The core process in preparing coated paper is coating, also known as extrusion coating. Traditional processes use resins such as polyethylene (PE) as the main coating material. However, with increasing environmental protection requirements, the technology of preparing biodegradable coated paper using bio-based or fully biodegradable materials (such as PLA, PHA, and PBAT) has become an important development direction.
Coating is a process in which molten resin material (such as PE) is cast onto a substrate (paper) through an extruder, and then pressed and cooled to form the final product. Its manufacturing process mainly includes preparing the base paper, coating process, drying treatment, and winding or cutting. The coating process uses dip coating or spray coating to evenly coat the liquid coating onto the paper surface. The drying temperature is generally around 100℃, and the time is about 30 minutes. This process requires less adhesive, has less environmental pollution, and meets hygiene standards.
To address the problems of traditional PE coated paper being difficult to degrade and recycle, biodegradable coated paper has become a research hotspot. These materials are manufactured using bio-based or fully biodegradable materials such as PLA, PBAT, and PHA through coating or composite processes. For example, Hengxin Life has achieved mass production of PHA-coated paper products (such as paper cups and lunch boxes), and its products have obtained BPI home composting certification. Regarding patented technologies, Zhejiang Ruiwei New Material Technology Co., Ltd. has disclosed "a biodegradable, fully bio-based coated paper suitable for home composting and its preparation method," whose biodegradable film uses a blend system of PHBV and PBSA. Another method for preparing fully biodegradable coated composite paper involves coating a fully biodegradable adhesive material between the base paper and the fully biodegradable film using a laminating machine, followed by hot pressing and cooling to form a three-layer composite structure with an overall relative biodegradability ≥90%.
