Method of treating cellulose fibres with chlorine dioxide and an alkyl cellulose derivative
View Patent ↗The present invention relates to methods of modifying cellulose fibers and of producing paper which methods include providing a pulp suspension of cellulose fibers and adding a cellulose derivative during the bleaching of the cellulose fibers in an acidic bleaching stage.
1. A method of modifying cellulose fibers comprising providing a pulp suspension of cellulose fibers, subjecting said cellulose fibers to bleaching and adding an alkyl cellulose derivative in an amount from about 0.5 to about 20 kg/t of dry cellulose fibers during said bleaching of said cellulose fibers to at least one acidic chlorine dioxide bleaching stage.
2. A method according to claim 1 , wherein the alkyl cellulose derivative is added to a final acidic chlorine dioxide bleaching stage.
3. A method according to claim 1 , wherein the alkyl cellulose derivative is a carboxyalkyl cellulose.
4. A method according to claim 1 , wherein the alkyl cellulose derivative is carboxymethyl cellulose.
5. A method according to claim 1 , wherein the dry content of the cellulose fibers in the pulp suspension is from about 1 to about 50 wt %.
6. A method according to claim 1 , wherein a wet strength agent is subsequently added.
7. A method according to claim 1 , wherein a dry strength agent is subsequently added.
8. A method according to claim 1 , wherein the bleaching stage is a final bleaching stage performed at a pH from about 2 to about 4.
9. A method of producing paper comprising dewatering on a wire a pulp furnish comprising modified cellulose fibers and wet strength agent and forming a paper of said dewatered pulp furnish which modified cellulose fibers have been obtained by providing a pulp suspension of cellulose fibers, subjecting said cellulose fibers to bleaching and adding an alkyl cellulose derivative in an amount from about 0.5 to about 20 kg/t dry cellulose fibers during said bleaching of said cellulose fibers to a final acidic chlorine dioxide stage, wherein the pH during said bleaching is 2 to 4.
10. A method according to claim 9 , wherein the alkyl cellulose derivative is a carboxyalkyl cellulose.
11. A method according to claim 9 , wherein the alkyl cellulose derivative is carboxymethyl cellulose.
12. A method according to claim 9 , wherein a dry strength agent is subsequently added.
13. A method of producing paper comprising providing a pulp suspension of a bleached pulp obtained by providing a pulp suspension of cellulose fibers comprising providing a pulp suspension of cellulose fibers, subjecting said cellulose fibers to bleaching and adding an alkyl cellulose derivative in an amount from about 0.5 to about 20 kg/t dry cellulose fibers during said bleaching of said cellulose fibers to at least one acidic chlorine dioxide bleaching stage, dewatering said bleached pulp suspension on a wire and forming a paper of the dewatered pulp.