JPH02218767A - Coating with antifouling function - Google Patents

Abstract

PURPOSE:To provide the title coating capable of effectively preventing stain due to metallic ions produced by corrosion of iron-and-steel structures, etc., and of retaining external rust staining-preventive effect for a long period, containing a specified proportion of a pigment from an acid having both carboxyl and hydroxyl groups or its derivative. CONSTITUTION:The objective inexpensive coating applicable not only to metal surfaces but also as a topcoating or undercoating over a wide range, comprising (A) 3-75wt.% of a pigment from an acid having both carboxyl and hydroxyl groups (e.g. hydroxycarboxylic acid) or its derivative (e.g. citric acid or its derivative) and (B) an extender pigment, rust-resisting pigment, color pigment and other coating composition(s).

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a paint having the function of preventing staining due to adhesion of metal ions or metal oxides on the painted surface of structures and the like. More specifically, the present invention relates to a paint that prevents staining caused by adhesion of metal ions or metal oxides to the surface, which are generated due to corrosion of steel structures and the like.

[Prior art 1] Conventionally, paints that react with metal ions and prevent stains due to the adhesion of metal oxides on the surface of the coating composition have been disclosed in Japanese Patent Application Laid-open No. 58-219273 and Japanese Patent Application Laid-Open No. 61-1999 as paints for preventing external rust contamination.
-218666, but the problems in this patent are mainly related to etidronate, which is a derivative of organic polyphosphonic acid (British Patent Application No. 2121419), and glasses that release phosphate ions (British Patent Application No. 2073730, British Patent Application No. 160).
4383, European Patent No. 35798), etc., and in its application, JP-A-61-218666 can only be applied as a top coat for surfaces other than bare metal surfaces, which limits its scope of application. was. This is because when etidronate, which is a derivative of the organic polyphosphonic acid mentioned in the patent, comes into contact with a bare metal surface, the metal is eluted because the pigment is an acid, which significantly reduces the adhesion of the paint film. This is because it causes swelling and peeling.

An important problem to be raised is that the effect of preventing external rust contamination does not last long, as is clear from the comparative examples of the present invention.

[Problems to be Solved by the Invention] The present invention aims to prevent stains caused by adhesion of metal ions or metal oxides on painted surfaces by reacting with metal ions generated when steel structures etc. are corroded. It is aimed at overcoming the shortcomings of the prior art: the use of special pigments, the limitations of the scope of application, and the use of cheap and common substances as additives, not only on metal surfaces, but also on everything to which paint can normally be applied. It was developed for the purpose of being applied as a top coat, undercoat, etc.

[Means for Solving the Problems 1] The present invention is a paint consisting of a pigment and a binder that has the function of preventing stains due to the adhesion of metal ions or metal oxides on the painted surface, The present invention provides the above-mentioned coating material, characterized in that it contains 3 to 75% by weight of a pigment of an acid or a derivative thereof.

The feature of the present invention is that the pigment of an acid having a carboxyl group and a hydroxyl group (hydroxycarboxylic acid) or a derivative thereof is
By blending % by weight into the paint, it is possible to react with metal ions and prevent stains due to attachment of metal ions or metal oxides to the painted surface.

The coating composition of the present invention may contain extender pigments, rust-preventive pigments, coloring pigments, and other additives added to the coating composition in addition to the constituent pigments, which are acids having carboxyl groups and hydroxyl groups or derivatives thereof. It is possible to mix and use them simultaneously.

Furthermore, there are no limitations on the paint binder to be used. In other words, any paint binder can be used, regardless of whether it is water-based or solvent-based. The amount of acid pigments or their derivatives having carboxyl groups and hydroxyl groups in the paint is limited to 3 to 75% by weight.If the amount is less than 3% by weight, no stain prevention effect can be obtained, and if it exceeds 75% by weight, However, this is because it is hardly possible to improve the stain prevention effect.

[Function] The additive used in the present invention is an acid having a carboxyl group and a hydroxyl group (hydroxycarboxylic acid) or a derivative thereof, such as citric acid and its salts, tartaric acid and its salts, gluconic acid and its salts. etc. These acids react immediately with metal ions before they oxidize, and can prevent stains caused by metal oxides adhering to the surface.

The mechanism for preventing staining by these acids is currently unclear;
Although intensive investigation is currently underway, these effects are characteristically seen in acids with carboxyl and hydroxyl groups, which are used as complexing agents in the plating field to stably retain metal ions in the plating bath. It is used for.

This suggests that it complexes metal ions and prevents their oxidation. Furthermore, since the reaction product of the additive and iron ion used in the present invention does not gel, when the paint swells, it is not oxidized due to the complexing effect, and the reaction product can be discharged out of the system in minute amounts.

The metal ions referred to here are metal ions etc. that are generated when the steel base of steel structures etc. is corroded.
It reacts immediately with these and prevents stains caused by metal oxide adhesion on the paint surface.

Further, when the paint according to the present invention is applied directly to a metal surface, it complexes with the active metal surface and becomes inactive, contributing to improvement of paint film adhesion and corrosion resistance.

[Example] Next, the invention will be explained in detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

The test piece was 5S41 with mill scale removed by hydrochloric pickling.
A steel plate (size 7 x 15 x O, 14am) was coated with Trick 1100 primer manufactured by Nippon Bar Power Ising ■, and as a top coat, No. 1.2.3.
100p of the paints of Examples 1 to 17 (including Comparative Example 10) and Fourth Comparative Example 1.2 shown in Table 4 were applied. In addition, Examples 1 to 1 were applied to the same steel plate without applying primer.
7 (including Comparative Example 10) and Comparative Example 1.
1 coat was applied. Additionally, a mortar test piece (size 1)
0x25x2.5cm) and coated with 20011 coats of the paints of Examples 1-17 (including Comparative Example 10) and Comparative Example 1.2.

Table 1 Examination of antifouling effect by additive system Table 3 Examination of antifouling effect by additive blending amount Table 2 Examination of antifouling effect by resin system Table 4 Examination and comparison of joint use with antirust pigment A 1 mmΦ iron wire was wound once on the upper part of the test piece of Material Examples 1 to 17 (including Comparative Example 10) as a metal ion outflow source. The test surface of the specimen was exposed to the atmosphere at an angle of 45 degrees and subjected to a salt spray test, and the degree of contamination of the painted surface was observed.

The results of atmospheric exposure show that in Examples 1 to 17 of the present invention, excluding Comparative Example 10, the coating composition remained unchanged even in the second year when it was applied as a top coat composition on top of the brimer and when it was applied directly to the steel plate surface without the brimer. Almost no dirt was observed on the surface. In particular, products with a large amount of additives, such as Example 13, have excellent antifouling performance and sustainability of antifouling performance (3
(Based on annual evaluation) Both were good. In Comparative Example 1, yellow and black stains adhered to the test surface after 5 months of exposure both when it was applied as a top coat over a primer and when it was applied directly to a steel plate surface without primer. Comparative Example 2, which was applied as a top coat on top of the primer, was exposed to 1
Yellow and black stains adhered to the test surface after 3 months.

In the salt spray test, Comparative Example 10 and Comparative Example 1 showed stains that appeared to be metal ions or their compounds on the test surface after 70 hours when applied as a top coat on top of the primer and when applied directly to the steel plate surface without primer. was attached. Comparative example 2 applied as a top coat over the brimer
Dirt adhered to the surface after 220 hours. In Examples 1 to 17 of the present invention, excluding Comparative Example 10, staining was observed after 480 hours in both cases when the composition was applied as a top coat composition on top of the primer and when it was applied directly to the steel plate surface without primer application.

Through these tests, additive-based (Table 1), resin-based (
(Table 2), the amount of additives used in the present invention (Table 3), the use in combination with other anti-rust pigments (Table 4), and when applied to materials other than metal as an undercoat or topcoat. The effects of the present invention were also clearly recognized.

[Effects of the Invention] The present invention provides a paint that effectively prevents stains caused by metal ions or metal oxides generated by corrosion of steel structures or the like from adhering to the surface. Note that stains can be effectively prevented even when applied as an undercoat or topcoat in combination with other rust-preventing pigments to surfaces other than metals.

Claims (1)

[Claims] A paint consisting of a pigment and a binder that has the function of preventing staining due to the adhesion of metal ions or metal oxides on the painted surface, containing 3 to 75% by weight of acid or derivative pigments having carboxyl groups and hydroxyl groups. The paint characterized by comprising: