Polyurethane type elastic fiber, and a process of preparing for the same

Abstract

Disclosed a polyurethane elastic fiber and a method of producing the polyurethane elastic fiber. The method of producing the polyurethane elastic fiber is characterized in that polyol with high molecular weight and diisocyanate with excessive amount are mixed in a condition of a designated shear rate and prepolymerized to produce a prepolymer, the prepolymer is reacted with the chain extender and the chain terminator to produce a polymer, and an additive is added to the polymer and the final polymer is spun. The method of producing the polyurethane elastic fiber according to the present invention improves the stability of the polymer, has an excellent spinnability even in high-speed spinning, and remarkably reduces the generation of wave yarns. The polyurethane elastic fiber of the present invention is excellent in heat resistance, thermosetting efficiency and coherence strength between the monofilaments.

What is claimed is:  
     
         1 . A method of producing a polyurethane elastic fiber, characterized in that a prepolymer is produced using a continuous polymerizing tube in a cylinder pipe comprising a static mixer, a heat raiser, a reactor, and a cooler, as follows, and the prepolymer is reacted with a chain extender/a chain terminator to produce a polymer, and an additive is then added to the polymer.  
       —As Follows— 
       [A Process of Producing the Prepolymer]
 (i) mixing polyol with high molecular weight and diisocyanate with excessive amount within the static mixer with the shear rate of more than 20 sec −1  without the inner mixing element,  
 (ii) first-reacting polyol with high molecular weight and diisocyanate with excessive amount within the heat raiser with the shear rate of more than 3 sec −1  without the inner mixing element, and  
 (iii) second-reacting the first-reacted compound within the reactor with the shear rate of more than 0.1 sec −1  without the inner mixing element, thereby preparing a first prepolymer.  
 
     
     
         2 . The method of producing the polyurethane elastic fiber as set forth in  claim 1 , wherein the temperature of the static mixer is 43˜44° C.  
     
     
         3 . The method of producing the polyurethane elastic fiber as set forth in  claim 1 , wherein the temperature of the heat raiser is less than 90° C.  
     
     
         4 . The method of producing the polyurethane elastic fiber as set forth in  claim 1 , wherein the temperature of the reactor is 80˜90° C.  
     
     
         5 . The method of producing the polyurethane elastic fiber as set forth in  claim 1 , wherein in the chain extending/chain terminating reaction, the chain extender of 96˜98.5 equivalent % and the chain terminator of 4.5˜7.0 equivalent % are added.  
     
     
         6 . The method of producing the polyurethane elastic fiber as set forth in  claim 1 , wherein the polymerized polyurethane polymer and the additive are mixed within the static mixer with the shear rate of more than 0.13 sec −1  without the inner mixing element.  
     
     
         7 . The method of producing the polyurethane elastic fiber as set forth in  claim 1 , wherein the chain extender is a N,N′-dimethylacetamide solution comprising ethylene diamine of 60˜75 mol %, 1,2-diaminopropane of 24.9˜39 mol %, and diethylenetriamine of 0.1˜1 mol %.  
     
     
         8 . The method of producing the polyurethane elastic fiber as set forth in  claim 1 , wherein the additive comprises a triamine group compound.  
     
     
         9 . The method of producing the polyurethane elastic fiber as set forth in  claim 8 , wherein the content of the triamine group compound is 0.1˜0.3 weight % to solids of the polymer.  
     
     
         10 . The method of producing the polyurethane elastic fiber as set forth in  claim 8 , wherein the triamine group compound is diethylenetriamine.  
     
     
         11 . A polyurethane elastic fiber characterized in that coherence strength between monofilaments is more than 145 mgf.