Title of Invention

A METHOD FOR THE MANUFACTURE OF AQUEOUS SOLUTION OF METAL COMPLEXES AND A METHOD OF MANUFACTURING HIGH TEMPERATURE COLOURED VITREOUS GLASS-CERAMIC TILES

Abstract Disclosed herein is a method for the manufactunng of aqueous solutions of metal complexes comprising the step of adding the selected metal compound to a solution of one or more organic acids; heating the mixture formed to near boiling temperatures wherein redox reactions take place to form stable complexes with the organic complexing agents, removing the complex so formed by conventional methods. The said solution is suitable for use as a colouring formulation for vitrified glass-ceramic tiles, for obtaining excellent shades. There is also described a method of manufacturing high temperature coloured vitreous glass-ceramic tiles using aqueous solutions of metal complex comprising the steps of: a. pre drying of the pressed, unfired (green) tile so as to reduce the moisture content to less than 0.5%; b. treating the surface of the ceramic with an aqueous solution of metal complexes specially prepared by the method such as herein described, so as the colour penetratcs into the tile to a predetermined depth; c. firing the tiles to enable reaction between the said ions and tile matrix to form the required colours; and d. the desired shade and depth of colour in reflectance are adjustable varied by mixing different metal ions complexes and controlling the multivalent states of metal ions.
Full Text

This invention relates to a method for die manufacture of aqueous solutions of metal complexes and a method for the manufacturing high tanperature colouring vitreous glass-ceramic tiles.
FIELD OF TECHNOLOGY
This invention relates to the field of manufacture of aqueous solutioiK of metel complexes. Further, this invention relates to the field of coloiuing of vitreous glass-ceramic tiles usii^ these aqueous metal complexes. More particularly this invention encompasses a method of manufacturing of high tempwature coloured vitreous glass-ceramic tiles using aqueous solutions of metal complexes. The oivisaged application is on the permanent colouring of vitreous glass-ceramic tiles and their manufacture.
DESCRIPTION OF PRIOR ART
The coloured ceramic tiles and glass have been of use since ancient times. Thus far, primitive or average methods are only being used for the colouring of ceramics. Previously the method of colouring was the ^plication of glazes containii^ coloured pigments over an initially fired porous ceramic body and then fired a second time so that the applied layer yisX. melts and coats evenly on the surface of the body; thus making it coloured as desired and also making the surface impervious to water.
The alternative method was to add powdered colour pigments, in particular inorganic oxides and mineral colouring matters to clays, feldspars and other alimiinosiUcates to form vitrified tiles on firing. The ceramic manufactured article is thus coloured through its whole thickness with large consumption of the colouring matter, which is the most expensive component.
United States Patent No. 4,927,671 describes a method for producing colored decorations on ceramic products by foaming an aqueous suspension of a pigment containing at least one surface active agent, contacting a ceramic body with the foam to deposit ttie pigment on the body, and heating the ceramic body to a temperature of about 600.degree. to ISOO.degree. C.

United States patent No. 5,273,575 describes an ink that can be sprayed on an object in jets comprises: (a) zero (plus) to forty percent by mass of one or more metallic salts soluble in a solvent; (b) zero to forty percent by mass of one or more solvents; (c) zero to five percent of one or more organic dyes; (d) zero to ten percoit of a polymer; (d) one or more solvents which are more volatile than the solvent or solvents of (b).
LIMITATIONS
In the methods described above, there is a large consumption of the colouring material, which is the most expensive component, thereby also increasing by large magnitude, the manufacturing cost of the coloured vitrified ceramic tiles. Also, as there is no retention of the metal ions as silicates, the mechanical, thermal and other physical properties are affected by these processes. Further the manufacture of a vitrified poUshed tile in many different colours and designs as required is not adequately possible by any of the above methods.
OBJECTIVES OF THE INVENTION
It is the primary objective of the invention to invent a novel method, which provides a colouring formulation for vitrified tiles in the form of an aqueous solution suitable for obuining excellent shades.
It is another objective of the invention to invent a method of manufacturing high tonperature coloured vitreous glass-ceramic tiles using the said aqueous solutions of metal complexes, which is unique.
It is another objective of the invention to invent a novel method of colouring of vitreous glass-ceramic tiles by which the mechanical, thermal and other physical properties of the glass-ceramic tiles are not affected.
It is yet another objective of the invention to invent a method of manufacturing coloured vitreous glass-ceramic tiles whereby the metal ions of the colouring solution react with the tile matrix forming deep penetrating stable colours unlike existing methods.

PROPOSED SOLUTION
We propose a method for the manufacture of aqueous solutions of metal complexes, which can be used as high temperature colours on vitreous glass-ceramic tiles, which is unique and solves all the limitations mentioned above and addresses all the objectives mentioned above.
We further propose a method of manufacturing of high temperature coloured vitreous glass-ceramic tiles using aqueous solutions of metal complexes, for the low cost, deep penetrating, stable colouring of ceramic tiles.
BRIEF DESCRIPTION OF THE INVENTION
Sulphates, chlorides, or nitrates of the particular metal ions can be used as starting materials for manufacturing aqueous metal complexes, and may be particularly cheaper, but they suffer from the disadvantage of releasing highly corrosive vapours during the firing cycle. This makes the use of mono or polycarboxylic organic acids very critical in the manufacture of aqueous metal complexes. The inorganic salts of the colouring solution undergo complete thermal decomposition by a temperature of 400'C yielding carbon dioxide and water v^our. It is important that the compounds leave no carbon residue. Therefore the selection of the compounds becomes very restricted.
In the present method, the top surface of the un-fired (green) ceramic tile is caused to absorb, before firing, the aqueous solution of metal complexes, which become stable colours at high temperatures during the firing cycle. The colouring solution penetrates into the tile by way of bulk abso^'tion as a result of the c^illaiy actions provided by the fine clay particles and other raw materials.
In realizing the final fired colour of the tile, its bulk composition is very critical as much as the metal ions present in the colouring solution. The vitrified tile is essentially a composite material called glass-ceramics consisting of an amorphous glassy phase and crystalline particles of ceramics with sub-micron sizes produced in situ by nucleation and growth. The latter is brought e^out by specific control of time-temperature-transformation (TTT) parameters. The propaties of glass-ceramics are controlled by the physical properties of

the crystalline phases developed in the glass upon heat treatment. An important pre¬requisite for the formation of glass-ceramics is efficient nucleation of the crystalline phases. In most glass-ceramic systems, internal nucleatton is heterogeneous. The nucleatii^ agents, most commonly, re&actories such as zircon and rutile are added in the bulk composition. The crystalline phases observed are in many cases metastable, which may never develop under conditions of equilibrium crystallization. The glassy phase in the vitrified tile is alkali aluminosUicate. From this matrix, mullite and p-quartz crystallize out as the major ceramic phases.
Various methods for application of the colouring solution on to the ceramics are available such as immersion, spraying and silk screen technique. The silk screen printing technique is found to be the most suitable one. It is probably the only technique allowing a wide variety of patterns, designs, gr^hic decorations and drawings. Screen printing requires only lower quantities of colouring matter. A problem to be solved when using colours in an aqueous solution is the obtainable depth of colour penetration into the ceramic material. It was experimentally found that the depth of penetration depends on several parameters such as the viscosity and surface tension of the colouring solution, the application temperature, and the quantity of water sprayed after the colouring solution is ^plied and most importantly the nature of the raw materials of the tile.
The clays, aluminosilicates and other oxide raw materials absorb the colouring compounds after screen-printing as mentioned earlier. By controlling the wetness of the screen-printed layer, the extent of penetration can be altered. On firing, the compounds undergo tiiermal decomposition by 400 to 600°C, and the metal ions directly form their respective silicates without the formation of separate metal oxide phase. These silicates, at higher temperatures form a part of the alununosilicate glassy matrix forming stable permanent colours. The depth of diffusion of the metal ions into the glassy matrix is limited by the thermal processing cycle, i.e. by the TTT parameters. As a result of the restricted diffusion lengths, the coloured region produced by the high temperature process is restricted on to the top surface of the tile, as also the printed pattern is retained mtact even after firing. The retention of the metal ions as silicates is more towards the glass matrix and is least distributed within the crystalline particles nucleating therefrom. By this process, the

mechanical, thermal and other physical properties are in no way affected by the colouring metal ions.
With the present method, a single tile can be coloured in as many different shades and designs as required. This is a clear advantage especially for a continuously running plant.
Figure 1 of the accompanying drawings illustrates X-ray diffraction patterns of glass-ceramic composites showing the time-temperature-transformation characteristics (A) 1200 °C, 15 minutes (B) 1200 'C, 30 minutes (C) 1250 °C, 60 minutes.
The figure specifically shows the TTT characteristics of mullite,p-quartz, zircon and a-alumina as marked.
DETAIL DESCRIPTION OF THE INVENTION
This process of colouring vitreous glass-ceramic tiles is hereunder described in six parts, viz.
1) Chemical Synthesis of the colouring solutions,
2) Processing,
3) Printmg,
4) Firing,
5) Polishing and
6) Characterization along with examples, tables and drawing as follows. Chemical synthesis of t(ie colourtng sotutions
10.00 kg
1.82 kg
2.00 litres
0.84 litres
distilled or deionised water
8% by weight
Preparation of the nickel complex:
Total weight
Nickel hydroxy carbonate (with 44% Ni)
Glacial acetic acid
Cone. Ammonia (liquor) solution
Medium
Nickel content

Nickel carbonate is used for the preparation of the nickel complex. The above-mentioned quantity of the hydroxy carbonate is added to a mixture of acetic acid (2 litres) and distilled water (3 litres) heated to a temperature of 70 - SO^C. The carbonate decomposes liberating carbon dioxide and water. The nickel forms the 'acetato' complex. This solution is further neutralized using ammonia solution up to a pH value of 6 - 7. It is then filtered to remove any residue if present. The solution is further diluted using distiUed/deionised water to attain a total weight of 10 kg to maintain 8% of nickel in the solution.

Preparation of the copper complex:
Totai weight 10.00kg
Copper carbonate (with 54% Cu) 1.13kg
Ethylene Diamine Tetra Acetic Acid 'disodium salt 3.69 kg
Cone. Ammonia (liquor) solution 0.40 litres
Medium distilled or deionised water
Copper content 8% by weight
Cupric carbonate, which is also a hydroxy carbonate, is used to prepare the copper complex. The copper is chelated using etiiylenediaminetetiaaceticacid (EDTA). The disodium salt of the EDTA is used. The EDTA is first heated with dJstilled/deionised water (3 litres) to about SO^C. The carbonate is added slowly with stiiring. It dissociates liberating carbon dioxide and water. The copper complexes with the EDTA in a 1:1 molar ratio. Filtration is done if necessary. The copper content of the solution is maintained at 8 % by the addition of distilied/deionised water to bring the final weight to 10 kg.

Preparation of the cobalt complex:
Total weight
Cobalt (II) hydroxy carbonate (with 46% Co)
Glacial acetic acid
Cone. Ammonia (liquor) solution
Medium
Cobalt content

10.00kg
1.74kg
1.90Utres
0.80 litres
distilled or deionised water
8% by weight

The hydroxy carbonate of cobalt is used for the preparation of the cobalt complex. The required quantity of the carbonate is added slowly with stirring to a mixture of acetic acid (1.9 litres) and distilled/deionised water (3 litres), heated to about 80"C. The carbonate dissociates liberating carbon dioxide and water. The cobalt forms the acetate. It is neutralized using ammonia solution to a pH value of 6 - 7. The solution is filtered to remove any residue if present. The solution is fiirthw diluted using distilled/deionised water to attain a total weight of 10 kg to maintain 8% of CobaJt in the solution.

8% by weight
Ammonium meta vanadate is used for the preparation of the vanadium complex. Since the oxidation state of vanadium is +5 in the meta vanadate, it is reduced to +4 by the use of a reducing agent mainly oxalic acid. The oxalic acid also fonns soluble oxalate complex of the vanadium, thus retaining the vanadium (+4) ions in solution.
The above mentioned amount of the vanadate is mixed with oxalic acid and distilled/ deionised water (3 litres) and heated slowly. The vanadate gets reduced and forms stable oxalate complex. The pH of this complex is brought to 5 to 5.5 by adding the cone. Ammonia solution. The concentration of Vanadium is maintained at 8% by adding distilled/deionised water to bring the final weight to 10 kg.
Preparation of tlie iron complex:
PreparatiDD of the vanadium (TV) complex:
Total weight
Ammonium meta vanadate
Oxalic acid
Cone. Ammonia (liquor) solution
Medium
Vanadium content
Total weight
Ferric chloride hydrate
Imino di acetic acid
Cone. Ammonia (liquor) solution
Medium
Iron content

10.00kg
2,00kg
2.60kg
0.55 litres
distilled or deionised water
10.00 kg
3.87 kg
3.05 kg
1.00 litres
distilled or deionised water
8% by weight

The iron complex is prqiared from its hydroxide. The iron is chelated using Imino DiaceticAcid (IDA).
The hydroxide is prepared from ferric chloride by precipitation using ammonia solution. The hydroxide obtained is washed free of chloride and complexed with IDA by heating the mixture to about 60 - lOfC with constant stirring. Neufralization is done usmg ammonia solution. The concentration of iron is maintained at 8 % by adding required quantity of distilled/deionised water to bring the fmal weight to 10 kg.
Preparation of the chromium complex:
Total weight : 10.00 kg
Chromic Oxide (Chromium (VI) Oxide) : 1.54 kg
Acetic acid : 1.25 litres
Hydrogen peroxide (100 volumes) : 6.50 litres
Cone. Ammonia (liquor) solution : 0.30 litres
Medium : distilled or deionised water
Chromium content : 8% by weight
The chromium (III) complex is prepared by using chromium (VI) oxide. The latter is added slowly with stirring to a mixture of acetic acid and hydrogen peroxide. The chromic oxide dissolves in this mixture accompanied by its reduction and the chromium (III) forms a stable complex. The pH of the solution is maintained at 5 - 6 by adding cone, ammonia solution. The concentration of chromium is maintained at 8 % by adding distilled/deionised water to bring the final weight to 10 kg.
Processtng
The Glass-Ceramic Tiles
The colour developed after vitrification of the tile depends on the bulk composition of the tile as much as the metal ions. Hence it is important to specify the composition of the tile to be coloured.

The raw materials used for making the tiles are mainly ball clay, china clay, sodium and potassium feldspars, zirconium silicate and calcined alumina. The typical bulk composition is given in Table 1.

The vitrified tile is essentially a body consisting of crystalline ceramic phases dispersed in an amorphous glassy matrix. . The amorphous phase is alkaU aluminosiUcate. From this amorphous matrix, mullite and quartz particles crystallize out as the ceramic phases, generating the glass-ceramic composites. The coloiuing ions remain within the glassy phase and do not alter the course of the crystallization. They also do not affect the thermal as well as the mechanical properties of the glass ceramics.
Figure 1 shows the X-ray diffraction patterns of the glass-ceramic composite. Figure 1 (A) is the diffraction pattern of the ceramic heated tolZOO^C, 15 minutes. Mullite, p-quartz and zircon are the major phases crystallizing out of the glassy matrix. The broadness of these peaks indicates that these crystallites are of nanometer size. Figure 1(B) shows the same composition heated to 1200°C, 30 minutes. An increase in dwell time makes the crystallites to grow into 100-300 nanometer size. This is indicated by the increase in intensity and sharpness of the respective peaks. Figure 1(C) shows the diffraction pattern of the same composition heated to HSO^C, 60 minutes. The crystalline particles have

grown to sub-micron sizes. The raetastable p-quartz is now slowly converted to p-quartz. The composite described in Figure 1(A) is found to be more siqierior in its physical properties. This is because of the nanometer size of the particles within the glassy matrix.
Prinrini^
The silk screen-printing technique is found to be the most suitable method for application of the colouring solution. It is probably the only technique allowing graphic decorations and drawings, and requiring lower quantities of colouring matter.
The aqueous solution of the colouring matter is fu^t mixed with a thickening agent, mostly starch derivatives, cellulose and modified cellulose derivatives, or other polymeric substances, soluble or dispersible in an aqueous solution in order to increase the viscosity of the solution. An antifoaming agent is also added to the solution. The mixture thus fonns a paste ready for printing.
The pressed tile is first dried completely to moisture content of less than 0.5%. It is then sprayed with water on the surface wherein the amount of water grayed is about 150 -200g/m^. The required design is then printed on the tile with the paste prepared. The amount of colouring matter required will vary from 25 - 300 g/m^ depending on the design. The printed surface is again sprayed with water of about 250 - 300 g/m^. The tile is then kept for 10 - 40 minutes at a temperature of 40 - 60"C for homogeneous absorption of the colour. The colour penetrates to a depth of at least 2-3mm.
£MSS
The tile is dried completely and fired in a roller hearth kiln at a standard fuing cycle reaching a maximum temperature of about HOO^C. The organic matters present are thermally disintegrated totally by a temperature of about 400*'C, mainly forming carbon dioxide and water vapour. The metal ions react with the matrix forming their respective silicates, and thereby forming highly stable colours.

The vitrified decorated tile will have a slightly uneven and rough surface. It is therefore 'smoothened' at the surface by removing a layer of about 0.5 to 1.5 mm thick by using diamond and silicon carbide based abrasives in steps starting from the coarsest grade to the finest. The tile will have a smooth, plain and glossy surface after the final polishmg.
Charftcterlzfitioii
The colour of the ceramic tile has been measured according to the CIE formula, wherein the values are measured as L*, a*, b*.
The L*- axis indicates the lightedness (brilliance) of a colour. The a*- axis gives the red -greai share and the b*- axis the yellow - blue share. The L*- values are always positive, with 0 for ideal black and 100 for ideal white colours. Red shades have positive a*-values, whereas green shades have negative ones. Yellow shades have positive b*- values, blue shades have negative ones.
The instrument used for the measurements is 'Himter Lab' manufactured by Hunter Associates Laboratory, USA. The instrument has been calibrated with white and black reference samples provided with the instrument showing the following values: White: L* = 94.11 a*=-1.3] b*=l.ll Black; L* = 0.33 a* = -0.29 b* = -0.19
The values of the shades obtained using the colouring solutions on the tiles of the composition mentioned in Table I are given in Table 2.






REFERENCES
1. T. Emiliani Once pressed single flred glazed floor tiles, Ceramurgia International, Volume 2, Issuel (1989)
2. Ceramics glaze technology: J.R. Taylor and A.C. Bull (Pergamon Press, Oxford, 1986)
3. P. Burzacchinj, Porcelain tile, its history and devdopment, Ceram. World Rev. 10 (37) (2000) 96103
4. T. Manfredini, Porcelainlsed stoneware tiles, Am. Ceram. Soc. Bull. 74 (5) (1995) 76-79
5. Corradi Preparation and properties of fast-fired porcelain tiles containing natural cliromite. ^m. Ceram. Soc. Bull.. 72 (1993)., 63 69
6. United States Patent, Nawothnig 4,927,671 May 22,1990
7. United States Patent, de Saint Romain 5,273,575 December 28,1993


WE CLAIM:
1. A method for the manufacturing of aqueous solutions of metal complexes comprising the step of adding the selected metal compound to a solution of one or more organic acids; heating the mixture formed to near boiling temperatures wherein redox reactions take place to form stable complexes with the organic complexing agents, removing the complex so formed by conv^tional methods.
2. A method as claimed in claim 1, wherein the said metal cations are iron, cobalt, nickel, vanadium, chromium, manganese, copper, ruthenium, palladium, zirconium, gold and mixtures thereof, and are derived from their respective carbonates, oxalates or hydroxides.
3. A method as claimed in claim 1, wherein the complexing agents of the said metal complexes are mono or polycarboxylic organic acids such as acetic, formic, propionic, butyric, lactic, glycolic, tartaric, citric, oxalic, maleic, ethylenediamine tetraacetic, iminodiacetic, iumaric, and salicylic acid.
4. A method as claimed in claim 1, wherein the said complexes formed are neutralized with hydroxides of sodium, potassium or ammonium to maintain a pH value of 4.0 to 8.0.
5. A method as claimed in claim 1, wherein the said aqueous solutions contain not less than 3 to 8% by weight of the elemental metals.
6. A method as claimed in claim 1, wherein the aqueous solutions is thickened using thickening agents such as starch derivatives, cellulose and modified cellulose derivatives, or other polymeric substances, soluble or dispersible in an aqueous solution.
7. A method of manufacturing high temperature coloured vitreous glass-ceramic tiles using aqueous solutions of metal complex comprising the stqis of:

a. pre drying of the pressed, unfired (green) tile so as to reduce the moisture contenX
to less than 0.5%;
b. treating the surface of the ceramic with an aqueous solution of metal complexes
specially prepared by the method such as herein described, so as the colour
penetrates into the tUe to a predetermined depth;
c. firing the tiles to enable reaction between the said ions and tile matrix to form the
required colours; and
d. the desired shade and depth of colour in reflectance are adjustably varied by
mixing different metal ions complexes and controlling the multivalent states of
metal ions.
S. A method as claimed in claim 7, wherein the penetration depth is at least 1 mm.
9. A method as claimed in claim 7, wherein the said glass-ceramic composites are mainly vitrified silicate tiles with water absorption of less than 0.05% produced by single firing process wherein the crystallization of the ceramic phases are controlled by the time-temperature-transformation parameters and nucleating agents added into the bulk composition.
10. A method as claimed in claim 7, wherein the aqueous solutions of the colouring components are organic complexes of metal cations, mainly iron, cobalt, nickel, vanadium, chromium, managanese copper, ruthenium, palladium, zirconium, gold, and mixtures thweof.
11. A method as claimed in claim 10, wherein the said organic compounds are mainly mono or polycarboxylic organic acids such as acetic, formic, propionic, butyric, lactic, glycolic, tartaric, citric, oxalic, maleic, etheyienediamine tetraacetic, iminodiacetic, fumaric, and salicyclic acid, neutralized with sodium, potassium or ammonium, preferably ammonium.

12. A method as claimed in claim 10, wherein the said aqueous solutions contain not less than 6-8% by the weight of the elemental metal.
13. A method as claimed in claim 10, wherein the said ceramic tile is decorated prior to firing by the ^plication of the said aqueous solution of the carrying component by the silk screen - printing technique.
14. A method as claimed in claim 13, wherein the aqueous solution is thickened using thickening agents such as starch derivatives, cellulose and modified cellulose derivatives, or other polymeric substances, soluble or dispersiWe in an aqueous solution.
15. A method as claimed in claim 13, wherein the said green tile is treated on the surface with water after printing in order to facilitate penetration of the colour.
16. A method as claimed in claim 15, wherein the colour reaches a penetration depth of 2 to 3 mm in the green stage as a result of the reactions between the colouring solutions and the raw materials, mamly clays and alkali substances.
17. A method as claimed in claim 13, wherein the said decorated tile is dried completely and fired at a standard firing cycle to yield completely vitrified tiles having the colour on desired face whereas the remaining part of the tile remams uncoloiu'ed for the efficient utilization of colouring agents.
18. A method as claimed in claim 10, wherein the said organic complexes disintegrate totally by 400-500° C giving away mainly carbon dioxide and water and leaving behind the no carbon residue.
19. A method as claimed in claim 18, wherein the metal ions of the said complexes mainly form their respective silicates, eventually producing very stable colours and retain the desired patterns generated by screen - printing and that the coloured metal silicates form a part of the vitreous phase within the tile.

20. A method as claimed in claim 17, wherein the said vitrified tiles are 'smoothened' by
removing surface layer maximum up to depth of 0.5 to 1.5 mm, followed by final
polishing to yield single or multi-coloured patterns in reflected light.
21. A method as claimed in claim 10, wherein the said colouring solutions are compatible
for utilization in high temperature colouring process, and not affect the thermal,
mechanical and other physical properties of the tiles neither after firing nor with time
or preservation.


Documents:

0626-mas-2002 abstract duplicate.pdf

0626-mas-2002 abstract.pdf

0626-mas-2002 claims duplicate.pdf

0626-mas-2002 claims.pdf

0626-mas-2002 correspondence-others.pdf

0626-mas-2002 correspondence-po.pdf

0626-mas-2002 description (complete) duplicate.pdf

0626-mas-2002 description (complete).pdf

0626-mas-2002 drawings duplicate.pdf

0626-mas-2002 drawings.pdf

0626-mas-2002 form-1.pdf

0626-mas-2002 form-13.pdf

0626-mas-2002 form-26.pdf

0626-mas-2002 form-5.pdf

0626-mas-2002 petition.pdf


Patent Number 197957
Indian Patent Application Number 626/MAS/2002
PG Journal Number 27/2006
Publication Date 07-Jul-2006
Grant Date 07-Apr-2006
Date of Filing 26-Aug-2002
Name of Patentee INDIAN INSTITUTE OF SCIENCE
Applicant Address BANGALORE 560 012, KARNATAKA STATE
Inventors:
# Inventor's Name Inventor's Address
1 DR.T.R.N. KUTTY, MATERIAL RESEARCH CENTRE INDIAN INSTITUTE OF SCIENCE, BANGALORE - 560 012, KARNATAKA STATE.
2 MATHEW, MR. V.T. EXECUTIVE (CERAMICS), M/S. H & R JOHNSON (INDIA) LIMITED, MUMBAI
3 MAHAPATRA, MR.S.S. TRAINEE EXECUTIVE (CERAMICS), M/S. H & R JOHNSON (INDIA) LIMITED, MUMBAI
4 CHITWADGI, MR.S., EXECUTIVE (CERAMICS), M/S. H & R JOHNSON (INDIA) LIMITED, MUMBAI
5 KULKARNI, MR. M. G. EXECUTIVE (CERAMICS), M/S. H & R JOHNSON (INDIA) LIMITED, MUMBAI
PCT International Classification Number C04B33/13
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA