Process for the manufacture of methyl cellulose ether
View Patent ↗A water-soluble methyl cellulose ether, having a flocculation point below 100° C., is manufactured by reacting methyl chloride and a cellulose activated by mercerizing the cellulose with aqueous alkali in the presence of a C 2 -C 3 alkyl chloride as a reaction medium at a temperature from 65° C. to 90° C. and at a pressure from 3 to 15 bar. The weight ratio between the cellulose and the C 2 -C 3 alkyl chloride is normally from 1:1 to 1:5. The use of the reaction medium makes it possible to produce at a low pressure methyl cellulose ether at a good rate.
1. A process for the manufacture of a water-soluble methyl cellulose ether, having a flocculation point below 100° C. which comprises reacting methyl chloride and a cellulose activated by mercerising the cellulose with aqueous alkali, wherein the reaction is performed in the presence of a C 2 -C 3 alkyl chloride as a reaction medium at a reaction temperature from 65° C. to 90° C. and at a pressure from 3 to 15 bar.
2. The process of claim 1 , wherein the weight ratio between the cellulose and the C 2 -C 3 alkyl chloride is from 1:1 to 1:5.
3. The process of claim 1 , wherein the weight ratio between the cellulose and the C 2 -C 3 alkyl chloride is from 1:1.3 to 1:2.5 and the pressure below 10 bar.
4. The process of claim 1 wherein the C 2 -C 3 alkyl chloride is added to the cellulose before the activation of the cellulose and/or during the mercerisation of the cellulose.
5. The process of claim 1 wherein a portion of the methyl chloride is added while the temperature is raised to the reaction temperature, whereupon the remaining methyl chloride is added in such a rate that the temperature and the reactor pressure is maintained.
6. The process of claim 1 wherein the methyl chloride is added in an amount from 0.9 to 4.9 moles per mole saccharide unit of the cellulose.
7. The process of claim 1 wherein the activated cellulose is reacted with ethylene oxide and/or propylene oxide at a temperature from 50° C. to 80° C. and 60° C. to 80° C. respectively before the addition of methyl chloride and/or together with methyl chloride.
8. The process of claim 1 of wherein the activated cellulose is also reacted with reactants chosen from the group consisting ethyl chloride; propyl chloride; butylene oxide; 2-chloro acetic acid; RO(C 2 H 4 O) n CH 2 CH(OH)CH 2 Cl and
where R is a hydrocarbon having 4 to 22 carbon atoms and n is a number from 0 to 7; 3-chloro-2-hydroxypropyl trialkylammonium chloride and glycidyl trialkylammonium chloride where alkyl is an alkyl with 1 to 22 carbon atoms with the proviso that at most one of the alkyl groups have more than 2 carbon atoms; and the corresponding primary, secondary or tertiary ammonium and amine compounds.
9. The process of claim 1 wherein methyl chloride and the other etherifying reactants are added in such amounts that a methyl cellulose ether is obtained having a DS methyl from 0.6 to 2.5, a DS ethyl from 0 to 0.8, a DS propyl from 0 to 0.2, a DS carboxymethyl from 0 to 0.2, a DS ammonium containing substituents from 0 to 1.0, DS RO(C2H40)n CH2CH(OH)CH2 , where R and n have the meanings mentioned above from 0 to 0.3, a MS hydroxyethyl from 0 to 1.6, a MS hydroxypropyl from 0 to 0.9 and a MS hydroxybutyl from 0 to 0.3.
10. The process of claim 9 , wherein the methyl cellulose produced is a methyl cellulose having a DS methyl from 1.0 to 2.0; a methyl hydroxyethyl cellulose having a DS methyl from 1.2 to 2.0 and a MS hydroxyethyl from 0.05 to 1.2; a methyl hydroxypropyl cellulose having a DS methyl from 1.0 to 2.0 and a MS hydroxypropyl from 0.1 to 1.0; a methyl ethyl hydroxyethyl cellulose having a DS methyl from 1.0 to 2.0, a DS ethyl from 0.1 to 0.6 and a MS hydroxyethyl from 0.05 to 1.2; and a methyl carboxymethyl cellulose having a DS methyl from 1.0 to 2.0 and a DS carboxymethyl from 0.05 to 0.2.