Compositions – Light transmission modifying compositions – Displaying color change
Reexamination Certificate
1999-11-12
2001-04-24
Tucker, Philip (Department: 1712)
Compositions
Light transmission modifying compositions
Displaying color change
C351S163000, C524S095000, C524S104000, C524S110000
Reexamination Certificate
active
06221284
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to new transparent, photochromic and non-photochromic organic materials, which have a high refractive index with no optical distortion in the mass, to a process for their preparation, and to articles formed from these materials.
The production of a photochromic ophthalmic lens made of plastic material is very difficult. Ideally, the polymer matrix of such a lens should be thermally crosslinked, should be free of optical distortion in the mass, and should be capable of receiving and of being crosslinked in the presence of appropriate mixtures of photochromic coloring agents, such as spiroxazines and chromenes, in order to obtain a material with a high initial transmission before exposure and an extensive darkening capacity after exposure, all this with rapid darkening and lightening kinetics. Moreover, the material should have a low thermal dependence, a high fatigue strength, and a high refractive index.
Several materials have been suggested for making such materials. For example, WO-A-92/05209 describes a copolymer, which is free of optical distortions, which is suitable for manufacturing glasses for eyeglasses, which is obtained by radical polymerization of a first monomer having the following formula:
in which a and b are whole numbers from 0 to 4, R
1
and R
2
═H or CH
3
, and R
3
═—O—, —S—, —CO—, —SO
2
—, —CH
2
—, —CH═CH— or CH
3
—C—CH
3
, with a second monomer which can be styrene or a styrene derivative, and optionally, a third monomer which can be an aromatic vinyl compound or an aromatic methacrylate, in the presence of an initiator of the peroxide type and a chain transfer agent chosen from various brominated compounds. While the copolymer of the above reference may provide a polymer matrix for a photochromic article, such as a lens, attempts to incorporate photochromic coloring agents in the copolymerizable composition failed because the coloring agents tend to be destroyed by the peroxide initiator. And even if the peroxide initiator is replaced by a gentler radical polymerization initiator, such as a diazoic compound such as azo-bis-isobutyronitrile, the material which is obtained is still unsatisfactory because the photochromic coloring agents are inhibited by the brominated chain transfer agent which is used, as the present inventors were able to observe.
One method which has been suggested for overcoming the above problems is to incorporate the coloring agents in the matrix after polymerization, for example, by a thermal diffusion process. However, such a process tends to be inefficient, adds to the manufacturing cost of the material and complicates its process of manufacturing.
In order to remedy the above problems, co-pending, co-assigned French Patent Application No. 95 08424, filed Jul. 12, 1995, for “New photochromic organic materials,” (herein incorporated by reference), discloses a new transparent photochromic organic materials having a refractive index greater than 1.55 and free of optical distortions, obtained by radical polymerization of a polymerizable composition containing:
a) 80 to 95 wt % of at least one monomer represented by general formula (I):
in which R═H or CH
3
, and m and n are independently 1 or 2;
b) 5 to 20 wt % of at least one aromatic monovinyl monomer represented by general formula (II):
where R
1
═H or CH
3
c) optionally, up to 10 wt % of an aromatic divinyl monomer represented by the general formula (III):
where R
1
═H or CH
3
.
d) an effective quantity of at least one coloring agent giving the material photochromic properties, chosen from the group of the spiroxazines, spiropyrans and chromenes;
e) an effective quantity of a chain transfer agent; and
f) an effective quantity of a radical polymerization initiator; characterized by the fact that the chain transfer agent is a straight-chain alkanethiol, and the radical polymerization initiator is a diazoic compound, as well as a process for preparation of these photochromic materials and photochromic articles consisting of these materials.
Although the photochromic materials described in the aforementioned French patent application represent a significant advance, there continues to be a need for organic materials which are easier and therefore less costly to form into lenses free of optical defects
SUMMARY OF THE INVENTION
Briefly, the invention relates to new transparent organic photochromic and non-photochromic materials which have a refractive index higher than 1.55 and which are free of optical distortions. In particular, the invention relates to an organic material consisting essentially of a copolymer of:
a) 50 to 90 and preferably 55 to 70 wt % of units derived from at least one monomer represented by general formula (I):
in which R═H or CH
3
, and m and n are independently 1 or 2;
b) 10 to 30 and preferably 15 to 25 wt % of units derived from at least one aromatic monovinyl monomer represented by general formula (II):
where R
1
═H or CH
3
;
c) up to 15 wt. %, preferably 2 to 6 wt. % of units derived from an aromatic divinyl monomer represented by general formula (III):
where R
1
═H or CH
3
;
d) 1 to 20 and preferably 5 to 15 wt % of units derived from at least one (meth)acrylic monomer corresponding to the general formula (IV):
CH
2
═C(R)—COOR′
in which R═H or CH
3
,
R′ is a straight-chain or branched C
4
to C
16
alkyl radical, an alkylaryl radical, or a polyoxyethoxylated group with formula —(CH
2
—CH
2
O)
n
R″ in which n=1 to 10 and R″═CH
3
or C
2
H
5
, and
e) optionally, an effective quantity of at least one coloring agent giving desired photochromic properties, chosen from the group of the spiroxazines, spiropyrans and chromenes.
In another aspect, the invention relates to an organic photochromic and non-photochromic material which further includes at least one non-photochromic coloring agent.
In still another aspect, the invention relates to a process for the preparation of new transparent, organic materials, which have a refractive index greater than 1.55 and which are free of optical distortions, the process consisting of the radical polymerization of a polymerizable composition comprising: (a) the monomers of formulae I, II, III and IV as defined above; (b) optionally, an effective quantity of at least one coloring agent giving the desired photochromic properties, chosen from the group of the spiroxazines, spiropyrans and chromenes; (c) optionally, an effective quantity of at least one chain transfer agent chosen from a group consisting of the straight-chain alkanethiols, the alkanethiols substituted by at least one aryl or a radical, and the thiophenols; (d) an effective quantity of at least one radical polymerization initiator, and (e) optionally, a hindered amine light stabilizer.
In a further aspect, the invention relates to a method of making aa transparent organic material having a base tint by first forming a transparent organic material by the radical polymerization of components (a) through (e) as above, and subsequently applying a non-photochromic dye to the photochromic material. In yet another aspect, the non-photochromic dye is combined with the polymerizable matrix so that the resulting photochromic material combines both photochromic and non-photochromic dyes.
For the purposes of the present invention, the term “(meth)acrylic” means acrylic or methacrylic; and for ease of discussion, “organic material” means either photochromic or non-photochromic transparent organic materials.
DETAILED DESCRIPTION OF THE INVENTION
The organic material of the invention is characterized by having a refractive index greater than 1.55, and which is prepared by the radical polymerization of a plastic matrix. In the preferred embodiment, the coloring agent is incorporated in the polymerizable composition to obtain directly, after polymerization, and optionally, an organic material having desired properties. As a variant, it is also possible to produce the organic material by first preparing a nonphotochromic material by poly
Florent Frederic H.
Henry David
LaFosse Xavier
Corning Incorporated
Nwaneri Angela N.
Rogalskyj Peter
Tucker Philip
LandOfFree
Organic photochromic materials does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Organic photochromic materials, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Organic photochromic materials will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2492755