JP2551115B2 - Paint composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a composition for a fluororesin coating having excellent weather resistance.

[Prior Art] Conventionally, a coating composition containing a solvent-soluble hydroxyl group-containing fluorine-containing copolymer as an essential component is known as a coating composition that gives a coating film having excellent weather resistance. For example, in JP-A-57-34107 and JP-A-58-136662,
A solvent-soluble fluorine-containing copolymer and a coating composition containing the fluorine-containing copolymer, which are essential components of a coating composition, are described.

[Problems to be Solved by the Invention] In a conventional coating film having excellent weather resistance, stains contained in rainwater, muddy water, etc. remain in spots or streaks on the coating film surface when exposed to wind and rain. , The appearance is impaired. In addition, it has been pointed out that this dirt cannot be easily removed by simple wiping with water. On the other hand, there is also known a method of solving the above-mentioned stain problem by forming a coating film of a hydrophilic acrylic resin, but this coating film has a problem that the water resistance and weather resistance are extremely poor.

The present invention is intended to provide a coating composition which is excellent in weather resistance and gives a coating film whose appearance is not damaged by wind and rain.

[Means for Solving Problems] The present invention has been made to solve the above-mentioned problems, and is a coating composition containing the following fluorine-containing copolymer (A) and fluorine-containing copolymer (B). It is a thing.

(A) Fluorine-containing copolymer having a fluorine content of 10% by weight or more based on fluoroolefin having 2 to 3 carbon atoms (B) Amide group, polyethylene glycol chain, sulfonate group, sulfate ester group, phosphate ester group A fluorine-containing copolymer obtained by copolymerizing a monomer having a hydrophilic group selected from a carboxylic acid group, a quaternary ammonium salt group, and an amine group and a monomer having a polyfluoroalkyl group having 3 or more carbon atoms. In the above, as the fluorine-containing copolymer (A) having a fluorine content of 10% by weight or more based on the fluoroolefin, a copolymer of fluoroolefin and a monomer copolymerizable therewith is adopted. As the fluorine-containing copolymer (A), those which are soluble or dispersible in an organic solvent or water are preferably adopted from the viewpoint of coatability. Preferably, a fluoroolefin having 2 or 3 carbon atoms such as tetrafluoroethylene, chlorotrifluoroethylene, trifluoroethylene, vinylidene fluoride, hexafluoropropylene, pentafluoropropylene and vinyl ether, vinyl ester, allyl ether, allyl ester, acrylic acid. , A copolymer with at least one monomer selected from acrylic acid ester, methacrylic acid, and methacrylic acid ester. When the copolymerization ratio of the fluoroolefin is too small, the weather resistance which is sufficiently excellent as the weather resistant coating cannot be exhibited. The fluoroolefin copolymerization ratio is preferably such that the fluorine content based on the fluoroolefin in the copolymer is 10% by weight. Further, if the copolymerization ratio of the fluoroolefin is too large, the solubility in the solvent and the compatibility with the below-mentioned fluorocopolymer (B) are deteriorated, which is not preferable.
Preferably, the fluoroolefin is a fluorocopolymer copolymerized at a ratio of 30 to 70 mol%. Further, it is preferable that the fluorine-containing copolymer (A) is copolymerized with a compound as described above in addition to the fluoroolefin from the viewpoint of solubility in a solvent and the like. Particularly, vinyl ether, vinyl ester, allyl ether, and allyl ester are preferable from the viewpoint of excellent copolymerizability with fluoroolefin. In particular,
Alkyl vinyl ether, alkyl vinyl ester, alkyl allyl ether and alkyl allyl ester having a linear, branched or alicyclic alkyl group having about 1 to 10 carbon atoms are preferable.

Further, it is preferable that the fluorinated copolymer (A) has a curing reactive site in addition to the above-mentioned copolymerization components, because a tougher coating film can be obtained. As the curing reactive site, an active hydrogen-containing group capable of reacting with an isocyanate-based curing agent or an aminoplast-based curing agent such as a hydroxyl group, an amino group, an acid amide group, a carboxylic acid group, or the like,
Examples thereof include epoxy group, halogen, double bond, hydrolyzable silyl group and the like. Such a curing reactive site is introduced by a method of copolymerizing a monomer having a curing reactive site, for example, hydroxyalkyl vinyl ether, hydroxyalkyl allyl ether, glycidyl vinyl ether, acrylic acid, or modifying the copolymer. By introducing a curing reactive site, for example, a hydroxyl group or an epoxy group is reacted with a polycarboxylic acid anhydride to introduce a carboxylic acid group, and an isocyanate alkyl acrylic acid is reacted to introduce a double bond. The method of doing is illustrated. The copolymerized unit having a curing reactive site is preferably 5 to 20 mol% in the copolymer.
In particular, it is preferable that the ratio of the monomer having a curing reactive site to the total monomer is 5 to 20 mol%.

It is important that the composition of the present invention contains a fluorine-containing copolymer (B) obtained by copolymerizing a monomer having a polyfluoroalkyl group having 3 or more carbon atoms and a hydrophilic group-containing monomer. . Here, the monomer having a polyfluoroalkyl group having 3 or more carbon atoms usually has a polyfluoroalkyl group having about 3 to 18 carbon atoms, preferably 3 to 10 carbon atoms, and particularly preferably a perfluoroalkyl group. A monomer is adopted, and examples thereof include unsaturated esters such as the following acrylates and methacrylates.

CF ₃ (CF ₂ ) ₄ CH ₂ OCOC (CH ₃ ) = CH ₂ CF ₃ (CF ₂ ) ₆ (CH ₂ ) ₂ OCOC (CH ₃ ) = CH ₂ CF ₃ (CF ₂ ) ₆ COOCH = CH ₂ CF ₃ (CF ₂ ) ₇ CH ₂ CH ₂ OCOCH = CH ₂ CF ₃ (CF ₂ ) ₇ SO ₂ N (C ₃ H ₇ ) (CH ₂ ) ₂ OCOCH = CH ₂ CF ₃ (CF ₂ ) ₇ (CH ₂ ) ₄ OCOCH = CH ₂ CF ₃ (CF ₂ ) ₇ SO ₂ N (CH ₃ ) (CH ₂ ) ₂ OCOC (CH ₃ ) = CH ₂ CF ₃ (CF ₂ ) ₇ SO ₂ N (C ₂ H ₅ ) (CH ₂ ) ₂ OCOCH = CH ₂ CF ₃ (CF ₂ ) ₇ CONH (CH ₂ ) ₂ OCOCH = CH ₂ CF ₃ (CF ₂ ) ₈ (CH ₂ ) ₂ OCOCH = CH ₂ CF ₃ (CF ₂ ) ₈ (CH ₂ ) ₂ OCOC (CH ₃ ) = CH ₂ CF ₃ (CF ₂ ) ₈ CONH (CH ₂ ) ₂ OCOC (CH ₃ ) = CH ₂ H (CF ₂ ) ₁₀ CH ₂ OCOCH = CH ₂ CF ₂ Cl (CF ₂ ) ₁₀ CH ₂ OCOC (CH ₃ ) = CH ₂ In the present invention, as the monomer having a polyfluoroalkyl group, a vinyl ether having a polyfluoroalkyl group having 3 to 18 carbon atoms, preferably 3 to 10 carbon atoms, and particularly preferably a perfluoroalkyl group may be adopted. it can. For example, the following polyfluoroalkyl group-containing alkyl vinyl ethers can be exemplified.

CF ₃ (CF ₂ ) ₅ CH ₂ CH ₂ OCH ₂ CH ₂ OCH = CH ₂ CF ₃ (CF ₂ ) ₇ CH ₂ CH ₂ OCH = CH ₂ CF ₃ (CF ₂ ) ₅ CH ₂ CH ₂ OCH = CH _{2 As a} matter of course, as a monomer having a polyfluoroalkyl group, It is also possible to employ a monomer that also has a functional group that provides a curing reactive site as described above.

In the present invention, the hydrophilic group-containing monomer is a hydrophilic group selected from amide groups, polyethylene glycol chains, sulfonate groups, sulfate ester groups, phosphate ester groups, carboxylate groups, quaternary ammonium groups and amine bases. Group-containing acrylic, methacrylic, vinyl,
An allyl compound or the like is adopted. In particular, an acrylic, methacrylic, or vinyl compound is preferably used from the viewpoint of copolymerizability with the polyfluorinated carbon chain-containing monomer. Also,
As the hydrophilic group, an amide group or a polyethylene glycol chain is less likely to have a bad influence on the coating film, and is therefore preferably used.

Specifically, polyethylene glycol chain-containing compounds such as polyethylene glycol methacrylate, polyethylene glycol acrylate, methoxy polyethylene glycol methacrylate, and methoxy polyethylene glycol acrylate, and amide group-containing compounds such as acrylamide, methacrylamide, and N-vinyl-lactam compounds. And so on. Here, as the polyethylene glycol chain, one having about 3 to 20 repeating units represented by —CH ₂ CH ₂ O— is preferably adopted. Further, the N-vinyl-lactam compound is Is an organic cyclic compound containing an atomic group in the ring, specifically, N-vinyl-β-propiolactam, N-vinyl-2-pyrrolidone, N-vinyl-γ-valerolactam,
Examples include N-vinyl-2-piperidone, N-vinyl-ε-caprolactam, N-vinyl-heptalactam and the like. However, those having too large a ring are not preferable because they do not exhibit hydrophilicity. Preferred is an N-vinyl-lactam compound having a 7-membered ring or less. Particularly, N-vinyl-2-pyrrolidone is preferably used because of its excellent stability.

The copolymerization ratio of the monomer having a polyfluoroalkyl group and the monomer having a hydrophilic group is 1 to 30% by weight, preferably 3 to 30% by weight of the monomer having a polyfluoroalkyl group.
Copolymerized at a ratio of 10% by weight and 50% hydrophilic group-containing monomer
It is preferable that the copolymerization is performed in a proportion of not less than wt%.
When the copolymerization ratio of the monomer having a polyfluoroalkyl group is 1% by weight or less, the effect of concentrating the hydrophilic group in the vicinity of the coating film surface is not sufficiently exerted, and in order to achieve the object of the present invention, A large amount of the specific fluorine-containing copolymer (B) is required, which is not preferable. Further, when a large amount of the specific fluorine-containing copolymer (B) is used as described above, many hydrophilic groups are present inside the coating film, and the water resistance of the coating film is lowered, which is not preferable. Further, when the copolymerization ratio of the monomer having a polyfluoroalkyl group is 30% by weight or more, the hydrophilicity of the specific fluorine-containing copolymer (B) decreases, and the object of the present invention cannot be achieved. If the copolymerization ratio of the hydrophilic group-containing monomer is too low, the object of the present invention will not be achieved.

Further, it is preferable that the fluorine-containing copolymer (B) has a curing reactive site because the effect can be maintained for a long period of time. The curing reactive site is a group that reacts with the curing reactive site of the fluorocopolymer (A),
And a group that reacts with the curing agent. In particular,
Examples thereof include hydroxyl groups, carboxylic acid groups, amino groups, epoxy groups, acid amide groups and the like, which are the same as those described in the curing reactive site of the fluorine-containing copolymer (A). Further, these curing-reactive sites are monomers having curing-reactive sites,
For example, by introducing 2-hydroxymethacrylate, hydroxyethylpropylmethacrylate, 2-hydroxyethylacrylate, glycidylmethacrylate, methacrylic acid, etc. by copolymerizing with the monomer having a polyfluoroalkyl group and the hydrophilic group-containing monomer. can do. Also, a hydrophilic group-containing monomer, or
When a monomer having a curing reactive site such as a hydroxyl group is used as the monomer having a polyfluoroalkyl group, the monomer having a curing reactive site may not be copolymerized.

In the present invention, it is preferable to add the fluorocopolymer (B) in a specific amount to the fluorocopolymer (A).
That is, 1 to 50 parts by weight, preferably 5 to 20 parts by weight of the fluorocopolymer (B) per 100 parts by weight of the fluorocopolymer (A).
It is selected from the range of parts by weight. If the blending amount of the polyfluoroalkyl group-containing polymer is too small, the surface properties of the coating film such as antifouling property and stain-removing property are not sufficiently improved, and if it is too large, the surface hardness of the coating film and solvent resistance are low. The physical properties of the coating film such as properties and impact resistance may be impaired, and the weather resistance and water resistance of the coating film may be deteriorated.

In preparing the composition of the present invention, various solvents can be used, and aromatic hydrocarbons such as xylene and toluene, alcohols such as n-butanol, esters such as butyl acetate, and methyl isobutyl ketone. In addition to ketones and glycol ethers such as ethyl cellosolve, various commercially available thinners can be used. Further, the mixing with the solvent can be carried out by using various equipments which are usually used for coating such as a ball mill, a paint shaker, a jet mill, a triple roll and a kneader. At this time, a pigment, a dispersion stabilizer, a viscosity modifier, a leveling agent, an anti-gelling agent, an ultraviolet absorber and the like can also be added.

The composition of the present invention is capable of co-crosslinking the fluorocopolymer (A) and the fluorocopolymer (B) with various curing agents to form a cured coating film having excellent physical properties. is there. In this case, various curing agents can be used depending on the curing-reactive site of the above-mentioned two types of fluorine-containing copolymers. Examples of the curing agent include aminoplasts, polyvalent isocyanate compounds, polybasic acid compounds, polyvalent amine compounds, polyacrylic compounds, and metal alkoxides. For example, fluorinated copolymer (A)
When the curing reactive site of (B) is an active hydrogen-containing group, it is used as a curing agent in ordinary acrylic paints and the like. Aminoplast, polyvalent isocyanate compound,
A polyvalent acid compound or its anhydride can be used. As the aminoplast, melamine resin, guanamine resin, urea resin and the like can be used. Examples of the melamine resin include butylated melamine, methylated melamine, and epoxy-modified melamine. Further, a melamine resin etherified with a lower alcohol such as methanol, ethanol, propanol, butanol can also be used. Examples of the urea resin include methylated urea resin and ethylated urea resin. As the polyvalent isocyanate compound, non-yellowing isocyanates such as hexamethylene diisocyanate and isophorone diisocyanate, and their blocked products and multimers can be used.
Further, as the polybasic acid compound, long-chain aliphatic dicarboxylic acids, aromatic polyvalent carboxylic acids or their anhydrides are useful. When aminoplast, a block polyvalent isocyanate compound, or a polybasic acid compound is used as the curing agent, the fluorine-containing copolymers (A) and (B) can be heat-co-crosslinked. When a polyvalent isocyanate compound that is not blocked is used, it can be co-crosslinked at room temperature. When aminoplast is used as the curing agent, co-crosslinking can also be promoted by adding an acidic catalyst. When a polyvalent isocyanate compound is used as the curing agent, co-crosslinking can be promoted by adding a known catalyst such as dibutyltin dilaurate.

The composition of the present invention has distinctiveness, mechanical strength, adhesiveness,
Additives such as pigments, colorants, fillers and stabilizers may be appropriately added for the purpose of durability and the like. Typical of such additives are phthalocyanine green, titanium oxide, alumina, talc, calcium carbonate,
Examples thereof include silica.

The composition of the present invention is not limited to metals such as iron, aluminum, copper or alloys thereof (eg stainless steel, brass), but also inorganic materials such as glass, cement and concrete, FRP, polyethylene, polypropylene, ethylene-
Vinyl acetate copolymer, polyamide, polyacrylic, polyester, ethylene-vinyl alcohol copolymer, vinyl chloride resin, vinylidene chloride resin, polycarbonate,
It can be applied to various substrates such as plastics such as polyurethane, organic materials such as wood and fibers, and various substrates having a coating layer. Also, the shape of the base material is not limited to a flat plate,
Even complex shapes can be easily constructed. Further, since it can be installed on site, it can be applied to large structures.

Other than the above, as long as the object and spirit of the present invention are not impaired,
Of course, appropriate additions and changes can be made. For example, the base material to which the composition of the present invention is applied may be appropriately subjected to pretreatment or surface treatment, or the composition of the present invention may be applied after appropriately undercoating or precoating. Further, the composition of the present invention may be configured as a two-component type or a two-component type with a curing agent liquid.

[Function] In the present invention, since the polyfluoroalkyl group of the fluorocopolymer (B) has a low surface energy, it migrates to the air interface side in the process of forming a coating film, and as a result, the hydrophilic property of copolymerization is increased. It is considered that the groups are concentrated near the surface.

In the dry state of the coating film, it has a water repellent surface due to the polyfluoroalkyl group, but when exposed to a large amount of water, the polyfluorinated carbon chains exposed on the surface are reversed,
It is considered that the hydrophilic groups migrate to the surface and the surface becomes hydrophilic.

Since the fluorinated copolymer (B) is concentrated only near the surface, and the surface has water repellency when the coating is dried, the coating as a whole exhibits high water resistance and high weather resistance of the fluororesin coating. Since the hydrophilic surface can be formed while keeping it, it is considered that the property that the spot-like or streak-like stain seen in the weather-resistant thermosetting coating film does not easily occur is exhibited.

[Examples] The present invention will be specifically described below with reference to Examples and Comparative Examples.

Examples 1 to 8 and Comparative Examples 1 to 5 were prepared using t-butanol, a monomer having the composition shown in Table 1.
In a sec-butanol mixed solvent, azobisisobutyronitrile was used as an initiator for polymerization at 65 ° C to synthesize fluorine-containing copolymers A-1 to A-4.

In Table 1, Veova 9 is a trade name (made by Ciel Chemical Co., Ltd.) vinyl ester of a saturated carboxylic acid having a branched structure having 9 carbon atoms, and azobisisobutyro is a monomer having the composition shown in Table 2 in ethyl acetate. Polymerization was carried out at 60 ° C. using nitrile as an initiator to synthesize fluorine-containing copolymers B-1 to B-8.

In Table 2, FMA is CH ₂ = C (CH ₃ ) COO-C ₂ H ₄ CF _{2 n} F (n = 4 to 10 mixture) M-40G is CH ₂ = C (CH ₃ ) COOCH ₂ CH ₂ O _m CH ₃ (m = 4) PE-200 is CH ₂ = C (CH ₃ ) COOCH ₂ CH ₂ O ₁ H (1 = mixture of 4 to 5) AAm is CH ₂ = CHCONH ₂ BMA Am is CH ₂ = CHCONH-CH ₂ OC ₄ H ₉ HEMA is 2-hydroxyethylmethacrylate MAA is methacrylic acid n-BMA is n-butylmethacrylate A-1 to 4 and B-1 to 8 Was used to prepare a composition having the composition (parts by weight) shown in Table 3.

Next, the above composition was applied on an aluminum plate that had been treated with allodin, and the coating film obtained by drying at 140 ° C. for 30 minutes was subjected to a stain resistance test, an outdoor exposure test, and an accelerated weather resistance test. The results are shown in Table 4.

Example 9 The procedure of Example 1 was repeated except that the curing agent was 33 parts by weight of a block isocyanate type curing agent (C2507; manufactured by Nippon Polyurethane Co., Ltd.). The obtained coating film was water, n-decane,
Also in the contact angle of n-octane (in water), the stain resistance test, the outdoor exposure test, and the weather resistance test, almost the same results as in Example 1 were obtained.

Example 10 The same procedure as in Example 1 was carried out except that the curing agent was 25 parts by weight of a polyvalent isocyanate curing agent (Coronate EH; manufactured by Nippon Polyurethane Co., Ltd.) and the drying condition was room temperature for 7 days. The obtained coating film had almost the same results as in Example 1 in contact angles of water, n-decane, and n-octane (in water), stain resistance test, outdoor exposure test, and weather resistance test.

The stain resistance test, outdoor exposure test, and weather resistance test were carried out by the following methods.

Staining test Adhesion is determined by spraying a 0.1% by weight carbon black distilled water dispersion on the coating surface and then drying it for 10 minutes in a 90 ° C dryer for 6 minutes. The state of dirt due to was observed.

(A: stain spreads all over, ○: stain becomes slightly spotted, Δ: stain becomes spotted, ×: stain becomes clearly spotted) In addition, the cleaning property is after the above adhesion test. The dirty coated surface was wiped with water and then the coated surface was observed.

(◎: No trace of dirt remains, ○: Almost no trace, △: Trace remains, ×: Clear trace remains) Outdoor exposure test After outdoor exposure, dirt adhered to the shape of the trace of rainwater flow It was confirmed whether or not.

Weather resistance test Gloss retention (%) was measured after 3,000 hours of sunshine weather au meter.

[Effects of the Invention] The composition of the present invention does not impair the weather resistance of weather-resistant paints, does not cause conspicuous stains such as spotted lines and streaks, which have been problems of conventional weather-resistant paints, and stains A coating film that easily falls can be provided. Further, it is also extremely excellent in water repellency and oil repellency, and is extremely useful as a weather-resistant coating that is maintenance-free and wax-free.

Claims (3)

(57) [Claims] 1. A coating composition containing the following fluorocopolymer (A) and fluorocopolymer (B). (A) Fluorine-containing copolymer having a fluorine content of 10% by weight or more based on fluoroolefin having 2 to 3 carbon atoms (B) Amide group, polyethylene glycol chain, sulfonate group, sulfate ester group, phosphate ester group , A fluorinated copolymer in which a monomer having a hydrophilic group selected from a carboxylic acid group, a quaternary ammonium salt group and an amine group and a monomer having a polyfluoroalkyl group having 3 or more carbon atoms are copolymerized. 2. The fluorine-containing copolymer (A) has 2 to 3 carbon atoms.
Fluoro-olefin of 30-70 mol%, other monomer 70-30
The coating composition according to claim 1, which is a fluorine-containing copolymer copolymerized in a mol% ratio. 3. The fluorine-containing copolymer (B) contains 50% by weight or more of the monomer having the hydrophilic group and 1 to 30% by weight of the monomer having the polyfluoroalkyl group having 3 or more carbon atoms. The coating composition according to claim 1 or 2, which is a fluorine-containing copolymer copolymerized at a ratio of.