Compositions – Light transmission modifying compositions – Displaying color change
Reexamination Certificate
2001-01-19
2003-03-11
Tucker, Philip (Department: 1712)
Compositions
Light transmission modifying compositions
Displaying color change
C528S061000, C528S062000, C528S064000, C428S423100, C428S423300, C428S423500, C428S424200, C351S163000
Reexamination Certificate
active
06531076
ABSTRACT:
DESCRIPTION OF THE INVENTION
The present invention relates to photochromic organic resin compositions and the impact resistant polymerizates and coating compositions made therefrom. More particularly, this invention relates to poly(urea-urethane) compositions comprising the reaction product of at least one polyol, e.g., diol, at least one polyisocyanate and at least one polyamine curing agent, which compositions contain a photochromic amount of organic photochromic compound(s). The present invention also relates to photochromic polymerizates and articles having photochromic coatings prepared from such organic resin compositions.
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.
The use of photochromic compounds in polyurethanes has been disclosed in WO 98/37115; German Democratic Republic Patent No. 116 520; European Patent Applications 0 146 136 and 0 927 730; U.S. Pat. No. 4,889,413; and Japanese Patent Applications 3-269507 and 5-28753. Although the use of photochromic compounds in polyurethanes has been described in the literature, the use of photochromic compounds in poly(urea-urethane) resins and coatings and in impact resistant articles and coated articles made from such resins and coatings has not been disclosed.
It has now been discovered that an impact resistant photochromic-article can be produced from a composition comprising the reaction product of (a) at least one polyol having greater than 1.0 hydroxyl groups per molecule, e.g., diol; (b) at least one polyisocyanate having greater than 1.0 isocyanato groups per molecule; (c) at least one polyamine having greater than 1.0 amino groups per molecule, and optionally (d) at least one polyol having greater than 2.0 hydroxyl groups per molecule. In a preferred embodiment, the number of isocyanato groups of the polyisocyanate reactants is greater than the number of hydroxyl groups of the polyol reactants. Organic photochromic compounds can be added to the resin composition prior to forming a coating or polymerizate, e.g., a lens, or the photochromic compounds can be imbibed or transferred into the coating or polymerizate.
DETAILED DESCRIPTION OF THE INVENTION
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-a-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 polymers based on bisphenol-A-polycarbonates and acrylic polymers. Thermoplastic 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.
Other than in the operating examples, or where otherwise indicated, all numbers expressing wavelengths, quantities of ingredients or reaction conditions used herein are to be understood as modified in all instances by the term “about”. The number of hydroxyl, isocyanato and/or amino groups per molecule reported herein is an average value and can be a partial number, e.g., 1.8.
The disclosures of the patents and articles cited herein related to poly(urea-urethane), diols and their reaction with &egr;-caprolactone, polyols, catalysts, photochromic compounds, imbibition compositions and stabilizers are incorporated herein, in toto, by reference.
It has now been discovered that impact resistant photochromic polymers having acceptable photochromic properties can be prepared. In accordance with the present invention impact-resistant non-elastomeric photochromic poly(urea-urethane) polymerizates are prepared. By the term “non-elastomeric” is meant that an article of the present invention could not be stretched to twice its length and upon release resume its original length. The term polymerizate is defined herein to include polymeric coatings and films and articles such as lenses prepared from the organic resin composition of the present invention.
The polymerizates of the present invention are made photochromic either by the addition of organic photochromic compounds to the reactants used to form the polymerizate or by methods that imbibe or transfer the photochromic compounds into the polymerizate. In particular, the poly(urea-urethane) comprises the reaction product of reactants comprising (a) at least one polyol having greater than 1.0 hydroxyl groups per molecule, e.g., 1.1 hydroxyl groups; (b) at least one polyisocyanate having greater than 1.0 isocyanato groups per molecule; (c) at least one polyamine having greater than 1.0 amino groups per molecule, each amino group being independently selected from primary amino and secondary amino; and optionally, (d) at least one polyol having greater than 2.0 hydroxyl groups per molecule; provided that the number of isocyanato groups of the isocyanate reactants is greater than the number of hydroxyl groups of the polyol reactants.
One polyol, e.g., diol, or more than one diol may be employed in forming the poly(urea-urethane). The polyols which can be used are numerous and widely varied. They are preferably substantially free from ethylenic or acetylenic unsaturation. The polyols which are used are most often aliphatic, alicyclic, aromatic, aliphatic-alicyclic, aliphatic-aromatic, alicyclic-a
Crano John C.
Knox Carol L.
Okoroafor Michael O.
Smith Robert A.
Tabakovic Rifat
Mallak Frank P.
PPG Industries Ohio Inc.
Tucker Philip
LandOfFree
Photochromic organic resin 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 Photochromic organic resin composition, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Photochromic organic resin composition will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3078368