Coating processes – With post-treatment of coating or coating material – Heating or drying
Reexamination Certificate
1999-06-10
2001-01-30
Cameron, Erma (Department: 1762)
Coating processes
With post-treatment of coating or coating material
Heating or drying
C524S001000, C524S284000
Reexamination Certificate
active
06180177
ABSTRACT:
TECHNICAL FIELD
The present invention relates to the composition of a surface-treatment agent and the treating method, which can impart to the surface of metallic materials a high corrosion-resistance and can form a film having improved fingerprint resistance, blackening resistance and adhesiveness of the paint coating.
BACKGROUND TECHNIQUE
Such metallic materials as steel sheets plated with a zinc-containing metal, aluminum sheets and the like are used in broad fields such as automobiles, building materials and appliances. However, the zinc and aluminum used in these metallic materials are corroded in ambient air to form a corrosion product which is the so-called white rust. This corrosion product disadvantageously impairs the appearance of metallic materials and further detrimentally effects the adhesiveness of the paint coating.
Therefore, in order to improve corrosion-resistance and adhesiveness of paint coating, chromating is usually applied on the surface of metallic materials by using a treating agent which contains as the main components chromic acid, bichromic acid or its salts.
Nevertheless, chromating is liable to often avoided because consciousness of environmental conservation is recently intensified. The hexavalent chromium contained in the chromating liquid used for treating the surface of metallic materials exerts detrimental influence directly upon the human body. In addition, the waste water, which contains hexavalent chromium, must be subjected to special treatment as stipulated under the Law of Prevention of Water Pollution. This is a reason that the total cost of the surface-treated metallic materials is considerably increased. In addition, when the equipment, in which the chromated metallic material is used, is discarded, the metallic material becomes industrial waste which, however, contains chromium. Although these materials are chromium-source, a serious disadvantage is that they cannot be recycled. This involves a socially serious problem.
Meanwhile, a well-known surface treating method other than chromating is that using a surface-treating agent which contains tannic acid which, in turn, contains polyphenol carboxylic acid. When the metallic material is treated with an aqueous solution of tannic acid, a protective film is formed by the reaction between the tannic acid and the metallic material. It is believed that since the protective film acts as a barrier against intrusion of corrosive material, the corrosion-resistance is enhanced.
However, since, recently, high corrosion-resistance of the film per se is required along with quality enhancement of the products, the corrosion-resistance attained by the tannic acid alone or the tannic acid together with an inorganic component falls short. It is not possible for such film, therefore, to be put to practical use under the present situation.
There is a disclosure in Japanese Unexamined Patent Publication (kokai) No. Sho 53-121034 to enhance the corrosion resistance, that is, an aqueous solution, which contains water dispersive silica, alkyd resin and trialkoxy silane compound, is applied on the metal surface and dried to form the coating film.
There are disclosure in Japanese Unexamined Patent Publications (kokai) Nos. Sho 57-44,751 and Hei 1-177,380 of a surface treatment method, in which a water-soluble resin consisting of a hydroxypyrone-compound derivative is used to impart to the metallic material the corrosion-resistance, and a method, in which a water-soluble or water-dispersive polymer of a hydroxystyrene compound is used to impart to the metallic material the corrosion resistance.
However, none of the above-described methods can form a film which has sufficiently high corrosion-resistance capable of substituting for the chromate film. The practical issue is, therefore, that the above-described problems have remain unsolved. Accordingly, it is strongly required under the present situation that the non-chromate surface-treatment agent and the treatment method be developed for the metallic material to improve corrosion-resistance.
It is an object of the present invention to solve the above described problems involved in the prior art, and to provide a non-chromate type surface-treatment agent for metallic materials, which agent can form on the surface of metallic material a film having improved corrosion-resistance, and which agent can improve fingerprint resistance, blackening resistance and adhesiveness of the paint coating. It is also an object of the present invention to provide a surface-treating method using the non-chromate type surface-treatment agent.
DISCLOSURE OF INVENTION
The present inventors repeatedly undertook intensive study to solve the problems involved in the prior art and discovered that a film, which exhibits improved corrosion-resistance, fingerprint resistance, blackening resistance and adhesiveness of the paint coating can be formed by means of treating the surface of metallic material with an acidic treating agent which contains a specific cationic component, a silane coupling agent and a water-soluble polymer having a specific chemical structure. The present invention was thus completed.
Namely, the composition of surface-treatment agent used for the metallic material is characterized by containing an aqueous medium and the following components dissolved in the aqueous medium.
(A) A cationic component, which consists of divalent or higher valent metallic ions selected from the group consisting of manganese, cobalt, zinc, magnesium, nickel, iron, titanium, aluminum and zirconium.
(B) At least one acid component selected from the group consisting of (1) fluoro-acid which contains four or more fluorine atoms, and one or more elements selected from the group consisting of titanium, zirconium, silicon, hafnium, aluminum and boron, (2) phosphoric acid, and (3) acetic acid.
(C) A silane coupling agent component which consists of at least one compound which contains at least one reactive functional group selected from an amino group containing active hydrogen, an epoxy group, a vinyl group, a mercapto group and methacryloxy group.
(D) At least one water-soluble polymer component, the polymerization unit of which is expressed by the following general formula (I) and has from 2 to 50 of the average polymerization degree n.
In the formula (I), X
1
bonded to the benzene ring expresses a hydrogen atom, a hydroxyl group, an alkyl group of C
1
to C
5
, a hydroxylalkyl group of C
1
to C
10
, an aryl group of C
6
to C
12
, a benzyl group, a benzal group, an unsaturated hydrocarbon group (formula II) which condenses with said benzene ring to form a naphthalane ring, or formula (III) mentioned below,
In the formula (II) X
2
bonded to the benzene ring expresses a hydrogen atom, a hydroxyl group, an alkyl group of C
1
to C
5
, a hydroxyalkyl group of C
1
to C
10
, an aryl group of C
6
to C
12
, a benzyl group and a benzal group, R
1
and R
2
in the formula (III) express, each or independently from one another, a hydrogen atom, a hydroxyl group, an alkyl group of C
1
to C
5
or a hydroxyalkyl group of C
1
to C
10
, and Y
1
and Y
2
in the formula (I), (II) and (III) bonded to the benzene ring express each or independently from one another a Z group expressed by the following formula (IV) and (V):
in said formula (IV) and (V), R
3
, R
4
, R
5
, R
6
and R
7
express, each or independently from one another, a hydrogen atom, an alkyl group of C
1
to C
5
or a hydroxyalkyl group of C
1
to C
10
, each of X
1
, and Y
2
coupled to a benzene ring of said polymerization units may be the same as or different from the X
1
, Y
1
and Y
2
coupled to the other benzene rings, and the average substitution value of said Z group in each benzene ring of said polymer molecules is from 0.2 to 1.0 in average.
Preferably, the composition of surface-treatment agent according to the present invention contains from 0.01 to 10% by weight of the cationic component based on the solid matter thereof.
Preferably, the composition of the surface-treatment agent according to the present invention contains f
Hayashi Hiroki
Nagashima Yasuhiko
Armstrong, Westerman Hattori, McLeland & Naughton
Cameron Erma
Nihon Parkerizing Co. Ltd.
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