Title of Invention

"A PRECESS FOR THE PREPARATION OF PHASE TRANSITION MATERIAL OF LOWER HYDROCORBONS"

Abstract

A process for preparation of phase transition material of lower hydrocarbons from n-decane to n-tricosane and hydrocarbons, n-tricosane to n-heptatriacontane which comprises in the steps of dissolving separately each constituent hydrocarbon in the range of 0.02 to 3% in a solvent mixture comprising toluene, xylene and petroleum ether, preferably in a ratio of 3: 1.5:1; stirring at 800 to 1000 rpm each of the solution of (hydrocarbon +solvent mixture) preferably at a temperature of 60 to 80 °C for 1.5 to 20 mixtures; mixing together of different solutions while stirring at 60 to 80°C, subjecting the constituent solution mixture to evaporation while stirring in a gradually reducing temperature environment, cooling the constituent solution mixture while stirring the mixture at 1 to 2°C per minute while maintaining the outside temperature at 20 to 25 °C wherein cooling is carried out by placing the mixture in ice- bath at the temperature of 0°C to minus 10 °C till the solid of mixture is formed, kneading the mixture under pressure of 800 to 950 mm Hg for upto 30 to 40 minutes.

Full Text

FIELD OF INVENTION The present invention relates to a phase transition "material. More particularly, the present invention relates to phase transition material, which is an expansion mixture, used as a temperature sensing medium suitable for use in wax based thermostats. PRIOR ART The wax (phase transition material) based thermostats are devices, that open and close valve ports for controlling temperature fluctuations of process & measuring equipment's. The energising of the thermostats by means of this phase transition material, actuates the thermostats plunger, the other-end of which is connected to the critical component of the sensitive device. Thus a suitable phase transition material having consistent and high coefficient of expansion over the temperature zone of interest, is required for energising of thermostats. Waxes are of particular interest for use in thermostat valves because they expand over temperature ranges of practical significance and are both plentiful and inexpensive. Waxes are also resistant to oxidative and thermal degradation and therefore, have longer shelf-life. Moreover waxes are safe to handle and environment friendly. Commercially available waxes, like paraffin wax, micro-crystalline wax and petroleum jelly are known to have been used in wax based sensing medium for use in thermostat's. One of the drawback of above referred sensing mediums is that, they fail to provide the required expansion characteristics over the entire temperature zone. Another drawback of above referred sensing mediums is that, they could withstand only limited number of heating/cooling cycles. Yet another disadvantage of above referred sensing mediums is that they register a small and slower plunger movement during the expansion/contraction cycle of the medium, in the temperature zone of interest. Another reported wax based expansion material, is manufactured by absorption of liquid phase waxes in carbon black particles followed by its pulverisation. One of the disadvantage of above wax is that the use of carbon particles makes the manufacturing process complicated. Another reported US patent (5,971,288 October 26, 1999) utilises wax-based expansion mixture, comprising an elastomer, waxy alkanes as electrical isolators and electrical conductor particles. One of the drawback of the above expansion mixture is that it is electrically conducting and is not safe to handle. Another disadvantage of the above expansion mixture is that it has shorter shelf-life, as the elastomer used in the mixture is prone to oxidative and thermal degradation which limits the number of heating-cooling cycles. Further disadvantage of the above expansion mixture is that it results in slower movement of piston. Still further disadvantage of the above expansion mixture is that it results in longer time for valve actuation and pump operation, thereby increasing electrical consumption. This, in turn adversely affects cost-effectiveness. Yet further disadvantage of the above expansion mixture is that it uses too many constituents and involves complicated processing in the preparation of wax which adds to the increased cost. Still further disadvantage of the above expansion mixture is the inability of gelation to occur at low temperatures, so the valve may not be effective at lower temperatures. Still further disadvantage of the above expansion mixture is the lowering of efficiency of the control valve due to the lack of complete reversibility of gelation as the isolated segments may not attain the original configuration upon cooling and achieve the required characteristics upon subsequent heating. Still further disadvantage of the above expansion mixture is the difficulty of removal of wax from the cavity. OBJECTS OF THE INVENTION The primary object of the present invention is to provide an improved wax-based phase transition material and a process of synthesis, where-in the phase transition material prepared thereby, has a high coefficient of expansion for use in actuators of thermostats that operates over higher temperatures. Another object of the present invention is to provide an improved wax-based phase transition material and a process of synthesis, where-in the phase transition material prepared thereby has its phase transformation in the temperature zone of 55-72°C. Yet another object of the present invention is to provide an improved wax-based phase transition material and a process of synthesis, where-in the phase transition material prepared thereby has stable phase 'transition property. Still another object of the present invention is to provide an improved wax-based phase transition material and a process of synthesis, these of which is based on indigenous materials. Still another object of the present invention is to provide an improved wax-based phase transition material and a process of synthesis, where-in the phase transition material prepared thereby has its density, 0.87±0.1 g/cc at 30°C. Yet another object of the present invention is to provide an improved wax-based phase transition material and a process of synthesis, where-in the phase transition material prepared thereby has melting point of 58±0.2°C. Further object of the present invention is to provide an improved wax-based phase transition material and a process of synthesis, where-in the phase transition material prepared thereby has uniform expansion characteristics from 58 to 80°C. Still further object of the present invention is to provide an improved wax-based phase transition material and a process of synthesis, where-in the phase transition material prepared thereby has its volume, at least 8% higher in the liquid phase at 80°C than that at 58±0.2°C. Even further object of the present invention is to provide an improved wax-based phase transition material and a process of synthesis, where-in the phase transition material prepared thereby remains in liquid phase, without volatilisation, up to 100°C. Yet further object of the present invention is to provide an improved wax-based phase transition material and a process of synthesis, where-in the phase transition material prepared thereby % volume contraction of about 15±1% Still further object of the present invention is to provide an improved wax-based phase transition material and a process of synthesis, where-in the phase transition material prepared thereby can be tailor-made to suite other temperature zone of interest within the overall range of 45 to 85°C. Even further object of the present invention is to provide an improved wax-based phase transition material and a process of synthesis, where-in the phase transition material prepared thereby is non-hazardous. Yet further object of the present invention is to provide an improved wax-based phase transition material and a process of synthesis, where-in the phase transition material prepared thereby is environmentally friendly. Still further object of the present invention is to provide an improved wax-based phase transition material and a process of synthesis, where-in the phase transition material prepared thereby is non-corrosive. Still further object of the present invention is to provide an improved wax-based phase transition material and a process of synthesis, where-in the phase transition material prepared thereby does not undergo any oxidative degradation. Still further object of the present invention is to provide an improved wax-based phase transition material and a process of synthesis, where-in the phase transition material prepared thereby does not undergo any thermal degradation over a life cycle use. Still further object of the present invention is to provide an improved wax-based phase transition material and a process of synthesis, where-in the phase transition material prepared thereby is easy to process and safe to handle. STATEMENT OF INVENTION According to the present invention, a hydrocarbon-based synthetic wax is provided which in its simplest form comprises of paraffins:- n-tricosane, n-tetracosane, n-pentacosane, n-hexacosane, n-heptacosane, n-octacosane, n-nonacosane, n-triacontane and n-dotriacontane, n-tritriacontane, n-tetratriacontane, n-pentatriacontane, n-hexatriacontane, n-heptatriacontane, n-hentriacontane. The required properties can be introduced in the wax by varying proportion of n-alkanes and processed at optimised conditions. Additional objects, features and advantages of the present invention will become apparent to those skilled in the art, upon consideration of the following detailed description of preferred embodiments. According to this invention there is provided a process for preparation of phase transition material of lower hydrocarbons from n-decane to n-trieosane and hydrocarbons, n-tricosane to n-heptatriacontane which comprises in the steps of: i) dissolving separately each constituent hydrocarbon in a solvent mixture ii) stirring each of the solution of (hydrocarbon+solvent mixture) iii) mixing together of dillerent solutions while stirring at elevated temperature iv) subjecting the constituent solution mixture to evaporation while stirring in a gradually reducing temperature environment v) cooling the constituent solution mixture while stirring the mixture vi) kneading the mixture underpressure upto 30 to 40 minutes Commercially available paraffins as per Table I are purified by methods known in the art. Table-1 below, gives the proportions, giving the broad range and the preferred range of wt% in which each of the constituent is required to be present in the expansion mixture of the present invention, jab|e 'also shows the melting point of the individual paraffins. Table 1 ; Wax based phase transition material for use at 55-72"C (Table Removed) In the present process, the weighed amounts of hydrocarbons are dissolved separately in 120-150 ml of mixture of solvents( toluene, xylene and petroleum-ether taken in the ratio 3 : 1.5 : 1.0 ). Each (hydrocarbon+mixture of solvents) solution is mixed by stirring @ 800 to 1000 rpm at 60 to 80°C for 15 to 20 minutes. All the separate solution thus prepared, are then poured into a large petri-dish and the stirring continued for allowing the solvents to evaporate until homogeneity. The total mixture of solution in the petri-dish is then allowed to cool ai l-2°C/per minute, with stirring continued, maintaining outside temperature between 20 to-25°C. The total wax mixture is further cooled in a vat placed in an ice-bath kept at a temperature of 0°C to -10°C with constant stirring, until a solid wax mass is formed. This solid wax mass is then kneaded at a pressure of 800-950 mm Hg for 30 to 40 minutes to give resultant solid mixture. This mixture gives a volume expansion of 15±1%. The different constituents have Synergic effect on each other as can be seen from Table-I above. The melting point of constituents of the present invention varies from 50 to 77°C, while the melting point of the mixture , being 58±0.2°C and the elastic properties of this newly developed phase transition material are not present in the constituents of this material when tested separately. Also the expansion characteristic of this new material over the entire temperature zone of interest are almost linear, whereas expansion characteristics of the constituents of this material are quite steep, when tested separately. The phase transition material disclosed in the present invention will now be more particularly described by specific example. It is to be understood that the particulars embodying the invention arc disclosed by way of illustration and not as a limitation of the invention. The principal and feature of this invention may be employed in various and numerous embodiments without departing from the scope of this invention for obtaining designer characteristics in the end-product. EXAMPLE Two expansion mixtures, referred to as Example-1 and Example-2, as shown in Table-11 below, are prepared by taking constituents from the paraffin's indicated in Table-1 above and mixed in accordance with the above protocol. The resultant mixture has a melting point of 58±0.2°C, which is useful for actuation of thermostats in the temperature range of 55°C-72°C. Table-II below gives the proportion of the constituents taken for the purpose. Table 2 ; Wax based phase transition material for use at 55-72°C (inciting point 58±0.2°C) (Table Removed) The weighed amounts of hydrocarbons, are taken in the proportions as refereed to in Table-II above. Each of these hydrocarbon, than separately dissolved in 120-150 ml of mixture of solvents (toluene, xylene and petroleum-ether in the ratio 3 : 1.5 : 1.0 ). During the solutionising each of the mixture was stirred at the rate of 800 rpm, for 15 to 20 minutes while the temperature was maintained around 75±5°C. Each of these constituent solutions (hydrocarbon+mixture of solvents) are then poured into a large petri-dish. The solvents are then allowed to evaporate with constant stirring, until homogeneity while mixture is gradually allowed to cool @ 1-2°C per minute, under constant stirring. The outside temperature is lowered gradually to between 25 to 30°C. Thereafter the vat containing the mix is placed in an ice-bath at a temperature of 0°C to -10°C with constant stirring, until a solid mass was formed. The solid is then kneaded at a pressure of 800-950 mm Hg for 30 to 40 minutes to give resultant solid mixture. This mixture gives a volume expansion of 15 to 18 %. As the amount of higher hydrocarbons increases, the melting point also increases, and the expansion mixture is suitable for use in thermostats requiring waxes having higher temperature operating zones. However the percentage volume expansion of this mixture is slightly lowered, such a mixture is suitable for use in thermostat that must move the piston a shorter distance. EVALUATION OF PROPERTIES OF FORMULATED WAX MATERIAL The phase transition material produced by the present invention was subjected to various evaluation tests and the improved proprieties were confirmed which are as under: i) The density of the wax was determined by gradient column method and was 0.87±0.1 g/cc at 25°C and 0.74 at 55°C. ii) The % volume contraction was 15± 1 %. iii) The thermal curve obtained using differential scanning calorimeter (DSC), exhibited an endotherm in the range of 45 - 85°C, with the peak melting temperature at 58°C. Although the invention has been described in detail with reference to a preferred embodiment as exemplified by Example-I and Example-11 formulationsi to obtain Wax mixtures operating in varying temperature zone of interest, it is to be understood that the above description of the present invention is susceptible to considerable modifications, variations and adaptations by those skilled in the art. Such modifications are intended to be considered within the scope and spirit of the present invention, which is further set forth by following claims : WE CLAIM: 1. A process for preparation of phase transition material of lower hydrocarbons from n-decane to n-tricosane and hydrocarbons, n-tricosane to n-heptatriacontane which comprises in the steps of: I) dissolving separately each constituent hydrocarbon in the range of 0.02 to 3% in a solvent mixture comprising toluene, xylene and petroleum ether, preferably in a ratio of 3: 1.5:1; II) stirring at 800 to 1000 rpm each of the solution of (hydrocarbon +solvent mixture) preferably at a temperature of 60 to 80 °C for 15 to 20 mixtures; III) mixing together of different solutions while stirring at 60 to 80°C, IV) subjecting the constituent solution mixture to evaporation while stirring in a gradually reducing temperature environment, V) cooling the constituent solution mixture while stirring the mixture at 1 to 2°C per minute while maintaining the outside temperature at 20 to 25 °C wherein cooling is carried out by placing the mixture in ice- bath at the temperature of 0°C to minus 10 °C till the solid of mixture is formed, VI) kneading the mixture under pressure of 800 to 950 mm Hg for upto 30 to 40 minutes. 2. The process as claimed in claim 1 wherein the said lower paraffins are present in preferably 0,02 to 3% more preferably from 0.1 to 1.5% by weight of the phase transition material. 3. The process as claimed in claim 1 wherein n-tetracosane is present in preferably from 0.1 to 5.0% more preferably from 1.0 to 3.0%) by weight of the phase transition material. 4. The process as claimed claim 1 wherein n-pantacosane is present in preferably from 1.0 to 6.0% more preferably from 3.0 to 5.2% by weight of the phase transition material. 5. The process as claimed in claim 1 wherein n-hexacosane is present in preferably from 2.0 to 10%, more preferably from 5.0 to 8.0% by weight of the phase transition material. 6. The process as claimed in claim 1 wherein n-heptacosane is present in preferably from?.5 to 13.0%, more preferably from 9.2 to 11.8% by weight of the phase transition material. 7. The process as claimed in claim 1 wherein n-octacosane is present in preferably from 10.0 to 15.0% more preferably from 10.5 to 12.2% by weight of the phase transition material. 8. The process as claimed in claim 1 wherein n-nonacosane is present in preferably from 10.0 to 16.0% more preferably from 11.0 to 13.0% by weight of the phase transition material. 9. The process as claimed in claim 1 wherein n-triacotane is present in preferably from 10.0 to 15.0, more preferably from 10.5 to 12.0 by weight of the phase transition material. 10. The process as claimed in claim 1 wherein n-hentriacotane is present in preferably from 9.0 to 15.5%, more preferably from 11.0 to 12.8% by weight of the phase transition material. 11. The process as claimed in claim 1 wherein n-dotriacotane is present in preferably from 6.0 to 10.8% more preferably from 7.8 to 10.1% by weight of the phase transition material. 12. The process as claimed in claim 1 wherein n-tritraicontane is present in preferably from 5.0 to 10.8%, more preferably from 7.5 to 9.3% by weight of the phase transition material. 13. The process as claimed in claim 1 wherein n-tetratriacontane is present in preferably from 0.5 to 5.5%, more preferably from 3.8 to 5.5% by weight of the phase transition material. 14. The process as claimed in claim 1 wherein n- pentatriacontane is present in preferably from 0.2 to 4.8%, more preferably from 1.0 to 3.0% by weight of the phase transition material. 15. The process as claimed in claim 1 wherein n-hexatriacontane is present in preferably from 0.1 to 3.5%, more preferably from 0.9 to 2.3% by weight of the phase transition material. 16. The process as claimed in claim 1 wherein n- heptatriacontanc is present in preferably from 0.1 to 3.0%, more preferably from 0.1 to 2.0% by weight of the phase transition material. 17. The process for preparation of phase transition material of lower hydrocarbons from n-decane to n-tricosane and hydrocarbons, n-tricosane to n-heptatriacontane substantially as herein described.

Documents:

1130-del-2000-abstract.pdf

1130-del-2000-claims.pdf

1130-del-2000-correspondence-others.pdf

1130-del-2000-correspondence-po.pdf

1130-del-2000-description (complete).pdf

1130-del-2000-form-1.pdf

1130-del-2000-form-19.pdf

1130-del-2000-form-2.pdf

1130-del-2000-form-3.pdf

1130-del-2000-form-4.pdf

1130-del-2000-gpa.pdf