Study On Antibacterial Properties And Safety Evaluation Of Antibacterial Polyethylene Packaging Sheets

Classification of antibacterial agents,ways to prepare antibacterial plastics,and applications of antibacterial agents in plastic packaging were reviewed.Based on the demand for multi-functional packaging,the antibacterial properties of antibacterial sheets with different antibacterial agents and the migration of antibacterial components in antibacterial plastics were studied,which helped people to understand the safety of food contact materials.Nano-TiO₂/Ag⁺was modified by titanate coupling agent,and its effect on the property of high-density polyethylene（HDPE）sheet was studied.Fourier transform infrared spectroscopy（FT-IR）,transmission electron microscopy（TEM）and X-ray diffraction（XRD）were used to compare characteristics of unmodified and modified nano-TiO₂/Ag⁺particles.Results showed that the lipophilic degree of the modified nano-TiO₂/Ag⁺powder was above 60%when the titanate coupling agent NDZ-201 was added by 2%.FT-IR investigation indicated that the titanate coupling agent was chemically bonded on the surface of nano-TiO₂/Ag⁺.Moreover,XRD study showed that the modification did not lead to structural changes of the powder.The dispersibility of nano-TiO₂/Ag⁺powder and its compatibility with HDPE have been significantly improved after the modification.LDPE sheets were prepared containing nano-silver,nano-zinc oxide and antioxidant 168.Anti-microbial properties of the sheets were tested by film coating method.The effects of multiple factors on antibacterial performances of plastic sheets were studied by orthogonal test design and Analysis of Variance.It was found that nano-silver and nano-zinc oxide powder have good antibacterial durability,and antioxidant 168 has no antibacterial property.However,nano-silver and nano-zinc oxide had no significant influence on antimicrobial properties of plastic sheet.Surprisingly,the antibacterial rate of LDPE sheets containing only anti-oxidant168 reached to 90.41%,which could be the result of degradation products of antioxidant 168.Commercial antibacterial agents（SRT,ECO,LF,JL）were incorporated into low density polyethylene（LDPE）and high density polyethylene（HDPE）.Antibacterial properties of the sheets were studied by three methods including the filming method,the inhibition zone method,and a method of simulating the real environment.The migration of antibacterial agents from sheets into food simulants was also investigated.It is found that the antibacterial inhibition percentages of LDPE sheets containing LF,JL and 1.5%SRT reached above 90%.Moreover,the inhibition percentage of ECO-containing sheets exceeded 99%,however,it is prohibited in food contact materials since the toxicity of triclosan which is the main bacteriostatic component of ECO.The migration of inorganic elements in the antibacterial sheets into 3%acetic acid did not exceed the specific migration limits（SML）specified in the newly revised EU regulations.