Abstract: The invention relates to a process for preparation of polymer blends comprising at least one polyoxymethylene and at least one thermoplastic elastomer, where the thermoplastic elastomer is micropelletized by a pelletizing process and the pellets obtained in a) are dispersed in the polyoxymethylene matrix via melting of the components and mixing of these at low shear forces, and also to the use of micropelletized thermoplastic elastomers for preparation of polyoxymethylenes with low formaldehyde emission.

Abstract: Multiblock copolymers are described and contain the structural unit of formula I -A-O—R1—O—CO—(R2—CO—)m—X-D-X—(CO—R2)m—CO—X—??(I), where A is a radical derived from a homo- or copolyoxymethylene, R1 is an alkylene radical-having at least two carbon atoms or a cycloalkylene radical, R2 is a direct carbon-carbon bond, or an alkylene, cycloalkylene, arylene, or aralkylene radical, X is selected from —O—, —S—, or —NH—, D is a divalent radical B which is a radical of a hydroxy-terminated, mercaptan-terminated, or amino-terminated polymer which derives from polyalkylene glycols, polyvinyl ethers, polyvinyl ether-alkene copolymers, polyvinyl esters, polyvinyl ester-alkene copolymers, polyvinyl alcohols, polyvinyl alcohol-alkene copolymers, polyvinylaromatics, polyacrylates, polymethacrylates, polyacetals, polycarbonates, polyesters, polyamides, polyimines, polyetherester elastomers, polyetheramide elastomers, polyalkadienes, polyurethanes, polyureas, polysiloxanes, or a triblock copolymer radical -PAO-B-PAO-, wh

Abstract: A process for preparing acetals from aldehydes and alcohols is carried out by generating a reaction/distillation zone charged with an acidic fixed bed catalyst in a distillation column, feeding the aldehyde and the alcohol to the reaction/distillatlon zone and at least partly converting them to the acetal, heating the column bottom disposed below the reaction/distillation zone in order to at least partly evaporate the bottom's mixture and to establish a defined temperature in the reaction/distillation zone, feeding an extractant into a rectifying section of the column, disposed above the reaction/distillation zone and condensing a product having more than 90% by weight of acetal at the top of the column.

Abstract: Colored molding compositions made from polyacetal copolymer, where the polyacetal copolymer essentially consists of oxymethylene units and oxyethylene units, and a strong protonic acid was used as initiator during preparation of the polyacetal copolymer, have lower formaldehyde emission than that from a comparable molding composition for which the polyacetal copolymer was prepared using a Lewis acid as initiator. The formaldehyde emission is generally less than 20 mg/kg, preferably less than 10 mg/kg.

Abstract: Copolymers are described containing blocks of the structural repeat units of the formula I and blocks containing structural units of the formula II [—O—CH2—]x, ??(I) [—O—R1—], ??(II) where R1 is a divalent radical derived from a hydroxy-terminated aliphatic or cycloaliphatic oligomer or polymer which, where appropriate, has ether groups and/or carbonyloxy groups in the chain, and x is a whole number, at least 10. The copolymers may be used for producing moldings.

Abstract: Process for removing methanol from formaldehyde-containing solutions. The present invention relates to a process for removing methanol from formaldehyde-containing solutions, with methanol being converted into formaldehyde dimethyl acetal by reactive distillation in the presence of an acidic fixed-bed catalyst, and the resultant mixture comprising methanol, formaldehyde dimethyl acetal and possibly other impurities being distilled off.

Abstract: Copolymers are described containing blocks of the structural repeat units of the formula I and blocks containing structural units of the formula II [—O—CH2—]x,??(I) [—O—R1—],??(II) where R1 is a divalent radical derived from a hydroxy-terminated aliphatic or cycloaliphatic oligomer or polymer which, where appropriate, has ether groups and/or carbonyloxy groups in the chain, and x is a whole number, at least 10. The copolymers may be used for producing moldings.

Abstract: Colorant concentrates made from free-flowing polyoxymethylene copolymer as carrier, 15-80% by weight of colorant, 2-15% by weight of nitrogen-containing stabilizer and 0-15% by weight of dispersion aid for coloring pellets or molding compositions made from polyoxymethylene (POM) and for producing colored injection moldings or colored POM extrudates. The products produced with this colorant preparation are particularly stable during processing and have very low formaldehyde emissions.

Abstract: A process for the preparation of polyoxymethylene copolymers, wherein 1,3,5-trioxane is polymerized with generally known comonomers in the presence of a strong protonic acid initiator and in the presence of a formaldehyde dialkyl acetal, and wherein the initiator is dissolved in the formaldehyde dialkyl acetal before admixing to the trioxane and the comonomers.