Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
1999-10-04
2001-11-13
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...
C526S321000, C526S323200, C526S324000, C526S325000, C526S326000, C526S329200, C526S329500, C526S329600, C526S333000, C526S347000
Reexamination Certificate
active
06316569
ABSTRACT:
Objects of the presently claimed invention are:
a novel type of self-light-stabilized photochromic polymer;
photochromic articles constituted wholly or in part of said novel type of polymer;
the preparation of this novel type of polymer.
There exists today various types of photochromic polymers, proposed notably for ophthalmic applications, whose polymer matrix includes at least one photochromic coloring agent. Said photochromic coloring agents generally consist of spiropyrans, spiroxazines or chromenes. They may intervene in combination. The intervention of spiroxazines in combination with one or more chromenes has notably been recommended.
The phenomenon of aging, of photo-fatigue of these photochromic polymers (they gradually loose their photochromic properties) is well-known to the person skilled in the art. With reference to this phenomenon, it has already been proposed to add various types of products into the matrices of said polymers in order to thus improve their resistance to photo-fatigue, i. e. to photostabilize them. It has thus been recommended:
to add, amongst others, tertiary amines in formulations containing spiropyrans (see U.S. Pat. Nos. 3,322,542 and 3,914,510) or spiroxazines (see U.S. Pat. No. 5,266,447);
to add sterically hindered amines in formulations containing spiroxazines (see U.S. Pat. No. 4,720,356). Said amines are known under the designation “HALS” (Hindered Amine Light Stabilizers);
to add a combination of such sterically hindered amines (HALS) and an asymmetric diaryloxalamide in formulations containing a spiroxazine(s)/chromene(s) combination (see U.S. Pat. No. 5,391,327).
These amines, proposed as photostabilizers for photochromic polymers, are generally of a heterocycle-based complex chemical structure and most of them intervene free, dispersed within the matrix of said polymers.
The Applicant presently proposes an original solution to this technical problem of the photostabilization of said photochromic polymers. The Applicant in fact proposes the original intervention of original stabilizers. Said stabilizers, as shall be specified hereinafter, are monomers or oligomers which are active via non-cyclic tertiary amine groups and they intervene chemically bound to the polymer matrix. They are added prior to the development of said polymer matrix by radical polymerization and they intervene, as co-monomer or co-oligomer, in said radical polymerization. They are known chemical compounds proposed for an original use as photochromic polymer photostabilizers. Said photochromic polymers which incorporate them in their structure, in their carbon skeleton, constitute the first object of the present invention.
In other words, the first object of the present invention is photochromic polymers which carry non-cyclic tertiary amine-functionalized pendant groups. Said polymers are photochromic insofar as their matrix includes at least one photochromic coloring agent. (With reference to a preferred class of polymers of the invention, precisions on such photochromic coloring agents which may intervene in a general manner shall be given further on in the present text). Said thermoplastic or thermoreticulated polymers are self-stabilized insofar as the stabilizers that they contain are chemically bound to their matrix, insofar as said stabilizers constitute a part of their matrix. Furthermore, said stabilizers are thus homogeneously distributed.
Within the context of a preferred variant of the invention, at least some of said non-cyclic tertiary amine-functionalized pendant groups (namely all of them) are of the [di(substituted)amino][(C
2
-C
3
)alkyl]carboxy type:
and advantageously of the [di(C
1
-C
2
)alkylamino][linear(C
2
-C
3
)alkyl]carboxy type:
It has already been specified above that the photochromic polymers of the invention are thermoplastic ones or thermoreticulated ones. It is possible for the large majority of them to be obtained by radical co-polymerization of a composition including acrylic and/or methacrylic and/or alkenyl, notably vinylic or allylic, monomers and/or oligomers. Such compositions are described in more detail further on in the present text. Characteristically, in order to generate the polymers of the invention, said compositions contain an effective amount of at least one monomer and/or oligomer having a non-cyclic tertiary amine function in its formula.
Within the context of an advantageous variant of the invention, said compositions contain an effective amount of a monomer of the following formula:
in which:
R
1
is hydrogen or a methyl group;
n is 2 or 3;
R
2
and R
3
, identical or different, represent independently a methyl or ethyl group; and are advantageously identical.
Said monomer is particularly preferably of the following formula:
It is a matter of diethylaminoethylmethacrylate or DEAEMA.
Generally, the monomers and/or oligomers which intervene characteristically in the context of the present invention have in their formula, on the one hand, a non-cyclic tertiary amine function (photostabilizing function), and on the other hand, a function which is reactive in the sense of the radical polymerization which generates the stabilized photochromic polymer. Said reactive function is generally of the acrylic, methacrylic or alkenyl type, notably vinylic or allylic. The reactive function co-polymerizes with the reactive functions of the various constituents of the polymer matrix, reactive functions which are generally of the same type (vide supra).
It has been indicated above that said monomers and/or oligomers (having at least one non-cyclic tertiary amine function in their structure) intervene in an effective amount. This amount is generally between 0.05 and 5% by weight, and advantageously between 0.2 and 0.6% by weight of the weight of the composition to be polymerized.
It is now proposed to describe a preferred variant of polymers of the invention in greater detail. Said preferred polymers are obtained by radical co-polymerization of a composition containing:
(a) at least one monomer of formula (I):
in which R=H or CH
3
and m and n are independently 1 or 2;
(b) at least one aromatic monovinyl monomer of formula (II):
in which R
1
=H or CH
3
; said monovinyl monomer advantageously consisting of styrene;
(c) an effective amount of at least one photochromic coloring agent conferring photochromic properties to said polymer; said coloring agent being selected from the group consisting of spiroxazines, spiropyrans and chromenes, and advantageously consisting of at least one spiroxazine, of at least one chromene, or a mixture of spiroxazine(s)/chromene(s);
(d) an effective amount of at least one monomer and/or oligomer having at least one non-cyclic tertiary amine function in its formula; said monomer advantageously being of the formula below:
in which:
R
1
is hydrogen or a methyl group;
n is 2 or 3;
R
2
and R
3
are identical or different and represent independently a methyl or ethyl group; and are advantageously identical.
Said composition generally further contains an effective amount of at least one chain transfer agent and an effective amount of at least one radical polymerization initiator. The composition may also further contain:
(e) at least one aromatic divinyl monomer of formula (III):
in which R
1
=H or CH
3
;
said divinyl monomer advantageously consisting of divinylbenzene, and/or
(f) at least one (meth)acrylic monomer of formula (IV):
CH
2
═C(R)—COOR′
in which R=H or CH
3
and R′ is a straight-chain or branched alkyl radical having from 4 to 16 carbon atoms, an optionally substituted (generally by a C
1
-C
6
alkyl group) methylphenyl or methylphenoxy radical or polyoxyethoxylated group of formula:
—(CH
2
—CH
2
—O)
n
R″
in which n is an integer between 1 to 10 and R″=CH
3
or C
2
H
5
;
said (meth)acrylic monomer advantageously consisting of ethylhexylmethacrylate, and/or
at least one plasticizer, advantageously selected from the phthalates and even more advantageously selected from the steri
Henry David
LaFosse Xavier
Corning S.A.
Nwaneri Angela N.
Pezzuto Helen L.
Rogalskyj Peter
LandOfFree
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