PETpla.net Insider 07+08 / 2016

CAPPING / CLOSURES 35 PET planet insider Vol. 17 Please order your copy at the PETplanet insider book shop: https://www.petpla.net/books Bottles, Preforms and Closures - A Design Guide for PET Packaging Second Edition by Ottmar Brandau € 115,00 180 pages © Copyright Elsevier 2012 * This article was published in Bottles, Preforms and Closures, Ottmar Brandau, Chapter 4.4 Copyright Elsevier 2012 You make a great product – why hide it? We’ve seen the future of canning and it’s Klear. Milacron’s Klear Can technology gives manufacturers a cutting-edge, cost-competitive alternative to metal cans for fruits, vegetables, soups, meats and other products – and it’s transparent, so you can show off your goods. Using the same machinery as metal cans, going Klear requires minimal investment. With the option to use colored plastic cans, in-mold labels, or standard labels, the possibilities are endless. Ready to see what you can do? Contact us or visit www.Milacron.com to learn more. 4.5 Resins There are mainly two resins used for closure production: PP and high-HDPE. Liners for oxygen-sensitive products contain other components (see chapter 4.3). In some applications either mate- rial may be used but others are suitable for just one. There is little price differ- ence between the two. It is therefore important to understand the differ- ences between these two materials for those applications where a choice exists. Both materials belong to the group of plastics known as polyolefins. They are thermoplastics, which means that they deform with the application of heat. Both materials consist of long chains of carbon and hydrogen atoms. To obtain good flow in the IM process, the weight distribution, i.e., the difference between the shortest and longest chains, is kept narrow. Both materi- als form a crystalline struc- ture that must be completely melted by frictional heat in the extruder. 4.5.1 Polypropylene PP is the most widely used thermoplastic with excellent availability in every part of the world (Fig. 4.30 and 4.31). Figure 4.30 PP structure as monomer (on the top) and polymer Figure 4.31 The PP molecule