Process for Dyeing Ramie Sliver and Method for Preparing Yarn

Abstract

A process for dyeing ramie sliver, comprising: 1.) pretreatment: cooking the ramie sliver for 8-12 minutes in a cooking reagent in a bath ratio of 1:4-10, the cooking reagent is a 1-3 g/L aqueous solution of a penetrating agent; and 2.) dyeing: dyeing the cooked ramie sliver in an active dye in a bath ratio of 1:4-10. Also disclosed is a method for preparing ramie yarn. The ramie sliver dyed according to the present invention improves the properties of ramie fibers, such that the ramie fibers are less likely to break; and the ramie fibers are less likely to harden, avoiding poor drawing, needle breakage and missing stitches during carding and coalescing in post-procedures, thus achieving the purpose of smooth yarn spinning. Also disclosed is a method for preparing ramie colored-spun yarn.

1 . A ramie sliver dyeing process, comprising
 (1) pretreatment: steaming ramie slivers for 8-12 min at a bath ratio of 1:4-10 with a 1-3 g/L aqueous solution of a penetrant as a steaming agent;   (2) dyeing: dyeing the steamed ramie slivers in an active dye at a bath ratio of 1:4-10.   
     
     
         2 . The ramie sliver dyeing process according to  claim 1 , characterized in step (2) dyeing comprising the following procedures: adding ramie slivers to a dissolved active dye at atmospheric temperature, stirring for 5-10 min; adding a salt solution, increasing temperature to 60° C.-70° C., running for 5-8 min, adding sodium carbonate solution, and running for 40-60 min while holding the temperature; taking the ramie slivers out, and sequentially performing washing with clear water, neutralizing with diluted acid, soaping, and washing with cold water. 
     
     
         3 . The ramie sliver dyeing process according to  claim 1  characterized in further comprising (3) post-treatment: subjecting the dyed ramie slivers to color fixing and oiling,
 said color fixing is carried out by immersing ramie slivers in an aqueous solution containing 2-4% (o.w.f) of a color fixing agent and 2-5% (o.w.f) of a softener at 35° C.-50° C. for 10-20 min, 
 said oiling is carried out by immersing the color-fixed ramie slivers in an aqueous solution containing 2-3 g/L of an oil agent at 60° C.-70° C. for 20-30 min. 
 
     
     
         4 . The ramie sliver dyeing process according to  claim 2 , characterized in that said soaping is carried out by washing the ramie slivers in a 1-2 g/L of detergent at 90° C.-100° C. for 10-15 min. 
     
     
         5 . The dyeing process according to  claim 1 , characterized in that the ramie slivers in step (1) are set to have a coiler shape. 
     
     
         6 . A method for preparing ramie colored-spun yarn, comprising the following steps:
 (1) preparing ramie fibers into ramie balls having a coiler shape;   (2) steaming ramie balls for 8-12 min at a bath ratio of 1:4-10 with a 1-3 g/L aqueous solution of a penetrant as a steaming agent;   (3) dyeing the ramie balls steamed in step (2) in an active dye at a bath ratio of 1:4-10;   (4) subjecting the ramie slivers dyed in step (3) to color fixing and oiling;   (5) dewatering and drying the ramie slivers from step (4); standing for more than 24 h;   (6) coalescing, drawing and combing the ramie slivers after standing in step (5); coalescing and drawing the combed ramie slivers; and   (7) spinning the ramie slivers' from step (6) into yarns at 20-30° C. and relative humidity of 70-90%.   
     
     
         7 . A method for preparing ramie colored-spun yarn according to  claim 6 , characterized in that the drying in step (5) is required to achieve a moisture regain of 7-10% and an oil content of 0.5-1.5%. 
     
     
         8 . A method for preparing ramie colored-spun yarn according to  claim 6 , characterized in that the ramie sliver used for spinning yarn in step (7) has at least one color. 
     
     
         9 . The ramie sliver dyeing process according to  claim 2 , characterized in further comprising (3) post-treatment: subjecting the dyed ramie slivers to color fixing and oiling,
 said color fixing is carried out by immersing ramie slivers in an aqueous solution containing 2-4% (o.w.f) of a color fixing agent and 2-5% (o.w.f) of a softener at 35° C.-50° C. for 10-20 min,   said oiling is carried out by immersing the color-fixed ramie slivers in an aqueous solution containing 2-3 g/L of an oil agent at 60° C.-70° C. for 20-30 min.