The Institute of Biodegradable Materials reported that the packaging industry has now become a major source of "white pollution", especially the waste accumulated throughout the year in the express delivery industry has caused a great burden on the planet. Therefore, the packaging industry has vigorously advocated the 3R1D principles of packaging Reduction, Reuse, Recycle, and Degradable in recent years, and encourages the development of degradable packaging materials.
Background:
The "Opinions on Further Strengthening the Control of Plastic Pollution" issued by the National Development and Reform Commission on January 19, 2020 clearly stated that by the end of 2022, the use of postal express outlets in Beijing, Shanghai, Jiangsu, Zhejiang, Fujian, Guangdong and other provinces and cities shall be prohibited in advance. Degradable plastic packaging bags, disposable plastic woven bags, etc., reduce the use of non-degradable plastic tape. By the end of 2025, non-degradable plastic packaging bags, plastic tapes, disposable plastic woven bags, etc. will be banned at postal express outlets nationwide.
Compared with the traditional packaging material PE and PP, PLA (polylactic acid) has high transparency, good processability, and good printability. It has advantages when used as packaging materials. It can be made into films, foam materials and containers, such as flexible packaging bags and plastics. Bottles, cushioning materials, disposable tableware, etc.
PLA film
PLA film mainly includes high transparent film, heat shrinkable film, pellet blend blown film bag and PLA-based composite film.
PLA film can replace traditional film materials as a new packaging material. For example, Wal-Mart supermarket requires the use of fully degradable PLA film bags to replace traditional non-degradable PE bags. Japanese electronic products have also begun to use PLA nano-composite film packaging.
PLA container
Due to the degradability of PLA, PLA containers are mostly used in short-term shelf food packaging.
The transparency and oxygen barrier of PLA bottles are better than PE bottles. NatureWorks uses PLA bottles to package organic juice drinks, which can guarantee a 60-day shelf life. The Danish Faerch Plastics Company uses PLA to package low-temperature pasta, meat, salads and other fresh foods, which can achieve a long shelf life. The European market has launched PLA-made yogurt cups and beverage packaging bottles, which can meet EU standards for food containers.
The highly transparent and heat-resistant PLA water bottles and PLA baby bottles developed by Hangzhou Xusheng Technology Co., Ltd. can meet the application conditions that are both transparent and heat-resistant (water bottles and baby bottles require heat-resistant temperature ≥100°C). The domestic market also coats PLA on paper to make coated paper cups, which are used in various water- and oil-proof food packaging.
PLA foam material
PLA foaming material is also biodegradable and can be used to produce disposable catering utensils (such as fast food boxes, instant noodle bowls, etc.) and cushion packaging without white pollution. For example, the "Graft" series of disposable tableware is designed with PLA foam material to have a realistic shape of fruits and vegetables, which is environmentally friendly and beautiful.
Compared with traditional PE and PP materials, PLA has a higher melting point (about 180°C) and better processability. The hardness and mechanical properties of PLA are similar to those of traditional resins, and it has good transparency and excellent gloss. It is especially suitable for packaging materials.
Disadvantages:
However, compared with high-barrier nylon, polyvinylidene chloride, etc., PLA has poor oxygen and water vapor barrier properties, insufficient protection for oily foods, and PLA has poor toughness, low heat distortion temperature, and poor impact resistance. It is often unable to meet the requirements of circulation in harsh environments. In addition, the degradation cycle of PLA is not well controlled. Compared with traditional resins, the price is slightly higher (about 30,000 yuan/ton). At this stage, it is not advantageous for packaging.
Although PLA has shortcomings such as relatively brittle texture, poor heat resistance, and poor barrier properties, these shortcomings can be corrected by modification such as copolymerization, blending, and plasticization. In recent years, scholars at home and abroad have been actively studying the polymerization process and modification technology of PLA, and have developed a variety of green packaging materials using PLA as raw materials.
