The use of biocides in plastics is commonplace. They are added to protect the plastic from degradation by microbes or to provide an external antimicrobial hygienic surface.
Biocides are selected on the basis of their function and the application for which they are intended, but choosing the right biocide is often not so simple. As well as biocidal performance, the in-process stability, migration, leachability, light and heat stability may all be important factors.
This Rapra Review Report examines the use of biocides in plastics with reference to material types and application requirements. The commonly available biocides are reviewed and details of their strengths and weaknesses are provided. The author reviews the frequently used test methods for fungi and bacteria, and, in an ever-changing regulatory environment, explores the influence of legislation on the current and future use of such biocides.
This report will be of interest to biocide suppliers and plastic product manufacturers, and to all professionals requiring information on biocide chemistry and application.
This detailed and state-of-the-art review is supported by an indexed section containing several hundred key references and abstracts selected from the Polymer Library.
2 THE NEED FOR BIOCIDES IN PLASTICS AND BASIC MICROBIOLOGY
3 PLASTIC MATERIALS REQUIRING BIOCIDES
3.1 Biostabiliser Effects
3.1.1 Nutrient Sources for Fungi and Bacteria
3.1.2 Microbiological Effects
3.1.3 Organisms of Importance
3.2 Hygienic Applications
3.2.1 Organisms of Interest
3.2.2 Merits of Such Biocides
3.2.3 The Bacterial Problem
3.2.4 False Claims
3.2.5 Conclusions Regarding Hygienic Applications
3.3 Active Packaging
4 TEST METHODS
4.1 Fungal Test Methods
4.1.1 Fungicidal Procedures
4.1.2 Fungistatic Procedures
4.1.3 Soil Burial
4.1.4 Humidity Chamber or Vermiculite Bed
4.2 Bacterial Test Methods
4.2.1 Resistance of Plastic to Bacteria
4.2.2 Antimicrobial Plastic
4.2.3 Pink Stain Test
4.3 Laboratory Tests versus use Conditions
5 AVAILABLE ACTIVE INGREDIENTS
5.1 Migratory Biocides
5.1.3 Butyl BIT
5.1.4 Zinc Pyrithione
5.1.5 Iodo-Propylbutyl Carbamate (IPBC)
5.1.6 N-Haloalkylthio Compounds
5.1.7 Carbendazim (N-benzimidazol-2-ylcarbamic acid methylester)
5.1.8 Bethoxazin (3-Benzo(b)thien-2-yl-5,6-dihydro-1,4,2-oxathiazine 4-oxide)
5.2 Non or Low Migratory Biocides
5.2.1 Triclosan (2,2,4-dicholoro-2-hydroxydiphenyl ether)
5.2.4 Sustainable Antimicrobial Polymers (Degussa)
5.2.5 Titanium Dioxide Nanoparticles
5.3 Other Ingredients
6 LEGISLATION REGARDING BIOCIDES
6.1 Limitations of Use
6.2 Future Requirements
6.3 BPD Exemptions
Dean Nichols has a BSc. (Hons.) degree in biology and has worked for THOR, a speciality chemicals company and leading biocide company, for the past 15 years. His experience has involved research and development and marketing of biocides and other speciality chemicals to the Middle East, Europe and some countries in the Far East. Currently, he is a member of Thors biocide product management team and has a global role for promotion of products, services and expertise into various market sectors.