JP2003206433A - Method for preventing corrosion of weather-resistant steel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for preventing corrosion of a weather-resistant steel in saved process by which rust-proofing property and weather resistance are retained for a long period and the steel is arbitrarily colored. <P>SOLUTION: This method for preventing corrosion of weather-resistant steel comprises forming, in 50-90 μm dried coat thickness, a colored organic-inorganic composite top coat having ≥805% gloss retention ratio after 300 hrs accelerated weathering test sunshine weather meter irradiation and comprising (1) an organic-inorganic composite resin composed of a fluororesin, epoxy rein or (meth)acrylic resin having a hydrolyzable silyl group and an organosilane represented by the general formula: R<SP>1</SP><SB>n</SB>Si(OR<SP>2</SP>)<SB>4-n</SB>[wherein R<SP>1</SP>is a 1-8C organic group; R<SP>2</SP>is a 1-5C alkyl group; n is 1 or 2] and/or its partially hydrolyzed condensate, (2) a coloring agent and (3) a pollution-free rustproof pigment on the surface of a weather-resistant steel. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel method for coating weather resistant steel, and more specifically, it prevents flow rust (red rust) of weather resistant steel and makes it possible to impart various colors in harmony with the environment. Further, the present invention relates to a corrosion-resistant method for weather-resistant steel, which imparts long-term weather resistance and rust-preventive properties in a further process-saving manner.

[0002]

2. Description of the Related Art Generally, carbon steel is often used for steel structures because of its low cost. However, in carbon steel, moisture in the air (rainfall, humidity, etc.) and oxygen come into contact with the surface of the steel material, and red rust occurs in a short period of time. As a method for preventing the generation of red rust, a method of applying a paint is generally used. In this method, it is common to apply a coating having good durability in order to reduce repainting as much as possible. For example, inorganic zinc rich paint coating → epoxy resin paint mist coat → epoxy resin paint base coat (2
→ Epoxy resin paint intermediate coating → Polyurethane resin paint Top coating is a typical steel coating system that has a durability of 15 years or more. This coating system has the advantage that it can maintain the aesthetic appearance with colors that are in harmony with the environment and maintain long-term rust prevention, but on the other hand, this coating system has a thick film thickness and requires 6 additional coatings, so Takes time and costs. Therefore, in recent years, cases of using weather resistant steel having good corrosion resistance for steel structures have been increasing.

Weather-resistant steels are generally P, Cu, Cr, N.
It is a low alloy steel to which elements such as i have been added. This steel material forms a rust that protects against corrosion in the open air for more than a dozen years (hereinafter referred to as "protective rust"), and eliminates the need for rust preventive processing thereafter, so-called maintenance-free characteristics. have. The protective action against this corrosion is to control rust with so-called rust, and rust is mainly composed of amorphous iron oxyhydroxide containing a large amount of crystal water, which is a protective rust that is dense and has good adhesion. It is believed to contribute to formation.

[0004]

However, if the weather-resistant steel material is used without any treatment, floating rust such as red rust or yellow rust or flow rust occurs during the period until protective rust is formed. Therefore, not only is it unfavorable in appearance, but it is also a cause of pollution of the surrounding environment.
Further, in the conventional example, there is a surface treatment method by painting to obtain protective rust on the surface of weather resistant steel, but it still takes a long period of several years until protective rust is formed, during which the coating film itself It causes problems such as whitening, blistering, and peeling. Also, in order to make the generated rust inconspicuous,
The color tone was unified to rust color, and no consideration was given to giving various colors in harmony with the environment, such as painting on carbon steel.

The existing weather-resistant steel in which the generation of red rust or yellow rust has become remarkable is left as it is, and is left until it is formed with protective rust, or when repairing, usually after completely removing the rust, It was common to apply organic zinc rich paint → epoxy resin paint undercoating → epoxy resin paint intermediate coating → topcoating paint 4 to 5 times, but there were many coating processes, and there was a problem that it took time and cost. .

[0006]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the inventors of the present invention applied a top coat paint containing a resin and a colorant having good weather resistance to a weather resistant steel surface, The present invention has completed a process-saving corrosion-resistant method for weather-resistant steel, which maintains weather resistance for a long time and enables arbitrary coloring. That is, the present invention provides (1) (a) on the weather resistant steel surface.
A fluororesin, an epoxy resin or a (meth) acrylic resin having a hydrolyzable silyl group, and (b) a general formula, R ¹ _n Si (OR ² ) _4-n [wherein R ¹ has 1 to 8 carbon atoms] R ² is an organic group of
It is an alkyl group having 1 to 5 carbon atoms, and n is 1 or 2. ] An organic-inorganic composite resin consisting of an organosilane and / or a partial hydrolyzed condensate thereof represented by: (2) a colorant, and (3) a pollution-free rust preventive pigment, and an accelerated weather resistance test sunshine The present invention relates to a corrosion-resistant method for weather-resistant steel, which comprises forming a colored organic-inorganic composite top coating film having a gloss retention rate of 80% or more after 300 hours of weather meter irradiation with a dry film thickness of 50 to 90 µm.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. The weather-resistant steel used in the present invention is called SPA material or SMA material, and is defined in JIS G3141, and if rust or the like is attached, it is blasted or pickled as pretreatment. Is preferred. Next, the colored organic-inorganic composite top coating composition for forming the colored organic-inorganic composite top coating film formed in the present invention will be described. Colored organic-inorganic composite topcoat paint is an organic-inorganic composite resin, a colorant, a pollution-free rust preventive pigment, and a solvent, if necessary, a curing catalyst, a silane coupling agent, a dispersant, and an ultraviolet absorber. It is composed of various additives such as agents, antibacterial agents and cissing prevention agents. The form of the paint may be solvent-based, water-based, or solvent-free.

As the organic-inorganic composite resin (binder) which constitutes the colored organic-inorganic composite top coating composition, it is necessary to use a binder having good weather resistance. That is, the gloss retention after 300 hours of irradiation of the accelerated weather resistance test sunshine weather meter is 80% or more, preferably 85% or more (however,
The upper limit should be, for example, 90%) which is the resin that forms the topcoat. When the gloss retention is less than 80%, whitening, blistering, peeling, etc. occur in the coating film, which is not preferable. Accelerated weather resistance test The sunshine weather meter is a sunshine carbon arc lamp-type accelerated weather resistance tester that correlates with actual outdoor exposure specified by JIS K5400, and the gloss retention rate is 60 degrees specified by JIS K5400. It is the degree of gloss remaining calculated from the specular gloss by the following formula. Gloss retention = (Sunshine weather meter irradiation 30
0 hour gloss) x 100 / initial gloss (%)

The binder used in the colored organic-inorganic composite top coating is a fluororesin having a hydrolyzable silyl group, an epoxy resin or a (meth) acrylic resin (a), and an organosilane or an organosilane represented by the following formula. It consists of a partially hydrolyzed condensate of silane (b). Formula _{^{(1) R 1 n Si (}} OR 2) in _4-n [wherein, R ¹ is an organic group having 1 to 8 carbon atoms, R ² is
It is an alkyl group having 1 to 5 carbon atoms, and n is 1 or 2. In the above formula, examples of the organic group as R ¹ include an alkyl group, a cycloalkyl group, an aryl group, a vinyl group and the like. Here, as the alkyl group,
It may be linear or branched. As an alkyl group,
For example, methyl group, ethyl group, n-propyl group, i-
Examples thereof include alkyl groups such as propyl group, n-butyl group, i-butyl group, s-butyl group, t-butyl group, pentyl group, hexyl group, heptyl group and octyl group. Preferred alkyl groups have 1 to 4 carbon atoms.

Preferred examples of the cycloalkyl group include cyclohexyl group, cycloheptyl group, cyclooctyl group and the like. As the aryl group, for example,
Preferable examples include a phenyl group and a naphthyl group. These functional groups may optionally have a substituent. Preferable examples of such a substituent include a halogen atom (eg, chlorine atom, bromine atom, fluorine atom, etc.), (meth) acryloyl group, mercapto group, alicyclic group and the like. The alkyl group as R ² may be linear or branched. Examples of such an alkyl group include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, an s-butyl group,
Examples thereof include a t-butyl group and a pentyl group, and a preferable alkyl group has a carbon number of 1 to 2.

Fluorine resin having a hydrolyzable silyl group,
The epoxy resin or the (meth) acrylic resin is a fluororesin, an epoxy resin, or a (meth) acrylic resin which is generally used as a resin for a coating, in which a hydrolyzable silyl group is introduced. As a method of introducing a hydrolyzable silyl group into a fluororesin, an epoxy resin or a (meth) acrylic resin, (1) a hydrolyzable resin can be used together with a monomer for preparing the fluororesin, the epoxy resin or the (meth) acrylic resin. A method of preparing a monomer having a silyl group in combination, or (2) having a fluororesin, an epoxy resin or a (meth) acrylic resin having a functional group, and a functional group reactive with the functional group and a hydrolyzable silyl group. Examples thereof include a method of preparing by reacting with a compound, but the method is not limited to these methods.

In the case of (2) above, a fluororesin,
The relationship between the functional group contained in the epoxy resin or the (meth) acrylic resin and the functional group that reacts with the functional group is as follows. For example, if one functional group is an epoxy group,
The other functional group that reacts with it is a mercapto group,
Amino group, epoxy group, isocyanate group,
If one functional group is a carboxyl group, the other functional group that reacts with it is an amino group, an epoxy group, an isocyanate group, and if one functional group is an amino group, the other that reacts with it. Examples of the functional group include an epoxy group and an isocyanate group. If one functional group is a hydroxyl group, the other functional group that reacts with the hydroxyl group is an isocyanate group, an alkoxy group, or a phenoxy group.

The fluororesin having a hydrolyzable silyl group can be prepared, for example, by using a monomer used for preparing the fluororesin together with a polymerizable monomer having a hydrolyzable silyl group. Examples of the monomer used for preparing the fluororesin include vinyl fluoride, vinylidene fluoride, trifluoroethylene, tetrafluoroethylene, bromotrifluoroethylene, chlorotrifluoroethylene, pentafluoropropylene and hexafluoropropylene. , (Per) fluoroalkyl trifluorovinyl ether [(per) fluoroalkyl group having 1 to 18 carbon atoms is preferable. ] And the like can be preferably cited as typical ones. Of these, vinyl fluoride, vinylidene fluoride,
It is preferable to use at least one selected from the group consisting of trifluoroethylene, tetrafluoroethylene, chlorotrifluoroethylene, hexafluoropropylene, and (per) fluoro (C ₃ -C ₄ ) alkyltrifluorovinyl ether.

Suitable examples of the monomer having a hydrolyzable silyl group include vinyl compounds having a hydrolyzable silyl group. Examples of such a monomer include γ- (meth) acryloxypropyltrimethoxysilane, γ- (meth) acryloxypropyltriethoxysilane, β- (meth) acryloxyethyltrimethoxysilane, β- (meth). Acryloxyethyltriethoxysilane, γ- (meth) acryloxypropylmethyldimethoxysilane, γ- (meth) acryloxypropylmethyldiethoxysilane, γ- (meth) acryloxypropylmethyldipropoxysilane, γ- (meth) Examples thereof include acryloxybutylphenyldimethoxysilane and γ- (meth) acryloxypropyldiethylmethoxysilane. The fluororesin having a hydrolyzable silyl group can be used alone or as a mixture of two or more kinds.

The epoxy resin having a hydrolyzable silyl group is obtained by reacting a compound having a hydrolyzable silyl group with a mercapto group which reacts with the epoxy group of the epoxy resin, an amino group, an epoxy group or an isocyanate group. Can be prepared. As a compound containing a mercapto group, an amino group, an epoxy group, or an isocyanate group, and a hydrolyzable silyl group,
The hydrolyzable silyl group-containing compound having the following formula (2) can be preferably mentioned. Formula _{(2) ((X) a} -R 1) n Si (OR 2) in _4-n [wherein, R ¹ is an organic group having 1 to 8 carbon atoms, R ² is
It is an alkyl group having 1 to 5 carbon atoms, X is a functional group such as a mercapto group, an amino group, an epoxy group, or an isocyanate group, a is 1 or 2, and n is 1 or 2. . Here, the meanings of R ¹ and R ² are the same as in the case of the formula (1). Examples of such a compound having a hydrolyzable silyl group include γ-mercaptopropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ.
-Isocyanatopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-aminopropyltriethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-isocyanatopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane , Γ-aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-isocyanatopropyltrimethoxysilane, β-mercaptoethyltrimethoxysilane, β-aminoethyltrimethoxysilane, β-glycidoxyethyl Trimethoxysilane, β
-Isocyanatoethyl trimethoxysilane etc. can be mentioned suitably.

The epoxy resin used for introducing the hydrolyzable silyl group is, for example, bisphenol A.
Type epoxy resin, bisphenol F type epoxy resin,
Preferable examples include phenol novolac type epoxy resin, alkyl ether type epoxy resin, hydrogenated bisphenol A type epoxy resin and the like. The epoxy resin having a hydrolyzable silyl group can be used alone or as a mixture of two or more kinds. The (meth) acrylic resin having a hydrolyzable silyl group should be prepared, for example, by combining a monomer used to prepare the (meth) acrylic resin with a polymerizable monomer having a hydrolyzable silyl group. You can Examples of the monomer used to prepare the (meth) acrylic resin include:
Methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, (meth) acrylic acid 2
-(Meth) acrylic acid esters such as ethylhexyl and cyclohexyl (meth) acrylate, and (meth) acrylic acid such as (meth) acrylic acid or esters thereof are used. As the polymerizable monomer having a hydrolyzable silyl group, for example, a polymerizable monomer having a hydrolyzable silyl group used in the preparation of a fluororesin having a hydrolyzable silyl group can be used.

In the preparation of the (meth) acrylic resin having a hydrolyzable silyl group, the (meth) acrylic monomer used in the preparation of the (meth) acrylic resin is used together with another polymerizable monomer such as itacone. Acids, carboxylic acids such as fumaric acid and acid anhydrides such as maleic anhydride, epoxy compounds such as glycidyl (meth) acrylate, acrylonitrile, styrene, α-methylstyrene, vinyl acetate, vinyl propionate, etc. may be used in combination. it can. Furthermore, by using allyl (meth) acrylate, diallyl phthalate or the like in the preparation of the (meth) acrylic resin, a carbon-carbon double bond for the hydrosilylation reaction is introduced into the (meth) acrylic resin. can do. The (meth) acrylic resin having a hydrolyzable silyl group can be used alone or as a mixture of two or more kinds.

A fluororesin having a hydrolyzable silyl group,
The epoxy resin or the (meth) acrylic resin is, for example, 5 to 80 mass% based on the total mass of the organic-inorganic composite resin,
Preferably, it is suitable to use in an amount of 15 to 60% by mass. Specific examples of the acrylic resin containing a hydrolyzable silyl group include Kaneka Zemulac manufactured by Kanegafuchi Chemical Co., Ltd. as a commercially available product.

The colored organic-inorganic composite resin of the present invention comprises the above-mentioned fluororesin, epoxy resin or (meth) acrylic resin having a hydrolyzable silyl group, and the general formula (3), R ¹ _n Si (OR ² ) _{4- n} wherein, R ¹ is an organic group having 1 to 8 carbon atoms, R ² is
It is an alkyl group having 1 to 5 carbon atoms, and n is 1 or 2. ] Or a partially hydrolyzed condensate of the organosilane. In the above formula, the specific contents of R ¹ and R ² are the same as in the case of formula (1).

Specific examples of the organosilane represented by the above formula (3) include, for example, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane,
Ethyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, i-propyltrimethoxysilane, i-propyltriethoxysilane, γ-chloropropyltrimethoxysilane, γ-chloropropyltriethoxysilane, vinyl Trimethoxysilane, vinyltriethoxysilane, 3,3,3-trifluoropropyltrimethoxysilane, 3,3,3-trifluoropropyltriethoxysilane, cyclohexyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ -Methacryloxypropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane,
Examples include phenyltrimethoxysilane, phenyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, methylphenyldimethoxysilane, and dimethyldipropoxysilane. Are more preferably methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, and dimethyldimethoxysilane.

The partially hydrolyzed condensate of organosilane is
The organosilane is partially hydrolyzed and condensed. In this case, the organosilane can be used alone or as a mixture of two or more kinds. The partially hydrolyzed condensate of organosilane has a polystyrene-reduced weight average molecular weight of, for example, 300 to 5,000, preferably
Those of 500 to 4200 are suitable. By using such a condensate, a coating film having good storage stability and good adhesion can be obtained. A specific example of such a condensate is a commercially available S manufactured by Toray Dow Corning.
R2402, DC3037, DC3074, Shin-Etsu Chemical Co., Ltd.'s KR-211, KR-212, KR-21
3, KR-214, KR-216, KR-218, TSR-145 and TSR-160 manufactured by Toshiba Silicone Co., Ltd.
Preferable examples include TSR-165 and YR-3187. The hydrolysis-condensation reaction is carried out by mixing organosilane with water, optionally in the presence of a catalyst, at 40 to 80 ° C., preferably 45.
A method of reacting at ~ 65 ° C while stirring for 2 to 10 hours is suitable, but not limited to this method.

As the above reaction catalyst, trialkoxyborane such as trimethoxyborane and triethoxyborane;
Zirconium chelate compounds such as tri-n-butoxyethylacetoacetate zirconium, di-n-butoxydi (ethylacetoacetate) zirconium, tetrakis (ethylacetoacetate) zirconium, diisopropoxybis (acetylacetate) titanium, diisopropoxybis ( Examples thereof include titanium chelate compounds such as ethylacetoacetate) titanium, and organometallic compounds such as aluminum chelate compounds such as monoacetylacetate bis (ethylacetoacetate) aluminum and diisopropoxyethylacetoacetate aluminum.
Organosilane or organosilane partially hydrolyzed condensate, based on the total weight of the organic-inorganic composite resin, for example,
It is suitable to use in an amount of 20 to 95% by weight, preferably 40 to 85% by weight.

As the colorant to be blended in the colored organic-inorganic composite top coating composition of the present invention, those used for coloring in the field of coating composition can be appropriately used without any particular limitation. Specific examples of such colorants include titanium dioxide, white pigments such as zinc oxide, carbon black, black pigments such as graphite, molybdate orange, permanent carmine, red pigments such as quinacridone red, and quinophthalene yellow. Representative examples include yellow pigments such as permanent yellow, green pigments such as phthalocyanine green and phthalocyanine blue, and pigments of each color such as blue pigment. Further, an extender pigment may be used in combination.
The blending amount of the color pigment is, for example, 0.1 to 70% by mass, preferably 1 to 5 based on the mass of the organic-inorganic composite resin.
It is suitable that it is 0% by mass.

Examples of pollution-free rust-preventive pigments used in the colored organic-inorganic composite top coating include, for example, aluminum phosphate, aluminum tripolyphosphate, zinc phosphate, zinc phosphite, potassium phosphite, calcium phosphite, Aluminum phosphate, zinc calcium phosphate, zinc aluminum phosphate, zinc molybdate, zinc phosphomolybdate, aluminum phosphomolybdate, calcium molybdate, and anti-rust pigments such as hydrocalumite,
These are used alone or as a mixture of two or more.
However, chromium-based and lead-based rust preventive pigments are not preferable from the viewpoint of toxicity.

The pollution-free rust preventive pigment is, for example, from 1 to 80% by mass, preferably from the mass of the organic-inorganic composite resin.
It is preferable to blend in an amount of 5 to 60% by mass. If the amount of the pollution-free rust preventive pigment is less than 1 part by mass, the rust preventive property tends to be insufficient. On the other hand, when the amount exceeds 80 parts by mass, the stability of the coating tends to deteriorate. The colored organic-inorganic composite top-coat paint is suitably applied in a dry film thickness of 50 to 90 μm, preferably 60 to 80 μm. When the dry film thickness is less than 50 μm, the hiding property and weather resistance are insufficient. On the other hand, if it exceeds 90 μm, foaming and curing failure are likely to occur, and when coating on a vertical surface, problems such as dripping of the coating material occur.

Next, the method of coating the weather resistant steel will be described. If floating rust is generated on the surface of the weather resistant steel used, remove only the floating rust with a wire brush. It should be noted that rust such as red rust and yellow rust adhered to the weather resistant steel is not a problem, but floating rust causes the coating film to be easily peeled off together with floating rust, and it is necessary to remove it as a pretreatment for that. Next, the above organic-inorganic composite top coating composition is applied to weather resistant steel by means of brush, spray, roller or the like to give a dry film thickness of 50 to 90 μm.
And the film is dried naturally or forcedly dried at a temperature of 100 ° C. or lower to form a film.

[0027]

EXAMPLES The present invention will be described in more detail below with reference to examples. In the examples, "parts" and "%" are based on mass unless otherwise specified. Synthesis Example 1 A reactor equipped with a reflux condenser and a stirrer was used, and a fluorine resin containing a hydroxyl group (trade name: Zeffle GK manufactured by Daikin Industries, Ltd.
550, solid content 60%) 190 g were charged, and 42 g of γ-isocyanatopropylmethyldimethoxysilane and 0.05 g of dibutyltin dilaurate were added with stirring to 4
The mixture was stirred at 0 ° C. for 4 hours to synthesize a fluororesin (i) having a hydrolyzable silyl group having a solid content of 67%.

Synthesis Example 2 A reactor equipped with a reflux condenser and a stirrer was charged with 15 parts of propylene glycol mono-n-propyl ether and 10 parts of xylene, and an epoxy resin (Epicoat 828 manufactured by Yuka Shell Epoxy Co., epoxy equivalent) was charged. 195) 100 copies,
Partially hydrolyzed cocondensate of phenyltrimethoxysilane (trade name: DC3074 manufactured by Toray Dow Corning, solid content 100%) 30 parts, aluminum trimethoxide 0.
Charge 15 parts and stir at 100 ° C. for 4 hours to obtain a solid content of 60.
An epoxy resin (ii) having a% hydrolyzable silyl group was synthesized.

Synthesis Example 3 Xylene 55 was added to a reactor equipped with a reflux condenser and a stirrer.
And 40 parts of isobutanol were added and mixed, and then heated to 85 ° C. with stirring. Next, 50 parts of isobutyl methacrylate and 35 parts of 2-ethylhexyl methacrylate
Part, γ-methacryloxypropyltrimethoxysilane 1
A mixed solution of 5 parts and 1.5 parts of azobisisovaleronitrile was added dropwise at 85 ° C over 3 hours, then heated to 90 ° C and maintained for 2 hours to complete the reaction. An acrylic resin (iii) having a hydrolyzable silyl group having a solid content of 50% was synthesized.

Synthesis Example 4 A reactor equipped with a reflux condenser and a stirrer was charged with 15 parts of propylene glycol mono-n-propyl ether and 10 parts of xylene and 50 parts of γ-mercaptopropyltrimethoxysilane while stirring at room temperature. Partially hydrolyzed cocondensate of phenyltrimethoxysilane (DC3074 manufactured by Toray Dow Corning Co., Ltd .; solid content 100%)
And 30 parts of methyltrimethoxysilane were added and mixed, 9 parts of ion-exchanged water and 5 parts of isopropyl alcohol were added, and the mixture was reacted at 60 ° C. for 3 hours. Next, 0.5 part of triethoxyborane was added, and the mixture was further stirred at 60 ° C. for 3 hours to obtain a polyorganosiloxane (iv) having a solid content of 60% and an active hydrogen equivalent of 510 (varnish value).

Synthesis Example 5 A reactor equipped with a reflux condenser and a stirrer was charged with 20 parts of propylene glycol mono-n-propyl ether and 10 parts of xylene, and 40 parts of γ-mercaptopropyltrimethoxysilane and phenyl under stirring at room temperature. 20 parts of partially hydrolyzed cocondensate of trimethoxysilane (DC3074 manufactured by Toray Dow Corning Co., Ltd .; solid content 100%),
30 parts of phenyltrimethoxysilane partially hydrolyzed cocondensate (DC3037 manufactured by Toray Dow Corning Co., Ltd .; solid content 100%) and 1 part of methyltrimethoxysilane
After 0 parts were added and mixed, 7.2 parts of ion-exchanged water and 5 parts of isopropyl alcohol were added and reacted at 60 ° C. for 3 hours. Then add 0.5 parts of triethoxyborane and add another 6 parts.
Stirring was continued at 0 ° C. for 3 hours to obtain a polyorganosiloxane (v) having a solid content of 60% and an active hydrogen equivalent of 680 (varnish value).

Preparation of Resin Solution Used in Examples 1 to 5 The resin components (i) to (v) obtained in the above synthesis examples were heated and stirred at 50 ° C. for 2 hours, and then the component (vi) was expressed at 20 ° C. The mixture was mixed as shown in 2 and stirred until uniform to obtain a resin solution.

[Table 1] <Table 1> Composition of coating resin solution (unit: part)

Example 1 Average surface roughness 30 μm after alumina blast treatment
And having a size of 3 × 100 × 300 (mm), JIS
On the surface of weather resistant steel (SMA400) specified in G3141,
The following colored organic-inorganic composite top-coat paint was applied once to a dry film thickness of 60 μm, the back and side surfaces were sealed with an epoxy resin paint, and naturally dried for 7 days. The coated steel was evaluated for weather resistance and corrosion resistance, and the results are shown in Table 2 below. [Topcoat paint] Resin solution 1 shown in Table 1 (solid content 63%) 130.0 parts Aluminum tripolyphosphate 18.0 parts Quinacridone red 32.3 parts

Example 2 The same weathering steel (SMA40 as used in Example 1)
0) The following colored organic-inorganic composite top-coat paint was applied once to the surface so that the dry film thickness was 60 μm, the back and side surfaces were sealed with an epoxy resin paint, and naturally dried for 7 days. The coated steel was evaluated for weather resistance and corrosion resistance, and the results are shown in Table 2 below. [Topcoat paint] Resin solution 2 shown in Table 1 (60% solid content) 125.0 parts Cyanamide zinc 21.5 parts Quinacridone red 32.3 parts

Example 3 The same weathering steel (SMA40 as used in Example 1)
0) The following colored organic-inorganic composite top coating composition was applied once to the surface so that the dry film thickness was 60 m, the back surface and the side surface were sealed with an epoxy resin coating, and naturally dried for 7 days. The coated steel was evaluated for weather resistance and corrosion resistance, and the results are shown in Table 2 below. [Topcoat paint] Resin solution 3 shown in Table 1 (solid content 56%) 125.0 parts Zinc phosphite 8.0 parts Quinophthalene yellow 32.0 parts

Example 4 3 × 100 exposed to the outdoors for 5 years without treatment and having floating rust
The surface of the weather resistant steel (SMA400) specified in JIS G 3141 of × 300 (mm) was lightly removed by floating rust with a wire brush, and then the colored organic-inorganic composite top coating used in Example 3 was dried. It was coated once to a thickness of 60 μm, the back and side surfaces were sealed with an epoxy resin coating, and naturally dried for 7 days. The coated steel was evaluated for weather resistance and corrosion resistance, and the results are shown in Table 2 below.

Example 5 3 × 100 having floating rust after being exposed outdoors for 5 years
The surface of the weather-resistant steel (SMA400) specified in JIS G 3141 of × 300 (mm) was lightly floated with a wire brush to remove rust, and the colored organic-inorganic composite top coating used in Example 1 was dried to obtain a dry film thickness. Of 60 μm was applied once, the back and side surfaces were sealed with an epoxy resin paint, and naturally dried for 7 days. The coated steel was evaluated for weather resistance and corrosion resistance, and the results are shown in Table 2 below.

Comparative Example 1 The same weathering steel as used in Example 1 (SMA40
0) The following colored organic-inorganic composite top-coat paint using an epoxy resin having no hydrolyzable silyl group is applied once on the surface so that the dry film thickness is 60 μm, and the back and side surfaces are sealed with the epoxy resin paint. It was naturally dried for 7 days. The coated steel was evaluated for weather resistance and corrosion resistance, and the results are shown in Table 2 below. [Topcoat paint] Epicoat 828 100.0 parts Quinacridone red 32.3 parts Daito Clar B1969 40.0 parts

Comparative Example 2 Weather resistance and corrosion resistance were evaluated without coating the weather resistant steel used in Example 1, and the results are shown in Table 2 below.

Comparative Example 3 The weather resistance steel used in Example 4 was evaluated for weather resistance and anticorrosion properties by removing floating rust with a wire brush and without coating at all. The results are shown in Table 2 below.

[0041]

[Table 2] <Table 2> Color, weather resistance, corrosion resistance and gloss retention
rate Note 1) Gloss retention (%) after 300 hours of sunshine weather meter Note 2) Outdoor exposure for 1 year Note 3) Salt spray test for 1000 hours

As is clear from Table 2, in Examples 1 to 5 of the present invention, the weather resistant steel could be colored in any color, and excellent weather resistance and corrosion resistance were obtained. On the other hand, in Comparative Example 1 in which the epoxy resin having no hydrolyzable silyl group was used, and in Comparative Example 2 and Comparative Example 3 without coating, red rust occurred. According to the method of the present invention, it is possible to prevent corrosion of weather-resistant steel, which retains rust resistance and weather resistance for a long period of time and allows arbitrary coloring, and which is a process-saving process.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C09D 183/04 C09D 183/04 (72) Inventor Toki Toru, 7-1414 Shimonagata, Nishinasuno-cho, Nasu-gun, Tochigi Prefecture −34 (72) Inventor Hiroharu Sasaki 7-14-14 Shimonagata, Nishinasuno-machi, Nasu-gun, Tochigi Prefecture 14-14-46 (72) Hiroyuki Tanabe 8-15 Asahi-cho, Nishinasuno-cho, Nasu-gun, Tochigi Prefecture 4J038 CD091 CD101 CD111 CD121 CD131 CD141 CG141 CL001 DB171 DL031 GA15 KA05 KA08 NA03 PC02

Claims (2)

[Claims] 1. A fluororesin, an epoxy resin or a (meth) acrylic resin having (1) (a) a hydrolyzable silyl group on the surface of weather resistant steel, (b) a general formula, R ¹ _n Si (OR ² ) _4-n [In the formula, R ¹ is an organic group having 1 to 8 carbon atoms, and R ² is
It is an alkyl group having 1 to 5 carbon atoms, and n is 1 or 2. ] An organic-inorganic composite resin consisting of an organosilane and / or a partial hydrolyzed condensate thereof represented by: (2) a colorant, and (3) a pollution-free rust preventive pigment, and an accelerated weather resistance test sunshine A method for preventing corrosion of weather-resistant steel, which comprises forming a colored organic-inorganic composite top coating film having a gloss retention rate of 80% or more after 300 hours of weather meter irradiation with a dry film thickness of 50 to 90 μm. 2. The anticorrosion method according to claim 1, wherein the weather resistant steel is a weather resistant steel in which only rust and floating rust remain.