Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From reactant having at least one -n=c=x group as well as...
Reexamination Certificate
2002-11-20
2004-02-24
Dawson, Robert (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From reactant having at least one -n=c=x group as well as...
C528S109000, C528S377000, C528S378000, C528S392000, C549S015000, C549S018000, C549S019000, C549S024000
Reexamination Certificate
active
06696540
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
The present application claims priority under 35 U.S.C. § 119 of Japanese Application No. 2001-362375, filed Nov. 28, 2001, the disclosure of which is expressly incorporated by reference herein in its entirety.
DESCRIPTION
1. Field of the Invention
The present invention relates to an episulfide compound, a method for producing the same, and an optical product made with the same. Generally, the invention relates to an episulfide compound that may give optical materials having a high refractive index and a high Abbe's number and having excellent heat resistance and transparency, to a method for producing the same, and to an optical product made with the same.
2. Background of the Invention
Plastics are used for various optical applications these days, for example, for lenses and others, as being lightweight, difficult to break, and easily colored when compared with glass. Optical plastic materials include poly(diethylene glycol bisallylcarbonate) (CR-39) and poly(methyl methacrylate). These plastics, however, have a refractive index of 1.50 or less. Therefore, for example, when they are used for lens materials, the lenses produced need to be thicker for increased power, and they lose the advantage of being lightweight. In particular, powerful concave lenses are thick at their periphery, and are therefore unfavorable as causing birefringence and chromatic aberration. For spectacles, such thick lenses are often not aesthetic. To obtain thin lenses, materials with higher refractive index may be used. In general, the Abbe's number of glass and plastics decreases with the increase in their refractive index, and, as a result, their chromatic aberration increases. Accordingly, plastic materials having a high refractive index and a high Abbe's number are desired.
Plastic materials proposed as having such properties include, for example, (1) polyurethanes obtained through addition-polymerization of a polythiol having bromine in the molecule and a polyisocyanate (Japanese Patent Laid-Open No.164615/1983); and (2) polythiourethanes obtained through addition-polymerization of a polythiol and a polyisocyanate (Japanese Patent Publication No. 58489/1992 and Japanese Patent Laid-Open No.148340/1993). For the starting material, polythiol for the polythiourethanes of above (2), may be branched polythiols having an increased sulfur content (Japanese Patent Laid-Open Nos. 270859/1990 and 148340/1993), and polythiols into which is introduced a dithiane structure for increasing their sulfur content (Japanese Patent Publication No. 5323/1994 and Japanese Patent Laid-Open No.118390/1995). Other plastic materials proposed as having such properties include (3) polymers of an alkyl sulfide having a polymerization-functional group, episulfide (Japanese Patent Laid-Open Nos. 71580/1997 and 110979/1997).
However, though their refractive index is increased a little, the polyurethanes of above (1) still have a low Abbe's number and have some other drawbacks in that their lightfastness is poor, their specific gravity is high and, therefore, they are not lightweight. Of the polythiourethanes (2), those for which the starting polythiol used has a high sulfur content have an increased refractive index of from about 1.60 to 1.68, but their Abbe's number is lower than that of optical inorganic glass having a refractive index on the same level. Therefore, they still have a problem in that their Abbe's number must be increased more. On the other hand, one example of the alkyl sulfide polymers (3) having an Abbe's number of 36 has an increased refractive index of 1.70. The lenses obtained by using this polymer can be extremely thin and lightweight. However, plastic materials with high Abbe's number and refractive index are still desired.
SUMMARY OF THE INVENTION
The present invention has been made to address the problems noted above. The present invention provides compounds that may give optical materials having a high refractive index and a high Abbe's number and having excellent heat resistance and transparency, a method for producing the same, and an optical product made with the same.
The present inventors have determined that compounds of 1,3,5-trithiane (hereinafter abbreviated as “trithiane”) with an episulfide derivative bonded thereto are useful in solving the above-noted problems, and that the compounds may be efficiently produced in a specific method. Specifically, the invention provides an episulfide compound represented by the general formula (1):
wherein EP represents
and n is an integer of from 0 to 2. The invention also provides a method for producing an episulfide compound represented by the general formula (1) by reacting a mercapto group-containing episulfide compound with 2,4,6-trimethylene-1,3,5-trithiane.
DESCRIPTION OF THE INVENTION
The particulars shown herein are by way of example and for purposes of illustrative discussion of the various embodiments of the present invention only. In this regard, no attempt is made to show details of the invention in more detail than is necessary for a fundamental understanding of the invention, the description making apparent to those skilled in the art how the several forms of the invention may be embodied in practice.
Unless otherwise stated, a reference to a compound or component, includes the compound or component by itself, as well as in combination with other compounds or components, such as mixtures of compounds.
The episulfide compound of the invention is represented by the general formula (1) mentioned below, from which it is seen that the compounds have three, optionally identical, episulfide-containing substituents bonded to the trithiane ring thereof.
wherein EP represents
and n is an integer of from 0 to 2.
The trithiane ring of the episulfide compound represented by the general formula (1) has a high sulfur content, in which the atomic refraction is high and which therefore significantly increases the refractive index of the polymers obtained by using the episulfide compound of the invention. In addition, the ethylene sulfide chain to be formed through ring-cleavage polymerization of the episulfide compound also contributes toward increasing the refractive index of the polymers. In general, the Abbe's number of amorphous materials is apt to decrease with the increase in the refractive index thereof. One problem with polymers having high sulfur content is that the electron resonance of sulfur is remarkable, therefore often significantly reducing the Abbe's number. However, the episulfide compounds of the invention are free from this problem. Another cause of the increase in the refractive index is the decrease in the molar volume thereof. This is often seen in polymers having a high crosslinking density and a strong intermolecular force. The episulfide compound of the invention has three polymerization-functional groups, and the refractive index of its polymers is increased especially by the former effect. In the general formula (1), the increase in the number n lowers the sulfur content and the crosslinking density, therefore giving polymers having a reduced refractive index. Accordingly, n is generally in a range of from 0 to 2. In addition, since the glass transition temperature (Tg) of the polymers obtained by using the episulfide compound of the invention lowers with the increase in n in the general formula (1), n is generally in a range of from 0 to 2 in order to obtain polymers having good heat resistance.
For example, the episulfide compound represented by the general formula (1) of the invention includes 2,4,6-tris(epithiomethylthiomethyl)-1,3,5-trithiane, 2,4,6-tris(epithioethylthiomethyl)-1,3,5-trithiane, and 2,4,6-tris(epithiopropylthiomethyl)-1,3,5-trithiane.
These episulfide compounds of the invention may be efficiently produced according to the method of the invention by reacting 2,4,6-trimethylene-1,3,5-trithiane having a methylene group introduced into its 2,4,6-positions, with a mercapto group-containing episulfide compound at the
Okubo Tsuyoshi
Takamatsu Ken
Aylward D.
Dawson Robert
Finnegan Henderson Farabow Garrett & Dunner LLP
Hoya Corporation
LandOfFree
Episulfide compound, method for producing the same and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Episulfide compound, method for producing the same and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Episulfide compound, method for producing the same and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3335132