Bottle Applications Caps
Bottle Applications Caps & Closures from bio resources KISICO Verpackungstechnik GmbH of Oestrich-Winkel in Germany has been observing the development of the bioplastics market for many years. At an early date they began developing caps made from different bioplastics. Over the course of the last few years the range of suitable raw materials based on biopolymers has increased significantly, for both biobased and biodegradable plastics. The largest percentage of the bioplastics that Kisico uses are made from renewable raw materials and are biodegradable. In most applications however, it is impossible to achieve the compostability according to ISO 14851 or 13432 for caps and closures because the required wall-thickness is too big. This means that the time taken for composting is too long, even if the bioplastic is completely biodegradable (it just takes longer). Depending on the application and on customer requirements the most suitable material has to be selected from a wide range of already approved materials. Plastics made on the basis of wood and lignin have the visual appearance of something natural. The same applies to materials with visible, natural fillers. These fillers can be waste material from agricultural food production, such as wheat bran or corn samp these plastic materials are not biodegradable because of the basic material used. Often the rheological and mechanical properties are not ideal. Thus a deep knowledge of the raw materials is crucial during the development and design of new caps. If the filler has a high fibre content, or other coarsely ground particles, the properties of the raw materials have to be taken into consideration. Raw materials based on cornstarch or polylactide have the widest range of properties. They can be designed and produced to be very smooth but can also be brittle and hard. This is achieved using different blends and composites. In most cases they are made from renewable materials which are also compostable. They can in fact be completely made of waste from the food and the animal feed industries. As a consequence no additional agricultural land has to be used for production of the raw material. 32 bioplastics MAGAZINE [04/12] Vol. 7
Bottle Applications A lot of caps from the standard Kisico range can be made from these materials. Small threads starting at10 mm up to large threads of more than 70 mm can be realized. Both onepiece and two-piece tamper-evident caps are produced from these materials. A typical example is a two-piece tamperevident cap with a PP28 thread. The caps can be coloured in almost every Pantone or RAL colour. For many years cellulose has been used as basic material for cellulose acetate (CA) and other cellulose derivatives. Today the cellulose used often derives from sustainable forestry. The cellulose based caps made by Kisico can be transparent or both translucent and opaque coloured. Even so, they have a very shiny surface and so are particularly suitably for cosmetic applications. During the colouring of caps made from bioplastics it is important to ensure that the colour is made from natural pigments and does not have a negative impact on compostability. The colour components must not be toxic for microorganisms. This applies especially to copper ions, which are often used for green and blue colours and can create problems. The product range from Kisico also includes hinged caps made of bioplastics. To find suitable biopl;astic materials made of bioplastics it is necessary to carry out a great deal of experimental work and testing. The requirements for the mechanical properties within the hinge are high and must be the same as provided by mineral oil based materials. Even after repeated opening and closing of the hinge it should not break and the cap has to seal correctly throughout the product life. Kisico’s experience also enables the company to offer complete packaging solutions. This includes blow-moulded containers, such as bottles, which are developed and produced together with our partners. www.kisico.de Bio meets plastics. The specialists in plastic recycling systems. An outstanding technology for recycling both bioplastics and conventional polymers bioplastics MAGAZINE [04/12] Vol. 7 33
