Title of Invention

'PROCESS FOR THE PREPARATION OF AN INORGANIC HIGH TEMPERATURE RESISTANT SEALANT'

Abstract

This invention relates to the process for the preparation of an inorganic high temperature resistant sealant comprising of the steps of preparing a mixture comprising 20 to 40% by wt. of each of alumina and zinc oxide, 5 to 20% of magnesium oxide, 20 to 30% of aqueous solution of sodium silicate or potassium silicate; taking the mixture in a reaction vessel and homogenising the mixture by stirring at the speed of 250 to 300 rpm; allowing the reaction to take place for a period of 4 to 8 hours; the PH of the sealant varies from 9.5 to 12.

Full Text

A PROCESS FOR PREPARATION OF HIGH TEMPERATURE RESISTANT SEALANT This invention relates to a process for preparation of inorganic high temperature resistant sealant. High temperature resistant sealants perform three basic functions namely to fill the space so as to create a seal, to form an impervious barrier to fluid flow, and! to maintain the seal at high temperature. These sealants bind two similar or dissimilar surfaces together by adhering strongly to both the surfaces even at high temperatures. Sealants are required to be inert, and thermally stable at elevated temperatures. Requirements of high temperature sealant exist for laser and electronic fields wherein the temperature encountered may be over 800°C extending to around 1400° C. The sealants known in the art, use organic materials such as vinyl polymers,, rubber derivatives, asphalt, waxes, resin, cellulose nitrate, aliphatic and aromatic solvents, plasticisers etc. The disadvantage of the above-mentioned sealants is that they loose their property of adhesion or sealing at temperatures over 300°C. These sealants are therefore destroyed when used in laser or electronic applications where as mentioned above the temperature may be over 800°C extending to 1400°C. The primary object of the present invention to propose a process for the preparation of an inorganic high temperature resistant sealant . Another object of the present invention is to propose a process for the preparation of an inorganic high temperature resistant sealant which can withstand high temperature around 1600°C and also simultaneously a high pressure of 4-6 atmospheres. Still another object of the present invention is to propose a process for the preparation of an inorganic high Temperature resistant sealant which uses optimum reaction parameters like reaction period, temperature and proper proportions of sodium silicate/potassium silicate, alumina, zinc oxide, magnesium oxide which lead to higher yield. Further object of the present invention is propose a process for preparation of an inorganic high temperature resistant sealant which is capable of adhering metal to ceramic, and ceramic to ceramic. Yet further object of the present invention is to propose a process for preparation of an inorganic high temperature resistant sealant which is cheap, simple and can be adopted on small scale. Still further object of the present invention is to propose a process for preparation of an inorganic high temperature resistant sealant which uses non-toxic, high-temperature resisting oxides like alumina, silica, zinc oxide etc. Yet further another object of the present invention is to propose a process for preparation of an inorganic high temperature resistant sealant which uses water as solvent leading to aqueous based sealant making the sealant free from fire hazards. These and other objects will be apparent from the following detailed description and specific example which is intended to be typical of rather than in anyway limiting on the scope of the present invention. According to this invention a process for the preparation of an inorganic high temperature resistant sealant composition comprising of 20 to 40% by wt. each of alumina and zinc oxide, 5 to 20% of magnesium oxide and 20 to 30% of aqueous solution of sodium or potassium silicate. According to this invention, there is provided a process for preparation of an inorganic high temperature resistant sealant, comprising of the steps:- a) preparing a mixture comprising 20 to 40% by wt. of each of alumina and zinc oxide, 5 to 20% of magnesium oxide, 20 to 30% of aqueous solution of sodium silicate or potassium silicate; b) taking the mixture in a reaction vessel and homogenising the mixture by stirring at the speed of 250 to 300 rpm; c) allowing the reaction to take place for a period of 4 to 8 hours. d) the PH of the sealant varies from 9.5 to 12. The invention will now be illustrated but not limited by the following examples:-Example 1;- A reaction vessel fitted with thermometer, dropping funnel and electric stirrer is charged with 0.2 to 0.5 mole of Alumina, 0.1 to 0.4 mole of Zinc Oxide, 0.05 to 0.2 mole of Magnesium Oxide, 2 to 20 ml of Sodium Silicate (SS). The reaction temperature is kept at 30 degree celcius. The stirring speed is maintained at 250- 300 rpm. The reaction is allowed to continue for 4 to 8 hours. A colourless sealant paste is obtained. Example 2:- The reaction vessel is charged with 0.2 to 0.5 mole of Alumina, 0.1 to 0.4 mole of Zinc Oxide, 0.05 to 0.2 mole of Magnesium Oxide and 2 to 20ml of Potassium Silicate (PSB). The reaction is carried out as in example 1. Example 3:- The reaction vessel is charged with Alumina (0.2 to (0.1) mole), Zinc Oxide (0.1 to 0.4 mole), Magnesium Oxide (O.l) to 0.2 mole), Potassium Silicate (PSA) (2 to 20 ml). Ml reaction is carried out as illustrated in example 1. It is to be understood that the process of the above description of the present invention is susceptible t considerable modifications, change and adaptation by thos skilled in the art. Such modifications are intended to be considered within the scope of the present invention, which is set forth by the following claims. I CLAIM 1. The process for the preparation of an inorganic high temperature resistant sealant as claimed in claim 1, comprising of the steps of :- a) preparing a mixture comprising 20 to 40% by wt. of each of alumina and zinc oxide, 5 to 20% of magnesium oxide, 20 to 30% of aqueous solution of sodium silicate or potassium silicate; b) taking the mixture in a reaction vessel and homogenising the mixture by stirring at the speed of 250 to 300 rpm; c) allowing the reaction to take place for a period of 4 to 8 hours; d) the PH of the sealant varies from 9.5 to 12; 2. A process for the preparation of an inorganic high temperature resistant sealant as claimed in claim 1 comprising 30 to 40% each of zinc oxide and alumina. 3. A process for the preparation of an inorganic high temperature resistant sealant prepared by the process substantially as here in described and illustrated.

Documents:

235-del-1997-abstract.pdf

235-del-1997-claims.pdf

235-DEL-1997-Correspondence Others-(24-06-2011).pdf

235-del-1997-correspondence-others.pdf

235-del-1997-correspondence-po.pdf

235-del-1997-description (complete).pdf

235-del-1997-form-1.pdf

235-del-1997-form-13.pdf

235-del-1997-form-19.pdf

235-del-1997-form-2.pdf

235-del-1997-form-3.pdf

235-DEL-1997-GPA-(24-06-2011).pdf

235-del-1997-gpa.pdf