Abstract: The present invention relates to isocyanate-terminated prepolymers based on polyoxymethylene-polyoxyalkylene block copolymers, to a process for their preparation, and to the use of these isocyanate-terminated prepolymers as isocyanate components in 1- and 2-component systems for coatings, adhesives and sealants.

Abstract: A method for producing a prepolymer for the production of an integral polyurethane foam is provided. The prepolymer is or can be obtained by reaction of a composition that contains the following components: component A containing a polyoxymethylene-polyoxyalkylene block copolymer having a hydroxyl number of 20 mg KOH/g to 200 mg KOH/g as component Al, component B containing di- and/or polyisocyanates with an NCO content of 15 to 45 wt.-% relative to component B, 0.04 to 1.0 wt.-%, relative to the composition, a proton acid as component C, and optionally a component D that contains auxiliary agents, at a characteristic number of 450 to 850. The invention further relates to the prepolymer obtained by the method, to an integral polyurethane foam based on the prepolymer, and to the use thereof.

Abstract: A process for producing polyoxymethylene polymers comprises the reaction of aqueous formaldehyde solution with an aqueous solution of a base, wherein A) a starter solution comprising formaldehyde is initially charged and B) an aqueous formaldehyde solution and a base are added to the starter solution to obtain a reaction mixture. The starter solution in step A) has a temperature of ?40° C. to ?46° C. and the additions of the solutions in step B) are performed at a temperature of the reaction mixture of ?40° C. to ?46° C. The base is an alkali metal hydroxide and/or an alkaline earth metal hydroxide and the molar ratio of formaldehyde to base is ?55:1 to ?90:1 based on the total amounts of formaldehyde and base employed in the process. The base in step B) is added in aqueous solution.