PROCESS TO PREPARE CROSSLINKED CELLULOSE ETHERS, CROSSLINKED CELLULOSE ETHERS OBTAINABLE BY SUCH PROCESS AND THE USE THEREOF

摘要

The invention relates to a dry or slurry process to prepare phosphate-crosslinked cellulose ethers from a cellulose starting material comprising the steps of adding an alkalizing agent to the cellulose starting material to achieve mercerization, adding an ethehfying agent to the reaction mixture to achieve etherification of the cellulose, and adding a crosslinking agent to the reaction mixture to achieve crosslinking of the cellulose, wherein at least part of the alkalizing agent is added to the cellulose starting material before the etherification and/or crosslinking reactions take place to obtain alkalized cellulose; the crosslinking agent and the etherifying agent are added one after the other in random order or simultaneously; the crosslinking agent is an alkali metal thmetaphosphate; and the crosslinking and etherification steps are performed at an elevated temperature. Additionally, the invention relates to crosslinked cellulose ethers obtainable by the above process having a viscosity and/or water absorption capacity higher than their non-crosslinked equivalents and the use thereof.

主权项

1. A dry or slurry process to prepare phosphate-crosslinked cellulose ethers from a cellulose starting material comprising the steps of
adding an alkalizing agent to the cellulose starting material to achieve mercerization, adding an etherifying agent to the reaction mixture to achieve etherification of the cellulose, and adding a crosslinking agent to the reaction mixture to achieve crosslinking of the cellulose, wherein at least part of the alkalizing agent is added to the cellulose starting material before the etherification and/or crosslinking reactions take place to obtain alkalized cellulose; the crosslinking agent and the etherifying agent are added one after the other in random order or simultaneously; the crosslinking agent is an alkali metal trimetaphosphate; and the crosslinking and etherification steps are performed at an elevated temperature of between 20 and 95° C.; wherein the crosslinking step is carried out at an alkaline pH of higher than 7; and wherein the phosphate-crosslinked cellulose ethers prepared by said dry or slurry process are insoluble in water.