Optics: eye examining – vision testing and correcting – Spectacles and eyeglasses – Ophthalmic lenses or blanks
Reexamination Certificate
2002-04-15
2004-03-02
Lovering, Richard D. (Department: 1712)
Optics: eye examining, vision testing and correcting
Spectacles and eyeglasses
Ophthalmic lenses or blanks
C252S586000, C264S001320, C359S241000
Reexamination Certificate
active
06698883
ABSTRACT:
This application is a 371 of PCT/JP 01/04608 filed May 31, 2001.
BACKGROUND ART
The present invention relates to a novel photochromic cured product having excellent photochromic properties and base material properties, and to a curable composition that gives the above cured product.
Photochromism is a phenomenon that is drawing attention in the past several years, and is a reversible action in that a compound quickly changes its color when it is irradiated with light containing ultraviolet rays such as of sunlight or light of a mercury lamp, and resumes its initial color when it is no longer irradiated with light and is placed in a dark place. The compound having such properties is called photochromic compound. A variety of compounds have heretofore been synthesized without, however, any particular common nature in their structures.
The present inventors have forwarded the study concerning a series of photochromic compounds, have succeeded in synthesizing novel photochromic compounds such as fulgimide compounds, spirooxazine compounds and chromene compounds, have discovered that these compounds exhibit excellent photochromic properties, and have already proposed them.
Through the study conducted by the present inventors up to now, it has been learned that the photochromic properties such as color density and fading rate of the photochromic compounds are retarded to a considerable degree in high molecules as compared to those in a solution. This phenomenon becomes conspicuous particularly when the compound has photochromic molecules of large sizes. The occurrence of this phenomenon is attributed to that a free space in which the molecules of the photochromic compound are allowed to freely move is very smaller in a matrix such as of high molecules than in a solution.
In order to solve this problem, it can be contrived to soften the base material by lowering the glass transition temperature of a high-molecular material that constitutes a matrix, or to expand free space in the matrix.
When a base material having a low glass transition temperature is simply used, however, the hardness is lost arousing a problem when the composition is used for such applications as lenses that require hardness. Further, when the high-molecular material having a large free space is used as a matrix, the hardness usually varies to a large extent depending upon the temperature. Namely, a relatively high hardness may be exhibited near room temperature but the hardness sharply decreases as the temperature rises (hereinafter also referred to as “heat resistance is low”), and the shock resistance decreases, too.
For example, the specification of U.S. Pat. No. 5,739,243 teaches a system of a combination of an alkylene glycol dimethacrylate of a predetermined long chain and a polyfunctional methacrylate having not less than three radically polymerizable groups. According to this combination, the color density and the fading rate are improved to a considerable degree, which, however, are not still satisfactory, and it is desired to further improve the properties. Besides, the above technology is to obtain a base material having excellent flexibility. Therefore, the base materials concretely demonstrated in the Examples have low hardnesses, permit heat resistance to decrease, and involve much optical distortion.
The specification of U.S. Pat. No. 5,811,503 teaches a system of a combination of a long-chain alkylene glycol dimethacrylate, a dimethacrylate and a polyfunctional methacrylate having three or more radically polymerizable groups. However, even this combination has room for improvement concerning the color-developing rate and fading rate. Like those described above, further, the hardness of the base material decreases, heat resistance decreases, and optical distortion is much involved.
Further, the specification of U.S. Pat. No. 5,708,064 discloses a combination of a dimethacrylate using bisphenol A as a skeleton and a monofunctional alkylene glycol methacrylate. Though this combination exhibits considerably good color-developing sensitivity and fading rate which constitute photochromic properties, there still remains room for further improvement.
As described above, photochromic properties and base material properties have not all been satisfied yet.
DISCLOSURE OF THE INVENTION
It is therefore an object of the present invention to provide a photochromic cured product having excellent photochromic properties such as a high color density and a high fading rate, as well as excellent base material properties such as a high hardness and a high heat resistance.
The present invention was proposed in order to achieve the above-mentioned object, and was completed based on a knowledge that when a combination of a particular allyl ether or allylthio ether compound and other radically polymerizable monomer, is mixed with a photochromic compound and when the thus obtained curable composition is cured to obtain a cured product, there are exhibited excellent photochromic properties such as a high color density and a large fading rate and, besides, excellent base material properties are exhibited, such as a high hardness and a high heat resistance.
That is, the present invention is concerned with a curable composition comprising:
(A) an allyl ether or allylthio ether compound represented by the following general formula (1),
wherein R
1
and R
2
are, independently from each other, hydrogen atoms or alkyl groups, R
3
is an alkyl group, an acyl group, an acryloyl group, a methacryloyl group, a vinyl group or a styryl group, Z is an oxygen atom or a sulfur atom, and a and b are, independently from each other, from 0 to 20 in average, a+b being from 3 to 20;
(B) a radically polymerizable monomer other than (A) above; and
(C) a photochromic compound.
Another invention is concerned with a photochromic cured product obtained by curing the above curable composition.
BEST MODE FOR CARRYING OUT OF THE INVENTION
An allyl ether or allylthio ether compound used for the curable composition of the present invention is represented by the following general formula (1),
wherein R
1
and R
2
are, independently from each other, hydrogen atoms or alkyl groups, R
3
is an alkyl group, an acyl group, an acryloyl group, a methacryloyl group, a vinyl group or a styryl group, Z is an oxygen atom or a sulfur atom, and a and b are, independently from each other, from 0 to 20 in average, a+b being from 3 to 20.
Owing to the use of the above allyl ether or allylthio ether compound, the photochromic cured product obtained by curing the curable composition of the present invention exhibits a very high color density and a markedly high fading rate.
Many of the existing curable compositions that have been known for their relatively excellent photochromic properties, exhibit low hardnesses and low heat resistances even after they have been cured. However, the curable composition of the present invention using the above-mentioned particular monomer does not permit the hardness and heat resistance to decrease greatly after it has been cured. Therefore, when there is used a monomer that could become a cured product of a high hardness as other radically polymerizable monomer that is to be copolymerized, it is made possible to obtain a photochromic cured product exhibiting excellent photochromic properties such as a high color density and a high fading rate, as well as a high hardness and a high heat resistance.
Here, it is desired that R
1
and R
2
are alkyl groups having 1 to 5 carbon atoms and, particularly, alkyl groups having 1 to 2 carbon atoms, such as methyl groups or ethyl groups.
It is further desired that R
3
is an alkyl group same as the one denoted by R
1
and R
2
. It is desired that the acyl group is the one having 2 to 15 atoms, such as acetyl group, propionyl group, butyryl group, benzoyl group or naphthoyl group.
The monomer represented by the above-mentioned general formula (1) is usually obtained in the form of a mixture of molecules of different molecular weights. Therefore, a and b representing the numbers of t
Momoda Junji
Nagou Hironobu
Otani Toshiaki
Lovering Richard D.
Sherman & Shalloway
Tokuyama Corporation
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