This application relates to the reduction in the degree of polymerization (DP) of cellulose with enzymes to provide a pulp with acceptable metals levels suitable for lyocell manufacture.
FIG. 1 is a 1 K magnification of a lyocell fiber spun from the low DP pulp in this application.
In order to obtain a higher throughput in lyocell production (higher concentration of pulp in the solvent NMMO or higher throughput per hole per minute) it is necessary to use a lower DP pulp than currently used. Use of enzymes at various stages of the bleaching process can yield lower DP pulps which are suitable for lyocell.
Enzymes are used in the treatment of cellulosic pulp to improve the bleaching and to reduce the DP of the pulp. One use of enzymes is to control the viscosity of the pulp during the bleach treatment. A low uniform viscosity is needed for dissolving and non dissolving pulps useful for rayon or lyocell production. Enzymes may be used to control this viscosity.
