JP2003328151A - Method of producing corrosion resistant iron material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of producing a highly corrosion resistant iron material which has high rust preventability without using and containing harmful chromium based compounds. <P>SOLUTION: A rust preventive coating composition containing (a) a compound having a phenolic hydroxy group and (b) at least one or more kinds of compounds selected from the group of silicates and the salts of silicic acid and having a siloxane bond and/or their condensations as essential components is applied to the surface of an iron material whose surface is coated with an undercoating agent essentially consisting of at least one kind of metal selected from zinc and aluminum, and hardening is caused by room temperature treatment or heating treatment, so that a corrosion resistant iron material is produced. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a corrosion resistant iron material. More specifically, the present invention relates to a method for producing a highly corrosion-resistant iron material useful as an iron material requiring high corrosion resistance in construction materials, construction machinery, ships, boats, bridges, automobiles, vehicles and the like.

[0002]

2. Description of the Related Art Conventionally, anticorrosion treatment of iron has been widely performed, and these methods include blocking oxygen and water by various paints; metals such as nickel, copper, chromium, cadmium, zinc, aluminum and tin. , Enamel; inorganic coating represented by chemical conversion treatment with chromate and phosphate; and cathodic protection. Above all,
As a high-corrosion resistance processing method when particularly high rust prevention performance is required, the iron material surface is first coated with zinc or aluminum-based metal to form an undercoat layer, and then a chromic acid-based chemical conversion treatment (chromate treatment) is applied as an overcoat. Then, a method of providing a protective layer of a paint if necessary has been put into practical use. This treatment with chromium is extremely effective for rust prevention, but hexavalent chromium contained in the material used for chromate treatment is harmful to the human body and causes liver failure, skin ulcers, rhinitis, asthma, etc. Therefore, it has become a social problem in recent years.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for producing a corrosion-resistant iron material having high rust preventive properties without using and containing a harmful chromium compound.

[0004]

The above object of the present invention is to:
By an undercoating agent containing at least one metal selected from zinc and aluminum as a main component, a rust preventive coating composition containing the following (a) and (b) as essential components is applied to the surface of the iron material having the surface coated, This is achieved by forming a cured film by room temperature treatment or heat treatment. (A) at least one selected from the group consisting of compounds having at least one phenolic hydroxyl group in the molecule, (b) silicates represented by the general formula (1), and silicates represented by the general formula (2) Compounds having one or more kinds of siloxane bonds and / or condensates thereof

[0005]

[Chemical 3]

(In the formula, R is a hydrogen atom or a group selected from the group of monovalent hydrocarbon groups, provided that when R is plural, they may be the same or different, and m is an integer of 1 or more. is there)

[0007]

[Chemical 4]

(In the formula, M is a group selected from the group of alkali metals and ammoniums, provided that when M is plural, they may be the same or different, and n represents an integer of 1 or more.)

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The undercoat layer formed on the surface of an iron material in the present invention is a film made of a metal containing as a main component at least one metal selected from zinc and aluminum having a larger ionization tendency than iron, This coating metal serves as a sacrificial anode and can prevent oxidation of the iron material. The undercoat layer of these metals can be formed by any known method such as melt plating, electroplating, permeation plating, chemical plating and thermal spraying, and coating with a coating containing fine powders of these metals.

Examples of the compound having at least one phenolic hydroxyl group in the molecule of component (a) in the anticorrosive coating composition used in the present invention include phenol, cresol, thymol, bromophenol, naphthol, anilinophenol and the like. Phenolcatechin (catechol), resorcin, hydroquinone, orcin, urushiol, bisphenol A, binaphthol, and other divalent phenols; pyrogallol, phloroglucin, hydroxyhydroquinone, trihydroxybenzoic acid, etc. Examples thereof include trihydric phenols; however, the present invention is not limited to these.

The compounds having at least one phenolic hydroxyl group in these molecules can be used alone or in admixture of two or more. These phenols react with iron to form an iron salt to form a complex compound and reduce oxygen permeability, so that oxidation of zinc or aluminum in the undercoat layer can be suppressed. as a result,
It is considered that since the deterioration of the performance of the above metal in the undercoat layer as the sacrificial anode is suppressed, the long-term high corrosion resistance of the iron material can be obtained.

The component (b) used in the present invention is such that the silanol groups are dehydrated and condensed by drying to form a strong protective coating film by three-dimensional crosslinking, and at the same time, the component (a) is supported.

The silicates represented by the formula (1) of the component (b) are usually oligomers obtained by dehydration condensation of silicon alkoxide. The structure and molecular weight of the alkoxide are not particularly limited, but methyl silicate obtained by the dehydration condensation of tetramethoxysilane and ethyl silicate obtained by the dehydration condensation of tetraethoxysilane are easily available and highly reactive, and the use of the present invention Suitable for

Examples of the silicate represented by the formula (2) of the component (b) include alkali metal salts such as lithium silicate, sodium silicate and potassium silicate, methyltripropanolammonium silicate, dimethyldipropanolammonium. Examples thereof include amine silicates such as silicates, but are not limited to these.

The compounds having a siloxane bond represented by the formulas (1) and (2) can be used alone or in admixture of two or more kinds. Further, the compounds having a siloxane bond represented by the formula (1) and the formula (2) may be used alone or in combination of two or more, and further subjected to a condensation reaction to be used as a high molecular weight product and / or a cocondensate. You can also

The mixing ratio of the component (a) and the component (b) may be determined according to the required rust preventive performance and is not particularly limited. However, the coatability of the composition of the present invention,
From the viewpoint of cured film strength, it is preferable to use component (a) and component
(B) Weight mixing ratio (a): (b) is 5:95 to 40:60,
More preferably, it is 10:90 to 20:80.

The rust-preventive coating composition may be applied by spraying, dipping, brushing, printing or the like to the surface of an iron material coated with an undercoating agent containing at least one metal selected from zinc and aluminum as a main component. You can The coating amount is usually 5 to 200 μm as a dry film thickness, but is not limited to this. In addition, the above-mentioned anticorrosive coating composition can be dried, for example, at room temperature for 2 to 10 hours after being applied, or can be heated to obtain a cured coating film in a shorter time. The heating conditions are heating at 100 to 300 ° C. for 10 minutes to 2 hours, and for example, a preferable cured coating film can be obtained by heating at 150 ° C. for 30 minutes to 1 hour. A compound having at least one phenolic hydroxyl group in the molecule of component (a) is fixed to the obtained coating film, and a coating film having excellent corrosion resistance is formed.

The rust-preventive coating composition of the present invention may contain other additives in appropriate amounts within a range that does not impair the characteristics of the composition of the present invention. Other additives include curing catalysts such as metal alkoxides added for the purpose of accelerating curing; diluting solvents such as alcohols, ketones and glycols added for the purpose of adjusting viscosity; glass, quartz, Inorganic fillers such as aluminum hydroxide, alumina, kaolin, talc, calcium carbonate, calcium silicate, magnesium hydroxide; organic fillers such as acrylic resin powder, epoxy resin powder, polyester resin powder; carbon black, red iron oxide, phthalocyanine blue, Examples include colorants typified by pigments and dyes such as chrome yellow and titanium dioxide; metal powders; lubricants; release agents; surfactants; coupling agents and the like.
It is not limited to these. Furthermore, the corrosion-resistant iron material produced by the present invention can be coated with various paints / coating agents for the purpose of protecting, decorating, and coloring the surface.

[0019]

EXAMPLES Hereinafter, typical examples of the present invention will be described in more detail with reference to examples. The present invention is not limited to the following examples. In the examples, simply "part" means "part by weight". (Preparation of Topcoat Composition) The compositions shown in Table 1 (Examples 1 to 1)
6, Comparative Examples 1 to 3) were prepared. A predetermined amount of each raw material shown in Table 1 was placed in an Erlenmeyer flask, and the mixture was stirred and mixed at room temperature for 30 minutes, and then filtered through a nylon mesh having an opening of 50 μm to prepare a topcoat composition. Raw materials (A) in the table
(F) is a component as shown below. (A) Methyl silicate (MS-51 Mitsubishi Chemical Corporation) (B) Ammonium silicate (Amine silicate Q
AS-25 Nissan Chemical Industries Ltd.) (C) Pyrocatechin (Kanto Chemical Co., Inc.) (D) 3,4,5-Trihydroxybenzoic acid ethyl ester (Kanto Chemical Co., Ltd.) (E) Methyltrimethoxysilane (Japanese) (Kou Pure Chemical Industries, Ltd.) (F) Tetrabutoxyzirconate (Organics Z
A-60 Matsumoto Pharmaceutical Co., Ltd.) (G) 99.5% ethanol (Kanto Chemical Co., Inc.)

[0020]

[Table 1]

(Preparation of Specimen) After the surface of a steel plate of 25 × 100 × 2 mm was washed by the shot blast method, zinc was applied by the thermal spraying method so that the amount of adhesion was 20 g / m ² .
The zinc-treated steel plate was dipped in the composition shown in Table 1 for 10 minutes, then withdrawn, dried at room temperature for 30 minutes, and further dried for 150 minutes.
A test piece was dried in an oven at ℃ for 1 hour. (Salt spray test) 5% saline was continuously sprayed on one surface of the prepared test piece, and the period until the occurrence of red rust on the surface of the steel plate was visually observed. In each test, three test pieces were used, and the time from the start of spraying the saline solution to the time when rust was observed on the surface of the two test pieces was observed. The results are shown in Table 2.

[0022]

[Table 2]

As is apparent from the results shown in Table 2, Examples 1 to 3 prepared using the anticorrosive coating composition of the present invention
It was proved that the rust generation time of the 6 test pieces was remarkably longer than that of the test pieces of Comparative Examples 1 to 3.

[0024]

The corrosion-resistant iron material produced according to the present invention is
Shows high corrosion resistance without containing harmful chromium compounds. Therefore, the iron material manufactured by the present invention is suitable for members such as building materials, construction machinery, ships, boats, bridges, automobiles, and vehicles.

Claims (2)

[Claims] 1. A rust-preventive coating composition comprising the following components (a) and (b) as essential components on a surface of an iron material whose surface is coated with an undercoating agent whose main component is at least one metal selected from zinc and aluminum. A method for producing a corrosion-resistant iron material, which comprises applying an object and curing it by room temperature treatment or heat treatment. (A) at least one selected from the group consisting of compounds having at least one phenolic hydroxyl group in the molecule, (b) silicates represented by the general formula (1), and silicates represented by the general formula (2) Compounds having one or more siloxane bonds and / or their condensates (In the formula, R is a hydrogen atom and a group selected from the group of monovalent hydrocarbon groups, provided that when R is plural, they may be the same or different, and m is an integer of 1 or more. Yes) [Chemical 2] (In the formula, M is a group selected from the group of alkali metals and ammoniums, provided that when M is plural, they may be the same or different, and n is an integer of 1 or more.) 2. The rust preventive coating composition comprises: (a) a compound having at least one phenolic hydroxyl group in the molecule and (b) a compound having a siloxane skeleton represented by the general formula (1), or a condensate thereof. And (a): (b) is 5:95
The method for producing a corrosion-resistant iron material according to claim 1, which is a rust-preventive coating composition contained in a mixing ratio of -40: 60.