Stock material or miscellaneous articles – Composite – Of polyamidoester
Reexamination Certificate
2001-11-26
2004-08-03
Tucker, Philip (Department: 1712)
Stock material or miscellaneous articles
Composite
Of polyamidoester
C428S340000, C428S413000, C428S418000, C427S385500, C524S589000, C524S590000, C524S591000
Reexamination Certificate
active
06770373
ABSTRACT:
FIELD OF TECHNOLOGY
The present invention relates to a water-based metal surface treatment composition for forming a lubricating film with excellent marring resistance.
BACKGROUND TECHNOLOGY
Manufacturers of home electrical appliances, automobiles, building materials, and so forth have often made use of cold-rolled or galvanized sheet steel in the past, and these sheets are most often painted after undergoing press molding or other such forming. Some materials, however, do not lend themselves well to forming, so the desired formability is achieved by coating them with a lubricating oil, typically a press oil, in the course of the forming. When this forming is to be followed by painting, the applied lubricant must be one that can be removed in a degreasing process.
Accordingly, in an effort to reduce the number of steps entailed, lower the cost, and improve the working environment, manufacturers have been offering sheet steel that comes already coated with a wax-based lubricant, so that a press oil need not be used. A wax-based lubricant, however, must be removed in a subsequent degreasing process, and while this is indeed an improvement over using a press oil in terms of the press environment, there is still room for improvement. Functional surface treated sheet steel having a better lubricated surface has therefore been developed. This sheet steel is coated with a thin film of a composition whose main component is an organic resin with good lubricity, and can therefore be formed without having to be coated with a press oil or other lubricant, and furthermore this surface treated sheet steel does not need to undergo any subsequent degreasing or undercoating treatment.
Prior art pertaining to this functional surface treated sheet steel has been disclosed in (1) Japanese Laid-Open Patent Applications S61-231177, S61-279687, and S62-33781, (2) Japanese Laid-Open Patent Application S62-289274, (3) Japanese Laid-Open Patent Application S60-103185, (4) Japanese Patent Publication H6-92567, (5) Japanese Patent Publication H6-104799, and (6) Japanese Laid-Open Patent Application H6-292859, which will be summarized below.
The art disclosed in the publications of (1) is related to a surface treated steel sheet, characterized in that a film, comprising a silane coupling agent and/or a titanium coupling agent, a chromate, silica sol, a microparticle coloring pigment, and a solid lubricant contained in an emulsion polymer composed of a monomer expressed by the general formula CH
2
═CR
1
—COOR
2
, an &agr;,&bgr;-unsaturated carboxylic acid monomer, and a monomer that is copolymerizable with these, is formed on the steel sheet surface. A film obtained in this manner is effective for relatively light forming, such as bending and offsetting, but during intense working such as squeezing and drawing, typified by press forming, a sliding surface temperature can exceed 100° C., at which point the resin film layer is prone to separation, and resin dust clings to the surfaces of the mold or press formed article, which adversely affects the appearance of the formed article.
The publication disclosed in (2) is characterized in that a film layer whose main component is a composite or mixture of a urethane-based resin and silicon dioxide is provided over a galvanized steel sheet. Here, the term “urethane resin” refers to a mixture of a urethane resin and another resin (such as epoxy, acrylic, or phenol). The film obtained in this manner is effective in forming that involves low-speed sliding (10 mm/sec or less), but film separation occurs in press forming and other high-speed sliding forming (approximately 500 mm/sec), so the targeted high lubricity cannot be achieved.
The publication disclosed in (3) relates to a two-layer chromate treated steel sheet, characterized in that a special chromate layer is provided over a steel sheet plated with zinc or a zinc compound, and over this is formed a composite chromate film composed of an amino-terminated urethane modified epoxy resin, a silicone resin, molybdenum disulfide, a polyolefin wax, a chromate-based rustproof pigment, and composite aluminum phosphate. Because this film makes use of a self-crosslinking type of amino-terminated urethane modified epoxy resin, relatively stable performance can be obtained even without a crosslinking agent, but the targeted level of performance cannot be achieved.
The publication disclosed in (4) is characterized in that an electroconductive substance, a chromium compound, and a lubricating substance are compounded with a resin composition composed of a resin selected from among epoxy resins, polyester resins, and acrylic resins, and a polyisocyanate or an amino resin that serves as a hardener component. With a film obtained in this manner, the targeted marring resistance during high-speed sliding cannot be achieved because the wear resistance of the film itself is inadequate.
The publication disclosed in (5) is characterized in that a film comprising a polyethylene wax with an average molecular weight of 2000 to 8000 contained in a polyester resin and a crosslinking agent is formed over the surface of a steel sheet. With a film obtained in this manner, the targeted level of performance (corrosion resistance and paint adhesion) cannot be achieved because the hydrolysis resistance of the film itself is inadequate.
The publication disclosed in (6) is characterized in that a film containing a urethane resin having active hydrogen in its molecules, an epoxy resin of the type that crosslinks at normal temperature, spherical polyethylene wax, and linear colloidal silica is formed over the surface of a steel sheet. There are no restrictions on the urethane resin used for this film, and there are numerous cases when the performance of the resulting film does not meet the targeted level.
Therefore, at present there has yet to be obtained a water-based paint composition that has good marring resistance during intense working, as well as excellent corrosion resistance and paint adhesion.
DISCLOSURE OF THE INVENTION
The present invention was conceived in an effort to solve the above-mentioned problems encountered with prior art, and it is an object thereof to provide a water-based lubricating paint composition for a highly functional surface treated sheet that has good marring resistance during intense working, as well as excellent corrosion resistance and paint adhesion.
As a result of diligent research aimed at solving the above-mentioned problems encountered with prior art, the inventors perfected the present invention upon discovering that it is favorable to use a water-based metal surface treatment composition containing a water-based urethane resin with a specific structure, a hardener, silica, and a polyolefin wax.
Specifically, the present invention provides a water-based metal surface treatment composition for forming a lubricating film with excellent marring resistance, characterized by containing (a) a water-based urethane wax, in which average molecular weight of the water-based urethane is at least 3000 and the resin skeleton includes a bisphenol skeleton and a carboxyl group, the content of nitrogen participating in an isocyanate reaction during the synthesis of said resin is between 2 and 13 wt %, and the ratio of the nitrogen in urea bonds to the nitrogen participating in the isocyanate reaction, which is the proportion of nitrogen atoms pertaining to urea bonds out of the nitrogen atoms participating in the isocyanate reaction during the synthesis of said resin, is between 10/100 and 90/100; (b) a hardener; (c) silica; and (d) a polyolefin wax, wherein the combined amount of components (a) and (b), as solids with respect to the total solid weight (e), is 50 to 95 wt %, the equivalent ratio of functional groups in component (b) with respect to the equivalent of carboxyl groups contained in the skeleton of component (a) is 0.10 to 1.00, the solid weight of component (c) with respect to (e) is 3 to 40 wt %, and the solid weight of component (d) with respect to (e) is 2 to 30 wt %.
The nitrogen content of the water-b
Kinoshita Yasuhiro
Morita Ryoji
Cameron Mary K.
Feely Michael
Harper Stephen D.
Henkel Corporation
Tucker Philip
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