Additive masterbatch

Abstract

Described herein are compositions comprising at least one organic salt and at least one organic acid for imparting antimicrobial activity to a plastic material. Methods for making the same, and uses of the same for microbial control, are also disclosed.

Description

[0001] ADDITIVE MASTERBATCH

[0002] The present invention relates to the incorporation of antimicrobial agents into or onto plastics or polymer material, and the provision of an additive masterbatch that imparts antimicrobial properties to a plastic or polymer material when added to such a material.

[0003] A masterbatch is a concentrate that is used to impart properties, such as colour (known as a colour masterbatch), or antimicrobials and UV, humidity or temperature resistance (known as additive masterbatches), to polymers during the manufacturing process. The composition of a masterbatch is called its recipe.

[0004] A masterbatch, also termed a polymeric concentrate, is a concentrated mixture of one or more additives, or active components, blended and extruded together in a carrier matrix that is used to add the additive(s) or active component(s) to a final polymer or plastic product. After extrusion, the extrudate is cooled, cut and formed into granules, mini beads, pellets or powders depending on its destined application. The carrier matrix may be resin, wax or a polymer such as polyethylene (PE) or polypropylene (PP), ethylene vinyl acetate (EVA), etc. that is compatible with the polymer or plastics material into which the masterbatch is added and diluted. The additive in a masterbatch is encapsulated in the carrier material. This encapsulation reduces or, in many cases, eliminates any dangerous properties of an additive, as well as protecting temperature-sensitive additives during the final product manufacturing process. Encapsulation also protects an additive from exposure to humidity, temperature and UV during storage.

[0005] Masterbatches are added or “let down” into a raw polymer or plastics material and are passed through a blending process which feeds into a moulding or extruding machine where the final plastic product is made.

[0006] An advantage of imparting particular properties to a polymer by way of a masterbatch, compared to adding one or more compounds directly, is that masterbatches are highly concentrated. This not only saves on raw component bulk and expense but also allows a higher accuracy of dosing of expensive components and, thus, minimal chance of variance during the manufacturing process of the final product. A masterbatch also provides a form that results in consistent dispersal of actives in a finished polymer product, as well as having a long shelf life due to being in solid form and being solvent-free. A masterbatch typically contains 40% to 65% additives, but the range may be from 15% to 80%. Furthermore, melting processes are improved because the carrier in a masterbatch is matched with the polymer(s) into which the masterbatch is added and diluted.

[0007] Antimicrobial masterbatches are well known but most are metal based systems using the likes of silver, zinc and copper salts which exhibit high thermal stability but limited antimicrobial activity. For example, US 2016 / 0135470 describes the masterbatches, concentrates and / or intermediates containing copper iodide as having broad-spectrum, fast acting antimicrobial activity. US 2008 / 0306183 discloses polyolefin or polyester fibres that include silver as an antimicrobial agent. However, the additional safety and environmental concerns of metal particles have caused manufacturers and consumers to turn from these technologies and seek alternative / naturally inspired substitutes. US 2017 / 0240720 is directed to an antimicrobial masterbatch polymer composition in which the antimicrobial property is provided by the inclusion of chlorinated phenols (Triclosan derivatives) or quaternary ammonium compounds. The use of triclosan in food storage containers was banned in the European Union in 2010. In an alternative, US 2003 / 0235605 describes a polymeric article in which the antimicrobial property is effected by the release of an antimicrobial gas, such as chlorine dioxide, chlorine, hydrogen peroxide, and sulphur dioxide, on exposure to light and / or humidity.

[0008] Another drawback for these technologies is the growing rise in antimicrobial resistance due to overuse of a single active for a long time.

[0009] WO 2021 / 138144 describes the inclusion of some organic acids in plastic substrates. However, the Applicant finds that not all organic acids are effective because not all are sufficiently stable at the temperatures required for plastic processing, namely temperatures of about 200°C and above.

[0010] It is against this background that the present invention has been devised. In particular, the present invention encompasses a composition including two or more chemical components that imparts antimicrobial properties to a thermoplastic material when added and diluted therewith and is sufficiently efficacious against both gram-negative and gram-positive bacteria, cost-effective, and safe. The inclusion of more than one antimicrobial component produces a superior antibacterial efficacy through a synergistic effect between the components, as well as the components acting via different antimicrobial mechanisms.

[0011] Specifically, the present invention resides in a composition for imparting antimicrobial properties to a plastic material, the composition comprising: at least one organic alkaline metal salt or alkaline earth metal salt; and at least one organic acid. The at least one salt and at least one acid together impart antimicrobial properties to the composition.

[0012] A number of organic acids are known to have antimicrobial activity. For example, some naturally occurring acids are known to pass easily through the plasma membrane of a bacterial / fungal cell and, once inside, dissociates and releases protons which change the pH inside the cell thereby inhibiting essential microbial metabolic reactions and eventually killing the bacterial / fungal cell. However, cells might be able to repair the damage caused by released protons to a certain extent. Hence, it is advantageous to combine an acid with another antimicrobial molecule with a different mechanism of action. Alkaline metal and alkaline earth metal salts are known to be antimicrobial via changing the osmotic pressure in a bacterial / fungal cell. Through the use of a combination of actives, an improved antimicrobial efficacy can be achieved, in addition to reducing the ability for the microbe to gain antimicrobial resistance. For the avoidance of doubt, in the context of the present invention the term “antimicrobial” encompasses bacteria, fungi and viruses.

[0013] The inventors have surprisingly found that organic salts and organic acids that show no to minimal antimicrobial activity alone at the concentrations (<5%) that are suitable for masterbatch production show substantial antimicrobial activity when combined, thanks to a synergistic effect between the two components.

[0014] Expressed in another way, the present invention also resides in a composition for imparting antimicrobial properties to a plastic material, the composition consisting essentially of: at least one organic alkaline metal salt or alkaline earth metal salt; and at least one organic acid, in which the at least one salt and at least one acid together impart antimicrobial properties to the composition. The term “consisting essentially of” is used in the context to denote a composition in which the only active components in the composition are the at least one organic alkaline metal salt or alkaline earth metal salt and at least one organic acid. It will be understood that the composition may include additional components present in amounts such that the antimicrobial properties of the at least one salt and acid are not affected.

[0015] In one example, the at least one organic alkaline metal salt or alkaline earth metal salt may have a thermal stability above about 150°C. Expressed in another way, the at least one organic alkaline metal salt or alkaline earth metal salt may have a thermal stability up to about 230°C. In this way, the salt is able to withstand the temperatures required for processing of plastics. In another example, the at least one organic alkaline metal salt or alkaline earth metal salt may be selected from carboxylate, sorbate, sulphite, metabisulphite, benzoate, nitrite, acetate, or stearate. Benzoate, carboxylate and sorbate salts have been found to be particularly suitable. In one embodiment, the salt is benzoate.

[0016] In a further example, the metal in the at least one organic alkaline metal salt or alkaline earth metal salt may be selected from Na+, K+, Ca2+, Mg2+, Ti2+, Ti4+, and Zn2+, of which sodium, potassium, calcium and zinc (II) have been found to be particularly suitable. Examples of suitable salts include potassium sorbate, sodium benzoate, sodium stearate, sodium nitrite, and disodium EDTA. Suitably, the salt is sodium benzoate.

[0017] In a yet further example, the at least one organic acid may be a substantially non-volatile, or high boiling point, carboxylic acid. This ensures that the acid does not evaporate before the plastic has been melted. In particular, the acid should be able to withstand temperatures of between about 100°C and about 250°C, or above about 150°C. Examples of organic acids that are not able to withstand such temperatures include acetic acid, propionic acid and lactic acid, all of which are low boiling point carboxylic acids.

[0018] Examples of suitable acids include EDTA, disodium EDTA, tartaric acid, malic acid, citric acid, benzoic acid, stearic acid, caffeic acid, p-coumaric acid, ferulic acid, gallic acid, sorbic acid, salicylic acid, chlorogenic acid, oxalic acid, butyric acid, folic acid, sorbic acid, fumaric acid, and combinations thereof. In one embodiment the acid is tartaric acid.

[0019] In one embodiment, the organic salt is potassium sorbate and the organic acid is EDTA. In one embodiment, the organic salt is sodium benzoate and the organic acid is EDTA. In one embodiment, the organic salt is sodium nitrite and the organic acid is EDTA. Some organic acids having at least two carboxylic acid groups can behave as both a carboxylic acid component and a carboxylate salt if at least one of the acids is neutralised to possess a metal salt (such as sodium and potassium). One example is disodium EDTA (dEDTA). Thus, in one embodiment, the organic salt is sodium nitrite and the organic acid is dEDTA. In one embodiment, tartaric acid and dEDTA may be used in combination. Suitably, the organic salt is sodium benzoate and the organic acid is tartaric acid.

[0020] In a particular example, the at least one organic alkaline metal salt or alkaline earth metal salt and at least one organic acid are present in the composition in a ratio of between 1 :2 and 5:1. The ratio of salt:acid may be between 2:1 and 5:1. The ratio of salt:acid is suitably between 3:1 and 4:1.

[0021] Optionally, the plastic material may be a thermoplastic or thermoplastic elastomer. In an alternative, the plastic material may be a thermosetting plastic.

[0022] In another example, the composition may further comprise a thermoplastic or thermoplastic elastomer carrier. In such an example, the plastic material may comprise the same material as the thermoplastic carrier.

[0023] Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Their plasticity makes it possible for plastics to be moulded, extruded or pressed into solid objects of various shapes. Most modern plastics are derived from fossil fuel-based chemicals such as natural gas or petroleum, but more recent industrial methods use variants made from renewable materials, including corn and cellulose derivatives.

[0024] A thermoplastic, or thermosoftening plastic, is a plastic polymer material that softens and becomes pliable or mouldable when heated and solidifies on cooling. Once softened, a thermoplastic may be processed using methods such as extrusion, injection moulding, thermoforming and blow moulding. These types of plastics can generally be reshaped or remoulded numerous times and, once cooled, show no changes in chemical property after being heated and cooled multiple times, making them easily recyclable and reusable.

[0025] Examples of thermoplastics include: polyolefins and copolymers thereof; polypropylene (PP); polyethylene including ultra-high molecular weight polyethylene (LIHMWPE), high density polyethylene (HDPE), medium density polyethylene (MDPE), linear low density polyethylene (LLDPE), and low density polyethylene (LDPE); polyesters including lactone-based polymers such as poly(lactide) (PLA), polycaprolactone (PCL), valeralactone, glycolide, and pentadecalactone; polyoxymethylene (POM); polyvinyl chloride (PVC); acrylics including ester derivatives (PAc) thereof; poly(methyl methacrylate) (PMMA) or acrylic; ethylene-vinyl acetate (EVA); polyvinyl alcohol (P A) acrylonitrile-butadiene-styrene (ABS); acrylonitrile styrene acrylate (ASA); styrene acrylonitrile resin (SAN); and combinations thereof.

[0026] Thermoplastic elastomers (TPE), sometimes referred to as thermoplastic rubbers (TPR), are a class of copolymers or a physical mix of polymers (usually a plastic and a rubber) that consist of materials with both thermoplastic and elastomeric properties. Thermoplastic elastomers show advantages typical of both rubbery materials and plastic materials. To qualify as a thermoplastic elastomer, a material must have three essential characteristics: i) the ability to be stretched to moderate elongations and, upon the removal of stress, return to something close to its original shape; ii) be processable as a melt at an elevated temperature; and show no significant creep (slow deformation under persistent mechanical stresses).

[0027] Examples of thermoplastic elastomers include thermoplastic polyurethanes (TPU); styrenic block copolymers (TPS); thermoplastic polyolefinelastomers (TPO); thermoplastic copolyester (TPC); unclassified thermoplastic elastomers (TPZ); and combinations thereof.

[0028] It will be appreciated that the carrier may be selected to be compatible with the plastic material into which the composition may be incorporated as a masterbatch or applied to as a coating. The carrier protects the active ingredients to minimise the loss of activity in components that may be thermally sensitive. Examples of plastic materials encompassed by the present invention include those listed as a thermoplastic or thermoplastic elastomer carrier. The carrier may be polypropylene, such as polypropylene resin.

[0029] The carrier makes up the bulk of the composition and may be present in an amount of between 50 wt% and about 97 wt%, between about 80 wt% and about 97wt%, between about 90 wt% and 97 wt%, or between about 95 wt% and 97 wt%.

[0030] The composition may have an active concentration (i.e. a concentration of at least one organic alkaline metal salt or alkaline earth metal salt and at least one organic acid) of about 0.5-5 wt%, such as about 1-4 wt% or about 2-3 wt%. The concentration of the at least one organic alkaline metal salt or alkaline earth metal salt in the composition may be about 1 wt% or about 2 wt%. The concentration of the at least one organic acid in the composition may be about 1 wt% or about 2 wt%. The composition may comprise about 2 wt% of the at least one organic alkaline metal salt or alkaline earth metal salt and about 2 wt% of the at least one organic acid.

[0031] The at least one organic alkaline metal salt or alkaline earth metal salt and at least one organic acid may be present in the composition in a powdered form. A powdered form has a larger surface area which may improve antimicrobial activity. In addition, powders finer than 50 pm are below the best eye resolution and so cannot be seen in the final product. In another example, the composition is in a solid form, such as granules, mini beads, pellets or a powder. In this way, the composition is in a form particularly suitable for use as a polymeric concentrate or masterbatch, or a polymeric binder for coatings.

[0032] Where the composition is for use as a polymeric binder for coatings, the composition may further include additional components that enable the specified use. Examples include binders, cross-linkers, stabilisers and / or compatibilisers which may be added in any combination with any suitable homopolymer, copolymer or elastomer.

[0033] In a particular example, the polymeric concentrate or masterbatch may have an active concentration (i.e. a concentration of at least one organic alkaline metal salt or alkaline earth metal salt and at least one organic acid) of 1% to 60%, or 5% to 40% by weight of the composition. Alternatively, the polymeric binder may have an active concentration of about 0.1% to about 40%, or 0.1% to about 10% based on solution % solids. The polymeric binder may be aqueous, non-aqueous, or contain a trace amount of co-solvent. The binder may also be a reactive or non-reactive binder for use as a coating. It will be appreciated that a non-reactive binder simply uses physical interactions (conventional chemical interaction) to hold on to a surface, while a reactive binder causes a reaction which generates a continuous surface or coating on a substrate.

[0034] In a particular example, the carrier and at least one organic alkaline metal salt or alkaline earth metal salt and at least one organic acid may be combined as powders before being heated and extruded into granules, mini beads, pellets or a powder. By way of illustration, the composition may be prepared by mixing dry powders of the organic salt and organic acid with polypropylene resin, before being either: 1) heat pressed at 170°C, or 2) extruded at 180°C then heat pressed at 170°C.

[0035] Also encompassed by the present invention is a masterbatch comprising, or comprising essentially of, a composition as described and defined herein.

[0036] Further encompassed by the present invention is the use of a composition as described and defined here as a masterbatch for incorporation into a plastic material, or a polymeric binder for application to a surface of a plastic material.

[0037] Expressed in another way, the present invention also resides in a method for imparting antimicrobial properties to a plastic material, in which the method comprises either i) incorporating a composition as described and defined herein into the plastic material, or ii) applying a composition as described and defined herein onto a surface of the plastic material. Incorporation into the plastic material is optimally achieved by having the composition in the form of a polymeric concentrate or a masterbatch. Addition or application of the composition to a surface of a plastic material is best achieved by having the composition in the form of a polymeric binder or coating.

[0038] It will be appreciated that the most effective incorporation or application of the active components is achieved where the polymeric concentrate, masterbatch or polymeric binder includes a thermoplastic or thermoplastic elastomer carrier that is compatible for combining with the plastic material. Examples of suitable thermoplastic or thermoplastic elastomer carriers and plastic materials are provided herein above.

[0039] In an example, the polymeric concentrate or masterbatch may have an active concentration of about 1% to about 60%, or about 5% to about 40%, or about 0.5% to about 10% by weight of the composition. Alternatively, the polymeric binder or coating may have an active concentration of about 0.1% to about 10% based on solution % solids.

[0040] It will be appreciated that the compositions, methods, use, masterbatch and coatings described and defined herein have many applications. Examples of products that benefit from having an antimicrobial profile include: conventional and technical textiles, facemasks, high performance non-woven materials such as filters, ventilation systems, surgical gowns, wet wipes, nappies, hygienic pads, wound dressings, food packaging such as plastic bags, vacuum packing, cling and stretch films, rigid and soft containers, bottles and lids for foods and beverages, inserts for packaging and articles including food packaging, household products such as storage boxes, containers, domestic liquids bottles, waste bins and dustbins, gloves and thin film coatings for various applications including but not limited to hospitals, industrial kitchens, restaurants, mobile telephones or similar devices, touchscreens, keypads, keyboards, buttons and knobs, handles, screen protectors, furniture such as a seat, chair, toilet seat, cup or mug, worktop, banknotes, upholstery. High contact materials and appliances include kitchen appliances, doors, taps or faucets, steering wheels, hospital appliances, medical devices, medical components.

[0041] The invention will now be described further with reference to the following, non-limiting experiments and figures, in which:

[0042] Figure 1 : Antibacterial activity of formulations of the present invention in polypropylene against gram-positive bacterium Staphylococcus aureus (Figure 1A) and gram-negative bacterium Escherichia coli. (Figure 1B). Samples are: (1) Polypropylene only (control); (2) sodium benzoate (2%); (3) potassium sorbate (2%); (4) EDTA (1%); (5) sodium benzoate (2%) + EDTA (1%); (6) potassium sorbate (2%) + EDTA (1%).

[0043] Figure 2: Antibacterial activity of formulations of the present invention in polypropylene against gram-positive bacterium Staphylococcus aureus (Figure 2A) and gram-negative bacterium Escherichia coli. (Figure 2B). Samples are: (1) Polypropylene only (control); (2) sodium benzoate (2%); (3) tartaric acid (2%); (4) sodium benzoate (1.5%) + tartaric acid (1.5%); (5) sodium benzoate (2%) + tartaric acid (1%); (6) sodium benzoate (2.25%) + tartaric acid (0.75%).

[0044] Figure 3. Antibacterial activity of formulations of the present invention in polypropylene against gram-positive bacterium Staphylococcus aureus. Samples are: (1) Polypropylene only (control); (2) EDTA (1%); (3) sodium nitrite (2%); (4) sodium nitrite (2%) + EDTA (1%). Figure 4: Antibacterial activity of formulations of the present invention in polypropylene against gram-negative bacterium Escherichia coli. Samples are: (1) Polypropylene only (control); (2) sodium nitrite (2%); (3) dEDTA (2%); (4) sodium nitrite (2%) + dEDTA (2%). Figure 5: Antibacterial activity of formulations of the present invention in polypropylene against gram-negative bacterium Escherichia coli Samples are: (1) Polypropylene only (control); (2) tartaric acid (2%); (3) dEDTA (2%); (4) tartaric acid (2%) + dEDTA (2%).

[0045] METHODS

[0046] Samples were prepared by mixing dry powders with polypropylene resin (Impact Polypropylene, Sabie PHC31), before being either: 1) heat pressed at 170°C, or 2) extruded at 180°C then heat pressed at 170°C.

[0047] All samples were tested for a bacterial contact time of 24 h following a modified ISO 22196 standard.

[0048] RESULTS

[0049] Experiment 1

[0050] In this experiment, the antibacterial activity of selected organic metal salts and organic acids, as well as combinations thereof, was tested.

[0051] It was found that blending a carboxylic acid-based component with a salt-based component had a substantially increased antibacterial activity compared to each component alone. As illustrated in Figure 1, ethylenediaminetetraacetic acid (1%, Sigma Aldrich, purity >99.4%), a well-known chelating agent which improves antibacterial activity, was combined with the carboxylate salts potassium sorbate (2%, Sigma Aldrich, purity >99%) or sodium benzoate (2%, Sigma Aldrich, purity 99%). EDTA and each salt alone produced low to no activity but, when combined, showed a substantial antibacterial effect against both gram-positive bacterium, Staphylococcus aureus (S. aureus), (99.99% reduction) and gram-negative bacterium, Escherichia coli (E. coli) (99.3% reduction).

[0052] Experiment 2

[0053] In this experiment, the ratio of salt to acid was tested.

[0054] It was found that there was a dependence on the ratio between the salt and acid on the antibacterial efficacy. For example, as shown in Figure 2, a combination of sodium benzoate and tartaric acid (Thermoscientific, purity +99%) showed that a higher ratio of sodium benzoate to tartaric acid typically showed improved antibacterial efficacy against both grampositive bacterium, S aureus, (99.999% reduction) and gram-negative bacterium, E. coli (99.9999% reduction).

[0055] Experiment 3

[0056] This experiment investigated whether other organic salts, besides carboxylate salts, were similarly as effective as antibacterial agents when combined with an organic acid.

[0057] As shown in Figure 3, sodium nitrite (2%, Thermoscientific, purity 98%) in combination with EDTA (1%) was effective against the gram-positive bacterium S aureus (99.97% reduction). Whilst carboxylate salts were tested (Figure 1), evidence from this experiment showed that other salts, including sodium nitrite, also work in combination with acids (Figure 3).

[0058] Experiment 4

[0059] Some organic acids having at least two carboxylic acid groups can behave as both a carboxylic acid component and a carboxylate salt if at least one of the acids is neutralised to possess a metal salt (such as sodium and potassium). The example tested in this experiment was disodium EDTA (dEDTA, Invitrogen, UltraPure™), which presents two free carboxylic acids and two sodium carboxylate salts. Referring to Figure 4, dEDTA (2%) alone performed poorly against E. coli but, in combination with sodium nitrite (2%) showed a significant improvement in antibacterial efficacy (99.87% reduction).

[0060] Experiment 5

[0061] This experiment tested the effectiveness of dEDTA (2%) with the organic acid, tartaric acid (2%). As shown in Figure 5, while neither the salt nor acid alone showed much activity against the gram-negative bacterium, E. coli, the combination of the two was seen to kill more than 99% of the bacterial cells.

Claims

1. CLAIMS1. A composition for imparting antimicrobial properties to a plastic material, the composition comprising:- at least one organic alkaline metal salt or alkaline earth metal salt; and- at least one organic acid, wherein the at least one salt and at least one acid together impart antimicrobial properties to the composition.

2. The composition according to claim 1 consisting essentially of:- at least one organic alkaline metal salt or alkaline earth metal salt; and- at least one organic acid, wherein the at least one salt and at least one acid together impart antimicrobial properties to the composition.

3. The composition according to claim 1 or claim 2, wherein the at least one organic alkaline metal salt or alkaline earth metal salt has a thermal stability above about 150°C.

4. The composition according to any one of claims 1 to 3, wherein the at least one organic alkaline metal salt or alkaline earth metal salt has a thermal stability up to about 230°C.

5. The composition according to any one of claims 1 to 4, wherein the at least one organic alkaline metal salt or alkaline earth metal salt is selected from carboxylate, sorbate, sulphite, metabisulphite, benzoate, nitrate, acetate, or stearate.

6. The composition according to any one of claims 1 to 5, wherein the metal in the at least one organic alkaline metal salt or alkaline earth metal salt is selected from Na+, K+, Ca2+, Mg2+, Ti2+, Ti4+, and Zn2+.

7. The composition according to any one of claims 1 to 6, wherein the at least one organic acid is a substantially non-volatile carboxylic acid.

8. The composition according to any one of claims 1 to 7, wherein the acid is selected from EDTA, disodium EDTA, tartaric acid, malic acid, citric acid, benzoic acid, stearic acid, caffeic acid, p-coumaric acid, ferulic acid, gallic acid, sorbic acid, salicylic acid, chlorogenic acid, oxalic acid, butyric acid, folic acid, sorbic acid, fumaric acid, and combinations thereof.

9. The composition according to any one of claims 1 to 8, wherein the salt and acid are present in the composition in a ratio of between 1:2 and 5:1.

10. The composition according to any one of claims 1 to 9, wherein the plastic material is a thermoplastic or thermoplastic elastomer.

11. The composition according to any one of claims 1 to 10, wherein the composition further comprises a thermoplastic or thermoplastic elastomer carrier.

12. The composition according to claim 11, wherein the plastic material comprises the same material as the thermoplastic carrier.

13. The composition according to claim 11 or claim 12, wherein the thermoplastic or thermoplastic elastomer is selected from one or more of polyolefins and copolymers thereof; polypropylene (PP); polyethylene including ultra-high molecular weight polyethylene (LIHMWPE), high density polyethylene (HDPE), medium density polyethylene (MDPE), linear low density polyethylene (LLDPE), and low density polyethylene (LDPE); polyesters including lactone-based polymers such as poly(lactide) (PLA), polycaprolactone (PCL), valeralactone, glycolide, and pentadecalactone; polyoxymethylene (POM); polyvinyl chloride (PVC); acrylics including ester derivatives (PAc) thereof; poly(methyl methacrylate) (PMMA) or acrylic; ethylene-vinyl acetate (EVA); polyvinyl alcohol (P A) acrylonitrile-butadiene- styrene (ABS); acrylonitrile styrene acrylate (ASA); styrene acrylonitrile resin (SAN); thermoplastic polyurethanes (TPU); styrenic block copolymers (TPS); thermoplastic polyolefinelastomers (TPO); thermoplastic copolyester (TPC); unclassified thermoplastic elastomers (TPZ); and combinations thereof.

14. The composition according to any one of claims 11 to 13, wherein the carrier is present in the composition in an amount of between about 50 wt% and about 97 wt%, between about 80 wt% and about 97wt%, between about 90 wt% and 97 wt%, or between about 95 wt% and 97 wt%.

15. The composition according to any one of claims 1 to 14, wherein composition is in a solid form.

16. The composition according to any one of claims 1 to 15, wherein the composition is in a form of a polymeric concentrate or masterbatch, or a polymeric binder for a coating.

17. The composition according to claim 16, wherein the polymeric concentrate or masterbatch has an active concentration of 1% to 60%, or 5% to 40% by weight of the composition, or the polymeric binder has an active concentration of about 0.1% to about 40% based on solution % solids.

18. The composition according to claim 16 or claim 17, wherein the polymeric binder is aqueous, non-aqueous, or contains a trace amount of co-solvent.

19. The composition according to any one of claims 16 to 18, wherein the polymeric binder is a reactive or non-reactive binder for use as a coating.

20. A masterbatch comprising, or comprising essentially of, a composition as claimed in any one of claims 1 to 19.

21. Use of a composition as claimed in any one of claims 1 to 19 as a masterbatch for incorporation into a plastic material, or a polymeric binder for application to a surface of a plastic material.

22. A method for imparting antimicrobial properties to a plastic material, the method comprising either i) incorporating into the plastic material, or ii) applying onto a surface of the plastic material, a composition as claimed in any one of claims 1 to 19.

23. The method according to claim 22, wherein the composition is incorporated into the plastic material as a polymeric concentrate or masterbatch or applied to the plastic material surface as a polymeric binder.

24. The method according to claim 23, wherein the polymeric concentrate, masterbatch or polymeric binder includes a thermoplastic or thermoplastic elastomer carrier that is compatible for combining with the plastic material.

25. The method according to any one of claims 22 to 24, wherein the polymeric concentrate or masterbatch has an active concentration of about 1% to about 60%, or about 5% to about 40%, or about 0.05% to about 10% by weight of the composition, or the polymeric binder has an active concentration of about 0.1% to about 40% based on solution % solids.

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