Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From reactant having at least one -n=c=x group as well as...
Reexamination Certificate
2001-09-21
2003-09-23
Gorr, Rachel (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From reactant having at least one -n=c=x group as well as...
C528S071000, C528S073000, C524S591000, C427S385500, C428S423100
Reexamination Certificate
active
06624276
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to a curable polyurethane material, coatings prepared therefrom, and methods of making the same.
BACKGROUND OF THE INVENTION
Coating formulations find use in various industries including the coating and/or painting of motor vehicles. In these industries, and in the automotive industry in particular, considerable efforts have been expended to develop coating compositions with improved performance properties. In the automotive industry, for example, numerous approaches have been advanced to achieve improved chip resistance and corrosion protection. These efforts have included, for example, applying up to 6 or more individually applied coating layers over the substrate by one or more coating methods.
These coatings may be applied by either electrophoretic or non-electrophoretic coating methods. Electrodeposition has become increasingly important in the coatings industry because, by comparison with non-electrophoretic coating means, electrodeposition offers higher paint utilization, outstanding corrosion protection, low environmental contamination, and a highly automated process. Generally, cationic electrodeposited coatings provide better corrosion resistance than anionic electrodeposited coatings. Non-electrophoretic coatings, such as sprayable coatings, however, are still widely used throughout the coatings industry because of the relatively low equipment and operating costs associated therewith.
Such efforts have resulted in increased protection of the surface of the substrate and reduced paint loss through chipping when the substrate of the vehicle is hit with solid debris such as gravel and stones. By reducing the difference in impact energy between multiple coating layers, it is believed that chip resistance of the overall coating can be improved, especially for coatings in which the respective coating layers have excessive differences in hardness. It is believed that reducing the hardness differential can lessen delamination between the coating layers such as between the undercoat, an intermediate coat, and a topcoat or an undercoat and an intermediate coat.
In U.S. Pat. No. 5,047,294, this differential is said to be reduced by applying a crosslinked polyurethane resin filler composition between coating layers to improve intercoat adhesion. The filler composition includes a water-dispersible polymer derived from polyisocyanates, high and low molecular weight polyols, compounds reactive with the isocyanate, and monofunctional or active hydrogen-containing compounds. Anhydrides of carboxylic acids, such as trimellitic acid, are disclosed as useful to form the high molecular weight polyol. The coating formulation is typically applied as an intermediate coat between the primer and the topcoat to even out irregularities present in the primer, and improve the overall stone-chip resistance of the coating.
In U.S. Pat. No. 5,674,560, a chip resistant polyolefin type of primer is spray applied over a cationic or anionic electrodeposited coated film before application of a soft intermediate polyester film. The reduction of the differential in impact energy is reportedly maximized when the polyolefin primer is applied over the softer anionic electrodeposited film as opposed to a cationic electrodeposited film.
Even though electrophoretic coatings can provide many advantages over non-electrophoretic coatings, improvements to each are still sought because of the widespread use of both.
Accordingly, the need exists for a polyurethane material useful in coating compositions that can and may be applied to the substrate by electrophoretic and non-electrophoretic coating methods.
SUMMARY OF THE INVENTION
The present invention provides an anionic self-crosslinkable polyurethane material, the polyurethane material having a weight average molecular weight of less than 15,000 grams per mole, wherein the polyurethane material, when cured, has a toughness of at least 20 MPa according to TOUGHNESS TEST METHOD at a temperature of 25° C.
In one embodiment, the polyurethane material comprises isocyanate functional groups, the isocyanate functional groups blocked with a blocking agent. In another embodiment, the polyurethane material is anionic.
The present invention is also directed to a primer coating composition, a basecoat composition, a clearcoat composition, a monocoat composition, and a multicomponent composite coating including the polyurethane material described above. Where the present invention is a multicomponent composite composition, at least one of the layers comprises the polyurethane material.
The present invention is also directed to a coated substrate having coated layers applied thereover, at least one of the coated layers comprising the polyurethane material of the present invention.
The present invention is also directed to a process for forming an aqueous composition comprising an anionic self-crosslinkable polyurethane material, the process comprising:
(a) forming the polyurethane material, the polyurethane material having a weight average molecular weight of less than 15,000 grams per mole, wherein the polyurethane material, when cured, has a toughness of at least 20 MPa according to TOUGHNESS TEST METHOD at a temperature of 25° C.; and
(b) dispersing the polyurethane material in water to form an aqueous composition.
The present invention is also directed to a process for preparing a coated substrate, comprising,
(a) forming a coating on the substrate, the coating being a composition comprising an anionic self-crosslinkable polyurethane material, the polyurethane material having a weight average molecular weight of less than 15,000 grams per mole, wherein the polyurethane material, when cured, has a toughness of at least 20 MPa according to TOUGHNESS TEST METHOD at a temperature of 25° C.; and
(b) at least partially curing the coating.
DETAILED DESCRIPTION OF THE INVENTION
Other than in the operating examples, or unless otherwise expressly specified, all of the numerical ranges, amounts, values and percentages such as those for amounts of materials, times and temperatures of reaction, ratios of amounts, values for molecular weight (whether number average molecular weight (“M
n
”) or weight average molecular weight (“M
w
”)), and others in the following portion of the specification may be read as if prefaced by the word “about” even though the term “about” may not expressly appear with the value, amount or range. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.
Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Furthermore, when numerical ranges of varying scope are set forth herein, it is contemplated that any combination of these values inclusive of the recited values may be used.
Any numeric references to amounts, unless otherwise specified, are “by weight”. The term “equivalent weight” is a calculated value based on the relative amounts of the various ingredients used in making the specified material and is based on the solids of the specified material. The relative amounts are those that result in the theoretical weight in grams of the material, like a polymer, produced from the ingredients and give a theoretical number of the particular functional group that is present in the resulting polymer. The theoretical polymer
Lamers Paul H.
Martz Jonathan T.
Meyers Lawrence D.
Novak Carolyn A.
Olson Kurt G.
Altman Deborah M.
Gorr Rachel
PPG Industries Ohio Inc.
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