DESC:
FIELD OF THE INVENTION
The present disclosure relates to a coating composition for various paper-based products. More particularly, the present disclosure relates to anti-microbial coating compositions for various paper substrates.

BACKGROUND OF THE INVENTION
There is a growing need for paper-based paraphernalia having surface anti-microbial properties. Applying anti-microbial coatings on paper-based substrates however poses several challenges. Quaternary ammonium compounds have been a preferred class of compounds that is used for rendering anti-microbial activity to various types of substrates and surfaces. However, some of the compounds in this class for example, benzalkonium chloride when used as a stand-alone active in coating compositions for paper-based substrates, it tends to increase the water absorption capacity of the substrate (undesirable feature). Further, these actives also cause foaming during application thereby posing another set of challenges during processing.

WO2017216602A1 relates to paper sheets and paper hygiene products that provide anti-microbial properties by employing antibacterial, anti-fungus and/or antiviral agents being added to the paper sheet or product. The antibacterial agents that can be employed include ammonium quaternary compounds and its derivatives, triclosan (halogenated phenols) and its derivatives, metals and its oxides, cyclodextrin molecules, molecules of iodine, hydrogen peroxide, Bromocresol green sodium salt, Hexa trichlorphon, sodium chloride, potassium alum, chlorine, chlorhexidine, Benzalkonium chloride among others.

CN103988842A discloses a bactericidal composition for paper products. The bactericidal composition comprises containing amino polymer antibacterial agent and alcohols, described is at least one of guanidine like polymer and quaternary ammonium salt polymer containing amino polymer antibacterial agent.

JPH00892013A discloses antimicrobial composition for industrial purposes, applicable to industrial raw materials such as textiles, pulp or the like and products therefrom, comprising a combination of benzalkonium chloride with a p- hydroxybenzoic acid ester. The weight ratio of the benzalkonium chloride to the p-hydroxybenzoic acid ester is preferably 100/1-1/1, particularly 50/1-10/1.

JP2001288697A relates to an antibacterial paper coated with an acrylic binder resin on the surface of paper. A 5 to 10% aqueous solution of an antibacterial agent comprising a hot water extract of cereals, alkyldimethyl-benzalkonium chloride, lauryl-imino-dipropionic acid, and polyoxy-propylene glycol has been disclosed.

CN107059477A discloses a preparation method of antibacterial paper containing a quaternary ammonium salt antibacterial agent, and belongs to the technical field of functional packaging paper. The quaternary ammonium salt antibacterial agent is a quaternization styrene-maleic anhydride copolymer.

CN1548649A discloses a kind of antibiotic paper for daily use, it contains at least an antiseptic, it is characterized in that: described paper for daily use also contains at least a retention agent. The antiseptic is glutaraldehyde, hydrocarbon ammonium salt, the own pyridine of Ammonium Acetate, benzalkonium chloride, benzalkonium bromide, polyquaternium, isothiazolinone, oxirane, tetraphenylboron sodium or formaldehyde.

While Benzalkonium chloride (BKC) have been known to be used as an antimicrobial coating on paper, it is known to adversely impact the surface quality of paper particularly by exacerbating its water absorptiveness (indicated by higher Cobb value). Accordingly, there, there remains a need for a coating composition on paper sheets that not only provides improved microbial kill but lowers the Cobb value of the paper sheets.

OBJECTS OF THE INVENTION
The object of the present disclosure is to provide an antimicrobial coating composition for paper and paperboards.

Another object of the present disclosure is to provide a coating composition for paper-based products that avoid processing issues like excessive foaming during the application.

Yet, another object of the present disclosure is to provide a coating composition that does not alter the surface characteristics of the paper-based products upon its application.

Yet another object of the present disclosure is to provide a coated paper-based product that exhibits superior surface antimicrobial effect.

Yet another object of the present disclosure is to provide an antimicrobial coated paper product which exhibits reduced water absorptiveness.

The present disclosure relates to an antimicrobial coating composition for coating on paper sheets comprising Benzalkonium chloride as an antimicrobial agent in combination with titanium dioxide and a solvent.

SUMMARY OF THE INVENTION
In one aspect, there is provided an antimicrobial coating composition for a paper substrate comprising:
at least one organic antimicrobial agent;
at least one inorganic antimicrobial agent;
a solvent; and
optionally, at least one excipient/additive selected from the group that includes but is not limited to a binding agent; a paper sizing agent and the like;
wherein the ratio of the amount of said organic anti-microbial agent to said inorganic antimicrobial agent ranges from about 1:1 to about 1:6.

In a second aspect of present invention, there is provided an antiviral coating composition for a paper substrate comprising:
at least one organic antiviral agent;
at least one inorganic antiviral agent;
a solvent; and
optionally, at least one excipient/additive selected from the group that includes but is not limited to a binding agent; a paper sizing agent and the like;
wherein the ratio of the amount of said organic anti-viral agent to said inorganic antiviral agent ranges from about 1:1 to about 1:20.

In a third aspect of present invention, there is provided an antibacterial coating composition for a paper substrate comprising:
at least one organic antibacterial agent;
at least one inorganic antibacterial agent;
a solvent; and
optionally, at least one excipient/additive selected from the group that includes but is not limited to a binding agent; a paper sizing agent and the like;
wherein the ratio of the amount of said organic anti-bacterial agent to said inorganic antibacterial agent ranges from about 1:1 to about 1:6.

In fourth aspect of the present disclosure, there is a provided a coated paper substrate with Cobb value below 35, preferably below 30 and most preferably below 25. The GSM of the paper substrate may vary between 30-90 GSM, preferably between 50 to 70 GSM. The coated substrate after aging typically exhibits log kill of at least 2, preferably above 2.5, and most preferably above 3.00 at 15 minutes of exposure time.

Other aspects, advantages, and salient features of the disclosure will become apparent to those skilled in the art from the following detailed description.

BRIEF DESCRIPTION OF ACCOMPANIED DAWINGS
The above and other aspects, features and advantages of the embodiments of the present disclosure will be more apparent in the following description taken in conjunction with the accompanying drawings, in which:

FIG. 1 illustrates (A) Schematic representation of ISO 18184 protocol for evaluating antiviral activity of coated samples. (B) Plaque formation (clearance) on mammalian host cell (purple) at different dilutions of virus suspension.

FIG. 2 illustrates schematic representation of ISO 20743 protocol – for antibacterial activity.

FIG. 3 illustrates empirical process outline according to present invention.

Persons skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and may have not been drawn to scale. For example, the dimensions of some of the elements in the figure may be exaggerated relative to other elements to help to improve understanding of various exemplary embodiments of the present disclosure. Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures.

DETAILED DESCRIPTION
The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the present disclosure.

It is to be understood that the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

All terms (including technical and scientific terms) used herein have the same meaning as commonly understood by ordinary skill in the art to which various embodiments belong.

It will be further understood that the terms "comprise" and/or "comprising" used herein specify the presence of stated features, steps, components, but do not preclude the presence or addition of one or more other features, steps, components, and/or groups thereof.

Cobb value used in the context of the present disclosure means the calculated mass of water absorbed in a specified time by 1 m2 of paper or paper board under specified condition. The measurement of Cobb value is done as per standard ISO 535.

The expression “substrate” in the context of the present disclosure means paper or paperboard substrate that includes any paper or cardboard items, including packaging and packaging materials. Paper or paperboards can be sized or un-sized.

The expression "anti-microbial" in the context of the present disclosure means anti-bacterial or anti-viral or a combination of both.

One of the embodiments of present invention relates to an antimicrobial coating composition for a paper substrate comprising:
at least one organic antimicrobial agent;
at least one inorganic antimicrobial agent;
a solvent; and
optionally, at least one excipient/additive selected from the group that includes but is not limited to a binding agent; a paper sizing agent and the like;
wherein the ratio of the amount of said organic anti-microbial agent to said inorganic antimicrobial agent ranges from about 1:1 to about 1:6.

In a preferred embodiment, the amount of the organic anti-microbial agent ranges from about from 0.1 wt% to 0.3 wt% and the amount of the inorganic anti-microbial agent ranges from about 0.15-0.9 wt% of the coating composition.

Another embodiment of present invention relates to an antiviral coating composition for a paper substrate comprising:
at least one organic antiviral agent;
at least one inorganic antiviral agent;
a solvent; and
optionally, at least one excipient/additive selected from the group that includes but is not limited to a binding agent; a paper sizing agent and the like;
wherein the ratio of the amount of said organic anti-viral agent to said inorganic antiviral agent ranges from about 1:1 to about 1:20.

In a preferred embodiment, the amount of the organic anti-viral agent ranges from about from 0.1 wt% to 0.75 wt% and the amount of the inorganic anti-viral agent ranges from about 0.15-2.0 wt% of the coating composition.

Yet another embodiment of present invention relates to an antibacterial coating composition for a paper substrate comprising:
at least one organic antibacterial agent;
at least one inorganic antibacterial agent;
a solvent; and
optionally, at least one excipient/additive selected from the group that includes but is not limited to a binding agent; a paper sizing agent and the like;
wherein the ratio of the amount of said organic anti-bacterial agent to said inorganic antibacterial agent ranges from about 1:1 to about 1:6.

In a preferred embodiment, the amount of the organic anti-bacterial agent ranges from about from 0.1 wt% to 0.3 wt% and the amount of the inorganic anti-bacterial agent ranges from about 0.15-0.9 wt% of the coating composition.

Typically, the organic antimicrobial/ antiviral/ antibacterial agent is at least one quaternary ammonium compound selected from the group that includes but is not limited to benzalkonium chloride, benzethonium chloride, methylbenzethonium chloride, cetalkonium chloride, cetylpyridinium chloride, cetrimonium, cetrimide, dofanium chloride, tetraethylammonium bromide, didecyldimethylammonium chloride and domiphen bromide. Optionally, the organic antibacterial agent may also include at least one anti-microbial agent selected from the group that includes but is not limited to chlorhexidine or any salt thereof.

In a preferred embodiment, the inorganic anti-microbial/ antiviral/ antibacterial agent may be at least one selected from the group that includes but is not limited to silver, zinc, copper, titanium and the like.

Solvents employed in the present composition can be a non-aqueous solvent or an aqueous solvent depending upon the type of paper or paperboard to be coated. Examples of non-aqueous solvent include but are not limited to varnish. Examples of aqueous solvents include but are not limited to water.

In a preferred embodiment, the coating composition comprises Benzalkonium chloride as an organic antimicrobial/ antiviral/ antibacterial agent in combination with titanium dioxide as an antimicrobial/ antiviral/ antibacterial agent and water as solvent.

In another aspect of the present disclosure, there is a provided a coated paper substrate with Cobb value below 35, preferably below 30 and most preferably below 25. The GSM of the paper substrate may vary between 30-90 GSM, preferably between 50 to 70 GSM. The coated substrate after aging typically exhibits log kill of at least 2, preferably above 2.5, and most preferably above 3.00 at 15 minutes of exposure time.

In some of the embodiments, the coated substrate in accordance with the present disclosure exhibits anti-microbial as well as anti-viral as well as anti-bacterial properties.

In one of the embodiments the substrate is paper with 50-70GSM.

Based on the end use of paper or paperboard taken as substrate, its surface may also be coated with varnish to have properties like gloss, water repellency and smoothness.

The present disclosure has been illustrated by way of the following non-limiting examples.

Examples 1. Preparation of the antimicrobial composition
A solution of starch in solvent was prepared by heating to boiling temperature in case of aqueous formulation (heating is not required in case of non-aqueous solvent) under stirring until clear solution was obtained. Cooled to 50°C to add Basoplast 8903 and stirred well. To this active/mixture of actives was added and further stirred at high speed. In case of insoluble material, a dispersion of the same was prepared by high speed homogenizer (3000rpm) for at least an hour. This formulation was as such used for paper coating.

Examples 2. Antimicrobial properties of the disclosed composition
Table 1 shows anti-microbial properties of the coating composition with instantaneous kill of above 2 log over a period of 18 months without affecting any paper properties.

Table 1
Properties Control Invention
Construct paper without antimicrobial composition coating on it
antimicrobial composition coated paper
Properties GSM (±2.5%) 56 56
COBB 20-22 <25
Whiteness 140.71 140.71
Brightness 89.23 89.23
Opacity 90.39 90.39
Ink penetration (Octane Ball/Octane Flo) 46/54 46/54
Antimicrobial activity NO Yes

Parameters Conditions Unit
Ingredient Technology Actives BKC+TiO2
Dosage Kg/MT of paper BKC=0.75, TiO2= 2
Paper properties Cobb GSM 22-24
Tappi Cobb (105°C 72 h) GSM 20-21
ISO Cobb (80°C 65 % RH 144 h) GSM 50

All values stated above are an average of 10 measurements for each parameter.

The paper substrate taken for application of this coating composition is un-sized paper.

Some of the working and non-working examples in respect of the anti-viral composition as disclosed in one of the embodiments are provided in below Table 2 and 3:
Table 2
Ingredients Lab scale
Quantity (gms for 100gm formulation in water)
Binding Agent
Oxidised starch (100% solids) 9-12
Sizing Agent
Basoplast 8903 (as received) 0.9-1
Organic Active Benzalkonium Chloride (100% solids) 0.1-0.75
Inorganic Active
TiO2 (100% solids) 0.15-2

Table 3
Ingredient NW1
Wt% NW2
Wt% NW3
Wt% NW4
Wt% W1
Wt% W2
Wt%
Oxidised Starch 11 11 11 11 11 11
Sizing Agent 1 1 1 1 1 1
Water 86.4 87 87.7 87.4 85.75 85.25
BKC 1.6 1 0.3 - 0.75 0.75
TiO2 - - - 0.6 1.5 2
Total 100 100 100 100 100 100
Cobb* expressed in GSM >55 54 34 16-18 24-25 19-20
Log kill** >4 >3.5 0.3 0 >3 3.11

Some of the working and non-working examples in respect of the anti-microbial/ anti-bacterial composition as disclosed in one of the embodiments are provided in below Table 4 and 5:
Table 4
Ingredients Lab scale
Quantity (gms for 100gm formulation in water)
Binding Agent
Oxidised starch (100% solids) 9-12
Sizing Agent
Basoplast 8903 (as received) 0.9-1
Organic Active Benzalkonium Chloride (100% solids) 0.1-0.30
Inorganic Active
TiO2 (100% solids) 0.15-0.9

Table 5
Ingredient NW1
Wt% NW2
Wt% NW3
Wt% NW4
Wt% W1
Wt% W2
Wt% W3
Wt%
Oxidised Starch 11 11 11 11 11 11 11
Sizing Agent 1 1 1 1 1 1 1
Water 86.4 87 87.7 87.4 87.4 87.1 87.25
BKC 1.6 1 0.3 - 0.3 0.3 0.15
TiO2 - - - 0.6 0.3 0.6 0.6
Total 100 100 100 100 100 100 100
Cobb* expressed in GSM >55 54 34 16-18 36-37 30 22-25
Log kill** >4 >3.5 0.3 0 3.5-4.5 3.5-4.3 3.2-4.1

NW1 to NW4 -Non working coating formulation 1-4
W1 to W3 – Working formulation 1-3
*Measurement as per ISO 535
**Measurement as per ISO 20743
*&** are the values for the paper before aging.

Working example ratio: 1:1 to 1:6.

From the Table 3 and 5 it is evident that BKC alone when taken as active showed very good activity against virus or bacteria. But being a surfactant, it also increased the water absorption of paper. As the concentration of BKC was decreased water absorption also decreased in direct proportion. But this was accompanied by a decline in its activity against bacteria. Similarly, when TiO2 alone was taken as active, there was no direct effect on Cobb but the activity against bacteria was also poor. When a combination of two was taken it was observed that even at lower dosage of BKC, it not only showed good activity against Bacteria, (gave a log kill of >3) but also unexpectedly lowered the Cobb value.

Example 3: Validation of Antiviral activity with relevant data along with protocol used for generation of data (Table 8)

In-house Anti-bacterial testing method for Notebook cover:
The assay describes the method for measuring anti-bacterial activity on porous surfaces of treated products against specified Bacteria.
1. Four sections of 3 cm X 3 cm were cut and placed in separate sterile plate (two for E. coli and two for S. aureus). For notebook cover, shiny surface (UV varnished) was tested.
2. Bacterial cell suspension was spotted on the one sample and 2nd piece was placed on top to spread bacterial cells between two surfaces (between two Shiny surfaces in case of Notebook cover)
3. Samples were incubated at 35°C for required contact time.
4. Neutralizer was added to sample at the end of desired contact time period. Bacteria were collected, serially diluted and live bacteria were enumerated on Trypicase Soy Agar plates.

In-house Anti-bacterial testing method for Paper:
The assay describes the method for measuring anti-bacterial activity on porous surfaces of treated products against specified Bacteria
1. Papers were cut in to 3 cm X 3 cm sections.
2. Bacterial cell suspension was spotted on cut papers
3. Samples were incubated at 35°C for required contact time.
4. Neutralizer was added to sample at the end of desired contact time period.
5. Bacteria were collected, serially diluted and surviving bacteria were enumerated on Trypticase Soy Agar plates.

External Anti-bacterial testing method for Paper:
The assay describes the method for measuring anti-bacterial activity on porous surfaces of treated products against specified Bacteria.

Name of Test: Determination of Antibacterial Activity of Textile products by ISO 20743: 2013(E); Quantitative Method*
Test Conditions:
Sterilization of Sample: autoclaving
Neutralizer used: Buffered Saline with Triton X 100 - 0.01 %
Contact Time: 15 minutes
Contact Temperature: 37° C
Media and Reagent: Soyabean-casein digest agar
*Modified with respect to time.

Anti-viral testing for Non-porous surface:
The assay describes the method for measuring antiviral activity on plastics and other nonporous surfaces of antiviral-treated products against specified viruses.

Test Method: ISO 21702 (Measurement of antiviral activity on plastics and other non-porous surfaces) Non-porous paper of size 50mm

Outline of Test Method:
A test suspension of the SARS-CoV-2 virus was inoculated onto non-porous test and its respective control surface followed by covering with a cover film. The surfaces loaded with virus inoculum were maintained at specified temperature (25 °C ± 1 °C) for a contact period of 15 minutes maintaining required humidity. At the end of the contact time remaining infectious virus particles were recovered individually from Control & test surfaces by washing the surfaces with medium. Quantification of recovered surviving organisms (infectious virus particles) was done by plaque assay. As prescribed in guideline assay was performed in triplicate using 3-test specimen for each step.

Anti-viral testing for paper (IRSHA):
The assay describes the method for measuring antiviral activity on porous textiles surfaces of antiviral-treated products against specified viruses.

Test Method: ISO 18184: 2014*

Outline of Test Method: A test suspension of the SARS-CoV-2 virus was inoculated onto Control and antimicrobial treated-test paper surface. The surfaces loaded with virus inoculum were maintained at specified temperature (25 º C ± 1 º C) for a contact period of 15 minutes. At the end of the contact time remaining infectious virus particles were recovered individually from onto Control and antimicrobial treated-test paper surface by washing the surfaces followed by vortex and agitation in neutralizing medium. Quantification of recovered surviving organisms (infectious virus particles) was done by plaque assay. The assay was performed in triplicate using 3 test specimens for each step.
*Modified with respect to contact time

Anti-viral testing for paper (BTS Lab):
This International Standard specifies testing methods for the determination of the antiviral activity of the textile products. The textile products include woven and knitted fabrics, fibres, yarns, braids using Enveloped virus, an influenza virus, which is an infective virus in humans that causes respiratory tract infection.
Test Method:
ISO 18184: 2019; Determination of antiviral activity of textile products*
Test Virus: Human Coronavirus HCoV-229E
Test Procedure:
1. Test Fabrics and Control Fabrics were inoculated with 0.2 ml of virus suspension in triplicate sets. One triplicate set of Control fabric was terminated immediately after adding virus suspension. Remaining sets were incubated at 37°C for 15 minutes & 2 hours in CO2 incubator.
2. After the contact duration, test and Control fabrics were terminated using wash out solution. Virus titre of wash out solution was determinate using TCID50 Method
*Method modified with respect to contact time.

Anti-viral testing for multiple touch in Paper:
The assay describes the method for measuring Anti-viral activity on Paper on multiple inoculation.

Test Method: ISO 18184: 2014*

Test Conditions: Infectivity titre test: TCID50 method

Sample Re-Infection Procedure:
Paper samples were inoculated with virus three times, incubated for 15 minutes followed by re-inoculation and incubation for 15 minutes and re-inoculation and incubation to illustrate the effect of multiple inoculations on same surface over a period of time.

Virus strains and host cells:
Test Virus: Influenza A virus (H3N2): A/Hong Kong/8/68: ATCC VR-1679
Host Cell: MDCK cell ATCC CCL-34
Infectivity titre test: TCID50 method
*Modified with respect to contact time

Antimicrobial efficacy study: An Overview of Methods used:
ISO 18184 is a standard test to evaluate antiviral efficacy of Fabric and other similar porous material. It is performed with Influenza virus (enveloped virus - similar to SARS CoV-2) and Feline Calicivirus. (non-enveloped virus, harder to kill than enveloped viruses). This test is described in Figure 1.

ISO 20743 is a standard test similar to ISO 18184 to evaluate antibacterial activity of samples. It is performed using Staphylococcus aureus (Gram positive bacteria) and Klebsiella pneumonia (Gram negative bacteria). This test is described in Figure 2.

Validation of improvement in surface antimicrobial activity
Test on Porous & Non-porous Paper & Paperboard has been carried out against stringent bacteria and viruses (E. coli, S. aureus, K. pneumonia, Influenza A, COVID 19 (SARS-CoV-2)) through standard methods. Thus, representing the all ranges of bacteria and viruses.

Comparative results with other Quaternary compounds other than BKC (refer Table 6)

Anti-microbial activity against E. coli:
Table 6

Actives used % used in coating formulation Contact time Log Kill Cobb value (GSM)

Chlorhexidine Gluconate (CHG) 0.33% 30 min 2.5 24.7
Chlorhexidine Gluconate (Aged) 0.33% 30 min 0.1 64
Benzethonium chloride 1.00% 30min >4 57.4
0.30% 30min 0.3 49
Biosafe Quaternary Siloxane 1% 30 min 0.01 54.3
Cetrimide 2.00% 30 min >3.9 52
Quaternary ammonium compounds, benzyl-C12-16-alkyldimethyl, chlorides+Dodecylguanidine monohydrochloride 2.00% 3 hrs 1.2 24
CHG+Cetrimide 1.4%+0.6% 30 min >3.9 60
Benzalkonium chloride+Benzthonium chloride 0.15%+0.15% 30 min <1 36.9
AgCl2 & TiO2 reaction mass with Benzalkonium chloride 1%+1% 30 min 0.3 28.3
Silver with lipid vesicle technology+Benzalkonium chloride 0.5%+0.6% 30 min 0.3 28.3
CHG + TiO2 0.6%+0.6% 30 min 2.3 24

Non-Working examples outside the ratio range of BKC: TiO2 (Table 7)

Table 7
Sl No. BKC%+TiO2% used in coating formulation (Ratio) Cobb Value (gsm) E. coli S. aureus
30mins 2 hrs 30mins 2 hrs
1 0.15% + 0.6% (1:4) 20-23 2.7 4.1 2.8 3.2
2 0.15% + 0.6% (after aging – ISO standard) 45-50 0.4 - 0.2 -
3 0.3%+ 0.6% (1:2) 28-30 2.9 4.3 3.2 3.5
4 0.3%+ 0.6% (after aging – ISO standard) 52-55 0.8 - 1 -
5 0.3% + 0.15% (2:1) 30-31 0.3 - 0.3 -
6 0.3% + 0.3% (1:1) 36-37 3.3 3.5 4.5 4.5
7 0.2% + 0.6% (1:3) 29-31 2.1 - 2.5 -
8 0.15% + 0% 19-21 0 0.1 0.2 0

Table 8
Active used in coating Exposure time K. Pnuemoniae (ISO 20743:2013E) Influenza A (ISO 18184-2014) COVID 19 (SARS-CoV-2) (ISO 18184-2014) Human Coronavirus HCoV-229E
Supported Silver on inorganic proprietary base dispersed in acrylic emulsion 15 mins 2.29 (99.49%) 3.78 (99.98%) <1 (<90%) 0.23 (39.74)
2 Hrs 2.83 (99.85%) 4.6 (99.99%) - 0.37 (57.34%)
Supported Silver on inorganic proprietary base dispersed in acrylic emulsion - After aging (ISO std) 15 mins 2.55 (99.72%) 3.53 (99.97%) - -
2 Hrs 2.59 (99.74%) 3.8 (99.98%) - -
Supported Silver on inorganic proprietary base dispersed in acrylic emulsion - Multiple touch 15 mins - 2.36 (99.56%) - -
BKC 0.75% + TiO2 2% 15 mins 2.01 (99%) 3.11 (99.92%) <1 (<90%) 3.11 (99.92%)
2 Hrs 2.36 (99.58%) 3.43 (99.96%) - 4.1 (99.99%)
BKC 0.75% + TiO2 1.5% - After aging (ISO std) 15 mins 2.43 (99.63%) 2.92 (99.87%) - -
2 Hrs 2.4 (99.61%) 3.06 (99.91%) - -
BKC 0.75% + TiO2 1.5% - Multiple touch 15 mins - 3.01 (99.9%) - -
BKC 0.2% + TiO2 0.6% 15 mins - - 20.58% -
2 Hrs - - - -
Classmate Paperboard (Porous side) 15 mins - - 0.49 (67.49%) -
Classmate Paperboard (laminated side) 15 mins - - 0.63 (76.67%) -
Classmate Paperboard (UV varnish + BKC) 15 mins 1.67 (97.87%) 2.07 (99.14%) - -
2 Hrs 1.77 (98.315) 2.69 (99.79%) - -
Classmate Paperboard (Aqueous varnish + BKC) 15 mins 2.77 (99.83%) 3 (99.9%) - -
2 Hrs 3.17 (99.935) 4.10 (99.99%) - -

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from scope of the invention. It is intended that present invention covers such modifications and variations disclosed in the description.
,CLAIMS:1. An antimicrobial coating composition for a paper substrate comprising:
at least one organic antimicrobial agent;
at least one inorganic antimicrobial agent;
a solvent; and
optionally, at least one excipient/additive selected from the group that includes but not limited to a binding agent; a paper sizing agent and the like;
wherein the ratio of the amount of said organic anti-microbial agent to said inorganic antibacterial agent ranges from about 1:1 to about 1:6.

2. The coating composition as claimed in claim 1, wherein the amount of the organic anti-microbial agent ranges from about from 0.1 wt% to 0.3 wt% and the amount of the inorganic anti-microbial agent ranges from about 0.15-0.9 wt% of the coating composition.

3. An antiviral coating composition for a paper substrate comprising:
at least one organic antiviral agent;
at least one inorganic antiviral agent;
a solvent; and
optionally, at least one excipient/additive selected from the group that includes but is not limited to a binding agent; a paper sizing agent and the like;
wherein the ratio of the amount of said organic anti-viral agent to said inorganic antiviral agent ranges from about 1:1 to about 1:20.

4. The coating composition as claimed in claim 3, wherein the amount of the organic anti-viral agent ranges from about from 0.1 wt% to 0.75 wt% and the amount of the inorganic anti-viral agent ranges from about 0.15-2.0 wt% of the coating composition.

5. An antibacterial coating composition for a paper substrate comprising:
at least one organic antibacterial agent;
at least one inorganic antibacterial agent;
a solvent; and
optionally, at least one excipient/additive selected from the group that includes but is not limited to a binding agent; a paper sizing agent and the like;
wherein the ratio of the amount of said organic anti-bacterial agent to said inorganic antibacterial agent ranges from about 1:1 to about 1:6.

6. The coating composition as claimed in claim 5, wherein the amount of the organic anti-bacterial agent ranges from about from 0.1 wt% to 0.3 wt% and the amount of the inorganic anti-bacterial agent ranges from about 0.15-0.9 wt% of the coating composition.

7. The coating composition as claimed in claim 1 or 3 or 5, wherein the organic antimicrobial/ antibacterial/ antiviral agent is at least one quaternary ammonium compound selected from benzalkonium chloride, benzethonium chloride, methylbenzethonium chloride, cetalkonium chloride, cetylpyridinium chloride, cetrimonium, cetrimide, dofanium chloride, tetraethylammonium bromide, didecyldimethylammonium chloride and domiphen bromide.

8. The coating composition as claimed in claim 7, wherein the organic antimicrobial/ antiviral/ antibacterial agent is benzalkonium chloride.

9. The coating composition as claimed in claim 1 or 3 or 5, wherein the inorganic anti-microbial/ antiviral/ antibacterial agent is at least one selected from silver, zinc, copper, titanium and the like.

10. The coating composition as claimed in claim 9, wherein the inorganic anti-microbial/ antiviral/ antibacterial agent is titanium dioxide.

11. The coating composition as claimed in claim 1 or 3 or 5, wherein the solvent is selected from a non-aqueous solvent or an aqueous solvent depending upon the type of paper substrate to be coated.

12. The coating composition as claimed in claim 11, wherein the non-aqueous solvent is varnish and the aqueous solvent is water.

13. A paper substrate coated with an antimicrobial coating composition as claimed in claims 1-12, having
i. Cobb value below 35, preferably below 30 and most preferably below 25;
ii. GSM value between 30-90 GSM, preferably between 50 to 70 GSM; and
iii. log kill of at least 2, preferably above 2.5, and most preferably above 3.00 at 15 mins of exposure time after aging.

14. The paper substrate as claimed in claim 13, wherein said substrate is a paper with 50-70GSM.

15. The paper substrate as claimed in claim 13, wherein said substrate is selected from paper, cardboards/ paperboard items, packaging and packaging materials and the like.