One of the paths of green development of plastic packaging: Use high-performance materials to break through technical bottlenecks
Among many packaging materials, plastic packaging accounts for the highest proportion. It is worth noting that abandoned plastic packaging will weather and decompose into fine particles, which may eventually enter the human body through various forms. But plastic packaging is essential for goods, in the case that it can not be replaced, how to eliminate its harm? This paper proposes a third approach: the use of high-performance materials.
There are two major difficulties in the large-scale use of high-performance material packaging.
First, the price is generally high. The use of high-performance materials to replace ordinary plastics is more conducive to environmental protection. For example, the use of water-based ink for packaging printing, reducing the cost of post-packaging cleaning and sewage treatment. The use of FFS (molding, charging, heat sealing) heavy wrap instead of brushed woven bags is conducive to reducing particle pollution after plastic breakage, and FFS heavy wrap is also gradually thinning. The use of PETG (polyethylene terephthalate -1, 4-cyclohexane dimethyl ester) to replace the halogenated PVC (polyvinyl chloride) packaging is conducive to physical and chemical recovery. PETG thermal shrink film is a high-performance shrink film, with a final shrinkage rate of more than 80%, can be made into the packaging of complex shape containers, with high blister force, high transparency, high gloss, low fog, easy to print, not easy to fall off, low natural shrinkage rate during storage advantages, used in beverage bottles, food and cosmetics shrink packaging and electronic products such as shrink labels.
In 2022, the demand for PETG in China will exceed 100,000 tons, mainly replacing PVC for beverage labels. EVOH (ethylene-vinyl alcohol copolymer) was used as high barrier packaging material. EVOH is a non-toxic and environmentally friendly material, which will not produce toxic and harmful substances in the specific processing link, and is one of the high barrier performance materials supported by China's policy. EVOH has excellent barrier property, and its barrier property to oxygen is 10000 times that of PP (polypropylene) and PE (polyethylene). Good oil resistance, suitable for packaging oily liquids, toxic and volatile products, such as industrial solvents, pesticides, pesticides, etc. Good transparency and gloss, can be used as high-quality transparent packaging, to ensure the appearance of packaged products; It has good chemical resistance and strong antistatic properties, easy to process, can be extruded and co-extruded by traditional polyolefin processing equipment, and is widely used in composite film intermediate barrier layer, applied to dairy products, meat, juice cans and condiments packaging in the food industry, as well as solvents, chemicals, air conditioning structural parts, gasoline drum lining, electronic component packaging and so on.
Second, China's production of high-performance packaging materials technology level is low. Taking COC (cycloolefin copolymer) and COP (Epoxy-polypropylene copolymer) as an example, COC/COP is a new type of amorphous thermoplastic engineering plastics made of copolymerization of olefin and cycloolefin or cycloolefin monomer. It has high transparency, low birefringence, low hygroscopicity, low shrinkage and low dielectric constant. And a series of excellent properties such as good heat resistance, chemical resistance, light resistance, etc., are widely used in packaging, optics and medical fields. The production process of COC/COP is complex, and the synthesis of cycloolefin monomer is difficult. At present, only the technology and production process of Japan Rayon Company, Japan Baoli Plastics, Japan Synthetic rubber and Japan Mitsui Chemical enterprises can achieve large-scale production in the world.
At present, the global COC/COP production capacity is about 83,000 tons/year, and Japan is the main supplier of COC/COP. In 2021, China's consumption of COC/COP is about 21,000 tons, which is the main consumer market of COC/COP in the world, mainly used in optical, packaging and medical fields. Japan, Europe and the United States have appeared COC/COP materials instead of borosilicate glass bottles as pre-pot-sealing packaging materials. The annual demand for COC/COP in China's medical packaging field is about 5,000 tons. Due to the technical monopoly of the product, the whole industrial chain from raw material monomer norbornene to catalyst has not been fully industrialized, and most of the COC/COP products in our market come from imports. It is expected that by 2025, China's annual consumption of COC/COP will increase to 29,000 tons.
In addition, EAA (ethylene-acrylic acid copolymer) can effectively bond metals and plastics, paper and plastics and other substances, durability, transparency, excellent bonding, widely used in food and drugs and other flexible packaging fields. EAA can also be used to make electric vehicle battery electrodes and diaphragms, which can improve battery stability; Improved sealing and durability when used in photovoltaics. EAA can also be used for vacuum packaging of meat, etc., to extend the storage time of food. Domestic enterprises have not yet mastered EAA independent production technology, EAA all rely on imports, annual imports of 20,000 to 30,000 tons. In June 2023, the Sino-Korean Kerui EAA project jointly built by Satellite Petrochemical and SK Zhixin started construction in Lianyungang, which will ease the import pressure of this product in China after completion.
Although the green development of plastic packaging in China is facing various difficulties, but China's determination to protect the environment has never wavered, and these difficulties are precisely the direction of our improvement, I believe that China will overcome various difficulties, seize the development opportunity, and walk out of a green development path of plastic packaging.
