FORM 2
THE PATENT ACT, 1970
(39 of 1970)
10 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: AN ANTI-MICROBIAL SKIM COAT DRY MIX COMPOSITION
APPLICANT:
UltraTech Cement Limited
of address
B wing, 2nd floor, Ahura Centre, Mahakali Caves road,
Andheri (East), Mumbai- 400 093, India.
PREAMBLE TO THE DESCRIPTION:
The following specification particularly describes this invention and the manner in
which it is to be performed.

FIELD OF THE INVENTION
The present invention relates to a skim coat dry mix composition. Specifically, the invention relates to a skim coat dry mix composition to be reconstituted in water for coating walls prior to painting and more particularly to a skim coat dry mix composition having anti-microbial properties.
BACKGROUND OF THE INVENTION
Preparing the walls for painting is always a tedious job and involves use of multiple coats of Plaster of Paris (POP) followed by painting in multiple coats to obtain the desired finish. This is not only expensive, but also time consuming since there is a drying time required between coats. Also, POP or conventional coats, on drying, often express grey colour of the underlying dark cement and this colour of the skim coat interferes with the true expression of the colour of the paint coat applied over it.
Skim coating is a texturing technique used to make a wall surface smooth. There are two types of skim coats - acrylic polymer based skim coats and cement based skim coats. Marketed skim coats are commonly acrylic polymer based which are applied to plastered walls to achieve optimal wall surface smoothness which are then ready for further application of paints/distempers.
Known skim coat is susceptible to growth of bacteria, yeasts and fungi. However, there are not very effective at preventing microbial growth on the dried skim coat. This results in the growth of microbes over time. It is known that scrubbing the skim coat to remove the microorganism may degrade the skim coating through abrasion. Furthermore, how quickly the bacteria are killed after contacting the skim coat is another important parameter in preventing the spread of disease.
Therefore, to address microbial growth in skim coat, anti-microbial skim coat composition has been designed in such a way that the end users feel to safe during entire process e.g., from bag opening, mixing, during & after application of putty on

the wall surface. The anti-microbial skim coat is capable of neutralization of microbes on skim coat surface to provide a safe environment to applicators/painters.
SUMMARY OF THE INVENTION
An object of the invention is to provide a skim coat composition having anti¬microbial properties.
Another object of the invention is to provide an anti-microbial skim coat providing excellent whiteness with higher coverage, adhesive strength & hydrophobic properties as well.
According to an embodiment of the present invention, there is provided a skim coat composition comprising, by weight of the composition,
a) (10 – 30) % of white cement,
b) (0.2 – 4) % of a vinyl acetate ethylene co-polymer,
c) (0.2 – 1) % of a methyl hydroxy ethyl cellulose,
d) (0.05-0.5) % of anti-microbial agent
e) (60 – 80) % of mineral filler; and
f) (0.5 – 5) % of a flexible hydrophobic polymer,
wherein the vinyl acetate ethylene co-polymer is prepared by combining (50 – 60) % of vinyl acetate and (40 – 50) % of ethylene.
In an aspect, the anti-microbial agent is a silver based anti-microbial agent.
DETAILED DESCRIPTION OF THE EMBODIMENTS
The invention summarized above and defined by the enumerated claims may be better understood by referring to the following description, which should be read in conjunction with the accompanying claims. This description of an embodiment, set out below to enable one to build and use an implementation of the invention, is not

intended to limit the invention, but to serve as a particular example thereof. Those skilled in the art should appreciate that they may readily use the conception and specific embodiments disclosed as a basis for modifying or designing other methods and systems for carrying out the same purposes of the present invention.
It is to be noted that, as used in the specification and the appended claims, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to a composition containing “a compound” includes a mixture of two or more compounds. It should also be noted that the term “or” is generally employed in its sense including “and/or” unless the content clearly dictates otherwise.
The expression of various quantities in terms of “%” or “% w/w” means the percentage by weight, relative to the weight of the total solution or composition unless otherwise specified.
The term “putty or skim coat” refers to a white cement-based polymer modified coating material used for building structures applied over different wall/surfaces to provides longer durability to paint.
The term “filler” used in reference are by products of cement industry which helps in controlling the final finish of the skim coat composition and is responsible for its unique natural bright & white color.

According to an embodiment of the present invention, there is provided a skim coat
dry
mix composition to be reconstituted in water for coating walls prior to painting. The
said skim coat composition exhibits anti-microbial property while exhibiting high
degree of whiteness which helps in getting the true tone of the topcoat paint applied
on it.
In an embodiment, the said composition comprises white cement which plays the role of an inorganic hydraulic binder providing strength and rigidity to the skim coat. It helps in adherence of the skim coat once applied to the wall surface. Preferably, the white cement is present in the range of (10 – 30) %, by weight of the composition.
According to an embodiment, the said composition comprises of vinyl acetate ethylene co-polymer. The vinyl acetate ethylene co-polymer is an organic re-dispersible powder binder which imparts flexibility, breathability, tensile adhesive properties and abrasion resistance properties to the skim coat. This results in the skim coat composition to be more adhesive towards the wall and hence there is no cracking of the paint. Preferably, the vinyl acetate ethylene co-polymer is present in the range of (0.2 – 4) %, by weight of the composition. In a preferred embodiment, the vinyl acetate ethylene co-polymer contains (50 – 60) % of vinyl acetate and (40– 50) % of ethylene, by weight of the vinyl acetate ethylene co-polymer.
In an embodiment, the composition comprises of methyl hydroxy ethyl cellulose which provides workability to the skim coat composition thereby improving the ease and smoothness of working with the skim coat dry mix during its application. Additionally, the methyl hydroxyl ethyl cellulose has hydroxyl group present in it which contributes to water retention property of the present skim coat composition thereby avoiding the need to cure the plastered wall after application of the skim coat. This cuts down on a process step and leads to saving of water as well as time. Preferably, the methyl hydroxy ethyl cellulose is present in the range of (0.2 – 1) %, by weight of the composition.

the methyl hydroxy ethyl cellulose contains (93-95) % of methyl hydroxy ethyl cellulose active content and (5-7) % ash content, by weight of the methyl hydroxy ethyl cellulose.
In another embodiment, the skim coat composition comprises of mineral filler. The mineral filler fills in all the pores of the walls and ceiling and provides a white, smooth and dry surface for painting and contributes to increasing the life of the painted surface. Preferably, the mineral filler is present in the range of (60 – 80) %, by weight of the composition.
In an embodiment, the mineral filler is selected from the group consisting of dolomite, calcite, hydrated lime or a mixture thereof. Usage of all these alternatives of mineral filler and others are considered to be within the scope of the present invention.
Preferably, finer particles of calcite are used in the skim coat composition wherein the size of the calcite particles is (8-15) microns. Due to the smooth finish, paint is not lost in uneven surface areas or undulations on the wall surface thereby decreasing the volume of paint required for painting on the skim coated wall; thereby further reducing the costs to the customer. Additionally, the high whiteness of the wall surface results in solar thermal infer-red reflectivity. It is a known phenomenon that products utilizing reflective technology are likely to have a longer service life because of the lower surface temperatures which in turn lessen the chemical and atmospheric degradation and also lessen the expansion and contraction. The lower surface temperature will also keep the interiors of the house cooler during hot days.
In an embodiment, the skim coat composition comprises of a flexible hydrophobic polymer. This flexible polymer lends hydrophobicity to the skim coat composition which in turn makes the composition water resistant once applied on the plastered wall surface and prevents water ingress from both inside and outside the wall, thus protecting the wall surface from water even during washing of the surface. Preferably, the flexible hydrophobic polymer is present in the range of (0.5 – 5) %, by weight of

the composition. In an embodiment, the flexible hydrophobic polymer is prepared by mixing (40 – 50) % of vinyl acetate and (50 – 60) % of ethylene.
In an embodiment, the skim coat composition comprises of an anti-microbial agent in the range of 0.05-0.5%, by weight of the composition. Preferably, the anti-microbial agent is a silver ion based anti-microbial agent. The silver ion based anti-microbial agent is non-leachable inorganic in nature which gives anti-microbial property and does not degrade with time. White cement hydraulic binder is inorganic in nature and provides hard binding and rigidity to the final coat.
In an embodiment, the silver based anti-microbial agent is silver sulphate. The silver sulphate is stored in a reservoir which is responsible for the formation of chelate like structures in the absorption of polar & charged silver ions and release them when needed. Silver sulphate is released in a controlled manner through a precipitated silica reservoir into the skim coat mixture.
In an embodiment, the components of the skim coat composition are dry mixed in their specific proportions to yield a dry mix composition which only needs to be reconstituted with a specific amount of water, by the user, at the time of skim coating a plastered wall surface. The components are mixed at an ambient temperature and pressure. It makes the product an easy-to-use and do-it-yourself skim coat composition, obviating the need for skilled workmen to do the work of skim coating prior to painting. Also, the high costs associated with using POP or acrylic polymer based skim coats for plastering walls are overcome.
As a whole, the skim coat composition of the present invention, supports wall breathability, provides high whiteness and coverage and allows water vapour from the wall to escape without causing damage to the topcoat paint. Also, due to the absence of acrylic polymers in the present composition, there are no volatile organic compounds which pollute the environment.
EXAMPLES

Advantages and benefits of the skim coat composition according to the embodiments of the present invention would become more apparent from the below experimental details to a person skilled in the art.
EXAMPLE 1:
a) 100 g of white cement was mixed with 541 g of dolomite, 250 g of calcite and 70 g of hydrated lime filler, by weight of the composition.
b) To this dry mix, 10 g of vinyl acetate ethylene copolymer, 25 g of flexible hydrophobic polymer and 4 g of methyl hydroxyl ethyl cellulose, were added, by weight of the composition.

c) A skim coat dry mix composition having anti-microbial properties was less than 99% obtained.
d) This dry mix was reconstituted in water and the paste was coated on the walls prior to painting.
EXAMPLE 2:
a) 100 gof white cement was mixed with 540.5 g of dolomite, 250 g of calcite and 70
gof hydrated lime filler, by weight of the composition.
b) To this dry mix, 10 gof vinyl acetate ethylene copolymer, 25 gof flexible
hydrophobic polymer and 4 gof methyl hydroxyl ethyl cellulose, 0.5 g of anti¬
microbial agent, were added, by weight of the composition.
c) A skim coat dry mix composition having anti-microbial properties was approx. 99% obtained.
d) This dry mix was reconstituted in water and the paste was coated on the walls prior to painting.
EXAMPLE 3:

a) 100 g of white cement was mixed with 540 g of dolomite, 250 g of calcite and
70gof hydrated lime filler, by weight of the composition.
b) To this dry mix, 10 g of vinyl acetate ethylene copolymer, 25 g of flexible
hydrophobic polymer and 4 g of methyl hydroxyl ethyl cellulose, 1 g of anti-microbial
agent, were added, by weight of the composition.
c) A skim coat dry mix composition having anti-microbial properties was more than 99.9% obtained.
d) This dry mix was reconstituted in water and the paste was coated on the walls prior to painting.
Table 1 provides the properties of the skim coat composition of examples 1-3.

Parameter Name Of materials Example-1 (Without Anti-microbial additive) Example-2
(with 0.05 %
anti-microbial
additive) Example-3 (with 0.1 % anti-microbial additive)
% composition White Cement 10 10 10

vinyl acetate ethylene copolymer, 1 1 1

Flexible hydrophobic polymer, vinyl acetate, high ethylene Polymer 2.5 2.5 2.5

Methyl Hydroxyl ethyl cellulose 0.4 0.4 0.4

Mineral Fillers like calcite, dolomite 86.1 86.05 86.0

Silver ion based antimicrobial additive 0.0 0.05 0.1
Results Tensile Adhesion strength @ 28 Days (N/mm2) 1.15 1.18 1.2

Water Capillary absorption, 30 min, 28 days (ml) 0.1 0.1 0.1

Accelerated weathering (QUV) test @500 hrs.-Durability test 0.43 0.44 0.45

Virus Kill (Reduction %) (Contact duration 2 hours) (Virus Name -MS2 Bacterio phage) Test Protocol-ISO21702:2019 95.60 99.22 99.93

Virus Kill (Reduction %)
(Contact duration 24 hours)
(Virus Name-MS2 Bacteriophage) Test
Protocol-ISO21702:2019 96.63 99.51 >99.98

Microbial Kill (%Reduction)
Test Bacteria : Staphylococcus aureus ATCC
6538
Test Protocol-JSI Z 2801 : 2010 95.74 99.31 >99.99

Microbial Kill (%Reduction)
Test Bacteria: Escherichia coli ATCC 8739
Test Protocol- JSI Z 2801 : 2010 96.33 99.02 99.97

Anti-Fungus test: Mixed spore suspension of aspergillus niger ATCC 9642, Penicillium funicolosum ATCC 11797 & Aurobasidium ATCC 15233 Test Protocol- ASTM D 5590:2017 (Trace of growth-<10%) 0 No Zone 0 No Zone

Anti-Algal Test: Algal defacement 1 by
ASTM D 5589-09 (2013)
Test Protocol- ASTM D 5589-09 0 No Zone 0 No Zone 0 No Zone
The Cement contents (10%), vinyl acetate ethylene copolymer contents (1%), hydrophobic polymer (2.5 %), MHEC contents (0.4%), Mineral Fillers like calcite, dolomite contents (approx. 86%) are similar & used silver ion based antimicrobial additive is 0.00 %, 0.05 % & 0.1 % respectively for example 1,2 &3. The outcomes are as under
1) When no silver ion based antimicrobial additive is used then skim coat dry mix composition having less than 99% anti-microbial properties (Example 1).
2) In Example 2, when 0.05% silver ion antimicrobial additive is used then skim coat dry mix composition achieved approx. 99% anti-microbial properties.
3) The example 3, when 0.1% silver ion based antimicrobial additive is used, the skim coat dry mix composition having excellent anti-microbial properties & was recorded more than 99.9%.
4) Other technical properties like Tensile Adhesion strength @ 28 Days, Water Capillary absorption, 30 min, @ 28 days & Accelerated weathering (QUV) test @500 hrs. test results were found almost same for all experimental examples 1, 2 & 3 respectively.
From the given experimental data in table 1, it is evident that the claimed composition is capable of neutralizing/killing more than 99.9 % virus, bacteria & other microbes.

[021] 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.

We claim:
1) An anti-microbial a skim coat composition comprising, by weight of the
composition,
a) (10 – 30) % of white cement,
b) (0.2 – 4) % of a vinyl acetate ethylene co-polymer,
c) (0.2 – 1) % of a methyl hydroxy ethyl cellulose,
d) (0.05-0.5) % of anti-microbial agent
e) (60 – 80) % of mineral filler; and
f) 0.5 to 5 % of flexible hydrophobic polymer (vinyl acetate)
2) The composition as claimed in claim 1, wherein the vinyl acetate ethylene co-
polymer contains (50 – 60) % of vinyl acetate and (40 – 50) % of ethylene, by weight
of the vinyl acetate ethylene co-polymer.
3) The composition as claimed in claim 1, wherein the methyl hydroxy ethyl cellulose contains (93-95) % of methyl hydroxy ethyl cellulose active content and (5-7) % ash content, by weight of the methyl hydroxy ethyl cellulose.
4) The composition as claimed in claim 1, wherein said anti-microbial agent is silver sulphate.
5) The composition as claimed in claim 1, wherein the flexible hydrophobic polymer comprises of (40 – 50) % of vinyl acetate and (50 – 60) % of ethylene

4) The composition as claimed in claim 1, wherein the mineral filler is selected form the group comprising of dolomite, calcite, hydrated lime or a combination thereof.
5) The composition as claimed in claim 1, wherein the size of the calcite is (8-15) microns.

6) The composition as claimed in claim 1, having an adhesive strength of 1.08 1.20 Mpa.