Nylon is a high-performance polymer material in traditional industries. In the field of 3D printing, nylon has also become one of the most widely used materials. PA6, PA11, PA12, PA66, etc. often appear in the available materials for 3D printing. In form, it can be divided into powder materials that can be used in powder bed 3D printing technology, such as selective laser sintering (SLS) and multi-jet fusion (MJF); or wire materials that can be used in FDM 3D printing technology.
There are many varieties of polyamides, and nylon PA12 stands out. It has excellent performance and is widely used. Polyamide (PA), also known as nylon (Nylon), is a high-molecular polymer containing amide groups in the repeating unit on the molecular backbone. Nylon can be made into various plastics, and can also be drawn into fibers, and can also be made into films, paints and adhesives. Because nylon has good mechanical properties, heat resistance, wear resistance and other properties, the products can be widely used in many fields such as clothing, industrial silk, automobiles, machinery, electrical and electronic, transportation, packaging industry and so on.
Nylon has a long history and the family continues to grow. In 1935, PA66 was first synthesized in the laboratory. In 1938, DuPont of the United States officially announced the birth of the world's first synthetic fiber and named it nylon. In the next few decades, the nylon family has gradually developed and expanded, and new varieties such as PA6, PA610, and PA11 have emerged. PA6 and PA66 have mature production processes and a wide range of applications, and are still the two types of nylon products with the greatest demand.
Nylon can be divided into aliphatic, semi-aromatic, and fully aromatic according to the chemical structure of the main chain. Aliphatic polyamide is a linear polymer material, which is composed of methyl segments and amide groups alternately linked regularly, and has good toughness. The introduction of aromatic rings in the main chain can restrict the movement of the molecular chain and increase the glass transition temperature, thereby improving the heat resistance and mechanical properties of nylon products. When one of the raw materials of the polyamide, amine or acid, contains a benzene ring, a semi-aromatic polyamide can be prepared, and when both raw materials contain a benzene ring, a fully aromatic polyamide can be prepared. The heat resistance and mechanical properties of semi-aromatic polyamides are enhanced, and have good dimensional stability and solvent resistance. Fully aromatic polyamides have ultra-high strength, high modulus, high temperature resistance, acid and alkali resistance, resistance It has excellent properties such as radiation, but because its highly symmetrical main chain structure contains dense benzene rings and amide groups, its processing performance is slightly inferior, it is difficult to achieve injection molding, and its cost is relatively higher.
Compared with conventional varieties, special nylon with new synthetic monomers has more excellent performance. Conventional nylon (PA6, PA66, etc.), even after being modified by reinforcement and flame retardancy, still have shortcomings such as strong hydrophilicity, high temperature resistance, poor transparency, etc., which limits its scope of application to a certain extent. Therefore, in order to improve the shortcomings of conventional nylon and add new characteristics, generally by introducing new synthetic monomers, a series of special nylons with different properties can be obtained to adapt to more usage scenarios. These specialty nylons include high-temperature nylons, long carbon chain nylons, transparent nylons, bio-based nylons, and nylon elastomers.
The advantages of PA12 in long carbon chain nylon highlight
Long carbon chain nylon has excellent performance, and nylon 12 has both performance and cost advantages. Nylon with a methylene length of more than 10 between 2 amide groups in the nylon molecular backbone is called a long carbon chain nylon. The main varieties include nylon 11, nylon 12, nylon 612, nylon 1212, nylon 1012, nylon 1313, etc. . Nylon 12 is the most widely used long carbon chain nylon. In addition to most of the general properties of general nylon, it has a low water absorption rate, and has high dimensional stability, high temperature resistance, corrosion resistance, good toughness, and easy processing. advantage. Compared with PA11, another long carbon chain nylon material, the price of PA12 raw material butadiene is only one-third of PA11 raw material castor oil, which can be used in most scenarios instead of PA11. Tubes, submarine cables, 3D printing and many other fields have a wide range of applications.
Nylon 12 material performs well in 3D printing. Compared with other materials, PA12 powder has excellent characteristics such as high fluidity, low static electricity, low water absorption, moderate melting point and high dimensional accuracy of the product. Fatigue resistance and toughness can also meet workpieces that require higher mechanical properties, so nylon 12 Gradually become the ideal material for 3D printing of engineering plastics.
In 2017, PA12 was the fourth largest material in the global 3D printing industry, accounting for 5.6%. In 2018, my country's nylon 3D printing material accounted for 14.1%. The future development of nylon 12 materials produced in China will lay the foundation for the development of my country's 3D printing industry.
Technical barriers create high concentration, oligarchs monopolize nylon 12 market
The main production process of nylon 12 is the oxidative oxime method, which has high technical barriers. Nylon 12 usually uses butadiene as the raw material and is produced by ring-opening polycondensation of cyclododecatriene (CDT) and lauryl lactam. The process includes oxidative oxime method, photo-nitrosation method and Snyar method, in which oxidized oxime Chemical method is the mainstream process. The production of nylon 12 by oxidative oximation requires 7 steps including trimerization, catalytic hydrogenation, oxidation, ketonization, oximation, Beckmann rearrangement, ring-opening polymerization, etc., and the entire process uses benzene, fuming sulfuric acid and other toxic For raw materials with high corrosiveness, the ring-opening polymerization temperature needs to be 270-300℃, which makes the production steps more difficult to operate. At present, most of the manufacturers represented by Evonik use the mainstream process route using butadiene as the raw material, and after obtaining the technical license from the British Petrochemical Company, Japan’s Ube Industries Co., Ltd. uses the process of using cyclohexanone as the raw material. The route realizes the industrial production of PA12.
Under the oligopoly, the concentration of nylon 12 industry is extremely high. In the 1970s, nylon 12 was first industrialized by Degussa, the predecessor of Evonik, in Marl. Later, Swiss EMS, Arkema of France, and UBE of Japan (UBE) also The news of industrial production has been announced one after another. The four major manufacturers have firmly mastered the production technology of nylon 12 for nearly half a century. At present, the global production capacity of nylon 12 exceeds 100,000 tons/year, among which Evonik's production capacity is about 40,000 tons/year, ranking first. In 2014, INVISTA submitted a number of patent applications for nylon 12 raw materials, hoping to enter the nylon 12 resin market, but as of now there has been no news of production.
As the competitive landscape is very concentrated, supply-side emergencies will have a greater impact on the supply of the entire market. For example, on March 31, 2012, Evonik’s Marl plant in Germany was leaked due to a butadiene fire, which caused an explosion and affected the production of the key raw material CDT for more than 8 months, resulting in a serious shortage of CDT supply, which in turn led to global PA12 supply. Tension has even caused some downstream automobile manufacturers to start work normally. It was not until the Evonik CDT plant was put back into production at the end of 2012 that the supply of nylon 12 gradually recovered.
To meet strong demand, the giant announced plans to expand production. In order to meet the strong downstream demand for PA12 materials, Arkema France announced in 2018 that it will increase its global PA12 material production capacity by 25% in Changshu Park, China, and it is expected to be put into production in mid-2020. German Evonik also announced an investment of 400 million euros in the Marl Industrial Park to expand its PA12 material 50% capacity, and plans to start operations in early 2021.
China nylon industry development status
Chinese companies have tackled long carbon chain nylons, and some varieties have made breakthroughs. In the 1950s, China began to try to localize the production of special nylon represented by long carbon chain nylon. The nylon research team of Zhengzhou University and the Institute of Microbiology of the Chinese Academy of Sciences jointly undertook the national key scientific and technological research plan, and developed biological fermentation. Industrial production technology of PA1212 prepared by dodecane dibasic acid, and cooperated with SDGT Chemical Technology Group to achieve industrial production, SDGY New Materials Technology Group realized commercial production in PA610, PA612, PA1012 and other varieties.
In 1977, Jiangsu Huaiyin Chemical Industry Research Institute and Shanghai Institute of Synthetic Materials cooperated with butadiene as the raw material for the synthesis of nylon 12. Subsequently, Baling Petrochemical Co., Ltd. (former Yueyang Petrochemical Plant) conducted a pilot synthesis study of nylon 12 using cyclohexanone as the raw material, breaking the import monopoly pattern of PA12.
SDWH Chemical Technology Group actively deploys nylon PA12
Since 2012, the company has started to apply for patents related to nylon 12 materials. There are two difficulties in the production of nylon 12. First, the oximation reaction process is complicated, the reaction efficiency is low, and there are difficulties in the two-phase liquid separation of the oil at the end of the reaction. In addition, Beckman rearrangement is the most important production link. Has played a key role. In response to these two production difficulties, the patents owned by SDWH have covered all the key steps in the preparation of nylon 12 by oximation of butadiene. In 2013, Wanhua Nylon 12 small pilot project was officially launched. Due to the complicated process of the entire industrial chain of the nylon project, Wanhua set up multiple parallel R&D teams, and each reaction unit carried out research at the same time to improve the research efficiency. At the same time, the R&D work of the project team also established an industry-university-research project with universities, and conducted more than 100 external inspections and exchanges. Finally, a process route with higher yield, less waste, and a more gentle process was selected, which laid a solid foundation for the breakthrough of nylon 12 technology. basis.
The SDWH Nylon 12 project with an annual output of 40,000 tons is located in Yantai Industrial Park, Shandong. It will take advantage of the low domestic raw material prices and the flexibility of independent development within the park. In addition, the company has continued its integrated development thinking. The main raw material of the project, butadiene, is a by-product of the million-ton ethylene project under construction, which not only improves the added value of the entire industrial chain, but is also expected to effectively reduce the value of nylon 12. Cost of production.