Injection Molding: Lubricant Coating Keeps PET Preforms Scratch-Free

Prevent scratching of PET preforms during bulk packaging and handling with a new system for spraying a lubricant coating on the preforms. The Preform Coating System (PCS) was developed by Bonino Group in Italy in collaboration with the Chem-Trend in Germany, the coating manufacturer, and Steidle GmbH, a German specialist in micro-spraying lubrication systems.

The coating is Chem-Trend’s Lusin Lub O 32 F, originally developed to be sprayed onto stretch-blown PET bottles to keep them from sticking together and blocking conveying lines. In the new preform application, the coating not only prevents scratches, Chem-Trend claims, but also increases the number of preforms that can be filled into a bulk box, gaylord or octabin by reducing friction and sticking between the preforms. The multipurpose coating is said to be food-contact compliant and also acts as a release agent that improves bottle demolding and definition during the demolding process—without affecting the working life of the heat lamps. It also eliminates bottle jamming in downstream conveying lines.

Bonino Group developed a self-contained, portable spraying cabinet that can easily be integrated into production lines. It is installed directly after the injection machine and before the soft-drop or bulk container. Spray is applied only to the body of the preform, not on the thread. A special “Safeguard” provision around the neck of the preform prevents the coating agent from entering the preform. The unit is said to accommodate virtually all preform sizes and shapes with only a few minutes’ adjustment. The integrated PIC coating system from Steidle accurately doses micro quantities of the coating and ensures that the entire bod of each preform is coated.

Lusin Lub O 32 F and the Bonino PCS system are both available in the U.S. through Chem-Trend.