Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2000-02-15
2001-12-11
Lipman, Bernard (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S286000, C526S301000
Reexamination Certificate
active
06329482
ABSTRACT:
The objects of the present invention are:
a radically polymerizable composition based on at least two different types of difunctional monomers;
A resin obtained by copolymerization of the composition; the resin having a nanobiphasic structure and it being possible for the resin to be photochromic or non-photochromic.
articles, notably ophthalmic articles, constituted wholly or in part of the resin.
The creation of a plastic ophthalmic lens is a difficult exercise insofar as it is required that the structure of the lens be free from optical constraints and posses obviously satisfactory mechanical properties. In order to attain this result, it is convenient to perfectly master the copolymerization reactions carried out during the development of the lens. It is in any case necessary to prevent attaining the gel point of the reaction system too quickly in other to avoid the formation of strings and other optical defects as a result of non-uniform polymerization. This is problematic insofar as the basic monomers known to this day are generally symmetrical difunctional monomers.
Furthermore, within the context of the creation of photochromic ophthalmic lenses by either radical polymerization of compositions containing at least one photochromic coloring agent, or by subsequent diffusion of such coloring agents in polymerized matrices, it is appropriate that the structure of the lenses have, in addition
to having good optical properties good photochromic properties without a notable alteration of the mechanical properties of the lens.
It is not easy to obtain an acceptable photochromic properties/mechanical properties compromise. It is the object of the invention to prepare a nanobiphasic structure (in order to prevent phenomena of light-diffusion which affect optical quality) which has a phase that ensures the mechanical rigidity of the structure and another phase which confers sufficient suppleness (or softness) to the structure in order to allow the photochromic coloring agent(s) incorporated within to express their photochromic properties rapidly and at their best.
To our best knowledge, satisfactory compositions have not been prepared (both from the point of view of the expression of the photochromism and from the point of view of the absence of constraints).
It has been proposed, in the applications EP-A-0 453 149 and WO-A-95 10790, to copolymerize two types of monomers which both nevertheless have the same type of reactive functions (acrylate groups and/or methacrylate groups). The result is not very satisfactory in terms of optical properties and ease of manufacturing.
In order to minimize, even prevent the optical constraints, it has been proposed in the patent U.S. Pat. No. 5,349,035 to associate at least one other monomer, notably styrene, to a monomer of the dimethylacrylate type, and to carry out the copolymerization in the presence of an effective amount of a chain transfer agent. However, the matrix obtained is not appropriate for sufficiently expressing or optimizing the photochromic properties of the photochromic coloring agents.
Difunctional monomers have been described in the EP-A-0 345 748 and EP-A-0 351 534 which have a terminal isopropylene function and which are appropriate for the preparation of hard transparent resins. It has also been described in the applications EP-A-0 385 456 and EP-A-0 572 077, short chain plurifunctional monomers and their copolymerization with other functionalized monomers (acrylate, methacrylate, and/or styrene) for preparing transparent resins with high surface hardness. The hard resins, according to these four European patent applications, are orientated towards non-photochromic ophthalmic applications. The monomers are obtained from compounds of formula:
known under the designation TMI®.
Furthermore, an abundant literature exists on the chemistry of such compounds and notably on that of 3-isopropenyl-&agr;,&agr;-dimethylbenzyl isocyanate (compound of the above formula with the two substituents in meta, known under the designation m-TMI®). This chemistry is based upon the reactivity of the isocyanate group.
The Applicant now proposes an original solution to this technical problem of compromise between the optical properties, even photochromic properties, and the mechanical properties of a plastic material usable notably in ophthalmology. The present invention consists of associating at least one long-chain alkenic difunctional monomer with at least one short-chain (meth)acrylic difunctional monomer by radical copolymerization. The resulting resin has then a nanophasic structure, which provides it with the desirable properties. In fact, the short-chain (meth)acrylic difunctional monomer(s) (of type (a) and of formula (A), (A′): below) bring about rigidity, this rigidity being modulated by the presence of the long-chain alkenic difunctional monomer(s) (of type(b) and of formula (B), (B′), (B″): below), which, in a surprising way, also enable providing the composition with excellent photochromic properties. Thus, the synergistic effect of the differences in functionality of the monomers of type (a) and (b) advantageously retard the gelling of the resulting polymerizable composition. This characteristic allows the resulting resin to display good optical properties, and notably in the case where photochromic coloring agents are incorporated within it, to exhibit optimal photochromic properties rapidly.
The first object of the present invention is therefore a radically polymerizable composition comprising a mixture of at least one or more difunctional monomers of type (a) and one or more difunctional monomers of type (b) all as defined below.
The difunctional monomer(s) of type (a) include one or the other of formulae (A) and (A′) below:
Formula (A)
in which:
R
1
, R′
1
, R and R′, identical or different, independently are a hydrogen or a methyl group;
m and n are, independently, integers between 0 and 4 inclusive; and are advantageously independently equal to 1 or 2;
X and X′, identical or different, are a halogen and preferably represent chlorine and/or bromine;
p and q are, independently, integers between 0 and 4 inclusive;
Formula (A′)
in which:
R
1
and R′
1
, identical or different, independently are a hydrogen or a methyl group;
R is a linear or branched alkyl radical having from 2 to 8 carbon atoms, a cycloalkyl radical having from 3 to 6 carbon atoms, an ether radical of formula (R′—O—R″) in which R′ and R″, identical or different, independently are a linear or branched alkyl radical having from 2 to 4 carbon atoms;
The difunctional monomer(s) of type (b)—long-chain alkenic difunctional oligomer—being of one or the other of formulae (B), (B′) and (B″) below:
Formula (B)
in which:
R
1
, R′
1
, R
2
and R′
2
, identical or different, independently are hydrogen or a linear or branched alkyl radical, advantageously linear, having from 1 to 4 carbon atoms and correspond particularly advantageously to a methyl group;
R
3
and R
4
, different, are independently one hydrogen and the other an alkenyl radical having from 2 to 6 carbon atoms, advantageously from 2 to 4 carbon atoms and particularly advantageously an isopropenyl radical
R′
3
and R′
4
, different, are independently one hydrogen and the other an alkenyl radical having from 2 to 6 carbon atoms, advantageously from 2 to 4 carbon atoms and particularly advantageously an isopropenyl radical; (advantageously, the two ends of the molecule are identical; i.e. R
3
═R′
3
and R
4
═R′
4
);
Z represents a carbamate function (—NH—CO—O—), a thiocarbamate function (—NH—CO—S—) or a urea function (—NH—CO—NH—);
Z′, independent from Z and advantageously respectively with respect to Z, represents a carbamate function (—O—CO—NH—), a thiocarbamate function (—S—CO—NH—) or a urea function (—NH—CO—NH—);
R′ represents a linear or branched alkyl radical having from 2 to 4 carbon atoms;
R, identical or different when n≧2, is a linear or branched alkyl r
Corning S.A.
Lipman Bernard
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