Introduction of Promix PET mixing nozzle

During the production of PET preforms, the molecule acetaldehyde (AA) is formed as a by-product of PET. AA can also be found in nature, e.g. in citrus fruits. The very intense taste can be detected even in very low concentrations, especially in water. This is why an excessively high AA content in PET preforms is undesirable. In addition to the recipe, the main influencing factors for the formation of AA when processing PET are the residence time and the processing temperature. Since the residence time in the laminar PET melt flow is uneven, local AA concentrations occur in individual cavities of the mold. This means that in one injection cycle, within a large number of high quality preforms, some with too high AA concentration may occur. This can be counteracted conservatively by using AA blockers. The problem is that AA blockers also migrate into food and therefore, corresponding legal limits must be observed. Moreover, AA blockers represent a considerable additional cost factor.

By using the Promix PET mixing nozzle specially developed for this application, local AA concentrations are evenly distributed in the melt flow. This prevents individual outliers. Since the peaks are reduced by an average of 20 to 30 %, all cavities are then below the permissible AA limit. If AA blockers are used, their effect is optimised thanks to the better distribution in the melt. This leads to significant savings in AA blockers. Not infrequently, it is even possible to eliminate AA blockers entirely, which permanently lowers production costs.