Title of Invention	A RUBBER LATEX NANOCOMPOSITE AND A METHOD OF MAKING THEREOF
Abstract	A rubber latex nanocomposite comprising of natural rubber latex preserved in ammonia, an aqueous dispersion of layered clay having high interlayer distance, zinc diethyl dithiocarbomate, anti-oxidant styrenated phenol and a metal oxide.

Full Text

VULCANIZED NATURAL RUBBER LATEX NANOCOMPOSITES WITH SUPERIOR MECHANICAL PROPERTIES FIELD OF THE INVENTION The present invention relates to vulcanized natural rubber latex and particularly to vulcanized natural rubber latex nanocomposites with superior mechanical properties. BACKGROUND OF THE INVENTION Natural rubber (NR) is used in a variety of applications both in its liquid (latex) and solid form. Natural rubber is used for the production of several thousands of articles, including automobile tyres, hand gloves, conveyor belts etc. It also finds wide application in the health care segment like, gloves, cardiac catheters, disposable gas masks and linings etc. However, natural rubber has poor air permeability, poor solvent resistance and low modulus. Because of these disadvantages natural rubber is being replaced with synthetic rubbers like butyl rubber. But, synthetic rubber is at once expensive and an environmental hazard. Therefore, it becomes an imperative to develop a new material from natural rubber that is economic and environment friendly. The present invention addresses these and other disadvantages of the state of art. OBJECTS OF THE INVENTION This invention relates to a novel vulcanized natural rubber latex nanocomposite with superior mechanical properties. The main object of the invention is to improve the properties of natural rubber. It is an important object of the invention to increase the modulus of elasticity of natural rubber. It is another important object of the invention to increase the storage modulus of the natural rubber. It is yet another important object of the invention to decrease the air permeability of natural rubber. It is an important object of the invention to develop a natural rubber polymer that is inexpensive and environment friendly. SUMMARY OF THE INVENTION Accordingly, towards achieving the stated objectives and overcoming the disadvantages of the prior art, a rubber latex nanocomposite comprising of natural rubber latex preserved in ammonia, an aqueous dispersion of layered clay having high interlayer distance, zinc diethyl dithiocarbomate, anti-oxidant styrenated phenol and a metal oxide is herein described. In another preferred embodiment of the present invention, a method of making a rubber latex nanocomposite comprising the steps of: a. preparing aqueous dispersions of layered clay by mixing the layered clay with water and stirring the mixture continuously for at least 2 hours at a temperature of about 10°C- 50° C; b. treating ammonia preserved latex with the said aqueous dispersion of layered clay and metal oxide; c. maturing the said mixture; and d. vulcanizing the dry mixture at a temperature of about 10° C-1000 C. is herein described. BRIEF DESCRIPTION OF THE DRAWINGS Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings in which: Figure 1 shows modulus of NR nanocomposites with different layered silicates. Figure 2 shows Storage modulus of NR nanocomposites with different layered silicates. Figure 3 shows air permeabilities of NR nanocomposites with different layered silicates. While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims. DETAILED DESCRIPTION OF THE INVENTION Aqueous dispersions (10%) of layered silicates were prepared by mixing the layered silicates with required amount of water and the contents were continuously stirred for 4 hrs at room temperature. Centrifuged, ammonia preserved latex was mixed with the compounding ingredients according to the formulation given in Table 2 and stirred for half an hour for a homogeneous mixture. The compounded latex is then matured (keeping overnight to facilitate the diffusion of added chemicals) which ensures latex film to filtering through a sieve. The mixture is then castled on raised glass plates having a dimension of 13cm x 10cm x 2 mm. The casting was then allowed to dry in air till it becomes transparent and then vulcanized at 70°C for 4 hrs in an air circulated oven. It will be shown by way of examples that the modulus of the nanocomposites produced using the above method has increased 2 to 3 fold (Figure 1) and the storage modulus was increased abruptly (Figure 2). The air permeability was also reduced considerably (30 to 40 times reduction)(Figure 3). Example 1 Aqueous dispersions (10%) of layered Na-fluorohectorite were prepared by mixing the layered Na-fluorohectorite with required amount of water and the contents were continuously stirred for 4 hrs at room temperature. Centrifuged, ammonia preserved latex was mixed with the compounding ingredients according to the formulation given in Table 2 and stirred for half an hour for a homogeneous mixture. The compounded latex is then matured (keeping overnight to facilitate the diffusion of added chemicals) which ensures latex film to filtering through a sieve is then castled on raised glass plates having a dimension of 13cm x 10cm x 2 mm. The casting was then allowed to dry in air till becomes transparent and then vulcanized at 70°C for 4 hrs in an air circulated oven. The vulcanized samples thus obtained were subjected to mechanical testing. Example 2 Aqueous dispersions (10%) of layered Na-bentonite were prepared by mixing the layered Na-bentonite with required amount of water and the contents were continuously stirred for 4 hrs at room temperature. Centrifuged, ammonia preserved latex was mixed with the compounding ingredients according to the formulation given in Table 2 and stirred for half an hour for a homogeneous mixture. The compounded latex is then matured (keeping overnight to facilitate the diffusion of added chemicals) which ensures latex film to filtering through a sieve is then castled on raised glass plates having a dimension of 13cm x 10cm x 2 mm. The casting was then allowed to dry in air till becomes transparent and then vulcanized at 70°C for 4 hrs in an air circulated oven. The vulcanized samples thus obtained were subjected to mechanical testing. Example 3 Aqueous dispersions (10%) of non-layered Kaolin were prepared by mixing the non-layered Na-bentonite with required amount of water and the contents were continuously stirred for 4 hrs at room temperature. Centrifuged, ammonia preserved latex was mixed with the compounding ingredients according to the formulation given in Table 2 and stirred for half an hour for a homogeneous mixture. The compounded latex is then matured (keeping overnight to facilitate the diffusion of added chemicals) which ensures latex film to filtering through a sieve is then castled on raised glass plates having a dimension of 13cm x 10cm x 2 mm. The casting was then allowed to dry in air till becomes transparent and then vulcanized at 70°C for 4 hrs in an air circulated oven. The vulcanized samples thus obtained were subjected to mechanical testing. In all the examples the amount of filler (silicates) was kept at 10 parts per hundred rubber. The modulus, dynamic mechanical properties and the barrier properties of the material are given respectively in Figures 1, 2 and 3. We Claim, 1. A rubber latex nanocomposite comprising of natural rubber latex preserved in ammonia, an aqueous dispersion of layered clay having high interlayer distance, zinc diethyl dithiocarbomate, anti-oxidant styrenated phenol and a metal oxide. 2. A rubber latex nanocomposite as claimed in claim 1 wherein, the said layered clay dispersion includes silicates, modified layered silicates such as Na-fluorohectorite, Na-bentonite etc. 3. A rubber latex nanocomposite as claimed in claim 1 wherein, the said metal oxide may be zinc oxide. 4. A method of making a rubber latex nanocomposite comprising the steps of: a. preparing aqueous dispersions of layered clay by mixing the layered clay with water and stirring the mixture continuously for at least 2 hours at a temperature of about 10°C- 50° C; b. treating ammonia preserved latex with the said aqueous dispersion of layered clay and metal oxide; c. maturing the said mixture; and d. vulcanizing the dry mixture at a temperature of about 10° C-100° C. 5. A method of making a rubber latex nanocomposite as claimed in claim 3 wherein, the said layered clay dispersion includes silicates, modified layered silicates such as Na-fluorohectorite, Na-bentonite etc. 6. A method of making a rubber latex nanocomposite as claimed in claim 3 wherein, the said metal oxide may be zinc oxide. 7. A rubber latex nanocomposite as herein described substantially in the accompanying description and drawings. 8. A method of making rubber latex nanocomposite as herein described substantially in the accompanying description and drawings. Dated this the 8th day of May 2006

Documents:

0562-che-2005-abstract.pdf

0562-che-2005-claims.pdf

0562-che-2005-correspondnece-others.pdf

0562-che-2005-description(complete).pdf

0562-che-2005-description(provisional).pdf

0562-che-2005-drawings.pdf

0562-che-2005-form 1.pdf

0562-che-2005-form 3.pdf

0562-che-2005-form 5.pdf

562-che-2005 correspondence others 03-06-2011.pdf

562-CHE-2005 CORRESPONDENCE OTHERS 28-10-2011.pdf

562-che-2005 power of attorney 03-06-2011.pdf

562-CHE-2005 AMENDED PAGES OF SPECIFICATION 18-09-2012.pdf

562-CHE-2005 AMENDED CLAIMS 18-09-2012.pdf

562-CHE-2005 EXAMINATION REPORT REPLY RECEIVED 18-09-2012.pdf

562-CHE-2005 EXAMINATION REPORT REPLY RECEIVED 21-09-2012.pdf

562-CHE-2005 FORM-1 18-09-2012.pdf

562-CHE-2005 FORM-3 18-09-2012.pdf

562-CHE-2005 CORRESPONDENCE OTHERS 03-09-2012.pdf