JPH0959559A - Coating composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtaina coating composition containing a specific fluoroolefin copolymer and zinc oxide powder having specified particle diameter, exhibiting high storage stability and workability and giving a coating film having excellent transparency. SOLUTION: (A) A fluoroolefin polymer having a fluorine content of >=5wt.%, an acid value of 0.1-150mgK0H/g and a number-average molecular weight of <=10,000 determined by GPC using polystyrene as a standard substance is compounded with (B) 3-500 pts.wt. (based on 100 pts.wt. of the component A) of zinc oxide powder having a weight-average particle diameter of 0.0001-0.1μm. The fluoroolefin used as a copolymerization raw material for the component A is preferably tetrafluoroethylene or chlorotrifluoroethylene and the copolymerized monomer is preferably a vinyl monomer other than fluoroolefins. A curing reaction part is preferably introduced into the component A e.g. by the copolymerization of a monomer having curing reaction part such as hydroxyethyl vinyl ether.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating composition, and more particularly to a coating composition capable of providing a coating film having good storage stability, excellent workability and excellent transparency.

[0002]

2. Description of the Related Art Conventionally, a coating composition containing a fluoroolefin copolymer has been known as a coating composition which gives a coating film having excellent weather resistance. This fluoroolefin copolymer for paints has high weather resistance, long-term use, excellent protection function for construction and civil engineering structures, and extremely low maintenance such as cleaning and repainting. (JP-A-62-22862, etc.). When a coating composition containing this fluoroolefin copolymer is used as a coating composition for protecting a clear undercoat, an ultraviolet absorber has been added.

[0003]

However, conventional organic UV absorbers have a short service life, and inorganic UV absorbers such as zinc oxide, titanium oxide, and cerium oxide are difficult to disperse, and storage stable coatings and It was difficult to obtain a transparent coating film. An object of the present invention is to provide a coating composition having good storage stability, excellent workability, and capable of providing a coating film having excellent transparency, and a coated article thereof.

[0004]

The present invention provides (a) a fluorine content of 5% by weight or more and an acid value of 0.1 to 150 mgK.
OH / g and G when polystyrene is used as a standard substance
A fluoroolefin copolymer having a number average molecular weight of 10,000 or less measured by PC and (b) a zinc oxide powder having a weight average particle diameter of 0.0001 to 0.1 μm,
The ratio of component (b) to 100 parts by weight of component (a) is 3
The coating composition is about 500 parts by weight.

The component (a) used in the coating composition of the present invention has a fluorine content of 5% by weight or more and an acid value of 0.1.
150 mgKOH / g, the number average molecular weight measured by GPC is 1000 when polystyrene is used as a standard substance.
It is a fluoroolefin-based copolymer having 0 or less.

If the fluorine content is too low, sufficient weather resistance cannot be obtained, and if the acid value is outside this range, sufficient solution dispersibility and coating film transparency cannot be obtained, and the number average molecular weight is 100.
If it exceeds 00, the transparency of the coating film becomes insufficient.

The preferred range of acid value is 0.1 to 50 mgK
OH / g, more preferably 1.0-10 mg KOH / g
It is. The preferable range of the number average molecular weight is 2000 to 10.
000, and more preferably 3000 to 8000.

The fluoroolefin copolymer having a fluorine content of 5% by weight or more is a copolymer using fluoroolefin as a fluorine-based monomer as a copolymerization raw material.
Examples of such fluoroolefins include tetrafluoroethylene, chlorotrifluoroethylene, hexafluoropropylene, vinylidene fluoride, vinyl fluoride and the like. Preferred fluoroolefins are tetrafluoroethylene and chlorotrifluoroethylene.

A vinyl-based monomer other than fluoroolefin is preferably used as the copolymerization monomer. And Such vinyl monomer, carbon represented by CH ₂ = CH- - a compound having a carbon double bond. Examples of the vinyl monomer include vinyl ether, allyl ether, vinyl carboxylate, allyl carboxylate, and olefin.

As the vinyl ether, cycloalkyl vinyl ether such as cyclohexyl vinyl ether,
Examples thereof include alkyl vinyl ethers such as nonyl vinyl ether, 2-ethylhexyl vinyl ether, hexyl vinyl ether, n-butyl vinyl ether, t-butyl vinyl ether and ethyl vinyl ether. Examples of the allyl ether include alkyl allyl ether such as ethyl allyl ether and cycloalkyl allyl ether such as hexyl allyl ether.

Examples of the carboxylic acid vinyl ester or the carboxylic acid allyl ester include vinyl or allyl esters of carboxylic acids such as acetic acid, butyric acid, pivalic acid and benzoic acid. As the vinyl ester of a carboxylic acid having a branched alkyl group, commercially available Veova-9 and -10 (both manufactured by Shell Chemical Co., Ltd.) may be used. Examples of olefins include ethylene and isobutylene.

The above-mentioned copolymerizable monomers may be used alone or in combination of two or more.

The fluoroolefin copolymer used in the present invention has a group for giving an acid value of 0.1 to 150 mgKOH / g, for example, a carboxyl group. Further, the fluoroolefin copolymer has an acid value of 0.1 to 150 m.
In addition to the group for giving gKOH / g, it is preferable to have a curing reactive site that reacts with a curing agent.

The curing reactive site can be appropriately selected depending on the combination with a curing agent, and typical examples thereof include a hydroxyl group, a carboxyl group, a hydrolyzable silyl group, an epoxy group and an amino group. The carboxyl group is
It can be used as a group for giving an acid value of 0.1 to 150 mg KOH / g and also as a curing reactive site that reacts with a curing agent.

As a method of introducing such a curing reactive site, there is a method of copolymerizing a monomer having a curing reactive site during a copolymerization reaction.

Examples of the monomer having a curing reactive site include hydroxyalkyl vinyl ethers such as hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether and cyclohexanediol monovinyl ether, and hydroxyalkyl allyl ethers such as 2-hydroxyethyl allyl ether. Group-containing monomers, acrylic acid, methacrylic acid, maleic acid, crotonic acid, and other carboxyl group-containing monomers, triethoxyvinylsilane and other hydrolyzable silyl group-containing monomers, glycidyl vinyl ether, glycidyl allyl ether, β-methylglycidyl ether Examples thereof include a monomer having an epoxy group, a monomer having an amino group such as aminopropyl vinyl ether, and the like.

Further, a curing reactive site can be introduced by a post reaction after the polymerization of the fluoroolefin polymer. For example, a method of introducing a hydroxyl group by saponifying a polymer obtained by copolymerizing a carboxylic acid vinyl ester, and a method of introducing a carboxyl group by reacting a polyvalent carboxylic acid or its anhydride with a polymer having a hydroxyl group. , A method of introducing a water-decomposable silyl group by reacting an isocyanate alkoxysilane, a method of reacting a polyvalent silyl isocyanate compound and introducing an isocyanate group.

Regarding the method of introducing the carboxyl group for giving an acid value to the fluoroolefin copolymer, the method of introducing the carboxyl group as the above-mentioned curing reactive site may be adopted.

The fluoroolefin copolymer as the component (a) may be used alone or in combination of two or more. Fluoroolefin-based copolymers include
Other resins may be used in combination.

Examples of other resins include acrylic resins, polyester resins, polyurethane resins in which the polyol component is acrylic polyol or polyester polyol, silicone resins, acrylic silicone resins, fluororesins other than the fluoroolefin copolymer in the present invention. Can be mentioned.

These other resins may have a curing reactive site. The other resins may be used alone or in combination of two or more. The amount of the other resin to be blended may be appropriately selected within a range that does not impair the object of the present invention. Usually, the fluoroolefin copolymer 100 is used.
1 to 200 parts by weight is preferable with respect to parts by weight.

The component (b) in the present invention is a zinc oxide powder having a weight average particle diameter of 0.0001 to 0.1 μm. If the particle diameter is too large, the dispersibility of the zinc oxide powder in the coating composition of the present invention is not sufficient, which is not preferable. The preferable range of particle diameter is 0.001 to 0.1 μm.
And a particularly preferable range is 0.01 to 0.1 μm.

As the zinc oxide powder in the present invention, a usual zinc oxide powder can be used as long as the weight average particle diameter is 0.0001 to 0.1 μm. Commercially available products are Sumitomo Osaka Cement's zinc oxide ZnO-100, Mitsubishi Materials' C
-30, F-60, etc. These zinc oxide powders may be mixed with a solvent such as xylene or cyclohexanone, or with a dispersant, and made into a paste or dispersion state.

The mixing ratio of each component in the coating composition of the present invention is such that the component (a) fluoroolefin copolymer 1
3 parts by weight of zinc oxide powder as the component (b) is added to 100 parts by weight.
It is 500 parts by weight, preferably 100 to 300 parts by weight, and particularly preferably 150 to 250 parts by weight.

The coating composition of the present composition preferably contains a curing agent for the purpose of improving the solvent resistance of the coating film. As the curing agent, for example, an ordinary curing agent for coating materials such as an isocyanate curing agent, a blocked isocyanate curing agent and a melamine curing agent can be used. Isocyanate curing agents include non-yellowing isocyanates such as hexamethylene diisocyanate and isophorone diisocyanate.Blocked isocyanate curing agents include those whose isocyanate groups are blocked with caprolactam, isophorone, β-diketone, and melamine curing. Examples of the agent include melamine etherified with a lower alcohol such as butylated melamine and epoxy-modified melamine.

The curing agent is preferably contained in an amount of 1 to 100 parts by weight, more preferably 1 to 50 parts by weight, based on 100 parts by weight of the resin of component (a) having a curing reactive site. If the amount of the curing agent is less than 1 part by weight, the solvent resistance and hardness will be insufficient, and the amount of the curing agent will be 10
If it exceeds 0 parts by weight, the workability and impact resistance may decrease, which is not preferable.

The coating composition of the present invention can be diluted with an organic solvent depending on the required viscosity. When the coating composition of the present invention is dissolved or dispersed in an organic solvent, examples of the solvent include hydrocarbons such as toluene, xylene and mineral spirit, alcohols such as n-butanol and isobutanol, ethyl acetate, butyl acetate and the like. Esters of
Ketones such as methyl ethyl ketone and methyl isobutyl ketone, glycol ethers such as ethylene glycol monoethyl ether, and the like can be used. Various commercially available thinners can also be used, and these can be used by mixing them at an appropriate ratio.

Coloring pigments or dyes, silane coupling agents for improving the adhesion of coating films, ultraviolet absorbers and the like can be added to the coating composition of the present invention.

Examples of the coloring pigment or dye include carbon black having good weather resistance, inorganic pigments such as titanium oxide, phthalocyanine blue, phthalocyanine green,
Examples include organic pigments or dyes such as quinacridone red, indanthrene orange, and isoindolinone yellow.

If desired, a curing accelerator, a light stabilizer, a matting agent, etc. may be added to the coating composition of the present invention. As the curing accelerator, dibutyltin dilaurate or the like can be used for the isocyanate type curing agent, and an acidic catalyst such as paratoluene sulfonic acid can be used for the melamine type curing agent.

Examples of the light stabilizer include hindered amine-based light stabilizers, and specific examples thereof include ADEKA STAB LA62 (trade name, manufactured by Adeka Argus Chemical Co., Ltd.).
And ADEKA STAB LA67 (trade name of Adeka Argus Chemical Co., Ltd.), Tinuvin 292, Tinuvin 144, CGL-12
3, Tinubin 440 (all manufactured by Ciba Geigy, trade name) and the like.

Examples of the matting agent include ultrafine synthetic silica, and when a matting agent is used, an elegant semi-glossy or matte finish coating film can be formed.

A surfactant may be added to the coating composition of the present invention. Since the surfactant controls the surface tension, it is effective for adjusting the surface concentration of a specific component. These surfactants may be of nonionic, cationic, or anionic type, and may be manufactured by Dai-ichi Kogyo Seiyaku Rheorex ASE (Dai-ichi Kogyo Seiyaku, trade name), fluorine-based surfactant Surflon S.
382 (manufactured by Asahi Glass, trade name), acrylic Modaflow (manufactured by Monsanto, trade name), Leofat series (manufactured by Kao, trade name) and the like.

The coating composition of the present invention can be produced by mixing the above essential components (a) and (b) and various additives which are added as necessary. The mixing order is not particularly limited, and the mixing order may be such that the component (a) and the additive are mixed in advance and the component (b) is mixed therein, or the component (a) and the component (b) are mixed in advance, Then, a mixing order in which the additives are mixed may be used.

As a method of coating using the coating composition of the present invention, any method such as spray coating, dipping method, roll coater and flow coater can be applied.

The material of the article to be coated includes, for example, concrete, natural stone, inorganic substances such as glass, and metals such as iron, stainless steel, aluminum, copper, brass and titanium. It is also suitable for coating organic substrates, that is, plastics, rubbers, adhesives, wood and the like. In particular, it is suitable for coating on a coating film already formed. It is also suitable for coating organic-inorganic composite materials such as FRP, resin reinforced concrete, and fiber reinforced concrete.

The articles to be coated include transportation equipment such as automobiles, trains and airplanes, bridge members, civil engineering members such as steel towers, waterproof materials, industrial materials such as tanks and pipes, building exteriors, doors, window gate members. , Monuments, construction materials such as poles, medians of roads, road rails such as guardrails and soundproof walls, communication equipment, electric and electronic parts.

[0038]

【Example】

"Production Example 1" Chlorotrifluoroethylene / ethyl vinyl ether / hydroxybutyl vinyl ether / cyclohexyl vinyl ether = 50/25/10/15 mol% fluoroolefin copolymer (hydroxyl value: 50 m
gKOH / g, number average molecular weight: 7,000) was reacted with maleic anhydride to adjust the acid value to 2 mgKOH / g (hydroxyl value is 48 mgKOH / g). This copolymer is designated as A.

[Production Example 2] Fluoroolefin copolymer (chlorohydric value: 118 mgKOH / g, number average molecular weight: 4000) of chlorotrifluoroethylene / ethyl vinyl ether / hydroxybutyl vinyl ether = 50/30/20 mol%. The copolymer is referred to as D.), and maleic anhydride is reacted to give an acid value of 5 mgKOH /
g (hydroxyl value is 113 mg KOH / g). Let this copolymer be B.

"Production Example 3" Chlorotrifluoroethylene / ethyl vinyl ether / hydroxybutyl vinyl ether / cyclohexyl vinyl ether = 50/25/1
0/15 mol% fluoroolefin copolymer (hydroxyl value: 50 mg KOH / g, number average molecular weight: 1200
0) to maleic anhydride to give an acid value of 2 m
gKOH / g (hydroxyl value is 48 mgKOH / g
g). Let this copolymer be C.

In the above Production Examples 1 to 3, the number average molecular weight is measured by GPC when polystyrene is used as a standard substance. Further, each of the copolymers A to D had a fluorine content of 5% or more.

[Examples 1 to 2 (Examples) and Examples 3 to 4 (Comparative Examples)] Zinc oxide powders (manufactured by Osaka Cement Co., weight average particle diameter) in the mixing ratios shown in Table 1 for the above copolymers A to D. 0.05
μm zinc oxide powder (abbreviated as powder E) or a dispersion liquid in which 50% by weight of powder E is dispersed in cyclohexanone (abbreviated as powder F)], solvent (xylene) and curing agent (isocyanate curing agent manufactured by Nippon Polyurethane Co., Ltd.) Coronate H
X) was mixed to prepare a coating composition, which was coated on an acrylic adhesive coat of a fluororesin film (tetrafluoroethylene-ethylene copolymer) by 4 μm and dried.

The properties of the coating composition and the physical properties of the coating film were measured, and the results are shown in the lower part of Table 1. The measurement was performed by the following method.

(1) Solution dispersibility: The state in the glass container was visually judged. The sedimentation, aggregation, and transparency were evaluated comprehensively. The one having good solution dispersibility was marked with "O", and the one having poor solution dispersibility was marked with "X".

(2) Pot life: The time required for the solution to gel and solidify after blending the isocyanate curing agent is 4
Those that exceeded the time were rated as "O", and those that did not exceed 4 hours were rated as "X".

(3) Transparency of coating film: The state of the film was visually evaluated. A sample with good transparency was marked with "O", and a sample with poor transparency was marked with "X".

[0047]

[Table 1]

[0048]

EFFECTS OF THE INVENTION According to the coating composition of the present invention, a zinc oxide powder can be favorably dispersed, the pot life is long, the workability is good, and a transparent coating film is obtained.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Shoichi Kawakami 2-23-1, Hatchobori, Chuo-ku, Tokyo Asahi Glass Court Andresin Co., Ltd.

Claims (4)

[Claims] (A) Fluorine having a fluorine content of 5% by weight or more, an acid value of 0.1 to 150 mgKOH / g, and a number average molecular weight of 10,000 or less measured by GPC when polystyrene is used as a standard substance. Olefin-based copolymer and (b) weight average particle diameter of 0.0001 to 0.1 μ
A coating composition containing the zinc oxide powder of m, and the ratio of the component (b) to 100 parts by weight of the component (a) is 3 to 500 parts by weight. 2. The coating composition according to claim 1, wherein the fluoroolefin-based copolymer is a copolymer of fluoroolefin and a vinyl-based monomer other than fluoroolefin and has a carboxyl group. 3. The coating composition according to claim 1, which contains an isocyanate curing agent, a blocked isocyanate curing agent or a melamine curing agent. 4. A coated article obtained by coating the coating composition of claim 1, 2 or 3 on an article.