>> Monday, 5 May 2008
Not just about Eastman Chemical Company products but the trade name is perfect for properties of copolyesters. There is one more which I know SK Chemicals (in Poland known from PET installation) and maybe someone else but sorry if I skip it. Some information from chemistry. Amorphous transparent copolyester is produced by the reaction of terephthalic acid (TPA) with ethylene glycol (EG) which a certain amount of EG is replaced with cycloheksane dimethanol (CHDM). The most important factor is the proportion between EG and CHDM. When we increase the CHDM level we prevent crystallization, increase chemical resistant, transparency, and improve processability (lower melt temp., less restricted drying).
For the reason I am involved in polymer field I promote even I do not know about it polymers. The key point is to replace glass, on the other hand to replace polymers such as: PMMA, SAN, etc. in the packaging segment. These materials have some adventures comparing to copolyesters, primo there are cheaper per kg but it is not always the way we should go and it can draw to wrong conclusions.
There are not so many PETG commercial applications but I think there are notable. For those who are more interested please use net sources. When we compare to PMMA it is margin. When you take products from this two materials you will feel the difference not only in your pocket. PETG is heavy has higher density, maybe it will be subjective but it is more like glass this is what you can see, the effect. There will be better impact, chemical resistant, stress cracking, you can eliminate PP insert.
I have been focused just on packaging application and more on cosmetic and injection molded parts. On the other hand believe me even packaging can be technological challenge when we consider parts with wall thickness higher than 10 mm. There is a space for the most important what I wanted add, my own experience. This two suppliers offer grades known as extrusion blow molding and I suggest to take a shot and inject it. What we receive, lower material costs (this grades are much cheaper!) if we can not convince the customer in the other way. It is worth trying.