Industrial polyoxymethylene

Application Formaldehyde as a liquid solution of 37-52 wt% is primarily used in the production of polyoxymethylene (POM) and hexamethylenetetramine as well as synthetic resins in the wood industry. 

Another monomer that belongs to this group is cyclic trimer of formaldehyde, 1,3,5-trioxane. Cationic polymerization of 1,3,5-trioxane leading to polyoxymethylene (polyformaldehyde, polyacetal) is one of the few industrially important processes in cationic ring-opening polymerization. 

Cyclic acetals polymerize exclusively by cationic mechanism it should be noted, however, that polyoxymethylene may be obtained also by anionic polymerization of formaldehyde. Both processes are used in industry. 

When formaldehyde is heated with concentrated sulphuric acid, it forms the polymer polyoxymethylene, which contains at least 100 monomers. Polyoxymethylene is linear like paraformaldehyde. The main difference between the two of them is the number of monomers in the polymer. When heated, it also decays into formaldehyde. It is widely used in the textile industry. 

Polymerization of 1,3,5-trioxane (TXN) gives linear polyoxymethylene (POM), a homopolymer of formaldehyde 39). This is the only polyacetal made on the technical scale. Two methods are used for the industrial production of stable, high-molecular-weight POMs. This is either the anionic polymerization of formaldehyde or the cationic copolymerization of the cyclic trimer of formaldehyde TXN with ethylene oxide or 1,3-dioxolane (DXL) ... 

There is a demand for more powerful polymers like for example PEEK [103, 107, 111], which enables new application areas in the automobile industry and medical fields, as shown in Fig. 81 and underlines the increasing potential of SLS-technologies. Because of this EOS GmbH recently presented a high temperature system, EOSINT P 800, along with PEEK HP3 for SLS. There is a further interest in qualification of bulk polymers like polypropylene [100]. 3D Systems Inc. recently presented DuraForm PP 100 for SLS. Further more there is an interest in some technical polymers like Polyoxymethylene [112]. 

The five engineering polymer families are polyamides (PA), thermoplastic polyesters (PEST), polycarbonates (PC), polyoxymethylenes (POM), and polyphenylene ethers (PPE). According to a March 2013 Industry Experts report entitled Engineering Plastics - A Global Market, 19.6 Mt of engineering plastics were produced in 2012. In other words, these polymers constitute only about 10 % by volume of all polymers produced. However, due to superior properties, they command a much larger percentage by value of the plastic consumption. 

Polyethylene, LDPE, or polypropylene, PP, were blended with 1-10 wt% polyoxymethylene, POM, for improved melt flow properties, processability, and extrudate appearance A. Rudin, H. P. Schreiber, Canadean Patent 688,416 688,578, 09 June 1964, Appl. 18 May 1963, to Canadian Industries Ltd. 

The blends described in the EDCPB provide a cross section of commercial alloys available in Asia, Europe, and North America. The focus is on blends with the five principal engineering resins polyamides, thermoplastic polyesters, polycarbonates, polyoxymethylenes (acetals), and polyphenylene ethers. There are but few examples of the commodity (and these mainly with polypropylene) as well as with high performance specialty resin blends. This may leave a wrong impression of the global blend industry. 

Besides monomers containing carbon-carbon double bonds, monomers with heteroatoms at the double bond can also be polymerized via an anionic mechanism. The only monomer with some industrial importance is formaldehyde. It is polymerized [180] via its carbon-oxygen double bond to give polyacetal homopolymer or polyoxymethylene [ Eq. (48)]. 

There are several industrial processes for poly-THF and polyoxymethylene. 

G. Sextro, Polyoxymethylenes, in Ullmann s Encyclopedia of Industrial Chemistry, Vol. 28, 6th ed., Wiley-VCH, Weinheim, 2003. 

Currently, there are only two native acetal producers. Shanghai Pacific Chemical Group Corp is the large producer in China with an annual capacity of 2500 tonnes. Jilin Chemical Industrial has an annual capacity of 800 tonnes. Shanghai Pacific Chemical has formed a joint venture with DuPont to produce acetal. The venture will have an annual capacity of 45 000 tonnes. DuPont has also set up a wholly owned plant in Shenzhen to produce acetal. Both Shanghai Pacific Chemical and Jilin Chemical Industrial are planning to increase their polyoxymethylene (POM) capacities to 5000 tonnes per year. After the completion of these new projects, acetal supply will improve dramatically in China. However, demand will continue to outstrip supply as industrial end-use markets rapidly expand. 

The company s current ethylene capacity is 530 000 tonnes a year. Its ABS capacity is 50 000 tonnes per year. It also has a 100 000 tonnes per year LLDPE facility and has recently added another 120 000 tonnes per year PE facility. Its annual output of PVC, PS and PP are 27 000, 8300 and 12 000 tonnes, respectively. Shijinggou Integrated Chemical Plant of Jilin Chemical Industrial Group, an affiliate of the company, is a major polyoxymethylene (POM) producer in China with a POM capacity of 5000 tonnes per year. Other major products include aniline, sulphuric acid, fuming sulphuric acid, hydrochloric acid, concentrated nitric acid, caustic soda, sodium nitrate, sodium nitrite, calcium carbide, sodium bicarbonate, refined aluminium chloride, liquid sulphur dioxide, hydrogen peroxide, sulphur, commercial liquefied chlorine, ammonia,... 

Due to the industrial importance of the process, many semicrystalline polymers have been investigated polyethylene [116-121], isotatic polypropylene [122-127], polybutene-1 [128], polyoxymethylene (or poly acetal) [129-131], polyamide 6 [132], poly(phenylene sulphide) (PPS) [133], and so on. 

Two types of alcohols were investigated bio-methanol and bio-ethanol. Methanol (methyl alcohol) is used as a solvent (soluble in fats, resins and varnishes), also used in the pharmaceutical component of fuel for aircraft (the main component of fuel), explosives (e.g. C4), as fuel in internal combustion engines such as speedway motorbikes, used with caustic solutions or acids to obtain methyl esters, a basic raw material for polyoxymethylene (polyoxymethylene, polyformaldehyde). Ethanol (ethyl alcohol) is widely used in food and pharmaceutical industries (alcoholic fermentation) and cosmetics it is also used as a solvent. Alcohol may also be used to fuel diesel engines if there are good lubrication injector nozzles and the alcohol is mixed with a small (5-20%) amount of oil. 

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