Compositions: coating or plastic – Coating or plastic compositions – Carbohydrate or derivative containing
Reexamination Certificate
2000-09-25
2002-11-12
Brunsman, David (Department: 1755)
Compositions: coating or plastic
Coating or plastic compositions
Carbohydrate or derivative containing
C106S163010, C106S169550, C106S201100, C106S204010, C106S204300, C106S287140, C106S287150, C106S287340, C106S287350, C523S218000, C524S001000, C524S492000, C524S493000, C428S403000, C428S404000, C428S405000
Reexamination Certificate
active
06478864
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a surface coating composition that is characterized by moisture and chemical resistance and a method of imparting such characteristics to a surface coating composition.
BACKGROUND OF THE INVENTION
Metal oxides, particularly dry silica gels, have been incorporated into certain surface coating materials in order to achieve the impression of “mattness.” A wet film applied to a substrate is initially held flat and therefore glossy by the forces of surface tension. As the film dries and cures, the increasing viscoelasticity associated with the sol-gel transition hinders the movement of particles into the film, and the surface deforms to accommodate the matting agent particles. This roughness is maintained in the solidified film, which then is characterized by a matt finish. While the matting effect attributable to certain silica gels produces a desirable surface appearance for some applications, a surface coating composition desirably possesses additional properties, such as moisture resistance, in order to enhance its utility for a variety of applications.
Moisture resistance is a characteristic of a composition such that the composition resists damage after wetting by or absorption of water. Prior attempts at rendering a surface coating composition moisture resistant have focused on the hydrophobic modification of the silica aerogel. Silica xerogels, for example, have been rendered hydrophobic by esterification with organic alcohols at high temperatures or by physical adsorption of organic polymers. While such agents may impart a degree of hydrophobicity to the silica aerogel, these surface materials remain reactive and can be lost from the xerogel in the presence of other reactive species, such as alcohols and water. The moisture resistance properties imparted to the composition by the silica gel, if any, can be accordingly degraded when the composition is exposed to other chemical agents. Such exposure to other chemical agents, such as alcohols, often occurs when the composition is a surface coating, such as a coating on wood furniture.
Thus, there remains a need for surface coating compositions that provide a matting effect while also imparting moisture and chemical resistance to substrates. The present invention seeks to provide such a surface coating composition. These and other advantages of the present invention, as well as additional inventive features, will be apparent from the description of the invention provided herein.
BRIEF SUMMARY OF THE INVENTION
The present invention provides a surface coating composition comprising a resin system, and a hydrophobic metal oxide, wherein said composition, after application to a substrate, is characterized by (a) a moisture resistance which is retained for at least about 6 months, (b) a resistance to a 50% w/w ethanol/water solution, and (c) a gloss level of about 50 gloss units or less.
The present invention also provides a method of matting a surface coating composition and enhancing the moisture and chemical resistance of the composition comprising (i) providing a hydrophobic metal oxide which imparts to the composition, after application to a substrate, (a) a moisture resistance which is retained for at least about 6 months, (b) a resistance to a 50% w/w ethanol/water solution, and (c) a gloss level of less than 50 gloss units, and (ii) mixing the metal oxide with a resin system to form the surface coating composition.
The present invention further provides a substrate having a surface coated with the surface coating composition of the present invention, as well as a method of treating a substrate with the present inventive surface coating composition.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention provides a surface coating composition comprising a resin system, and a hydrophobic metal oxide. The composition, after application to a substrate, is characterized by (a) a moisture resistance which is retained for at least about 6 months, (b) a resistance to an organic alcohol solution, particularly a resistance to a 50% w/w ethanol/water solution, and (c) a gloss level of 50 gloss units or less.
The resin system can comprise any suitable resin. Thus, the resin can be any resin known by those of skill in the art to be suitable for use in a surface coating composition. Suitable resins include, for example, polyesters, epoxies, urethanes, cellulosics, alkyds, acrylics, and mixtures and precursors thereof. Suitable acrylic resins for use in the composition of the present invention include those known as WORLEE CRYL A 1220 (E.H. Worlee & Co., Germany) and NEOCRYL A-633 (Zeneca Resins, Wilmington, Mass.).
Preferably, the resin is a nitrocellulose or a nitrocellulose alkyd. Suitable nitrocellulose resins include LANCO CL-600 (Lanco Manufacturing Corporation, San Lorenzo, Calif.), and cellulose nitrate. Among the useful alkyd resins are those known as WORLEEKYD T36 (E.H. Worlee & Co, Germany).
Any suitable amount of resin can be present in the surface coating composition. The resin is preferably present in the surface coating composition in an amount of about 10-95% w/w.
Any suitable metal oxide can be used in the context of the present invention. Suitable metal oxides include silica, alumina, titania, zirconia, ceria, and magnesia. The metal oxide preferably is silica, such as, for example, fumed (or pyrogenic) silica, precipitated silica, or silica aerogel, with silica aerogel being particularly preferred. The term “aerogel” refers to a substantially amorphous organic or inorganic gel with air in the pores. Most preferably, the aerogel comprises silica and is prepared by modifying the surface of a hydrogel with a silylating agent and drying the surface-modified gel. The silica aerogel produced by this process may be partially or completely hydrophobic depending on the degree and type of silylation. The silica aerogels disclosed in WO 98/23366 are especially desirable as the metal oxide in the surface coating composition of the present invention.
The treated metal oxide has a hydrophobic character. Any suitable hydrophobic moiety may be bonded to the metal oxide of the present invention to obtain the effect. Suitable hydrophobic moieties are derived, for example, from compounds of the following general formulae:
R
3
Si-O-SiR
3
(I)
R
3
Si-N(H)-SiR
3
(II)
Wherein the radicals R are identical or different and are each hydrogen or a nonreactive, organic, linear, branched, cyclic, saturated or unsaturated, aromatic or heteroaromatic radical, preferably C
1
-C
18
alkyl or C
6
-C
14
aryl, more preferably C
1
-C
6
alkyl, cycloalkyl, phenyl, vinyl, or acryl. Equally suitable hydrophobic moieties can be derived from silanes of the formulae R
1
4-n
SiCl
n
or R
1
4-n
Si(OR
2
)
r
, where n=1-4, and R
1
and R
2
are identical or different and are each hydrogen or a nonreactive, organic, linear, branched, cyclic, saturated or unsaturated, aromatic or heteroaromatic radical, preferably a C
1
-C
18
alkyl or C
6
-C
14
aryl, and more preferably a C
1
-C
6
alkyl, cyclohexyl, or phenyl. The radicals may also contain halogen substituents, such as fluorine or chlorine. Most preferably, the hydrophobic moiety is a trimethyl silyl, a vinyl dimethyl silyl, a acryl dimethyl silyl, or a dimethyl dicholor silyl.
The metal oxide preferably is characterized by a degree of hydrophobicity of at least about 40% v/v. The degree of hydrophobicity desirably is as high as possible inasmuch as a higher degree of hydrophobicity generally provides improved water resistance.
The term “degree of hydrophobicity” refers to the ratio by volume of methanol in a water-methanol mixture that wets the silica aerogel, thereby forming a homogeneous suspension.
The metal oxide can be in the form of discrete individual particles, which can be in aggregated or non-aggregated form. The metal oxide particles can have any suitable diameter. Generally, the metal oxide has a median particle diameter of about 1-15 &mgr;m (e.g., 2-15 &mgr;m), preferably 2-10 &mgr;m. The particle
Brunsman David
Cabot Corporation
Cheatham Tim A.
LandOfFree
Surface coating composition does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Surface coating composition, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Surface coating composition will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2944926