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
2002-10-08
2004-04-27
Wu, David W. (Department: 1713)
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...
C524S431000, C524S437000, C524S261000, C524S265000, C524S266000, C526S307600, C526S307700, C525S237000, C428S422800
Reexamination Certificate
active
06727309
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a wet emulsion finish composition useful for providing a coating or film to a substrate surface such as a floor. More particularly, it relates to an emulsion finish composition incorporating surface modified inorganic particles providing enhanced shelf stability and film performance, and methods of preparing the same.
Polymer compositions are used in the formulation of various coating compositions such as floor finishes or polishes, for example. Commercially available floor finish compositions typically are aqueous emulsion-based polymer compositions comprising one or more organic solvents, plasticizers, coating aides, anti-foaming agents, polymer emulsions, metal complexing agents, waxes, and the like. The polymer composition is applied to a floor surface and then allowed to dry in air, normally at ambient temperature and humidity. A film is formed that serves as a protective barrier against soil deposited on the floor by pedestrian traffic, for example. These same polymer compositions can be applied to other substrate surfaces for which protection is desired, such as tile floors, walls, furniture, windows, counter tops, and bathroom surfaces, to name but a few.
Although many of the commercially available aqueous floor finishes have performed well and have experienced at least some commercial success, opportunities for improvement remain. In particular, it is highly desirable that the resultant floor finish film exhibits certain physical and performance characteristics including hardness, scratch resistance, soil resistance, black marks/scuff resistance, and abrasion resistance. Unfortunately, for applications in which an enhanced floor finish film hardness or resistance to deterioration is of great importance, currently available aqueous floor finish compositions may be less than satisfactory.
A primary factor in finish film hardness is the emulsion polymer formulation. A metal complexing agent included in the floor finish composition ionically bonds to the polymers when the composition is dried, resulting in the protective film. This reaction is reversible and the film is easily removed by a stripper solution when desired. In this regard, most aqueous floor finish polymer emulsions are polyacrylate-based. While other polymers (e.g., styrene) substituted for, or combined with, the acrylic polymer and/or additives such as coalescing agents or plasticizers can affect the resultant film hardness, only marginal improvements are typically achieved. Because resultant film hardness and deterioration resistance are a function of the types of solids within the formed film, a more viable approach may be to add hard, inorganic particles to the emulsion polymer matrix. In theory, these inorganic particles would increase the resulting film hardness, making the finish harder and improving properties such as scratch resistance and soil resistance. While promising, simply adding these particles does not result in a commercially viable product. In particular, the inorganic particles will not remain dispersed in the wet polymer composition, but instead readily precipitate (see Comparative Example 1 below).
Floor finish manufacturers continually strive to provide improved hardness, abrasion resistance, and soil resistance properties. To this end, the addition of inorganic, hard particles appears promising. Unfortunately, current efforts have not produced a shelf stable product. Thus, a need exists for a surface finish composition exhibiting enhanced bulk properties via inorganic nanoparticles that will not precipitate over extended periods of time.
SUMMARY OF THE INVENTION
One aspect of the present invention provides an aqueous surface finish composition comprising a film-forming, reversibly crosslinked, emulsion-based polymer composition, and a surface modified inorganic particle material. The surface modified inorganic particle material is dispersed within the polymer matrix, and enhances performance characteristics of a film produced by the composition following application to a surface, including hardness, modulus, and scratch and soil resistance. The composition is particularly well suited for application to floor surfaces, but also to other substrate surfaces such as walls, counter tops, furniture, windows, and bathroom surfaces.
Typically, the surface modified inorganic particle material consists of particles surface modified by a coupling agent. In general terms, the coupling agent stabilizes the inorganic particles within the aqueous polymer composition, and renders the inorganic particles compatible with the polymer composition once dried. Preferably, the surface modified inorganic particle material comprises silica nanoparticles surface modified by a silane coupling agent. The ratio (by weight) of emulsion polymer composition solids to surface modified inorganic particle material solids is preferably in the range of 1:1-10:1, more preferably 3:1-5:1.
Polymers of the polymer composition are preferably acrylic polymers, acrylic copolymers, styrene-acrylic copolymers, or blends thereof. In one preferred embodiment, the polymer component is a blend of an acrylic polymer and a urethane polymer, or alternatively, acrylic urethane copolymers, with the urethane enhancing the toughness of the resultant film. The finish composition can also contain certain alkali soluble resins, waxes, permanent and fugitive plasticizers, defoamers, wetting agents, metal complexing agents and biocides.
Another aspect of the present invention provides a process for improving the performance of an emulsion-based polymer surface finish composition by dispersing a surface modified inorganic particle material within the polymer matrix. Another aspect of the present invention relates to a method of preparing the surface finish composition of the present invention.
DETAILED DESCRIPTION OF THE PREFFERED EMBODIMENTS
The present invention provides an aqueous surface finish composition comprising a film-forming emulsion based polymer composition and a surface modified inorganic particle material dispersed within the polymer composition. The finish composition can be applied to a variety of substrates such as, for example, floor, wall, counter top, furniture, window, and bathroom surfaces. Preferably, the substrate is a floor, but can be any surface upon which the coatable compositions of the present invention can be applied such as vinyl, ceramic, wood, marble, and the like. The resultant coatings are smooth, exhibit increased hardness and modulus, and are highly resistant to scratches and soil. The inorganic particles provide for these performance enhancements, with the surface modification thereof ensuring long-term shelf stability of the finish composition.
Individual components of the emulsion-based polymer composition are described in greater detail below. In general terms, however, the polymer composition preferably includes an acrylic polymer and a metal complexing agent suspended in water. With this in mind, the inorganic particles are surface modified to ensure long-term suspension within the polymer composition. In a preferred embodiment, the surface modified inorganic particle material consists of a plurality of ceramic-type particles modified by a coupling agent. More preferably, the inorganic particles are metal oxide particles in any oxidation state. Examples of preferred metal oxides include silica, alumina, zirconia, vanadia, titania, ceria, iron oxide, antimony oxide, tin oxide, alumina/silica and combinations thereof, with silica being the most preferred. Regardless of the exact material employed, the inorganic particles are preferably nanoparticles having an average particle size (diameter) of 5-150 nm. Nanoparticles maintain transparency of the floor finish coating.
“Surface modification” of the inorganic particles is characterized by the provision of a coupling agent that modifies at least a portion of a surface of each particle. The term “surface modified particle” refers to a particle that includes surface groups attached to the surface
Kolb Brant U.
Paiva Adriana
Yarmey Susan K.
Edman Sean J.
Sastri Satya
Wu David W.
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