Subsequent Processing of the Compound and Polymeric Article. Let-down of the masterbatch of the invention into a polymer compound may be done during subsequent steps of reshaping by extrusion, molding, or calendering. Processing begins with melt-mixing the masterbatch with the base polymer resin followed by reshaping by extrusion, molding, or calendering, followed by natural or accelerated cooling to form the final plastic article desired.
In the case of molding, particularly injection molding, the reshaping step includes pressurized injecting, holding, and cooling steps before the plastic article is ejected, the cycle of which the time is being measured to determine cycle time. More specifically, the reshaping step comprises four substeps of 1 injecting the compound into a mold; 2 holding the compound in the mold to form the plastic article in the shape of the mold; 3 cooling the plastic article to permit the plastic article to be released from the mold while retaining shape of the mold; and 4 ejecting the final plastic article.
Subsequent extrusion or molding techniques are well known to those skilled in the art of thermoplastics polymer engineering.
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The antimicrobial masterbatches of the present invention can be let-down into polymers resins, with other ingredients, to make molded, calendered, extruded, thermoformed, or 3D printed antimicrobial articles. In the present invention, the migratory assisting agent is added for the purpose of migrating the antimicrobial agent to the surface of the polymer, and not for the known performance characteristics of that migratory assisting agent.
Therefore, the migratory assisting agent can oftentimes be used at lower levels than a person having ordinary skill in the art would use the migratory assisting agent if trying to exploit the additive for its known purpose, such as using an anti-static agent for its anti-static properties or a slip agent for its slip properties. The JIS Z method is designed to quantitatively test the ability of plastics to inhibit the growth of microorganisms or kill them, over a 24 hour period of contact. Control and test surfaces are inoculated with microorganisms, in triplicate, and then the microbial inoculum is covered with a thin, sterile film.
Automated Screening of Antimicrobial Polymers :: ChemViews Magazine :: ChemistryViews
Covering the inoculum spreads it, prevents it from evaporating, and ensures close contact with the antimicrobial surface. Inoculated, covered control and antimicrobial test surfaces are allowed to incubate undisturbed in a humid environment for 24 hours. After incubation, microbial concentrations are determined. The antimicrobial activity is calculated based on the reduction of microorganisms relative to initial concentrations as calibrated by the control surface.
Table 2 shows the ingredients used for the Comparative Examples and the Examples.
Table 5 shows the formulations of the Masterbatches and Table 6 shows the formulations of the Masterbatches let-down into the antimicrobial polymer compounds of the Comparative Examples A-D and Examples RPM To prepare Comparative Examples A-D and Examples , a percentage of each Masterbatch was let down into a base resin.
The Masterbatch was metered into the base resin in a co-rotating screw extruder through a side feeder to maintain the integrity of the material before pelletizing according to the conditions in Table 4.
EPA-approved antimicrobial polymer shown to remove, eradicate biofilm, slimy bacteria
The pelletized polymer compound was then injection molded to form 50 mil plaques. The test results are shown in Table 6. Comparative Examples A-D were prepared by letting down Masterbatches I-IV, which excluded any type of migratory additive, into the selected base resin. When tested for antimicrobial efficacy, Comparative Examples B and C failed to reach the minimum desirable log 2.
Comparative Example A failed to reach the minimum desirable log 2. Only Comparative Example D achieved at least the minimum desirable log 2. Examples added a migratory assisting agent to the Masterbatches V-IX.
Unexpectedly, Examples all demonstrated improved antimicrobial efficacy compared to the corresponding Comparative Examples, as discussed below. Although Example 1 used 0. In addition, Examples 7 and 8 in polycarbonate resin demonstrated a similar surprising increase in antimicrobial activity, and with Example 7 using less of the antimicrobial agents compared to Comparative Example C. Example 2 demonstrates the use of a migratory assisting agent with less antimicrobial agent in a styrene-nylon alloy. Compared to the control, Comparative Example B, Example 2 has significantly increased antimicrobial activity, even though it uses almost half of the amount of antimicrobial agent.
Finally Examples 3 and 4, which correspond to Comparative Example A for thermoplastic elastomers; and Examples 5 and 6, which correspond to Comparative Example D for polyolefins, show a significant increase in the antimicrobial activity with the use of a migratory assisting agent, even when using less of the antimicrobial agents in Examples 3 and 5.
Therefore, the migratory assisting agent permits antimicrobial surface protection of plastic articles more efficiently given a specific concentration of antimicrobial agent. That unexpected result allows for either the same amount of antimicrobial agent in the compound with increased surface efficacy or a reduced amount of antimicrobial agent in the compound with the same surface efficacy.
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The invention is not limited to the above embodiments. The claims follow. What is claimed is: 1. An antimicrobial masterbatch for thermoplastic compounds, comprising: a a polymer carrier. The masterbatch of claim 1 , wherein the antimicrobial agent is selected from metal ions in form of salts, oxides, complexes, and combinations thereof.
The masterbatch of claim 1 , wherein the migratory assisting agent will carry at least some of the antimicrobial agent to a surface of an article formed from the masterbatch. The masterbatch of claim 1 , wherein the polymer carrier is selected from the group consisting of polyolefins, polyamides, polyesters, poly meth acrylates, polycarbonates, poly vinyl halides , polyvinyl alcohols, polynitriles, polyacetals, polyimides, polyarylketones, polyetherketones, polyhydroxyalkanoates, polycaprolactones, polystyrenes, polyurethanes, polysulfones, polyphenylene oxides, polyphenylene sulfides, polyacetates, liquid crystal polymers, fluoropolymers, ionomeric polymers, thermoplastic elastomers, and copolymers of any of them and combinations of any two or more of them.
The masterbatch of claim 1 , wherein other additives are selected from the group consisting of anti-blocking agents; adhesion promoters; fungicides; mildewcides; anti-fogging agents; bonding, blowing and foaming agents; dispersants; fillers and extenders; fire and flame retardants and smoke suppressants; impact modifiers; initiators; lubricants; micas; pigments, colorants and dyes; plasticizers; processing aids; other slip or release agents; other anti-static agents; silanes, titanates and zirconates; stabilizers; stearates; ultraviolet light absorbers; viscosity regulators; waxes; and combinations of them.
The masterbatch of claim 1 , wherein the ingredients by weight percent of the masterbatch are listed below. Polymer carrier: An antimicrobial compound comprising the masterbatch of claim 1 and a base polymer resin. The antimicrobial compound of claim 7 , wherein the base polymer resin is selected from the group consisting of polyolefins, polyamides, polyesters, poly meth acrylates, polycarbonates, poly vinyl halides , polyvinyl alcohols, polynitriles, polyacetals, polyimides, polyarylketones, polyetherketones, polyhydroxyalkanoates, polycaprolactones, polystyrenes, polyurethanes, polysulfones, polyphenylene oxides, polyphenylene sulfides, polyacetates, liquid crystal polymers, fluoropolymers, ionomeric polymers, thermoplastic elastomers, and copolymers of any of them and combinations of any two or more of them.
Unearthing the Antimicrobial Properties of a Forgotten Polymer
The antimicrobial compound of claim 7 , further comprising additives selected from the group consisting of anti-blocking agents; adhesion promoters; fungicides; mildewcides; anti-fogging agents; bonding, blowing and foaming agents; dispersants; fillers and extenders; fire and flame retardants and smoke suppressants; impact modifiers; initiators; lubricants; micas; pigments, colorants and dyes; plasticizers; processing aids; other slip or release agents; other anti-static agents; silanes, titanates and zirconates; stabilizers; stearates; ultraviolet light absorbers; viscosity regulators; waxes; and combinations of them.
The antimicrobial compound of claim 7 , in the shape of a molded plastic article, an extruded plastic article, a calendered plastic article, a thermoformed plastic article, or a 3D printed plastic article. It also demonstrated stronger antimicrobial activity against 20 clinical strains of K. Multiple treatments with imipenem and gentamycin led to drug resistance in K. Additionally, the polymer showed potent anti-biofilm activity.
In a MDR K. The polymer treatment significantly alleviated lung injury, markedly reduced K. Given its potent in vivo antimicrobial activity, negligible toxicity and ability of mitigating resistance development, the polyionene may be used to treat MDR K. In this study, we report synthesis of antimicrobial polymers polyionenes and their use as antimicrobial agents for treatment of K. The polymer treatment also provides higher survival rate and faster bacterial removal from the major organs and the blood than the antibiotics.
Repeated use of the polymer does not lead to resistance development. More importantly, at the therapeutic dose, the polymer treatment does not cause acute toxicity. Given its in vivo efficacy and negligible toxicity, the polymer is a promising candidate for the treatment of MDR K. Read Article at publisher's site.
How does Europe PMC derive its citations network? Layer-by-layer deposition of antimicrobial polymers on cellulosic fibers : a new strategy to develop bioactive textiles. Gomes, Ana P. Mano, J. Queiroz, J.