PEP Review 89-2-3
Acetal Copolymers by an Asahi Chemical Process
Asahi Chemical has developed and commercialized a process for acetal copolymer production. Its main features are the production of a highly concentrated aqueous formaldehyde solution from methylal oxidation, the production and recovery of highly purified trioxane from the concentrated aqueous formaldehyde solution, the recovery of highly purified trioxane from the catalyst deactivating wash water, and the use of methylal as both chain transfer and end-capping agent in the copolymerization.
Our preliminary evaluation indicates that compared to the cost estimates based on a Celanese patent and presented in the PEP Yearbook 1989 (page l-393), the novel Asahi Chemical process requires approximately the same battery limits investment but slightly lower off-sites investment. Its production cost and product value are lower than those in the Yearbook, primarily because of the lower raw material costs and utilities costs. However, the Yearbook recipe not only calls for higher raw materials consumption but it also uses a much higher ethylene oxide-to-methanol (weight) ratio, and ethylene oxide is more expensive than methanol.