Polyoxymethylene

Polyoxymethylene, also known as polyformaldehyde, has the English name polyoxymethylene (abbreviated as POM). The crystallinity resulting from POM’s regular molecular structure gives it excellent physical and mechanical properties, earning it the nickname \"metal plastic\". 　　 POM is a milky, opaque, crystalline linear thermoplastic resin with a high elastic modulus, high stiffness and hardness; its specific strength and specific stiffness are close to those of metals. It also has a low friction coefficient, is wear-resistant, and exhibits good dimensional stability. POM is commonly used as a building material to replace non-ferrous metals such as copper, zinc, tin, and lead, and it is widely applied in industries such as industrial machinery, automobiles, electronics and electrical appliances, daily necessities, pipes and fittings, and precision instruments. The main drawback of POM is its poor flame retardancy; it burns slowly when exposed to fire, and even the addition of flame retardants does not yield satisfactory results. 　　 In addition to homopolymeric POM, it is often copolymerized with ethylene oxide in order to prevent the degradation of POM at higher processing temperatures. Homopolymerous polyoxymethylene has a high degree of crystallinity, and its mechanical strength and rigidity are superior to those of copolymerous polyoxymethylene. Copolymerous polyoxymethylene has a lower melting point, and its thermal stability, flow properties, and processability are better than those of homopolymerous polyoxymethylene. Technical principle and process: A 37% or 55% aqueous formaldehyde solution is first depolymerized, and then a concentrated formaldehyde solution of around 80% is obtained through two-stage falling-film vacuum concentration. After a polymerization reaction takes place under the action of a copolymerization agent, the final polyformaldehyde product with a concentration of around 96% is produced via spray granulation and continuous drying. Level of performance and key technical parameters: Product quality parameters: Formaldehyde content ≥95%, methanol content ≤0.5%, acidity ≤0.8%, ash content ≤100 ppm, melting point 120–175°C, bulk density 600–800 g/L, pH 3.5–5.0, reaction time 5 minutes, solubility (in water at 100°C for 10 minutes) 95%, degree of polymerization 8–30. Tonnage consumption metrics per product: 37% formaldehyde – 2.8 tons, steam – 3.0 tons, cooling water – 200 tons, electricity – 260 kwh. Production scale and output: 20,000 tons/year. Required floor area for the factory: 10,000 m2. Main equipment: depolymerization kettle, falling film evaporator, polymerization reactor, granulation tower, dryer, absorption tower, and cooler, etc. Main raw material and source: formaldehyde. Market analysis and benefit forecasting: As an ideal substitute for formaldehyde, polyformaldehyde has a broad market potential. However, the total domestic production of polyformaldehyde is less than 6,000 tons per year, which is far from sufficient to meet market demand. Henan Zhongyuan Dahua Group Co., Ltd.: 50,000 tons per year – a proposal. Tianzhu Fertilizer Branch of Qingdao Alkali Industry Co., Ltd.: 10,000 tons per year of polyoxymethylene. Shanghai Lanxing Chemical New Materials Factory: 40,000 tons; bidding for custom-made equipment (April 2007). Jiangtian Co., Ltd.’s Nantong branch has already started production of 20,000 tons of polymer. Yichang’s investment promotion efforts: 30,000 tons in the Chutian Chemical Industrial Park in Zhijiang City; 20,000 tons in Yima City, Henan Province. Changshou’s investment promotion efforts: 40,000 tons. Qinghai Province: over 30,000 tons of polymers. Shenyang’s investment promotion efforts: 30,000 tons. Xinjiang United Chemical: 40,000 tons. Tangshan’s investment promotion efforts: 60,000 tons. Dazhou, Sichuan: 60,000 tons of natural gas. Daqing: 40,000 tons

With so many people involved in the production of polyoxymethylene, the competition is fierce

On the 2nd floor, there was a mistake regarding polyoxymethylene and paraformaldehyde. Simply put, polyoxymethylene is a type of plastic, while paraformaldehyde is just the solid form of formalin.

What was said on the fourth floor is correct; moreover, the production method for polyoxymethylene is far more complex than that for polyformaldehyde

I’m going to Yuntianhua; I’ll probably head to the polyoxymethylene production workshop. It’s quite large in scale, hehe~~~ Learning*learning*

Congratulations! I wonder what the environment like is there?

Polyoxymethylene (POM) is divided into two main categories: one is the homopolymer of trimethylolpropane or formaldehyde, known as homopolyoxymethylene; the other is the copolymer of trimethylolpropane and a small amount of pentane, known as copolyoxymethylene. The production process of homopolymerous polyoxymethylene is represented by DuPont Company. Its products have a relative density of around 1.4 and a melting point of 170–185°C. They feature excellent rigidity, with a tensile strength of up to 68.9 MPa; the tensile strength per unit mass is higher than that of zinc and brass. Additionally, they have good wear resistance and a low coefficient of friction. However, they lack thermal stability and are not resistant to acids. In the homopolymerization process, 50% formalin solution is first reacted with isooctanol to produce ethylhexyl hemiformalin solution, which is then dehydrated and thermally cracked to yield refined formalin. Then, liquid-phase polymerization is carried out in a reactor under the catalysis of the BF3o ether complex. After filtration, separation, and drying of the polymer product, it is terminated by esterification with acetic anhydride. High-purity nitrogen is required for protection during the process. The formaldehyde purification process in this technology is complex; the post-treatment end-capping technique presents certain difficulties. The process flow is lengthy, there are many pieces of equipment, and corrosion is severe, requiring expensive alloy materials for the synthesis reactors. The production process for copolymerized formaldehyde is typically represented by the technology of the Hestel-Sellens company; companies such as BASF and Mitsubishi Gas Chemical also have their own technologies. Yubari Kogyo’s solvent-free gas-phase polyoxymethylene copolymerization process during the polymerization stage is also distinctive. A 50% formaldehyde solution was concentrated to 65%, and a triomethylenemethane solution was synthesized in the presence of sulfuric acid; polymer-grade triomethylenemethane was obtained through extraction and purification with a solvent (benzene or dichloroethane). Then, polymeric trimethylene oxide was used as the polymerization monomer, and ethylene oxide (or dioxolane) was used as the copolymerization monomer, to carry out bulk continuous copolymerization using a twin-screw reactor. The resulting copolymer is crushed, subjected to continuous and batch stabilization to remove thermally unstable components, dried, and then mixed with additives for granulation. Asahi Kasei has developed a new process for the direct synthesis of 70% high-concentration formaldehyde through methylal oxidation, eliminating the need for formaldehyde concentration and the recovery of dilute formaldehyde. The formaldehyde produced in the synthesis of triomethylenemethane can be recycled back to the methoxal synthesis reactor. Its methyl acetal synthesis reaction takes place at a low temperature (60–90°C), with almost no formic acid produced, and thus no equipment corrosion occurs. 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. The gas-phase copolymerization of formaldehyde technology developed by Ube Industries consists mainly of formaldehyde synthesis, monomer preparation, copolymerization, stabilization, and solvent recovery. The process route is as follows: The raw material methanol is oxidized with air to produce 50% formaldehyde, which then reacts with polyethylene glycol; after dehydration, thermal decomposition, and purification, purified formaldehyde gas is obtained. The purified formaldehyde gas is mixed with the gaseous comonomer octacyclotrioxane and then fed into a twin-screw reactor for copolymerization. The high-temperature cyclic polyoxymethylene powder discharged from the polymerization reactor is cooled and returned to the reactor for recycling in order to control the polymerization temperature; thereafter, the polyoxymethylene powder is transported by a screw conveyor to undergo stabilization treatment. This technology has low requirements for materials, a simple process, and low corrosivity. The copolymerization technique using triomethylenemethane as the polymerization monomer accounts for 80% of the world’s polyoxymethylene production capacity. In the technology for producing trioxane, the sulfuric acid catalysis method and the solid acid catalysis method currently coexist. The production of 70% concentrated formaldehyde through the oxidation of methylal, developed by Asahi Kasei, represents a significant improvement in the copolymerization process; it eliminates the need for formaldehyde concentration and the recovery of diluted formaldehyde, thereby **reducing energy consumption and costs**. In terms of stabilization technologies, melt processes and liquid-phase hydrolysis processes coexist currently, with the latter holding development potential. Polyoxymethylene is a versatile general-purpose thermoplastic engineering plastic with excellent mechanical properties, electrical properties, wear resistance, dimensional stability, chemical resistance, fatigue resistance, and self-lubricating characteristics. It is an ideal engineering plastic for replacing metals, especially non-ferrous metals such as copper, aluminum, and zinc, as well as their alloys. It can be processed using injection molding, blow molding, extrusion molding, and rotational casting methods. It is widely used in fields such as electronics and electrical engineering, automotive industry, light industry, machinery, chemicals, and building materials. It can be used to manufacture gear drives, pumps, conveyors, bathroom fittings, hand tools, audio and video cassette tapes, toys, construction materials, and medical measuring devices.

Our company’s downstream product is polyoxymethylene; it has not been put into production so far due to inadequate technology in China, as this technology is largely under foreign control. Now we are about to adopt the technology from Poland – 4W is quite good, but risks still exist. Although there are also polyoxymethylene production facilities in China, and they are of a considerable scale, from what I’ve heard from several colleagues, the quality of the products is not very good. Even though the market demand is high, it’s still not possible to get a good price for these products, which is frustrating

Polyoxymethylene is a great project. A type of engineering plastic; there is a large demand for its products in China, the country relies heavily on imports for them, so its prospects are promising. Yuntianhua is quite good; it’s the leader in polyoxymethylene production in China

Two characters were typed incorrectly; it should be “supply-demand gap”. Is the person on the 9th floor from United Chemicals?