Lyocell fiber and manufacturing method therefor

Abstract

The present invention relates to a lyocell fiber, and more specifically to a lyocell fiber, wherein the cross-sectional shape of a monofilament contained in the lyocell fiber is controlled to thus increase the specific surface area of the fiber, thereby exhibiting properties equal or superior to those of conventional lyocell fibers, even when used in a small amount.

1 . A lyocell fiber having a multi-lobal cross-section, comprising a lyocell multifilament manufactured by spinning a lyocell spinning dope including a cellulose pulp and an ionic solvent,
 the multifilament comprising a monofilament having a multi-lobal cross-section,   the multi-lobal cross-section of the monofilament including a plurality of projections, and   the plurality of projections coming into contact with a first virtual circle and a second virtual circle included in the first virtual circle, being integrally formed with the second virtual circle serving as a center, and coming into contact with the first virtual circle at ends thereof.   
     
     
         2 . The lyocell fiber of  claim 1 , wherein the multi-lobal cross-section has a multi-lobal ratio of 1.5 to 10, as defined in Equation 1 below:
   Multi-lobal ratio= r 1/ r 2  <Equation 1>
   wherein r1 is a radius of the first virtual circle and r2 is a radius of the second virtual circle.   
     
     
         3 . The lyocell fiber of  claim 2 , wherein the lyocell fiber has a fineness of 1 to 30 denier, the radius of the first virtual circle is 4 to 40 μm, and the radius of the second virtual circle is 2 to 14 μm. 
     
     
         4 . The lyocell fiber of  claim 1 , wherein the lyocell fiber has a space occupancy of 200 to 600%, as defined by Equation 2 below:
   Space occupancy=( S 1/ S 2)×100(%)  <Equation 2>
   wherein S1 is an area of the first virtual circle and S2 is a cross-sectional area of the monofilament contained in the lyocell fiber.   
     
     
         5 . The lyocell fiber of  claim 1 , wherein the cellulose pulp contains 85 to 98 wt % of alpha-cellulose. 
     
     
         6 . The lyocell fiber of  claim 1 , wherein the ionic solvent is an aqueous solution including at least one ionic compound selected from the group consisting of dibutyl imidazolium acetate, dipentyl imidazolium acetate, dihexyl imidazolium acetate, dipropyl imidazolium octanoate, dibutyl imidazolium octanoate, 1-ethyl-3-methyl imidazolium heptanoate, 1-ethyl-3-methyl imidazolium octanoate, 1-ethyl-3-methyl imidazolium nonanoate, 1-ethyl-3-methyl imidazolium decanoate, 1-ethyl-3-methyl imidazolium undecanoate, 1-ethyl-3-methyl imidazolium dodecanoate, 1-ethyl-3-methyl imidazolium diethyl phosphate, diethyl imidazolium octanoate, 1-decyl-3-methyl imidazolium acetate, and 1-ethyl-3-methyl imidazolium acetate. 
     
     
         7 . A method of manufacturing a lyocell fiber having a multi-lobal cross-section, comprising the steps of:
 (S1) preparing a lyocell spinning dope including a cellulose pulp and an ionic solvent;   (S2) spinning the spinning dope into a multifilament in a coagulation solution including the ionic solvent through a spinning nozzle and simultaneously coagulating the spun multifilament in the coagulation solution; and   (S3) water-washing the spun and coagulated multifilament,   wherein a lyocell multifilament manufactured through the steps (S1) to (S3) comprises a monofilament having a multi-lobal cross-section, the multi-lobal cross-section of the monofilament includes a plurality of projections, and the plurality of projections comes into contact with a first virtual circle and a second virtual circle included in the first virtual circle, and comes into contact with the first virtual circle at ends thereof.   
     
     
         8 . The method of  claim 7 , wherein the cellulose pulp in the step (S1) contains 85 to 98 wt % of alpha-cellulose. 
     
     
         9 . The method of  claim 7 , wherein the lyocell spinning dope in the step (S1) includes 6 to 25 wt % of the cellulose pulp and 75 to 94 wt % of the ionic solvent. 
     
     
         10 . The method of  claim 7 , wherein the ionic solvent in the step (S1) is an aqueous solution in which a concentration of the ionic compound is 95% or more. 
     
     
         11 . The method of  claim 7 , wherein the ionic solvent contained in the coagulation solution in the step (S2) is an aqueous solution in which a concentration of the ionic compound is 20 to 70%, and a temperature of the coagulation solution is 30 to 80° C. 
     
     
         12 . The method of  claim 10 , wherein the ionic compound is at least one selected from the group consisting of dibutyl imidazolium acetate, dipentyl imidazolium acetate, dihexyl imidazolium acetate, dipropyl imidazolium octanoate, dibutyl imidazolium octanoate, 1-ethyl-3-methyl imidazolium heptanoate, 1-ethyl-3-methyl imidazolium octanoate, 1-ethyl-3-methyl imidazolium nonanoate, 1-ethyl-3-methyl imidazolium decanoate, 1-ethyl-3-methyl imidazolium undecanoate, 1-ethyl-3-methyl imidazolium dodecanoate, 1-ethyl-3-methyl imidazolium diethyl phosphate, diethyl imidazolium octanoate, 1-decyl-3-methyl imidazolium acetate, and 1-ethyl-3-methyl imidazolium acetate. 
     
     
         13 . The method of  claim 7 , wherein the multi-lobal cross-section of the monofilament has a multi-lobal ratio of 1.5 to 10, as defined in Equation 1 below:
   Multi-lobal ratio= r 1/ r 2  <Equation 1>
   wherein r1 is a radius of the first virtual circle and r2 is a radius of the second virtual circle.   
     
     
         14 . The method of  claim 11 , wherein the ionic compound is at least one selected from the group consisting of dibutyl imidazolium acetate, dipentyl imidazolium acetate, dihexyl imidazolium acetate, dipropyl imidazolium octanoate, dibutyl imidazolium octanoate, 1-ethyl-3-methyl imidazolium heptanoate, 1-ethyl-3-methyl imidazolium octanoate, 1-ethyl-3-methyl imidazolium nonanoate, 1-ethyl-3-methyl imidazolium decanoate, 1-ethyl-3-methyl imidazolium undecanoate, 1-ethyl-3-methyl imidazolium dodecanoate, 1-ethyl-3-methyl imidazolium diethyl phosphate, diethyl imidazolium octanoate, 1-decyl-3-methyl imidazolium acetate, and 1-ethyl-3-methyl imidazolium acetate.