Stock material or miscellaneous articles – Composite – Of polyamidoester
Reexamination Certificate
2002-08-30
2004-05-11
Nakarani, D. S. (Department: 1773)
Stock material or miscellaneous articles
Composite
Of polyamidoester
C428S413000, C428S423100, C428S424400, C428S425300, C428S425500
Reexamination Certificate
active
06733887
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to photochromic polymerizates. More particularly, this invention relates to poly(urea-urethane) articles to which at least a partial coating of a photochromic polymeric coating has been applied.
Photochromic compounds exhibit a reversible change in color when exposed to light radiation involving ultraviolet rays, such as the ultraviolet radiation in sunlight or the light of a mercury lamp. Various classes of photochromic compounds have been synthesized and suggested for use in applications in which a sunlight-induced reversible color change or darkening is desired. The most widely described classes of photochromic compounds are oxazines, pyrans and fulgides.
The general mechanism responsible for the reversible change in color, i.e., a change in the absorption spectrum in the visible range of light (400-700 nm), exhibited by different types of photochromic compounds has been described and categorized. See John C. Crano, “Chromogenic Materials (Photochromic)”,
Kirk-Othmer Encyclopedia of Chemical Technology,
Fourth Edition, 1993, pp. 321-332. The general mechanism for the most common classes of photochromic compounds, e.g., indolino spiropyrans and indolino spirooxazines, involves an electrocyclic mechanism. When exposed to activating radiation, these compounds transform from a colorless closed ring compound into a colored open ring species. In contrast, the colored form of fulgide photochromic compounds is produced by an electrocyclic mechanism involving the transformation of a colorless open ring form into a colored closed ring form.
In the aforedescribed electrocyclic mechanisms, the photochromic compounds require an environment in which they can reversibly transform. In solid polymer matrices, the rates at which the photochromic processes of activation, i.e., formation of color or darkening, and fading, i.e., the return to the original or colorless state, occur are believed to be dependent on the free volume in the polymer matrix. The free volume of the polymer matrix is dependent upon the flexibility of the chain segments of the polymer environment surrounding the photochromic compound, i.e., the local mobility or local viscosity of the chain segments comprising the matrix. See Claus D. Eisenbach, “New Aspects of Photochromism in Bulk Polymers”, Photographic Science and Engineering, 1979, pp. 183-190. One of the main obstacles reported by Claus D. Eisenbach, for the larger commercial application of photochromic systems, is the slow rate of photochromic activation and fade in a solid polymer matrix.
In recent years, photochromic articles, particularly photochromic plastic materials for optical applications, have been the subject of considerable attention. In particular, photochromic ophthalmic plastic lenses have been investigated because of the weight advantage they offer, vis-á-vis, glass lenses. Moreover, photochromic transparencies for vehicles, such as cars, boats and airplanes, have been of interest because of the potential safety features, that such transparencies offer.
Polymers that are typically used to prepare impact resistant articles include thermoplastic polycarbonate, e.g., a resin derived from bisphenol A and phosgene, and acrylic polymers. Polycarbonates are considered superior to acrylics in impact resistance but have limited wearability since resistance to abrasion and chemicals is poor. The performance of photochromic compounds in such polycarbonates is also poor because the polycarbonate does not have sufficient internal free volume for photochromic compounds to function properly, i.e., to achieve an acceptable activated intensity and acceptable rates of activation and fade.
Photochromic plastic articles can be prepared without the need to incorporate the photochromic compound(s) into the plastic substrate. This is accomplished by applying photochromic polymeric coatings on the plastic substrate.
Although the use of photochromic compounds in polymeric coatings has been described in the literature, the use of photochromic compounds in polymeric coatings applied to substrates of poly(urea-urethane) resins having free isocyanate groups to produce articles has not been disclosed.
DETAILED DESCRIPTION OF THE INVENTION
The article of the present invention can exhibit one or more of the following properties: impact resistance, photochromic properties and good adhesion of coating to substrate without the use of an intermediate layer, coating or surface treatment to improve the adhesion of the applied coating.
Impact resistant ophthalmic substrates are defined herein as materials used to produce lenses that demonstrate a rating at least 20 times more impact resistant than the minimal level which is 0.15, specified by the Food and Drug Administration (FDA) in CFR 801.410. The increase in impact resistance of at least 20 fold is based on the impact energy of the lens divided by the minimal impact energy specified by the FDA. For example, an impact resistant lens would have an impact energy greater than 3.0 since 3.0/0.15 equals 20.
In one non-limiting embodiment, the substrate for the photochromic coatings is an non-elastomeric poly (urea-urethane) polymerizate comprising free isocyanate groups. By the term “non-elastomeric” is meant that an article of the present invention has an ultimate elongation at break of less than 200 percent. In comparison, the term “elastomer”, according to
Hawley's Condensed Chemical Dictionary,
11
th
Edition, refers to synthetic thermosetting high polymers having properties similar to those of vulcanized natural rubber, namely the ability to be stretched to at least twice their original length and to retract very rapidly to approximately their original length when released.
It is noted that, as used in this specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless expressly and unequivocally limited to one referent.
For the purposes of this specification, unless otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.
Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.
The phrase “at least a partial coating” means an amount of coating covering from a portion to the complete surface of the substrate. The phrase “an at least partially abrasion resistant coating” refers to a coating that demonstrates a Bayer Abrasion Resistance Index of from at least 1.3 to 10.0 in ASTM F-735 Standard Test Method for Abrasion Resistance of Transparent Plastics and Coatings Using the Oscillating Sand Method. The phrase “an at least partially antireflective surface” is a surface that has been treated to at least partially improve the antireflective nature of that surface by increasing the percent transmittance as compared to an untreated surface. The improvement in percent transmittance can range from 1 to 9 percent above the untreated surface. Put another way, the percent transmittance of the treated surface can range from a percentage greater than the untreated surface up to 99.9.
The phrase “demonstrating substantially no loss of adh
Okoroafor Michael O.
Smith Robert A.
Mallak Frank P.
Nakarani D. S.
PPG Industries Ohio Inc.
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