Title of Invention

PROCESS FOR PREPARATION OF TRANSPARENT INORGANIC ZRO(OH) 5H2O POLYMER DOPED WITH ADDITIVES

Abstract

A transparent ZrO(OH)25H2O polymer doped with additives selected from inorganic, organic additives and having a transparency of 65 to 90 % and stable at room temperature and the process for preparing the same. The process comprises providing a solution of additives selected from inorganic, organic additives for doping and mixing with solution of aqueous ZrOC12 8H2O in water; hydrolysis and precipitation; polymerization and finally drying at room temperature.

Full Text

1 Field of Invention: The present invention relates to a stable transparent inorganic polymer of ZrO(OH)25H2O doped with additives selected from inorganic and organic additives stable at least at room temperature and its process of manufacture. Such transparent polymers are suitable for inkjet labeling, coating, pigments, biomaterials, and processing of metastable ZrO2 ceramic derivatives for fabricating small devices and components in a specific shape. Background and Prior art: An inorganic polymer of ZrO(OH)2 ^jitHfeO is an important material for inkjet labeling, coating, colorless pigments, and biomaterials. Furthermore, it is an important precursor for processing of metastable Z1O2 ceramics and components for structural and electronic applications (US patent 20020172838 Al, US patent 20020031675 Al, US patent 20020086153 Al). A small addition of transition metal cations adds useful colour for colour pigments and other applications. A common method to synthesize ZrO(OH)2 x H2O in form of a gel is the sol-gel chemistry. It uses a zirconium alkoxide, for example, zirconium isopropoxide Zr(i-OC3H7)4, zirconium propoxide Zr(n-OC2Hy)4, or zirconium butoxide Zr(n-OC4Hg)4 to promote and support the gelation process in an amorphous polymer structure. One of the major disadvantages with this method is that it is carried out in a nonaqueous solution. Both of the starting chemicals of nonaqueous solvent and the alkoxide are expensive, toxic and add significantly to the cost of the final product. Moreover, it never gives a stable transparent bulk amorphous gel. It degrades to hydrated zirconia, ZrO2 x H2O, in ambient atmosphere at room temperature. Hence, a need remains for a low cost manufacturing of a transparent ZrO(OH)2 x H2O gel or glass, which stands to be stable at room temperature or so for the above applications. It can be resolved with an efficient reactive doping with a small amount of Al3+, R3+ rare-earth cations and/or a water-soluble polymer with a simple hydrolysis reaction in water at controlled temperature. Objects of Invention Thus the basic object of the present invention to provide a transparent ZrO(OH)25H2O polymer doped with inorganic and organic additives with transparency in the range of 65 to 95 %. A further object to provide a transparent ZrO(OH)25H2O polymer doped with inorganic and organic additives which is stable at least at room temperature. Another object of the present invention is to provide a process for manufacturing a transparent and stable ZrO.(OH)25H2O polymer doped with inorganic and organic additives. A further object is to provide, a very convenient, simple and economic process for manufacturing a transparent and stable ZrO(OH)25H2O polymer doped with inorganic and organic additives compared to the conventional sol-gel method to obtain a similar inorganic polymer.... A further object is to provide process for manufacturing a transparent and stable ZrO(OH)25H2O polymer doped with inorganic and organic additives such that the final product is obtained in a fewer steps. Another object is to provide a process for manufacturing a transparent and stable ZrO(OH)25H2O polymer doped with inorganic and organic additives such that the process deals with reaction in water, which is one of the cheapest solvents and available easily in plenty of amounts, and overall it is nontoxic in nature. Summary of Invention Thus according to one aspect of the present invention there is provided a transparent ZrO(OH)25H2O polymer doped with additives selected from inorganic, organic additives and having a transparency of 65 to 95%. 3 According to another aspect of the present invention there is provided a process for preparation of a transparent ZrO(OH)2.5H2O polymer doped with additives selected from inorganic, organic additives and having a transparency of 65 % to 95% comprising steps of: (i) providing a solution of said doping additives in an aqueous solution of ZrOCl2 SH2O (ii) Hydrolysis in the solution provided in step (i) and precipitation of the hydrolized product; (iii) Polymerization of the product obtained at step (ii) to form monolithic ZrO(OH)2 5H2O doped polymer; (iv) drying the doped polymer formed as step (iii) at room temperature. Schematic representation of formation of a stable ZrO(OH)2 5H2O polymer doped with additives. The scheme below summarizes the formation of ZrO(OH)? 5H2O in form of a transparent inorganic polymer by hydrolysis and polycondensation of ZrOCl2 8H2O in solution mixed with the AICI3 6H2O, RCI3 6H2O, PVA, or PVP at 1 to 5°C controlled temperatures. The two solutions,of ZrOCl2-SH2O and AICI3 6H2O, RClj 6H2O, PVA, or PVP are mixed together in a predetermined ratio by stirring at I to 5°C in a water bath of Julabo Model HD-4. Then cold NH4OH is added in steps to induce the hydrolysis of the metal cations in a controlled manner at this temperature by stirring the total mixture. Hydrolysis of the two types of the metal cations occurs in-situ as soon as adding NH4OH. A white co-precipitate results in a product of the mixed metal oxyhydroxides. At intermediate stage of the reaction, the precipitates are not thermodynamically stable in an equilibrium configuration with solution. As a result, they start dissolving in the solution after a certain period of the reaction. It occurs by a regular increase in viscosity of solution as a function of time until a clear transparent gel appears on dissolved precipitate. It takes 20 to 30 min to get a clear transparent inorganic polymer at an average 3.5 pH as per the concentration. The obtained polymer gel is dispersed and washed in distilled water (to remove the byproduct impurities of NHd+ and Cl* ions), filtered and then dispersed in cold water again at 1 to 5°C, where in it polymerizes in ;i specific shape in a mold. 4 A translucent solid polymer appears of ZrO(OH)25H2O on evaporating the excess water at room temperature. It is observed that the process of the polymerization is promoted effectively in presence of the inorganic additives of Al3+ or R3+ cations as well as the organic PVA or PVP polymer molecules. As analyzed by X-ray diffraction and thermal and thermogravimetric analysis, a substantially stable amorphous, polymer ZrO(OH)25H2O structure thus appears in combination with the additives. Schematic representation of formation of a stable ZrO(OH)25H2O polymer doped with additives 5 Detailed Description of Invention The transparent ZrO(OH)2 5H;jO polymer doped with additives of the present invention is stable at least at room temperature and the process leading to production of the same is simple and cost effective unlike.that of the prior art. The inorganic additive for doping the said transparent ZrO(OH)25H2O polymer is selected from Al3+, La3+, Eu3+, Gd3+, Tb3+ or Dy3+ and other rare earth cations. The amount of such additives are in the range of 0.2 to 10 mol %, preferably 0.2 to 5 mo] % The concentration of the said additive is 0.2 to 1.0, preferably 0.2 to 0.5 M in solution. The organic additive'for doping the said transparent ZrO(OH)25H2O polymer is selected from PVA, PVP in an amount of 1 to 10 % by weight, preferably 2 to 5 % by weight The concentration of the said additive is 2 to 4, preferably 1 to 2 g/dl in solution . The said transparent ZrO(OH)25H20polymer doped with additives can have stability of '50 to 200°C, preferably 50 to 100°C. The said transparent ZrO(OH)25H2O polymer doped with Al+3 decomposes to Z1O2 at temperature of 100 to 250°C while that doped with either LaJ\ Eu3+, Gd3\ Tb'1+ or Dyu decomposes to Z1O2 at temperature of above 100°C. While the said transparent ZrO(OH)25H2O polymer doped with PVA or PVP decomposes to ZO2 at temperature of 200 to. 400, preferably 400°C. Also the said transparent ZrO(OH)25H2O polymer doped with AI+3 and PVA decomposes to ZrO2 at temperature of 200 to 400, -preferably 400°C. According to a further aspect of the present invention there is provided a process for preparation of the said doped transparent ZrO(OH)25H2O polymer. The inorganic additive used for doping the said transparent ZrO(OH)25H2O polymer is selected from A1J\ La1'. Eu'1+, Gd3+, Tb3+ or Dy3+ and other rare earth cations. The amount of such additives used are in the range of 0.2 to 10 mol %, preferably 0.2 to 5 mol %. The concentration of the 6 said additive is 0.2 to 1.0, preferably 0.2 to 0.5 M in solution. The organic additive used for doping the said transparent ZrO(OH)25H2O polymer is selected from PVA, PVP in an amount of 1 to 10 % by weight, preferably 2 to 5 % by weight The concentration of the said additive is 2 to 4; preferably 1 to 2 g/dl in solution. In the process of the present invention the concentration of aqueous ZrOCb 8H2O used for the step of hydrolysis is from 0.2 to 2 M, preferably 0.5 to 1 M and the said step of hydrolysis is carried on at a temperature of 0 to 25°C preferably l-5°C. This results in formation of a co-precipitate. The hydrolysis and precipitation is carried out in presence of 5 to 50 %, preferably 28 % solution of cold NH4OH. For polymerization, the co-precipitate is dissolved in the said solution at a pH of 3 to 4, preferably 3.5 with a continuous increase in viscosity of the solution until a clear transparent mass of the polymer occurs. It is then washed in distilled water and dried to obtain the transparent ZrO(OH)25H2O polymer doped with additives which is stable at least at room temperature. The invention will now be discussed with reference to illustrative non limiting examples. Example-l : This example is carried out to prepare a pure compound of ZrO(OH)25H2O in water. The reaction of hydrolysis is done by adding cold NH4OH (28 %) dropwise to an aqueous ZrOCb 8H2O solution (0.5 to 1.0 M concentration) at 1 to 5°C temperatures by stirring the mixture with a magnetic stirrer. A white precipitate occurs in a hydrolyzed product of ZrO(OH)25H2O, which is dispersed in the solution. After the reaction, the precipitate was filtered and washed in distilled water, and then dispersed in cold water to polymerize in a specific shape of thin plates in a plastic mold. A monolithic ZrOfOH^SI-bO polymer gel is obtained in this way. It is not so stable and turns to be translucent on drying ;il room temperature. As analyzed by thermogravimetric (TG) analysis, a freshly prepared ZrO(OH)25H2O polymer decomposes to ZrO25H2O at temperature as low as 30 to 50°C in air. 7 Example-2 : The reaction in example-1 is repeated with doping using 1 mol % additive of AlCb 6H2O, 0.2 to 0.5 M concentration in water, lo the ZrOCb1 SH2O solution and then adding NH4OH at 1 to 5°C temperatures in a total of 250 ml batch of solution. A white coprecipilale occurs in a hydrolyzed product of metal cations on adding the NH4OH. It was observed that after a certain period of the reaction the precipitate dissolves in the solution with a continuous increase in viscosity of the solution until a clear transparent homogenized viscous mass appears. It took about 20 to 30 min to get a clear transparent polymer at - 3.5 pH at this temperature. The recovered sample (after washing in distilled water) dried in a rather stable transparent polymer gel at room temperature. The exemplary process in accordance with the invention is extended with 0.2, 2.0 and 5.0 mol % additives of AI3+ during the primary hydrolysis reaction with NH4OH. The Al3+ additives promote an extended stability of the final inorganic polymer product with Zrd+ and Al3+ two types of metal cations so that its transparent structure retains to temperature "as high as-200°C (in 5.0 mol % Al3+) in air, with no significant loss in mass, A product of Al3+ stabilized t-ZrC>2 occurs on heating over higher temperatures but below 1000°C, ExampIe-3 : Several other batches of the reactions were carried out by varying the additives of the rare-earth cations of La3+, Eu3+, Gd3\ Tb3\ or Dy3+. Their contents were varied in the 0.2 to 5 mol % range in order to achieve a maximum stability of the substituted polymer at a minimal content of the additive. It was found that all of them support a transparent structure of the inorganic polymer of an extended thermal stability. In this range of the R3+-substitution, larger the additive larger is the thermal stability of the substituted polymer. According to it, the polymerization occurs the best with an average concentration of precursor solution in the 0.2 lo 1.0 M range and at 3 to 4 pH. s Examplc-4 : A further development in example-2 or 3 was made in fabrication of transparent ZrO(OH)25H20 polymer composites with an additive of organic polymer of PVA or PVP. Its content was varied from 2 to 5 wt % to optimize it to stabilize the composite structure -by as small value as possible. The reaction is carried out with a mixed solution of ZrOCb 8H2O and PVA or PVP in water as described above. According to it, a batch of 250 ml of solution,is taken in predetermined concentrations of 0.5 to 1.0 M for ZrOCb 8H2O and 2.0 to 4.0 g/dl for PVA or PVP at 1 to 5°C temperatures and stirred for 30 min. The volume in PVA or PVP solution was taken such that it added 2 to 5 % mass in the total precursor. Adding cold NH4OH dropwise at 1 to 5°C temperatures by stirring the total solution does the desired hydrolysis reaction. The sample recovered after the reaction followed by polycondensation in water, after washing in distilled water, was dried at room temperature. It yielded a substantially stable polymer composite. It stands as such with no significant loss in mass to temperature as high as 50 to 200°C in air as per the PVA or PVP content. Example-5 : The reaction in example-4 was repeated to incorporate Al** or R'* inorganic additives along with the PVA or PVP in a composite structure. The reaction was done in a similar manner with a mixed solution in the two metal salts and the PVA or PVP polymer molecules by adding cold NH4OH dropwise at 1 to 5°C temperatures by stirring the solution. The recovered sample after the reaction and polycondensation, after washing in distilled water, is dried at room temperature. It yielded a stable polymer composite of manifested stability of the virgin inorganic polymer. The details of thermal stabilities of the inorganic polymers developed in accordance with the invention (examples 1 to 5) are given in Table 1. 9 Table 1. Stability and decomposition in modified ZrO{OH)25HiO polymers with inorganic and organic additives during the polymer reaction. The final temperature of stability or decomposition depends on the content -of the additives, Amongst all the additives explored here, the AIJ+ appears to be the most effective to retain a stable polymer structure of the final product over an extended range of temperature to as large as 200°C at content as small as 5.0 mo! %. Thus the process of the present invention is a very convenient, simple and economic when compared with the conventional sol-gel method to obtain a similar inorganic polymer. Moreover the final product is obtained in a-fewer, steps. The process deals with reaction in water, which is one of the cheapest solvents and available easily in plenty of amounts, and overall it is nontoxic in nature. The process has several other applications of synthesizing modified organic polymers with nielal cations and derivatives. 10 We claim: 1. A process for preparation of a transparent ZrO(OH)2.5H2O polymer doped with additives selected from inorganic, organic additives and having a transparency of 65 % to 95% comprising steps of: (i) providing a solution of said doping additives in an aqueous solution of ZrOCl2-8H2O (ii) Hydrolysis of the solution provided in step (i) and precipitation of the hydrolized product; (iii) Polymerization in the product obtained at step (ii) to form monolithic ZrO(OH)2.5H2O doped polymer; (iv) drying the doped polymer formed as step (iii) at room temperature. 2. A process as claimed in claim 1 wherein solution of inorganic additive provided is selected from solutions of Al3+, La3*, Eu3+, Gd3*, Tb3* or Dy3> and other rare earth cations. 3. A process as claimed in claim 2 wherein the amount of inorganic additive provided is 0.2 to 10 mol %, preferably 0.2-5 mol %. 4. A process as claimed in claim 2 wherein concentration of inorganic additive provided is 0.2 to 1.0 M, preferably 0.2 to 0.5 M in solution. 5. A process as claimed in claim 2 wherein solution of organic additive provided is selected from solutions of PVA, PVP. 6. A process as claimed in claim 5 wherein amount of organic additive provided is 1 to 10 weight %, preferably 2-5 weight %. 7. A process as claimed in claim 5 wherein concentration of organic additive provided is 2 to 4 g/dl, preferably 1 to 2 g/dl in solution. 8. A process as claimed in claim 1 wherein the concentration of aqueous ZrOCl2-8H2O used is from 0.2 to 2 M, preferably 0.5-1 M. 11 9. A process as claimed in any one of claims 1 to 8 wherein the hydrolysis is carried on at a temperature of 0 to 25°C preferably 1-5DC. 10. A process as claimed in any one of claims 1 to 9 wherein said step of hydrolysis and precipitation is carried out in presence of NH4OH. 11.A process as claimed in any one of claims 1 to 10 wherein the NH4OH used is. 5 to 50 %, preferably 28 %. 12. A process as claimed in any one of claims 1 to 11 wherein the hydrolysis and precipitation includes formation of a co-precipitate. 13.A process as claimed in claims 1 to 12 wherein polymerization %-^j is allowed to take place on dissolving the co-precipitate in the said solution with NH4OH at a pH of 3 to 4, preferably 3.5. 14.A process for preparation of transparent ZrO(OH)2'5H2O polymer doped with additives selected from inorganic, organic additives and having a transparency of 65 to 95% substantially as herein described and illustrated with-reference to the Examples 1-5, A transparent ZrO(OH)25H2O polymer doped with additives selected from inorganic, organic additives and having a transparency of 65 to 90 % and stable at room temperature and the process for preparing the same. The process comprises providing a solution of additives selected from inorganic, organic additives for doping and mixing with solution of aqueous ZrOC12 8H2O in water; hydrolysis and precipitation; polymerization and finally drying at room temperature.

Documents:

00254-kol-2003 abstract.pdf

00254-kol-2003 claims.pdf

00254-kol-2003 correspondence.pdf

00254-kol-2003 description(complete).pdf

00254-kol-2003 form-1.pdf

00254-kol-2003 form-18.pdf

00254-kol-2003 form-2.pdf

00254-kol-2003 form-3.pdf

00254-kol-2003 letters patent.pdf

00254-kol-2003 p.a.pdf

00254-kol-2003 reply f.e.r.pdf

254-KOL-2003-FORM-27.pdf