Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1995-02-27
2001-01-23
Morris, Terrel (Department: 1771)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S458000, C524S501000, C524S502000, C524S515000, C524S832000, C524S833000
Reexamination Certificate
active
06177493
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a blend composition and a method for the use of such to improve the adhesion properties of coatings.
More particularly, the present invention relates to the use of a polymeric blend containing a macromolecular aqueous dispersion, an acid-functional alkali-soluble resin, and an aminosilane in order to provide adhesion of coatings over difficult surfaces such as chalky substrates.
BACKGROUND OF THE INVENTION
Water-based latex paints have found wide use and acceptance in exterior applications. Water-based latex paints have proven their exterior durability and toughness and, because they are water-based, health, safety and environmental concerns are significantly minimized relative to solvent-based alkyd paints. However, water-based latex paints have inferior adhesion over difficult surfaces such as “chalky substrates” when compared to solvent-based alkyd paints.
Chalky substrates result when the latex paint degrades from exposure to rain and sunlight. The degradation process causes pigments and extenders, such as titanium dioxide and aluminum silicates, to become unbound and to appear on the painted surface as a dusty white chalk. Because of their ability to wet, to penetrate and to adhere to chalky substrates, solvent-based alkyd paints continue to out-perform water-based latex paints over these substrates.
What has been found to be novel and unanticipated is a composition and a method of using such where a polymeric blend containing a macromolecular aqueous dispersion and an acid-functional alkali-soluble resin, and an aminosilane provides adhesion of the latex paint to chalky substrates.
Some of the major advantages of the present invention are that: it minimizes safety, health and environmental concerns by being water-based; it allows for the substitution of a water-based latex paint in a market that was previously dominated by solvent-based alkyd paints; and, the use of the water-based latex system of the present invention over chalky substrates is possible without compromising physical properties such as adhesion.
PRIOR RELATED ART
Although it is generally known to modify the properties of polymers by incorporating functional groups, none of the related art discloses the use of polymeric blends containing a macromolecular aqueous dispersion, an acid-functional alkali-soluble resin, and an aminosilane to provide improved adhesion of latex paints to chalky substrates.
Japanese Patent Application No. J 03-064305A discloses an aqueous silane-modified macromolecular dispersion composition for improving the wet adhesion of adhesives and paints to glass that consists of a carboxyl group-containing water-soluble resin, a macromolecular aqueous dispersion and a water-soluble silane coupling agent containing an amino group. The carboxyl group-containing water-soluble resin has an acid number of 30-800 and the amount compounded are per 100 solid parts by weight of the macromolecular aqueous dispersion, 0.2 to 2.0 parts by weight of the water-soluble resin and 0.1 to 3.0 parts by weight of the amino group-containing silane coupling agent.
U.S. Pat. No. 4,340,524 discloses an acrylic resin latex-based sealant composition with improved water resistance and wet adhesion to glass and aluminum which comprises introducing about 0.1 to about 10 weight percent of an hydrophobic resin dissolved in about 2 to about 20 weight percent of a liquid organic, non-coagulating, non-gelling solvent into the acrylic resin latex together with an aqueous solution of about 0.5 to about 5.0 weight percent of a hydrolyzed organoaminosilane containing sufficient base to maintain a pH of at least 8.5.
International Publication No. WO 92/14788 discloses a composition that provides quasi-crosslinked, alkali-soluble polymeric surface coatings that includes an acid-functional vinyl polymer and an amino-functional siloxane, wherein the vinyl polymer has at least two acid-functional pendant moieties and wherein the siloxane polymer has at least two amino-functional pendant moieties.
U.S. Pat. No. 5,202,378 discloses a polymeric binder exhibiting excellent chalk adhesion wherein the protective coating composition contains a film-forming polymeric binder comprising emulsion copolymerized ethylenically unsaturated monomers including minor amounts of a fatty acid methacrylate or acrylate.
Another way well known in the art to obtain chalk adhesion of latex paints is to blend a solvent-based alkyd into a latex paint. Although this type of blend improves chalk adhesion of the latex paint, the solvent-based alkyd causes undesirable oxidative degradation of the paint film. Various patents including U.S. Pat. No. 4,504,609, U.S. Pat. No. 4,529,765, U.S. Pat. No. 4,199,400 and U.S. Pat. No. 3,454,516, demonstrate the blending of a solvent-based alkyd with a latex for improved chalk adhesion properties.
SUMMARY OF THE INVENTION
One aspect of the invention provides a composition containing a blend of a macromolecular aqueous dispersion latex, an acid-functional alkali-soluble resin, and an aminosilane.
In another aspect of the invention is provided a method for improving the adhesion of latex paint to chalky substrates by combining a macromolecular aqueous dispersion, an acid-functional alkali-soluble polymer, an aminosilane and applying a coating containing the blend of the macromolecular aqueous dispersion, the acid-functional alkali-soluble polymer, and the aminosilane to a chalky substrate.
DETAILED DESCRIPTION
What has been found to be novel and unanticipated is that a composition of a polymeric blend containing a macromolecular aqueous dispersion, an acid-functional alkali-soluble resin, and an aminosilane when used as a binder for a coating provides adhesion to chalky substrates.
In another aspect of the invention is provided a method for improving the adhesion of latex paint to chalky substrates by combining a macromolecular aqueous dispersion, an acid-functional alkali-soluble resin, and an aminosilane and applying the blend of the macromolecular aqueous dispersion, the acid-functional alkali-soluble resin, and the aminosilane, which has been formulated into a coating, to a chalky substrate.
Macromolecular Aqueous Dispersion
The macromolecular aqueous dispersion, also known as a latex or emulsion polymer used in this invention can be any one of many used in architectural coatings-type applications. Suitable monomers for the preparation of polymers to be used in the macromolecular aqueous dispersion according to the invention are olefinically unsaturated compounds which are also employed for the preparation of conventional paint dispersions, such as: esters of acrylic acid or methacrylic acid with alcohols from 1 to 8 carbons, such as, but not limited to, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, butyl methacrylate; vinyl esters such as, but not limited to, vinyl acetate, vinyl propionate, vinyl isobutyrate, vinyl esters of 2-ethyl hexanoic acid, vinyl esters of branched C-9 or C-10 carboxylic acids; monovinyl aromatic compounds such as, but not limited to, styrene and vinyl toluene; vinyl chloride, vinylidene chloride, acrylonitrile and ethylene. Minor amounts of unsaturated monocarboxylic acid, their amides or nitriles such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, acrylamide and methacrylamide can be included. Also included may be a variety of functional monomers in minor amounts including hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, sodium vinyl sulfonate, sodium styrene sulfonate, sulfoethyl methacrylate and acetoacetoxyethyl methacrylate and many others including adhesion promoting monomers, such as disclosed and prepared in accordance with U.S. Pat. Nos. 2,980,652; 4,599,417 and 4,777,265, and by this reference is incorporated herein.
Preferred monomers are those which produce stable dispersions. The quantitative ratios must be selected according to practices well known in the art in such a way that polymers are mad
Guarriello John J.
Morris Terrel
Rohm and Haas Company
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