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
1999-11-05
2001-03-13
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...
C524S516000, C524S520000, C524S522000
Reexamination Certificate
active
06201056
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to water-based, one-part, shelf-stable coating compositions made from organic and inorganic materials. The organic materials contain fluorine and offer low surface energy properties. The addition of inorganic materials such as colloidal silica provides abrasion-resistant coatings without adversely affecting the low surface energy properties.
BACKGROUND OF THE INVENTION
Water-based, cross-linkable, fluorochemical low surface energy coating systems made from polymeric surfactants and oxazoline polymer crosslinkers have been described in U.S. Pat. Nos. 5,382,639, 5,294,662, 5,006,624, and 4,764,564.
The present invention has filled a void in providing a low surface energy hard coating system with excellent abrasion resistance. This void has been filled by providing a coating system which integrates a fluorine-containing, crosslinked organic polymeric surfactant with colloidal silica.
SUMMARY OF THE INVENTION
Accordingly, the present invention is a water-based composition comprising an aqueous solution, emulsion, or dispersion of: (a) a water-soluble or water-dispersible polymer or oligomer having at least one anionic moiety which is capable of reacting with an oxazoline or oxazine moiety; (b) a water-soluble or water-dispersible polymer or oligomer having at least one oxazoline or oxazine moiety; and (c) colloidal silica. At least one of polymers or oligomers (a) and (b) has at least one fluoroaliphatic moiety, and either polymer or oligomer (a) or (b) (or both) can further contain at least one silyl moiety. Preferably, the fluorine content of the composition is at least about 10 weight percent.
Thus, for example, an especially preferred embodiment in a water-based composition includes an aqueous solution, emulsion, or dispersion of
(a) a water-soluble or water-dispersible polymer or oligomer having interpolymerized units derived from at least one fluoroaliphatic-radical containing acrylate, at least one carboxy-containing monomer, and at least one silyl moiety derived from a trialkoxysilylalkyl acrylate or methacrylate or trialkoxysilylalkyl mercaptan in which alkyl has from 1 to about 10 carbon atoms and alkoxy has from 1 to about 3 carbon atoms;
(b) a water-soluble or water-dispersible polymer or oligomer having at least one oxazoline or oxazine moiety; and
(c) colloidal silica having an average particle diameter of at least about 5 nanometers.
A second aspect of the invention is a coating comprising the cured composition, which comprises crosslinked polymer (e.g., containing at least one amide-ester crosslink moiety derived from the reaction of carboxyl groups with oxazoline or oxazine moieties) having colloidal silica integrated therein.
A third aspect of the present invention is a coated article comprising the coating.
The coating compositions can be used to provide a low surface energy hard coat to protect smooth, flat surfaces of essentially any kind (e.g., poly(vinyl chloride), polycarbonate, polyester, nylon, metals (either painted or bare), glass, wood, stone, etc.). The good abrasion resistance properties will protect such surfaces from physical damage, and the low surface energy properties will provide easily cleanable and possibly antigraffiti properties. The coating can also be used as a low adhesion backsize for adhesives.
The significant difference of the present invention over related technologies is the incorporation of colloidal silica into the coating composition. The previous organic polymer-based coating systems have been transformed into organic-inorganic composite compositions. The finished coatings therefore become much more abrasion-resistant and are more durable in protective applications. Unexpectedly, the antigraffiti and release properties of the coating systems are also not degraded despite the incorporation of the high surface energy, hydrophilic, colloidal silica, even with compositions containing a lower weight percentage of fluorine in many cases.
DETAILED DESCRIPTION OF THE INVENTION
As used herein “anionic” means capable of forming anions in aqueous media. As used herein, “copolymers” or “polymers” includes polymers and oligomers.
The anionic moiety-containing polymers useful in this invention preferably have an average of more than two reactive ionic moieties per polymer. Preferably, the anionic moiety-containing polymers have an average of more than one fluoroaliphatic moiety per polymer. Such polymers include those described, for example, in U.S. Pat. Nos. 5,382,639, 5,294,662, 5,006,624 and 4,764,564 supra, which descriptions are incorporated herein by reference.
Useful anionic moieties include carboxy and mercaptan moieties, which can be reacted with bases to obtain carboxylate and mercaptide salts. At lower pH values, these moieties become essentially nonionic. The particularly preferred anionic moiety is carboxylate. The carboxylate anionic polymer can be utilized in the water-based compositions of this invention as its ammonium salts.
The anionic moiety-containing polymers, polymer component, or surfactant, useful in the present invention, can be prepared, for example, by the addition polymerization of one or more ethylenically unsaturated carboxy-containing monomers (e.g., acrylic acid, methacrylic acid, and esters thereof such as 2-carboxyethyl acrylate) with one or more ethylenically unsaturated comonomers (e.g., acrylic esters, vinyl ethers, or styrenic monomers). The comonomers can be further substituted with fluorine. The carboxy-containing monomer is preferably acrylic acid (due to stability considerations) or 2-carboxyethyl acrylate (due to crosslinking considerations). Preferably, the anionic moiety-containing polymers further contain a fluoroaliphatic radical-containing, ethylenically unsaturated monomer, such as perfluoroalkyl acrylate esters, e.g., CH
2
═CHCOOCH
2
CH
2
N(Et)SO
2
C
8
F
17
, or fluoroalkyl vinyl ethers, e.g., CH
2
═CHOCH
2
C
7
F
15
, which can be incorporated into the anionic moiety-containing polymer by addition polymerization.
The oxazine or oxazoline polymers or oligomers useful in the present invention can be prepared by the addition polymerization of an oxazine-or oxazoline-containing ethylenically unsaturated monomer, such as 2-isopropenyl-2-oxazoline (IPO) and those represented by the general structures:
wherein R
1
is an unsaturated organic radical capable of addition polymerization, such as 1,2-ethylenic unsaturation. Preferably, R
1
is an isopropenyl group. Each R
2
is independently hydrogen, halogen, or a substituted organic radical, preferably R
2
is hydrogen. Optionally an aliphatic or fluoroaliphatic radical-containing, ethylenically unsaturated monomer, such as acrylate esters, e.g., CH
2
═CHCO
2
CH
2
CH
2
N(Et)SO
2
C
8
F
17
, vinyl ether, or styrenic monomers can be copolymerized with the oxazine- or oxazoline-containing ethylenically unsaturated monomer.
The oxazoline- or oxazine-containing polymers useful in the present invention preferably have an average of more than two oxazoline or oxazine moieties per polymer. If desired, aziridine group-containing oligomers can be utilized in place of the oxazoline- or oxazine-containing polymers or oligomers, provided that shelf stability or one-part formulation is not required.
The aliphatic moiety of the aliphatic radical-containing monomer, if present, can be a monovalent aliphatic or alicyclic moiety, preferably saturated. It can be linear, branched, cyclic, or combinations thereof. It can contain catenary, i.e., in-chain, heteroatoms bonded only to carbon atoms, such as oxygen, divalent or hexavalent sulfur, or nitrogen. The aliphatic moiety has from 1 to about 20 carbon atoms, preferably from 1 to about 10 carbon atoms.
The fluoroaliphatic moiety of the fluoroaliphatic radical-containing monomer, if present, can be a fluorinated, stable, inert, preferably saturated, non-polar, monovalent aliphatic or alicyclic moiety. It can be straight chain, branched chain, cyclic, or combinations thereof. It can contain catenary heteroatoms, bonded only to carbon atoms, such as oxygen, divale
3M Innovative Properties Company
Egwim K C
Weiss Lucy C.
Wu David W.
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