Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2001-11-28
2004-01-27
Niland, Patrick D. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C428S423100, C428S425900, C428S457000, C428S461000, C428S463000, C428S469000, C523S402000, C523S406000, C523S409000, C523S412000, C523S440000, C524S158000, C524S275000, C524S276000, C524S277000, C524S366000, C524S368000, C524S375000, C524S376000, C524S839000, C524S840000
Reexamination Certificate
active
06683131
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a water-based treatment composition for application to metal surfaces. The treatment composition can be used to form, on the metal surface, resin coatings that exhibit an excellent corrosion resistance in flat areas, an excellent corrosion resistance in damaged areas, and an excellent paint adherence. This invention also relates to surface-treated metal articles of manufacture, particularly metal sheets, on which such a resin coating has been formed.
Zinc- and zinc alloy-plated steel sheet is in wide use, for example, for household electrical appliances and building materials. By itself, zinc-surfaced steel sheet of this type has an inadequate corrosion resistance and paint adherence to its zinc-rich surface and for this reason is typically subjected to a chromate conversion treatment or phosphate conversion treatment prior to being subjected to mechanical forming operations (e.g., press working or bending) and/or being painted. However, a substantial amount of zinc-surfaced sheet is used without being painted.
The type of surface-treated zinc-surfaced steel sheet known as “chromate conversion-coated” has frequently been used in these unpainted applications. However, chromate conversion-coated surfaces suffer from color variations caused by differences in the chromate coating weight and also retain. fingerprint impressions that may be made during forming operations and assembly. Fingerprint-resistant zinc-surfaced steel sheet has been used in order to overcome these problems. This fingerprint-resistant zinc-surfaced steel sheet carries an organic coating formed over the chromate coating. With the goal of preventing fingerprint uptake, this fingerprint-resistant sheet is produced by laying down an organic resin layer with a thickness around 1 micrometre (hereinafter usually abbreviated as “&mgr;m”) after the chromate treatment has been executed on the surface of the zinciferous-plated steel sheet. In addition to fingerprint resistance, the coating on fingerprint-resistant steel sheet must exhibit a variety of properties, such as corrosion resistance, solvent resistance, paint adherence, and damage resistance.
Among these various properties, the ability to resist damage has been in strong demand in recent years. This property is in demand in order to resist the damage to molding surfaces that can be produced when the vibrations generated during the transport of molded articles cause the moldings to rub against one another or to rub against their containers (e.g., cardboard). This makes impairments in quality inevitable, since these damaged areas exhibit a poorer corrosion resistance than ordinary organic-coated zinc-surfaced steel sheet.
In response to this circumstance, various technologies related to surface-treated zinc-surfaced steel sheet have appeared that take into account damage resistance in addition to corrosion resistance and paint adherence. These technologies can be exemplified by the methods described in Japanese Laid Open (Kokai or Unexamined) Patent Application Number Hei 3-17189 (17,189/1991), Japanese Published (Kokoku or Examined) Patent Application Number Hei 6-104799 (104,799/1994), and Japanese Laid Open (Kokai or Unexamined) Patent Application Number Hei 6-292859 (292,859/1994).
Japanese Laid Open (Kokai or Unexamined) Patent Application Number Hei 3-17189 discloses a method that relates to resin coatings comprising fluororesin powder and silica powder blended into urethane-modified polyolefin resin. The characteristic feature of this method resides in the use of the fluororesin powder to protect damaged areas. However, this method requires the use of surfactant in order to generate a uniform dispersion of the fluororesin powder in a water-based solution. The use of this surfactant results in an overall lower level of corrosion resistance and thereby prevents the development of a satisfactory corrosion resistance.
Japanese Published (Kokoku or Examined) Patent Application Number Hei 6-104799 discloses a method that relates to coatings that contain polyester resin, cross-linker, and polyethylene wax with an average molecular weight of 2,000 to 8,000. Due to the use in this method of polyester resin as the base resin, the resulting coating itself has an inadequate resistance to hydrolysis, which again prevents the development of a satisfactory corrosion resistance.
Japanese Laid Open (Kokai or Unexamined) Patent Application Number Hei 6-292859 discloses a method that relates to a coating afforded by the addition of spherical oxidized polyethylene wax powder and chain (coagulated network structure) colloidal silica to resin itself afforded by the addition of ambient temperature-cross-linking epoxy resin to active hydrogen-functional urethane resin. Colloidal silica, upon its adhesion to solid surfaces, functions to raise the friction coefficient—a property known as friction enhancement. In the case of use of chain (coagulated network structure) colloidal silica as in the method under discussion, the damage resistance is impaired by the structure of the colloidal silica itself. This method therefore also uses spherical polyethylene wax, but since this method uses a drying temperature lower than 100° C. the polyethylene wax ends up buried in the resin coating. The lubricity therefore remains inadequate and a satisfactory corrosion resistance at damaged areas cannot be developed.
Thus, as described above, it has not been possible using the heretofore disclosed technologies to produce surface-treated zinc-surfaced steel sheet that exhibits an excellent corrosion resistance and paint adherence and also an excellent corrosion resistance in damaged areas.
Japanese Laid Open (Kokai or Unexamined) Patent Application Number Hei 5-118550 (118,550/1993), Granted Japanese Patent 2,719,571, and Granted Japanese Patent 2,617,838 describe (water-based) lubricating paints that contain urethane resin and/or epoxy resin, silica or silica powder, and wax (including polyethylene wax) and that are used to form resin coatings on cold-rolled steel sheet, zinciferous-plated steel sheet, or aluminiferous metal sheet. The invention described hereinbelow differs from these inventions in having different compositional requirements and different advantageous effects.
This invention is directed to solving the problems associated with the prior art as described above. An object of this invention is to provide a water-based agent, for treating metal surfaces, that can be used to form an organic resin coating that exhibits an excellent corrosion resistance, excellent paint adherence, and in particular an excellent resistance to corrosion in damaged regions. An additional object of this invention is to provide surface-treated metal sheet as afforded by the use of the water-based surface treatment composition according to this invention.
BRIEF SUMMARY OF THE INVENTION
It has been found that these problems can be solved by the use of a water-based surface treatment composition containing urethane resin and/or acrylic resin, curing agent, silica powder, oxidized polyethylene wax of specified particle size, and a compound with a special structure as dispersing agent.
This invention also relates to surface-treated metal sheet that characteristically comprises metal whose surface carries a first layer comprising a chromate coating layer having a coating weight that is 3 to 100 milligrams per square meter (hereinafter usually abbreviated as “mg/m
2
”) as chromium metal and a second layer with a coating weight from 0.3 to 3.0 grams per square meter (hereinafter usually abbreviated as “g/m
2
”) of a resin coating layer that has been formed by the application of the above-described water-based surface treatment composition followed by drying.
DETAILED DESCRIPTION OF THE INVENTION
A water-based treatment composition according to the invention comprises, preferably consists essentially of, or more preferably consists of, water and the following components:
(A) dissolved, dispersed, or both dissolved and dispersed urethane resin, acrylic resin; or both
Kinoshita Yasuhiro
Koyama Takashi
Ueno Keiichi
Cameron Mary K.
Harper Stephen D.
Niland Patrick D.
LandOfFree
Protective coating of metal and product therefrom does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Protective coating of metal and product therefrom, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Protective coating of metal and product therefrom will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3214748