PETpla.net Insider 06 / 2015

CAPPING CLOSURES 31 PET planet insider Vol. 16 No. 06/15 www.petpla.net shows how delicate and professional closure production still is.  1885 – Already 150 patents applied in the USA for closures and lids  1892 – William Painter invented crown cork  1900 – Ceramic stoppers with rubber washer  1940 – Aluminum roll-on  1970 – Albert Obrist introduced the first prethreaded plastic closures  1985 – Albert Obrist became part of Crown Cork and Seal Company  1985 – HC Industries, today Alcoa, introduced the first compression- moulded closures  2005 – More than 90% of all clo- sures are produced in plastic 4.1.2 Closure Functions Closures are often overlooked when we discuss about bottle pack- ages. However, they form an impor- tant part of the overall functionality. In this chapter we are discussing all the important details of closure design, process and tool selection, and opera- tional considerations. Most plastic caps are threaded, allowing consumers to easily open the package without the use of tools (such as a bottle opener for crown corks), and then reseal it to finish the prod- uct at their convenience. This easy resealing is maybe the biggest advan- tage that threaded caps have over other forms of closures. Other pack- ages have incorporated this feature often at considerable cost. Examples are necks with caps fastened to carto- nated drinks and rotating crown corks that can be opened without a tool. The main function of the cap is of course to prevent leakage of the prod- uct from the bottle and to protect it from contamination, and it must do so under all conditions that the package was designed for. Caps for carbon- ated beverages, for example, must withstand significant internal pressure, whereas caps for contents that could suffer from microbial contamination must be sterilised before or after fill- ing. But most modern caps also have tamper evident bands that assure customers that the seal has not been broken since the bottle was filled. These are designed to either stay on the cap in the unscrewed position or stay on the bottle instead. Caps may also provide proof of purchase or inform the consumer of an instant win. They may be printed or may carry the logo or some other identification of the brand owner. Besides protecting the contents, caps also must be consumer friendly in terms of unscrewing and reseal- ing. Other caps must be designed for the opposite function, i.e., prevent children from getting access to the contents of the bottle. Child resistant closures are not part of the beverage industry but may be used for medica- tion and similar products. Another group of closures are sports caps. These closures feature a lower member that is in firm contact with the bottle, usually by means of a thread, and an upper member that features some way to open access to the drink in the bottle. These are pop- ular with sports enthusiasts because they allow drinking by using one hand only, a nice feature for consumers involved in some activity. Caps may be produced in IM or CM in 1 or up to 192 cavities. Chap- ter 4.6 provides an overview of both methods and compares the important elements. There is also a significant differ- ence in tooling design. Tamper evi- dent bands may be formed right in the tool or slit as a secondary operation. Some tools use unthreading devices to strip closures off the injection cores where others “bump” them off. Low- cost tools save initial capital outlay but may run at slower cycles, produce inferior quality, and have higher main- tenance costs associated with them. It can be seen from the above con- siderations that a variety of closure designs is necessary to fulfill the vari- ous requirements. It should also be obvious that closure as well as tooling design play an important role in the design of the overall package. 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 3.8. Copyright Elsevier 2012 Figure 4.1 Raw material is by far the most important cost component. (Graph courtesy of Corvaglia Ltd).