JP2005272499A - Powdery coating material containing silicate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a powdery coating material inhibiting the progress of the solid phase reaction of an organic silicate compound and capable of giving a coating film having good fouling resistance. <P>SOLUTION: This silicate-containing powdery coating material is obtained by mixing a raw material powdery coating material and an organic silicate compound at a temperature lower than the softening point of the raw material powdery coating material. The above mixing can be the one in which the organic silicate compound in the form of being dissolved in a solvent is added into the raw material powdery coating material and then the solvent is evaporated off. The solvent can be the one having a boiling point of ≤150°C, and the mass of the organic silicate compound can be 0.1-10% against the mass of the raw material powdery coating material. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a powder coating material containing an organic silicate compound and a coating film having a stain resistance obtained therefrom.

  It is known that stain resistance can be imparted to the resulting coating film by adding an organic silicate compound to the paint. Many of the paints to be added have been mainly solvent type so far, but recently they have been applied to powder paints.

  On the other hand, in a powder coating, it is known that an organic silicate compound is deactivated by a solid phase reaction with a hydroxyl group of a binder component. In order to solve this, it has been proposed to use an ethylsilicate compound having a specific solubility (see Patent Document 1).

By the way, the expression of stain resistance is thought to be due to the migration and hydrolysis of the organic silicate compound on the surface of the coating film, but compared to the solvent type, the organic silicate compound is applied to the coating film surface. Migration was difficult, and when the previous ethyl silicate compound was used, the previous solid-phase reaction could be suppressed, but it was difficult to develop sufficient contamination resistance.
JP 2002-294170 A

  An object of this invention is to obtain the powder coating material which prevents the progress of the solid-phase reaction of an organic silicate compound, and can obtain the coating film which has sufficient stain resistance.

  The silicate-containing powder coating material of the present invention is obtained by mixing a raw material powder coating material and an organic silicate compound below the softening point of the raw material powder coating material. Here, the mass of the organic silicate compound may be 0.1 to 10% with respect to the mass of the raw material powder coating material. The organic silicate compound may contain a resin portion. Further, the mixing may be performed by adding the organic silicate compound in a form dissolved in a solvent to the raw powder coating material, and then distilling off the solvent, and the boiling point of the solvent may be 150 ° C. or less.

In the method for producing a silicate-containing powder coating material of the present invention, a raw material powder coating material and an organic silicate compound are mixed below the softening point of the raw material powder coating material.
The coating film having stain resistance of the present invention is obtained from the above powder coating material.

  Since the silicate-containing powder coating of the present invention can prevent the progress of the solid phase reaction, a coating film having sufficient stain resistance can be obtained. This is because a large amount of the organic silicate compound is present near the surface of the powder coating particle by mixing the raw material powder coating and the organic silicate compound below the softening point of the raw material powder coating. It is thought that. That is, in this state, the solid phase reaction hardly proceeds, and as a result, the deactivation of the organic silicate compound is considered to be minimized. In addition, when there are many organic silicate compounds in the vicinity of the paint particle surface, when the particles are melted, the organic silicate compound easily migrates to the surface of the coating film, and even if the addition amount is small, sufficient stain resistance is expressed. It is thought that it is made. In addition, some pigments and additives tend to adsorb organic silicate compounds as they are, but in the state of powder coating particles after melt-kneading, binder resin or the like adheres to these surfaces. By doing so, the area of the surface that adsorbs the organic silicate compound is reduced, and it is considered that the adsorption of the added organic silicate compound can be minimized.

  In the method for producing a silicate-containing powder coating according to the present invention, since many organic silicate compounds can be present in the vicinity of the particle surface of the obtained powder coating, compared to the case where the organic silicate compound is added during normal melt-kneading. The amount of the organic silicate compound used can be reduced.

  The silicate-containing powder coating material of the present invention is obtained by mixing a raw material powder coating material and an organic silicate compound below the softening point of the raw material powder coating material. The raw material powder coating is not particularly limited, and a normal powder coating can be used.

  The raw material powder coating generally contains a binder resin and a main component of a curing agent, and usually other components such as a pigment, a curing catalyst, and an additive.

  Examples of the binder resin and the curing agent include those usually used for powder coatings. As the binder resin, a polyester resin, an epoxy resin, or an acrylic resin having a functional group capable of reacting with a curing agent is usually used. Further, these can be appropriately blended to be used as a polyester / epoxy resin, an acrylic / epoxy resin, or an acrylic / polyester resin.

  The polyester resin can be obtained by polycondensation using an ordinary method using an acid component mainly composed of a polyvalent carboxylic acid and an alcohol component mainly composed of a polyhydric alcohol as raw materials. The acid component is not particularly limited, and examples thereof include terephthalic acid, isophthalic acid, phthalic acid and anhydrides thereof, aromatic dicarboxylic acids such as 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, and the like. Anhydrides, succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, saturated aliphatic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, and their anhydrides, lactones such as γ-butyrolactone, ε-caprolactone, etc. And aromatic oxymonocarboxylic acids such as p-oxyethoxybenzoic acid, hydroxycarboxylic acids corresponding to these, and the like.

  The alcohol component is not particularly limited, and examples thereof include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, and triethylene. Glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, bisphenol A alkylene oxide adduct, bisphenol S alkylene oxide adduct, 1,2-propanediol, neopentyl glycol, 1,2-butanediol, , 3-butanediol, 1,2-pentanediol, 2,3-pentanediol, 1,4-pentanediol, 1,4-hexanediol, 2,5-hexanediol, 3-methyl-1,5-pentane Diol, 1,2-dodecandioe It can be exemplified aliphatic glycols having a side chain such as 1,2-octadecanediol, trimethylolpropane, glycerin, a trivalent or higher polyhydric alcohols such as pentaerythritol or the like.

  By controlling the kind and amount of the compound contained in each of the acid component and the alcohol component, a polyester resin having a predetermined amount of functional groups capable of reacting with the curing agent can be obtained. In addition, a polyester resin with high weather resistance can be obtained by containing 50 mass% or more, preferably 80 mass% or more of isophthalic acid in the acid component.

  Moreover, the said acrylic resin can be obtained by mix | blending an ethylenically unsaturated group containing monomer, and copolymerizing this using a normal method. Examples of the ethylenically unsaturated group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl acrylate, Plaxel FM and FA series (trade name, 2-hydroxyethyl (Meth) acrylate and polycaprolactone adduct, manufactured by Daicel Chemical Industries, Ltd.), hydroxyl group-containing monomers such as polyalkylene glycol mono (meth) acrylates, epoxy groups such as glycidyl acrylate, glycidyl methacrylate, and 2-methylglycidyl methacrylate Monomers, amino group-containing monomers such as dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, (meth) acrylamide, N-methyl (meth) acrylamide Curing functional group-containing monomers such as acrylamide monomers such as N-butoxymethyl (meth) acrylamide and N-methylacrylamide, carboxylic acid group-containing monomers such as (meth) acrylic acid, acrylonitrile, vinyl acetate, (meth) acrylic Others such as methyl acid, ethyl (meth) acrylate, n-butyl (meth) acrylate, iso-butyl (meth) acrylate, tert-butyl (meth) acrylate, styrene, vinyltoluene, p-chlorostyrene Neutral monomers can be exemplified. By appropriately blending these ethylenically unsaturated group-containing monomers, an acrylic resin having a predetermined amount of functional groups capable of reacting with the curing agent is obtained.

  Furthermore, the epoxy resin is a compound having an epoxy group as a functional group capable of reacting with two or more curing agents in one molecule, for example, glycidyl ester resin, bisphenol A and epichlorohydrin. Glycidyl ether type resins such as condensation reaction products and condensation reaction products of bisphenol F and epichlorohydrin, alicyclic epoxy resins, aliphatic epoxy resins, bromine-containing epoxy resins, phenol novolac type epoxy resins, cresol novolac type epoxy Resin etc. can be illustrated.

  On the other hand, when the functional group of the binder resin is a hydroxyl group, an aliphatic polyvalent carboxylic acid, an aliphatic acid anhydride, an amino resin, a polyepoxy compound, a blocked isocyanate compound, a glycoluril curing agent, or the like is used as the curing agent. It is done. When the functional group of the binder resin is a carboxyl group, examples of the curing agent include polyepoxy compounds, polyhydroxy compounds, and β-hydroxyalkylamide compounds. Further, when the functional group of the binder resin is an epoxy group, the curing agent is an aliphatic polycarboxylic acid such as decanedicarboxylic acid or sebacic acid, a polyvalent carboxylic acid anhydride, dicyandiamide, a blocked isocyanate compound, or an amine type. Examples thereof include a curing agent, a polyamide-based curing agent, a phenol resin, imidazoles, and imidazolines.

  The ratio between the binder resin and the curing agent is preferably such that the functional groups involved in the curing do not deviate significantly from the stoichiometrically equivalent amount ratio.

  Next, what is generally used can be used as said pigment as another component. Specifically, titanium dioxide, bengara, yellow iron oxide, carbon black, phthalocyanine blue, phthalocyanine green, quinacridone pigments, azo pigments and other colored pigments, metallic pigments, pearl pigments, metal powders and surface treatments. And extender pigments such as talc, silica, calcium carbonate and precipitated barium sulfate. The content of the pigment in the raw material component of the powder coating material is not particularly limited, but generally it is preferably 30 to 100% by mass with respect to the total amount of the binder resin and the curing agent. .

  On the other hand, a tin compound is well known as the curing catalyst, and examples of the additive include a surface conditioner, a plasticizer, an ultraviolet absorber, an antioxidant, an anti-waxing agent, a charge control agent, and a fluidity imparting agent. It is done. These components are used as long as their functions can be expressed and other performances are not impaired.

  The raw material powder coating material may contain an organic silicate compound. Examples of the organic silicate compound include those described later. When the raw material powder coating material contains an organic silicate compound, the amount thereof is 0.1 to 1% by mass relative to the total amount of the raw material powder coating material. preferable.

  The raw material powder coating is preliminarily mixed with the above raw material components using a super mixer, Henschel mixer, etc., and then put into a kneader such as a kneader or an extruder to perform melt kneading, and then It is obtained by cooling, coarsely pulverizing, further finely pulverizing and pulverizing and classifying to a desired particle size. The conditions for melt kneading can be appropriately selected depending on the raw material components used. Moreover, it is preferable that the particle size is 5-50 micrometers in a volume average particle diameter. These adjustments can be performed by classification for adjusting the particle size distribution by removing large particles and fine particles.

  The raw material powder coating material for obtaining the silicate-containing powder coating material of the present invention may be a commercially available powder coating material. In this case, it is preferable from the point of determination of the addition amount of an organic silicate compound to use the component which comprises a powder coating material, and those ratios known.

  The organic silicate compound as another raw material for obtaining the silicate-containing powder coating material of the present invention is a tetraalkoxysilane having a C 1-8 alkoxy group and a condensate thereof, and a modification of this condensate. is there.

  Specific examples of the tetraalkoxysilane having an alkoxy group having 1 to 8 carbon atoms include tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane, tetrahexyloxysilane, and tetraoctyloxysilane. Among these condensates, a tetramethoxysilane condensate and a tetraethoxysilane condensate are commercially available from Mitsubishi Chemical as the MKC silicate MS series and from Colcoat as the ethyl silicate series, respectively. As a kind of alkoxy group which the said tetraalkoxysilane and its condensate have, a C1-C4 thing is preferable from a reactive viewpoint, and a C1-C2 thing is especially preferable.

  On the other hand, examples of the modified condensate include those obtained by substituting the alkoxy group of the condensate with an alcohol and those modified with a polymer. Substitution of the alkoxy group of the condensate with an alcohol varies depending on whether the alcohol used is a monoalcohol or a diol. That is, in the case of a monoalcohol, by substituting the alkoxy group of the condensate with the alkoxy group of the monoalcohol, the hydrolyzability of the organic silicate compound and the compatibility in the paint and / or coating film The purpose of denaturation is to control each of these.

  On the other hand, when the alcohol used is a diol, a reaction between an alkoxy group of the condensate and an alkoxy group of the diol between one molecule of the diol and two molecules of the condensate results in two molecules of the condensate. A modified product in which is linked by a diol is obtained. Thus, by further repeating this reaction, the molecular weight of the organic silicate compound can be reduced without performing condensation, which is difficult to adjust, and without using a low-reactivity and bulky alkoxy group. Can be increased.

  When the alkoxy group of the condensate is substituted with a monoalcohol, it can be obtained by performing an exchange reaction using 1 mol or more of monoalcohol with respect to 1 mol of the condensate. In terms of reactivity, the condensate is preferably a condensate of tetramethoxysilane and / or tetraethoxysilane. The amount of the monoalcohol can be appropriately increased in accordance with the number of target substituents. The above reaction is preferably performed by heating to about 150 ° C., for example. Moreover, in order to advance reaction, it is preferable to make the system pressure reduction and to distill off produced | generated methanol or ethanol out of the system. The reaction is terminated when a predetermined amount of substitution with alcohol is performed. After completion of the reaction, the target silicate compound can be obtained by performing separation and purification as necessary. The silicate compound thus obtained is generally a colorless to light yellow oily substance. In addition, the determination of the substitution amount with the alcohol is performed by checking the amount of methanol or ethanol produced or using an analytical instrument.

  Examples of the monoalcohol include ethanol, propanol, butanol, benzyl alcohol, 2-butoxyethanol, 3-methoxy-1-propanol, 2-ethylhexanol, and octanol.

  On the other hand, when the alkoxy group of the condensate is substituted with a diol, it can be obtained by performing an exchange reaction using 1 mol of the condensate in an amount of 0.6 mol times or less. If the amount exceeds 0.6 mole times, gelation may occur. The reaction can be carried out in the same manner as for the monoalcohol, but the resulting product can be further reacted by adding a diol of 0.5 mol times or less. The modified product thus obtained is a silicate obtained by removing one alkoxy group from the condensate of tetraalkoxysilane to the oxygen atoms at both ends of the diol unit obtained by removing hydrogen atoms from the two hydroxyl groups of the diol. Although each unit has a structure bonded to each other, at least one of the silicate units may be bonded to another silicate unit via another diol unit.

  In addition, in the substitution of the alkoxy group of the condensate with an alcohol, a solvent is not particularly required. However, when used, the solvent may be 10 times or less with respect to the total mass of the condensate and the monoalcohol. preferable. Specific examples of the solvent include, for example, aromatic hydrocarbons such as toluene, benzene and xylene, halogenated hydrocarbons such as dichloroethane, ethers such as THF and dioxane, ketones such as methyl ethyl ketone and methyl isobutyl ketone, ethyl acetate and Examples include esters such as butyl acetate, dimethyl carbonate, and acetonitrile.

  In the exchange reaction, an acid or a base can be used as a catalyst as necessary. Examples of the acid include Bronsted acids such as hydrochloric acid, sulfuric acid, phosphoric acid and sulfonic acid, and Lewis acids such as organotin compounds. Examples of the base include triethylamine, dimethylbenzylamine, diazabicyclo [2.2.2. A tertiary amine such as octane or 1,8-diazabicyclo [5.4.0] undecene-7 can be used.

  Another polymer modification of the condensate is to introduce a resin portion into the organic silicate compound by reacting the alkoxy group of the condensate with the hydroxyl group of the polyol. This modification is usually performed to adjust the compatibility with the paint or coating film components. The condensate modified here includes not only the above condensate but also one obtained by replacing this with an alcohol.

  Examples of the polyol include acrylic resins, polyester resins, polyether resins, polyurethane resins, and fluorine resins having a hydroxyl value of 5 to 300 and a number average molecular weight of 500 to 20000. The solid content mass ratio of the condensate (including alcohol substitution product) / polyol in the polymer modification can be 0.1 / 1 to 10/1. The reaction itself can be carried out based on the above monoalcohol substitution method.

  In addition, the description about the said organic silicate compound is applied also to the organic silicate compound which may be contained in the raw material powder coating material.

  The mass of the organic silicate compound is preferably 0.1 to 10% with respect to the mass of the raw material powder coating material. If it is less than 0.1%, the stain resistance is not sufficient, and if it exceeds 10%, the stability of the powder coating is lowered. In the silicate-containing powder coating of the present invention, the effect of stain resistance can be exhibited even in an amount of 1% or less by adjusting the conditions.

  The mixing of the raw material powder coating material and the organic silicate compound is performed below the softening point of the raw material powder coating material. The softening point is obtained by measuring based on a standard, and when the raw material powder paint is a commercial product, the value can be obtained from a catalog. The mixing method is not particularly limited. For example, the raw powder coating material is put in a suitable container, the organic silicate compound is added thereto, and the mixture is stirred using a suitable instrument. it can. Moreover, according to the amount to mix, the apparatus for mixing, such as a kneader and a mixer, can also be used.

  In this mixing, the organic silicate compound is dissolved in a solvent and this solution is added to the raw powder coating material, whereby the raw powder coating material can be uniformly mixed on the particle surface. The amount of the solvent can be, for example, 1 to 100 times the mass of the organic silicate compound.

  The solvent needs to dissolve the organic silicate compound, but it is preferable that the solvent does not dissolve or hardly dissolve the raw material powder coating material. Furthermore, the solvent in which the organic silicate compound is dissolved is finally distilled off. The solvent is preferably distilled off by reducing the pressure. If necessary, the solvent can be heated as long as it does not adversely affect the resulting paint. For this reason, the solvent is preferably highly volatile, and specifically, a solvent having a boiling point of 150 ° C. or less. Examples of such solvents include pentane, hexane, heptane, octane, toluene, xylene, methanol, ethanol, butanol, ethyl acetate, butyl acetate, methyl isobutyl ketone and the like.

  In this way, the silicate-containing powder coating material of the present invention can be obtained. If necessary, it is preferable to classify and remove those particles that have been increased in particle size by bonding between particles, which are generated during the mixing. By doing so, the particle size of the silicate-containing powder coating material of the present invention is substantially the same as the particle size of the raw material powder coating material. That is, the volume average particle diameter is preferably 5 to 50 μm. When it is used for thin film coating, it is preferably 5 to 40 μm, and more preferably 5 to 30 μm, particularly when it is desired to obtain a thin and smooth coating film.

In the method for producing a silicate-containing powder coating material of the present invention, a raw material powder coating material and an organic silicate compound are mixed below the softening point of the raw material powder coating material. For the details, reference is made to the above description of the silicate-containing powder coating.

  The coating film having stain resistance of the present invention is obtained from the above powder coating material. Specifically, a coating film having excellent stain resistance can be obtained by applying the previously obtained stain-resistant powder coating material to a substrate and then baking it. The base material is not particularly limited as long as it does not cause defects such as deformation due to baking after coating, and specifically, iron plates, steel plates, aluminum plates, and the like, and surface treatments thereof may be mentioned. Can do. Since the coating film of the present invention has stain resistance, the substrate is preferably applied to vending machines, switchboards, building exterior materials, steel structures and the like installed outdoors. Note that an undercoat coating film obtained from an undercoat paint such as a primer may be formed on the substrate.

  The application is not particularly limited, and methods well known by those skilled in the art, such as an electrostatic coating method and a fluid dipping method, can be used. From the viewpoint of coating efficiency, the electrostatic coating method is preferable. Examples of the charging method in the electrostatic coating method include a corona charging method and a friction charging method. These methods can also be used in combination. Although a coating film thickness is not specifically limited, For example, it can be set as 20-200 micrometers. The baking after application can be performed at 140 to 220 ° C. for 5 to 40 minutes based on the type of binder resin and curing agent used. In this way, a coating film having stain resistance can be obtained.

  2.0 g of MKC silicate 56 (manufactured by Mitsubishi Chemical Corporation) was dissolved in 50 g of hexane to prepare a hexane solution. As a raw material powder paint, 200 g of powder paint P-510 clear (polyester polyol / block isocyanate curing system, average particle size 34 μm), a powder paint manufactured by Nippon Paint Co., Ltd., was weighed into a ball, and 2 ml of the above hexane solution was added here. Was sprayed using a spray bottle and stirred for about 1 minute using a stir bar. The spraying and stirring of the hexane solution was repeated until the hexane solution disappeared, and mixing was performed. From the mixture thus obtained, hexane was distilled off under reduced pressure to obtain a silicate-containing powder coating having an average particle size of 37 μm.

  4.0 g of MKC silicate 56 was dissolved in 100 g of hexane to prepare a hexane solution. As a raw material powder coating material, 200 g of Powderx P-510 clear was charged in a desktop kneader, and 4 ml of the hexane solution was sprayed using a sprayer and stirred for about 1 minute. The spraying and stirring of the hexane solution was repeated until the hexane solution disappeared, and mixing was performed. From the mixture thus obtained, hexane was distilled off under reduced pressure to obtain a silicate-containing powder coating having an average particle size of 40 μm.

  2.0 g of MKC silicate 56 was dissolved in 50 g of hexane to prepare a hexane solution. As a raw material powder coating material, 200 g of powder paint P-510 (polyester polyol / block isocyanate curing system, average particle size 39 μm), a powder coating material manufactured by Nippon Paint Co., Ltd., was charged into a universal stirring mixer, and 30 hexane solution was added while stirring. Gradually added over minutes to mix. From the mixture thus obtained, hexane was distilled off while heating to 25 to 35 ° C. under reduced pressure to obtain a silicate-containing powder coating having an average particle size of 39 μm.

  A silicate-containing powder coating having an average particle size of 40 μm was obtained in the same manner as in Example 3 except that the amount of MKC silicate 56 was 4.0 g, the amount of hexane was 100 g, and the hexane solution was adjusted.

  In Example 1, instead of Powderx P-510 clear, the same amount was used except that the same amount of fine particle powder coating material Vilicia PL-1000 (polyester polyol / block isocyanate curing system, average particle size 18 μm) manufactured by Nippon Paint Co., Ltd. was used. Thus, a silicate-containing powder coating having an average particle size of 23 μm was obtained.

  2.0 g of ethyl-substituted methyl silicate (ethyl group / methyl group ratio = 18/82, weight average molecular weight 2500) was dissolved in 50 g of hexane to prepare a hexane solution. As a raw material powder coating material, 200 g of Powderx P-510 was charged into a universal stirring mixer, and the hexane solution was gradually added over 30 minutes while stirring to perform mixing. Hexane was distilled off from the mixture thus obtained while heating to 25 to 35 ° C. under reduced pressure to obtain a silicate-containing powder coating having an average particle size of 42 μm.

  A silicate-containing powder coating material having an average particle size of 40 μm was obtained in the same manner as in Example 6 except that the amount of ethyl-substituted methyl silicate was changed to 1.0 g.

  A silicate-containing powder coating having an average particle size of 39 μm was obtained in the same manner as in Example 6 except that the amount of ethyl-substituted methyl silicate was changed to 0.4 g.

Comparative Example 1
Based on Production Example 1 of Japanese Patent Application Laid-Open No. 2002-294170, 2-butoxyethanol and triethylamine are added to ethyl silicate 48 (condensate having an average condensation degree of tetraethoxysilane of 10 manufactured by Colcoat Co.), and the produced ethanol is removed. Then, the remaining 2-butoxyethanol was removed under reduced pressure to obtain an ethyl silicate compound substituted with three 2-butoxyethoxy groups. 2.0 g of this ethyl silicate compound was mixed with 200 g of raw material components constituting Powderx P-510, and a silicate-containing powder coating having an average particle size of 35 μm was obtained by a normal powder coating manufacturing method.

Comparative Example 2
In the same manner as in Comparative Example 1, except that the amount of the ethylsilicate compound was increased to 4.0 g, a silicate-containing powder coating having an average particle size of 35 μm was obtained.

Comparative Example 3
In Example 1, except that the amount of MKC silicate 56 was changed to 30 g, an attempt was made to prepare a silicate-containing powder coating material. The resulting coating material flowed as a powder in a moist and moist state. There was no property, and it was not in a state where powder coating was possible.

Evaluation <Contamination Resistance>
The silicate-containing powder coatings of Examples 1 to 8 and Comparative Examples 1 and 2 were applied to a test panel using a coating gun and baked at 190 ° C. for 25 minutes to obtain coating films, respectively. The water contact angle was measured after the coating film had been placed under conditions of a temperature of 20 ° C. and a humidity of 50% for 1 month, and the presence or absence of rain streaks exposed outdoors for 3 months was visually confirmed. The water contact angle is measured using a CA-A type contact angle measuring device manufactured by Kyowa Interface Science Co., Ltd. If it is less than 60 degrees, the surface is sufficiently hydrophilized and considered to be excellent in stain resistance. It is.

<Solid phase reactivity>
The silicate-containing powder coatings of Examples 1 to 8 and Comparative Examples 1 and 2 were stored at 35 ° C. for 4 weeks, and the presence or absence of blocking was visually evaluated.
The evaluation results are summarized in Table 1.

  In the silicate-containing powder coating of the example of the present invention, even with a small content, a coating film having good contamination resistance was obtained, and the progress of the solid phase reaction was not observed. On the other hand, when a silicate-containing powder coating material is produced by a conventional method using the ethylsilicate compound disclosed in Japanese Patent Application Laid-Open No. 2002-294170, a content rate of 1% is sufficient as shown in Comparative Example 1. The contamination resistance could not be expressed. For this reason, when the addition amount is increased in Comparative Example 2, the contamination resistance is certainly improved, but this time the solid-phase reaction proceeds. On the other hand, in Example 8 of the present invention, it was confirmed that a coating film having good stain resistance could be obtained even with a content of only 0.2%.

  Since the silicate-containing powder coating material of the present invention can obtain a coating film having stain resistance, its aesthetic appearance can be maintained by applying it to an article placed outdoors.

Claims (6)

  A silicate-containing powder paint obtained by mixing a raw material powder paint and an organic silicate compound below the softening point of the raw material powder paint.   The silicate-containing powder coating material according to claim 1, wherein a mass of the organic silicate compound is 0.1 to 10% with respect to a mass of the raw material powder coating material.   The silicate-containing powder according to any one of claims 1 and 2, wherein the mixing is performed by adding the organic silicate compound in a form dissolved in a solvent to the raw powder coating material, and then distilling off the solvent. Body paint.   The silicate-containing powder coating material according to claim 3, wherein the solvent has a boiling point of 150 ° C or lower.   A method for producing a silicate-containing powder paint, comprising mixing a raw material powder paint and an organic silicate compound below a softening point of the raw material powder paint.   The coating film which has the stain resistance obtained from the powder coating material of any one of Claims 1-4.