Indian Patents. 193324:"AN IMPROVED PROCESS FOR PREPARATION OF CURING AGENT WITH CROSS-LINKING PROPERTIES FOR PROPELLANT FORMULATIONS AND PROCESS OF PREPARATION THEREOF"

Title of Invention	"AN IMPROVED PROCESS FOR PREPARATION OF CURING AGENT WITH CROSS-LINKING PROPERTIES FOR PROPELLANT FORMULATIONS AND PROCESS OF PREPARATION THEREOF"
Abstract	This invention relates to an improved process for preparation of curing agent with cross-linking properties for propellant formulations. The process comprises in reacting a mixture of hydroxy terminated compounds with diisocyanate by heating upto a temperature of 95°C for about 60 minutes.

Full Text	The present invention relates to an improved process for preparation of curing agent with cross-linking properties for propellant formulations. Considerable variety of compounds have already been proposed for the purpose. Cross linking of binding agents preferably polymers to increase their stability and the life in case of propellants or such curing agents for cross linking the hydroxy-terminated polybutadiene, herein after to be named as HTPB, with urethane linkages, isocyanates, terminated compounds like toluene diisocyanate, hexamethylene diisocyanate, dimethyl diisocyanate, isophorone diisocyanate are used as cross linking agents, more particularly curing agents, in the propellant formulations. However, with long chain polymers, particularly copolymers, more particularly block copolymers, even more particularly hydroxy terminated block copolymers, hereinafter to be named as HTBCP, these known such cross linking agents particularly curing agents as stated herein above produce cross linked products of such polymers having poor mechanical properties. Yet another drawback of such curing agents is that the solidification of the end product, i.e. of propellants is not achieved to the desired extent for specific applications for which they are made. Therefore, there is great need for a novel cross linking agent, more particularly a novel curing agent with improved properties to overcome such disadvantages of the known curing agents of the prior art. Accordingly, an object of the present invention is to propose a novel curing-agent which obviates the disadvantages associated with the curing agents of the prior art. Another object of the present invention is to propose a curing agent used for cross linking long chain polymers for better mechanical properties. According to this invention there is provided an improved process for preparation of curing agent with cross-linking properties for propellant formulations wherein the process comprises of heating a mixture of triol and castor oil with a diisocyanate, to a temperature of 85 to 95°C for one hour, adding a polyol, heating further for 45 min to 60 min at 90-100°C obtaining the desired curing agent wherein triol and castor oil are taken in the ratio of 1:1 by weight and diisocyanate is taken in quantity 2 to 3 times the weight of the mixture of castor oil and triol and wherein further triol, polyol and castor oil are in 5:8:5 equivalent weight ratio. According to another preferred embodiment of the present invention, triol, preferably trimethyiol propane having three hydroxy terminated groups, polyol, preferably sorbitol having essentially six hydroxy groups and castor oil, having 2 to 3 hydroxy groups and these hydroxy terminated reactors are preferably taken in the equivalent weight ratio of 5:8:5. According to the proposed method of the present invention, a novel curing agent is provided having isocyanate 15 to 25%. : Another object of the present invention is to propose a curing agent used for cross linking long chain polymers for better mechanical properties. According to this invention there is provided a process for the preparation of a curing agent wi»h improved cross linking properties for propellants comprising in reacting a mixture of hydroxy terminated compounds with diisocyanate. In accordance with the present invention, the novel curing agent is obtained by reacting the mixtures of hydroxy terminated compounds like castor oil, triol, polyol, essentially" With diisocyanate, preferably taken in two or three times in equivalent weight proportion to the total hydroxy value of the mixture of hydroxy terminated compounds. According to another preferred embodiment of the present invention, triol, preferably trimethylol propane having three hydroxy terminated groups, polyol, preferably sorbitol having essentially six hydroxy groups and castor oil, having 2 to 3 hydroxy groups and these hydroxy terminated reactors are preferably taken in the equivalant weight ratio of 5:0:5. According to the proposed method of the present invention, a novel curing agent is provided having isocyanate 15 to 25%. According to another preferred embodiment of the present invention, a novel curing agent is provided, prepared by the present method of invention, more preferably, having viscosity 1000 to 1500 at 25oC. According to still another preferred embodiment of the present invention, a novel cross linking agent, more particularly, a curing agent is disclosed, more particularly for long chain polymers, essentially having hydroxy terminated groups which can also be used for short chain polymers, again having hydroxy terminal groups and these said novel curing agent is also applicable for all class of propellant formulations comprising essentially hydroxy terminated polymers. The proposed method of the present invention for the synthesis of proposed novel curing agent is, the said process comprising of reaction of castor oil, & triol like trimethylol propane in 1:1 ratio with toluene diisocyanate which in turn is taken atleast 2 to 3 times equivalent weight proportion of the total hydroxyl value of mixture of the hydroxy terminated compounds like sorbitol and a triol and a polyol which however in turn are taken in ratio of 8:5:5. The said reaction is carried out in three necked round bottomed flask and fitted with the condenser and thermometer and to add the polyol during the ongoing process after one hour of the reaction time. According to the proposed method, the mixture of diisocyanate, castor oil and trimethylol propane is allowed to heat upto 100°C, preferably between 85 to 100°C for one hour to which the polyol like melted sorbitol which in turn is melted at 90°C is added and heating is allowed for another one hour at preferable temperature of 90°C. The whole synthesis is completed preferably in one hr to 2 hrs time, more preferably 1 1/2 to 2 hrs. The invention is illustrated with the following example which are not intended to limit the scope of the invention and any modification, therein, is considered within the scope of the present inventi en to yield the product for the said purpose. Example 1: Weighed quantity of 45 gms of castor oil, 11 grns of trimethylol propane and i83 grms of toluene diisocyanate are taken in a round bottomed flask of capacity one litre kept on a heating mantle with provision of controlling the heating. The reaction mixture is allowed to heat upto 95°C for 60 minutes. At this stage, the melted 9 gms of sorbitol, melted at 90°C, separately are added to the reaction vessel, i.e three necked round bottom flask and the reaction is allowed to continue for 4 5 minutes at temperature of 100°C. The resulted curing agent is tested for viscosity and isocyanate percentage obtaining viscosity 1200 cps at 25°C at 25°C and isocyanate percentage 18%. I CLAIM: 1. An improved process for preparation of curing agent with cross-linking properties for propellant formulations wherein the process comprises of heating a mixture of triol and castor oil with a diisocyanate, to a temperature of 85 to 95°C for one hour, adding a polyol, heating curher for 45mins to 60mins at 90-100°C obtain ting the desired curing agent wherein triol and castor oil are taken in the ratio of 1:1 by weight and diisocyanate is taken in quantity 2 to 3 times the weight of the mixture of castor oil and triol and wherein furher triol, polyol and castor oil are in 5:8:5 equivalent weight ratio. 2. A process as claimed in calim 1 where triol is trimethylol propane having three hydroxy terminated groups. 3. A process as claimed in claim 1 wherein polyol is sorbitol having six hydroxy groups. 4. A process as claimed in claim 1 wherein castor oil has two to three hydroxy groups. 5. A process as claimed in claim 1 wherein diisocyanate is toluene diisocyanate. 6. A process for the preparation of a curing agent for propellant formulations as substantially illustrated and described herein.

Full Text

The present invention relates to an improved process for preparation of curing agent with cross-linking properties for propellant formulations.
Considerable variety of compounds have already been proposed for the purpose. Cross linking of binding agents preferably polymers to increase their stability and the life in case of propellants or such curing agents for cross linking the hydroxy-terminated polybutadiene, herein after to be named as HTPB, with urethane linkages, isocyanates, terminated compounds like toluene diisocyanate, hexamethylene diisocyanate, dimethyl diisocyanate, isophorone diisocyanate are used as cross linking agents, more particularly curing agents, in the propellant formulations.
However, with long chain polymers, particularly copolymers, more particularly block copolymers, even more particularly hydroxy terminated block copolymers, hereinafter to be named as HTBCP, these known such cross linking agents particularly curing agents as stated herein above produce cross linked products of such polymers having poor mechanical properties.
Yet another drawback of such curing agents is that the solidification of the end product, i.e. of propellants is not achieved to the desired extent for specific applications for which they are made.
Therefore, there is great need for a novel cross linking agent, more particularly a novel curing agent with improved properties to overcome such disadvantages of the known curing agents of the prior art.
Accordingly, an object of the present invention is to propose a novel curing-agent which obviates the disadvantages associated with the curing agents of the prior art.
Another object of the present invention is to propose a curing agent used for cross linking long chain polymers for better mechanical properties.
According to this invention there is provided an improved process for preparation of curing agent with cross-linking properties for propellant formulations wherein the process comprises of heating a mixture of triol and castor oil with a diisocyanate, to a temperature of 85 to 95°C for one hour, adding a polyol, heating further for 45 min to 60 min at 90-100°C obtaining the desired curing agent wherein triol and castor oil are taken in the ratio of 1:1 by weight and diisocyanate is taken in quantity 2 to 3 times the weight of the mixture of castor oil and triol and wherein further triol, polyol and castor oil are in 5:8:5 equivalent weight ratio.
According to another preferred embodiment of the present invention, triol, preferably trimethyiol propane having three hydroxy terminated groups, polyol, preferably sorbitol having essentially six hydroxy groups and castor oil, having 2 to 3 hydroxy groups and these hydroxy terminated reactors are preferably taken in the equivalent weight ratio of 5:8:5.
According to the proposed method of the present invention, a novel curing agent is provided having isocyanate 15 to 25%.

: Another object of the present invention is to
propose a curing agent used for cross linking long chain
polymers for better mechanical properties.
According to this invention there is provided a process for the preparation of a curing agent
wi»h improved cross linking properties for propellants
comprising in reacting a mixture of hydroxy terminated compounds with diisocyanate.
In accordance with the present invention, the novel curing agent is
obtained by reacting the mixtures of hydroxy terminated compounds like castor oil, triol, polyol, essentially" With diisocyanate, preferably taken in two or three times in equivalent weight proportion to the total hydroxy value of the mixture of hydroxy terminated compounds.
According to another preferred embodiment of the present invention, triol, preferably trimethylol propane having three hydroxy terminated groups, polyol, preferably sorbitol having essentially six hydroxy groups and castor oil, having 2 to 3 hydroxy groups and these hydroxy terminated reactors are preferably taken in the equivalant weight ratio of 5:0:5.
According to the proposed method of the present invention, a novel curing agent is provided having isocyanate 15 to 25%.

According to another preferred embodiment of the present invention, a novel curing agent is provided, prepared by the present method of invention, more preferably, having viscosity 1000 to 1500 at 25oC.
According to still another preferred embodiment of the present invention, a novel cross linking agent, more particularly, a curing agent is disclosed, more particularly for long chain polymers, essentially having hydroxy terminated groups which can also be used for short chain polymers, again having hydroxy terminal groups and these said novel curing agent is also applicable for all class of propellant formulations comprising essentially hydroxy terminated polymers.
The proposed method of the present invention for the synthesis of proposed novel curing agent is, the said process comprising of reaction of castor oil, & triol like trimethylol propane in 1:1 ratio with toluene diisocyanate which in turn is taken atleast 2 to 3 times equivalent weight proportion of the total hydroxyl value of mixture of the hydroxy terminated compounds like sorbitol and a triol and a polyol which however in turn are taken in ratio of 8:5:5. The said reaction is carried out in three necked round bottomed flask and fitted with the condenser and thermometer and to add the polyol during the ongoing process after one hour of the reaction time. According to the proposed method, the mixture of diisocyanate, castor oil and trimethylol propane is allowed to heat upto 100°C, preferably between 85 to 100°C for one hour to which the polyol like melted sorbitol which in turn is melted at 90°C is added and heating is allowed for another one hour at preferable temperature of 90°C. The whole synthesis is completed preferably in one hr to 2 hrs time, more preferably 1 1/2 to 2 hrs.

The invention is illustrated with the following example
which are not intended to limit the scope of the invention
and any modification, therein, is considered within the scope
of the present inventi en to yield the product for the said
purpose.
Example 1:
Weighed quantity of 45 gms of castor oil, 11 grns of
trimethylol propane and i83 grms of toluene diisocyanate are
taken in a round bottomed flask of capacity one litre kept on
a heating mantle with provision of controlling the heating.
The reaction mixture is allowed to heat upto 95°C for 60
minutes. At this stage, the melted 9 gms of sorbitol, melted
at 90°C, separately are added to the reaction vessel, i.e
three necked round bottom flask and the reaction is allowed
to continue for 4 5 minutes at temperature of 100°C. The
resulted curing agent is tested for viscosity and isocyanate
percentage obtaining viscosity 1200 cps at 25°C at 25°C and
isocyanate percentage 18%.

I CLAIM:
1. An improved process for preparation of curing agent with cross-linking properties for propellant formulations wherein the process comprises of heating a mixture of triol and castor oil with a diisocyanate, to a temperature of 85 to 95°C for one hour, adding a polyol, heating curher for 45mins to 60mins at 90-100°C obtain ting the desired curing agent wherein triol and castor oil are taken in the ratio of 1:1 by weight and diisocyanate is taken in quantity 2 to 3 times the weight of the mixture of castor oil and triol and wherein furher triol, polyol and castor oil are in 5:8:5 equivalent weight ratio.
2. A process as claimed in calim 1 where triol is trimethylol propane having three hydroxy terminated groups.
3. A process as claimed in claim 1 wherein polyol is sorbitol having six hydroxy groups.
4. A process as claimed in claim 1 wherein castor oil has two to three hydroxy groups.
5. A process as claimed in claim 1 wherein diisocyanate is toluene diisocyanate.
6. A process for the preparation of a curing agent for propellant formulations as substantially illustrated and described herein.

Documents:

20-del-1996-abstract.pdf

20-del-1996-claims.pdf

20-del-1996-complete specification (granted).pdf

20-del-1996-correspondence-others.pdf

20-del-1996-correspondence-po.pdf

20-del-1996-description (complete).pdf

20-del-1996-form-1.pdf

20-del-1996-form-2.pdf

20-del-1996-form-3.pdf

20-del-1996-form-4.pdf

20-del-1996-gpa.pdf

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Patent Number

193324

Indian Patent Application Number

20/DEL/1996

PG Journal Number

29/2004

Publication Date

17-Jul-2004

Grant Date

27-Jan-2006

Date of Filing

04-Jan-1996

Name of Patentee

CHIEF CONTROLLER, RESEARCH & DEVELOPMENT

Applicant Address

B-341, SENA BHAWAN, DHQ P.O.,NEW DELHI-110 011 INDIA

Inventors:

#	Inventor's Name	Inventor's Address
1	VENKATRAMAN KRISHNA BHAT	B-341, SENA BHAWAN, DHQ P.O.,NEW DELHI-110 011 INDIA
2	PRABHAKAR GOPAL SHROTRI	B-341, SENA BHAWAN, DHQ P.O.,NEW DELHI-110 011 INDIA
3	HARIDWAR SINGH	B-341, SENA BHAWAN, DHQ P.O.,NEW DELHI-110 011 INDIA
4	DASHARATH DAGADU GAIKWAD	B-341, SENA BHAWAN, DHQ P.O.,NEW DELHI-110 011 INDIA

PCT International Classification Number

B23P 025/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA