronze powder. Other additives include pigment dispersants, ultraviolet absorbers, surface modifiers, thickeners, fungicides and rust preventives.

The aqueous fluororesin coating material of the present invention can be suitably applied to a base material such as steel plate, stainless steel, aluminum, concrete, mortar, plastic and wood. The coating method is spray, brush, roll or bar coater. Either can be adopted. Hereinafter, the present invention will be described more specifically with reference to examples.

[0026]

【Example】

<Example 1> 206 g of pure water and the following emulsifier were charged into a 1-liter autoclave equipped with a stirrer. Anionic emulsifier; perfluorooctanoic acid ammonium salt (anionic emulsifier) 6.4 g Nonionic emulsifier; Emulgen 910 manufactured by Kao Corporation 1
0.9 g and 10.9 g of Emulgen 930 manufactured by the same (Emulgen 910 and 930 both belong to polyoxyethylene nonylphenyl ether)

Next, 25 g of vinyl caproate (hereinafter referred to as VCp), 98 g of versatic acid vinyl ester (having a branched alkyl group having 8 carbon atoms) (hereinafter referred to as V-9), 2-acrylamido-2- After 1.6 g of methylpropanesulfonic acid (hereinafter referred to as ATBS) and 2.7 g of sodium hydrogen carbonate were charged, deaeration and nitrogen substitution were repeated 3 times, and then 170 g of chlorotrifluoroethylene (hereinafter referred to as CTFE) was charged. After heating to 40 ° C, thoroughly stir for 1 hour to obtain 1.2 g of ammonium persulfate.
And a polymerization initiator consisting of 0.23 g of sodium bisulfite was injected under pressure to initiate the polymerization. Then, every 3 hours, a half amount of the above polymerization initiator was added, and the polymerization was continued for 10 hours, whereby the resin content concentration was 49% by weight and the average particle diameter of the resin content was 0.33μ. An aqueous dispersion of a fluororesin was obtained.

The dispersion stability of the above aqueous dispersion was measured according to the method specified in JIS K5663. a. Mechanical stability: 100 g of the dispersion was stirred with a homodisper at 5000 rpm for 5 minutes, and the amount of aggregation (unit: ppm) after standing for 1 day was measured. b. High temperature stability: The dispersion was allowed to stand at 50 ° C. and the number of days until aggregation started was measured. As a result, the mechanical stability was 90 ppm and the high temperature stability was 6 days.

The results of elemental analysis of fluorine atoms of the fluororesin isolated by pouring a part of the above resin dispersion into methanol, washing and drying it are as follows.
It was 19.4% by weight, and from this value and the measurement results of ¹ H-NMR and ¹³ C-NMR spectra, the composition of the fluorine-containing resin was CTFE / VCp / V-9 / ATBS = 4.
It was found to be 9/12/38/1 (mol%).
The number average molecular weight of the fluororesin was 120,000, and the glass transition temperature was 51 ° C.

5 parts by weight of butyl cellosolve acetate was added as a film forming aid to 100 parts by weight of the above aqueous dispersion, and the physical properties of the obtained aqueous coating material were evaluated by the following methods. The above coating composition was applied onto a chromate-treated electrogalvanized steel sheet having a thickness of 0.6 mm by a bar coater so that the thickness of the coating film after drying was 30 μm, and dried at room temperature for 1 week.
The obtained coating film was evaluated for the following items. The results are as shown in Table 1 below.

60 ° gloss: By a method according to JIS-K5400. Weather resistance: Using a fluorescent UV weather resistance tester (generally abbreviated as QUV) manufactured by Q-Panel, continuously irradiate with ultraviolet rays for 8 hours, and then spray ion-exchanged water from the back side of the coated surface for 4 hours. Repeat the cycle for a total of 5
It was evaluated by the 60 ° gloss retention after the 00 hour test. Contamination test: The degree of contamination after the operation of applying an artificial soiling agent consisting of the following components to the surface of the coating film and then washing the surface of the coating film with water five times was evaluated as the color difference (ΔE) before and after this test. ) Evaluated. 〇 Artificial soiling agent (component) (parts by weight) Leaf soil 7.6 Kaolin 3.4 Diatomaceous earth 3.4 Cement 3.4 Carbon black 0.35 Red rust 0.10 Oil 1.75 Sea sand 200

<Example 2> CTFE / V was used as a monomer.
Polymerization was carried out in the same manner as in Example 1 except that a monomer mixture having a composition of −9 / vinyl propionate (hereinafter referred to as VPr) / methacrylic acid = 170 g / 98 g / 18 g / 1.6 g was used to obtain a solid content. An aqueous dispersion of a fluororesin having a concentration of 48% by weight was obtained. The average particle size of the resin particles in the dispersion was 0.46μ. The fluorine-containing resin forming the resin particles had a number average molecular weight of 200,000 and a glass transition temperature of 59 ° C. The fluorine analysis value of this fluorine-containing resin is 20.1%, and CTFE / V-9 / VPr / methacrylic acid = 50/37/12/1 (mol%) by the same analysis as in Example 1. I understood.

The dispersion stability of the above aqueous dispersion was measured by the same method as in Example 1, and it was found that the mechanical stability was 1
At 20 ppm, high temperature stability was 4 days. Table 1 shows the evaluation results of the physical properties of the aqueous paint obtained by adding butyl cellosolve acetate to the above aqueous dispersion.

<Example 3> CTFE / V was used as a monomer.
-9 / VCp / vinyl laurate (hereinafter referred to as VL) /
Acrylic acid = 173g / 93g / 24g / 6.2g / 1.8
Polymerization was performed in the same manner as in Example 1 except that g of the monomer mixture was used to obtain an aqueous fluororesin dispersion having a solid content concentration of 48% by weight. The average particle size of the resin particles in the dispersion was 0.61μ. The fluorine-containing resin had a number average molecular weight of 80,000 and a glass transition temperature of 42 ° C. The fluorine analysis value of this fluorine-containing resin was 20.1%, and when analyzed in the same manner as in Example 1, CTFE / V-
9 / VCp / VL / acrylic acid = 49/36/11/2
It was found to be / 1 (mol%).

Regarding the dispersion stability of the above aqueous dispersion,
The mechanical stability was 70 ppm and the high temperature stability was 7 days. Table 1 shows the evaluation results of the aqueous paint obtained from the above aqueous dispersion.

<Example 4> CTFE / vinyl pivalate (hereinafter referred to as VPv) / VCp / methyl acrylate (hereinafter referred to as MA) / ATBS = 170 g / as a monomer
Polymerization was performed in the same manner as in Example 1 except that 65 g / 15/5 g / 0.8 g of the monomer mixture was used to obtain a fluororesin aqueous dispersion having a solid content concentration of 45% by weight.
The average particle size of the resin particles in the dispersion was 0.41μ. The fluorine-containing resin had a number average molecular weight of 110,000 and a glass transition temperature of 53 ° C. The fluorine analysis value of this fluorine-containing resin was 24.0%, and when analyzed in the same manner as in Example 1, CTFE / VPv / VCp / MA / AT
It was found that BS = 51/37/8/3/1 (mol%).

Regarding the dispersion stability of the above aqueous dispersion,
The mechanical stability was 250 ppm, the high temperature stability was 4 days, and the evaluation results of the physical properties of the obtained aqueous coating material are shown in Table 1.

Comparative Example 1 CTFE / V was used as a monomer.
Cp / V-9 / ATBS is 170 g / 93 g / 13 g /
Polymerization was carried out in the same manner as in Example 1 except that 1.0 g of the monomer mixture was used to obtain an aqueous fluororesin dispersion having a solid content concentration of 45% by weight. The average particle size of the resin particles in the dispersion was 0.88μ. The fluorine-containing resin has a number average molecular weight of 140,000 and a glass transition temperature of 8.
It was 6 ° C. The fluorine analysis value of this fluorine-containing resin is 18.
8%, and CTFE when analyzed in the same manner as in Example 1.
/VCp/V-9/ATBS=44/49.5/6/0.5
It was found to be (mol%).

Regarding the dispersion stability of the above aqueous dispersion,
The mechanical stability was 1000 ppm and the high temperature stability was within 1 day. The evaluation results of the physical properties of the obtained water-based paint are as shown in Table 1.

[0040]

[Table 1]

[0041]

INDUSTRIAL APPLICABILITY The fluorine-containing resin of the present invention has a sufficiently large molecular weight and forms a coating film excellent in mechanical strength without cross-linking, and is therefore suitable as a one-component room temperature drying type aqueous coating resin. In addition, the coating film has the features of high gloss and excellent stain resistance and weather resistance.

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] November 16, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0027

[Correction method] Change

[Correction content]

Next, 25 g of vinyl caproate (hereinafter referred to as VCp) and vinyl ester of versatic acid (having a carbon number of
Nine branched carboxylic acid vinyl esters ) (hereinafter V-
9), 2-acrylamido-2-methylpropanesulfonic acid (hereinafter referred to as ATBS) 1.6 g, and sodium hydrogencarbonate 2.7 g were charged, and after deaeration and nitrogen replacement were repeated 3 times, chlorotrifluoro 170 g of ethylene (hereinafter referred to as CTFE) was charged. After heating to 40 ° C, stir thoroughly for 1 hour to remove ammonium persulfate.
A polymerization initiator consisting of 1.2 g and sodium bisulfite 0.23 g was injected under pressure to initiate the polymerization. Then, every 3 hours, a half amount of the above polymerization initiator was added, and the polymerization was continued for 10 hours, whereby the resin content concentration was 49% by weight and the average particle diameter of the resin content was 0.33μ. An aqueous dispersion of a fluororesin was obtained.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Ryusei Nishio 1 1 Funami-cho, Minato-ku, Nagoya-shi, Aichi Toagosei Chemical Industry Co., Ltd. Nagoya Research Institute (72) Inventor Akito Iida Nagoya, Aichi 1 Toago Synthetic Chemical Industry Co., Ltd., Nagoya Research Institute, Minami-ku, Toagosei Chemical Industry Co., Ltd. (72) Inventor Hiroshi Inukai 1 Touna Synthetic Chemical Industry Co., Ltd. Nagoya Research Laboratories, 1 Funami-cho, Minato-ku, Aichi Within

Claims (1)

[Claims] 1. A fluoroolefin (a), (b) a vinyl ester of a linear aliphatic carboxylic acid having 3 to 6 carbon atoms, and (c) a vinyl ester of a branched aliphatic carboxylic acid having 4 to 15 carbon atoms. A fluororesin obtained by emulsion polymerization of an ester, (d) an ethylenically unsaturated monomer having a hydrophilic functional group, and (e) another copolymerizable monomer is dispersed in an aqueous medium. Has a number average molecular weight of 50,000 to 1,0
0,000, and the ratio of the monomer units (a) to (e) is based on the total amount of all monomer units,
(A); 30 to 60 mol%, (b); 5 to 20 mol%,
(C); 20 to 45 mol%, (d); 0.01 to 5 mol%
And (e): 0 to 30 mol% of an aqueous fluororesin coating material.