DESC:AN ANTIMICROBIAL FORMULATION AND A TEXTILE PRODUCT COMPRISING THE SAME

TECHNICAL FIELD

[001] The present disclosure relates to an antimicrobial formulation and a textile product comprising the same and process of preparing thereof.
BACKGROUND

[002] Textiles functionalized with copper (CuO) nanoparticles have become a promising option to prevent the spread of disease due to their antimicrobial properties. In this regard, there exist several antimicrobial formulations comprising copper nanoparticles for applying on textile products. There is, however, only a narrow range of copper nanoparticles that has been described to be giving the desired effect. In addition to copper nanoparticles, these formulations also comprise various additives such as surfactants, binders, crosslinking agents, etc. known to the textile industry.

[003] The existing antimicrobial formulations are known to have several limitations owing to the presence of broad nanoparticle sizes and various additives, which may or may not result in the formulation being stable and therefore, resulting in a non-uniform distribution when applied on the textile products. Further, these formulations are also limited in terms of the characteristics imparted to the textile products coated with the same. For instance, most of the textile products are only known to have improved antimicrobial and deodorizing properties.

[004] Various methods for coating the textile product with the existing antimicrobial formulations have also been described. One commonly used method is ultrasonication which shows good binding properties resulting in the property lasting through several washes. Another known method is dip coating method. Application of copper nanoparticles on the textile product is another reported method wherein a binder may be used to bind the copper nanoparticle coating. However, the existing methods are complex and require very specific process conditions to obtain textile products having antimicrobial properties.
[005] Therefore, there is required an antimicrobial formulation which is stable and requires a simple method for coating on textile products, thereby resulting in a coated textile product having enhanced properties, such as but not limited to, antimicrobial, wash durability, wicking, and wrinkle free.

SUMMARY OF THE INVENTION
[006] In one aspect, the invention provides an aqueous antimicrobial formulation comprising:
(a) an aqueous surfactant suspension comprising 5 wt.% to 40 wt.% copper oxide (CuO) nanoparticles based on the total weight of the suspension, wherein the surfactant is a non-ionic surfactant or an anionic surfactant or a combination thereof,
(b) 0.1 wt.% to 10 wt.% of a binder based on the total weight of the antimicrobial formulation,
(c) 10 wt.% to 70 wt.% crosslinking agents based on the total weight of the antimicrobial formulation, and
(d) one or more additives.

[007] In another aspect, the invention provides a method for preparing an antimicrobial formulation comprising the steps of:
a. preparing a suspension comprising copper oxide (CuO) nanoparticles and an aqueous surfactant solution of one or more surfactants selected from non-ionic surfactants and anionic surfactants,
b. subjecting the suspension to ultra-sonication and/or fine grinding to obtain a uniform stable suspension,
c. diluting the suspension of step ‘b’ with water and mixing with a binder, a crosslinking agent and one or more additives selected from a lubricant, catalyst, softener, and dispersing agent to obtain an antimicrobial formulation.

[008] In yet another aspect, the invention provides a textile product comprising a fabric substrate which is coated with the antimicrobial formulation.

[009] In yet another aspect, the invention provides a process for preparing the textile product comprising the following steps:
a. applying antimicrobial formulation of the present invention to a fabric substrate through a trough containing the formulation,
b. evenly distributing the formulation applied in step ‘a’ via chemical padding the fabric substrate through a set of pneumatically operated padding mangle providing a specified add-on percentage of the formulation to the fabric substrate and providing a specified moisture to the fabric substrate through pick-up,
c. squeezing the fabric substrate obtained in step ‘b’,
d. drying the fabric substrate obtained from step ‘c’, and
e. high temperature cross linking or curing of the fabric substrate obtained from step ‘d’ to obtain a coated textile product.

DETAILED DESCRIPTION OF THE INVENTION
[010] The present invention is directed towards an antimicrobial formulation, the antimicrobial formulation comprises:
(a) an aqueous surfactant suspension comprising 5 wt.% to 40 wt.% copper oxide (CuO) nanoparticles based on the total weight of the suspension, wherein the surfactant is a non-ionic surfactant or an anionic surfactant or a combination thereof,
(b) 0.1 wt.% to 10 wt.% of a binder based on the total weight of the antimicrobial formulation,
(c) 10 wt.% to 70 wt.% crosslinking agents based on the total weight of the antimicrobial formulation, and
(d) one or more additives.

[011] In another embodiment, the weight ratio between the copper oxide (CuO) nanoparticles and the one or more surfactants in the suspension ranges between 1.0:10.0 to 10.0:1.0.

[012] In yet another embodiment, the amount of copper oxide (CuO) nanoparticles in the suspension preferably ranges in between 5 wt.% to 40 wt.%, based on the total weight of the suspension.
[013] In yet another embodiment, the copper oxide (CuO) nanoparticles have a particle size ranging between 10 nm to 300 nm.
[014] In an embodiment, the surfactants of the antimicrobial formulation are selected from non-ionic surfactants and anionic surfactants, preferably the non-ionic surfactants is selected from the group consisting of, but not limited to, ethoxylated amines, ethoxylated alcohol, alkyl and nonyl-phenol ethoxylates, ethoxylated sorbitan esters, and castor oil ethoxylate etc. and the anionic surfactant is selected from the group consisting of, but not limited to, alkyl ether sulfates, benzyl sulfonates, and phosphate esters, preferably, the anionic surfactants may be selected from sodium lauryl sulfate (SLS), sodium lauryl ether sulfate (SLES), ammonium lauryl sulfate (ALS), and ammonium lauryl ether sulfate (ALES).
[015] In an embodiment, the binder is an acrylic binder, preferably selected from an acrylic copolymer binder.
[016] In an embodiment, the acrylic binder of the antimicrobial formulation is used for fixation of pigments (Iron oxide, copper phthalocyanine etc.) on the textile product and is preferably an acrylic copolymer binder, wherein the acrylic copolymer binder is selected from the group consisting of, but not limited to, copolymer of acrylic acid ester and 2-chloroethyl vinyl ether and copolymer of acrylic acid ester and acrylonitrile.
[017] In an embodiment, the amount of acrylic binder in the antimicrobial formulation preferably ranges between 0.1 wt.% to 10 wt.% based on the total weight of the antimicrobial formulation.
[018] In an embodiment, the crosslinking agent is preferably selected from the group consisting of, but not limited to, N-Methylol dihydroxyethylene urea-based resins, N-Methylol dihydroxyethylene urea resins. The crosslinking agent provides for crosslinking of cellulose chain in the textile product and copper oxide as well as other components.

[019] In yet another embodiment, the amount of the crosslinking agent preferably ranges between 10 wt.% to 70 wt.% based on the total weight of the antimicrobial formulation.
[020] In an embodiment, the antimicrobial formulation comprises one or more additives preferably selected from lubricant, catalyst, softener, and dispersing agent or combination thereof.
[021] In an embodiment, the lubricant is preferably selected from the group consisting of, but not limited to, polyethylene, polyvinyl alcohol, High density polyethylene etc.
[022] In yet another embodiment, the amount of lubricant preferably ranges between 1 wt.% to 30 wt.% based on the total weight of the antimicrobial formulation.
[023] In an embodiment, the catalyst is preferably selected from the group consisting of, but not limited to, magnesium chloride, magnesium sulfate and magnesium nitrate.
[024] In yet another embodiment, the amount of catalyst in the formulation preferably ranges between 1 wt.% to 20 wt.% based on the total weight of the antimicrobial formulation.
[025] In an embodiment, the softeners are preferably selected from the group consisting of, but not limited to, macro silicone softener and micro silicone softener. Macro silicone softener is preferably a macro emulsion and provides for durable, hydrophilic silicone softening and smoothing of textile products of all fiber types and confer voluminous handle effects. Micro silicone softeners preferably include silicone quaternary polymer microemulsions and provide for hydrophilic silicone softening and smoothing of textile products of all fiber type, as well as stability over wide pH range.
[026] In yet another embodiment, the amount of macro silicone softeners and micro silicone softeners preferably ranges between 0.5 wt.% to 50 wt.% based on the total weight of the antimicrobial formulation.
[027] In an embodiment, the dispersing agent is preferably selected from the group consisting of, but not limited to, anionic and non-ionic surfactants. The dispersing agent ensures that the other additives remain dispersed in the formulation.
[028] In yet another embodiment, the amount of dispersing agent preferably ranges between 0.01 wt.% to 5 wt.% based on the total weight of the antimicrobial formulation.
[029] In an embodiment, the antimicrobial formulation of the present invention is an aqueous composition and comprises water as solvent.
[030] In yet another embodiment, the formulation comprises the copper oxide (CuO) nanoparticles in the form of a suspension in an aqueous surfactant solution wherein weight ratio between the copper oxide nanoparticles and the one or more surfactants in the suspension ranges between 1.0:10.0 to 10.0:1.0 and the copper oxide nanoparticles have a particle size ranging between 10 nm to 300 nm.
[031] In yet another embodiment, the copper oxide nanoparticles has the particle size ranging between 10 nm to 300 nm wherein the particle size of copper oxide described herein enables uniform dispersion, stable formulation, and wash durability to a textile product coated with the antimicrobial formulation. Moreover, the particle size range provides for better packing when coated on the textile product. The particle size of the nanoparticles can be characterized using conventional techniques, such as but not limited to, a Malvern analyzer.
[032] In another aspect, the present invention provides a method for preparing an antimicrobial formulation comprising the steps of:
a. preparing a suspension comprising copper oxide (CuO) nanoparticles and an aqueous surfactant solution of one or more surfactants selected from non-ionic surfactants and anionic surfactants,
b. subjecting the suspension to ultra-sonication and/or fine grinding to obtain a uniform stable suspension,
c. diluting the uniform stable suspension of step ‘b’ with solvent and mixing with an acrylic binder, a crosslinking agent and one or more additives selected from a lubricant, catalyst, softener, and dispersing agent to obtain the antimicrobial formulation.
[033] In an embodiment, the ultra-sonication and/or fine grinding for obtaining a uniform stable suspension is carried out for a duration ranging between 0.1 h to 1 h.
[034] In an embodiment, the dilution with solvent to obtain the antimicrobial formulation is accompanied with mixing at rpm ranging between 1000 rpm to 2500 rpm.
[035] In an embodiment, the solvent is preferably selected form water.
[036] In yet another aspect, the present invention provides a textile product comprising a fabric substrate which is coated with the antimicrobial formulation of the present invention.
[037] In an embodiment, the fabric substrate preferably selected from the group consisting of, but not limited to, sheeting, yarn dyed, solid dyed fabrics. It is more preferably selected from the group consisting of, but not limited to, natural cellulosic fibers, man-made cellulosic fibers, blends of natural and man-made cellulosic fibers (for e.g. nylon). In a preferred embodiment the fabric substrate is made of 100% Cotton or blended with other cellulosic fabrics. The weave structure of the fabric substrate can anyone known in the art like Sateen, Plain, Dobby, Twill etc.
[038] In yet another aspect, the present invention provides a process for preparing the textile product comprising the steps:
a. applying antimicrobial formulation as claimed in claims 1 to 11 to a fabric substrate through a trough containing the formulation,
b. evenly distributing the formulation applied in step ‘a’ via chemical padding the fabric substrate through a set of pneumatically operated padding mangle providing a specified add-on percentage of the formulation to the fabric substrate and providing a specified moisture to the fabric substrate through pick-up,
c. squeezing the fabric substrate obtained in step ‘b’,
d. drying the fabric substrate obtained from step ‘c’, and
e. high temperature cross linking or curing of the fabric substrate obtained from step ‘d’ to obtain a coated textile product.

[039] In an embodiment, the add on percentage during chemical padding of a fabric substrate is maintained in the range of 0.1% to 10 % and the pick-up percentage range is 30 % to 75% based on the weight of fabric substrate.

[040] In an embodiment, the fabric substrate is dried in the range of 80oC to 180oC, preferably between 105°C to 150°C to attain a moisture content of 0.5 % to 10 % based on the weight of fabric substrate.
[041] In an embodiment, the high temperature cross-linking or curing of the fabric substrate is done through a Stenter at a temperature range of 150°C to 180°C.
[042] The antimicrobial formulation is applied on the fabric substrate through padding technology using Stenter machine called “Stenter “, and the process steps comprises of chemical padding and squeezing then drying. The antimicrobial formulation of the present invention is applied through a trough containing the formulation, attached to a continuous replenishment mechanism. The applied formulation is evenly distributed on the material (fabric substrate) through a set of pneumatically operated padding mangle. The padding mangle helps to achieve the even distribution of formulation on the materials, maintaining proper add-on percentage of antimicrobial formulation and moisture through pick-up, the add-on percentage is maintained in the range of 0.1% to 10 % based on the weight of fabric substrate and the pick-up percentage range is 30 % to 75% based on the weight of fabric substrate.
[043] In the final section of the machine, the material is being dried to attain a moisture content of 0.5 % to 10 % based on the weight of fabric substrate. In the stenter machine the availability of drying chambers is from 1 to 12, depending on the moisture regain on the final material which varies from 0.5% to 10 % and speed of production, the number of chambers used in the stenter can be decided.
[044] The application on continuous fabric wet processing machine using Stenter is followed by a second passage of curing, i.e. high temperature cross-linking. It is a fixing stage and aids in binding copper oxide nanoparticles into cellulosic structure of the substrate so that during multiple washes, the nanoparticles remain stationed inside the fiber.
[045] In one embodiment, the textile product may be used in, such as but not limited to, bed linens, home furnishing and upholstery items, bottom weights, shirting, formal, casual and the likes, having very good anti-microbial and wellness properties.

[046] The antimicrobial formulation, as described herein, imparts the following advantages to the textile product:
- Wrinkle free or crush-less textile product (depicted by AATCC 124-2014),
- Anti-bacterial property up to 50 washes (depicted by AATCC 100-2019),
- Post wash softness and odor free for 50 washes,
- Enhanced moisture management (depicted by AATCC 124-2014)

EXAMPLE

[047] The following example is illustrative of the invention but not limitative of the scope thereof:
[048] Preparation of suspension:
Step 1: To 100 gm of Sodium Lauryl Ether Sulphate (SLES), 800 ml water was slowly added to get 10% SLES, 900g solution.
Step 2: 100 gm of copper oxide nano particles was added to Step 1, i.e. to 900g 10% SLES solution followed by mixing the solution properly to get a suspension of 10% copper oxide with 10% SLES.
Step 3: The 10% copper oxide suspension was subjected to ultra-sonication or fine grinding for 30-45 min to get thoroughly uniform stable suspension.
Step 4: 1050 ml of concentrated suspension from step 3 was taken and small amounts of water was added gradually and continued with stirring for 45 minutes at 1900 rpm. A 2000 ml of solution was prepared.

[049] Preparation of fabric coated with antimicrobial formulation
[050] Example 1: 100 gram of Sodium Lauryl Ether Sulphate (SLES) was added to 800 ml water to dissolve it and get 10% SLES solution. 100 gram of copper oxide nanoparticle was added to the 10% SLES solution. The solution was mixed to get a suspension of 10% CuO with 10% SLES. The 10% CuO suspension was subjected to ultra-sonication or fine grinding for 30-45 min to get thoroughly uniform stable suspension. The suspension was further diluted to 500 ppm and mixed in a stirred vessel with 0.5% acrylic polymer binder and 1% dimethylol dihydroxy ethylene urea (DMDHEU) resin. The prepared formulation was then applied on a textile fabric (100% cotton) using padding coating machine. The coated fabric was then cured at 170°C to obtain a textile product.

[051] Example 2: 50 gram of Sodium Lauryl Ether Sulphate (SLES) was added to 850 ml water to obtain 5% SLES solution. 100 gram of CuO nano powder was added to the 5% SLES solution. The solution was properly mixed to get a suspension of 10% CuO with 5% SLES. The 10% CuO suspension was then subjected to ultra-sonication or fine grinding for 30-45 min to get thoroughly uniform stable suspension. The suspension was further diluted to 1000 ppm and mixed in a stirred vessel with 0.1% acrylic polymer binder and 1% dimethylol dihydroxy ethylene urea (DMDHEU) resin, 0.2% magnesium chloride, 0.3% polyethylene, and 0.5% silicone softener. The prepared formulation was then applied on a textile cotton fabric (100% cotton) using padding coating machine. The coated fabric was then cured at 170°C to obtain a nano CuO coated fabric with wrinkle-free and softening properties

[052] Example 3: 50 gram of Sodium Lauryl Ether Sulphate (SLES) was added to 850 ml water to obtain 5% SLES solution. 100 grams of CuO nano powder was added to the 5% SLES solution. The solution was properly mixed to get a suspension of 10% CuO with 5% SLES. The 10% CuO suspension was then subjected to ultra-sonication or fine grinding for 30-45 min to get thoroughly uniform stable suspension. The suspension was further diluted to 2000 ppm and mixed in a stirred vessel with 0.1% acrylic polymer binder and 1% dimethylol dihydroxy ethylene urea (DMDHEU) resin, 0.2% magnesium chloride, 0.3% polyethylene, and 0.5% silicone softener. The prepared formulation was then applied on a textile fabric (100% cotton) using padding coating machine. The coated fabric was then cured at 170°C to obtain a nano CuO coated fabric with wrinkle-free and softening properties.

[053] Example 4: 70 gram of Sodium Lauryl Ether Sulphate (SLES) was added to 830 ml water to obtain 7% SLES solution. 100 grams of CuO nano powder was added to the 7% SLES solution. The solution was properly mixed to get a suspension of 10% CuO with 7% SLES. The 10% CuO suspension was then subjected to ultra-sonication or fine grinding for 30-45 min to get thoroughly uniform stable suspension. The suspension was further diluted to 2000 ppm and mixed in a stirred vessel with 0.1% acrylic polymer binder and 1% dimethylol dihydroxy ethylene urea (DMDHEU) resin, 0.2% magnesium chloride, 0.3% polyethylene, and 0.5% silicone softener. The prepared formulation was then applied on a textile fabric (100% cotton) using padding coating machine. The coated fabric was then cured at 170°C to obtain a nano CuO coated fabric with wrinkle-free and softening properties.

[054] Example 5: 50 gram of Sodium Lauryl Ether Sulphate (SLES) was added to 850 ml water to obtain 5% SLES solution. 100 grams of CuO nano powder was added to the 5% SLES solution. The solution was properly mixed to get a suspension of 10% CuO with 4% SLES. The 10% CuO suspension was then subjected to ultra-sonication or fine grinding for 30-45 min to get thoroughly uniform stable suspension. The suspension was further diluted to 500 ppm and mixed in a stirred vessel with 0.1% acrylic polymer binder and 1% dimethylol dihydroxy ethylene urea (DMDHEU) resin, 0.2% magnesium chloride, 0.3% polyethylene, and 0.5% silicone softener. The prepared formulation was then applied on a textile fabric (100% cotton) using padding coating machine. The coated fabric was then cured at 170°C to obtain a nano CuO coated fabric with wrinkle-free and softening properties.

[055] The coated fabric was evaluated for wrinkles, post-wash softness, odor, enhanced moisture management, anti-bacterial and anti-viral property as follows:

[056] Test 1: DP (Durable Press) assessment (Wrinkle Free) was tested as per AATCC 124-2014 for all the examples and demonstrated DP >3, which implies wrinkle free or crush less surface present on the textile product even after multiple washes.

[057] Test 2: Wicking height measurement was done as per AATCC 197-2013 and confirms moisture management for comfortable use whether apparel or bed linens. Wicking height > 10 cm achieved in 30 minutes showing very good effects of moisture management in the textile product. Table 1 below summarizes wicking height results for woven cotton fabric.

Table 1: Wicking height results for woven cotton fabric of Example 1
Sample Wicking height achieved Time
Woven Cotton Fabric Length- 15cm 27 mins 48 secs
Width -14.6cm 30 mins

[058] The test results of further Examples 2 to 5 also fall in the range of 14.5 to15.5 cm length wise and 14.1 to 15.2 cm width wise under observation for 30 mins which is supposed to be very effective against target of >10 cm in 30 minutes. It adds value to quick drying behavior of finished fabrics.

[059] Feel of freshness wellness due to killing of microbes which create foul smell or odor with sweat can be felt during the use of textile products coated with the antimicrobial formulation, as described herein, vs the non-coated textile products.

[060] Test 3: Anti-microbial effectiveness as per AATCC 100-2019 was measured for fabric sample swatches (Example 4) in contact with individual test culture after multiple washes. The inoculum used in the method was as follows:
1. Staphylococcus aureus ATCC 6538 (1 .90 x 105 CFU/mg)
2. Klebsiella pneumoniae ATCC 4352 (2.00 x 105 CFU/ml)

Further, additional test information is as follows:
Sample size : 48 mm discs (Lot no; 878503 – Grey color)
Pre-treatment of sample : Non-sterile
No. of swatches used : 1.0 g ± 0.1 g
lnoculum Carrier : Phosphate Buffered saline
Neutralizer : DE Broth

[061] The 100% cotton fabric sample treated with antimicrobial formulation (Example 4) was kept in contact with individual test cultures for 24 hrs at 37oC showed the following results of Table 2:

Table 2: Anti-microbial effectiveness result of Example 4
S. No. Test Organism Number of Washes Percentage
Reduction in Bacteria
1. Staph. aureus 20 99.02
K. pneumoniae 20 98.96
MS2 Bacteriophage 20 >99.98
2. Staph. aureus 30 98.78
K. pneumoniae 30 98.64
MS2 Bacteriophage 30 >99.98
3. Staph. aureus 40 98.35
K. pneumoniae 40 97.92
MS2 Bacteriophage 40 >99.98
4. Staph. aureus 50 98.23
K. pneumoniae 50 97.75
MS2 Bacteriophage 50 >99.98

[062] It can be seen that the 100% cotton fabric sample after 50 washes has shown 98.23% and 97.75% antimicrobial activity towards Staphylococcus aureus and Klebsiella pneumoniae respectively when analyzed as per AATCC 100 - 2019 test Method.

[063] Test-4: A 100% cotton fabric sample treated with antimicrobial formulation (Example 4) was evaluated for antimicrobial activity by AATCC 100-2019 test method. The inoculum used in the method was as follows:
1. Staphylococcus aureus ATCC 6538 (1 .70 x 105 CFU/mg)
2. Klebsiella pneumoniae ATCC 4352 (1.80 x 105 CFU/ml)

Further, additional test information is as follows:
Sample size : 48 mm discs (Lot No.: 896421, Shade-Brown)
Pre-treatment of sample : ETO Sterilisation
No. of swatches used : 1.0 g ± 0.1 g
lnoculum Carrier : 1:500 Nutrient Broth + 0.05% Triton X-100
Neutralizer : DE Broth

[064] The 100% cotton fabric sample treated with antimicrobial formulation (Example 4) was kept in contact with individual test cultures for 24 hrs at 37oC showed the following results of Table 3:
Table 3: Anti-microbial effectiveness result of Example 4
Sample
identification Test
Organism No. of Bacteria per sample (CFU/ Sample) Percentage
Reduction of
Bacteria (R)
lnoculated Treated
Sample
at 0 hrs. (C) lnoculated Treated
Sample
at 24 hrs.(A)
Count: 70/1 NE
COMPACT X 10/1 NE
NORMAL; Shade- Brown
After 50 washes Staph. aureus 1.76 x 105 2.70 x 103 98.46
K. pneumoniae 1.87 x 105 6.10 x 103 96.73
CFU: Colony Forming Unit = No. of Microorganisms
Percentage Reduction of Microorganisms (R) = 100 (C – A/C)

[065] It can be seen that the 100% cotton fabric sample labeled as Count: 70/1 NE COMPACT X 10/1 NE NORMAL; Shade- Brown - After 50 washes has shown 98.46% and 96.73% antimicrobial activity towards Staphylococcus aureus and Klebsiella pneumoniae respectively when analyzed as per AATCC 100 - 2019 test Method.

[066] Test-5: A fabric specimen labeled as ‘Unfinished Fabric’ which is not treated with the antimicrobial formulation of the present invention and a ‘Finished Fabric’ treated with antimicrobial formulation (Example 4) was evaluated for antimicrobial activity by AATCC 100-2019 test method. The inoculum used in the method was as follows:
1. Staphylococcus aureus ATCC 6538 (1.80 x 105 CFU/ml)
2. Klebsiella pneumoniae ATCC 4352 (1.90 x 105 CFU/ml)

Further, additional test information is as follows:
Sample size : 48 mm discs (Lot No.: 896421)
Pre-treatment of sample : ETO Sterilisation
No. of swatches used : 1.0 g ± 0.1 g
Inoculum Carrier : 1:500 Nutrient Broth + 0.05% Triton X-100
Neutralizer : DE Broth

[067] The fabric specimen labeled as ‘Unfinished Fabric’ and a ‘Finished Fabric’ kept in contact with individual test cultures for 24 hrs at 37oC showed the following results of Table 4:

Table 4: Anti-microbial effectiveness result of Example 4
Sample
Identification Test
Culture No. of Bacteria per sample (CFU/Sample) Percentage
Reduction of
Microorganism
(R)
Inoculated Sample
at 0 hours (C) Inoculated Sample
at 24 hours (A)
Unfinished Fabric Staph. aureus 1.82 x 105 7.40 x 104 59.34
K. pneumoniae 1.92 x 105 1.72 x 105 10.41
Finished Fabric Staph. aureus 1.84 x 105 <10 >99.99
K. pneumoniae 1.96 x 105 <10 >99.99
CFU: Colony Forming Unit = No. of Microorganisms
Percentage Reduction of Microorganisms (R) = 100 (C- A/ C)

[068] It can be seen that the fabric labelled as ‘Unfinished Fabric’ has shown 59.34% and 10.41% antimicrobial activity. In contrast, the fabric labelled as ‘Finished Fabric’ has shown >99.99% and >99.99% antimicrobial activity towards Staphylococcus aureus and Klebsiella pneumoniae respectively when analyzed as per AATCC 100 - 2019 test Method.

[069] Test-6: A 100% Cotton fabric sample treated with antimicrobial formulation (Example 4) was evaluated for antiviral activity of fabric by modified AATCC 100-2012 test method. MS2 Bacteriophage (MS2) is an RNA virus of the family Leviviridae. Escherichia coli 15597 are the hosts for MS2 bacteriophages. Due to its environmental resistance, MS2 bacteriophages are used as a surrogate virus (particularly in place of Picornaviruses such as Poliovirus and human Norovirus) in water quality and antimicrobial studies. Accordingly, the test microorganism used in the study is as follows:
Virus: MS2 Bacteriophage
Permissive Host Cell: Escherichia coli ATCC 15597

Further, additional parameters used in study is as follows:
Sample size :48 mm discs (Lot No.: 896421, Shade-Brown)
No. of swatches used : 0.75 gram
Method of Sterilization of sample : Autoclaving
Viral lnoculum Volume : 0.5 ml; 1.10 x 106 PFU/ ml
Host Cell Line : E. coli15597
Dilution Medium : Phosphate Buffered Saline (PBS)
Contact Time : 2 hours and 24 hours at 35oC
TSA Neutralizer : 10 ml D/E broth
Assay Medium : 50% TSA agar
lncubation Period : 48 hours

[070] The procedure adopted in the study for evaluating the antiviral activity of the fabric is as follows:
1. Test and control Fabrics are cut into appropriately sized swatches of 50 mm diameter and stacked. The numbers of swatches taken are enough to absorb the entire liquid inoculum of 0.5 ml quantity.
2. Stock virus is standardized to prepare a test inoculum.
3. Test and control materials are inoculated with the test virus and incubated in a humid environment at 35oC temperature for 2 hours and 24 hours contact time.
4. The viral concentration is determined at “Time Zero” to verify the target inoculums using plaque assay techniques. Assay plates are incubated for 48 hours for the virus-host cell system.
5. After the incubation period, following neutralization, the carrier suspensions are quantified to determine the levels of infectious virus survived and the assay is scored for titre of test virus.
6. Adequate control is implemented to verify neutralization effectiveness of the antimicrobial agent with Neutralizer used.
7. Percent reductions are computed for test Fabric relative to the Time Zero enumeration(s), and reported.

[071] The 100% Cotton fabric sample treated with antimicrobial formulation in contact with test organism for 2 hours & 24 hours at 35oC showed the following results of Table 5:

Table 5: Anti-microbial effectiveness result of Example 4
Sample
identification Test Organism:
MS2 Bacteriophage Log
Reduction
of Virus
at
2 hours Percentage
Reduction
of Virus
at
2 hours MS2
Bacteriophage Log
Reduction
of Virus
at
24 hours Percentage
Reduction
of Virus
at
24 hours
Average
PFU/Carrier
at
0 hours (B) Average
PFU/Carrier
at
2 hours (A) Average
PFU/Carrier
at 2 hours (A)
PFU log PFU log PFU log
Count:70/1 NE
COMPACTX
10/1 NE
NORMAL;
Shade- Brown
After 50
washes 9.10
x104 4.95 3.20
x 102 2.50 2.45 99.64 <10 <1 >3.95 >99.98
Lab Control -
Untreated 1.20 x105 5.07 0.00 0.00 1.40 x105 5.14 0.00 0.00
PFU: Plaque Forming Unit = No. of Microorganisms
Percentage Reduction = (B – A/B) x 100
Log reduction Log (B/A)
Where:
B = Number of viable test microorganisms on the control carriers immediately after inoculation
A = Number of viable test microorganisms on the test carriers after the contact time

[072] It can be seen that the 100% cotton fabric sample labeled as Count: 70/1 NE COMPACT X 10/1 NE NORMAL; Shade- Brown - After 50 washes has shown 99.64% and >99.98% reduction of virus in 2 hours and 24 hours respectively when analyzed as per AATCC 100 -2012 test Method using MS2 Bacteriophage as surrogate virus.

[073] The foregoing description of the invention has been set merely to illustrate the invention and is not intended to be limiting. Since the modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to the person skilled in the art, the invention should be construed to include everything within the scope of the disclosure.

,CLAIMS:We Claim:
1. An aqueous antimicrobial formulation comprising:
(a) an aqueous surfactant suspension comprising 5 wt.% to 40 wt.% copper oxide (CuO) nanoparticles based on the total weight of the suspension, wherein the surfactant is a non-ionic surfactant or an anionic surfactant or a combination thereof,
(b) 0.1 wt.% to 10 wt.% of a binder based on the total weight of the antimicrobial formulation,
(c) 10 wt.% to 70 wt.% crosslinking agents based on the total weight of the antimicrobial formulation, and
(d) one or more additives.

2. The formulation as claimed in claim 1, wherein the weight ratio between the copper oxide (CuO) nanoparticles and the surfactant in the suspension ranges between 1.0:10.0 to 10.0:1.0.

3. The formulation as claimed in claim 1 to 2, wherein the copper oxide (CuO) nanoparticles have a particle size ranging between 10 nm to 300 nm.

4. The formulation as claimed in claim 1, wherein the non-ionic surfactant is selected from ethoxylated amines, ethoxylated alcohol, alkyl and nonyl-phenol ethoxylates, ethoxylated sorbitan esters, and castor oil ethoxylate and the anionic surfactant is selected from alkyl ether sulfates, benzyl sulfonates, and phosphate esters, preferably, the anionic surfactants may be selected from sodium lauryl sulfate (SLS), sodium lauryl ether sulfate (SLES), ammonium lauryl sulfate (ALS), and ammonium lauryl ether sulfate (ALES).

5. The formulation as claimed in claim 1, wherein the binder is an acrylic binder, preferably selected from an acrylic copolymer binder.

6. The formulation as claimed in claim 1, wherein the crosslinking agent is selected form N-Methylol dihydroxyethylene urea-based resins.

7. The formulation as claimed in claim 1, wherein one or more additives is selected from lubricant, catalyst, softener, and dispersing agent.

8. The formulation as claimed in claim 7, wherein the lubricant is polyethylene in an amount ranging between 1 wt.% to 30 wt.% based on the total weight of the antimicrobial formulation.

9. The formulation as claimed in claim 7, wherein the catalyst is selected from magnesium chloride, magnesium sulfate and magnesium nitrate in an amount ranging between 1 wt.% to 20 wt.% based on the total weight of the antimicrobial formulation.

10. The formulation as claimed in claim 7, wherein the softener is selected from macro silicone softener and micro silicone softener in an amount ranging between 0.5 wt.% to 50 wt.% based on the total weight of the antimicrobial formulation.

11. The formulation as claimed in claim 7, wherein the amount of dispersing agent ranges between 0.01 wt.% to 5 wt.% based on the total weight of the antimicrobial formulation.

12. A method for preparing an antimicrobial formulation comprising the steps of:
a. preparing a suspension comprising copper oxide (CuO) nanoparticles and an aqueous surfactant solution of one or more surfactants selected from non-ionic surfactants and anionic surfactants,
b. subjecting the suspension to ultra-sonication and/or fine grinding to obtain a uniform stable suspension,
c. diluting the suspension of step ‘b’ with water and mixing with a binder, a crosslinking agent and one or more additives selected from a lubricant, catalyst, softener, and dispersing agent to obtain an antimicrobial formulation.

13. The method as claimed in claim 12, wherein the ultra-sonication and/or fine grinding is carried out for a duration ranging between 0.1 h to 1 h.

14. The method as claimed in claim 12, wherein the dilution with water is accompanied with mixing at rpm ranging between 1000 rpm to 2500 rpm.

15. A textile product comprising a fabric substrate which is coated with the antimicrobial formulation as claimed in claims 1 to 11.

16. The textile product as claimed in claim 15, wherein the fabric substrate is selected from sheeting, yarn dyed, solid dyed fabrics, preferably selected from natural cellulosic fibers, man-made cellulosic fibers, blends of natural and man-made cellulosic fibers.

17. A process for preparing a textile product as claimed in claims 15 to 16 comprising the steps:
a. applying antimicrobial formulation as claimed in claims 1 to 11 to a fabric substrate through a trough containing the formulation,
b. evenly distributing the formulation applied in step ‘a’ via chemical padding the fabric substrate through a set of pneumatically operated padding mangle providing a specified add-on percentage of the formulation to the fabric substrate and providing a specified moisture to the fabric substrate through pick-up,
c. squeezing the fabric substrate obtained in step ‘b’,
d. drying the fabric substrate obtained from step ‘c’, and
e. high temperature cross linking or curing of the fabric substrate obtained from step ‘d’ to obtain a coated textile product.

18. The process as claimed in claim 18, wherein the add on percentage is in the range of 0.1% to 10 % and the pick-up percentage range is 30 % to 75% based on the weight of fabric substrate.

19. The process as claimed in claim 18, wherein the substrate is dried to attain a moisture content of 0.5 % to 10 % based on the weight of fabric substrate.

20. The process as claimed in claim 18, wherein the high temperature curing is done at a temperature range of 150°C to 180°C.