PS Waste to Resin: Tech Path
Polystyrene (PS) is widely used in food packaging because of its light weight, heat insulation, easy molding and low cost. From takeaway boxes, coffee cups to fresh food trays, the global annual consumption reaches millions of tons.
However, the "disposable" nature of traditional PS packaging has caused serious environmental problems: its chemical structure is stable, and it takes hundreds of years for natural degradation.
A large amount of PS waste is accumulated in landfills or flows into the ocean, forming white pollution. According to EU data, the recycling rate of PS packaging waste in Europe in 2020 was only 32%, and the rest was mostly incinerated or landfilled, which not only wastes resources but also releases harmful gases.
However, with the breakthrough of environmental protection technology, the "infinite recyclability" of PS is rewriting this situation. Unlike traditional mechanical recycling (which can only be downgraded and impurities accumulate to affect performance), modern depolymerization and purification technology can restore PS waste to original resin, realize the closed-loop circulation of materials, and completely subvert the linear economic model of "use and discard".
The road to rebirth from waste to food-grade resin
1. Depolymerization technology: breaking the chemical code of molecular chains
The core of PS recycling lies in "depolymerization" - decomposing high molecular weight polystyrene into low molecular weight monomers or oligomers. The current mainstream technologies include:
Pyrolysis technology: In an inert gas environment, PS waste is heated to 300-500℃ and decomposed into styrene monomers through high-temperature cracking.
For example, the pyrolysis process developed by the Swedish company Plastc Energy can convert PS packaging into styrene with a purity of 99.9%, reducing energy consumption by 40% compared with traditional petrochemical production.
Catalytic depolymerization: With the help of catalysts (such as zeolites and metal-organic frameworks), the activation energy of the reaction is reduced and PS decomposition is achieved at a lower temperature. The catalytic technology launched by Sekisui Chemical in Japan can depolymerize PS below 200℃, and the product can be directly used as food packaging raw materials after purification.
Solvent depolymerization: PS is dissolved in a specific solvent (such as toluene and ethyl acetate) and styrene monomers are separated by distillation. This method has low energy consumption and low pollution. The American company Loop Industries uses this technology to build a large-scale recycling plant, which processes more than 100,000 tons of PS waste annually.
2. Purification technology: the core barrier of food safety
The depolymerized styrene monomer needs to be purified at multiple levels to remove residual pigments, additives and trace pollutants to ensure that it meets the standards for food contact materials. Typical processes include:
Adsorption purification: adsorption of organic impurities by activated carbon and molecular sieves.
Distillation purification: separation of low-boiling impurities using a distillation tower, with a purity of up to 99.99%;
Testing and certification: follow the standards of the FDA (U.S. Food and Drug Administration) and EFSA (European Food Safety Authority), and strictly test indicators such as heavy metals and monomer residues.
For example, the recycled PS resin of BASF in Germany has a styrene monomer residue of less than 0.1ppm, which fully complies with the EU Food Contact Materials Regulation (EC) No 10/2011.
Environmental benefits: a leap from resource waste to low-carbon circulation
Sharp reduction in energy consumption: Compared with the traditional process of extracting styrene from petroleum, the depolymerization-polymerization process of recycled PS consumes 50%-70% less energy.
Taking the production of 1 ton of PS resin as an example, the traditional process consumes about 1.8 tons of oil, while the recycling process only requires 0.3 tons of PS waste, while reducing carbon dioxide emissions by 60%.
Sharp drop in landfill volume: If the global PS food packaging recycling rate is increased to 80%, more than 5 million tons of waste can be reduced from entering landfills each year. According to data from the US Environmental Protection Agency (EPA), in 2023, fast food companies that use recycled PS will have a 72% drop in packaging waste landfill compared to 2018.
Carbon footprint optimization: A Swiss Life Cycle Assessment (LCA) study shows that a coffee cup made of 100% recycled PS has a carbon footprint of only 1/3 of that of virgin PS. If combined with a recycling plant powered by renewable energy, the carbon footprint can be further reduced to 1/5.
Our platform connects hundreds of verified Chinese chemical suppliers with buyers worldwide, promoting transparent transactions, better business opportunities, and high-value partnerships. Whether you are looking for bulk commodities, specialty chemicals, or customized procurement services, TDD-Global is trustworthy to be your fist choice.
