Method of treating cellulose fibres with chlorine dioxide and an alkyl cellulose derivative

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.

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.