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
2000-03-03
2002-06-04
Michl, Paul R. (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...
Reexamination Certificate
active
06399689
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a composition and method for forming abrasion resistant coatings. More particularly, this invention is directed to novel coating compositions containing a sol gel aluminum oxide grain in amounts sufficient to provide coatings exhibiting enhanced abrasion resistance.
BACKGROUND AND SUMMARY OF THE INVENTION
The application of protective or decorative coatings is a common processing step in many manufacturing protocols. One important functional property of such coatings, whether they be applied for a decorative or a protective function, is abrasion resistance. Disruption of the integrity of the applied coatings by abrasive contact with other surfaces during shipment or in the ordinary use of the coated surfaces can affect the appearance of the coatings and their effectiveness in protecting the underlying surface. Accordingly, there has been a significant research and development effort directed to the formulation of coating compositions which exhibit abrasion resistance along with other desirable coating characteristics such as flexibility, hardness, adhesion, transparency, translucency, and the like.
Abrasion resistance is a particularly important and desirable property for coating formulations used on surfaces which in use are subjected to abrasive contacts with other objects, such as flooring, shelving and the like. The use of coatings exhibiting good abrasion resistance on such surfaces prolongs both the appearance and the functionality of the coating compositions.
Therefore, in accordance with this invention there is provided a coating composition for forming abrasion resistant coatings. The invention is based, at least in part, on the discovery that the use of a sol gel process grain or grain composition as an additive at effective levels in a resin coating composition provide coatings exhibiting surprisingly enhanced abrasion resistance.
Typical coating compositions in accordance with this invention comprise a film-forming resin composition and a sol gel process ceramic grain composition wherein the ceramic grain contains aluminum oxide and wherein the aluminum oxide grain forms about 1 to about 60 percent by weight of the coating. The film-forming resin component of the present coating composition is preferably a thermosetting or UV-curable resin of the type used in decorative and protective coating compositions.
In another embodiment of the present invention improved abrasion resistant surface finishes are applied in a coating protocol utilizing at least one sealer or primer coating composition to form a sealer coat and at least one top coat composition to form a surface top coat. The improved surface finish and method comprises using an improved sealer and/or top coating composition comprising a film-forming resin composition and a sol gel processed ceramic grain in an amount effective to impart abrasion resistance to the surface finish.
DETAILED DESCRIPTION OF THE INVENTION
In accordance with one embodiment of this invention there is provided a curable coating composition for forming abrasion-resistant coatings. The coating composition comprises a film-forming resin composition, most typically a thermosetting resin or a UV-curable resin, and a sol gel processed grain composition. The film-forming resin composition is formulated to include an amount of a sol gel ceramic grain composition sufficient to enhance the abrasion resistance in the resulting cured coatings.
In one embodiment of the invention the film-forming resin of the present coating composition is a thermosetting resin composition comprising epoxy resins, acrylic resins, polyester resins, urea resins, melamine resins or polyurethane resins.
In another embodiment of the invention the film-forming resin composition comprises a UV-curable resin, typically a UV-curable resin comprising olefin-functional monomers and olefin-functional oligomers and polymers. Typically such formulations include a combination of mono- and multi-functional olefin oligomers or polymers. See, for example, the disclosures of U.S. Pat. Nos. 4,600,649; 4,902,975; 4,900,763; and 4,065,587, the disclosures of which are incorporated herein by reference. In one preferred embodiment of the invention there is provided a coating for forming abrasion resistant coating compositions, particularly for wood floor applications, wherein the coating composition comprises mono-olefin functional and multi-olefin functional polyurethane monomers, oligomers and polymers.
Typically the present coating compositions comprise about 40 to about 90 percent by weight of a film-forming resin composition and about 10 to about 60 weight percent of a sol gel process ceramic grain, typically an aluminum oxide composition. Of course, such coating compositions can, and typically do, include other standard coating additives such as resin-dependent curing agents or catalysts, flow aids, wetting agents, dispersing agents, pigments, dyes, fillers, fibers, antistatic agents, lubricants, surfactants, plasticizers, rheology modifiers, and coupling agents. Thus, for example, coating compositions of this invention utilizing UV-curable resins typically include effective amounts (about 0.1 to about 3 percent by weight) of one or more photoinitiators. Such compositions can be cured by electron beam irradiation without photoinitiators.
The coating composition may also, for example, contain a coupling agent. Exemplary of such coupling agents suitable for use in this invention include organo silanes, zircoaluminates and titanates. The coupling agent may be added directly to the coating composition. Alternatively, the ceramic grain may be pre-treated with the coupling agent before the grain is added to the coating composition. The coupling agent is added in an amount typically between 0.1 to 5% by weight of the ceramic particle weight.
The mineral component of the present coating compositions comprises a form of alumina made by sol gel processing. These products, sometimes referred to as sol gel process ceramic grain are commercially available from several sources. In one embodiment of the invention the sol gel processed alumina grain is a product sold under the name Cubitron® by 3M Corporation.
Sol gel processed grain compositions such as those for use in accordance with this invention are often specified, inter alia, by grain size, ranging from about JIS 240 down to JIS 8000. These grain sizes correspond to a particle size range from about 130 &mgr;m down to about 0.5 &mgr;m. The sol process grain component of the present composition can be of a homogeneous grain size or several grain sizes in combination. In one embodiment of the present invention, the sol gel process grain forms about 1 to about 60 percent by weight of the coating, more typically about 10 to about 40 percent by weight of the coating with a grain size of JIS 320 or smaller. In one embodiment, JIS 400 sol gel process aluminum oxide grain is used alone or in combination with smaller and/or larger grain size material. Sealer coats/primer coats in accordance with the present invention typically have higher weight percents of the grain composition than grain-filled top coat compositions. Top coat compositions are usually formulated to contain about 1 to about 15 percent of the sol gel processed grain while sealer/primer coat composition are most typically formulated to contain about 10 to about 40, more preferably about 10 to about 30 percent by weight of the sol gel process grain.
The ceramic grain particles may also contain a surface coating. Surface coatings are known to improve the adhesion between the ceramic particle and the film-forming resin composition binder in abrasive articles. Such surface coatings are described in U.S. Pat. Nos. 5,011,508; 1,910,444; 3,041,156; 5,009,675; 4,997,461; and 5,213, 951.
The coating compositions of the present invention are applied using art-recognized coating application techniques including spray coating, curtain coating, reverse roll coating, vacuum coating, extrusion coating, or direct or differential roll coating applications
Barnes & Thornburg
Lilly Industries, Inc.
Michl Paul R.
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