Method for producing water-absorbent polymers

• Main Authors: VAN ESBROECK, DOMINICUS, WEISMANTEL, MATTHIAS, BRUHNS, STEFAN
• Format: Patent
• Language: English; French; German
• Published: 23.03.2011
• Subjects: AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F,C08G; BLASTING; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS, ORSURGICAL ARTICLES; CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOIDCHEMISTRY; CHEMISTRY; COMPOSITIONS BASED THEREON; DISINFECTION, STERILISATION, OR DEODORISATION OF AIR; DRYING; DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM; GENERAL PROCESSES OF COMPOUNDING; HEATING; HUMAN NECESSITIES; HYGIENE; LIGHTING; MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVINGCARBON-TO-CARBON UNSATURATED BONDS; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS, OR SURGICALARTICLES; MECHANICAL ENGINEERING; MEDICAL OR VETERINARY SCIENCE; METALLURGY; METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS INGENERAL; ORGANIC MACROMOLECULAR COMPOUNDS; PERFORMING OPERATIONS; PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL; THEIR PREPARATION OR CHEMICAL WORKING-UP; THEIR RELEVANT APPARATUS; TRANSPORTING; WEAPONS; WORKING-UP

Preparation of water-absorbing polymers (A) with drying quality index comprises polymerizing a monomer solution and drying the obtained hydrogel agent in hot-gas flow, where the drying process takes place in at least two temperature zones, when the flow of the hydrogel in the gas flow is: downwards in the front side of the volume drier, and upwards against the rear side of the drier; where the amount of water in the hydrogel is 15-45 wt.%, the hydrogel layer in the volume drier flows at least partially against down wards, and the speed of the gas is 5-30%. Preparation of water-absorbing polymers (A) with drying quality index comprises polymerizing a monomer solution and drying the obtained hydrogel agent in hot-gas flow, where the drying process takes place in at least two temperature zones, when the gas inlet temperature (T n) is not equal to T n + a; and flow of the hydrogel in the gas flow is: downwards in the front side of the volume drier, and upwards against the rear side of the drier; where the amount of water in the hydrogel is 15-45 wt.%, the hydrogel layer in the volume drier flows at least partially against down wards, and the speed of the gas is 5-30%. n : index; and a : greater than 0. An independent claim is included for a device for drying (A) comprising a gas permeable conveyer belt (which is streamed by a preheated gas), where the gas inlet temperature is adjusted such that it can come form at least two temperature zones. Die Erfindung betrifft ein Verfahren zur Herstellung wasserabsorbierender Polymere durch Polymerisation einer Monomerlösung und Trocknung des erhaltenen Hydrogels mittels eines erwärmten Gasstromes, wobei - die Trocknung in mindestens zwei Temperaturzonen durchgeführt wird wobei die Gaseingangstemperaturen die Bedingung T n ungleich T n+a erfüllen und die Gaseingangstemperatur T n+a mindestens 150°C beträgt, wobei die Indizes n und a jeweils eine ganze Zahl größer 0 bedeuten und - optional der Gasstrom das Hydrogel im vorderen Abschnitt eines Bandtrockners von unten und im hinteren Abschnitt des Bandtrockners von oben anströmt, wobei die Strömungsumkehr bei einem Wassergehalt des Hydrogels von 15 bis 45 Gew.-% stattfindet, und - optional die Hydrogelschicht in einem Bandtrockner zumindest teilweise von unten angeströmt wird, wobei die Gasgeschwindigkeit von 5 bis 30% der Gasgeschwindigkeit beträgt, die notwendig ist um das Hydrogel vom Band zu lösen.