Coating material composition for outdoor use

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to an outdoor coating composition containing titanium dioxide as a pigment, and more specifically, a titanium dioxide pigment-containing outdoor coating material capable of forming a coating film having improved weather resistance by reducing the photocatalytic activity of the titanium dioxide pigment. It relates to a paint composition for use.

【0002】

[Conventional technology]

When a painted object coated with outdoor paint is exposed to the outdoor natural environment, various conditions such as atmospheric composition, rain, snow, humidity, wind, dust, and salt are duplicated, and the coating surface is deteriorated, eroded, and painted. It is widely known that it causes phenomena such as discoloration of the film, deterioration of gloss, whitening, embrittlement, and generation of cracks. In the paint industry, the durability against the deterioration phenomenon of the coating film in such an outdoor natural environment is called the weather resistance of the coating film, and the expected performance has been extended to 20 years, 30 years or maintenance-free these days. Therefore, improving the weather resistance of the coating film has become a very important issue.

【0003】

The following two are the main causes of deterioration of the coating film in the outdoor natural environment. One of them is called photooxidation deterioration, which is caused by the influence of light and oxygen. In this kind of deterioration, the weakly bonded part of the polymer constituting the coating film absorbs light and becomes an excited state, and is further attacked by oxygen to generate a hydroperoxide group, and the polymer is decomposed in a chain reaction. It is known to be caused by this. The other is called photocatalytic deterioration due to the titanium dioxide pigment, which is a deterioration phenomenon peculiar to the titanium dioxide pigment-containing coating film. In this photocatalytic deterioration, titanium dioxide absorbs short-wavelength light to generate pairs of electrons and holes, and at the same time, water and oxygen act to act on OH radicals and O.₂H radicals are generated, which are caused by decomposing the polymers that make up the coating.

【0004】

Under such circumstances, as a method for improving the weather resistance of the coating film, a method of using a titanium dioxide pigment in a state where its photocatalytic activity is suppressed, a method of selectively using a polymer having less photooxidation deterioration as a coating film forming polymer, A method of copolymerizing or mixing an ultraviolet absorber or a radical trapping agent with a coating film-forming polymer, a method of overcoating a clear paint on a titanium dioxide-containing coating film, or a method of applying an ultraviolet absorber or an ultraviolet absorber to this clear paint. Methods for blending a radical trapping agent and the like are known, and some of them are generally used.

【0005】

[Problems to be Solved by the Invention]

Each of the above methods has its own characteristics, and especially if it is considered in terms of disadvantages, the weather resistance performance of the method alone is often insufficient, and therefore it must be combined with any of the methods of. In many cases, there are restrictions on the application of the method due to the characteristics of the polymer, and the cost is significantly increased. In many cases, the weather resistance performance is insufficient or the cost is in the negative direction. In addition, the method has a problem that the number of painting steps increases once.

【0006】

The present invention is based on the fact that by using a titanium dioxide pigment in a state where its photocatalytic activity is sufficiently suppressed, sufficient weather resistance can be exhibited even by the above method alone, and a coating film having improved weather resistance. It is an object of the present invention to provide an outdoor coating composition capable of forming the above.

【0007】

[Means for solving problems]

As a result of diligent studies to achieve the above problems, the present inventor has sufficiently suppressed the photocatalytic activity and improved the weather resistance by using the titanium dioxide pigment as the titanium dioxide-containing suspension polymer beads. The present invention has been completed by finding that an outdoor coating composition capable of forming a coating film can be obtained. That is, the outdoor coating composition of the present invention is characterized by containing a titanium dioxide pigment as titanium dioxide-containing suspended polymer beads.

【0008】

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in more detail. In ordinary paints including outdoor weather resistant paints, titanium dioxide pigments are directly dispersed in the coating film forming polymer. On the other hand, in the present invention, when the polymer beads are produced by the suspension polymerization method, a titanium dioxide pigment is contained in the beads, and the beads are mixed and dispersed in the polymer for forming a coating film. By such a treatment, the transmission of ultraviolet rays to the titanium dioxide pigment and the contact between the titanium dioxide pigment and water or oxygen are alleviated, and the photocatalytic deterioration reaction due to titanium dioxide is significantly reduced, so that the weather resistance of the coating film is improved. Greatly improved.

【0009】

The titanium dioxide-containing suspension polymer beads used in the present invention can be produced, for example, by the following method. First, the titanium dioxide pigment to be blended is mixed in a polymer solution and kneaded and dispersed with a media mill or the like so that almost the entire amount of titanium dioxide has a primary particle size of 220 to 290 nm to obtain a titanium dioxide paste. .. As this titanium dioxide, a general pigment 1 titanium dioxide whose crystal structure produced by the sulfuric acid method or the chlorine method is surface-treated in a rutile type can be widely used, and from the viewpoint of improving weather resistance, it is treated with dense silica. And a zircon-treated product are preferable.

【0010】

As the above-mentioned polymer solution for dispersing titanium dioxide, a solvent solution containing a polyester resin, an acrylic resin, an acrylic silicone resin, a fluoropolymer resin, etc., which are generally used for paints, can be widely used, and the weather resistance is improved. From the point of view, it is preferable to use a solvent solution of acrylic resin or acrylic silicone resin.

【0011】

As the above solvent, aromatic hydrocarbons, ester solvents, ketone solvents, and general paint solvents such as alcohols and glycol ethers can be widely used. If a large amount of solvent is required to obtain the titanium dioxide paste, make sure that the general paint solvent does not exceed 20% by weight of the total amount of the paste, and use a polymerizable monomer such as methyl methacrylate as the solvent. It is preferable to use it as a part of the above from the viewpoint of stabilization of the bead production process, yield and the like.

【0012】

Further, as a media mill for kneading and dispersing the titanium pigment, a general sand mill, attritor, ball mill or the like can be used. Further, it is preferable to knead and disperse most of the titanium dioxide particles in the titanium dioxide paste until the primary particle size is 220 to 290 nm. This treatment facilitates inclusion of titanium dioxide in the polymer beads obtained in a later step, and reduces the exposure of titanium dioxide particles from the polymer beads or the phenomenon of titanium dioxide alone popping out.

【0013】

Next, as an example of preferable titanium dioxide-containing suspended polymer beads, a method for producing titanium dioxide-containing suspended acrylic polymer beads will be described. The above-mentioned titanium dioxide paste and polymerization initiator are dissolved in the monomers for obtaining the acrylic polymer beads, mixed with an aqueous solution of a dispersion stabilizer, pre-emulsified with a homogenizer or the like, and this emulsification system is transferred to a polymerization can. , Suspension polymerization is carried out to obtain an acrylic polymer bead aqueous dispersion containing titanium dioxide and having a particle size of 0.1 to 30 μm.

【0014】

As the monomers for obtaining the acrylic polymer beads, methyl methacrylate alone or a mixture of methyl methacrylate and other vinyl monomers copolymerizable therewith can be used. Other copolymerizable vinyl monomers include ethyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, cyclohexyl (meth) acrylate, and the like. Examples thereof include (meth) acrylic acid esters, methacrylic acid, acrylic acid, acrylonitrile, styrene, maleic acid, fumaric acid and their esters, or monomers such as ethylene glycol diacrylate and trimethylpropane triacrylate. These vinyl monomers can be used alone or in combination of two or more with methyl methacrylate, and the amount used is the heat resistance, weather resistance or mechanical properties of the obtained copolymer beads, and solvent resistance. It may be appropriately determined depending on the sex, and generally, it is within 30% by weight in the monomer mixture.

【0015】

As the polymerization initiator, one known for polymerizing vinyl monomers can be used. For example, azo compounds such as 2,2'-azobis (2,4-dimethylvaleronitrile), azobisisobutyronitrile, dimethyl-2,2'-azobisisobutyrate, t-butylperoxypipalate, Peroxy esters such as t-butylperoxy-2-ethylhexanoate and cumylperoxy-2-ethylhexanoate, and diacylpers such as di-8,5,6-trimethylhexanoyl peroxide and dilauroyl peroxide. Organic peroxides such as oxides can be mentioned, and one or a mixture of two or more of these can be used. The amount of these polymerization initiators added is preferably in the range of 0.02 to 2.0% by weight with respect to the weight of the monomer.

【0016】

In the method for producing acrylic polymer beads, a well-known chain transfer agent can be used to adjust the molecular weight of the polymer, if necessary. Examples of such chain transfer agents include alkyl mercaptan, alkyl sulfide, alkyl disulfide, thioglycolic acid ester, α-methylstyrene dimer and the like.

【0017】

Examples of the dispersion stabilizer include anionic polymer compounds such as polyacrylic acid, sodium polyacrylate, potassium polyacrylate, polymethacrylic acid, sodium polymethacrylate, and sodium methacrylate-alkyl methacrylate copolymer. Among them, sodium polyacrylate and sodium polymethacrylate are preferable.

【0018】

Further, as a dispersion stabilizer, nonionic polymer compounds such as polyvinyl alcohol, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, polyethylene oxide, polyoxyethylene-polyoxypropylene block copolymer, polyoxyethylene lauryl ether, and polyoxyethylene cetyl. Water-soluble polymer compounds such as ether, polyoxyethylene nonylphenyl ether, polyethylene glycol fatty acid ester, and polyoxyethylene laurylamine can also be used, and among them, a polyoxyethylene-polyoxypropylene copolymer is preferable.

【0019】

These anion-based or nonionic-based water-soluble polymer compounds as dispersion stabilizers can be used alone or in combination of two or more kinds, and as a method of adding the aqueous solution to the polymerization system, collectively. Alternatively, it can be added separately or continuously. However, a method is adopted in which the anionic polymer compound is added before the polymerization, the polymerization proceeds, and the nonionic polymer compound is added when the polymerization rate of the monomer reaches 20 to 80%, preferably 25 to 75%. Then, the amount of the dispersion stabilizer remaining in the polymer beads is small, and the stability of the polymerization system is good, so this addition method is preferable.

【0020】

The amount of each of the anion-based and nonionic water-soluble polymer compounds added is selected from the range of 0.01 to 2.0% by weight, preferably 0.1 to 1.0% by weight with respect to the weight of the monomer, but the polymerization system is stable. It is preferable that the amount used is as small as possible. If the amount of the water-soluble polymer compound added is less than 0.01% by weight, the polymerization system becomes unstable, and if it exceeds 2.0% by weight, the residual rate in the granular polymer tends to increase, which is not preferable. ..

【0021】

Further, as a dispersion stabilizer, a general anionic surfactant such as sodium dodecylbenzenesulfonate, sodium dialkylsulfosuccinate and the like can also be used. These can be used in an addition amount in the range of 0.005 to 2.0% by weight based on the weight of the monomer. If the addition amount is less than 0.005% by weight, the stability of the polymerization system is poor, and if it exceeds 2.0% by weight, the residual rate in the granular polymer tends to increase, which is not preferable.

【0022】

It is also possible to use an inorganic salt in combination with the above-mentioned water-soluble polymer compound or surfactant. Examples of these inorganic salts include boric acid, sodium carbonate, disodium hydrogen phosphate, sodium dihydrogen phosphate, sodium sulfate and the like, and these inorganic salts are in the range of 0.01 to 2.0% by weight based on the weight of the monomer. It is preferable to use in the amount of addition.

【0023】

When producing acrylic polymer beads, the mixing ratio of the mixture consisting of monomers, titanium dioxide paste and polymerization initiator and the aqueous solution of the dispersion stabilizer is preferably 1: 1 to 1:10, more preferably. The range is 1: 1 to 1: 4. If the amount of the aqueous solution of the dispersion stabilizer is too small, the dispersion of the monomer in which the titanium dioxide paste is dissolved tends to be non-uniform and the polymerization system becomes unstable. On the contrary, if the amount of the aqueous solution of the dispersion stabilizer is too large, the production efficiency is improved. It is disadvantageous.

【0024】

When producing acrylic polymer beads having a desired particle size by suspension polymerization using the above-mentioned polymerization system consisting of an aqueous solution of monomers, titanium dioxide paste, polymerization initiator and dispersion stabilizer, a well-known turbine blade, It is also possible to carry out suspension polymerization directly under appropriate polymerization conditions in a polymerization vessel equipped with a stirrer equipped with stirring blades such as a Faudler blade, a propeller blade and a blue margin blade. However, in order to stabilize the particle size of the polymer beads after polymerization and prevent the amount of monomers remaining in the beads from becoming too large, the above-mentioned polymerization system is emulsified in the pre-emulsification step to obtain the polymerization component. It is preferable to make fine droplets.

【0025】

In the pre-emulsification step, the polymer droplets once microdropped do not coalesce to cause droplet growth, and the particle size of the polymer beads after polymerization is set to the desired particle size. It is necessary to set the composition and concentration conditions of the dispersion stabilizer and set the emulsification conditions by the homogenizer. For example, under the above-mentioned dispersion stabilizer type and concentration conditions, the homogenizer conditions are in the range of 3,000 to 15,000 rpm and 5 to 20 minutes, preferably 4,000 to 12,000 rpm and 7 to 15 minutes. Is the range of.

【0026】

The polymerization system pre-emulsified as described above is transferred to a polymerization can, and suspension polymerization is carried out at a temperature of 60 to 100 ° C. and a time of 3 to 8 hours to obtain an acrylic having an average particle size of 0.1 to 30 μm containing titanium dioxide. An aqueous dispersion of polymer beads can be obtained. Thus, a polymer bead dispersion can be obtained. When the polymer beads are used, the obtained polymer bead dispersion is obtained when the outdoor paint to which the polymer beads are added is water-based. Can be used as it is, but if weather resistance is highly required, the obtained polymer bead dispersion can be filtered by a well-known method and used in a water-containing state obtained by washing. It can also be used in dehydrated cakes with adjusted water content. When the outdoor paint to which the polymer beads are added is a solvent-based paint, powdered beads or the like obtained by further drying the dehydrated cake and crushing the agglomerated polymer beads is used.

【0027】

The particle size of the titanium dioxide-containing suspended polymer beads constituting the outdoor coating composition of the present invention is preferably in the range of 0.1 to 30 μm, but is obtained from the outdoor coating composition containing the polymer beads. If the coating to be coated requires a glossy appearance, it is more preferably in the range of 1 to 10 μm, and if a matte appearance is required, a hiding property and a low gloss appearance are required. Therefore, it is preferable to use beads in the range of 1 to 10 μm (ensure concealment) and beads in the range of 10 to 30 μm in combination.

【0028】

The outdoor coating composition targeted by the present invention includes any known coating composition used for outdoor applications, and to name a representative, the binder component forming the coating film is a polyester-based condensation. The main components are a body, a polyacrylic polymer, a polyacrylic silicone polymer, a silicone resin, a fluorine-containing polymer, an inorganic binder and the like, and there are water-dilutable and solvent-dilutable ones. Further, as the curing system, there are a wide range of systems from normal temperature drying to baking drying system such as medium volatilization drying type, isocyanate cross-linking system, aminoplast cross-linking system, oxylan ring cross-linking system, and alkoxysilane group condensation system.

【0029】

In addition to the titanium dioxide-containing suspended polymer beads used in the present invention as the titanium dioxide pigment, it is possible to use a wide range of other coloring pigments used for outdoor applications in combination, which is a representative with good weather resistance. Typical coloring pigments include various inorganic pigments such as carbon black, iron oxide, and composite oxides (nickel / titanium, chromium / titanium, bismus / vanadium), quinacridone, diketopyrrolopyrrole, and benzimidazolone. , Isoindolinone, anthrapyrimidine, phthalocyanine, threne, dioxazine and other various organic pigments.

【0030】

It is preferable that the titanium dioxide pigment is not contained except for those contained in the polymer beads, but the compounding weight of titanium from other than the polymer beads is 40% by weight or less of the total titanium oxide compounding amount. W₁, Coating film forming binder solid content weight W₂As the formula 0.2 W₁/ (W₁+ W₂) It is possible to use titanium from other than polymer beads for the purpose of cost reduction and improvement of concealment as long as the weather resistance is not deteriorated.

【0031】

In addition, various extender pigments such as talc, mica, calcium carbonate, barium sulfate, silicon oxide, aluminum oxide, and kaolin are mixed and used within 10% by weight based on the solid content weight within a range that does not deteriorate the weather resistance of the coating film. It is also possible to do. Further, other plastic beads, fibrous pigments, pearl pigments, metal powders, ceramic powders and the like can also be used in combination.

【0032】

Further, as other additives and modifiers, precipitation inhibitors, surface modifiers, reaction accelerators, ultraviolet absorbers, pigment dispersants and the like can be appropriately used, and these are 0.1 to 0.1 to total solid content. It can be used in the range of 5.0% by weight. The outdoor coating composition thus obtained can be coated by a known coating method, for example, a brush, a spray, a flow coater, a roll coater, an electrostatic coating, a dip coating or the like.

【0033】

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. <Preparation of titanium dioxide paste> 520 g of toluene and 55 g of n-butanol were charged in a reaction vessel equipped with a reflux cooler and a stirrer, and the temperature was raised to 80 ° C. Then, methyl methacrylate 300 g, cyclohexyl methacrylate 90 g, and methacrylic acid A mixture of 30 g of 2-hydroxyethyl, 50 g of acrylic acid and 7.5 g of azobisisobutyvaleronitrile was added dropwise over 2 hours, 2.5 g of azobisisobutyvaleronitrile was further added, the temperature was raised to 85 ° C, and the temperature was raised to 85 ° C. over 4 hours. The reaction was carried out, and then the mixture was cooled and taken out to obtain an acrylic copolymer resin varnish having a non-volatile content of 42.5% by weight and a weight average molecular weight of 73000. Next, in a ball mill with an internal volume of 3 liters Titanium dioxide 1005g (Made by Ishihara Sangyo Co., Ltd., trade name Typake CR95) Acrylic copolymer resin varnish obtained above 300g Methyl methacrylate 195g , Add 1.5 liters of alumina balls with a diameter of 30 mm, knead and disperse over 48 hours, observe and confirm with an electron microscope that the average particle size of titanium dioxide particles is in the range of 220 to 290 nm, and titanium dioxide. I took out the paste.

【0034】

<Preparation of titanium dioxide-containing acrylic polymer beads> 75 parts by weight of the above titanium dioxide paste Methyl methacrylate 32 parts by weight Ethylene glycol dimethacrylate 2.2 parts by weight Lauryl peroxide 0.22 parts by weight 0.22 parts by weight of benzoyl peroxide Was mixed and dissolved to prepare solution X. Also, 300 parts by weight of ion-exchanged water 1.5 parts by weight of polyvinyl alcohol 0.2 parts by weight of soda dodecylbenzene sulfonic acid Was mixed and dissolved to prepare solution Y1. In addition 300 parts by weight of ion-exchanged water 1.5 parts by weight of polyvinyl alcohol Was mixed and dissolved to prepare solution Y2.

【0035】

Next, the above solution X and solution Y1 were mixed, pre-emulsified at 13000 rpm for 10 minutes using a homogenizer, and immediately reacted at 80 ° C. for 6 hours to obtain a dispersion of titanium dioxide-containing acrylic polymer beads A. Got Similarly, the above solution X and solution Y2 are mixed, stirred at 3500 rpm for 10 minutes using a homogenizer, pre-emulsified, and immediately reacted at 80 ° C. for 6 hours to produce a titanium dioxide-containing acrylic polymer. A dispersion of beads B was obtained.

【0036】

The dispersions of the titanium dioxide-containing acrylic polymer beads A and B obtained above were centrifuged. The cake layer formed on the surface of the filter cloth is showered with warm water at 50 ° C., washed, and then centrifuged. This operation is repeated 3 times to wash the surface of the acrylic polymer beads. A dehydrated cake (moisture content: 30-35% by weight) was obtained. Then, each dehydrated cake was dried under reduced pressure. The drying conditions were an initial temperature of 40 to 50 ° C and a decompression degree of 80 mmHg, a late temperature of 110 ° C and a decompression degree of 25 mmHg, and a drying time of 30 minutes. After crushing each dried product with a crusher, large particles and foreign substances were removed by a vibrating sieve to obtain powdered beads of the target titanium dioxide-containing acrylic polymer beads A and B. The average particle size of the titanium dioxide-containing acrylic polymer beads A was 3.5 μm, and the average particle size of the titanium dioxide-containing acrylic polymer beads B was 24.0 μm.

【0037】

<Examples 1 to 5 and Comparative Examples 1 to 5> Various components shown in Table 1 were blended in an amount shown in Table 1 (numerical values indicate parts by weight of each component) to prepare an outdoor coating composition. .. Each component used was as follows. The titanium dioxide-containing acrylic polymer beads A are prepared as described above. The titanium dioxide-containing acrylic polymer beads B are prepared as described above. Titanium dioxide is a trade name of Taipaque CR95 manufactured by Ishihara Sangyo Co., Ltd.

【0038】

The acrylic copolymer varnish is a trade name of Acrydic A801 manufactured by Dainippon Ink and Chemicals Co., Ltd., which has the following characteristics. Non-volatile content: 50 ± 2% by weight, Gardner Bubble Viscosity: P ~ T, Acid value: less than 3 (varnish), OH value: 50 ± 2 (varnish).

【0039】

The acrylic silicone copolymer varnish is a trade name Zemrack YC3623 manufactured by Kaneka Chemical Industry Co., Ltd., which has the following characteristics. Non-volatile content: 52 ± 2% by weight, Viscosity: 1100 ± 300 mPa · s (23 ° C).

【0040】

The fluorine-containing copolymer varnish is Lumiflon LF400, a trade name manufactured by Asahi Glass Co., Ltd., which has the following characteristics. Non-volatile content: 50 ± 1% by weight, Viscosity: 5.0 ± 1.0 St (25 ° C), Acid value: 2-3, OH value: 46 ± 1.5 (varnish).

【0041】

The fluorine-containing copolymer emulsion varnish is Lumiflon FE3000, a trade name manufactured by Asahi Glass Co., Ltd., which has the following characteristics. Non-volatile content: 50 ± 1% by weight, OH value: 32 ± 1.5 (varnish). As a matting agent, silicon dioxide, trade name Irisia 445 manufactured by Fuji Serial Chemical Co., Ltd. was used.

【0042】

As a thickener, hydroxyethyl cellulose, trade name Natrazole 250HR manufactured by Hercules, was used. As the dispersant, Neoneugen 140A, which is a polyoxyethylene alkyl phenyl ether (nonionic surfactant) manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., was used. As a defoaming agent, the trade name Nopco 8034 manufactured by San Nopco Co., Ltd., which is a mineral oil-based special nonionic surfactant, was used.

【0043】

Kaneka Zemrack ZW806Z, which is a trade name manufactured by Kanebuchi Chemical Industry Co., Ltd., was used as a water supplement. Coronate HX is a trade name of hexamethylene diisocyanate trimmer manufactured by Nippon Polyurethane Industry Co., Ltd. The tin-based catalyst is a catalyst for acrylic silicone, and the trade name Kaneka Zemrack ZT118Z manufactured by Kanebuchi Chemical Industry Co., Ltd. was used.

【0044】

[table 1]

<img file="JPH11228875A_D0001.tif" />【0045】

&lt;Creation of test plate&gt; 10 weights of acrylic copolymer consisting of methyl methacrylate / butyl acrylate / 2-hydroxyethyl methacrylate = 70/20/10 (weight ratio) in ceramic siding [(base plate siding) JIS-A5422] Coating viscosity 17-18 seconds consisting of 7 parts by weight of hexamethylene diisocyanate trimethylolpropane adduct, 15 parts by weight of titanium white, 8 parts by weight of kaolin, 4 parts by weight of barium sulfate, 20 parts by weight of butyl acetate, and 28 parts by weight of xylene. The undercoat coating composition of FC # 4 was airless spray coated. The coating amount is 100 ± 10 g / m²It was (wet coating amount). Then, it was dried at 100 ° C. for 10 minutes.

【0046】

The coating compositions of Examples 1 to 5 and Comparative Examples 1 to 5 having a coating viscosity of 20 to 22 seconds / FC # 4 having the compositions shown in Table 1 were airless spray-coated on the dried undercoat film. The coating amount is 120 ~ 130g / m²It was (wet coating amount). Then, it was dried at 80 ° C. for 30 minutes. Then, after storing at room temperature for 1 week, it was subjected to the following various tests.

【0047】

&lt;Test method&gt; Adhesion Twenty-five gobans were formed by making 4 mm pitch gobans on the coated plate, cellophane tape was attached to the surface, and the number of remaining gobans was counted by rapidly peeling off and evaluated according to the following criteria. : The number of remaining Goban eyes is 23 or more, : The number of remaining Goban eyes is 15 to 22, ×: The number of remaining Goban eyes is 14 or less.

【0048】

·hardness It was evaluated as the pencil hardness measured according to JIS-K-5400. Warm water resistance The state of the coating film after immersing the test piece in warm water at 60 ° C. for 24 hours was visually evaluated according to the following criteria. : No change, : There is a slight change such as whitening, ×: Large changes such as whitening.

【0049】

Specular reflectance Measured according to JIS-K-5400. Sunshine weather meter (test time is shown in Table 2) It was evaluated according to the following criteria. : There is no change in the appearance of the coating film, and the gloss retention rate is 90% or more. Δ: There is a slight change in the appearance of the coating film, and the gloss retention rate is 70% or more. ×: The appearance of the coating film changes significantly, and the gloss retention rate is 50% or more. The results of the above various tests are as shown in Table 2.

【0050】

[Table 2]

<img file="JPH11228875A_D0002.tif" />【0051】

[Effect of the invention]

The outdoor coating composition of the present invention contains a titanium dioxide pigment as a suspension polymer bead containing titanium dioxide, and the photocatalytic activity of the titanium dioxide pigment is sufficiently suppressed, so that the coating film exhibits sufficient weather resistance. A film can be formed.