Title of Invention

"A PROCESS FOR THE PREPARATION OF PHOTOCROSSLINKABLE POLYARYLENE SULPHIDES"

Abstract A process for the preparation of photocrosslinkable copolysulfides by reacting in an inert atmosphere 2, 6 Bis (4-chloro benzylidene) cyclohexanone with alkali metal sulfides such as herein described and 1,4 dihalo benzene in the presence of a polar aprotic solvent at temperatures in the range of 170 to 220°C for a period ranging from 4 to 12 hours, cooling the reaction mixture to ambient temperature pouring the reactants into acidified alkanol and removing the product by conventional methods, washing with water to remove the unreacted material and by product and drying to obtain photocrosslinkable copolysulfides.
Full Text This invention relates to a process for the preparation of a photocrosslinkable polyarylene sulfides. More particularly it relates to a process for the preparation of polyarylene sulphides soluble in organic solvents and are photocrosslinkable to yield tough films. The photocrosslinkable polyarylene sulphides prepared by the process are new and can be used for high performance coating applications.
Polyphenylene sulfide PPS in an important engineering polymer in the family of polyarylene sulphides. PPS is an high performance polymer with wide range of applications such as corrosion' resistant coatings, pump impeller, ball valves, chemical tower packing and number of molded engineering articles.
PPS is conventionally synthesised by reacting 1,4 dichloro benzene with sodium sulfide in N-methyl pyrollidone at high temperatures and pressures. During the course of the reaction the polymer due to it's insolubility precipitates out of the system. As a consequence of this, the molecular weight of the polymer will not increase beyond the certain range which leads to the broad range molecular weight distribution. Such a low molecular weight PPS is suitable for the coating purposes.
PPS for coating applications is formulated as a dispersion in water along with additives such as fillers, surface active agents, pigments etc. The coatings have to be thermally cured at temperatures in the range of 360 to 400 °C for a period' of ranging from 20 to 45 minutes.
The disadvantnges of thermal curing can be overcome if a photocurable system can be synthesized. The advantages of photo-
curable system are that the process would be techno-economically viable and faster curing times would be possible. This would result in faster processing cycles.
The object of the present invention is to provide a process for the preparation of photocrosslinkable polyarylene polymers.
Another object of the present invention is to provide a process for the preparation of photocrosslinkable polyarylene sulphides of molecular weights in the acceptable range for coating applications that overcome the limitations of thermally curing systems.
Yet another object of the invention is to provide a process for"the preparation of photocrosslinkable polyarylene sulphides that can be cured with UV source to tough films.
Accordingly, the present invention provides a process for the preparation of photocrosslinkable copolysulfides which comprises reacting in an inert atmosphere 2,6 Bis (4-chloro benzylidene) cyclohexanone, alkali metal sulfides and 1,4 dihalo benzene, in the presence of a polar aprotic solvent at temperatures in the range of 170 to 220°C for a period ranging from 4 to 12 hours, cooling the reaction mixture to ambient temperature, pouring the reactants .into acidified alkanol and removing the product by conventional methods, washing with water to remove the unreacted
material and by product and drying to get the final product.
According to an embodiment of the present invention, the inert gas -used may be selected from nitrogen, argon.
According to another feature of the invention, the alkali metal sulfides used may be selected from lithium sulfide, sodium sulfide, or mixture of both.
According to another feature of invention, the 1,4 dihalo
benzene used may be selected from 1,4 dichloro benzene, 1,4-dibromo
benzene or mixtures of the two.
According to yet another feature of invention, the molar ratio of 2,6 bis (4-chloro benzylidene) cyclohexanone to 1,4 dihalo benzene used may be selected from 5% to 50 mol%.
According to yet embodiment of the present invention, the aprotic solvent used may be selected from hexamethylene phosphoramide, N-methyl pyrrolidone, N-hexyl pyrrolidone and -the like but preferably N-methyl pyrrolidone.
According to yet another embodiment of the invention, the concentration of the acid used for precipitation may range from 3 to 5 % and the acid used may be selected from sulphuric acid, nitric acid, hydrochloric acid -and the like.
According to still another embodiment of the invention, the alkanol used may be selected from methanol, ethanol and the like.
The process of the present invention is described with reference to following examples which are illustrative only and should not be construed.to limit the scope of this invention in any manner.
Example 1:
2.57 grams of 2,6 Bis (4-chloro benzylidene) cyclohexanone, 0.36g 1,4 dichloro benzene 0.45g lithium sulfide are mixed in a glass ampoule and 10 ml dry distilled NMP was added to this mixture. The ampoule was sealed under a nitrogen atmosphere. The ampoule was placed in a silicon oil bath at 190°C for 10 hours. At the end of 10 hours the reactants were cooled to ambient temperature. The ampoule was broken and the contents poured into 5% acidified methanol. The precipitate was filtered and washed with water till free from lithium chloride and dried. The yield obtained was 0.75 gram. The product obtained had a melting point of 220°C.
Example 2:
0.85 gram of 2,6 Bis (4-chloro benzylidene) cyclohexanone, 1.76 grams of 1,4 dibromo benzene, 0.76 gram of sodium sulfide are mixed in a glass ampoule and 10 ml dry distilled NMP was added to this mixture. The ampoule was sealed under an atmosphere of argon. The ampoule was placed in a silicon oil bath at 210°C for 6 hours. At the end of 6 hours the reactants were cooled to ambient temperature. The ampoule was broken and the contents poured info 3% acidified ethanol. The precipitate was filtered and
washed with water till free from sodium bromide, sodium chloride
and dried. The yield obtained was 2.65 grams.
The product obtained had a melting point of 240°C.
Example 3:
0.34 gram of 2,6 Bis (4-chloro benzylidene) cyclohexanone 2.11 grams of 1,4 dibromo benzene, 0.22 gram of lithium sulfide, 0.38 gram of sodium sulfide were mixed in a glass ampoule and 10 ml dry distilled NMP was added to this mixture. The ampoule -was sealed under a nitrogen atmosphere. The ampoule was placed in a silicon oil bath at 170°C for 12. hours. At the end of 12 hours the ampoule was cooled to ambient temperature. The ampoule was broken and the contents poured into ethanol acidified with 3 % sulphuric acid. The precipitate was filtered and washed with water till free from sodium bromide, lithium bromide sodium chloride, lithium chloride and dried. The yield obtained was 2.30 grams. The product obtained had a melting point of 260°C.
Example 4 :
0.34 gram of 2,6 Bis (4-chloro benzylidene) cyclohexanone, 0.66 gram .1,4 dichloro benzene, 1.06 gram of 1,4 dibromo benzene, 0.45 gram of lithium sulfide are mixed in a glass ampoule and 10 ml dry distilled NMP was added to this mixture. The ampoule was sealed under a argon atmosphere. The ampoule was placed in a silicon oil bath at 22O°C for 4 hours. At the end of 4 hours the
ampoule was cooled to ambient temperature. The ampoule was broken and the contents poured into methanol acidified with 5 % nitric acid. The precipitate was filtered and washed with water till free from lithium chloride, lithium bromide and dried..The yield
obtained was 2.10 grams.
The product obtained had a melting point of 230°C.
Example 5 :
0.17 gram of 2,6 Bis (4-chloro benzylidene) cyclohexanone, 2.23 gram of 1,4 dibromo benzene, 0.45 gram of lithium sulfide are mixed in a glass ampoule and 10 ml dry distilled N-hexyl pyrollidone was added to this mixture. The ampoule was sealed under a argon atmosphere. The ampoule was placed in a silicon oil bath at 200°C for 8 hours. At the end of 8 hours the ampoule was cooled to ambient temperature. The ampoule was broken and the contents poured into methanol acidified with 5 % nitric acid. The precipitate was filtered and washed with water till free from
lithium chloride, lithium bromide and dried. The yield obtained
was 2.30 grams.
The product obtained had a melting point of 245°C.
Example 6 :
1.71 gram of 2,6 Bis (4-chloro benzylidene) cyclohexanone, 1.17 gram of 1,4 dibromo benzene, 0.45 gram of lithium sulfide are mixed in a glass ampoule and 10 ml dry distilled hexamethylenephosphamide was added to this mixture. The ampoule was sealed under a nitrogen atmosphere. The ampoule was placed in
a silicon oil bath at 180°C for 10 hours. At the end of 10 hours the ampoule was cooled to ambient temperature. The ampoule was broken and the contents poured into ethanol acidified with 5 % hydrochloric acid. The precipitate was filtered and washed with water till free from lithium chloride, lithium bromide and dried. The yield obtained was 2.50 grams. The product obtained had a melting point of 210°C.
Advantages of the present invention :
1. The polymer prepared process of the present invention is
soluble in common organic solvents such as chloroform,
carbon tetrachloride, THF etc.,
2. The polymer obtained by the process of the present invention
can be photocured to tough films unlike the conventional
process wherein high temperatures are required to cure the
material.
3. The photo-curable formulation does not require any
additional fillers.






We claim :
1) A process for the preparation of photocrosslinkable copolysulfides which comprises reacting in an inert atmosphere 2,6 Bis (4-chloro benzylidene) cyclohexanone, alkali metal sulfides and 1,4 dihalo benzene in the presence of a polar aprotic solvent at temperatures in the range of 170 to 220°C for a period ranging from 4 to 12 hours, cooling the reaction mixture to ambient temperature, pouring the reactants into acidified alkanol and removing the product by conventional methods, washing with water to remove the unreacted material and by product and drying to get the final product.
2. A process as claimed in claim 1, wherein the inert gas used
is selected from nitrogen, argon.
3. A process as claimed in claims 1 and 2, wherein the alkali
metal sulfides used is selected from lithium sulfide, sodium
sulfide, or mixture of both.
4. A process as claimed in claims 1 to 3, wherein the 1,4
dihalo benzene used is selected from 1,4 dichloro benzene,
1,4-dibromo benzene or mixtures of the two.
5. A process as claimed in claims 1 to 4, wherein the molar
ratio of 2,6 bis (4-chloro benzylidene) cyclohexanone to 1,4
dihalo benzene used is selected from 5% to 50 mol%.
6. A process as claimed in claims 1 to 5, wherein the aprotic
solvent used yrna-y be selected from hexamethylene
phosphoramide, N-methyl pyrrolidone, N-hexyl pyrrolidone and the like but preferably N-methyl pyrrolidone.
7. A process as claimed in claims 1 to 6, wherein the
concentration of the acid used for precipitation may range
from 3 to 5 % and the acid used is selected from
sulphuric acid, nitric acid, hydrochloric acid and the like.
8. A process as claimed in claims 1 to 7, wherein the alkanol
used/may be selected from methanol, ethanol and the like.
9. A process for the preparation of photocrosslinkable
polyarylene sulphides as substantially described with
reference to the examples.

Documents:

1113-del-1998-abstract.pdf

1113-del-1998-claims.pdf

1113-del-1998-correspondence-others.pdf

1113-del-1998-correspondence-po.pdf

1113-del-1998-description (complete).pdf

1113-DEL-1998-Form-1.pdf

1113-del-1998-form-19.pdf

1113-del-1998-form-2.pdf


Patent Number 214584
Indian Patent Application Number 1113/DEL/1998
PG Journal Number 09/2008
Publication Date 29-Feb-2008
Grant Date 13-Feb-2008
Date of Filing 27-Apr-1998
Name of Patentee COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH
Applicant Address RAFI MARG NEW DELHI-110 001, INDIA
Inventors:
# Inventor's Name Inventor's Address
1 CHELANATTU KHIZHAKKE MADATH RAMAN RAJAN NATIONAL CHEMICAL LABORATORY, PUNE-411 008, MAHARASHTRA, INDIA
2 SURENDRA PONRATHNAM NATIONAL CHEMICAL LABORATORY, PUNE-411 008, MAHARASHTRA, INDIA
3 ALAIN FRADET, LABORATOIRE DE SYNTHESE MACROMOLECULAIRE ,4, PLACE JUSSIEU, 75252 PARIS CEDEX 5, FRANCE
4 SUNITA OMPRAKASH YEMUL NATIONAL CHEMICAL LABORATORY, PUNE-411 008, MAHARASHTRA, INDIA
5 OMPRAKASH SRINIVAS YEMUL NATIONAL CHEMICAL LABORATORY, PUNE-411 008, MAHARASHTRA, INDIA
PCT International Classification Number C08G 075/14
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA