An antimicrobial polymer coating

Technical Field
Present disclosure relates in general to a field of Surface Engineering. Particularly, but not exclusively, the present disclosure relates to an antimicrobial polymer coating.
Background of the Disclosure
The health hazard coming from bacteria and viruses were noticed during COVID -19 pandemic situation worldwide. People are now conscious on contacting common facilities for virus and bacteria spread and spread of infections.
Conventionally coating has one main purpose of protecting the surface from rust and corrosion. As development progress, the aesthetic or appearance become another key parameter for coating. Broadly, coating has two divisions liquid paint and powder coating. The powder coating has indoor and outdoor uses in both commercial and residential level. The common applications of powder coatings are on doors, grills, furniture (metal/ non-metals), airports, appliances, white goods, railways, automobile etc. These powder coating applications are for longer durability. During routine life people touches the surface of these material many times in a day. Therefore, it is long lasting need in the industry to develop coating which can resist the growth of bacteria, viruses and fungi over coated substrate. Bacteria, viruses and fungi spread infection, microbial corrosion etc.
Various antimicrobial ingredient have been tried. Although various coatings include the antimicrobial additive, but they are toxic and hazardous for e.g. Biocide, pesticide, inorganic nano-material of copper etc. Some of the antimicrobial additives are difficult to embed in polymer powder, thereby imparts negative impact on corrosion, curing, application, aesthetic and mechanical properties.
WO 2016/187618 Al patent reveals the use of inorganic bismuth containing compound a bismuth salt of a metal oxyanion more specifically bismuth aluminate in powder coating formulation to make it microbe resistant. But it may suffer with product appearance and long term performance.
Objects
An object of the invention is to design an antimicrobial polymer coating for a substrate.
Another object of the invention is to design the antimicrobial polymer coating which is safe and non-hazardous for environment and health.
Another object of the invention is to design economical antimicrobial polymer coating.
Disclosure of the Invention
The invention provides an antimicrobial polymer powder coating over a substrate comprising:
a coating mix;
an antimicrobial agent,
the antimicrobial agent being combination of para chloro meta xylenol (PCMX) and/or an amorphous silver, and
the antimicrobial agent being 0.01-3 wt% of the antimicrobial polymer powder coating for providing antimicrobial property.
PCMX is the phenol-based compound which possess antimicrobial property. The PCMX in the coating also doesn’t impact the physical and chemical properties of the coating. It makes the bond with the coating and becomes the integral part therefore it, therefore does not leach and give the antimicrobial performance for the longer duration. The PCMX is positively charged molecule and the bacterial cell wall contains negative charge on it. When the bacterial cell wall comes in contact with PCMX, electrostatic interaction is established, which further ruptures the bacterial cell wall and cytoplasm gets exposed, which subsequently leads to killing of bacteria. The amorphous silver is so chosen as it is stable upto 700 deg. C and inert. Therefor it is not leachable. Hence it also provides longevity.
The coating mix can be powder coating or coil coating.
The coating mix in an embodiment comprises a resin with 60-70 wt.% for powder coating or 15-40 wt% for coil coating for providing corrosion resistivity; a hardener with 5-11 wt.% for powder coating or 10-25 wt.% for coil coating for crosslinking to the resin; a filler with 4-8 wt.% for powder coating or 5-10 wt.% for coil coating for providing abrasion resistance and porosity reduction; a pigments with 12-22 wt.% for powder coating or 5-22 wt.% for coil coating for colouring, hammer-tone, metallic structured finish; an additive with 1-3 wt.% for flow control; and optionally a solvent 40-60 wt.% for coil coating for coating transfer over the substrate.
The resin can be one or in combination(s) of Silicon modified polyester (SMP), Regular modified polyester (RMP), polyvinylidene fluoride (PVDF), Polyvinylchloride (PVC), Polyurethane (PU), Epoxy, Polyester, Polyurethane, Polyninyl chloride, Epoxy chemistry, thermoset polymer of TGIC (triglycidyl isocyanurate) / Non-TGIC polyester or polyester.
The hardener can be one or in combination(s) of Polyisocyanates, Anhidrides, amines and polyphenols.
The filler can be one or in combination(s) of Barium sulfate, Mica, Calcium carbonate (calcite), Calcium manganese carbonate (dolomite), Wollastonite, Kaolin.
The pigment can be one or in combination(s) of titanium dioxide, red oxide, yellow oxide, carbon black, aluminium flakes.
The additive can be one or in combination(s) of acrylics and silica.
The solvent can be one or in combination(s) of Xylene, Toulene, isopropyl alcohol, Acetonitrile, Benzene, dibasic ester.
The substrate can be steel or galvanised steel or aluminium or wood or plastic or Galvalume or Galfan, or Magizinc or Al-Si coated steel.
In an embodiment size of amorphous silver-based glass material is 10 nm to 40 microns.
In another embodiment the invention provides an antimicrobial substrate comprising:
a substrate (304); and
an antimicrobial polymer coating (308) over the substrate, the antimicrobial polymer coating comprising
a coating mix and an antimicrobial agent,
the antimicrobial agent being a combination of para chloro meta xylenol (PCMX) and/or an amorphous silver, and
the antimicrobial agent being 0.01-3 wt% of the antimicrobial polymer coating for providing antimicrobial property.
The size of the antimicrobial agent can be 0.01 to 0.5 times the thickness of the antimicrobial polymer coating.
The substrate can be steel or galvanised steel or aluminium or wood or plastic or Galvalume or Galfan, or Magizinc or Al-Si coated steel.
In another embodiment the invention provides a method of making an antimicrobial substrate, the method comprising:
preparing a coating mix in a homogenizing chamber;
adding an antimicrobial agent to the coating mix in the homogenizing chamber;
the antimicrobial agent being combination of para chloro meta xylenol (PCMX) and/or an amorphous silver, the antimicrobial agent being 0.01-3 wt% of the antimicrobial polymer coating for providing antimicrobial property’
layering the antimicrobial polymer coating over a substrate, by a layering unit; and
curing the antimicrobial polymer coating at 150 Deg C to 300 Deg C.
The curing can be done for 2-15 minutes
The substrate can be steel or galvanised steel or aluminium or wood or plastic or Galvalume or Galfan or Magizinc or Al-Si coated steel.
The layering unit can be electrostatic spray gun or roll coater.
In an embodiment the coating mix comprises of
a resin with 60-70 wt.% for powder coating or 15-40 wt.% for coil coating for providing corrosion resistivity;
a hardener with 5-11 wt.% for powder coating or 10-25 wt.% for coil coating for crosslinking to the resin;
a filler with 4-8 wt.% for powder coating or 5-10 wt.% for coil coating for providing abrasion resistance and porosity reduction;
a pigments with 12-22 wt.% for powder coating or 5-22 wt.% coil coating for colouring, hammer-tone, metallic structured finish; and
an additive with 1-3 wt.% for flow control; and
optionally a solvent 40-60 wt.% for coil coating for coating transfer over the substrate.
The curing can be done by heating.

Brief description of the accompanying drawings
The novel features and characteristics of the disclosure are set forth in the appended description. The disclosure itself, however, as well as a preferred mode of use, further objectives, and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying figures. One or more embodiments are now described, by way of example only, with reference to the accompanying figures wherein like reference numerals represent like elements and in which:
FIG. 1 illustrates a structure of PCMX (para-chloro-meta-xylenol).
FIG. 2 illustrates a structure of amorphous silver.
FIG. 3 illustrates an antimicrobial substrate in accordance with an embodiment of the invention.
FIG. 4 illustrates a process for making an antimicrobial substrate in accordance with an embodiment of the invention.
Detailed description of a preferred embodiment
In accordance with an embodiment of the invention an antimicrobial polymer coating (hereinafter referred as “coating”) over a substrate is disclosed.
The coating comprises of a coating mix and an antimicrobial agent, the antimicrobial agent being combination of para-chloro-meta-xylenol (PCMX) and/or an amorphous silver. The antimicrobial agent being 0.01-3 wt% of the antimicrobial polymer coating for providing antimicrobial property.
The PCMX provides better bonding with the substrate.
The structure of the PCMX is shown in FIG. 1. The PCMX is the phenol-based compound which possess antimicrobial property. PCMX makes the bond with the coating and becomes the integral part therefore it, therefore does not leach and give the antimicrobial performance for the longer duration. The flash point of the PCMX is 120-140 deg. C.
The PCMX is positively charged molecule and the bacterial cell wall contains negative charge on it. When the bacterial cell wall comes in contact with PCMX, electrostatic interaction is established, which further ruptures the bacterial cell wall and cytoplasm gets exposed, which subsequently leads to killing of bacteria.
The structure of the amorphous silver is provided in FIG. 2. The amorphous silver is so chosen as it is stable upto 700 deg. C and inert. Therefor it is not leachable. Hence it also provides longevity. Silver embedded in glass form can be witnessed. In an embodiment the shape of the amorphous silver is shown to be round, whereas in reality it may have other shapes.
The size of amorphous silver-based glass material varies from 10 nm to 40 microns. It can be witnessed from Fig. 2 that silver nanoparticles are embedded within the matrix. These embedded nanoparticles are strongly bonded with each other; hence they do not leach out so easily and remains in the matrix for long time.
In accordance with an embodiment of the invention, the PCMX and the amorphous silver are both added in the form of powder. The sizes of the PCMX and the amorphous silver depends on the thickness of the coating to be applied.
If size of the of the antimicrobial agent is more or comparable with the thickness of the coating, the particles may get appear when coating is done on the substrate, which may not give appropriate coating properties. Also, the spots may get appear over the coat. Therefore, size of the antimicrobial agent used in an embodiment lies in the range of 0.01 to 0.5 times the thickness of coating applied.
The antimicrobial agent may be in liquid, solid, or semisolid state.
In an embodiment of the invention, PCMX is added in the coating mix with no amorphous silver with 0.01-3 wt% of the antimicrobial polymer powder coating. In another embodiment amorphous silver is added alone in the coating mix with no PCMX and 0.01-3 wt% of the antimicrobial polymer powder coating. In yet another embodiment, the PCMX and the amorphous silver are added in combination with 0.01-3 wt% of the antimicrobial polymer powder coating.
Post adding the antimicrobial agent in the coating mix, it is stirred so that the (PCMX) and/or the amorphous silver gets homogenised.
In an embodiment, the antimicrobial agent is added during or after the formation of the coating mix.
In an embodiment, coating mix can be powder coating or coil coating.
In an embodiment, the coating mix comprises the following:
A resin (60-70 wt%) is being used for powder coating and 15-40 wt.% for coil coating. The resin is used for providing corrosion resistivity. In accordance with an embodiment of the invention, the resin used can be one or in combination(s) of Silicon modified polyester (SMP), Regular modified polyester (RMP), polyvinylidene fluoride (PVDF), Polyvinylchloride (PVC), Polyurethane (PU), Epoxy, Polyester, Polyurethane, Polyninyl chloride, Epoxy chemistry, thermoset polymer of TGIC (triglycidyl isocyanurate) / Non-TGIC polyester or polyester.
A hardener (5-11 wt%) is being used for powder coating and 10-25 wt.% for coil coating. The hardener is used for crosslinking to the resin. In accordance with an embodiment of the invention the hardner used is one or in combination(s) of Polyisocyanates, Anhidrides, amines and polyphenols.
A filler (4-8 wt%) is used for powder coating and 5-10 wt.% for coil coating. The filler is used for providing abrasion resistance and porosity reduction. In accordance with an embodiment of the invention the filler used is one or in combination(s) of Barium sulfate, Mica, Calcium carbonate (calcite), Calcium manganese carbonate (dolomite), Wollastonite, Kaolin.
A pigment (12-22 wt%) is used for powder coating and 5-22 wt.% for coil coating. The pigment is used for colouring, providing hammer-toning, and metallic structured finish. In accordance with an embodiment of the invention the pigment used are one or in combination(s) of titanium dioxide, red oxide, yellow oxide, carbon black, aluminium flakes.
An additive (1-3 wt%) is used for powder coating and for coil coating. The additive is used for flow control of the coating. In accordance with an embodiment of the invention the additive used are is one or in combination(s) of acrylics and silica.
A solvent 40-60 wt.% is being used only for coil coating. The solvent is configured to transfer coating over the substrate. During curing of the coating, the solvent evaporates leaving behind the rest.
In accordance with an embodiment of the invention, the solvent can be one or in combination(s) of Xylene, Toulene, isopropyl alcohol, Acetonitrile, Benzene, dibasic ester.
It is to be appreciated that amount of antimicrobial agent to be added in the coating mix is to achieve the antimicrobial properties with longevity. The amount of antimicrobial agent beyond 0.01 to 3 wt %, may affect the properties such as adhesion, bending property, peel-off property etc.
The substrate in an embodiment can be steel or galvanised steel or aluminium or wood or plastic or Galvalume or Galfan, or Magizinc or Al-Si coated steel.
Shown in FIG. 3 is an antimicrobial substrate (300) in an embodiment comprising the substrate (304), and the antimicrobial polymer coating (308) over the substrate.
The powder coating over the substrate in an embodiment is done by means of spraying through electrostatic gun which charge the powders and spray on substrate. The substrate needs to be grounded. The charged polymer powder particles of the powder coating are sprayed onto the substrate until a desired thickness is achieved. Other powder coating techniques like fluidize- bed or thermal or flame spraying may also be used.
The coil coating over the substrate in an embodiment is done by means of roll coater.
Shown in FIG. 4 is a method (400) for making the antimicrobial substrate using coating. The method (400) comprises steps of
preparing the coating mix in a homogenising chamber-Step (404). Post that the antimicrobial agent is added to the coating mix and stirred at step 408. The addition of the antimicrobial agent is also done in the homogenising chamber.
The coating mix is extruded in an polymer extruder.
Coating mix is powdered in a powdering unit, to obtain the antimicrobial polymer powder coating. In an embodiment, the powdering unit is grinder.
At step 412, the antimicrobial polymer powder coating is layered over the substrate, by a layering unit. The layering unit in an embodiment can be done through electrostatic spray gun.
At step 416, the antimicrobial polymer powder coating is cured at 150 Deg C to 300 Deg C. The curing can be done by heating or irradiation. During heating the powder gets fused. The curing duration generally range from 2 minutes to 15 minutes.
For the case of coil coating method for making the antimicrobial substrate remains the same as mentioned in the method (400) with steps (404-416) except, the coating mix extrusion in the polymer extruder and powdering step in powdering unit.
Also, the layering over the substrate is dissimilar vis-à-vis the powder coating as it uses roll coater (layering unit).
The curing for the coil coating is also done at 150 Deg C to 300 Deg C. The curing can be done by heating or irradiation. During heating the powder gets fused. The curing duration generally range from 2 minutes to 15 minutes.

It is to be appreciated that the flash point of the PCMX is around 120-140 deg. C. But the curing temperature for powder deposition is around 200-300 deg. C. During homogenisation, the PCMX establishes a strong bonding with the coating, which helps in securing the PCMX in such a high temperature, thereby imparting longevity to antimicrobial nature of the coating. The bonding also helps in preventing the leaching of the coating.
Experimental Analysis:
The performance of the coating is represented by the examples below. The percentage mentioned in description and examples are in weight %.
The JIS Z 2801 test method is used to evaluate the performance of the product.
JIS Z 2801: This Japanese standard is used to evaluate the antimicrobial efficacy and growth activity over the surface of the polymer coated substrate. In this standard test method two kind of bacterial strain Staphylococcus aureus (ATCC6538P) and Escherichia coli (ATCC8739) used to see the killing capability of the coating surface. The Staphylococcus aureus belongs to gram positive category while Escherichia coli belongs to gram negative category.
The test conditions are mentioned below:
Neutraliser used: Buffered saline with Tween 80-0.01 %
Contact time: 24 hours at 370C
Incubation temperature: 370C for bacteria
Media and reagent: Soyabean-casein digest agar for bacteria
The sample of the coating are prepared with three chemistries (one with PCMX, with amorphous silver and their mixture) to evaluate the performance of the coating for microbe resistance or killing efficiency.
The developed antimicrobial polymer powder coating (Table 1 to Table 6) and coil coating (Table 7 to Table 10) was developed as per Table 1 and deposited on galvanised steel sheet coupon sample using electrostatic spray gun. Afterwards the curing was performed using heating at elevated temperature ranging from 150-3000C.
As shown in Table 1, the Untreated sample had 54.03 % bacteria left after 24 hrs., whereas the treated sample (powder coated) with PCMX had remained only 0.01%.
Table 1
Composition Amount in wt% Type of Resin Result Untreated Result treated
Resin 65 Polyester, Epoxy, Acrylic, Polyurethane, Polyvinyl chloride, PVDF %age of bacteria remained on sample after 24 hrs (54.03%)
As per JIS Z 2801 %age of bacteria killed on sample after 24 hrs (99.99%)
As per JIS Z 2801
Hardener 8
Filler 6
Pigments 18
Additive 2.2
PCMX 0.8
Amorphous silver 0
As shown in Table 2, the Untreated sample had 54.03 % bacteria left after 24 hrs., whereas the treated sample (powder coated) with Amorphous silver had remained only 0.01%.
Table 2
Composition Amount in wt% Type of Resin Result Untreated Result treated
Resin 65.2 Polyester, Epoxy, Acrylic, Polyurethane, Polyvinyl chloride, PVDF %age of bacteria remained on sample after 24 hrs (54.03%)
As per JIS Z 2801 %age of bacteria killed on sample after 24 hrs (99.99%)
As per JIS Z 2801
Hardener 8
Filler 6
Pigments 18
Additive 2
PCMX 0
Amorphous silver 0.8
As shown in Table 3, the Untreated sample had 54.03 % bacteria left after 24 hrs., whereas the treated sample (powder coated) with mix of Amorphous silver and PCMX had remained only 0.01%.

Table 3
Composition Amount in wt% Type of Resin Result Untreated Result treated
Resin 65 Polyester, Epoxy, Acrylic, Polyurethane, Polyvinyl chloride, PVDF %age of bacteria remained on sample after 24 hrs (54.03%)
As per JIS Z 2801 %age of bacteria killed on sample after 24 hrs (99.99%)
As per JIS Z 2801
Hardener 8
Filler 6
Pigments 18
Additive 2
PCMX 0.5
Amorphous silver 0.5
As shown in Table 4, the Untreated sample had 54.03 % bacteria left after 24 hrs., whereas the treated sample (powder coated) with mix of Amorphous silver and PCMX had remained only 0.01%.
Table 4
Composition Amount in wt% Type of Resin Result Untreated Result treated
Resin 64 Polyester, Epoxy, Acrylic, Polyurethane, Polyvinyl chloride, PVDF %age of bacteria remained on sample after 24 hrs (54.03%)
As per JIS Z 2801 %age of bacteria killed on sample after 24 hrs (99.99%)
As per JIS Z 2801
Hardener 8
Filler 6
Pigments 18
Additive 2
PCMX 1
Amorphous silver 1
Accelerated antimicrobial test (Tables 5): The accelerated corrosive conditions are simulated in laboratory by salt spray chamber where samples are exposed in 3.5% NaCl fog atmosphere as per ASTM B117. These simulated conditions mimic the long-term durability of the materials in real world scenario. The untreated and treated samples (powder coated) were exposed to salt spray chamber for 700 hours and afterwards it has been evaluated for the antimicrobial test as per JIS Z 2801. The results as per Table 5 suggest that the coating has got the durability antimicrobial property. The results are summarised in below table:
Table 5: Salt spray exposed samples antimicrobial tests
Composition Amount in wt% Type of Resin Result Untreated Result treated
Resin 65 Polyester, Epoxy, Acrylic, Polyurethane, Polyvinyl chloride, PVDF %age of bacteria remained on sample after 24 hrs (92.85).
The untreated samples were exposed to salt spray chamber for 700 hours and after words it has been evaluated for the antimicrobial test as per JIS Z 2801. %age of bacteria killed on sample after 24 hrs (98.82%)
The treated samples were exposed to salt spray chamber for 700 hours and after words it has been evaluated for the antimicrobial test as per JIS Z 2801.
Hardener 8
Filler 6
Pigments 18
Additive 2
PCMX 0
Amorphous silver 0.5
Accelerated abrasion test: In longer run during uses of the material it got rubbed of, aged, abraded. To simulate these conditions, 10-micron layer of the coating have been used. Afterward antimicrobial test as per JIS Z 2801 was performed. The results as per Table 6 suggest that the coating (powder coated) has got the antimicrobial property against the aged samples. The results are summarised in below table:
Table 6: Accelerated abrasion antimicrobial tests
Composition Amount in wt% Type of Resin Result Untreated Result treated
Resin 65 Polyester, Epoxy, Acrylic, Polyurethane, Polyvinyl chloride, PVDF %age of bacteria remained on sample after 24 hrs (74.80 %)
%age of bacteria killed on sample after 24 hrs (97.32)

Hardener 8
Filler 6
Pigments 18
Additive 2
PCMX 0
Amorphous silver 0.5

As shown in Table 7 below, the Untreated sample had 97.67 % bacteria left after 24 hrs., whereas the treated sample (coil coated) with Amorphous silver had remained only 0.09%.
Table 7: Antimicrobial test result for coil coating
Composition Amount in wt% Type of Resin Result Untreated Result treated
Resin 15-40 Regular modified polyester, Silicon modified polyester Epoxy, Polyurethane, Polyvinyl chloride, PVDF %age of bacteria remained on sample after 24 hrs (97.67 %)

As per JIS Z 2801 %age of bacteria killed on sample after 24 hrs (99.91)

As per JIS Z 2801
Hardener 10-25
Solvent 40-60
Filler 5-10
Pigments 5-20
Additive 1-3
PCMX 0
Amorphous silver 0.7
As shown in Table 8 below, the Untreated sample had 97.67 % bacteria left after 24 hrs., whereas the treated sample (coil coated) with mix of Amorphous silver and PCMX had remained only 0.01%.
Table 8: Antimicrobial test result for coil coating
Composition Amount in wt% Type of Resin Result Untreated Result treated
a coating mix of
Resin 15-40 Regular modified polyester, Silicon modified polyester Epoxy, Polyurethane, Polyvinyl chloride, PVDF %age of bacteria remained on sample after 24 hrs (97.67 %)

As per JIS Z 2801 %age of bacteria killed on sample after 24 hrs (99.99)

As per JIS Z 2801
Hardener 10-25
Solvent 40-60
Filler 5-10
Pigments 5-20
Additive 1-3
PCMX 0.7
Amorphous silver 0.7
As shown in Table 9 below, the Untreated sample had 97.67 % bacteria left after 24 hrs., whereas the treated sample (coil coated) with PCMX had remained only 0.07%.
Table 9: Antimicrobial test result for coil coating
Composition Amount in wt% Type of Resin Result Untreated Result treated
a coating mix of
Resin 15-40 Regular modified polyester, Silicon modified polyester Epoxy, Polyurethane, Polyvinyl chloride, PVDF %age of bacteria remained on sample after 24 hrs (97.67 %)

As per JIS Z 2801 %age of bacteria killed on sample after 24 hrs (99.93)

As per JIS Z 2801
Hardener 10-25
Solvent 40-60
Filler 5-10
Pigments 5-20
Additive 1-3
PCMX 0.7
Amorphous silver 0
Accelerated antimicrobial test (Tables 10): The accelerated corrosive conditions are simulated in laboratory by salt spray chamber where samples are exposed in 3.5% NaCl fog atmosphere as per ASTM B117. These simulated conditions mimic the long-term durability of the materials in real world scenario. The untreated and treated samples (coil coated) were exposed to salt spray chamber for 700 hours and afterwards it has been evaluated for the antimicrobial test as per JIS Z 2801. The results as per Table 10 suggest that the coating has got the durability antimicrobial property. The results are summarised in below table:
Table 10: Antimicrobial test result for coil coating
Composition Amount in wt% Type of Resin Result Untreated Result treated
a coating mix of
Resin 15-40 Regular modified polyester, Silicon modified polyester Epoxy,
Polyurethane, Polyvinyl chloride, PVDF %age of bacteria remained on sample after 24 hrs (87.50 %)

As per JIS Z 2801
The untreated samples were exposed to salt spray chamber for 700 hours and after words it has been evaluated for the antimicrobial test as per JIS Z 2801. %age of bacteria killed on sample after 24 hrs (99.99)
As per JIS Z 2801
The untreated samples were exposed to salt spray chamber for 700 hours and after words it has been evaluated for the antimicrobial test as per JIS Z 2801.
Hardener 10-25
Solvent 40-60
Filler 5-10
Pigments 5-20
Additive 1-3
PCMX 0
Amorphous silver 0.7

It is quite evident from the Tables that the antimicrobial polymer powder coating are safe and non-hazardous in for environment and health. Also, coating is economical the coating over the substrate has long life.
The active antimicrobial agent is inert wrt to temperature which is being used in melt extrusion and curing process of powder coating manufacturing and application operation.

Claims:

1. An antimicrobial polymer coating over a substrate comprising:
a coating mix;
an antimicrobial agent,
the antimicrobial agent being combination of para chloro meta xylenol (PCMX) and/or an amorphous silver, and
the antimicrobial agent being 0.01-3 wt% of the antimicrobial polymer coating for providing antimicrobial property.
2. The antimicrobial polymer coating as claimed in claim 1, wherein the coating mix is powder coating or coil coating.
3. The antimicrobial polymer coating as claimed in claims 1 and 2, wherein the coating mix comprises
a resin with 60-70 wt.% for powder coating or 15-40 wt% for coil coating for providing corrosion resistivity;
a hardener with 5-11 wt.% for powder coating or 10-25 wt.% for coil coating for crosslinking to the resin;
a filler with 4-8 wt.% for powder coating or 5-10 wt.% for coil coating for providing abrasion resistance and porosity reduction;
a pigments with 12-22 wt.% for powder coating or 5-22 wt.% for coil coating for colouring, hammer-tone, metallic structured finish;
an additive with 1-3 wt.% for flow control; and
optionally a solvent 40-60 wt.% for coil coating for coating transfer over the substrate.
4. The antimicrobial polymer powder coating as claimed in claim 3, wherein the resin is one or in combination(s) of Silicon modified polyester (SMP), Regular modified polyester (RMP), polyvinylidene fluoride (PVDF), Polyvinylchloride (PVC), Polyurethane (PU), Epoxy, Polyester, Polyurethane, Polyninyl chloride, Epoxy chemistry, thermoset polymer of TGIC (triglycidyl isocyanurate) / Non-TGIC polyester or polyester.
5. The antimicrobial polymer powder coating as claimed in claim 3, wherein the hardener is one or in combination(s) of Polyisocyanates, Anhidrides, amines and polyphenols.
6. The antimicrobial polymer powder coating as claimed in claim 3, wherein the filler is one or in combination(s) of Barium sulfate, Mica, Calcium carbonate (calcite), Calcium manganese carbonate (dolomite), Wollastonite, Kaolin.
7. The antimicrobial polymer powder coating as claimed in claim 3, wherein the pigment is one or in combination(s) of titanium dioxide, red oxide, yellow oxide, carbon black, aluminium flakes.
8. The antimicrobial polymer powder coating as claimed in claim 3, wherein the additive is one or in combination(s) of acrylics and silica.
9. The antimicrobial polymer powder coating as claimed in claim 3, wherein the solvent is one or in combination(s) of Xylene, Toulene, isopropyl alcohol, Acetonitrile, Benzene, dibasic ester.
10. The antimicrobial polymer powder coating as claimed in claim 1, wherein the substrate is steel or galvanised steel or aluminium or wood or plastic or Galvalume or Galfan, or Magizinc or Al-Si coated steel.
11. The antimicrobial polymer powder coating as claimed in claim 1, wherein size of amorphous silver-based glass material is 10 nm to 40 microns.
12. An antimicrobial substrate (300) comprising:
a substrate (304); and
an antimicrobial polymer coating (308) over the substrate, the antimicrobial polymer coating comprising
a coating mix and an antimicrobial agent,
the antimicrobial agent being a combination of para chloro meta xylenol (PCMX) and/or an amorphous silver, and
the antimicrobial agent being 0.01-3 wt% of the antimicrobial polymer coating for providing antimicrobial property.
13. The antimicrobial substrate as claimed in claim 12, wherein size of the antimicrobial agent is 0.01 to 0.5 times the thickness of the antimicrobial polymer coating.
14. The antimicrobial substrate as claimed in claim 12, wherein the substrate is steel or galvanised steel or aluminium or wood or plastic or Galvalume or Galfan, or Magizinc or Al-Si coated steel.

15. A method of making an antimicrobial substrate, the method comprising:
preparing a coating mix in a homogenizing chamber;
adding an antimicrobial agent to the coating mix in the homogenizing chamber;
the antimicrobial agent being combination of para chloro meta xylenol (PCMX) and/or an amorphous silver, the antimicrobial agent being 0.01-3 wt% of the antimicrobial polymer coating for providing antimicrobial property’
layering the antimicrobial polymer coating over a substrate, by a layering unit; and
curing the antimicrobial polymer coating at 150 Deg C to 300 Deg C.
16. The method as claimed in claim 15, wherein the curing is done for 2-15 minutes
17. The method as claimed in claim 15, wherein the substrate is steel or galvanised steel or aluminium or wood or plastic or Galvalume or Galfan or Magizinc or Al-Si coated steel.
18. The method as claimed in claim 15, wherein the layering unit is electrostatic spray gun or roll coater.
19. The method as claimed in claim 15, wherein the coating mix comprises of
a resin with 60-70 wt.% for powder coating or 15-40 wt.% for coil coating for providing corrosion resistivity;
a hardener with 5-11 wt.% for powder coating or 10-25 wt.% for coil coating for crosslinking to the resin;
a filler with 4-8 wt.% for powder coating or 5-10 wt.% for coil coating for providing abrasion resistance and porosity reduction;
a pigments with 12-22 wt.% for powder coating or 5-22 wt.% coil coating for colouring, hammer-tone, metallic structured finish; and
an additive with 1-3 wt.% for flow control; and
optionally a solvent 40-60 wt.% for coil coating for coating transfer over the substrate.
20. The method as claimed in claim 15, wherein the curing is done by heating.