Nylon is a high-performance polymer material in traditional industries.
In the field of 3D printing, nylon has become one of the most widely used materials.
PA6, PA11, PA12, PA66 and so on are often used in the available materials of 3D printing.
In form, it is divided into powder materials that can be used for powder bed 3D printing technology, such as selective laser sintering (SLS) and multi-injection fusion (MJF).
Or wires that can be used for FDM 3D printing.
It is noted that Changjiang Securities Research Institute issued a report “Wanhua Chemical (600309) Series report: Nylon 12: Bright Pearl of Materials, Breaking Foreign Capital Monopoly”, which makes a very in-depth analysis and introduction of 3D printing material polyamide PA nylon, which is worth reading.
With a wide variety of polyamides, nylon PA12 stands out
Nylon has excellent properties and is widely used.
Polyamide (PA), also known as Nylon, is a kind of polymer with amide group in the repeating unit on the molecular backbone.
Nylon can be made into all kinds of plastics, and can be brushed into fiber, can also be made into film, paint and adhesive, etc.
Because nylon has good mechanical, heat resistance, wear resistance and other properties, products can be widely used in clothing, industrial silk, automobile, machinery, electronics, transportation, packaging industry and many other fields.
The nylon family grew
Nylon has a long history and a growing family.
In 1935, PA66 was first synthesized in the laboratory. In 1938, dupont announced the birth of the world’s first synthetic fiber and named it nylon.
In the following decades, the nylon family gradually developed, PA6, PA610, PA11 and other new varieties appeared.
PA6 and PA66, with mature production processes and wide application fields, are still the two types of nylon products in greatest demand.
Nylon chemical structure
Molecular structure of different polyamides.
Nylon can be divided into aliphatic, semiaromatic and whole aromatic groups according to the chemical structure of the main chain.
Aliphatic polyamide is a linear polymer material, which is composed of methyl segment and amide group and has good toughness.
The introduction of aromatic ring in the main chain can restrict the movement of molecular chain, improve the glass transition temperature, and thus improve the heat resistance and mechanical properties of nylon products.
Semi-aromatic polyamides can be prepared when one of the raw materials amine or acid contains benzene ring, and full aromatic polyamides can be prepared when both raw materials contain benzene ring.
Half of aromatic polyamide heat resistance and mechanical properties are enhanced, and good dimensional stability and solvent resistance, the aromatic polyamide with high strength, high modulus, high temperature resistant, acid and alkali resistance, radiation resistance and other excellent performance, but because of its high symmetry is contained in the main chain structure of the concentration of benzene and amide groups, therefore slightly smaller on the machining performance is difficult to realize the injection molding, the cost is relatively higher.
Classification and characteristics of polyamides.
Source: China Textile Industry Research Institute, Structural Properties and Applications of semi-aromatic Nylon, Changjiang Securities Research Institute
Kinds and characteristics of special nylon.
Compared with the conventional varieties, the new synthetic monomer of special nylon has better performance.
Conventional nylon (PA6, PA66, etc.) still has some shortcomings such as strong hydrophilicity, high temperature resistance, poor transparency and so on, which limit its application scope to some extent.
Therefore, in order to improve the shortcomings of conventional nylon and add new features, a series of special nylon with different properties can be obtained by introducing new synthetic monomers, so as to adapt to more usage scenarios.
These special nylon include high temperature nylon, long carbon chain nylon, transparent nylon, bio-Kininon and nylon elastomer, etc.
The advantage of PA12 in long carbon chain nylon is prominent
Long carbon chain nylon has excellent performance, nylon 12 has both performance and cost advantages.
Nylon with methylene length above 10 between two amide groups in the main chain of nylon molecule is called long carbon chain nylon. Main varieties include nylon 11, nylon 12, nylon 612, nylon 1212, nylon 1012, nylon 1313 and so on.
Nylon 12 is the most widely used long carbon chain nylon. In addition to the general properties of nylon, it has low water absorption, high dimensional stability, high temperature resistance, corrosion resistance, good toughness, easy to process and other advantages.
Compared with PA11, another long carbon chain nylon material, the price of PA12’s raw material butadiene is only one third of that of PA11’s raw material castor oil. It can replace PA11 and be used in most scenarios. It is widely used in automobile fuel pipe, air brake hose, submarine cable, 3D printing and other fields.
Nylon 12 works well in 3D printing.
Compared with other materials, PA12 powder has excellent properties such as high fluidity, low static electricity, low water absorption, moderate melting point and high dimensional accuracy of the products. Fatigue resistance and toughness can also meet the requirements of workpiece with high mechanical properties. Therefore, nylon 12 has gradually become an ideal material for engineering plastic 3D printing.
According to the statistics of Foresight Industrial Research Institute, PA12 was the fourth largest material in the global 3D printing industry in 2017, accounting for 5.6%, and nylon 3D printing material accounted for 14.1% in China in 2018.
The future development of domestic nylon 12 materials will lay a foundation for the development of China’s 3D printing industry.
Technical barriers create a high degree of concentration, oligopoly nylon 12 market, nylon 12 mainstream production process is oximation method, technical barriers are high.
Nylon 12 is usually made from butadiene by cyclododecatriene (CDT) and lauramide open-loop polycondensation. The processes include oximation, photonitrification and Snia process, of which oximation is the main process.
The production of nylon 12 by oximation requires 7 steps, such as trimerization, catalytic hydrogenation, oxidation, ketoxification, oximation, Beckman rearrangement, and ring opening polymerization. In addition, toxic and corrosive raw materials such as benzene, fuming sulfuric acid and other materials are used in the whole process. The temperature of ring opening polymerization is 270-300℃, making the production procedure difficult to operate.
At present, most of the manufacturers represented by Wincreate are using the mainstream process route with butadiene as raw material, while Ube Xingxing, a Japanese company, has realized the industrial production of PA12 by using the process route with cyclohexanone as raw material after obtaining the technical license from British Petroleum Chemical Company.
Under oligopoly, nylon 12 industry concentration is very high.
In the 1970 s, nylon 12 first by Evonik industries (Evonik) German degussa company established on the basis of the industrialized production in Marl, then Switzerland EMS Arkema, France (UBE XingChan Arkema) and Japan (UBE) also announced in industrial production, the four major producers have been firmly nylon 12 production technology 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 the first.
In 2014, Invidia submitted a number of patent applications for nylon 12 raw materials, hoping to enter the nylon 12 resin market, but so far there is no production news.
Because the competition pattern is very concentrated, the supply side of the emergency will have a great impact on the supply of the whole market.
For example, on March 31, 2012, a fire and explosion caused by butadiene leak in the factory of Evonik in Marl, Germany affected the production of the key raw material CDT for more than 8 months, resulting in the serious shortage of CDT supply, which further led to the global PA12 supply shortage, and even led to the normal operation of some downstream auto manufacturers.
It was not until the end of 2012, when Evonik’s CDT plant resumed production, that the supply of nylon 12 was gradually restored.
To meet strong demand, the giant announced plans to expand production.
To meet strong demand downstream of PA12 materials, Arkema France announced in 2018 to increase its global production capacity of PA12 materials by 25% in changshu Park, China, and expects to start production in mid-2020.
Germany’s Evonik also announced a €400 million investment to expand its PA12 materials production capacity by 50% in the Marl industrial park, with plans to start operations in early 2021.
With the help of policy, domestic enterprises have risen to the challenge
Domestic enterprises to tackle the long carbon chain nylon, some varieties have made a breakthrough.
In the 1950s, China began to try to domesticate the special nylon represented by long carbon chain. However, due to the complicated process route, harsh production conditions, multiple synthesis steps and high cost, the industrial production of long carbon chain nylon in China remained stagnated until the 1990s.
Nylon during the “ninth five-year plan, zhengzhou university research team and the Chinese Academy of Sciences microbial Shared by the national key research program of science and technology, research and development by biological fermentation twelve carbon preparation technology in the industrial production of PA1212 dibasic acid, and cooperate with shandong zibo guang tong chemical company, realize the industrial production, in addition, shandong province, broad new material co., LTD., also in PA610 nebula-rich complex, PA612, PA1012 varieties such as a breakthrough.
PA12 is more difficult, and a breakthrough is possible with the help of policy.
In 1977, Jiangsu Huaiyin Chemical Research Institute and Shanghai Institute of Synthetic Materials co – operated the synthesis of nylon 12 using butadiene as raw material.
Subsequently, Baling Petrochemical Co., LTD. (the former Yueyang Petrochemical General Factory) conducted a small test synthesis study of nylon 12 using cyclohexanone as raw material. However, as the synthesis route of PA12 is as long as 7 steps and the barriers are very high, domestic enterprises have not yet realized industrial production of PA12, and PA12 is still dependent on imports at present.
In recent years, China has also introduced policies to encourage the development of special nylon industry, and actively promoted the localization process of special nylon materials. With the help of policies, domestic enterprises will continue to grasp the gloves and break the monopoly pattern of PA12.
Wanhua chemical actively layout nylon 12, is expected to usher in the first breakthrough
Years of accumulation, finally welcome breakthrough.
Wanhua Chemical has experienced a long history of development in the field of nylon 12. Since 2012, the company has been applying for patents related to nylon 12 materials.
There are two difficulties in the production of nylon 12. First of all, the oxime-reaction process is complex, the reaction efficiency is low, and the end of the reaction is difficult for oil two-phase liquid separation. In addition, Beckman rearrangement is the most important production link, which plays a key role in the impact on product quality.
Aiming at these two production difficulties, Wanhua is also actively trying to seek a breakthrough and has obtained some related production patents.
Up to now, the patent owned by Wanhua has covered all the key steps in the preparation of nylon 12 by oximation of butadiene.
In 2013, the pilot project of Wanhua Nylon 12 was officially launched. Due to the complex process of the entire industrial chain of the nylon project, Wanhua set up several parallel r&d teams and carried out research in each reaction unit at the same time to improve the efficiency of the research.
At the same time, the research and development work of the project team also established industry-university-Research project with the cooperation of colleges and universities, conducted more than 100 overseas visits and exchanges, and finally selected a process route with higher yield, less waste and gentler technology, which laid a solid foundation for the breakthrough of nylon 12 technology.
The 40,000-ton nylon 12 project is located in Yantai Industrial Park, Shandong Province, and will take full advantage of the low price of domestic raw materials and flexible independent development within the park.
In addition, the company has continued the idea of integrated development. The main raw material of the project is butadiene, a by-product of the million-ton ethylene project under construction, which not only improves the added value of the whole industry chain, but also is expected to effectively reduce the production cost of nylon 12.
This paper is based on the report of Wanhua Chemical (600309) Series of Nylon 12: Bright Pearl of Materials, Breaking foreign Capital Monopoly by Changjiang Securities Research Institute.