DESC:
FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
As amended by the Patents (Amendment) Act, 2005
&
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2006

COMPLETE SPECIFICATION
(See section 10 and rule 13)

TITLE OF THE INVENTION
A ceramic glaze composition for porcelain insulators.

APPLICANTS
Grasim Industries Ltd, Unit-Aditya Birla Insulators, Taluk: Halol, PO: Maghasar - Halol, Dist: Panchamahal, Gujarat- 389350, India.

PREAMBLE TO THE DESCRIPTION

FIELD OF THE INVENTION
[001] This invention relates to a ceramic glaze composition for porcelain insulators. More particularly, the invention relates to a glaze composition that eliminates requirement for dry finishing of an insulator before glazing.

BACKGROUND OF THE INVENTION
[002] During the manufacturing of porcelain insulators, ‘Dry Finishing’ is one of the important process which is practiced throughout the porcelain insulator industries since inception as an additional surface finishing step of dried insulators.
[003] Dry finishing is carried out before application of the glaze in order to remove residual lines on the insulator surface post shaping of the insulators on lathe machines. The purpose of dry finishing is to facilitate uniform coating of the glaze layer on the entire insulator surface. Generally, dried insulators are dry finished by placing the insulators on the rotating table horizontally and while in rotation net wire mesh of 80 Mesh# so is used as to remove the surface blemishes like- rough lines and scratches and imperfections. The loose and dried particles fly all over the room and it is detrimental to the persons working as well as affects the environment. Moreover, if these imperfections are not removed, after glaze application and firing, the finished ware will not have the required finish and surface smoothness.
[004] However, there are various issues related to dry finishing process such as generation of a massive amount of fine dust making the area potentially environmental non-friendly & an ooccupational hazard. Also, dry finishing of an insulator involves huge manpower affecting the overall productivity. Lastly, the process of dry finishing involves the operator in touching the insulator many times which leads to unsafe situations & handling rejections (Green & Fired).
[005] CN102515855B recites a composition for ceramic glaze product for insulator, comprises potassium feldspar, quartz power, Syria soil, limestone, soapstone, spodumene steatite, barium carbonate, high-strength material, common blank, and carboxymethyl cellulose.
[006] US4839313 recites a glaze composition for a ceramic substrate consisting essentially of 55 to 75 mol% SiO2, 1 to 15 mol% Al2 O3, 3 to 20 mol% CaO, 1 to 13 mol% BaO, 1 to 5 mol% Y2 O3, 0 to 25 mol% SrO, 0 to 7 mol% B2 O3, 0 to 2 mol% ZnO, and 0 to 2 mol% MgO, and containing at least one of SrO, B2 O3, ZnO and MgO.
[007] US5922444 recites a glaze composition consisting of the following components, on the basis of oxide weight: 20% to 50% by weight of boron oxide; 5% to 35% by weight of aluminum oxide; greater than 0% up to less than 40% by weight of silicon dioxide; greater than 0% up to less than 8% by weight of zinc oxide; and 15% to 55% by weight of at least one alkaline-earth oxide selected from the group consisting of calcium oxide, strontium oxide, magnesium oxide and barium oxide.
[008] US20190276373 recites a glaze for a ceramic article, comprising: 5%-15% graphane or C-doped boron nitride.
[009] EP 1124 237 A2 discloses a glazed ceramic article. The glaze layer comprises SiO2 and Al2O3 and does not show a feature of acting hydrophobic or self-cleaning.
[010] U.S. Pat. No. 5,284,712 describes a cement-containing ceramic article comprising a glaze layer of 40% Feldspar, 10% Calcium Carbonate, 5% Zinc Oxide, 25% Talc, 10% Silica Sand and 10% Silica-containing Kaoline. This glaze does not have efflorescence, however, it is not designed to act hydrophobic or self-cleaning.
[011] The glaze compositions that are currently available in the market cannot be used directly on the dry insulator surface as it does not provide the smoothness and stability.

SUMMARY OF THE INVENTION
[012] The present invention intends to overcome the above problems of the prior art, and the object of the present invention is to provide a glaze composition for ceramic insulators.
[013] The objective of the present invention is to eliminate the dry finishing process by formulating a new glaze composition which is unique in nature to take care of the surface finish of the dried insulators without requiring surface finishing.
[014] A further object of the invention is to provide a glaze composition which can easily form an extensively smooth glaze layer
[015] To attain these or other objects, a first embodiment of the present invention provides a glaze composition comprising waste insulator powder added in the range of 5% to 50% and china clay in the range of 1 to 10%.

BRIEF DESCRIPTION OF THE INVENTION
[016] In describing and claiming the invention, the following terminology will be used in accordance with the definitions set forth below. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods and materials are described herein. As used herein, each of the following terms has the meaning associated with it in this section. Specific and preferred values listed below for individual process parameters, substituents, and ranges are for illustration only; they do not exclude other defined values or other values falling within the preferred defined ranges.
[017] As used herein, the singular forms "a," "an," and "the" include plural reference unless the context clearly dictates otherwise.
[018] The terms “preferred” and “preferably” refer to embodiments of the invention that may afford certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the invention
[019] As used herein, the terms “comprising” “including,” “having,” “containing,” “involving,” and the like are to be understood to be open-ended, i.e. to mean including but not limited to.
[020] The term “insulator” used herein refers to properties of insulators meeting IEC C130 Class.
[021] The term “glaze” used herein refers to a mixture of oxide used coat on insulator for making insulator impervious, mechanically strong and resistance to all chemical, physical and corrosive environment.
[022] The term “waste insulator powder” refers to insulators headers and footers cut after firing ground in the ball mill to require size for use in the glaze is called Waste insulator powder.
[023] The term “firing” refers to the act or process of heating of Insulators as per ABI Master Graph still complete verification of product in both oxidation and reduction atmosphere is called firing.
[024] The raw materials of the glaze composition are added in such a way so as to establish good physical flow of the materials during firing process and cover the entire surface and fill in between the turning / shaping green are lines or defects.
[025] A glaze composition comprising waste insulator powder added in the range of 5% to 50%, wollastonite in the range of 10-20%, quartz in the range of 10-20%, feldspar in the range of 15-25%, talc in the range of 0.5-10%, dolomite in the range of 0.5-2%, bentonite in the range of 0.5-1%, chromium oxide in the range of 0.1-1.5%, manganese carbonate in the range of 4-10%, iron oxide in the range of 0.5-3%, barium carbonate in the range of 1-5% and china clay in the range of 1 to 10%.
[026] In an aspect, the waste insulator powder comprises of the following ingredients.
a) 35-40 % of Aluminum Oxide
b) 55-65 % of Silicon dioxide
c) 2-5% of Potassium Oxide
d) 1-2% of Sodium oxide
e) 1-2% of Magnesium oxide
f) 1-2% of Calcium oxide
g) 2-3% of Titanium oxide
h) 2-3% of Ferrous oxide

[027] In an embodiment, the ratio of waste insulator powder to china clay in the glaze composition is in the range of 6:1.
[028] In an embodiment, the average particle size of waste insulator powder is 75 Micron. This particle size of waste insulator powder is maintained at 75 microns so as to have enhanced glaze flow and glaze rollout after firing.
[029] In another embodiment, the glaze composition is prepared by milling waste insulator powder along with china clay for a duration in the range of 30-35 hours.
[030] The new glaze composition develops a very good surface coverage on the green wares, and because it contains clay content which results in an increase in the glaze thickness by 0.04 to 0.05 microns (10% to 12%) thereby resulting in after firing glaze thickness which has significant effect on covering the surface roughness and ensuring smooth glaze appearance.
[031] It was observed that the clay content in the glaze composition makes very sensitive to seasonal climate changes. When the clay content was increased from 16.01% to 20%, the properties like viscosity and pH significantly vary leading to improper application on the dipping process and there was high differential shrinkage leading to glaze crack and after firing this will appear as glaze rolling. Considering the above, the clay content is maintained in the range of 1 to 10% in the glaze composition.
[032] The new glaze composition displayed no settling tendency across all ambient temperature and pressure. The glaze become non expire and glaze wastage drastically reduce. The Glaze pH Remain stable and helping to keep the glaze mixture at homogeneous conditions.
[033] The properties of the glaze composition include density in the range of 1.65-1.66 gram/cc, viscosity in the range of 200 to 220 cps.
[034] The density of Glaze playing very important role in the dipping process of Insulator process. The advantages are as follows
[035] The higher density of glaze composition in the present application eliminates the need for multiple glaze dipping of the insulator. Where the density of glaze composition is less, the insulator is dipped at least 4-5 times in the glaze as a result glazing productivity also increased significantly.
[036] It is very difficult to make higher density glaze for dipping process and it is decided by glaze recipe. Glaze Ball Mill capacity also increase due to high density charging capacity increase at fix volume of Ball Mill.
[037] Viscosity is the function of density and temperature of the glaze. The optimum viscosity helps to control glaze after dipping. The viscosity important for complicate shape insulator dipping process. The glaze should not accumulate in the bore or between the sheds.
[038] Moreover, the glaze composition available in the prior art the old glaze requires external cooling but the glaze of the present invention works perfectly fine without any external cooling while glazing of the insulator.
[039] The waste insulator powder renders the glaze composition to work without external cooling. The waste insulator is pure inert material calcined at 1300 degree with reduction atmosphere and this is playing very critical role in making the glaze seasonal stable and no expire.

WORKING EXAMPLES:
[040] 350kg of waste insulator powder was obtained by milling a waste insulator having the following ingredients.
Material UOM Al2O3 SiO2 K2O Na2O MgO CaO TiO2 FeO
Waste Insulator Powder % 39.83 61.26 4.56 1.51 1.11 1.25 2.86 2.8

[041] 58kgs of china clay was added to the milled waste insulator powder and mixed thoroughly to obtain a dry glaze composition. The glaze composition as applied on to a ceramic insulator by dipping the ceramic insulator in the glaze composition. The glaze coated ceramic insulator was subjected to firing.
[042] The properties of glaze composition of present invention are compared with the properties of already available glaze composition having following ingredients.

Table 1
Glaze Comparisons(Matrix)
# Ingredients Old Glaze New Glaze
1 Quartz 12-18% 10-20%
2 Feldspar 15-23% 15-25%
3 China Clay 4-7% 1 to 10%
4 Calcined Alumina 5-7% -
5 Talc 0.5-7% 0.5-10%
6 Iron Oxide 0.50- 3.0% 0.5-3%
7 Zinc oxide 1.0 -3.0% -
8 Manganese carbonate 4-10% 4-10%
9 Chromium oxide 0.1-1.5% 0.1-1.5%
10 Zircosil 4.0-7.0% -
11 Barium carbonate 1-5% 1-5%
12 Dolomite 0.5-2% 0.5-2%
13 Wollastonite No 10-20%
14 Bentonite No 0.5-1%
14 Waste insulator No 5% to 50%

Table 2
Comparisons of Old and New Glaze (Properties )
A Parameters UOM Old Glaze New Glaze
1 Glaze Loss on ignition % 8.5-9.0 4.0-5.0
2 Fired Glaze flow ( At 45 degree) Mm 60-64 64-68
3 Thermal Expansion % 0.29-0.31 0.28-0.30
4 Glazed MOR Kg/sq,cm 1650-1680 1670-1700
5 Glaze thickness before firing Micron 440-480 440-480
6 Glaze thickness after firing Micron 300-320 340-360
7 Shrinkage % 32% 24%

[043] As shown in table 2, the glaze composition of present application experiences less shrinkage in comparison with the known glaze composition. In addition, the glaze thickness in insulator coated with the glaze composition of present invention is in comparison with the known glaze.
[044] The glaze composition of present invention eliminates the exposure to fine dust (occupational hazard) during dry finishing process. This in turn increases the productivity due to manpower reduction with overall yield improvement by 5%. Elimination of dry finishing also leads to higher throughput & reduced lead time thus a step towards lean manufacturing. Since the glaze composition uses waste insulator powder, significant cost savings have been achieved.
[045] The foregoing description of specific embodiments of the present invention has been presented for purposes of description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obvious modifications and variations are possible in light of the above teaching.
,CLAIMS:
We claim

1) A glaze composition comprising waste insulator powder added in the range of 5% to 50%, wollastonite in the range of 10-20%, quartz in the range of 10-20%, Feldspar in the range of 15-25%, talc in the range of 0.5-10%, dolomite in the range of 0.5-2%, bentonite in the range of 0.5-1%, chromium oxide in the range of 0.1-1.5%, manganese carbonate in the range of 4-10%, iron oxide in the range of 0.5-3%, barium carbonate in the range of 1-5% and china clay in the range of 1 to 10%.

2) The composition as claimed in claim 1, wherein said waste insulator powder comprises of
a) 35-40 % of Aluminum Oxide
b) 55-65 % of Silicon dioxide
c) 2-5% of Potassium Oxide
d) 1-2% of Sodium oxide
e) 1-2% of Magnesium oxide
f) 1-2% of Calcium oxide
g) 2-3% of Titanium oxide
h) 2-3% of Ferrous oxide

3) The composition as claimed in claim 1, wherein the average particle size of glaze composition is in the range of 1 to 2.5 Micron.

4) The composition as claimed in claim 1, wherein the average particle size of waste insulator powder in the composition is in the range of 70 to 75 microns.
5) The composition as claimed in claim 1, wherein the average particle size of china clay in the composition is in the range of 0.5 to 1.5 micron.

6) The composition as claimed in claim 1, wherein the density of the glaze composition is in the range of 1.65-1.66 gram/cc.

7) The composition as claimed in claim 1, wherein the viscosity of the glaze composition is in the range of 200 to 220 cps.

8) The composition as claimed in claim 1, having a thermal expansion co-efficient in the in the range of 0.28 to 0.30.

9) A ceramic article comprising a surface glaze made of a glaze composition according to claim 1.

Dated this 23 March 2021
Digitally Signed
M. Kisoth
IN/PA-2259
Agent for the Applicant