Title of Invention

"A PROCESS FOR POLYMERISATION OF DIETHYLENE GLYCOL BIS ALLYL CARBONATE"

Abstract This invention relates to a process for polymerization of diethylene glycol bis allyl carbonate which may advantageously be employed for producing plastic lenses having a low refractive index comprising in the step of subjecting diethylene glycol bis allyl carbonate to the step of gamma radiation in the presence of diiso propyl peroxydicarbonate as a catalyst for a period of 8 to 10 hours at radiation of 75 to 85 KGy.
Full Text FIELD OF INVENTION
This invention relates to a process for polymerisation of diethylene glycol bis allyl carbonate. The polymerised carbonate may be used for lenses having a low refractive index.
BACKGROUND OF INVENTION
Plastic ophthalmic lenses are classified by their refractive index, and the refractive index defines the power of the lens.
Hitherto, lenses having a low refractive index (1.52) was normally made by the thermal polymerisation of diethylene glycol bis allyl carbonate. The process consisted in subjecting diethylene glycol bis allyl carbonate to the step of thermal polymerisation in the presence of thermal initiator normally comprising diiso propyl peroxydicarbonate. Such a thermal polymerisation consisted of a thermal cycle at different temperatures.
A disadvantage associated with such a known process is that of high power consumption and time consuming.
OBJECTS OF THE INVENTION
An object of this invention is to propose an improved process for polymerisation of diethylene glycol bis allyl carbonate which may advantageously be used for the manufacture of opthalmic lenses of low refractive index.Another object of this invention is to propose for polymerization of diethylene glycol carbonate which avoids a high power consumption as associated with the known process.
Another object of this invention is to propose for polymerization of diethylene glycol carbonate which may advantageously be used for the manufacture of ophthalmic lenses having good optical properties.
Yet another object of this invention is to propose for polymerization of diethylene glycol bis allyl carbonate, which is different.
DESCRIPTION OF INVENTION
According to this invention there is provided a process for polymerization of diethylene glycol bis allyl carbonate which may advantageously be employed for producing plastic lenses having a low refractive index comprising in the step of subjecting diethylene glycol bis allyl carbonate to the step of gamma radiation in the presence of diiso propyl peroxydicarbonate as a catalyst for a period of 8 to 10 hours at radiation of 75 to85 KGy.
In accordance with this invention the process of polymerization comprises in the step of gamma radiation in distinction to the known process of thermal polymerization. Specifically, the present invention envisages in subjecting diethylene glycol bis allyl carbonate to the step of gamma radiation in the presence of said catalyst for a period of 8 to 10 hours and at a radiation dose of 75 to 85 KGy. If, the dose is increased to more than 85K KGy, then the lens has a yellowish colour. However, if the dose is below 75KGy, the polymerization is incomplete.
Preferably, 1 to 1.5% of catalyst is used in the said step of polymerization. Further objects and advantages are apparent from the ensuing examples :
EXAMPLE 1
Diethylene glycol bis allyl carbonate also known as CR-39 is taken and mixed with 1.2% of diiso propyl peroxy carbonate also known as IPP. The mixture is taken in a syringe and injected into glass blanks fitted in a gasket. The mold containing the polymerization mixture is exposed to gamma radiation of 15-85 klay.
The glass blanks turned dark known on exposure to gamma irradiation, colorless, clean and transparent lenses having a refractive index of 1.52, transmittance greater than 90% and Barcol hardness of 40 was obtained.







WE CLAIM:
1. A process for polymerization of diethylene glycol bis allyl carbonate which may advantageously be employed for producing plastic lenses having a low refractive index comprising in the step of subjecting diethylene glycol bis allyl carbonate to the step of gamma radiation in the presence of diiso propyl peroxydicarbonate as a catalyst for a period of 8 to 10 hours at radiation of 75 to 85 KGy.
2. A process as claimed in claim 1 wherein the catalyst is present in an amount of 1 to 1.5%.
3. A process for polymerization of diethylene glycol bis allyl carbonate as herein described.

Documents:

99-DEL-2005-Abstract-(02-12-2010).pdf

99-del-2005-abstract.pdf

99-DEL-2005-Claims-(02-12-2010).pdf

99-del-2005-claims.pdf

99-DEL-2005-Correspondence-Others-(02-12-2010).pdf

99-del-2005-correspondence-others.pdf

99-del-2005-correspondence-po.pdf

99-DEL-2005-Description (Complete)-(02-12-2010).pdf

99-del-2005-description (complete).pdf

99-del-2005-form-1.pdf

99-del-2005-form-18.pdf

99-del-2005-form-2.pdf

99-DEL-2005-Form-3-(02-12-2010).pdf

99-DEL-2005-GPA-(02-12-2010).pdf

99-DEL-2005-Petition 137-(02-12-2010).pdf


Patent Number 245147
Indian Patent Application Number 99/DEL/2005
PG Journal Number 01/2011
Publication Date 07-Jan-2011
Grant Date 04-Jan-2011
Date of Filing 17-Jan-2005
Name of Patentee SHRIRAM INSTITUTE FOR INDUSTRIAL RESEARCH
Applicant Address 19, UNIVERSITY ROAD, DELHI-110 007, INDIA
Inventors:
# Inventor's Name Inventor's Address
1 RAKESH KUMAR KHANDAL SHRIRAM INSTITUTE FOR INDUSTRIAL RESEARCH, 19, UNIVERSITY ROAD, DELHI-110 007, INDIA
2 GAURI SHANKAR JHA SHRIRAM INSTITUTE FOR INDUSTRIAL RESEARCH, 19, UNIVERSITY ROAD, DELHI-110 007, INDIA
3 GEETHA SESHADRI SHRIRAM INSTITUTE FOR INDUSTRIAL RESEARCH, 19, UNIVERSITY ROAD, DELHI-110 007, INDIA
PCT International Classification Number C08F 2/16
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA