PETpla.net Insider 10 / 2019

TOP TALK PET planet Insider Vol. 18 No. 0/17 www.petpla.net 10 and put them into reality. However, with greater experience, my global network and my innovative efforts, I was encouraged to take action and so I founded ReduPET GmbH. PETplanet: Have you achieved your ambitious objectives from that time? Stefan Bock: My activities were divided into two focal points. I started by writing down all of my experiences in a logical and practical way so that I could work out practicable solu- tions for conserving resources. These were documented and translated into several languages. I then presented these to the PET processor industry as a package, whereby their opera- tional employees could do a workshop and together work out the potential new measures that they could adopt in their production facilities. I would be on hand as a consultant throughout implementation so that these projects did not grind to a halt. This works well in the processing industry because it is realistic, understandable for all participants and the measures always lead to a noticeable success. My cus- tomers and I are very happy with this development. I brought to market maturity the material saving innovations Mint-Tec and Neck-Lite in partnership with company CPS (Creative Packaging Solution) as holder of the patents. Even when we have experienced enormous support, as experienced with the blow moulding machine manufacturers, the market reaction is very varied. Drinks manufactur- ers in particular, who are among world market leaders, are especially taken with the technologies. Some have already issued market releases for their products. The technologies Mint-Tec and Neck-Lite are revolu- tionary and provide a bridge between established injection moulding and blow moulding – therefore calling into question the previous interaction of these technologies. And this is all kept relatively far away from the end customer. There are some hurdles to overcome as acceptance is not easy to obtain and each individual wants to benefit from a technology like this. Without profit, interest is usually almost nothing. This is why CPS has been working on this development for over seven years and has brought in enormous resources in terms of finance and time. ReduPET GmbH is doing this in the same style to guar- antee longevity. Of course, motivation comes from our successes. Today, we are very proud that Mint-Tec is now running industrially. PETplanet: With ReduPET GmbH, you are trying, for example in the product process for preforms, to save up to 8% of material consumption and costs; at the base of the bottle it is up to almost 20%. What kind of technol- ogy is behind this? What are Mint-Tec and Neck-Lite all about? Stefan Bock: Mint-Tec and Neck-Lite are two material-saving innovations for PET bottles. In the manufacturing of a PET bottle, two processes usually come into play – injection moulding and stretch-blow- ing. However, the two processes do not fit optimally together, as each is subject to the laws of physics. In the injection moulding process, the pre- form is manufactured. This preform is then reheated in a further process and stretch blown into the finished bottle, where the plastic undergoes high-grade hardening. To achieve optimum hardening, the preform would have to demonstrate a geom- etry which cannot be manufactured purely through injection moulding technology. For example, the preform base would have to demonstrate a much lower wall strength to enable the optimal stretch blowing of the subsequent bottle base. But this is not possible with injection moulding. With thin walls, the material would freeze too quickly and the unavoid- able shrinking process caused by cooling, primarily in the seal area, could no longer be compensated. This would result in leaky bottles. By contrast, the blowing machine is not really capable of stretching out the material accumulation in the base to a satisfactory level. So the material remains unnecessarily in the base area of the bottle – a not inconsider- able waste. If you cut the bases off PET bottles in the supermarket, this waste can more or less be observed on almost all bottles. It must also be noted that the blowing process benefits a great deal from the light base. It enables a blowing machine to produce products more quickly with lower energy consumption in the heater oven. The shorter cooling time in the base enables a faster produc- tion run. The blowing pressure can also be reduced, as the base can now be formed more gently, which means another significant energy saving. The same idea is the basis of the Neck-Lite innovation. In the neck area, beneath the transport ring, the melt channel is shaped in a way that is just as unnecessarily thickened, so that the PET material does not freeze too quickly and the shrinkage, again caused by the cooling process, can also be counteracted. The idea here is to leave only small channels to supply the compensating material at the neck during the shrinking process, while the rest of the material can be omit- ted. This leads not only to a material saving but also the blowing process requires significantly less energy Neck-Lite left: Here you can see that the amount of material under the transport ring has been greatly reduced com- pared to the standard product (on the right). Left: Cross section through a Mint-Tec preform with reduced bottom wall thick- ness in comparison to the standard (on the right).