Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2000-11-28
2002-08-13
Sellers, Robert E. L. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C252S586000, C523S457000, C523S461000, C524S104000, C524S110000, C524S112000, C524S091000, C524S096000
Reexamination Certificate
active
06433043
ABSTRACT:
The present invention relates to photochromic compositions of enhanced kinetic performance and to a method for improving the performance of organic photochromic compounds in polymeric substrates. More particularly, this invention relates to improved photochromic compositions comprising organic photochromic compound(s), and optionally carrier, stabilizer and/or conventional additives wherein the improvement comprises including at least one kinetic enhancing additive. The kinetic enhancing additive is used in an amount sufficient to improve the performance of organic photochromic compounds in polymeric organic host materials, e.g., polymerizates and polymeric coatings. Still more particularly, this invention relates to photochromic articles, e.g., ophthalmic lenses, made of polymeric substrates having incorporated therein organic photochromic compounds and kinetic enhancing additives such as epoxy-containing compound(s), plasticizer(s) and/or organic polyols.
Photochromic compounds exhibit a reversible change in color when exposed to radiation including 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 are oxazines, chromenes and fulgides.
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 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 solvent solubility of the photochromic compounds as well as the receptivity of the polymeric substrate all affect the ease of incorporation of the photochromic compounds. Due to the numerous variables affecting production of photochromic articles, in some cases, 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 and inadequate reversible color change 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. The use or avoidance of plasticizers in such methods is mentioned in U.S. Pat. Nos. 4,880,667 and 5,789,015. In U.S. Pat. No. 4,880,667 at column 5, line 53-58,it is stated that plasticizers may be added to the monomeric materials used to form the polymeric host to improve the diffusion of the photochromic compounds into the subsurface. In U.S. Pat. No. 5,789,015 at column 7 line 66 to column 8 line 2, an inert liquid, i.e., a liquid which does not plasticize the surface of the lens, is used to form suspensions of two photochromic additives to be impregnated into the plastic substrate. 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.
The aforementioned photochromic compositions and methods of incorporating photochromic compounds into polymeric substrates are generally known in the art and can be used in the process of the present invention.
The use of epoxy-containing compounds with photochromic compounds has been disclosed in U.S. Pat. Nos. 5,395,566, 5,462,698, 5,621,017 and 5,776,376. U.S. Pat. No. 5,395,566 discloses a photochromic composition of a compound having at least one radical polymerizable group and at least one epoxy group and a photochromic compound. U.S. Pat. No. 5,462,698 discloses a photochromic composition of a compound having at least one epoxy group, a fulgide compound and two different (meth)acrylic monomers. U.S. Pat. No. 5,621,017 discloses a photochromic composition of a radical polymerization monomer, photochromic compound and photopolymerization initiator. U.S. Pat. No. 5,776,376 discloses a photochromic composition of a polymerizable monomer composed of a compound having at least one epoxy group, various monomers, an a-methylstyrene dimer and photochromic compounds.
In each of the aforedescribed patents disclosing compositions containing epoxy-containing compounds and photochromic compounds, the compositions contained radically polymerizable components and were polymerized to make photochromic lenses.
Although methods exist for incorporating photochromic compounds into polymeric substrates, improvements in such methods are sought. It has now been discovered that the use of kinetic enhancing additive in a photochromic composition comprising organic photochromic compound(s) and optionally carrier, light stabilizer(s), ultraviolet light absorber(s), antioxidant(s), rheology control agents(s) and/or leveling agent(s), improves the performance of the photochromic compound as demonstrated by an increased rating in the Photochromic Performance Test. The ratings of the test are defined as the result obtained when the change in optical density (&Dgr;OD) at 15 minutes is divided by the Bleach (T 1/2) and then multiplied by 10,000. Photochromic articles may be produced by transfer processes incorporating the improved photochromic composition of the present invention into a polymeric substrate.
DETAILED DESCRIPTION OF THE INVENTION
In accordance with the present invention, a kinetic enhancing additive is defined herein as a material which when added to a photochromic imbibition composition, results in an increased rating in the Photochromic Performance Test described in Example 29. A photochromic performance improving amount of the kinetic enhancing additive is defined herein as the amount necessary to use in the photochromic imbibition composition to result in an increased rating in the Photochromic Performance Test as compared to a photochromic imbibition composition substantially free of the kinetic enhancing additive. Materials which are kinetic enhancing additives include, but are not limited to, epoxy-containing compound(s), plasticizer(s), organic polyols and mixtures thereof.
Other than in the operating examples, or where otherwise indicated, all numbers expressing quantities of ingredients or reaction conditions used herein are to be understood as modified in all instances by the term “about”.
The disclosures of the patents and articles cited herein related to photochromic compounds, plasticizers, lactone polyesters, stabilizers, poly(urea-urethanes), polymeric organic host materials, photochromic compositions, i.e., photochromic imbibition compositions, methods of incorporating photochromic compounds into a polymeric substrate and methods for producing hard or soft contact lenses are incorporated herein, in toto, by reference.
In each instance where the term “weight percent” is used herein with respect to the photochromic composition, it is to be understood that the described weight percent is based on the total weight of the photochromic composition.
Epoxy-containing compounds that may be use
Kumar Anil
Misura Michael S.
Mallak Frank P.
Sellers Robert E. L.
Transitions Optical Inc.
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