FORM 2
THE PATENTS ACT, 1970
(39 OF 1970)
&
THE PATENT RULES, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
“COATED COOLING PAD AND THE PROCESS FOR MAKING THE SAME”
We, Bajaj Electricals Ltd., an Indian National, of, 45/47, Veer Nariman Road, Fort, Mumbai - 400001, Maharashtra, India.
The following specification particularly describes the invention and the manner in which it is to be performed:

FIELD OF INVENTION
The present invention generally relates to the field of passive cooling solutions. In particular, the present invention provides an evaporative cooling pad having a coating to enhance cooling effect.
BACKGROUND OF THE INVENTION
Cooling pads are essential in a variety of appliances, including industrial and domestic air cooler, etc. Cooling pads available in the market are expensive and relatively short-lived unless heavily treated with chemicals. A preferred type of cooling pads is especially evaporative cooling pad made of cellulosic materials having pores on their surface, which offers a high level of water absorption, absorption, and retention, all of which are essential for an evaporative cooling pad. Additionally, cellulosic materials are available in various forms and sizes to suit the need of a multitude of customers, making them an ideal choice. The most desirable property of cellulose-based cooling pads is its affinity towards water molecules. While this property is crucial for cellulose materials to be efficient, exposure to water eventually hampers the original from and therefore efficiency of the cellulosic material.
The challenge therefore lies in using cellulosic material for affinity towards water molecules without allowing the water to damage the material itself. Cellulose pads with coating have therefore become an obvious solution to the much-needed issue. Commercially available cellulose pads have limited water absorption capacity which is naturally proportional to the cooling effect it generates. The coatings used on commercially available cellulose pads tend to limit the heat exchange due to partial exposure of cellulose pores towards water molecules.
Therefore, there is a need for a cellulose pad with coating which does not hinder its cooling efficiency, while at the same time protecting its original form. Hence, there is a need to overcome at least one of the above-mentioned limitations.
SUMMARY OF THE INVENTION
It is to be understood that this disclosure is not limited to the particular embodiments, as there can be multiple possible embodiments which are not expressly illustrated in the present

disclosure. It is also to be understood that the terminology used in the description is for the purpose of describing the particular versions or embodiments only and is not intended to limit the scope of the present invention. This summary is not intended to identify essential features of the claimed subject matter nor is it intended for use in determining or limiting the scope of the claimed subject matter.
In an aspect of the present invention, there is provided an aqueous coating composition for evaporative cooling pad comprising: (a) a material selected from the group consisting of at least a cellulose derivative, at least a clay, and combination(s) thereof; and (b) at least a resin.
In an aspect of the present invention, the cellulose derivative is selected from the group consisting of carboxy methyl cellulose (CMC), hydroxyl ethyl cellulose (HEC), hydroxypropyl cellulose, carboxymethyl cellulose, and combinations thereof.
In an aspect of the present invention, the clay is selected from the group consisting of montmorillonite, bentonite, kaolin, hectorite, halloysite, and combinations thereof.
In an aspect of the present invention, the resin is a formaldehyde resin.
In yet another aspect of the present invention, the formaldehyde resin is selected from the group consisting of phenolic-formaldehyde resin (P-F resin), melamine-formaldehyde resin (M-F resin), and combinations thereof.
In yet another aspect of the present invention, the cellulose derivative weight concentration is in the range of 0.2-2wt%; clay weight concentration is in the range of 0.05-2wt%; and resin weight concentration is in the range of 50-80wt%.
In still another aspect of the present invention, there is provided an evaporative cooling pad coated with a composition comprising: (a) a material selected from the group consisting of at least a cellulose derivative, at least a clay, and combination(s) thereof; and (b) at least a resin.
In an aspect of the present invention, the evaporative cooling pad has a porous honeycomb structure.

In an aspect of the present invention, the evaporative cooling pad comprises a plurality of sheets.
In an aspect of the present invention, the sheet is cellulosic paper sheet.
In yet another aspect of the present invention, there is provide a method of manufacturing evaporative cooling pad coated with a composition comprising: (a) a material selected from the group consisting of at least a cellulose derivative, at least a clay, and combination(s) thereof; and (b) at least a resin, said method comprising: (i) coating at least a sheet surface with the composition to obtain a coating having thickness in the range of 4-8µm; (ii) drying the sheet at a temperature in the range of 100-130C for 2-15 seconds; (iii) corrugating the dried coated sheet; and (iv) curing the corrugated and dried sheet at a temperature in the range of 18-200C for 5-20 seconds.
In yet another aspect of the present invention, the method comprises adhesively binding a plurality of cured corrugated and dried sheets to obtain a stack of sheets.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 depicts the porous honeycomb evaporative cooling pad of the present invention, in accordance with an embodiment of the present invention.
Figure 2 depicts a representation of the cooling mechanism achieved by the coated evaporative pad of the present invention, in accordance with an embodiment of the present invention.
Figure 3 depicts the coated surface of the evaporative cooling pad of the present invention, the coating comprising clay particles and/or cellulose derivatives mixed with resin, in accordance with an embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Some embodiments of the present disclosure, illustrating all its features, will now be discussed in detail. It must also be noted that as used herein and in the appended claims, the singular forms "a", "an" and "the" include plural references unless the context clearly dictates

otherwise. Various modifications to the embodiment will be readily apparent to those skilled in the art and the generic principles herein may be applied to other embodiments. However, one of ordinary skill in the art will readily recognize that the present disclosure for an improved coated cooling pad is not intended to be limited to the embodiments illustrated but is to be accorded the widest scope consistent with the principles and features described herein.
The present invention provides an aqueous coating composition for evaporative cooling pad comprising: (a) a material selected from the group consisting of at least a cellulose derivative, at least a clay, and combination(s) thereof; and (b) at least a resin.
In an embodiment of the present invention, the cellulose derivative is selected from the group consisting of carboxy methyl cellulose (CMC), hydroxyl ethyl cellulose (HEC), hydroxypropyl cellulose, carboxymethyl cellulose, and combinations thereof. In a preferred embodiment, the cellulose derivative is HEC. In an embodiment of the present invention, the cellulose derivative weight concentration is in the range of 0.02-1wt%. In a preferred embodiment, the concentration is 0.02-0.08wt%. In a more preferred embodiment, the concentration is 0.05wt%.
In an embodiment of the present invention, the clay is selected from the group consisting of montmorillonite, bentonite, kaolin, hectorite, halloysite, and combinations thereof. In a preferred embodiment, the clay is bentonite. In an embodiment, the clay weight concentration is in the range of 0.05-2wt%. In a preferred embodiment, the concentration is 0.2-0.7wt%.
In an embodiment of the present invention, the resin is a formaldehyde resin. The formaldehyde resin can be any one of phenolic-formaldehyde resin (P-F resin), melamine-formaldehyde resin (M-F resin), and combinations thereof. In a preferred embodiment, the resin is P-F resin. In an embodiment, the resin weight concentration is in the range of 50-80wt%. In a preferred embodiment, the concentration is 60-70%. In a more preferred embodiment, the concentration is 70%.
In a most preferred embodiment of the present invention, the aqueous coating composition comprises a combination of HEC and P-F resin. The concentration of the combination of

HEC and bentonite is 0.08wt% and the concentration of P-F resin is 70%. The weight concentration of HEC is 0.05wt% and weight concentration of bentonite is 0.03wt%.
The coating composition can be prepared by any conventional method known to a person skilled in the art. In an embodiment, the coating composition is prepared by mixing the components and stirring to obtain a homogenous mix.
The present invention also provides an evaporative cooling pad coated with a composition comprising: (a) a material selected from the group consisting of at least a cellulose derivative, at least a clay, and combination(s) thereof; and (b) at least a resin.
In a preferred embodiment of the present invention, the evaporative cooling pad has a porous honeycomb structure. In another embodiment, the evaporative cooling pad has a porous rectangular structure. In another embodiment, the evaporative cooling pad has a porous circular structure. In yet another embodiment, the evaporative cooling pad has a porous oval structure. In yet another embodiment, the evaporative cooling pad has a porous diamond structure. In still another embodiment, the evaporative cooling pad has a porous irregular repeating structure.
The evaporative cooling pad of the present invention comprises a plurality of sheets made of cellulosic paper sheet. In an embodiment, the sheets are made of a biodegradable polymer. In an embodiment, the sheets are made of at least a biodegradable polymer and cellulosic paper sheet.
The composition coating the evaporative cooling pad is as substantially described in the present disclosure. In a most preferred embodiment, there is provided an evaporative cooling pad coated with a composition comprising: (a) a combination of HEC and bentonite having concentration of 0.08wt%; and P-F resin having concentration of 70%.
The present invention also provides a method of manufacturing evaporative cooling pad coated with a composition comprising: (a) a material selected from the group consisting of at least a cellulose derivative, at least a clay, and combination(s) thereof; and (b) at least a resin, said method comprising: (i) coating at least a sheet surface with the composition to obtain a coating having thickness in the range of 4-8µm; (ii) drying the sheet at a temperature

in the range of 100-130C for 2-15 seconds; (iii) corrugating the dried coated sheet; and (iv) curing the corrugated and dried sheet at a temperature in the range of 18-200C for 5-20 seconds.
The method further comprises adhesively binding a plurality of cured corrugated and dried sheets to obtain a stack of sheets. The coating for the evaporative cooling pad is as substantially described in the present disclosure.
In an embodiment, the method of manufacturing evaporative cooling pad comprises: (a) dipping the cellulosic sheet into a dipping trench containing the coating composition; (b) pre¬heating the impregnated sheets; (c) corrugating the impregnated dried sheets; (d) cutting the corrugated grooved sheets at specific angles; (e) heating the sheets for final curing and setting; (f) applying adhesive material on the sheets; (g) stacking a plurality of sheets on each other and heating to fix the adhesive; (h) cutting the dried stack of coated sheets into desired dimensions to form the evaporative cooling pads.
In a preferred, embodiment, the method of manufacturing evaporative cooling pad comprises: (a) administering a micron level coating of the coating composition by dipping the cellulose paper into a dipping trench containing the composition; (b) preheating the impregnated paper at 120C for 5-8 seconds; (c) corrugating the dry coated cellulose paper by passing it through a set of rollers and heated grooved rollers; (d) cutting the grooved paper line according to desired specification at specific angles; (e) heating the cut paper line at 180-200C for 8-12 seconds for final curing and setting; (f) adhering the cured paper using water emulsion based acrylic adhesive; (g) stacking the adhered paper sheets and hearing in oven to dry the adhesive; (h) cutting the dried stack of coated cellulose paper according to desired dimensions.
Fig. 1 provides an exemplary representation of the porous structure of the evaporative cooling pad of the present invention, surface of which is coated with the composition of the present invention.
Fig. 2 shows a depiction of the cooling effect of the evaporative cooling pad of the present invention. In a particular arrangement, there is a first cooling pad and second cooling pad,

separated by an air gap. Hot air flows from one side and is pushed through the evaporative cooling pads, which are percolated with water. The heat from the hot air is exchanged by the water, thus cooling the air on the other side of the pads.
Fig. 3 shows a close-up of the evaporative cooling pad surface. As can be seen, the surface of the pad (1) is coated with a composition (3) comprising HEC (0.05wt%), bentonite (0.03wt%) and P-F resin (2).
A test comparison of regular evaporative cooling pads and evaporative cooling pads of the present invention is provided below.

Feature Regular Present invention
Pad dimensions Side-605X315X40- Side-605X315X40-
(mm) 2 Nos. 2 Nos.
Back-605X495X40- Back-605X495X40-
1 No 1 No
Flue size (mm) 5 5
Pad weight dry Check the cellullose 180 179
(grams) pad dry weight and wet weight to check
Pad weight wet
400 387
(grams) the water absorbtion by the pad.
Water absorption by
220 208
pad (in grams)
Fitment with side Should be firm OK OK
/rear panel
Cooling Efficiency At least 60% 60% 68%
(%) in open
atmosphere
Cooling Efficiency At least 60% 75% 83%
(%) in controlled
condition
Cooling pad The cooling pad Completely wet Completely wet
wetness should get completely wet at 180V

As seen from the table above, the evaporative cooling pads of the present invention exhibit measurable significantly more cooling efficiency, in both open atmosphere and in controlled condition.
The evaporative cooling pad of the present invention advantageously has improved hydrophilicity (water absorption, adsorption, and retention capability); there is optimum water transmission through the cellulosic material via capillary action, thereby increasing the retention of water, and increasing heat exchange efficiency; higher tensile strength of the cooling pad and higher form retention due to the honeycomb porous structure.

We claim:
1. An aqueous coating composition for evaporative cooling pad comprising:
a. a material selected from the group consisting of at least a cellulose derivative,
at least a clay, and combination(s) thereof; and
b. at least a resin.
2. The composition as claimed in claim 1, wherein the cellulose derivative is selected from the group consisting of carboxy methyl cellulose (CMC), hydroxyl ethyl cellulose (HEC), hydroxypropyl cellulose, carboxymethyl cellulose, and combinations thereof.
3. The composition as claimed in claim 1, wherein the clay is selected from the group consisting of montmorillonite, bentonite, kaolin, hectorite, halloysite, and combinations thereof.
4. The composition as claimed in claim 1, wherein the resin is a formaldehyde resin.
5. The composition as claimed in claim 4, wherein the formaldehyde resin is selected from the group consisting of phenolic-formaldehyde resin (P-F resin), melamine-formaldehyde resin (M-F resin), and combinations thereof.
6. The composition as claimed in claim 1, wherein the cellulose derivative weight concentration is in the range of 0.02-1wt%; clay weight concentration is in the range of 0.05-1wt%; and resin weight concentration is in the range of 50-80wt%.
7. Evaporative cooling pad coated with a composition as claimed in claim 1.
8. The pad as claimed in claim 7, wherein the pad has a porous honeycomb structure.
9. The pad as claimed in claim 7, wherein the evaporative cooling pad comprises a plurality of sheets.
10. The pad as claimed in claim 7, wherein the sheet is cellulosic paper sheet.
11. A method of manufacturing evaporative cooling pad as claimed in claim 7, comprising:
a. coating at least a sheet surface with the composition as claimed in claim 1 to
obtain a coating having thickness in the range of 4-8µm;
b. drying the sheet at a temperature in the range of 100-130C for 2-15 seconds;

c. corrugating the dried coated sheet; and
d. curing the corrugated and dried sheet at a temperature in the range of 18-200C
for 5-20 seconds.
12. The method as claimed in claim 11, comprising adhesively binding a plurality of cured corrugated and dried sheets to obtain a stack of sheets.