Hoechst Aktiengesellschaft

Alwin Heller

Karlheinz Burg

Gunter Sextro

Helmut Schlaf

Hans-Dieter Sabel

Hans Joachim Leugering

Oxymethylene polymers (POM) are obtained in a granular form, by cooling a POM solution or dispersion, whose temperature is above the sintering temperature of the POM, to a temperature slightly below the sintering temperature of the POM, and extracting from the suspension obtained only those POM particles which show a grain diameter of more than 70 .mu.m. As solvent or dispersing agent as well as precipitating and cooling agent there is used a mixture of methanol and water with a methanol content of at least 75% by weight. The POM obtained is suitable as engineering plastic material for the manufacture of shaped articles having improved mechanical properties.

Process for the preparation of granular oxymethylene polymers having

Oxymethylene polymers are obtained in a granular form by cooling a solution or dispersion of an oxymethylene polymer, the temperature of which solution or dispersion is above the sintering temperature of the oxymethylene polymer, to a temperature just below the sintering temperature of the oxymethylene polymer. As dissolving or dispersing agent as well as precipitating and cooling agent there is used a mixture of methanol and water having a methanol content of at least 75% by weight. The oxymethylene polymer obtained is suitable as engineering plastic for preparing moulded articles.

Process for preparing oxymethylene polymers in a granular form

Granular oxymethylene polymers are prepared by cooling a solution or dispersion of an oxymethylene polymer, the temperature of the said solution or dispersion being above the sintering temperature of the oxymethylene polymer, to a temperature just below the said sintering temperature. As dissolving or dispersing agent there is used a mixture of methanol and water. The cooling of the said solution or dispersion is effected in two stages while using a liquid cooling agent or a cooling device. After precipitation the coarse-granular polymer is separated from the fine-granular portion. It is suitable as engineering plastic for preparing molded articles.

Process for the manufacture of coarse-granular oxymethylene polymers

Oxymethylene polymers (POM) are obtained in granular form by cooling a POM solution or dispersion having a temperature above the sintering temperature of the POM in two stages to a temperature just below the said sintering temperature. The solvent or dispersion agent used is a mixture of methanol and water and the cooling agent is a methanol/water mixture which may contain POM suspended therein. The granular POM obtained is suitable as technical material for making shaped articles.

Growing community of inventors

Erzhausen, Germany

Alwin Heller