JPS5823422B2 - White colored coating composition for galvanized iron plates - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a white colored coating composition for galvanized iron plates.

Clear or enamel made by adding amino resin such as melamine resin, guanamine resin, or urea resin to acrylic resin, alkyd resin, or oil-free polyester resin.
Alternatively, colored zinc is produced by applying a coating composition modified by adding a mixture of tetra- to hexamers of ethyl silicate to clear or enamel modified by adding vinyl resin, epoxy resin, etc., and baking and drying the coating composition. The method for painting iron plates was awarded Japanese Patent No. 852207-1 (Special Publication No.
-27249.

However, although the colored galvanized iron plate (pre-coated metal) obtained by this coating method has excellent corrosion resistance on flat surfaces and cross-cut areas, the coating on processed areas such as bent areas and impact areas is poor. The corrosion resistance of the paint film in processed areas was poor (rusting, blistering, etc.) due to cracking and the synergistic effect of the compression applied to the paint film and the strain caused by tensile stress.

One way to prevent such rust and blisters is to use romate-based rust preventive pigments such as zinc chromate and strontium chromate, but these pigments make the paint film yellow, so white or pale colored It was either not possible to use this type of paint, or even if it could be used, there was a limit to how much it could be used.

In view of the current situation, the present inventors have conducted various studies and found that borate compounds not only have antirust properties, but also exhibit a white to grayish white color both in the form of powder and in the form of enamel. It was discovered that the corrosion resistance of the processed part could be improved by not coloring the coating film in any way and by using it in combination with a mixture of tetra- to hexamers of ethyl silicate, and the present invention was completed based on this discovery. It is.

That is, the present invention provides an enamel made by adding an amine resin, a borate compound, and optionally a modifying resin to an acrylic resin, an alkyd resin, or an oil-free polyester resin, and adding a mixture of ethyl silicate tetra-hexamers to the enamel. This invention relates to a white colored coating composition for galvanized iron plates.

As the acrylic resin used in the present invention, functional group-containing monomers and other polymerizable polymers constituting ordinary thermosetting acrylic resins for paints are used, and conventionally known polymerization methods, preferably solution polymerization methods, are used. can be easily obtained using a polymerization initiator.

Here, examples of the functional group-containing monomer include acrylic acid, methacrylic acid, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, etc. Examples of the monomer include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate,
Isopropyl acrylate, isopropyl acrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, lauryl acrylate, lauryl methacrylate, acrylamide, methacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, styrene, a-methylstyrene, vinyltoluene,
Acrylonitrile, methacrylate trile, etc. may be mentioned, and examples of polymerization initiators include peroxide type (e.g. benzoyl peroxide, t-butylperoxybenzoate, etc.), azo type (e.g. azobisisobutyronitrile etc.), etc. It will be done.

The alkyd resin used in the present invention can be easily obtained by a conventionally known esterification reaction using polyhydric alcohols, polybasic acids, fats and oils, etc. that constitute ordinary alkyd resins for paints.

Here, examples of polyhydric alcohols include ethylene glycol, propylene glycol, diethylene glycol, neopentyl glycol, chrycerin, trimethylolpropane, and pentaerythritol, and examples of polybasic acids include phthalic acid and phthalic anhydride. acids, isophthalic acid, maleic acid, maleic anhydride, fumaric acid,
Examples of oils and fats include soybean oil, linseed oil, safflower oil, coconut oil, dehydrated castor oil, and tall oil; fatty acids obtained from them; Examples include aliphatic monocarboxylic acids (eg, capric acid, lauric acid, palmitic acid, stearic acid, oleic acid, etc.).

The oil-free polyester resin used in the present invention can be easily obtained by a conventionally known esterification reaction using polyhydric alcohols and polybasic acids that constitute oil-free polyester resins for paints.

Here, examples of the polyhydric alcohol and polybasic acid include those mentioned above as the polyhydric alcohol and polybasic acid constituting the alkyd resin.

Examples of borate compounds used in the present invention include zinc borate (2ZnO.3, B2O3.3.5H20), calcium borate (CaO.B2O3.5H20), and potassium tetraborate (K2O.2B203.5H20). Examples include calcium tetraborate (Ca0.2B203.6H20), sodium tetraborate (Na20.2 B 20 a ), zinc tetraborate (ZnO.2B203), and zinc borate is particularly preferred.

These borate compounds may be used alone or as a mixture of two or more.

Examples of amine resins include melamine resins, urea resins, and guanamine resins, which are used as curing resins.

Furthermore, examples of the modifying resin that may be added as necessary include vinyl resin, epoxy resin, blocked incyanate, and the like.

In addition, 4 of the ethyl silicate used in the present invention
The hexamer mixture is an oily liquid, but it is colorless and transparent, so it can be mixed with not only white pigments but also aluminum pigments and other various pigments to make paints of all colors, and it can also be used as a paint film. Because a network structure is formed during the formation process, the resulting coating film is tight and exhibits good corrosion resistance.

The white colored coating composition for galvanized iron plates of the present invention contains a borate compound based on 100 parts by weight of a total resin consisting of an acrylic resin, an alkyd resin, or an oil-free polyester resin, an amine resin, and, if necessary, a modifying resin. 1-50
Parts by weight, preferably 4 to 30 parts by weight, are kneaded together with various pigments to form enamel.

Next, 2 to 50 parts by weight of a mixture of ethyl silicate tetramers to hexamers are added to 100 parts by weight of this enamel and mixed well.

Here, if the amount of the borate compound is less than 1 part by weight based on 100 parts by weight of the total amount of resin, the antirust ability will not be exhibited, and if it exceeds 50 parts by weight, the weather resistance of the coating film will be reduced.

In addition, if the mixture of tetra-hexamers of ethyl silicate is less than 2 parts by weight per 100 parts by weight of enamel, the anti-rust effect will not be exhibited, and if it exceeds 50 parts by weight, the viscosity of the paint will be low. In addition to worsening color stability and storage stability, the gloss of the paint film also deteriorates.

The white colored paint composition for galvanized iron plates of the present invention uses a mixture of ethyl silicate tetra- to hexamers and a borate compound, so due to the synergistic effect, the resulting paint film has excellent corrosion resistance. Not only can it be used as a white paint, such as white or light-colored paint, but it can also be used as a paint with various tones using aluminum pigments and other various pigments. Apply as one coat or two coats on an electrodeposition primer using various methods such as roller coating, flow coating, and spraying, and obtain a good coating film by heating and drying at 180 to 350°C for 15 to 120 seconds. I can do it.

The resulting coating film exhibits 2 to 3 times the corrosion resistance compared to coatings made with paints that do not contain borate compounds, and is effective against corrosion not only on flat areas and cross-cut areas, but also on bent areas and impact areas. Excellent corrosion resistance of processed parts.

Next, Examples and Comparative Examples will be shown, and parts in the examples are parts by weight.

Example 1 Acrylic resin 7 consisting of acrylic acid, 2-hydroxyethyl methacrylate, methyl methacrylate, butyl acrylate-12-ethylhexyl acrylate, and styrene
0 parts, melamine resin (Melan 23 manufactured by Hitachi Chemical) 20
Part, epoxy resin (Epicor manufactured by Shell Chemical Company) 1
(60 parts of 001 dissolved in 20 parts of methyl isobutyl ketone and 20 parts of butanol) 10 parts, zinc borate 1
Enamel was obtained by dispersing 0 parts of titanium white and 70 parts of titanium white overnight with an attritor.

4 to 4 parts of ethyl silicate per 100 parts of this enamel.
20 parts of a hexamer mixture was added and mixed well to obtain a white colored coating composition for galvanized iron plates.

This white colored paint composition for galvanized iron plates was applied with a roll coater to a galvanized steel plate that had been treated with zinc phosphate, coated with an electrodeposition primer to a dry film thickness of 5 μm, and flashed off. Paint it so that it becomes 260
A coating film was obtained by heating and drying at ℃ for 40 seconds.

As shown in Table 1, this coating film has excellent corrosion resistance in the processed parts, and is found to be suitable for pre-coated metal.

Example 2 70 parts of an oil-free polyester resin consisting of phthalic anhydride, adipic acid, ethylene glycol, and trimethylolpropane, 30 parts of melamine resin (mentioned above), 10 parts of zinc borate, and 70 parts of titanium white were dispersed overnight with an attritor. and got the enamel.

4 to 4 parts of ethyl silicate per 100 parts of this enamel.
40 parts of a hexamer mixture was added and mixed well to obtain a white colored coating composition for galvanized iron plates.

This white colored coating composition for galvanized iron plates was applied to a galvanized steel plate treated in the same manner as in Example 1 using a roll coater.
The coating was applied to a dry film thickness of 15 μm at 220°C.
A coating film was obtained by heating and drying for 0 seconds.

As shown in Table 1, this coating film has excellent corrosion resistance in the processed parts, and is found to be suitable for pre-coated metal.

Example 3 70 parts of alkyd resin containing 25% soybean oil fatty acid, phthalic anhydride, adipic acid, glycerin, trimethylolpropane, 30 parts of melamine resin (example 1), 10 parts of zinc borate, titanium Enamel was obtained by dispersing 70 parts of white with an attritor overnight.

4 to 4 parts of ethyl silicate per 100 parts of this enamel.
40 parts of a hexamer mixture was added and mixed well to obtain a white colored coating composition for galvanized iron plates.

This white colored coating composition for galvanized iron plates was applied to a galvanized steel plate treated in the same manner as in Example 1 using a roll coater.
The film was coated to a dry film thickness of 15 μm at 220°C.
A coating film was obtained by heating and drying for seconds.

As shown in Table 1, this coating film has excellent corrosion resistance in the processed parts, and is found to be suitable for pre-coated metal.

Comparative Example 1 A coating composition was obtained in the same manner as in Example 1, except that zinc borate in the formulation of Example 1 was replaced with titanium white.

This coating composition was applied to a galvanized steel plate treated in the same manner as in Example 1 using a roll coater so that the dry film thickness was 15μ, and the coating was dried by heating at 260°C for 40 seconds to obtain a coating film. Ta.

As shown in Table 1, this coating film is found to have inferior corrosion resistance in the processed areas compared to Example 1.

Comparative Example 2 A coating composition was obtained in the same manner as in Example 2, except that zinc borate in the formulation of Example 2 was replaced with titanium white.

This coating composition was applied to a galvanized steel plate treated in the same manner as in Example 1 using a roll coater so that the dry film thickness was 15 μm, and the coating was dried by heating at 220° C. for 60 seconds to obtain a coating film. .

As shown in Table 1, this coating film is found to have inferior corrosion resistance in the processed areas compared to Example 1.

Comparative Example 3 A coating composition was obtained in the same manner as in Example 3, except that zinc borate in the formulation of Example 3 was replaced with titanium white.

This coating composition was applied to a galvanized steel plate treated in the same manner as in Example 1 using a roll coater so that the dry film thickness was 15μ, and the coating was dried by heating at 220°C for 60 seconds to obtain a coating film. ≠5 As shown in Table 1, it can be seen that this coating film has inferior corrosion resistance in the processed parts compared to Example 3.

(B) ◎: No abnormalities ○: Some rust and blisters occur, △: Rust and blisters occur over % to % of the painted surface, ×
: Rust and blisters occur over almost the entire painted surface.

Claims (1)

[Scope of Claims] 1. Enamel made by adding an amino resin, a borate compound, and, if necessary, a modifying resin to an acrylic resin, an alkyd resin, or an oil-free polyester resin. A white colored coating composition for galvanized iron plates, which is obtained by adding a mixture of ethyl silicate tetramer to hexamer to ethyl silicate.