Creating white BOPET films using voiding agents is a well-established process, with barium sulphate being one of the most commonly used raw materials. While calcium carbonate is often used to achieve the same effect in biaxially oriented polypropylene (BOPP) film applications, technical challenges have prevented its widespread use in more demanding resins until now.
Groundbreaking work by Sukano's R&D team and one of its core suppliers has overcome these difficulties, allowing calcium carbonate to potentially become the future go-to voiding agent for biaxially oriented films produced in speciality resins such as PET and PLA. A shift from barium sulphate to selected grades of calcium carbonates with Sukano's masterbatch technology could provide a number of benefits to manufacturers.
First, calcium carbonate can improve opacity during film orientation and stretching, and its enhanced whiteness can achieve similar, or even lower, quantities of filler to achieve the same film opacity level.
BOPET and biaxially oriented polylactic acid films that are voided with calcium carbonate present a less glossy surface than white films produced using titanium dioxide, creating a paper-like effect. Calcium carbonate can also lower the film density in comparison with voided barium sulphate or pigmented titanium dioxide films, helping to improve yields and reduce the total weight, thus enhancing a film's commercial value.
Sukano's expertise extends beyond research and development. In order to minimise issues common to early-stage project development, Sukano can also evaluate performance at a lab scale using its in-house COEX film line dedicated to PET, and validate the optical physical properties using a KARO IV labstretcher.
This enables customers to select the most promising product performance before going to pilot or industrial line trials. Sukano's experts can also help preselect the most suitable calcium carbonate grades, according to process and end-application requirements, as well as providing tailor-made masterbatch formulations.