Domestic polyoxymethylene manufacturers and technical information

Main manufacturers: China Yuntianhua Group, China Nantong PTM Engineering Plastics Company, China Zhangjiagang DuPont, Asahi Kasei Corporation, China National Chemical Corporation Shanghai Lanxing Company, Henan Yongmei Group, Tianjin Bohai Chemical Group, Shenhua Ningmei Group, Xinjiang United Chemical Group, Chongqing Changshou Yuntianhua Co., Ltd., Inner Mongolia Tianye Chemical Company. The first five are already in operation, while the others are under construction

The annual production capacity of 60,000 tons of polyoxymethylene for the Ningxia Coal Group’s project requires an investment of 1.7 billion yuan; the project covers an area of 12.9 hectares. It uses methanol as raw material and employs the copolymerization technology for polyoxymethylene developed by Fu Yi International Engineering Company to produce this substance, which is one of the key products in the field of fine chemicals. The production process mainly includes steps such as formaldehyde preparation, formaldehyde concentration, pentaerythritol, and polymerization. Construction of this project officially began in August 2009, and by the end of 2010 the mechanical installation for the entire plant was largely completed. The group company’s project to produce 60,000 tons of polyoxymethylene per year gradually entered the commissioning phase, with the cleaning of the pipeline network starting on March 16.

Fuyi International Engineering Co., Ltd. (BDI was established in 1986, with its registered address in **; the company has an office in Beijing.) It is an internationally operating engineering company with its headquarters in **, and it has branches in Taiwan and the Chinese mainland; its Beijing office was established in 2003. It is mainly engaged in technical development and transfer in the petrochemical industry, engineering design, procurement of equipment and materials, installation and commissioning technical guidance, as well as engineering technical consulting. It is mainly engaged in the research and development of chemicals, engineering plastics, and polymer materials. It has established extensive business relationships with many clients in Asia and Europe, boasts years of experience in design and engineering, and has a solid track record of success. Its technology was primarily developed based on the techniques used in Taiwan’s POM factories. In China, they cooperate only with the Fourth Chemical Research Institute (Wuhuan); the production capacities resulting from these collaborations are 20,000 tons per year for Lanxing, 40,000 tons per year for Tianjian, 40,000 tons per year for Kaifeng Longyu (with a second phase planned to reach 60,000 tons per year, and the contract has already been signed), and 60,000 tons per year for Shenhua Ningmei.

Thank you for the information, OP; I understand now.

Tianye Chemical’s Lines A/B have been successfully put into operation, while Line C is in the process of accelerated trial operation

Yunnan Yuntianhua Co., Ltd. is a joint-stock company established through public fundraising, initiated solely by Yuntianhua Group Co., Ltd. In July 1997, Yuntianhua’s A-share shares were listed on the Shanghai Stock Exchange. It is one of China’s top 100 listed companies, as well as an outstanding producer of copolymerized formaldehyde and a leading manufacturer of glass fiber worldwide. As of September 2010, the company had total assets of 22.5 billion yuan and net assets of 6.5 billion yuan. In addition to establishing a production facility in Shuifu County with an annual output of 30,000 tons, Yuntianhua Co., Ltd. has also invested over 1.5 billion yuan in Chongqing to set up a deep-processing facility for polyoxymethylene materials, with an annual production capacity of 60,000 tons. In 2009, Yuntianhua’s sales volume of polyoxymethylene reached over 40,000 tons, giving it a market share of around 38% in the domestic market. With the full operation of the 90,000-ton production line, sales are expected to exceed 60,000 tons this year. Products of the M25 grade have been successfully produced, making the company the only one in the country capable of manufacturing this brand. As the only manufacturer in China capable of producing M25 grade polyoxymethylene, Yuntianhua’s product quality has now been recognized by the American company DuPont. The number of grades of polyoxymethylene products exported by this company has also increased to 4, including M25, M120, M90, and M270. These products are exported to more than 30 countries in Europe, the Americas, Oceania, and Asia, and the volume of orders is rising year by year. Yuntianhua exported 1,000 tons last year.

Technical characteristics of polyoxymethylene technology abroad: 1. DuPont in the United States – The homopolymerization process represented by DuPont in the U.S. uses a 50% concentration formaldehyde solution as raw material. Due to the presence of water and other impurities in this formaldehyde, it is combined with isooctanol to form an ethyl hemihydrate formaldehyde solution; after dehydration and purification, thermal cracking is carried out to obtain pure formaldehyde. It is introduced into an inert solution containing an ethyl ether complex of boron trifluoride to undergo polymerization to yield homopolymerous formaldehyde. The polymerized material is separated by filtration, dried, and then its hydroxyl groups are esterified using acetic anhydride to achieve thermal stability of the polyformaldehyde. Subsequently, additives such as antioxidants are added, and the final product is obtained through extrusion granulation. Due to the complexity of the formaldehyde purification process and the difficulties associated with post-treatment for end-capping, this production route results in polymeric products with poor alkali and heat resistance, as well as high production costs. Owing to technical and economic considerations, some foreign companies that previously used the polymerization method for producing polyformaldehyde, such as Italy’s SIR company and Japan’s Asahi Kasei Company, have switched to the copolymerization method for their polyformaldehyde production facilities. 2. American Ticona: American Ticona utilizes Celanese’s polyoxymethylene technology, and its main production process is as follows: ferro-molybdenum method for producing formaldehyde, which is then concentrated to 60%. Formaldehyde trihydrate with sulfuric acid as catalyst. Separation and purification to 99.9% is achieved through extractive distillation using α-chloronaphthalene as the extractant. Cyclohexylamine solvent and ethylene oxide comonomer were added to the solution polymerization reactor at 150% and 5% of the mass percentage corresponding to the amount of triomethylenetetramine added, respectively; simultaneously, a boron trifluoride etherate polymerization catalyst at 120 PPM was added. Most of the ethylene oxide and 70% of the triomethylenetetramine copolymerized to form a copolymer with an average molecular weight of approximately 40,000. At 70°C, after 2–4 hours, tri-n-butylamine with a mass fraction of 0.5% was added to terminate the reaction. The filtered and dried polymer solids were reconverted into a slurry using 5 times their weight in water. Add 5% of ammonia water based on the weight of the slurry. The slurry is heated to 150°C, and ammonia degrades formaldehyde at the ends of the polymer chains. The stable polymer is pumped through a flushing centrifuge and rinsed with fresh water. Then it is steam-dried using a roller dryer. In the extrusion equipment, extrusion molding is carried out, during which stabilizers and antioxidants are added. The 0.125 inch (0.3 cm) pellets produced by the granulator are bagged using gas conveying. 3. German company BASF: BASF in Germany uses the bulk polymerization process, with twin-screw extruders being employed as the polymerization equipment in the reactors; boron trifluoride or trifluoromethanesulfonic acid is used as the catalyst. After exiting the polymerization reactor, the copolymer is cooled with water and then sent to a cutting chamber where it is cut into particles; subsequently, a centrifuge is used to separate the liquid from the particles. Finally, it is dried using a fluidized bed dryer to obtain copolymerized formaldehyde. 4. Japanese company Polyplastic: Polyplastic is the largest POM producer in Asia. Currently, 70% of the polyoxymethylene produced is in unreinforced grades, and these grades face fierce competition in international markets. To address this, Polyplastic utilized its own proprietary polymerization techniques and crystal control methods to introduce a new grade called Duracon HPgOx to the market in November 2002. This new grade incorporates \"copolymers\" into the polyoxymethylene molecular chains, thereby enhancing the resin’s thermal and chemical stability. It has a crystalinity that is more than 10% higher than that of traditional copolymer grades, yet it still retains excellent mechanical properties, particularly high toughness. Under certain loads, the long-term creep resistance life of its products is 10 times higher than that of ordinary grades (M25S). 5. Asahi Kasei Corporation, Japan: Asahi Kasei uses a catalytic synthesis process based on paraformaldehyde as the monomer. This process consists of five steps: purification of the paraformaldehyde monomer, continuous polymerization of the solution, continuous esterification for end-capping, extrusion granulation of the product, and solvent recovery. High concentrations of formaldehyde help to increase the synthesis rate and equilibrium concentration of triomethylenetetrahydrofuran. In the process in which 70% formaldehyde is obtained directly through the oxidation of methyl aldehydes, the synthesis reaction takes place at relatively low temperatures (60–90°C); almost no formic acid is produced, and there is no risk of equipment corrosion. Furthermore, since the formaldehyde content obtained from the reaction reaches 70%, this facilitates an increase in the reaction rate of paraformaldehyde synthesis and reduces side reactions. 6. Nippon Yusen Kogyo Company: By combining the technological features of DuPont and Celanese, Yusen Kogyo developed a continuous gas-phase copolymerization process. Its gas-phase polyoxymethylene synthesis method, which does not require solvents during polymerization, is highly distinctive; this technology has low requirements regarding material specifications, features a simple process flow, and generates little corrosion. The gas-phase copolymerization of formaldehyde technology developed by Ube Industries consists mainly of formaldehyde synthesis, monomer preparation, copolymerization, stabilization, and recovery of dilute aldehydes. Its technical features are as follows: the raw material methanol is used to produce 50% formaldehyde via air oxidation; this formaldehyde is then dehydrated, thermally decomposed, and refined to yield purified formaldehyde gas. High-purity purified formaldehyde gas is mixed with the copolymer monomer polyethylene glycol ether, and then fed into a twin-screw reactor under the presence of a boron trifluoride-ether complex for continuous polymerization. At temperatures of 40–70°C, a molecular weight regulator is added to produce specific copolymerized polyoxymethylene powders. The high-temperature cyclic polyoxymethylene powder discharged from the polymerization reactor is cooled and sent back to the reactor for recycling in order to control the polymerization temperature; thereafter, the polyoxymethylene powder is transported by a screw conveyor to the stabilization process. The material is then treated with a stabilizing solution at 130–160°C to remove the unstable end groups, thereby producing a stabilized slurry; subsequent steps such as filtration, drying, and granulation yield the final product of copolymerized formaldehyde. 7. LG Chem of South Korea – South Korea’s LG has the largest range of modified polyoxymethylene grades available abroad; these grades contain sterically hindered phenolic antioxidants in amounts of 0.01–3% wt based on the polyoxymethylene content ； Based on polyoxymethylene, 0.001–0.3% wt of polyamide ； Based on polyoxymethylene, 0.001–0.5% by weight of magnesium oxide with a specific surface area of over 10 m2/g can improve the functional impairments caused by formic acid generated during the modification process. The process route is as follows: Gas-phase polymerization is employed; methanol is oxidized with air to produce 50% formaldehyde. Formaldehyde then reacts with polyethylene glycol, and after dehydration and thermal decomposition, pure formaldehyde gas is obtained. Pure formaldehyde gas, trioxane, and polyethylene glycol undergo copolymerization in a twin-screw reactor at temperatures of 40°C–70°C, using a boron trifluoride-ether complex as a catalyst, to yield crude polyoxymethylene. After the reaction is complete, the crude polyoxymethylene is subjected to stabilization treatment to yield the resin powder. In 2007, all of LG Chem’s POM production facilities in Ulsan, South Korea, were relocated to Qatar in the Middle East, and LG Chemical’s polyoxymethylene production capabilities as well as its technologies for modifying polyoxymethylene were transferred to the South Korean company P&ID. Four key technical staff members from PID Company work at the polyoxymethylene plant of the company in Qatar. Due to the need to make full use of the existing equipment and the limitations in further increasing the capacity of the facility, the capacity of the Qatar plant has increased by only 50% compared to before the relocation. It is currently producing medium-density and low-density products, with LG Corporation still being responsible for selling these products under its brand. 8. Mitsubishi Corporation, Japan: Mitsubishi in Japan uses a fixed-acid liquid-phase synthesis process, which employs a formaldehyde-dichloroethane solution obtained through azeotropic dehydration as the raw material for synthesis, thereby eliminating the impact of water on the synthesis yield. The one-way yield of trioxane is generally 38.9%. This process has few side reactions, allowing the process to be **simplified, and it enables concentration, synthesis, and purification to be combined into one step. The process route is as follows: the copolymerization raw materials are triomethylenetetraoxane and epoxide pentane, with a molar ratio of epoxide pentane to triomethylenetetraoxane ranging from 9% to 15%; the catalyst used is boron trifluoride, and molecular weight regulators such as methyl acetal are also added. A continuous twin-screw mixer reactor was selected for the reaction, as this allows for an increased residence time of the raw materials and thus a higher conversion rate of the reactants. A new liquid-phase hydrolysis process was employed in the stabilization step of the product. The stability of the products obtained through the liquid-phase hydrolysis process is improved compared to that obtained using the melt stabilization process. 9. KEP Corporation in South Korea has adopted the process technologies from Mitsubishi’s original 10,000-ton facility. Starting with the construction of the 40,000-ton facility in 2001, P&ID Corporation began to scale up the process simulations and carry out the preliminary design work; today, KEP Corporation’s polyoxymethylene production capacity has reached 100,000 tons per year. The technical features of its polyoxymethylene process are as follows: the formaldehyde production unit employs an inert gas exhaust gas recycling process for the formaldehyde production. The concentration of the formaldehyde solution is high. The formaldehyde concentration unit employs new technologies of pressurized vaporization and reduced-pressure flashing, replacing the traditional vacuum falling-film process; it features stable operation and high formaldehyde concentrations. The high-temperature gas at the top of the triomethylenemethane reaction distillation tower is used as a heat source for formaldehyde concentration, which reduces the amount of steam required for formaldehyde concentration and also decreases the amount of circulating water needed in the condenser at the top of that tower. The polyoxymethylene purification unit features a short process flow, few pieces of equipment, and high purity of polymeric-grade polyoxymethylene. The polymerization unit uses twin-screw machines; the copolymer is made of trioxane, and the catalyst is supplied in the form of a non-viscous liquid. The mixing uniformity is excellent, as is the stability of the polymerization molecular chains. The key is to remove the copolymer in a timely manner and to open the carbon-carbon double bonds; this process enables efficient removal of the heat of polymerization, allowing for temperatures low enough while still ensuring the residence time required for the desired chain length. The polymerization equipment used has a smooth surface, which prevents crust formation on the inner walls of the reactor. Double-screw extruders use electric heating, while other manufacturers abroad employ heat transfer oil or superheated steam as the heating source for such extruders. P&ID’s heating technology requires less space, results in lower investment costs, and offers higher efficiency. II. Technical Characteristics of Polyoxymethylene in China 2.1. Jishihugou Integrated Chemical Plant of CNPC At the end of 1965, the Jishihugou Integrated Chemical Plant utilized the research results from the Changchun Institute of Applied Chemistry to produce China’s first batch of copolyoxymethylene in 30L reactors; by 1992, its production capacity had reached 1,000 tons per year. After Jihua Company and China National Petroleum Corporation were reorganized in 1998, the polyoxymethylene production facility at Shijingou United Chemical Plant was shut down. The process involves using formaldehyde with a concentration of 65%–70%; under acidic catalysis, triomethylenetetrahydrofuran is produced. Given that triomethylenetetrahydrofuran has a boiling point of 63°C and is soluble in water, with its solubility increasing as the temperature rises, melting, freezing, crystallization, separation, and distillation methods are employed to obtain 99.5% pure triomethylenetetrahydrofuran. The refrigerant uses a (-9°C ethylene glycol aqueous solution, which is frozen and crystallized, followed by centrifugal separation and filtration). Triomethyleneglycol and a small amount of the comonomer pentaerythritol undergo ring-opening polymerization in the presence of molecular Lewis acids that can provide electron clouds to form copolyomethyleneglycol. The polymerization is carried out using twin-screw reactors; after grinding, most of the chain ends of the copolyomethyleneglycol are hemiacetal groups, which are thermally unstable. These ends are sealed using ammonia in a batch reactor, and antioxidants and other additives are added for stabilization purposes. Finally, the material is dried, mixed, and granulated to produce the copolyomethyleneglycol product. 2.2. The polyoxymethylene production plant of Yunnan Natural Gas Chemical Group Company, Yuntianhua Co., Ltd., was the first of its kind in China. In 1997, Yuntianhua entered into a technology transfer agreement with the Polish company ZAT, and the plant was put into operation in July 2001. In the iron-molybdenum method for producing formaldehyde, formaldehyde is concentrated to 60% concentration to yield triomethylolpropane; sulfuric acid is used as a catalyst. The purification of triomethylolpropane is carried out using melt freezing and crystallization separation technology, which is the same as the technique used by Jihua for purifying triomethylolpropane. However, the low purity of triomethylolpropane results in customers reporting poor thermal stability of the product, as well as a strong odor of formaldehyde during the injection molding process. At present, Yuntianhua has not yet produced high-density polyoxymethylene products. Alkali extraction for purification: Distillation yields 99.9% trimethylolpropane. 2.3. Shanghai Lanxing Chemical New Materials Factory: Shanghai Solvent Factory built a 100t/a plant in 1970. After years of research and development, the plant’s production capacity reached 1,900 t/year in 2000. In 2003, Shanghai Solvent Factory was reorganized together with Lanxing Company of Sinopec Group. First, discussions were held with the Polish company ZAT regarding technology transfer, and negotiations progressed to the point where a contract for technology transfer was signed; later, a technology transfer contract was concluded with **Fuyi Company. In 2005, construction began on the 60,000 tons per year polyoxymethylene production facility, with the Fourth Research Institute responsible for the engineering design and China National Offshore Oil Chemical Co., Ltd. handling the construction work. The main problems that have occurred so far are as follows: 1) Large amounts of by-products and polymers are generated during the synthesis of triomethylenemethane; 2) There is a low concentration of reactants in the reactor used for triomethylenemethane synthesis; 3) The polymerization efficiency in the single-series reactors is low; 4) Polymerization often stops after the addition of dioxolane. 2.4. Inner Mongolia Tianye Chemical Co., Ltd. During the feasibility study phase, Tianye used Fuyi technology, but later switched to Polish technology. Since the technology transfer agreement between Poland and Xinjiang United Chemical was its last contract in China, it became impossible for Tianye to continue using Polish technology. Therefore, the technology of Sichuan Chengda Company was used during the engineering design phase. There is a problem here: Sichuan Chengda Company is responsible for the detailed design of Yuntianhua’s polyoxymethylene production facility, but it does not have knowledge of the technical improvements made by Yuntianhua. If the technical adjustments applied to Yuntianhua’s polyoxymethylene production process are not used to improve Poland’s ZAT polyoxymethylene technology, then Amano will have to follow the same path that Yuntianhua took, and will have to pay the associated costs. 2.5. Nantong PTM Engineering Plastics Company in China: A polyoxymethylene production facility with the largest scale among foreign facilities to date, capable of producing 60,000 tons per year, was established in the Nantong Economic and Technological Development Zone through a joint investment of $140 million by four renowned foreign multinational companies: Japan’s Boron Engineering Plastics Co., Ltd., Mitsubishi Gas Chemical Corporation of Japan, Korea Engineering Plastics Co., Ltd., and Tegon Corporation of the United States. The facility began operations in 2006. 2.6. DuPont in Zhangjiagang, China, and Asahi Kasei in Japan: Asahi Kasei of Japan and DuPont of the United States jointly funded the construction of a homopolymer oxymethylene plant; work began in Zhangjiagang City, Jiangsu Province, in 2002, and the plant came online in the spring of 2005. The facility is held by Asahi Kasei and DuPont China Holdings in equal shares of 50% each, with an initial production capacity of 20,000 tons per year of polyoxymethylene. 2.7. Triomethylene formaldehyde synthesis technology at Lanzhou Institute of Chemical Physics In January 2009, an industrial-scale trial to synthesize triomethylene formaldehyde using the LZT-I type ionic liquid catalyst was carried out at CNOOC Hainan Dongfang pilot plant, and qualified triomethylene formaldehyde was produced. Compared with traditional techniques, the ion liquid synthesis method allows the concentration of paraformaldehyde in the reaction solution to reach 38%, **which is higher than the concentration of paraformaldehyde in solutions obtained using the sulfuric acid method. It can reduce environmental pollution and equipment corrosion, as well as lower investment costs. 2.8. Comprehensive Evaluation of Domestic Polyoxymethylene Production Technologies **It will take some time before the polyoxymethylene production facility built by Fuyi Technology can operate properly; meanwhile, Yuntianhua’s polyoxymethylene production is constrained by the TOX purification process, resulting in higher consumption levels and product performance that are still far behind those of world-class technologies. Given the stagnation in the technical level of domestically produced polyoxymethylene, it is expected that foreign countries will continue to impose technical barriers on our country in the coming years; foreign polyoxymethylene products will thus remain dominant in our market for a long time, with little chance of any fundamental change. Kep technical features ZAK technical features Kep technical features ZAK technical features POM

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