Resin composition for monofilaments, use thereof, and method for producing monofilament

Abstract

A resin composition for monofilaments contains a poly(3-hydroxyalkanoate)-based resin component. The resin composition has a melting point peak temperature of 140° C. or higher and a crystal melting enthalpy of 65 J/g or less as calculated from all melting peaks in differential scanning calorimetry. The monofilament containing the resin composition has high strength and elongation. A method for producing the monofilament containing the resin composition contains, in the stated order, (i) discharging the resin composition in a molten state from a spinning nozzle, and then cooling thereby forming a raw yarn and (ii) stretching the raw yarn in at least one direction.

1 . A resin composition for monofilaments comprising a poly(3-hydroxyalkanoate)-based resin component, wherein the resin composition has:
 a melting point peak temperature of 140° C. or higher; and   a crystal melting enthalpy of 65 J/g or less as calculated from all melting peaks in differential scanning calorimetry.   
     
     
         2 . The resin composition for monofilaments according to  claim 1 , wherein the poly(3-hydroxyalkanoate)-based resin component comprises two or more copolymers of a 3-hydroxybutyrate unit and another hydroxyalkanoate unit, wherein the two or more copolymers have a different type of the other hydroxyalkanoate unit and/or a different content ratio of the other hydroxyalkanoate unit from each other. 
     
     
         3 . The resin composition for monofilaments according to  claim 1 , wherein the poly(3-hydroxyalkanoate)-based resin component comprises:
 a copolymer (A) of a 3-hydroxybutyrate unit and 6 mol % or less of another hydroxyalkanoate unit; and   a copolymer (B) of a 3-hydroxybutyrate unit and 24 mol % or more of another hydroxyalkanoate unit.   
     
     
         4 . The resin composition for monofilaments according to  claim 3 , wherein a content ratio of the copolymer (B) to the poly(3-hydroxyalkanoate)-based resin component is 20 wt % or more and 50 wt % or less. 
     
     
         5 . The resin composition for monofilaments according to  claim 2 , wherein the other hydroxyalkanoate unit is a 3-hydroxyhexanoate unit. 
     
     
         6 . A monofilament comprising the resin composition for monofilaments according to  claim 1 . 
     
     
         7 . The monofilament according to  claim 6 , having a fineness of 15 to 5,000 dtex, a tensile strength of 0.4 to 6 cN/dtex, and a tensile elongation of 500 or more. 
     
     
         8 . The monofilament according to  claim 7 , wherein a fineness is in a range of 1,000 to 5,000 dtex. 
     
     
         9 . Artificial turf comprising a turf yarn implanted in a base fabric, wherein the turf yarn comprises the monofilament according to  claim 6 . 
     
     
         10 . A method for producing a monofilament containing the resin composition for monofilaments according to  claim 1 , comprising the following steps (i) and (ii) in a stated order:
 (i) discharging the resin composition in a molten state from a spinning nozzle, and then cooling thereby forming a raw yarn; and   (ii) stretching the raw yarn in at least one direction.