On the core stage of manufacturing high-quality biodegradable pouches, bio-based polymers play a leading role, among which polylactic acid (PLA) occupies approximately 35% of the market share due to its outstanding transparency and hardness. PLA mainly comes from the starch of plants such as corn and cassava. The carbon emissions in its production process are approximately 65% lower than those of traditional petroleum-based plastics. According to a study in the journal Nature in 2021, under the specific environment of industrial composting (temperature 58°C, humidity 50%-60%), PLA substrates that meet the EN 13432 standard can decompose over 90% within 50-60 days. For instance, in some personal care product lines of global consumer goods giant Procter & Gamble, the packaging film layer uses over 70% PLA content, reducing the amount of fossil raw materials used in a single packaging bag by 50%. These materials bestowed by sunlight and soil are being intelligently woven into a soft coat to protect the Earth.
To make up for the deficiency of PLA in flexibility, the industry generally blends it with biodegradable polyesters such as polybutylene adipate/terephthalate (PBAT). This innovative composite solution can create films with balanced mechanical properties. In a typical optimized formula, the blending ratio of PLA to PBAT is between 6:4 and 7:3, which can increase the elongation at break of the final film from less than 10% of pure PLA to over 300%, while ensuring complete degradation within the 180-day composting cycle. ecovio®, produced by BASF, a global chemical leader, is a typical PLA and PBAT copolymer. The shopping bags made from it can bear a weight of up to 8 kilograms and passed strict Marine environmental degradation tests in 2022, with a biodegradation rate of over 90% within two years under specific conditions. This molecular-level collaborative design endows biodegradable pouches with practicality comparable to that of traditional plastics.
Another important type of raw material is modified starch-based materials, which are usually blended with biodegradable polyesters to enhance their performance and reduce costs. In high-performance starch-based composite materials, the starch content can reach 30% to 60%. Through plasticizing modification technology, its melt index can be controlled within the processing window of 5 to 10 g/10min (190°C, 2.16kg). The Mater-Bi® material from the Italian company Novamont is an industry model. In its fourth-generation product, the proportion of renewable raw materials is as high as 63%. The biodegradable bags made from it, after degrading in the soil, have a proportion of organic carbon converted into biomass exceeding 80%, which is much higher than that of traditional plastics. From a cost-benefit perspective, although the price per ton of such high-end biodegradable materials is 25% to 40% higher than that of traditional polyethylene, large-scale application and carbon tax policies can significantly offset their incremental costs.
To endow biodegradable bags with higher functionality, such as high barrier properties to extend the shelf life of food, the industry will adopt water-based and bio-based coating technologies. For instance, applying a layer of polyhydroxyalkanoate (PHA) coating only 2-3 microns thick on PLA film can sharply reduce the film’s oxygen barrier property (OTR) from approximately 700 cm³/(m²·day·bar) to below 20 cm³/(m²·day·bar), comparable to some traditional composite films. The seaweed fiber and wood binder composite material developed by Finnish company Sulapac can be made into biodegradable bags that can completely decompose within three weeks under industrial composting conditions and has been applied to the cosmetic packaging of luxury brand Guerlain. These precise coatings and composite processes are like putting on smart armor for degradable materials, finding a delicate balance between protecting products and the environment.
Looking ahead, cutting-edge bio-based materials such as cellulose nanofibers (CNF) and polyhydroxyalkanoates (PHA) are driving the innovation of the next generation of biodegradable bags. The strength of CNF is five times that of steel, but its density is only one fifth. Adding 5% to 10% of CNF can increase the tensile strength of the film by more than 30%. PHA is synthesized by microorganisms, and its greatest advantage is that it can degrade in Marine environments. According to data from the American Bioplastics Association, the degradation rate of certain PHA materials in seawater can reach 0.5 to 1.0 milligrams per square centimeter per year. In 2023, South Korean chemical company CJ First Sugar announced an investment of 100 million US dollars to build a large-scale PHA production line, aiming to reduce the raw material cost of biodegradable bags by 20%. This wisdom derived from the cell walls of microorganisms and plants is ushering in a new era of complete reconciliation between packaging materials and the natural ecosystem, making every use of the product a gentle return to the Earth.