JPH06248224A - Fluororesin coating composition - Google Patents

Abstract

PURPOSE:To provide a coating composition as a coating of excellent weatherability and chemical resistance, comprising a fluorocopolymer produced by copolymerization of specific kinds of monomers, an ultraviolet light absorber, a light stabilizer, an organic solvent and a cross-linking agent. CONSTITUTION:The composition comprising (A) a fluorocopolymer produced by copolymerization among (1) 40-60mol% fluororesin monomer (pref. chlorotrifluoroethylene), (2) 3-30mol% hydroxyalkyl crotonate monomer (pref. 2-hydroxyethyl crotonate) and (3) 10-67mol% another copolymerizable vinyl monomer (e.g. carboxylic vinyl ester), (B) an ultraviolet light absorber (e.g. benzophenone-based compound) and a light stabilizer (e.g. hindered amine-based compound), (C) an organic solvent (e.g. toluene) and (D) a cross-linking agent reactive with hydroxyl group (e.g. hexamethylene diisocyanate).

Description

Detailed Description of the Invention

[0001]

This invention relates to a fluorine-containing copolymer,
The present invention relates to an organic solvent type fluororesin coating composition containing an ultraviolet absorber and / or a light stabilizer and a crosslinking agent.

[0002]

2. Description of the Related Art As a paint having excellent weather resistance and chemical resistance, a fluororesin paint comprising a fluorine-containing copolymer and a curing agent has been conventionally known. On the other hand, the inventors of the present invention researched and developed a fluororesin coating material having excellent adhesion to substrates such as plastics, cement and mortar, and made the inventions of JP-A-3-231906 and Japanese Patent Application No. 3-146860. Proposed.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
The fluororesin paints proposed in Japanese Patent Application No. 906 and Japanese Patent Application No. 3-146860 are applied as a clear paint or a color clear paint having a low pigment concentration to a base material such as plastic, cement, mortar, etc. In the case of forming a color clear coating film having a low pigment concentration, the undercoat protection property for a long period of time was not always sufficient as compared with a coating film having a high pigment concentration. That is, there is a problem that the deterioration of the substrate due to sunlight rays that penetrate the coating film and reach the substrate cannot be sufficiently suppressed. Specifically, the substrate gradually deteriorates, and in the case of a metal substrate, rust is generated. And the deterioration of the undercoat paint was observed on concrete-based substrates such as cement and mortar.

In view of the above circumstances, the present invention is a fluororesin coating composition capable of maintaining the undercoat protection property for a long period of time even when forming a clear coating film or a color clear coating film having a low pigment concentration. The purpose is to provide goods.

[0005]

The fluororesin coating composition of the present invention comprises (1) a) a fluoroolefin monomer unit: 30 to 60
Mol% b) hydroxyalkyl crotonic acid monomer unit: 3 to 3
0 mol% c) Copolymerizable vinyl monomer units other than the above: 10
Fluorine-containing copolymer composed of 67 mol% (2) UV absorber and / or light stabilizer (3) Organic solvent and (4) Crosslinking agent capable of reacting with hydroxyl group To do.

In the present invention, the fluorine-containing copolymer represented by the above (1) is obtained by the inventor of the above-mentioned JP-A-3-
The fluorine-containing copolymer disclosed in No. 231906 is specifically composed of a fluoroolefin monomer, a hydroxyalkyl crotonic acid monomer and a copolymerizable vinyl monomer other than the above. The a) fluoroolefin monomer constituting the fluorine-containing copolymer is specifically monofluoroethylene, difluoroethylene, trifluoroethylene, tetrafluoroethylene, chlorotrifluoroethylene, hexafluoropropylene, or the like. Among them, chlorotrifluoroethylene can be preferably used in terms of easy copolymerizability and handling. Such a fluoroolefin monomer is contained in a proportion of 30 to 6 with respect to the total monomers constituting the fluorocopolymer.
It is contained in the range of 0 mol%, and when it is less than 30 mol%, the weather resistance of the fluororesin composition as a coating is lowered,
When the amount is more than 0 mol%, the solubility in the solvent decreases, so a more preferable amount is 40 to 60 mol%.

The hydroxyalkyl crotonic acid monomer b) constituting the fluorine-containing copolymer is specifically 2-hydroxyethyl crotonate, 4-hydroxybutyl crotonate, 2-hydroxypropyl crotonate or the like. Among them, 2-hydroxyethyl crotonate, whose monomer is easily available, is particularly preferably used. This hydroxyalkyl crotonic acid monomer is contained in the range of 3 to 30 mol% as a ratio to all the monomers constituting the fluorocopolymer, and if it is less than 3 mol%, the reaction with the crosslinking agent occurs. If the composition is insufficient, the resulting composition has insufficient coating film strength, and if it is blended in a large amount in excess of 30 mol%, the weather resistance and water resistance will deteriorate.

A fluoroolefin monomer of the above a),
The copolymerizable vinyl monomer of c) to be blended with the hydroxyalkyl crotonic acid monomer of b) is used in the range of 10 to 67 mol% based on all the monomers constituting the fluorine-containing copolymer. As such vinyl monomers, vinyl carboxylates, vinyl ethers, norbornadiene compounds and the like are preferably used.

Examples of the vinyl carboxylate ethers are vinyl propionate, vinyl caproate, vinyl pivalate and Veova-9, Veova-10 (these Veova-9 and 10 are vinyl carboxylates manufactured by Shell Chemical Co., Ltd.). Aliphatic vinyl esters (trade name of ester), vinyl cyclohexanecarboxylate, 4-t
-Vinyl cycloalkanecarboxylates such as vinyl butylcyclohexanecarboxylate, vinyl benzoate, pt-
Examples thereof include aromatic vinyl carboxylates such as butylbenzoic acid.

Examples of vinyl ethers include alkyl vinyl ethers such as ethyl vinyl ether and butyl vinyl ether, and cycloalkyl vinyl ethers such as cyclohexyl vinyl ether, and norbornadiene and its alkyl-substituted compounds can be used as a copolymerization component. it can.

In order to improve the pigment dispersibility, crotonic acid may be introduced into the fluorine-containing copolymer (1),
The amount is 5 mol% or less based on the fluorocopolymer.

The molecular weight of the fluorine-containing copolymer obtained by copolymerizing these monomers a) to c) is such that the number average molecular weight is GP from the viewpoint of the strength of the coating film to be formed and the handleability of the coating material.
The polystyrene conversion of C is preferably 1000 to 100000. Further, the Tg (glass transition point) of the fluorinated copolymer is preferably 10 ° C. or higher so that the formed coating film exhibits blocking resistance.

The fluororesin coating composition of the present invention comprises, in addition to the above-mentioned fluorocopolymer, an ultraviolet absorber and / or a light stabilizer, an organic solvent and a crosslinking agent capable of reacting with a hydroxyl group. , The ultraviolet absorber is 400n
A compound that selectively absorbs light in the ultraviolet region of m or less, and specific examples thereof include a benzophenone compound, a benzotriazole compound, an oxalic acid anilide compound, and the like. Hydroxy-4-methoxybenzophenone, 2-hydroxy-4-
Examples thereof include ethoxybenzophenone, 2-hydroxy-4-butoxybenzophenone and 2,4-dihydroxybenzophenone. Further, as the benzotriazole-based compound, a compound having a structural formula represented by the following [Chemical formula 1] can be used.

[0014]

[Chemical 1]

Examples of the compound represented by the above [Chemical formula 1] include X = H, R ₁ = R ₂ = -C (CH ₃ ) ₂ C ₂ H
_{5, compound, X = H, R 1 =} R 2 = -C (CH 3)
Compound which is a _{2 Ph, X = H, R} 1 = -C 1 2 H 2 5,
A compound wherein R ₂ = Me, X = H, R ₁ = -t-Bu,
With a compound _{R 2 = -C 2 H 4 CO-} (OC 2 H 4) is a ₇ -OH, a mixture of succinic acid diester of the compound,
_{X = H, R 1 = -t} -Bu, R 2 = -C 2 H 4 COOC
₈ H _{1 7, compound, X = Cl, R 1 =} -t-Bu,
And the like R ₂ = -C ₂ H ₄ compound is COOC ₈ H _7.

The oxalic acid anilide compound is N
-(2-ethoxyphenyl) -N '-(4-isododecylphenyl) ethanediamide, N- (2-ethoxyphenyl) -N'-(2-ethylphenyl) ethanediamide, N (2-ethoxy-5-t- Butylphenyl-N '
-(2-Ethylphenyl) ethanediamide or the like can be used.

The amount of the ultraviolet absorber added varies depending on the film thickness of the coating film formed, but is generally 1 to 20% by weight based on the total weight of the fluorine-containing copolymer and the crosslinking agent.
If the amount added is too large, the adhesion to the substrate may be impaired, and bleeding (separation) from the coating film may occur, which is not preferable. A more preferable addition amount is less than 10% by weight, and it is desirable to increase the film thickness when adding more than 10% by weight.

The type of such an ultraviolet absorber is preferably selected according to the base material. For example, when forming a coating film on a cement-based base material, an oxalic acid anilide-based compound that does not have a phenolic hydroxyl group that reacts with an alkali is preferable, and a base material such as a plastic molded body, film, or sheet. A benzophenone-based compound, a benzotriazole-based compound, and an oxalic acid anilide-based compound can be preferably used for forming a coating film for the above, and among them, a benzotriazole-based compound having a wide ultraviolet absorption range is particularly preferable.

Examples of the light stabilizer include hindered amine compounds such as bis (1,2,2,2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-n-butylmalonate. , 6,6-Pentamethyl-4-piperidyl), bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate , 8-acetyl-3-dodecyl-7,7,9,9-tetramethyl-
1,3,8-Triazaspiro (4,5) decane-2,4
-Dione, bis (N-octoxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate and the like can be used.

The amount of such a light stabilizer used is 5 based on the total weight of the above-mentioned fluorocopolymer (1) and crosslinking agent (4).
It is desirable that the content is not more than weight%. When this light stabilizer is used in a large amount, a solution obtained by mixing the fluorine-containing copolymer (1), the ultraviolet absorber and / or the light stabilizer (2) and the organic solvent (3) is colored over time, which is not preferable. . In particular,
This phenomenon becomes remarkable when the fluorinated copolymer (1) has a carboxyl group or when the varnish is acidic. Therefore, as the light stabilizer used when the fluorinated copolymer has a carboxyl group or when the varnish is acidic, a structure of N-OR (R is an alkyl group) in which the basicity of nitrogen is lowered is used. Those having The light stabilizer is preferably used together with the above-mentioned ultraviolet absorber, but it is also possible to use only the light stabilizer. However, in this case, the improvement of the undercoat protection is lower than that of the combined use of both, and therefore the combined use is the most preferable.

The organic solvent for dissolving the fluorinated copolymer preferably has a boiling point of 60 ° C. or higher,
Specifically, toluene, xylene, an aromatic organic solvent such as Solvesso, esters such as ethyl acetate and butyl acetate, ketones such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, alcohols such as n-butanol and i-propanol, A cellosolve system such as methyl cellosolve or n-butyl cellosolve can be used.

The crosslinking agent capable of reacting with the hydroxyl group used in the present invention contributes to the curing of the composition by crosslinking with the hydroxyl group of the hydroxyalkyl crotonic acid monomer constituting the fluorine-containing copolymer. Specifically, hexamethylene diisocyanate, isophorone diisocyanate and their dimers, trimers and polyisocyanates such as blocked isocyanate, methylated melamine,
Examples thereof include butylated melamine, urea resin, and aminoplast such as benzoguanamine. A curing accelerator such as dibutyltin dilaurate or p-toluenesulfonic acid may be used in combination with these crosslinking agents.

The composition for fluororesin coating composition of the present invention comprises the above-mentioned aminoplast such as melamine and guanamine and the above-mentioned crosslinking agent which does not react with hydroxyl group at room temperature such as blocked isocyanate. Fluorine-containing copolymer, ultraviolet absorber and / or light stabilizer,
It can be prepared by mixing the organic solvent and the crosslinking agent at once. However, when using a crosslinking agent that reacts with a hydroxyl group even at room temperature, such as polyisocyanate, the fluorine-containing copolymer, the ultraviolet absorber and / or light stabilizer,
It is necessary to mix the organic solvent in advance, and mix it with a crosslinking agent at the time of coating.

The composition for a fluororesin coating material of the present invention can maintain the undercoat protection property for a long period of time mainly by being applied as a clear coating material. However, a small amount of a coloring pigment is added to such a clear coating material. It can be sufficiently used as a blended color clear paint. As the coloring pigment used in that case, it is possible to use a coloring pigment that is used in ordinary paints, for example, titanium oxide, red iron oxide, phthalocyanine blue, quinacridone red, and inorganic pigments such as yellow iron oxide firing pigment. Organic pigments such as isoindolinone and carbon black can also be used.

The fluororesin coating composition obtained by the present invention may contain additives such as a leveling agent, a color separation preventing agent, an antioxidant and a heat stabilizer in its solution. In addition, a pigment oxidizer may be added when the color pigment used as the color clear paint is dispersed. The ratio of the coating film forming component (fluorine-containing copolymer + ultraviolet absorber + light stabilizer + crosslinking agent) in the fluororesin coating composition thus prepared is in the range of 20 to 70% by weight from the viewpoint of workability. Preferably there is.

The fluororesin coating composition of the present invention is prepared by spray coating, roll coater, brush coating, etc., and is used as a base material made of metal such as stainless steel, aluminum and zinc steel sheet, ABS resin, FRP and Nericarbonate resin. , A hard vinyl chloride resin, a pakelite epoxy resin, an acrylic resin, a base material made of plastic such as polyurethane, wood, paper and mortar, and a cement-based base material such as exposed concrete can be applied.

[0027]

The fluororesin coating composition of the present invention is cleared by blending a fluorine-containing copolymer with an ultraviolet absorber and / or a light stabilizer and a crosslinking agent to form an organic solvent type coating composition. Even when it is used as a paint or a color clear paint having a low pigment concentration, the undercoat can be protected for a long period of time.

[0028]

EXAMPLES The present invention will be described in more detail below with reference to examples, comparative examples and test examples for evaluating the physical properties of coating films of the coating compositions obtained by these examples. Example 1 Consists of chlorotrifluoroethylene / vinyl propionate / vinyl versatate / 2-hydroxyethyl crotonate, the respective ratios being 49/23/18/1.
Fluorine-containing copolymer having 0 (mol%) (Mn = 1300
0, OHV (hydroxyl value) = 53, Tg = 28 ° C.) in a xylene solution (solid content 60% by weight) 10.0 g, and 2-hydroxy-4-methoxybenzophenone 0.14 g (fluorine-containing copolymer) as an ultraviolet absorber. (2 parts by weight with respect to the polymer + crosslinking agent), and 1.05 g of Duranate TPA100 (manufactured by Asahi Kasei) as a crosslinking agent (NCO / OH = 1.0 / 1.
0) and 6.5 g of a 1/1 mixture of xylene / methyl isobutyl ketone (MIBK) as a thinner were mixed to prepare a clear paint.

Example 2 Chlorotrifluoroethylene / vinyl pivalate / vinyl caproate / vinyl versatic acid / crotonic acid 2-
Composed of hydroxyethyl, the ratio of each is 47
Fluorine-containing copolymer (Mn = 11000, OHV = 44, Tg = 23) which is / 3/26/13/11 (mol%).
C) xylene solution (solid content 60% by weight) 10.0 g,
Benzotriazole-based Tinuvin 3 as UV absorber
0.13 g of 84 (manufactured by Ciba-Geigy Co., Ltd.) (2 parts by weight based on the fluorine-containing copolymer + crosslinking agent), and 0.87 g of Duranate TPA100 (manufactured by Asahi Kasei) as a crosslinking agent (NCO /
OH = 1.0 / 1.0), xylene / M as thinner
A clear paint was prepared by mixing 6.0 g of a 1/1 mixture of IBK.

Example 3 10.0 g of the fluorocopolymer solution used in Example 2,
Benzotriazole-based Tinuvin 3 as UV absorber
0.13 g of 84 (manufactured by Ciba-Geigy) (fluorine-containing copolymer + 2 phr of curing agent), Tinuvin 12 as a light stabilizer
0.07 g of 3 (manufactured by Ciba-Geigy) (1 part by weight based on fluorine-containing copolymer + crosslinking agent), and 0.87 g (NCO / OH) of Duranate TPA100 (manufactured by Asahi Kasei) as a crosslinking agent.
= 1.0 / 1.0), xylene / MIB as thinner
A clear paint was prepared by mixing 5.4 g of a 1/1 mixture of K.

Example 4 10.0 g of the fluorocopolymer solution used in Example 2,
Sundubiore S, an oxalic acid anilide-based UV absorber
-3206 (manufactured by Sand Co.) 0.13 g (fluorine-containing copolymer + 2 parts by weight based on the curing agent), and Tinuvin 123 (manufactured by Ciba-Geigy) 0.07 g (fluorine-containing copolymer + crosslinking) as a light stabilizer. 1 part by weight to the agent), and 0.87 g (NCO / Duranate TPA100 (manufactured by Asahi Kasei)) as a crosslinking agent.
OH = 1.0 / 1.0), xylene / M as thinner
A clear paint was prepared by mixing 6.2 g of a 1/1 mixture of IBK.

Example 5 10.0 g of the fluorocopolymer solution used in Example 2,
Benzotriazole-based Tinuvin 3 as UV absorber
0.07 g of 84 (manufactured by Ciba-Geigy) (1 part by weight with respect to fluorine-containing copolymer + curing agent), and Tinuvin 123 (manufactured by Ciba-Gigi) 0.035 g (fluorine-containing copolymer + crosslinking) as a light stabilizer. 0.5 part by weight of the agent), and 0.87 g of Duranate TPA100 (manufactured by Asahi Kasei) as a crosslinking agent (NC
O / OH = 1.0 / 1.0) and 6.2 g of a 1/1 mixture of xylene / MIBK as a thinner were mixed to prepare a clear paint.

Comparative Example 1 Fluorine-containing copolymer solution 10.0 used in Example 1 above
1.05 g (NCO / OH = 1.0 / 1.0) of Duranate TPA100 (manufactured by Asahi Kasei) as a crosslinking agent,
Xylene / MIBK 1/1 mixture as thinner 6.
6 g were mixed to prepare a clear paint containing no ultraviolet absorber and no light stabilizer.

Comparative Example 2 Fluorine-containing copolymer solution 10.0 used in Example 2 above
g, 0.87 g (NCO / OH = 1.0 / 1.0) of Duranate TPA100 (manufactured by Asahi Kasei) as a crosslinking agent,
As a thinner, 6.3 g of a 1/1 mixture of xylene / MIBK was mixed to prepare a clear paint containing no ultraviolet absorber and no light stabilizer.

Comparative Example 3 In place of the fluorine-containing copolymer of the present invention, 10.0 g of acrylic resin for coating, Acridic 56-719 (manufactured by Dainippon Ink) (solid content 50 wt%, OHV80),
Benzotriazole-based Tinuvin 3 as UV absorber
0.13 g of 84 (manufactured by Ciba-Geigy) (2 parts by weight with respect to the fluorine-containing copolymer + crosslinking agent), and 0.06 g of Tinuvin 123 (manufactured by Ciba-Gigi) as a light stabilizer (fluorine-containing copolymer + 1 part by weight based on the cross-linking agent), 1.32 g (NCO / Duranate TPA100 (manufactured by Asahi Kasei)) as the cross-linking agent.
OH = 1.0 / 1.0), xylene / M as thinner
A clear paint was prepared by mixing 4.0 g of a 1/1 mixture of IBK.

Test Example 1 A white acrylic urethane coating film (thickness: 30 μm) was formed on an aluminum plate (0.6 mm thickness), and the coating material obtained in Examples 1 to 5 and Comparative Examples 1 to 3 was formed thereon. Each of the compositions was applied as a top coat by a bar coater and left standing at room temperature for 1 week to cure (dry film thickness 10 μm), and the physical properties of the obtained coating film were evaluated by the following physical property evaluation tests. 1) Initial adhesion Shows the residual rate in a cross-cut peeling test according to JIS-K5400. 2) Accelerated weather resistance QUV accelerated weather resistance test (B lamp) Test conditions Irradiation: 63 ° C, 50% RH x 4 hours Condensation: 50 ° C ,> 98% RH × 4 hours, after repeating for 4000 hours, the 60 ° gloss retention and ΔE value are shown. For the accelerated weather resistance test, a coated plate without top clear was added as a blank. 3) Secondary adhesion The residual rate of cross-cut peeling after the QUV accelerated weathering test of the previous item is shown. The results are shown in Table 1. [Margins below]

[0037]

[Table 1]

Test Example 2 Using the clear paint prepared in Example 2, a 20 μm coating film was prepared on stainless steel (SUS304) whose surface was degreased. The SUS plate was used for the same coating film evaluation test as in Test Example 1. The results are shown below. Initial adhesion: 100/100 Accelerated weathering resistance: Gloss 60 retention 92% ΔE = 1.9 Secondary adhesion: 100/100. A similar coated plate was prepared using the coating composition prepared in Comparative Example 2 and tested in the same manner.
Rust formation was found in the accelerated weathering test.

Test Example 3 The clear paint prepared in Example 3 was applied on an ABS resin plate to prepare a coating film having a film thickness of 20 μm. Using this coated plate, a test was conducted by the method shown in Test Example 1. The results are shown below. Initial adhesion: 100/100 Accelerated weathering resistance: Gloss retention rate 85% ΔE = 2.4 Secondary adhesion: 100/100. A coated plate was prepared in the same manner using the coating composition prepared in Comparative Example 2, and the same test was conducted.
The secondary adhesion after accelerated weathering was 20/100.

[0040]

EFFECT OF THE INVENTION The fluororesin coating composition of the present invention is an organic compound containing a fluorine-containing copolymer prepared by copolymerizing predetermined monomers, an ultraviolet absorber and / or a light stabilizer, an organic solvent and a crosslinking agent. Since it is of a solvent type, the durability against ultraviolet rays is further imparted to the fluororesin coating excellent in water resistance and chemical resistance. Therefore, even when this is used as a clear paint or a color clear paint having a low pigment concentration, the base can be continuously protected for a long period of time.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Inukai 1-1 Funami-cho, Minato-ku, Nagoya City Toagosei Chemical Industry Co., Ltd. Nagoya Research Institute

Claims (1)

[Claims] 1. A fluororesin coating composition comprising the components shown in the following (1) to (4). (1) a) Fluoroolefin monomer unit: 30 to 60
Mol% b) hydroxyalkyl crotonic acid monomer unit: 3 to 3
0 mol% c) Copolymerizable vinyl monomer units other than the above: 10
Fluorine-containing copolymer composed of 67 mol% (2) UV absorber and / or light stabilizer (3) Organic solvent (4) Crosslinking agent capable of reacting with hydroxyl group