Substituted napthopyrans

Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...

Reexamination Certificate

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C252S586000, C524S110000, C351S163000, C359S241000, C428S500000

Reexamination Certificate

active

06340766

ABSTRACT:

DESCRIPTION OF THE INVENTION
The present invention relates to substituted 2H-naphtho[1,2-b]pyran compounds and to compositions and articles containing such naphthopyran compounds. When exposed to light radiation involving ultraviolet rays, such as the ultraviolet radiation in sunlight or the light of a mercury lamp, many photochromic compounds exhibit a reversible change in color. When the ultraviolet radiation is discontinued, such a photochromic compound will return to its original color or colorless state.
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. U.S. Pat. No. 3,567,605 (Becker) describes a series of pyran derivatives, including certain benzopyrans and naphthopyrans. These compounds are described as derivatives of chromene and are reported to undergo a color change, e.g., from colorless to yellow-orange, on irradiation by ultraviolet light at temperatures below about −30° C. Irradiation of the compounds with visible light or upon raising the temperature to above about 0° C. is reported to reverse the coloration to a colorless state.
U.S. Pat. No. 5,066,818 describes various 3,3-diaryl-3H-naphtho[2,1-b]pyrans as having desirable photochromic properties, i.e., high colorability and acceptable fade, for ophthalmic and other applications. Also disclosed by way of comparative example in the '818 patent are the isomeric 2,2-diaryl-2H-naphtho[1,2-b]pyrans, which are reported to require unacceptably long periods of time to fade after activation.
U.S. Pat. No. 3,627,690 describes photochromic 2,2-di-substituted-2H-naphtho[1,2-b]pyran compositions containing minor amounts of either a base or weak-to-moderate strength acid. The addition of either an acid or base to the naphthopyran composition is reported to increase the fade rate of the colored naphthopyrans, thereby making them useful in eye protection applications such as sunglasses. It is reported therein further that the fade rate of 2H-naphtho-[1,2-b]pyrans without the aforementioned additives ranges from several hours to many days to reach complete reversion.
U.S. Pat. Nos. 5,458,814, 5,573,712, 5,650,098, 5,656,206 and 5,658,500 disclose 2H-naphtho[1,2-b]pyrans substituted in the 5- and 6-positions that possess a reasonable rate of fade as well as high colorability. The compounds exhibit activated colors ranging from yellow to red/purple. International Patent Application Publication No. WO 98/04937 describes 2H-naphtho[1,2-b]pyrans having alkoxy groups as substituents at the 7- or 9-positions of the naphthopyran ring.
Photochromic compounds may be incorporated into plastic substrates, such as ophthalmic lenses, by various methods described in the art. Such methods include dissolving or dispersing the compound within the surface of a substrate, e.g., imbibition of the photochromic compound into the substrate by immersion of the substrate in a hot solution of the photochromic compound or by depositing the photochromic compound on the surface of the substrate and thermally transferring the photochromic compound from a carrier into the substrate. The term “imbibition” or “imbibe” is intended to mean and include permeation of the photochromic compound into the substrate, solvent assisted transfer absorption of the photochromic compound into the substrate, vapor phase transfer and other such transfer mechanisms.
The extent to which the photochromic compounds penetrate the polymeric substrate generally increases with increasing temperature, increasing concentration of photochromic compounds at the surface of the polymeric substrate and increasing period of contact with the polymeric substrate. The ease with which the photochromic compounds are incorporated is also dependent upon the characteristics of the photochromic compounds and of the polymeric substrate. The molecular size, melting point, and carrier matrix solubility of the photochromic compounds as well as the receptivity of the polymeric substrate all affect the ease of incorporation of the photochromic compounds.
In some cases, due to the numerous variables affecting production of photochromic articles, photochromic compounds may not be incorporated into the plastic substrate with sufficient uniformity and to a sufficient depth. This can result in poor performance of the photochromic compound, e.g., inadequate reversible color change of the photochromic article and non-neutral color formation. Depending on the solubility of the photochromic compound in the inbibition composition, crystals may form and cause cosmetic defects on the surface of the photochromic article.
Methods for incorporating photochromic compounds into polymeric substrates have been disclosed in U.S. Pat. Nos. 4,286,957, 4,880,667, 5,789,015 and 5,975,696. Various photochromic compositions used in the process of incorporating photochromic compounds into polymeric substrates have been disclosed in U.S. Pat. Nos. 5,185,390, 5,391,327 and 5,770,115. As disclosed in U.S. Pat. No. 5,753,146, in order to achieve activated neutral colors, it is necessary to select and combine photochromic naphthopyran compounds on the basis of their lambda max value, sensitivity, optical density and fade rate under solar simulated conditions.
It has been unexpectedly discovered that 2H-naphtho[1,2-b]pyran compounds having a cycloalkyl ester-substituent in the 5-position are more soluble in polymeric matrices used in imbibition processes than 2H-naphtho[1,2-b]pyrans having similar photochromic properties that are substituted with a non-cycloalkyl ester. The cycloalkyl ester-substituted 2H-naphtho[1,2-b]pyran compounds may be used individually or in combination with other complementary photochromic compounds to produce photochromic articles. When used in place of non-cycloalkyl ester-substituted 2H-naphtho[1,2-b]pyran compounds in imbibition processes with polymeric carriers, e.g., hydroxypropyl cellulose, use of the compounds of the present invention enables the successful preparation of photochromic imbibed lenses of neutral activated colors having a reduced occurrence of cosmetic defects.
DETAILED DESCRIPTION OF THE INVENTION
In recent years, photochromic plastic materials, particularly 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 and airplanes, have been of interest because of the potential safety features that such transparencies offer.
In accordance with the present invention, it has now been discovered that 2H-naphtho[1,2-b]pyrans having a cycloalkyl ester substituent at the 5-position may be prepared. These naphthopyran compounds demonstrate improved solubility in polymeric matrices used as carriers in imbibition processes. Use of the compounds of the present invention in place of non-cycloalkyl ester-substituted 2H-naphtho[1,2-b]pyrans in imbibition processes makes possible the preparation of photochromic articles of neutral color having a reduced occurrence of cosmetic defects.
The types of cosmetic defects that can occur on the polymer surface during the imbibition process from the use of a photochromic compound that is not compatible, e.g., soluble, in the imbibition composition include pits, dimples, spots, orange peel, uneven patterns and distortions of reflected light. The terms used to describe these cosmetic defects are also used to describe defects in coatings. Definitions of these and other such surface defect terms are found in the
Paint/Coating Dictionary
by the Federation of Societies for Coating Technology, Philadelphia.
In one contemplated embodiment, photochromic articles prepared by the imbibition of photochromic compounds of the present invention into polymeric organic substr

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