Title of Invention	APROCESS FOR THE PREPARATION OF 2-CHLORO-1,1,1,2-TETRA FLUORO ETHANE BASED SUPERHEATED EMULSION
Abstract	The present invention relates to a process for preparation of 2-chloro-1,1,1,2-tera fluoro-ethane (HCFC-124) based superheated emulsion suspended in host matrix as droplet material. The host matrix is specially prepared elastic polyactylamide gel having viscosity of 15 to 25 lakh cp at a temperature of 20°C -25°C. The superheated emulsion of the present invention is stable at ambient temperature. The size of the droplet is about 10 µm and the size of the bubbles formed on detection of neutron is about 200 µm. It is a highly sensitibe neutron detector and responds to neutrons even at 5°C.

Title of Invention

APROCESS FOR THE PREPARATION OF 2-CHLORO-1,1,1,2-TETRA FLUORO ETHANE BASED SUPERHEATED EMULSION

Abstract

The present invention relates to a process for preparation of 2-chloro-1,1,1,2-tera fluoro-ethane (HCFC-124) based superheated emulsion suspended in host matrix as droplet material. The host matrix is specially prepared elastic polyactylamide gel having viscosity of 15 to 25 lakh cp at a temperature of 20°C -25°C. The superheated emulsion of the present invention is stable at ambient temperature. The size of the droplet is about 10 µm and the size of the bubbles formed on detection of neutron is about 200 µm. It is a highly sensitibe neutron detector and responds to neutrons even at 5°C.

Full Text	FIELD OF INVENTION This invention relates to a process for the preparation of 2-chloro-1,1,1,2-tetra fluoro-ethane based superheated emulsion, wherein the emulsion has applications such as neutron detector, refrigerant and fire extinguishant. PRIOR ART Neutrons are difficult to detect because, being uncharged elementary particles they do not ionize matter as they pass through it. It is, therefore, necessary to rely upon some other form of physical reaction to indicate the presence of neutrons. Chlorofluorocarbons (CFCs) are widely used as neutron detectors, apart from neutron detection they have many unique properties. They are low in toxicity, non flammable, non corrosive and compatible with other materials. In addition they offer the thermodynamic and physical properties that make them ideal for a Variety of uses. CFGs have been used as refrigerant in the manufacture of insulation, packaging and cushioning foams; as cleaning agents for metal and electronic components; and in many other applications. Superheated emulsion detectors for neutron detection consist of superheated drops of R-12 or R-114 or R-12 + R-114 refrigerants suspended in a gel or polymer matrix. When neutron interacts with the droplet, it converts into bubble. Number of bubbles formed are co-related to neutron dose. A superheated emulsion, known in the art, is based on freonl2 and freonl2+ freonl 14 suspended in a gel or polymer matrix. The disadvantage of the above emulsion is that the polymer gel matrix used for suspension is a chlorofluoro compound which causes depletion of earth's protective ozone layer. Another disadvantage of the known emulsion is that it's shelf life is only 3 months. A neutron detector as described in US Patent No. 5334840, utilizes a material enriched with boron nitride in Boron - 10, which emits light when acted upon by thermal neutrons. The limitation of the above method is that it requires an elaborate equipment for neutron detection and hence can not be used as a personal neutron dosimeter. Another neutron detector (US Patent No. 5973328) mark use of fissionable material like lithium, uranium, thorium, plutonium and neptunium incorporated in a sol-gel glass medium. The disadvantage of this neutron detector is that it requires fissionable material which is not easily available. Another disadvantage of the above neutron datector is that the set up required for netron detection is very cumbersome. OBJECTS OF PRESENT INVENTIN The main object of the present invention is to propose a process for the preparation of 2-chloro-l,l,l,2-tetra fluoro-ethane based superheated emulsion which is a highly sensitive neutron sensor for personal neutron dosimetry. Another object of the present invention is to propose a process for preparation of 2-chloro-l,l,l,2-tetra fluoro-ethane based superheated emulsion which has 300 times less ozone depletion potential. Yet another object of the present invention is to propose a process for preparation of 2-chloro-l,l,l,2-tetra fluoro-ethane based superheated emulsion which is relatively less sensitive to ambient temperature. Still another object of the present invention is to propose a process for preparation of 2-chloro-l,l,l,2-tetra fluoro-ethane based superheated emulsion which has higher shelf life of more than 6 months. Further object of the present invention is to propose a 2-chloro-l,l,l,2-tetra fluoro-ethane based superheated emulsion wherein the viscosity of the polyacrylamide gel is optimised so that the size of bubbles formed on detection of neutron is small to increase the neutron detection range. Yet further object of the present invention is to propose a 2-chloro-l, 1,1,2-tetra fluoro-ethane based superheated emulsion wherein the 2-chloro-l, 1,1,2-tetra fluoro-ethane based superheated emulsion wherein the bubbles formed on detection of neutron are trapped at site only. DESCRIPTION OF THE INVENTION Acording to this invention there is provided a process for the preparation of 2-chloro-l, 1,1,2-tetra fluoro-ethane based superheared emulsion comprising in the steps of> (a) preparing a polymer by mixing acrylamide solution with initiator such as solution of ammonium persulphate in a pressure reactor under vacuum followed by mechanical stirring. (b) preparation of super heated emulsion by mixing HCFC-124 in liquid form to the polymer prepared in step (a) at high pressure followed by stirring and then releasing the pressure and keeping at low temperature. The process for preparation of 2-ehloro-1,1,1,2-tetra fluoro-ethane based superheated emulsion comprises of the steps of:- (a) Preparation of solution acrylamide A solvent like ethylene glycol and water are mixed in 1:1 ratio in a beaker with stirring. In this solvent mixture acrylamide monomer is dissolved by mixing 20-30% w/v of the solvent mixture, preferably 22-25% w/v of the solvent mixture. (b) Preparation of initiator 8 - 12% preferably 10% solution of ammonium persulphate is prepared by mixing ammonium persulphate in water. (c) Preparation of Polymer The mixture prepared by step (a) is taken in a pressure reactor. To this mixture initiator (prepared by step (b) taken in quantity 0.1 to 0.15% preferably 0.12 to 0.14% is added. Vacuum of the order of 10 is created in the pressure reactor followed by mechanical stirring for about 20 hours. Vacuum is then released and viscosity of the polymer is measured. The desired range of viscosity of the polymer is 15 to 25 lakh cp preferably 20 lakh cp. (d) Preparation of superheated emulsion After obtaining the polymer of required viscosity, vacuum of the order of 10" is again created in the pressure reactor. To this polymer, 7 to 10% by volume preferably 8% by volume of polymer solution, commercially available 2- chloro-l,l,l,2-tetrafluoro-ethane(HCFC- 124) in liquid form is added. To this mixture nitrogen gas is passed till the pressure reactor shows a pressure around 100 psi. Addition of nitrogen helps in liquifying HCFC-124, if any is in gas form. The mixture is then mechanically stirred for about 3 hours at a speed of about 10-15 rpm. The pressure is then released at a slow rate. The pressure reactor is then kept in a freezer at a temperature of about -15°C. After about 20 minutes, the pressure reactor is connected to nitrogen cylinder and nitrogen is passed till pressure is increased to 100 psi. The nitrogen cylinder is then removed and emulsion can be taken out through the nozzle of the pressure reactor. The invention will now be illustrated with a working example which is intended to be illustrative example and is not intended to be taken restrictively to imply any limitation on the scope of the present invention. WORKING EXAMPLE 50 ml of ethylene glycol and 50 ml of water were mixed in a beaker with stirring. In this solvent mixture 25gm of acrylamide monomer was dissolved. Next a 10% ammonium persulphate solution was prepared in distilled water. The solvent mixture of acrylamide was taken in a pressure reactor and 0.1 ml ammonium persulphate solution was added in it. Then a vacuum of 10"2 arm was created in the pressure reactor and the contents were stirred mechanically for 20 hours. The viscosity of the prepared polyacrylamide gel was measured by Brookfield viscometer, which was 20 lakh cp. Then 8.8 ml of commercially available 2-chloro-l,l,l,2-tetra fluoro-ethane (HCFC-124) in liquid form was added. To this mixture nitrogen gas was passed till the pressure reactor showed a pressure of 100 psi. The nitrogen cylinder was then disconnected and polyacrylamide solution with HCFC-124 was mechanically stirred for 3 hours. The pressure was released and the pressure reactor was kept in freezer at -15°C for 20 minutes. Hie pressure reactor was again connected to nitrogen cylinder and nitrogen was allowed to pass till the pressure was 100 psi. 2-chloro-l,l,l,2-tetra fluoro-ethane based superheated emulsion was transferred to glass vials under nitrogen pressure. 2-chloro-l,l,l,2-tetra fluoro-ethane based superheated emulsion was tested with calibrated neutron sources like Am241-Be and Cf52. The super heated emulsion was found to be sensitive even at low temperatures of 5°C. The neutrons upto ljaR could be measured and it was found to be stable at ambient temperature. It is to be understood that the process of the present invention is susceptible to modifications, changes and adaptations by those skilled in the art. Such modifications, changes, adaptations are intended to be within the scope of the present invention which is further set forth under the following claims:- WE CLAIM: 1. A process for the preparation of 2-chloro-1,1,1,2-tetra fluoro-ethane based superheated emulsion comprising in the steps of:- (a) preparing a polymer by mixing acrylamide solution with initiator such as solution of ammonium persulphate in a pressure reactor under vacuum followed by mechanical stirring. (b) Preparation of super heated emulsion by mixing HCFC-124 in liquid form to the polymer prepared in step (a) at high pressure followed by stirring and then releasing the pressure and keeping at low temperature. 2. A process as claimed in claime 1 wherein the acrylamide solution is prepared in a soluent and water . 3. A process as claimed in claid 1 wherein the initiator is prepared by mixing 8 to 12% of ammonium persulphate in water. 4. A process as claimed in claim 2 wherein the solvent and water are mixed in a ratio of 1:1 by stirring. 5. A process as claimed in claim 2 wherein the solvent is such as ethylene glycol. 6. A process as claimed in claim 1 wherein the acrylamide monomer is taken as 20-30%w/v preferably 22-25% w/v of the solvent mixture. 7. A process as claimed in claim 1 wherein acrylamide solution is mixed with 0.1-0.15% perferably 0.12-0.14% of the initiator. 8. A process as claimed in claim 1 wherein the viscosity of the polymer is 15-25 lakh cp preferably 20 lakh cp. 9. A process as claimed in claim 1 wherein 7-10% preferably 8% of HCFC-124 by volume of polymer solution is added to the polymer. 10. A process as claimed in claim 1 wherein the high pressure of the polymer solution and HCFC-124 is of the order of 100 psi. 11. A process as claimed in claim 1 wherein the high pressure is created by introduction of introgen gas. 12. A process as claimed in claim 1 wherein thestirring of polymer solution and HCFC-124 is carried out at 10-15 rpm for about 3 hours. 13. A process as claimed in claim 1 wherein the ressure reactor with polymer and HCFC-124 is kept at a low temperature of the order of -15°C for about 20 minutes. 14. A 2-chloro-1,1,1,2-tetra fluoro-ethane based superheated emulsion as prepared by the process substantially described and illustrated herein.

Full Text

FIELD OF INVENTION
This invention relates to a process for the preparation of 2-chloro-1,1,1,2-tetra fluoro-ethane based superheated emulsion, wherein the emulsion has applications such as neutron detector, refrigerant and fire extinguishant.
PRIOR ART
Neutrons are difficult to detect because, being uncharged elementary particles they do not ionize matter as they pass through it. It is, therefore, necessary to rely upon some other form of physical reaction to indicate the presence of neutrons. Chlorofluorocarbons (CFCs) are widely used as neutron detectors, apart from neutron detection they have many unique properties. They are low in toxicity, non flammable, non corrosive and compatible with other materials. In addition they offer the thermodynamic and physical properties that make them ideal for a Variety of uses. CFGs have been used as refrigerant in the manufacture of insulation, packaging and cushioning foams; as cleaning agents for metal and electronic components; and in many other applications. Superheated emulsion detectors for neutron detection consist of superheated drops of R-12 or R-114 or R-12 + R-114 refrigerants suspended in a gel or polymer matrix. When neutron interacts with the droplet, it converts into bubble. Number of bubbles formed are co-related to neutron dose.
A superheated emulsion, known in the art, is based on freonl2 and freonl2+ freonl 14 suspended in a gel or polymer matrix.
The disadvantage of the above emulsion is that the polymer gel matrix used for suspension is a chlorofluoro compound which causes depletion of earth's protective ozone layer.
Another disadvantage of the known emulsion is that it's shelf life is only 3 months.
A neutron detector as described in US Patent No. 5334840, utilizes a material enriched with boron nitride in Boron - 10, which emits light when acted upon by thermal neutrons.
The limitation of the above method is that it requires an elaborate equipment for neutron detection and hence can not be used as a personal neutron dosimeter.
Another neutron detector (US Patent No. 5973328) mark use of fissionable material like lithium, uranium, thorium, plutonium and neptunium incorporated in a sol-gel glass medium.
The disadvantage of this neutron detector is that it requires fissionable material which is not easily available.
Another disadvantage of the above neutron datector is that the set up required for netron detection is very cumbersome.
OBJECTS OF PRESENT INVENTIN
The main object of the present invention is to propose a process for the preparation of 2-chloro-l,l,l,2-tetra fluoro-ethane based superheated emulsion which is a highly sensitive neutron sensor for personal neutron dosimetry.
Another object of the present invention is to propose a process for preparation of 2-chloro-l,l,l,2-tetra fluoro-ethane based superheated emulsion which has 300 times less ozone depletion potential.
Yet another object of the present invention is to propose a process for preparation of 2-chloro-l,l,l,2-tetra fluoro-ethane based superheated emulsion which is relatively less sensitive to ambient temperature.
Still another object of the present invention is to propose a process for preparation of 2-chloro-l,l,l,2-tetra fluoro-ethane based superheated emulsion which has higher shelf life of more than 6 months.
Further object of the present invention is to propose a 2-chloro-l,l,l,2-tetra fluoro-ethane based superheated emulsion wherein the viscosity of the polyacrylamide gel is optimised so that the size of bubbles formed on detection of neutron is small to increase the neutron detection range.
Yet further object of the present invention is to propose a 2-chloro-l, 1,1,2-tetra fluoro-ethane based superheated emulsion wherein the 2-chloro-l, 1,1,2-tetra fluoro-ethane based superheated emulsion wherein the bubbles formed on detection of neutron are trapped at site only.
DESCRIPTION OF THE INVENTION
Acording to this invention there is provided a process for the preparation of 2-chloro-l, 1,1,2-tetra fluoro-ethane based superheared emulsion comprising in the steps of>
(a) preparing a polymer by mixing acrylamide solution with initiator such as solution of ammonium persulphate in a pressure reactor under vacuum followed by mechanical stirring.
(b) preparation of super heated emulsion by mixing HCFC-124 in liquid form to the polymer prepared in step (a) at high pressure followed by stirring and then releasing the pressure and keeping at low temperature.
The process for preparation of 2-ehloro-1,1,1,2-tetra fluoro-ethane based superheated emulsion comprises of the steps of:-
(a) Preparation of solution acrylamide
A solvent like ethylene glycol and water are mixed in 1:1 ratio in a beaker with stirring. In this solvent mixture acrylamide monomer is dissolved by mixing 20-30% w/v of the solvent mixture, preferably 22-25% w/v of the solvent mixture.
(b) Preparation of initiator
8 - 12% preferably 10% solution of ammonium persulphate is prepared by mixing ammonium persulphate in water.
(c) Preparation of Polymer
The mixture prepared by step (a) is taken in a pressure reactor. To this mixture initiator (prepared by step (b) taken in quantity 0.1 to 0.15% preferably 0.12 to 0.14% is added. Vacuum of the order of 10 is created in the pressure reactor followed by mechanical stirring for about 20 hours.
Vacuum is then released and viscosity of the polymer is measured.
The desired range of viscosity of the polymer is 15 to 25 lakh cp preferably
20 lakh cp.
(d) Preparation of superheated emulsion
After obtaining the polymer of required viscosity, vacuum of the order of 10"
is again created in the pressure reactor. To this polymer, 7 to 10% by volume
preferably 8% by volume of polymer solution, commercially available 2-
chloro-l,l,l,2-tetrafluoro-ethane(HCFC-
124) in liquid form is added. To this mixture nitrogen gas is passed till the pressure reactor shows a pressure around 100 psi. Addition of nitrogen helps in liquifying HCFC-124, if any is in gas form. The mixture is then mechanically stirred for about 3 hours at a speed of about 10-15 rpm. The pressure is then released at a slow rate. The pressure reactor is then kept in a freezer at a temperature of about -15°C. After about 20 minutes, the pressure reactor is connected to nitrogen cylinder and nitrogen is passed till pressure is increased to 100 psi. The nitrogen cylinder is then removed and emulsion can be taken out through the nozzle of the pressure reactor.
The invention will now be illustrated with a working example which is intended to be illustrative example and is not intended to be taken restrictively to imply any limitation on the scope of the present invention.
WORKING EXAMPLE
50 ml of ethylene glycol and 50 ml of water were mixed in a beaker with stirring. In this solvent mixture 25gm of acrylamide monomer was dissolved. Next a 10% ammonium persulphate solution was prepared in distilled water. The solvent mixture of acrylamide was taken in a pressure reactor and 0.1 ml ammonium persulphate solution was added in it. Then a vacuum of 10"2 arm was created in the pressure reactor and the contents were stirred mechanically for 20 hours. The viscosity of the prepared polyacrylamide gel was measured by Brookfield viscometer, which was 20 lakh cp. Then 8.8 ml of commercially available 2-chloro-l,l,l,2-tetra fluoro-ethane (HCFC-124) in liquid form was added. To this mixture nitrogen gas was passed till the pressure reactor showed a pressure of 100 psi. The nitrogen cylinder was then disconnected and polyacrylamide solution with HCFC-124 was mechanically stirred for 3 hours. The pressure was released and the pressure reactor was kept in freezer at -15°C for 20 minutes. Hie pressure reactor was again connected to nitrogen cylinder and nitrogen was allowed to pass till the pressure was 100 psi. 2-chloro-l,l,l,2-tetra fluoro-ethane based superheated emulsion was transferred to glass vials under nitrogen pressure.
2-chloro-l,l,l,2-tetra fluoro-ethane based superheated emulsion was tested with calibrated neutron sources like Am241-Be and Cf52. The super heated emulsion was found to be sensitive even at low temperatures of 5°C. The neutrons upto ljaR could be measured and it was found to be stable at ambient temperature.

It is to be understood that the process of the present invention is susceptible to modifications, changes and adaptations by those skilled in the art. Such modifications, changes, adaptations are intended to be within the scope of the present invention which is further set forth under the following claims:-

WE CLAIM:
1. A process for the preparation of 2-chloro-1,1,1,2-tetra fluoro-ethane based
superheated emulsion comprising in the steps of:-
(a) preparing a polymer by mixing acrylamide solution with initiator such as solution of ammonium persulphate in a pressure reactor under vacuum followed by mechanical stirring.
(b) Preparation of super heated emulsion by mixing HCFC-124 in liquid form to the polymer prepared in step (a) at high pressure followed by stirring and then releasing the pressure and keeping at low temperature.

2. A process as claimed in claime 1 wherein the acrylamide solution is prepared in a soluent and water .
3. A process as claimed in claid 1 wherein the initiator is prepared by mixing 8 to 12% of ammonium persulphate in water.
4. A process as claimed in claim 2 wherein the solvent and water are mixed in a ratio of 1:1 by stirring.
5. A process as claimed in claim 2 wherein the solvent is such as ethylene glycol.
6. A process as claimed in claim 1 wherein the acrylamide monomer is taken as 20-30%w/v preferably 22-25% w/v of the solvent mixture.
7. A process as claimed in claim 1 wherein acrylamide solution is mixed with 0.1-0.15% perferably 0.12-0.14% of the initiator.
8. A process as claimed in claim 1 wherein the viscosity of the polymer is 15-25 lakh cp preferably 20 lakh cp.
9. A process as claimed in claim 1 wherein 7-10% preferably 8% of HCFC-124 by volume of polymer solution is added to the polymer.
10. A process as claimed in claim 1 wherein the high pressure of the polymer
solution and HCFC-124 is of the order of 100 psi.
11. A process as claimed in claim 1 wherein the high pressure is created by introduction of introgen gas.
12. A process as claimed in claim 1 wherein thestirring of polymer solution and HCFC-124 is carried out at 10-15 rpm for about 3 hours.
13. A process as claimed in claim 1 wherein the ressure reactor with polymer and
HCFC-124 is kept at a low temperature of the order of -15°C for about 20
minutes.
14. A 2-chloro-1,1,1,2-tetra fluoro-ethane based superheated emulsion as
prepared by the process substantially described and illustrated herein.

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Patent Number

277195

Indian Patent Application Number

1229/DEL/2002

PG Journal Number

48/2016

Publication Date

18-Nov-2016

Grant Date

15-Nov-2016

Date of Filing

09-Dec-2002

Name of Patentee

DIRECTOR GENERAL

Applicant Address

B-341, SENA BHAWAN DHQ P.O. NEW DELHI-110011.

Inventors:

#	Inventor's Name	Inventor's Address
1	SHYAM GOVIND VAIJAPURKAR	DEFENCE LABORATORY, RATANADA PALACE, JODHPUR -342011
2	KANA RAM SENWAR	DEFENCE LABORATORY, RATANADA PLACE, JODHPUR-342011

PCT International Classification Number

C07C

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA