Processing Blowing Your
Processing Blowing Your Own Reprinted in part with permission of Water Conditioning & Purification Magazine, © September 2006. Any reuse or republication, in part or whole, must be with the written consent of the Publisher. Publicom, Inc., Tucson, Arizona USA www.norlandintl.com Article contributed by Bruce Kucera, Vice President of Norland International Inc., Lincoln, Nebraska, USA PLA Bottles For the time being, PLA as a raw material for bottle applications is suitable rather for niche markets and certain filling goods than for the big CSD (carbonated soft drinks) etc. But even for such niche markets, supplied by small to medium-sized bottling companies on-site manufacturing of PLA or PET bottles has advantages. Why take a do-it-yourself approach? Because it pays! Manufacturing your own bottles on site can yield a dramatic cost-per-bottle savings, primarily by cutting out the shipping costs. Current petroleum pricing negatively impacts transportation costs, of course. In some cases, bottlers can save up to 50 percent on their bottles by making their own, Actual savings varies business by business, based on distance from suppliers, and other considerations. On-site manufacturing also helps alleviate inventory problems. When bottlers make their own, they minimize the required warehouse space. Additionally, they eliminate concerns about the timing of vendor deliveries. Preform purchase and shipping issues, of course, remain the same. Blow molding machines specifically designed for use by the small- to medium-sized bottling companies are now available. No longer are the bigger operations the only ones who can benefit from making their own bottles. 20 bioplastics MAGAZINE [02/07] Vol. 2
Processing PLA Bottle-making The technology of PLA-preform making was described in bioplastics MAGAZINE issue 02/2006. Here, we address the issues involved in designing a blow molder capable of manufacturing bottles from PLA preforms. We also look at the added benefits to the bottlers who use PLA bottles in the business. There is little difference between PLA and PET bottles in terms of appearance and performance. In most cases, what you can do with PET, you can do with PLA, including shape, size, color and other design features. Customers will not know the bottle is made of PLA unless you tell them. The difference is found in material characteristics. Hence, the requirement for PLA-specific blow molders, which must address special issues. Traditional PET blow molders cannot handle PLA successfully. The primary issue is one of material temperature, which includes both preheating of the preforms before entering the stretch-molding process, and subsequent cooling down of blown bottles. PLA preforms must be heated to approximately 75°C before entering the stretch-molding process, as opposed to 100°C for PET. At the higher temperature, PLA starts to shrink, so the typical PET blow molder is problematic with PLA. While PLA preforms heat up easily, the material is difficult to cool down; bottle deformation results when they are not adequately cooled before they exit the molds. Therefore, the freshly blown bottles must be cooled down quickly before they leave their molds. Consequently, special cooling techniques, therefore, must be designed and built into each mold. Additionally, precision process control over all heating lamps and blowing sequences is a must. Fluctuation of a degree or two either way leads to finished bottle quality issues. PLA‘s temperature sensitivity also requires enhanced airflow to ensure even heating in the heat tunnels. When multiple heat tunnels are involved, it is critical to precisely compensate for potentially different heat lamps and airflow so that bottles from each tunnel are consistently heated for optimal performance in the molds. This ensures a consistently high quality finished bottle. Precision control over air pressure and flows are equally critical. This technology helps move PLA material down from the preform‘s neck area to the bottom to make sure desired thickness is achieved in the bottle from bottom to top. Marketing benefits From a marketing perspective, there are several key advantages for bottlers to convert to PLA bottles. The first is product differentiation. Let‘s face it. In the case of bottled water for example, there‘s not much difference between one bottle of water and another. Brand name, methods of water purification, and price are points of differentiation. PLA becomes another point to help bottlers distinguish their product from their competition, particularly those still using PET bottles. The bottled water market often targets a demographic that prides itself in healthy lifestyles. Typically, this also includes environmental concern and a proclivity for "eco-friendly“ products. PLA offers a tangible environmentally friendly argument for its use. There‘s publicity to be gained and media attention to be earned by announcing a switch to PLA and by promoting product as using eco-friendly materials. Following are points about PLA that capture attention of the market, and result in legitimate environmental benefits: 1. The production process of NatureWorks PLA uses 68 percent less fossil fuel resources than traditional PET plastics. NatureWorks has found that producing 1,000 bottles from PLA resin requires 33 percent less fossil fuel resources and emits 42 percent less greenhouse gases than making 1,000 bottles from PET. (LCA Consultants Report). 2. PLA is the world‘s first greenhouse-gasneutral polymer. Bottlers considering switching from PET preforms to PLA must be aware that preform selection and bottle design are critical to producing high-quality bottles. Make sure your blowmolding machine supplier approves your perform supplier and bottle design for optimal performance. bioplastics MAGAZINE [02/07] Vol. 2 21
