Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2002-02-01
2004-01-13
Pezzuto, Helen L. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S261000, C526S320000, C526S333000
Reexamination Certificate
active
06677420
ABSTRACT:
BACKGROUN OF THE INVENTION
1. Field of the Invention
The present invention relates to the field of compositions of polymerisable monomers which, after polymerisation, give transparent polymer substrates, and to their use for making optical, particularly ophthalmic, lenses.
2. Description of Related Art
Optical lenses for ophthalmic use made from organic polymer materials are known and have been used for many years.
One of the most widely used materials is obtained by polymerisation of compositions containing diethylene glycol diallyl carbonate (subsequently referred to as CAD).
This monomer is commercially available, for example under the trade name CR39®.
An example of a commercial ophthalmic lens in a material of this type is the ORMA® lens.
This material has intrinsically good mechanical properties, in particular impact strength and scratch resistance, as well as good resistance to organic solvents.
This material may also be readily coloured when desired by the customer.
One of the disadvantages of the use of CAD is the fact that the polymerisation of this monomer is essentially performed thermally, with particularly long heat cycles (several hours or even days).
It would thus be desirable to reduce the length of these polymerisation cycles so as, amongst other reasons, to be able to respond to customers as quickly as possible, to limit the length of time that the moulds used for the lens production are in use, and to reduce the manufacturing costs.
In addition, although CAD materials are generally satisfactory, it would also be desirable to produce materials with improved intrinsic properties.
Various types of materials have already been proposed in the prior art.
The patent U.S. Pat. No. 4,138,538 discloses compositions of allyl monomers such as CAD, containing a methacrylic monomer such as a polyethylene glycol di(meth)acrylate.
This methacrylic monomer may be used at a concentration of 20 to 70% by weight of the polymerisable mixture.
The mixture is photopolymerised, preferably at low temperature, then a thermal treatment is performed.
The patent U.S. Pat. No. 4,650,845 discloses monomer compositions comprising from 0 to 100 parts by weight of a first component which is a poly(meth)acrylate urethane monomer, and from 100 to 0 parts by weight of a second component which is a composition containing:
A) from 30 to 60% by weight of a polyacrylate monomer,
B) from 20 to 70% by weight of a modifier of the shrinkage during the polymerisation,
C) from 0 to 30% by weight of a diluent monomer.
The compositions are preferably photopolymerised.
In practice, the compositions disclosed generally lead to highly crosslinked polymers due to the presence of monomers containing multiple functional groups.
The compositions generally contain monomers containing at least 4 (meth)acrylate groups.
The patent U.S. Pat. No. 4,912,185 discloses compositions of polymerisable monomers, for the production of ophthalmic lenses or video discs, comprising at least one polyoxyalkylene glycol acrylate or methacrylate monomer, at least one crosslinking agent containing several unsaturated functions and at least one urethane monomer with 2 to 6 methacrylic end groups.
In practice, the crosslinking agent cited above contains 3 to 4 vinyl, acrylic or methacrylic functional groups.
Such compositions are preferably hardened by mixed UV/thermal polymerisation.
The patent EP-A-453149 discloses compositions containing a polyoxyalkylene glycol di(meth)acrylate monomer; a monomer containing a bisphenol A unit and leading, by homopolymerisation, to a polymer with refractive index greater than 1.55 and a urethane monomer with 2 to 6 (meth)acrylic end groups.
The polymerisation is preferably mixed UV/thermal.
The U.S. Pat. No. 5,183,870 discloses compositions comprising from 10 to 60% by weight of a polybutylene glycol di(meth)acrylate, from 20 to 80% by weight of a poly(meth)acrylate urethane, from 5 to 60% by weight of a specific mono(meth)acrylate monomer and from 0 to 60% by weight of a compound having at least one polymerisable double bond.
According to the U.S. Pat. No. 5,183,870, the choice of the polybutylene glycol di(meth)acrylate is essential to achieve a good compromise between impact strength and low water absorption properties.
Comparative example 7 discloses a composition containing a polyethylene glycol di(meth)acrylate, a dimethacrylate urethane and a tricyclo[5.2.1.0
2,6
]decan-8-yl methacrylate.
The polymer resulting from this composition has a high water absorption level of 3.6%.
The U.S. Pat. No. 5,880,171 discloses photopolymerisable compositions containing:
from 20 to 90%, and preferably at least 50% by weight of an epoxy or polyester urethane oligomer with (meth)acrylate end groups and 5 to 80% by weight of an optional diluent which is a hydrocarbon diol ester with (meth)acrylate and/or tri, tetra or poly(meth)acrylate end groups.
The U.S. Pat. No. 5,566,027 discloses photopolymerisable compositions comprising from 25 to 45% of a polyester urethane oligomer containing several (meth)acrylic groups linked to a polyester oligomer via a urethane group and having a molecular weight of at least 700, from 31 to 70% by weight of a polyfunctional (meth)acrylate with an average molecular weight of at least 700 and from 5 to 55% by weight of a monofunctional (meth)acrylate.
This composition is used as a varnish applied to ophthalmic lenses.
There is no provision for the use of a composition of this type to produce the body of the lens.
Thus it can be seen that many polymerisable compositions leading to materials with refractive index of the order of 1.5 have been proposed in the prior art, without however giving complete satisfaction for producing transparent polymer substrates usable in the optics field.
SUMMARY OF THE INVENTION
A first object of the present invention is thus to provide new compositions of polymerisable monomers leading to transparent polymer substrates able to be substituted for CAD-based polymers, in other words with properties which are overall similar to those of CAD, and preferably better.
The optical substrates must in particular have all the following properties:
high transparency (transmission generally greater than 85%, and preferably greater than or equal to 90%), with an absence of, or only very slight, diffusion of the light,
low density, less than 1.4, preferably less than 1.3 and even better less than 1.2,
refractive index between 1.48 and 1.52,
high Abbe number, greater than or equal to 40, preferably greater than or equal to 45 and even better greater than or equal to 50, so as to avoid chromatic aberrations,
absence of colour after polymerisation, in particular a low yellow index and an absence of yellowing over time,
good impact strength (in particular an uncoated lens should preferably pass the FDA ball dropping test),
good resistance to static stresses,
good scratch resistance,
good suitability for accepting different treatments (deposit of hard, anti-reflection, primary anti-shock coatings, etc.), and particular good suitability for coloration,
good suitability for surface and edge finishing treatments, without the overall geometry of the lens being distorted during such operations,
low water absorption level.
The polymer substrates according to the invention have a water absorption level which is preferably less than 1.5% and more preferably less than 1%.
A second object of the invention is to provide compositions which may be readily and rapidly polymerised, in particular by photopolymerisation or by mixed photo- and thermal polymerisation techniques, so as to reduce the length of the lens production cycle.
The composition of the polymerisable monomers according to the invention comprises:
40 to 95 parts by weight of one or more monomers (I) of formula:
in which
R
1
and R
2
represent H or CH
3
,
A represents a divalent radical of formula:
m
1
and m
2
are each integers varying from 2 to 6, and
5 to 50 parts by weight of a monomer (II) comprising at least one urethane unit and at least two (meth)acrylate functions.
The composition of monomers accordi
Primel Odile
Richard Gilles
Yean Leanirith
Essilor International (Compagnie Generale d'Optique)
Fulbright & Jaworski L.L.P.
Pezzuto Helen L.
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