Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Patent
1986-09-25
1989-05-09
Michl, Paul R.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
526246, 526279, 523107, C08F21418, G03B 2146
Patent
active
048291374
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention is directed to eye-compatible lenses, particularly hard contact lenses having excellent oxygen permeability and wettability.
Contact lenses presently on the market are classified into two large groups: soft contact lenses and hard contact lenses. Hard contact lenses are better able than soft contact lenses to retain visual characteristics, but are less comfortable. The art has sought to increase oxygen permeability of hard contact lenses, to extend the length of time they can be worn without causing corneal damage or discomfort.
One proposed solution has been the formation of a copolymer of methyl methacrylate and a siloxane methacrylate compound. This solution has been less than satisfactory, since the lenses offered are not as hard, rigid, nor wettable as lenses formed from polymethyl methacrylate. In addition, such lenses are fragile and have poor mechanical processability.
The object of the present invention is to overcome the deficiencies in the state of the art by offering lenses having a high degree of oxygen permeability, excellent wettability, and, if desired, ultraviolet absorption. The primary benefit of UV absorptivity is the resistance to user development of cataracts.
SUMMARY OF THE INVENTION
The present invention is directed to eye-compatible, continuously-wearable, oxygen-permeable optical lenses of excellent wettability, formed of copolymers of at least one organosilicon monomer with at least one hexafluoroisopropyl ester of an unsaturated carboxylic acid containing from 2 to about 10 carbon atoms and 1 or 2 carboxyl groups, at least one hydrophilic monomer, and at least one crosslinking monomer. The preferred hexafluoroisopropyl ester of an unsaturated carboxylic acid is hexafluoroisopropylmethacrylate. The organosilicon monomer is preferably a monomer system comprising an organosilane or an organosiloxane of the general formula: ##STR1## wherein R.sub.1 is hydrogen or methyl, a is 0 or 1, b is from 1 to about 4, and X is an organosilicon moiety containing up to about 16 silicon atoms. It is preferred that at least a portion, and as much as 100 percent, of the organosilicon monomer system is a hydroxyorganosilicon monomer which is a monomer having at least one hydroxyl group bonded to silicon. Preferably from 0.1 to about 10 percent by weight of the monomers is a hydroxyorganosilicon monomer. The presently preferred monomers are tris(trimethylsiloxy)-.gamma.-methacryloxypropylsilane, hydroxy-di(trimethylsiloxy)silylpropylmethacrylate, and 1,3,-bis(-methacryloxypropyl)-1,1,3,3-tetra(-trimethylsiloxy)disiloxane, particularly mixtures thereof.
A second component is a fluoroorgano monomer system comprising at least one hexafluoroisopropyl ester of an unsaturated carboxylic acid containing from 1 to about 10 carbon atoms and 1 or 2 carboxyl groups. These monomers, as against monomers of close structure, such as hexafluorobutylmethacrylate, have been surprisingly and unexpectedly found to enable the formation of lenses of extremely high oxygen permeability. The use of hexafluoroisopropylmethacrylate, for instance, enables achievement of an oxygen permeability in excess of Dk 150, and even in excess of 300. Lenses formed can be worn continuously.
A final component is a crosslinking monomer which is a crosslinking agent, preferably an organosilicon monomer, present in an amount up to about 5, preferably up to about 2, percent by weight based on the total weight of the monomers.
At least one hydrophilic monomer is included, preferably an unsaturated carboxylic acid capable of inducing wettability, and is present in an amount sufficient to provide in the resultant polymer a receding contact angle of about 45.degree. or less. Methacrylic acid is preferred.
A UV-absorbing agent, if desired, may be included. In this instance, the agent may be a copolymerizable UV-absorbing monomer, preferably a hydroxybenzophenone or a benzotriazole compound of the formula: ##STR2## wherein R.sub.1, a and b are as defined above, d is 1 or 2, and Z is: ##STR3## wher
REFERENCES:
patent: 4390676 (1983-06-01), Loshaek
patent: 4419505 (1983-12-01), Ratkowski et al.
patent: 4433125 (1984-02-01), Ichinolte et al.
patent: 4535138 (1985-08-01), Ratkowski et al.
patent: 4540761 (1985-09-01), Kawamura
Bausch & Lomb Incorporated
Doody Patrick A.
Michl Paul R.
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