Compositions: coating or plastic – Coating or plastic compositions – Silicon containing other than solely as silicon dioxide or...
Reexamination Certificate
2000-04-20
2002-01-29
Dawson, Robert (Department: 1712)
Compositions: coating or plastic
Coating or plastic compositions
Silicon containing other than solely as silicon dioxide or...
C106S287140, C524S588000, C524S783000, C524S785000, C524S789000, C524S837000, C528S026000, C528S034000
Reexamination Certificate
active
06342097
ABSTRACT:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to coating compositions as well as methods of making and using same, and more particularly but not by way of limitation, to coating compositions which, when cured, provide substantially transparent coatings having abrasion resistance, a matched refractive index to that of the substrate, and which can be tailored to control the extent of tint absorption.
The present invention also relates to liquid coating compositions as well as methods of making and using same having improved abrasion resistance and improved stability wherein the liquid coating compositions are derived from aqueous-organic solvent mixtures containing effective amounts of an epoxy-functional silane, a carboxylic acid component, a colloidal metal oxide component, and a disilane.
2. Description of Prior Art
Silica based coatings deposited on plastic materials are useful for their abrasion resistance and weatherability and thus extend the useable life of the plastic material. These coatings, in most cases, do not match the refractive index of the plastic material and allow for interference patterns to arise due to the refractive index mismatch between the cured coating film and the plastic substrate material. This mismatch leads to increased reflectivity of the coated plastic material and to exacerbation of material flaws due to the increased reflectivity.
BRIEF SUMMARY OF THE INVENTION
The present invention provides compositions and methods of using and making said compositions, having improved stability which, when applied to a variety of substrates and cured, form transparent coatings which have abrasion resistant properties, a matched refractive index to that of the substrate, and which can be tailored to control the extent of tint absorption.
Broadly, the coating compositions of the present invention comprise an aqueous-organic solvent mixture containing from about 10 to about 90 weight percent, based on the total solids of the composition, of a mixture of hydrolysis products and partial condensates of an epoxy-functional silane, from about 1 to about 90 weight percent, based on the total weight of the composition, of a carboxylic acid functional compound selected from the group consisting of carboxylic acids, multifunctional carboxylic acids, anhydrides, and combinations thereof, from about 1 to 90 weight percent, based on the total solids of the composition, of a metal oxide composite colloid, and from about 1 to 75 weight percent, based on the total solids of the composition, of a disilane.
The coating compositions of the present invention may further include from about 0.1 to about 50 weight percent, based on the total solids of the composition of a mixture of hydrolysis products and partial condensates of one or more silane additives, from about 0.1 to 75 weight percent, based on the total solids of the composition, of a colloidal silica material, from about 0.1 to 75 weight percent, based on the total solids of the composition, of a tetrafunctional silane.
It is an object of the present invention to provide coating compositions and methods of making and using said compositions having improved stability, which form transparent coatings upon curing. It is a further object of the present invention to provide stable coating compositions, which form transparent coatings upon curing and which also have improved adhesion properties, improved resistance to crack formation, and a matched refractive index to that of the substrate.
Other objects, advantages and features of the present invention will become apparent upon reading the following detailed description in conjunction with the appended claims.
DETAILED DESCRIPTION OF THE INVENTION
Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description. The invention is capable of other embodiments or of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting.
The present invention relates to coating compositions having improved stability which, when applied to a variety of substrates and cured, form substantially transparent coatings which possess improved adhesion, improved resistance to crack formation and have a matched refractive index to that of the substrate.
For measuring the refractive indexes of the cured coating compositions, each composition was applied to a cleanly etched lead-silicate glass plaque by dip coating at 2 inches per minute and curing for a period of 1 hour at 120° C. The refractive indexes were measured using a Bausch and Lomb Abbe-3L refractometer. Either diiodomethane or 1-bromonaphthalene was used as the contact liquid. The standard procedures for measurement and instrument maintenance contained in the operator's manual for the Bausch and Lomb Abbe-3L refractometer were used for data gathering and processing. For testing coated samples, coating compositions were applied to ADC lenses and cured at a temperature of from 95° C. to 120° C. for a period of 3 hours. Semi-quantitative assessments of the extent of cracking and adhesion were made using the following tests.
For testing adhesion of the coated articles the procedures of ASTM D-3359, i.e. the tape test, were followed.
A typical test for cracking, and adhesion consists of immersion of the coated article in boiling water or boiling tap water tint for a period of time, e. g. 1 hour, followed by inspection for crack formation and testing for adhesion. Specifically, lenses were tested in BPI Black Tint (Brain Power, Inc.) under boiling conditions. In this test a bottle of BPI tint (approximately 100 grams) was diluted to about 900 grams with tap water and brought to a boil. The coated article was immersed in the boiling solution for a period of 30 minutes. The coated article was removed from the tint solution and inspected for cracking and tested for adhesion.
For measuring the control of tint absorption, a typical test consists of exposing the coated article to the tint mixture above which is in either deionized or tap water for a period of fifteen minutes at a temperature in the range between 90° C. and 100° C. The light transmittance is measured, using a Gardner XL-835 Colorimeter, in 15 minute intervals.
For testing abrasion resistance of coated substrates, any of a number of quantitative test methods may be employed, including the Taber Test (ASTM D-4060), the Tumble Test and Standard Method for the Modified Bayer Test, which is described in The AR Council of America Standard Testing Procedures section 5.2.5 and is a variation of the test method, ASTM F735-81. In addition, there are a number of qualitative test methods that may be used for measuring abrasion resistance, including the Steel Wool Test and the Eraser Test. In the Steel Wool Test and the Eraser Test, coated substrate samples are scratched under reproducible conditions (constant load, frequency, etc.). The scratched test samples are then compared and rated against standard samples. A semi-quantitative application of these test methods involves the use of an instrument, such as a Spectrophotometer or a Colorimeter, for measuring the scratches on the coated substrate as a haze gain.
The measured abrasion resistance of a cured coating on a substrate, whether measured by the Modified Bayer Test, Taber Test, Steel Wool Test, Eraser Test, Tumble Test, etc. is a function, in part, of the cure temperature and cure time. In general, higher temperatures and longer cure times result in higher measured abrasion resistance. Normally, the cure temperature and cure time are selected for compatibility with the substrate; although, sometimes less than optimum cure temperatures and cure times are used due to process and/or equipment limita
Lembo Bryan S.
Terry Karl W.
Dawson Robert
Dunlap Codding & Rogers P.C.
SDC Coatings Inc.
Zimmer Marc S.
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