Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Patent
1999-03-31
2000-11-28
Seidleck, James J.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Compositions to be polymerized by wave energy wherein said...
522182, 522180, 526308, 526286, 526282, 5262923, 526328, 5263285, 5263231, 5263232, 526306, 528306, 528307, 528308, 428413, 428419, 4284228, 428500, C08F 246, C08F21612, C08F11612, C08G 6352
Patent
active
061536636
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to the manufacture of plastic optical articles such as video discs and ophthalmic lenses.
The most widely used plastic ophthalmic lens material is polymerised diethylene glycol bis (allyl carbonate). This polymer has provided a satisfactory material for the manufacture of ophthalmic lenses because of a combination of features, including excellent transmission, resistance to discolouration, high strength and high impact resistance. The material has a reasonable abrasion resistance and can be coated to improve that resistance.
Lenses formed from polymers including divinyl benzene are generally brittle and have a high yellowness index.
In Australian Patent Application 81216/87, the entire disclosure of which is incorporated herein by reference, applicant describes a cross-linkable casting composition including at last polyoxyalkylene glycol diacrylate or dimethyacrylate and at least one poly functional unsaturated cross-linking agent. Whilst the lenses produced from the prior art compositions provide advances in the art, difficulties may be encountered in certain applications. For example, difficulties may be encountered in some patients in fitting lenses made from such compositions. Eye discomfort, including eye fatigue problems, may be encountered. Moreover, such lenses have been found to be cosmetically unattractive.
Further, in Australian Patent Application 75160/91, the entire disclosure of which is incorporated herein by reference, applicant describes a polyoxyalkylene glycol diacrylate or dimethacrylate; a monomer including a recurring unit derived from at least one radical-polymerisable bisphenol monomer capable of forming a homopolymer having a high refractive index of more than 1.55; and a urethane monomer having 2 to 6 terminal groups selected from a group comprising acrylic and methacrylic groups.
Japanese Patent Application 63-309509 to Showa Denko KK discloses the formation of a prepolymer of divinyl benzene and a polythiol compound which may be used in the formation of optical materials with high refractive indexes.
Japanese Patent Application 63-19498 to Mitsubishi Gas discloses a high refractive index composition of divinyl benzene and a thiol compound. However optical lenses produced thereby exhibit unacceptable strain characteristics and core times.
However, there remains a need in the prior art for optical articles of very high refractive indexes, very low densities and excellent colour, that still retain excellent mechanical properties.
Accordingly, it is an object of the present invention to overcome, or at least alleviate, one or more of the difficulties related to the prior art.
Accordingly, the present invention provides a cross-linkable polymeric casting composition including an effective amount of
a divinyl ester monomer of a bicyclic or polycyclic compound; and optionally a minor amount of
a di- or polythio compound.
The inclusion of the bicyclic monomer may provide an increase in rigidity, (and thus hardness) and glass transition temperature (Tg). The cross-linkable polymeric casting composition is U.V. curable. This may provide a significant decrease in cure time, e.g. from approximately 6 hours to approximately 1 hour.
The optical article formed from the casting composition of the present invention may exhibit a refractive index in the high to very high refractive index range.
The divinyl ester cyclic monomer may be a divinyl ester of an alkoxylated bisphenol C or bisphenol S, or mixtures thereof.
The bicyclic or polycyclic monomer may be selected from compounds having the formula ##STR1## wherein
G is selected from the group consisting of ##STR2## wherein M is selected from the group consisting of a bond, ##STR3## --S-- methylene and --CH.sub.2 --S--CH.sub.2 --
R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are independently selected from the group consisting of hydrogen and alkyl of 1 to 6 carbon atoms,
n is an integer having a value of 0 to 10,
Y is hydrogen or a halogen, preferably fluorine, chlorine or bromine, and
J is a unsaturated terminal group part
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Derwent Abstract Accession No. 93-055221/07, JP0500501 1-A, "resin compsn. for moulding glass lens having good transparency comprising styrene deriv., ethylene glycol dimethacrylate, diacrylate cpd., epoxy-modified di(meth)acrylate and peroxy ester" Jan. 14, 1993.
Chen Fang
Toh Huan Kiak
McClendon Sanza
Seidleck James J.
Sola International Holding, Ltd.
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