What is EAA? What are the main processes? ? ?

Compared to polyethylene, the EAA vinyl monomer chain incorporates acrylate monomers; the molecular motion in its amorphous region is influenced by both the crystalline region formed by the vinyl chains and the hydrogen bond interactions between the carboxyl groups. This disrupts the original crystalline structure, increases the distance between molecular chains, and enhances its softness and elasticity. Compared to non-polar polyolefin homopolymers, introducing polar functional groups into the polyolefin chains can significantly improve properties such as the dyeability, adhesion, and compatibility of the polyolefin materials. Compared to ethylene-vinyl acetate (EVA), ethylene-acrylic acid and ester copolymers possess higher thermal stability as well as a wider range of processable conditions, and are widely used in fields such as adhesives, packaging materials, high-voltage cable materials, and blended modified materials.

Research on the production process of EAA began in the 1950s, with researchers focusing primarily on the copolymerization reaction of ethylene and vinyl acetate (VA). By introducing vinyl acetate monomer, researchers found that it was possible to significantly improve the polarity, flexibility, and heat-sealing properties of ethylene copolymers. This discovery laid the foundation for the industrial production of EAA. In 1961, Dow Chemical Company in the United States, in collaboration with UCC (United Carbon Carbide) of the same country, achieved the industrial production of EAA for the first time, producing EAA resin using the high-pressure bulk method. The content of acrylic monomer (AA) has a significant impact on the properties of EAA; it is usually in the range of 2–20%. As the AA content increases, its transparency, toughness, adhesiveness, and resistance to environmental stress cracking improve, whereas its rigidity, moisture vapor transmission, creep resistance, and chemical resistance decrease accordingly. Therefore, precisely controlling the AA content during the preparation process is key to obtaining the desired properties of EAA. Currently, the main production methods for EAA are free-radical polymerization and coordination-insertion polymerization.

Breakthrough in localization! This critical material will go into production this year. 2025-01-15 09:11 · Chemical New Materials. The [Chemical New Materials] team has published a series of articles on such critical materials (such as OLED emitting materials, electronic specialty gases, COC/COP, photoresists, EVOH, etc.). This article will introduce another such critical material, ethylene-acrylic acid copolymer (EAA), from aspects such as its production process, capacity layout, application areas, and future development prospects. What is EAA? Ethylene-acrylic and acrylate copolymers are a class of thermoplastic polymers. Generally speaking, they include ethylene-acrylic copolymers (EAA), ethylene-methyl acrylate copolymers (EMA), ethylene-ethyl acrylate copolymers (EEA), ethylene-butyl acrylate copolymers (EBA), and ethylene-methyl methacrylate copolymers (EMMA). Ionic resins, which are formed by cross-linking the product of the copolymerization of ethylene with acrylic or methacrylic acids using polyvalent metals, are also created through the copolymerization of ethylene with the corresponding acrylic and acrylate monomers. Ethylene-acrylic acid copolymer (EAA) is a random copolymer formed by the polymerization of non-polar crystalline ethylene monomers and highly polar amorphous acrylic acid monomers in the presence of an initiator. Its molecular structure is characterized by carboxyl groups distributed randomly along the main chain and side chains of ethylene; this allows it to bind readily with polar substances, thereby providing excellent adhesion and toughness. The molecular structure of EAA: Compared to polyethylene, the vinyl monomer chains of EAA contain acrylate monomers as well. The molecular movement in its amorphous region is influenced by both the crystalline regions formed by the vinyl chains and the hydrogen bond interactions between the carboxyl groups; this disrupts the original crystalline structure, increases the distance between molecular chains, and enhances its softness and elasticity. Compared to non-polar polyolefin homopolymers, introducing polar functional groups into the polyolefin chains can significantly improve properties such as the dyeability, adhesion, and compatibility of the polyolefin materials. Compared to ethylene-vinyl acetate (EVA), ethylene-acrylic acid and ester copolymers possess higher thermal stability as well as a wider range of processable conditions, and are widely used in fields such as adhesives, packaging materials, high-voltage cable materials, and blended modified materials. Research on the production process of EAA began in the 1950s, with researchers focusing primarily on the copolymerization reaction of ethylene and vinyl acetate (VA). By introducing vinyl acetate monomer, researchers found that it was possible to significantly improve the polarity, flexibility, and heat-sealing properties of ethylene copolymers. This discovery laid the foundation for the industrial production of EAA. In 1961, Dow Chemical Company in the United States, in collaboration with UCC (United Carbon Carbide) of the same country, achieved the industrial production of EAA for the first time, producing EAA resin using the high-pressure bulk method. The content of acrylic monomer (AA) has a significant impact on the properties of EAA; it is usually in the range of 2–20%. As the AA content increases, its transparency, toughness, adhesiveness, and resistance to environmental stress cracking improve, whereas its rigidity, moisture vapor transmission, creep resistance, and chemical resistance decrease accordingly. Therefore, precisely controlling the AA content during the preparation process is key to obtaining the desired properties of EAA. Currently, the main production methods for EAA are free-radical polymerization and coordination-insertion polymerization. Free radical polymerization is the main production method for EAA. It involves the free radical copolymerization of crySTALLine acrylic acid and ethylene as the primary raw materials, under high temperature and pressure conditions (150–300°C, 150–300 MPa). Oxygen or organic peroxides are used as initiators. This process takes place under extreme high temperature and pressure, and the polymerization reactors are typically high-pressure stirred-tank reactors or ultra-high-pressure tubular reactors. The batch process is widely used in industry for production, as it allows for better control over the reaction conditions (temperature, pressure, and monomer concentration), resulting in a homogeneous copolymer. In a continuous tubular reactor, the variation of the reaction mixture along the length of the tube can lead to a non-homogeneous mixture, affecting product quality. Furthermore, in addition to high equipment costs and poor production safety, free-radical polymerization usually results in a wide molecular weight distribution of the copolymers and an irregular microstructure.

The coordination insertion polymerization method has been developed by researchers in recent years to overcome the high technical barriers and patent restrictions; it enables the use of new post-transition metal catalysts to produce ethylene-acrylic acid and ester copolymers under mild polymerization conditions. The use of coordination catalysts (such as Ni or Pd cationic catalysts with diamines as ligands, and catalysts with phosphonic acids as ligands) can effectively reduce the temperature and pressure required for polymerization, and the structure of the polymer can be controlled by altering the structure of the catalyst. However, the molecular weight of the EAA copolymers obtained using the existing catalysts is not high enough, and the incorporation rate of polar monomers is limited, failing to meet the concentration requirements of current products; thus, they are not suitable for industrial production.

Our country relies heavily on imports. According to statistics, the global production capacity for EAA is currently around 300,000 tons per year, with an output of about 250,000 tons. The global EAA market is primarily dominated by companies such as DuPont in the United States (72,000 tons per year), Ineos (57,000 tons per year), Mitsubishi Chemical in Japan (56,000 tons per year), the SK Group in South Korea (operated by its subsidiary SKGC), and ExxonMobil in the United States (28,000 tons per year). These overseas producers account for over 80% of the world’s total production capacity. SKGC entered this industry in 2017 after acquiring the EAA business from Dow Chemical in the United States; it currently has two EAA production facilities, one in Texas, USA, and another in Tarragona, Spain, with a total annual production capacity of 60,000 tons. Additionally, the main grades of EAA products include Exxon ESCOR™, DuPont NUCREL™, SK PRIMACOR™, and others. At present, most domestic ethylene-acrylic acid and ester copolymers rely on imports from abroad, with prices ranging from 20,000 to 30,000 yuan per ton.

Downstream market applications: In terms of the industrial chain, the raw materials for EAA are primarily ethylene and acrylic acid. Thanks to its excellent heat-sealing properties and tear resistance, as well as its ability to prevent the entry of air and moisture, it functions as a high-performance adhesive resin that can bond together various materials such as metals, plastics, paper, and other plastics. Downstream, it is used in areas such as electric vehicle battery electrodes and separators, food and pharmaceutical packaging, and hot melt adhesives; it can also be applied to wires and cables, steel coatings, etc. Additionally, blending modification is also possible, such as blending with olefin polymers or engineering plastics, to improve their low-temperature flexibility, environmental stress cracking resistance, and impact resistance. Due to its excellent notched impact strength, superior weather resistance, and outstanding filler absorption properties, it can be widely used in the modification of flame-retardant ABS, nylon, and PBT.

What will the future development be like? In terms of market size, relevant data show that China currently relies entirely on imports for EAA; the average annual compound growth rate of demand for EAA in China from 2018 to 2023 was 9.9%. The global EAA market size increased from $386.74 million in 2019 to $469.06 million, with a compound annual growth rate of 4.9%. In the future, it is expected that the global scale will reach 531.30 million dollars by 2030, with a compound annual growth rate of 6.1% during the period from 2024 to 2030. In terms of demand, it is reported that in 2020 China’s import volume of EAA was between 20,000 and 30,000 tons per year. The annual demand for coating-grade EAA for mid-to-high-end composite flexible packaging materials was around 15,000 tons. In 2021, China’s demand for EAA reached 27,600 tons, while the import volume in 2023 was approximately 30,000 to 40,000 tons per year, of which the import volume of coating-grade products was about 15,000 tons per year. During the same period, China’s demand amounted to 34,200 tons. It is estimated that by 2030, China’s demand for EAA will be around 60,000 tons, with an average annual compound growth rate of 9.4% from 2023 to 2030. Furthermore, in recent years, with the development of electric vehicles in our country and the **active promotion of the use of environmentally friendly degradable materials, the future market potential for EAA is enormous.