JP2002129356A - Durable hot-dip galvanized steel and coating method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a durable hot-dip galvanized steel suitable for road materials or the like, because of a coating with a high adhesiveness, hardness, weather-resistance and the like, and with adequate wettability and superior pollution resistance thereon. SOLUTION: The hot-dip galvanized steel comprises a coating on the surface, which is formed out of a composition consisting of (a) the fourth grade ammonium silicate of 5-15 pts.wt. as SiO2, (b) an inorganic filler of 15-75 pts.wt., (c) a synthetic resin emulsion and/or a water-soluble synthetic resin of 2-12 pts.wt. as the synthetic resin, and (d) water and/or hydrophilic organic solvent for the rest.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a hot-dip galvanized steel material having hydrophilicity, air permeability, adhesion, weather resistance,
The present invention relates to durable hot-dip galvanized steel with a coating film with excellent hardness and stain resistance, and its coating method, and is particularly effective in preventing the deterioration of the landscape due to the adhesion of dirt to the surface of road materials in contaminated environments. It provides a simple means.

[0002]

2. Description of the Related Art Hot-dip galvanized steel is widely used for outdoor steel structures because of its excellent corrosion resistance. However, it is inevitable that white rust and the like are generated due to long-term outdoor exposure. Due to the severe environment, it is desired to form a film having excellent adhesion and weather resistance on the surface thereof to ensure long-term durability.

[0003] Hot-dip galvanized steel materials are also frequently used in road steel materials such as road signs and safety shelves. However, dirt due to soot and oil-based deposits in exhaust gas reduces the landscape and visibility. Therefore, antifouling measures are an important issue.

[0004] Conventionally, as a countermeasure against soiling of an outdoor structure, a method of forming a hydrophilic film on the surface of the structure to improve the cleaning property of the stain with rainwater has been mainly performed. As such a hydrophilic film, for example, a method is known in which a resin having an alkoxysilyl group is contained, and the alkoxysilyl group is hydrolyzed by a silanol group generated by hydrolysis. However, this method has a problem that it takes a long time to generate silanol groups and it takes several months to obtain sufficient hydrophilicity.

In recent years, it has been found that a film containing a photocatalyst has high hydrophilicity, and has been applied to various uses as an antifouling coating, and attempts to use it for antifouling of road materials have been proposed. (JP-A-9-78541, JP-A-9-310318, JP-A-10-37135, etc.).

However, in this method, since the photocatalyst itself is expensive and decomposes organic components, it is difficult to ensure the durability and rust prevention of the organic coating applied under the photocatalytic coating. There's a problem.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and is intended to prevent long-term occurrence of white rust, weather resistance and stain resistance, to improve surface hardness and to prevent rust. It is an object of the present invention to provide a durable hot-dip galvanized steel material capable of improving the strength and a coating method thereof.

[0008]

The durable hot-dip galvanized steel material of the present invention for solving the above-mentioned problems has a hot-dip galvanized steel material coated with a coating film having hydrophilicity, air permeability and high weather resistance. It is a durable hot-dip galvanized steel material characterized by the above.

The coating film comprises (a) 5 to 15 parts by weight of a quaternary ammonium silicate in terms of SiO ₂ , (b) 15 to 75 parts by weight of an inorganic filler, and (c) a synthetic resin emulsion. And / or 2 of water-soluble synthetic resin in terms of synthetic resin.
A composition comprising (d) water or / and a hydrophilic organic solvent (where (a) + (b) + (c) + (d) = 100 parts by weight). The above durable hot-dip galvanized steel material.

The inorganic filler in the composition may be a water-insoluble fine particle or short fiber metal oxide, metal hydroxide,
It is preferable that at least one selected from the group consisting of metal carbides, metal nitrides, metal carbonates and metals.

The method of coating a durable hot-dip galvanized steel material according to the present invention comprises applying the above composition to the surface of the hot-dip galvanized steel material at a solid content of 25 to 250 per square meter.
This is a method for coating a durable hot-dip galvanized steel material, which comprises applying gram and hardening it under normal temperature or low temperature heating.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The quaternary ammonium silicate (a) which is a component of the composition used in the present invention has the general formula (R ₃₎
N) ₂ O · nSiO ₂ (where R is an alkyl group having 1 or more carbon atoms and n is an integer of 1 or more).

(A) Specific examples of the quaternary ammonium silicate include dimethylethanolammonium silicate, monomethyltripropanolammonium silicate, dimethyldipropanolammonium silicate,
Liquid silicates such as monoethyltripropanol ammonium silicate can be used.

These (a) quaternary ammonium silicates are prepared by adding a quaternary ammonium hydroxide to an activated silica solution obtained by contacting a diluted water glass with a hydrogen-type cation exchange resin, It can be easily obtained by a method of concentrating to the maximum, or a method of reacting a quaternary ammonium hydroxide with a silica hydrosol.

Here, the quaternary ammonium hydroxide is
Usually, it is obtained by a method of adding an alkylene oxide to ammonia or amines, or a method of deionizing a quaternary amine salt with an anion exchange resin. Those containing a small amount of primary amines can also be used, and the quaternary ammonium silicate obtained using the same can also be used in the composition of the present invention.

In the present invention, the component (a) is used as a binder, which reacts with zinc of the base material and adheres strongly. This reaction is represented by the following reaction formulas (1) and (2).

[0017]

Embedded image In the above reaction formulas (1) and (2), R represents an alkyl group having 1 or more carbon atoms, and n = 1 to 3.

The coating film formed from the composition used in the present invention has an extremely good wettability, as shown in Examples described later. The main reason for this is that the component (a) may be used. Guessed. Generally, hydrated silicates have the property of condensing silanol groups by dehydration to form a three-dimensional structure. However, uncondensed silanol groups in ammonium silicate and / or ammonium silicate due to moisture in the atmosphere. It is considered that silanol groups generated by hydrolysis of the silicate enhance the hydrophilicity of the coating film.

As described above, in the present invention, by using (a) a quaternary ammonium silicate as a binder, the adhesion between the base material zinc and the coating film is improved, and the hydrophilicity of the coating film is improved. The feature is that the antifouling property (stain resistance) is increased by increasing the size.

In the present invention, the proportion of the component (a) is
To 100 parts by weight of component (d) (however, (a) is SiO ₂
Component amount not converted, and (c) is a component amount is not converted synthetic resin) in 5 to 15 parts by weight in terms of SiO _2. More preferably, it is 6 to 12 parts by weight.

(B) The inorganic filler is used in order to obtain a coating film having excellent weather resistance, to improve the rust-preventing power by making the coating film hydrophilic and air-permeable, and to provide various functionalities to the coating film. For example, it is used for imparting heat insulating property, heat dissipation property, antifungal property, deodorizing property and the like. The addition of the inorganic filler improves the hydrophilicity of the coating film, and also contributes to the improvement of the antifouling property.

(B) The inorganic filler is selected from the group consisting of metal oxides, metal hydroxides, metal carbides, metal nitrides, metal carbonates, and metals in the form of water-insoluble fine particles or short fibers. And the average particle diameter or average length is preferably 0.1 to 100 μm.
m, more preferably 0.1 to 20 μm.

(B) Specific examples of the inorganic filler include titanium oxide, iron oxide, zinc oxide, chromium oxide, and the like as coloring pigments.
Manganese oxide, cobalt oxide-aluminum, synthetic oxides such as copper oxide-nickel, silica as a volume pigment,
Alumina, kaolin, zircon, talc, calcium carbonate, magnesium silicate, silicon nitride, tin oxide, silicon carbide, carbon, zeolite, pearlite, potassium titanate whisker as functional filler, and metal powders such as nickel and stainless steel However, the present invention is not limited to these.

The amount of the inorganic filler (b) in the composition of the present invention is 15 to 75 parts by weight, preferably 25 to 60 parts by weight.

(C) The synthetic resin emulsion and / or the water-soluble synthetic resin are used as an adhesion aid, a coating density adjuster, and a softener. Specific examples of the synthetic resin emulsion include a vinyl acetate resin emulsion, an acrylic resin emulsion, an acrylic-styrene copolymer emulsion, a styrene-butadiene copolymer emulsion, an acrylic-modified urethane resin emulsion, and the like.
Examples of the water-soluble synthetic resin include, but are not limited to, a water-soluble melamine resin, a water-soluble acrylic resin, a water-soluble alkyd resin, and a water-soluble polybutadiene.

The amount of component (c) is 2 to 12 parts by weight, preferably 4 to 8 parts by weight, in terms of synthetic resin in the composition of the present invention.

(D) water and / or a hydrophilic organic solvent
Adjustment of viscosity and pot life of the composition of the present invention, further (b)
It is an essential component for dispersion of the inorganic filler. As the water, tap water, ion-exchanged water, distilled water, or the like can be used. The water also contains (a) a quaternary ammonium silicate and (c)
Water included in the synthetic resin emulsion or / and the water-soluble synthetic resin is also included.

The hydrophilic organic solvent is a solvent compatible with water, and specific examples thereof include alcohols such as ethanol, i-propanol, and methylcarbinol, and glycols such as ethylene glycol and propylene glycol. Can be

In the composition of the present invention, in addition to the above components (a) to (d), various surfactants, dispersants, thickeners, curing regulators, organic dyes and pigments, Additives may be included.

[0030]

EXAMPLES Three types of compositions A to C shown in Table 1 were prepared. These compositions are added to a stirring tank with the components (a) to (d),
Further, if necessary, the component (e) and / or other additives are added and lightly mixed, and then a high-speed stirrer (about 15.0
(00 rpm) for 10 minutes, and then filtered through a 100 mesh to prepare. The symbols of the component names in Table 1 represent the following.

(A) Quaternary ammonium silicate (a) -1: Amine silicate (NS-2 manufactured by Nippon Laboratories, Inc.)
5 (SiO ₂ concentration = about 25%)) (b) Inorganic filler (b) -1: Titanium oxide white (average particle size = 0.5 μm) (b) -2: Iron / manganese synthetic oxide tea (average Particle size = 0.
(B) -3: silicon dioxide (average particle size = 15 μm) (b) -4: calcium silicate (average particle size = 3 μm) (b) -5: potassium titanate whisker (average length = 1)
(C) synthetic resin emulsion or water-soluble synthetic resin (c) -1: acrylic emulsion (non-volatile content = about 50
%) (C) -2: Water-soluble acrylic resin (non-volatile content = about 40%) (d) Water or hydrophilic organic solvent (d) -1: Ion-exchanged water (d) -2: Ethylene glycol (e) Other Component (e) -1: Silicon-based leveling agent

[0032]

[Table 1]

Using the compositions A to C, a coating film was formed on a hot-dip galvanized test piece, and a wetting test and a real environment exposure test were performed. The test piece is a commercially available hot-dip galvanized steel sheet with a size of 70 × 150 mm,
The thickness is 3.2 mm. After cleaning the surface of the test piece, the above composition was sprayed with an air spray gun to form a coating film having a thickness of about 50 μm and dried at room temperature.

In the comparative example, a polyester film was formed on the same test piece, and a film having a thickness of about 60 μm was formed by an electrostatic powder coating method using a commercially available powdered polyester paint.

In the wetting test, a wetting index was measured based on JIS K-6768. In the actual environment exposure test, the vehicle was exposed to an automobile at a location adjacent to a highway where dust was intense for about one year with a vertical mounting angle, and the visual evaluation of dirt and the evaluation of blistering and peeling were performed. Table 2 collectively shows the test results of Examples and Comparative Examples using the compositions A to C.

[0036]

[Table 2]

As can be seen from the table, the coating films using any of the compositions A to C have a wetting index of 72 or more, indicating that they exhibit extremely high hydrophilicity. In the evaluation of the stain after one year of exposure, it was confirmed that the stain due to dust adhesion was remarkably improved as compared with the polyester film of the comparative example.

Further, the test pieces of the examples were tested for adhesion (based on JIS K-5400-8.5.1 cross cut test), hardness (based on JIS K-5400-8.4.2 pencil scratch test), and withstand resistance. Impact (JISK-5400-
8.3.1), weather resistance (JISK-5400-)
Using a sunshine carbon arc type weather meter in accordance with 9.8.1, the coating film after 3000 hours of exposure was visually observed), and the like. As a result, these properties were equal to or higher than those of the conventional polyester coating film. It was confirmed that it showed the performance of.

[0039]

The durable hot-dip galvanized steel material of the present invention comprises:
The surface is coated with high hydrophilicity, air permeability, high adhesion, weather resistance, hardness, etc., so it has excellent rust prevention and durability. Excellent in nature. Therefore, the durable hot-dip galvanized steel material of the present invention is particularly effective in preventing deterioration of the scenery and visibility due to the adhesion of dirt to the surface of a road steel material or the like in a polluted environment.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B05D 7/24 303 B05D 7/24 303B B32B 15/08 B32B 15/08 Q C23C 22/53 C23C 22/53 26/00 26/00 C (72) Inventor Toyo Ando 2-11-9, Iwamotocho, Chiyoda-ku, Tokyo Japan Inside Steel Corrosion Protection Co., Ltd. (72) Inventor Shoichi Kawasaki 2-11, Iwamotocho, Chiyoda-ku, Tokyo No. 9 Date F Corrosion Protection Co., Ltd. F-term (Reference) 4D075 BB26Z CA13 CA32 CA37 DB05 DC05 EA23 EB02 EC02 4F100 AA03B AA08B AA12B AA15B AA17B AA20 AA21 AA23 AA24 AB00B AB03A AB18A AH02 E02BA02B02B JD02B JK12 JL06 JL09 JL09B YY00B 4K026 AA02 AA07 AA13 AA22 BA01 BA02 BB02 BB03 BB06 BB08 BB10 CA27 CA39 CA41 DA02 EB11 4K044 AA02 AB02 BA10 BA11 BA1 2 BA14 BA21 BB03 BC01 BC02 BC04 BC05 BC06 CA11 CA16 CA53 CA62

Claims (4)

[Claims] 1. A durable hot-dip galvanized steel material, wherein the hot-dip galvanized steel material is coated with a coating film having hydrophilicity, air permeability, and high weather resistance. 2. The coating film comprises: (a) 5 to 15 parts by weight of a quaternary ammonium silicate in terms of SiO ₂ ; (b) 15 to 75 parts by weight of an inorganic filler; and (c) a synthetic resin emulsion. And / or 2 to 1 water-soluble synthetic resin in terms of synthetic resin.
A composition containing 2 parts by weight and the remainder consisting of (d) water or / and a hydrophilic organic solvent (provided that (a) + (b) + (c) + (d) = 100 parts by weight) is applied. The durable hot-dip galvanized steel material according to claim 1, wherein: 3. The group in which the inorganic filler in the composition comprises a water-insoluble fine particle or short fiber metal oxide, metal hydroxide, metal carbide, metal nitride, metal carbonate, and metal. 3. A durable hot-dip galvanized steel material according to claim 2, which is at least one member selected from the group consisting of: 4. The method according to claim 2, wherein a surface of the hot-dip galvanized steel material is provided.
4. A method for coating a durable hot-dip galvanized steel material, comprising applying 25 to 250 g of the composition according to claim 3 per square meter in terms of solid content and curing at room temperature or at low temperature.