Due to their good elastic properties and ease of processing, TPEs are ideal for high-contrast two-component injection moulding applications in hard/soft combination with other thermoplastics.
Manufacturers of consumer products are striving to use their packaging to provide unique selling propositions. At the same time, the increase in shipments of single liquid products as a result of e-commerce, as opposed to conventional large-scale distribution on pallets, increases the requirements for packaging with a reliable seal.
Kraiburg TPE
Intelligent and functional packaging
"A classic soft-touch surface that conveys a high-quality product character to the consumer is no longer enough," said Josef Neuer, Product Management EMEA, KRAIBURG TPE. "That is why we insist on market- and customer-oriented formulations in the development of our materials that pave the way for innovative packaging solutions."
An innovative application for TPEs is the use of dosing valves. MENSHEN of Finnentrop in the Sauerland region, a worldwide leading manufacturer of high-quality closures, developed the one2serve dosing valve, which opens only when pressure is applied to the bottle or tube. As soon as the pressure decreases, the opening slots seal again.
The dosing valve is manufactured as a one-piece finished product using the two-component injection moulding process. The outstanding adhesion of the TPE to the hard component ensures a cost-effective and reliable manufacturing process
Custom engineered compounds
The TPE formulations for use as dosing valves feature elasticity throughout the entire life cycle that is comparable to typical silicones. The hysteresis or elastic-plastic deformation behaviour of these compounds shows a significant decrease in deformation compared to standard TPEs, in which the stress and relief curves are further apart. To ensure that higher dosing pressure is not needed when the valve is opened for the first time, the TPE materials are also specially designed to prevent clogging.
Compatibility with foodstuffs
The new THERMOLAST K materials fulfil the stringent requirements of the Code of Federal Regulations, the US Food and Drug Administration and of the EU Directive for plastic materials that are intended for contact with foods.
The EU Directive contains an extensive positive list of monomers and additives. It applies to materials and objects made of plastic that are intended for use in contact with foods and defines an overall migration limit (OML) of 10 mg/dm². The migration test is conducted for different foodstuff classes by means of food simulants. In general, compliance with the limits is more difficult in applications with a high surface/volume ratio. However, each single application must be analysed on an individual basis. KRAIBURG TPE provides in-depth customer support in this respect.
The KRAIBURG TPE portfolio includes numerous compounds for fatty food applications for which the formulation can be adapted to the specific surface/volume ratio.
Outstanding resiliency
Packaging in the growing e‑commerce sector benefits from the cost-effective two-component injection moulding process.
"The increase in single shipments by post or parcel service necessitates packaging solutions with very good sealing properties," Neuer explained. "For these applications we have developed special materials that ensure an optimal and permanent seal."
KRAIBURG TPE's tests confirm that seals made of these materials retain their outstanding resiliency even after the repeated application of pressure over a period of several weeks.
The specially-developed series for these applications are easy-flowing, which allows even filling of cavities in the injection mould and prevents problems with weld lines. The specific formulation can be adjusted to individual requirements. Due to their good cold elasticity the materials also retain their sealing function during transport and storage at low temperatures.
New applications from the THERMOLAST K portfolio illustrate the diversity of this TPE for increased functionality and performance in view of new trends and challenges in the packaging market.