Metal treatment – Process of modifying or maintaining internal physical... – Processes of coating utilizing a reactive composition which...
Reexamination Certificate
2001-03-02
2002-09-10
Sheehan, John (Department: 1742)
Metal treatment
Process of modifying or maintaining internal physical...
Processes of coating utilizing a reactive composition which...
C148S264000, C148S267000, C252S389500, C106S014130
Reexamination Certificate
active
06447620
ABSTRACT:
FIELD OF THE INVENTION
The present invention pertains to a water-based surface-treating agent for metallic materials. In more detail, the present invention pertains to a water-based surface-treating agent for metallic materials for use in rustproofing metallic materials that require surface protection, such as iron, steel, zinc, aluminum, magnesium, stainless steel, tin, and titanium, and particularly plated steel materials prepared by plating the surface of steel materials, which are one of the most important industrial materials, with zinc, zinc-based alloys, aluminum-zinc alloys, aluminum, etc.
BACKGROUND TECHNIQUES
Metallic materials, particularly steel materials which are typical of these materials, still maintain a firm premier position among industrial materials owing to their excellent physical properties and economic advantages. Noteworthy and ceaseless effort is being made to control corrosive wear, which is the weakest feature of steel materials. Typical materials of this kind include plated steel materials prepared by plating the surface of steel materials with zinc, zinc-based alloys, aluminum-zinc alloys, aluminum, etc. Coating metals such as zinc, zinc-based alloys, aluminum-zinc alloys, and aluminum applied on the surface of steel materials usually become less noble in potential than the base steel materials and exhibit sacrificial protection. They also prevent wear of the coating layer itself by forming a barrier compound layer on the surface, thus enabling the protection of the base steel materials over long periods of time.
The zinc, zinc-based alloys, aluminum-zinc alloys, and aluminum coating layers, which are oxidized in actual use environments, form barrier compound layers that consist of oxides, hydroxides, carbonates, chlorides, etc., of these metals on the surface, and thereby protect the coating metal layers, but the barrier effect is not perfect; thus the coating layers gradually wear and the base materials begin to corrode at the points where the coating layers have disappeared. The barrier compound layers have white rust exhibiting a white color or black rust exhibiting a gray-to-black color and are not preferred from the standpoint of appearance; when such rust forms in the distribution process before the plated steel materials made ready for use, there will inevitably be complaints regarding appearance. To deal with this, plated steel materials of this kind are usually subjected to a chromate treatment comprised mainly of a chromate before being shipped.
Of these plated steel products, sheet and strip products are produced in the largest volumes. Plated steel strip is produced by plating a strip-like steel product on a continuous plating line. Sheet products are typically made by plating the steel when it is in strip form, then cutting it on a slitter line. The productivity of a continuous plating line is extremely high, e.g., the line speed is generally 100-200 meters/min. The chromate treatment for plated steel strip is usually performed in a continuous plating line, this step being accomplished between the plating step and a steel strip winding device.
Because a continuous plating line is operated at high speed, a reactive chromate treatment that requires a reaction time and a post-washing process is undesirable because the treatment zone would have to be long. Therefore, a non-reactive coating-type chromate treatment is generally employed. The treatment method involves bringing an aqueous composition that contains chromic acid into contact with the surface of plated steel sheet by spraying or dipping, then removing the excess liquid by roll wiping or gas wiping; or applying a fixed amount of said aqueous composition by a roll coater and then immediately drying by heated air, infrared rays, far infrared rays, or possibly by a method such as induction heating.
For some time after the first continuous plating line was constructed in Japan, treatment with a simple chromic anhydride aqueous solution was carried out as the chromate treatment. In the early days when plated steel sheet was first commercialized, only short-term rust prevention (white rust control) was required, but in recent years a wide variety of requirements, such as much higher corrosion resistance, blackening resistance, workability, fingerprint resistance, adhesion to topcoats, low pollution characteristics (proportion of fixed chromium), and chemical resistance of the coating, have developed and need to be satisfied.
Various surface treatment methods are known for providing higher added value by treatments using synthetic resin-containing chromate treatment solutions to satisfy the above-mentioned requirements. For example, a large number of related techniques are disclosed in Japanese Kokoku No. 44[1969]-5,285, Japanese Kokoku No. 44[1969]-8,337, Japanese Kokoku No. 49[1974]-31,026, Japanese Kokoku No. 49[1974]-40,865, Japanese Kokai No. 50[1975]-57,931, Japanese Kokoku No. 7[1995]-6,070, Japanese Kokoku No. 6[1994]-59,717, Japanese Kokai No. 5[1993]-279,867, and Japanese Kokai No. 6[1994]-192,850. These prior art techniques use water-soluble synthetic resins or synthetic resin dispersions and chromic acid compounds as the main ingredients, and coatings that are formed on the surface of metallic materials by chromate treatments containing these synthetic resins, are superior to conventional inorganic chromate coatings in performance properties such as corrosion resistance, adhesion to topcoats, fingerprint resistance, proportion of fixed chromium, lubricity, workability, and appearance. These prior art techniques can be roughly classified as follows according to use.
If about 0.01-2-fold of a synthetic resin material, relative to a conventional inorganic chromate coating, is added to a chromate treatment solution, various performance properties such as corrosion resistance, fingerprint resistance, proportion of fixed chromium, lubricity, and workability can usually be upgraded to the next higher level. Furthermore, if a water-soluble polymer containing large amounts of acrylic acid, maleic acid, etc., with polar groups in the polymer structure is added, especially adhesion to topcoats can usually be improved. Resin-containing chromate treatments in which relatively small amounts of resin materials are incorporated in the inorganic chromate coating, as mentioned above, are considered to be a high-function grade of conventional inorganic chromate treatment.
On the other hand, a synthetic resin-containing chromate treatment coating in which about 2-300-fold of a synthetic resin material is incorporated, based on the chromate coating, is usually formed by applying a mixed solution of a synthetic resin dispersion and an aqueous chromium compound solution on the surface of a substrate metal, followed by drying. A treatment of this kind can sharply improve especially workability, corrosion resistance including worked areas, lubricity, and proportion of fixed chromium, and is considered to be a high-grade treatment that differs a great deal from a conventional inorganic chromate treatment. Treatment agents of this type are differentiated as chromate-containing resinous coating agents, because they generally contain resin materials in very large ratios relative to the chromium compound, and the recent market demand for these agents has greatly increased.
However, when the aforesaid chromate-containing resin coatings are used on an industrial scale, the dispersion stability of the system may in some cases be impaired, as the emulsifier component in the synthetic resin dispersion can be decomposed by oxidation because the chromate ion is a strongly oxidizing material. In fact, there are cases where stable operation has become impossible, because of gelling of the treatment solution, the tendency for sharp increases in viscosity to occur during the coating process with a roll coater, etc. These phenomena tend to occur more frequently when the chromate ion is incorporated in large amounts relative t
Hayashi Yoshihiro
Komiyama Sinobu
Masuko Masashi
Minabe Tatsuro
Harper Stephen D.
Henkel Corporation
Ottmans Andrew L.
Sheehan John
LandOfFree
Water-based surface-treating agent for metallic material does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Water-based surface-treating agent for metallic material, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Water-based surface-treating agent for metallic material will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2822165