Net structure and a manufacturing method therefor

Abstract

To provide a net structure in which the compressive hardness can be changed without impairing the texture and increasing the product weight, and in which the boundary of the compressive hardness is clear. A net structure having a three-dimensional random loop junction structure composed of thermoplastic elastomer continuous filaments, the net structure including portions differing in terms of compressive hardness by 5% or more zonally, a difference in apparent density between the portions differing in terms of compressive hardness being 0.005 g/cm3 or less.

1 . A net structure having a three-dimensional random loop junction structure composed of thermoplastic elastomer continuous filaments, the net structure including portions differing in terms of compressive hardness by 5% or more zonally, a difference in apparent density between the portions differing in terms of compressive hardness being 0.005 g/cm 3  or less. 
     
     
         2 . The net structure according to  claim 1 , wherein the difference in apparent density between the portions differing in terms of compressive hardness is 0.003 g/cm 3  or less. 
     
     
         3 . The net structure according to  claim 1 , wherein the thermoplastic elastomer is a polyester-based thermoplastic elastomer. 
     
     
         4 . The net structure according to  claim 1 , wherein the number of junction points (pieces/g) differs by 7% or more between the portions differing in terms of compressive hardness. 
     
     
         5 . The net structure according to  claim 1 , wherein the portions differing in terms of compressive hardness have a difference in fiber diameter of 10% or less. 
     
     
         6 . The net structure according to  claim 1 , wherein in a melting curve measured with a differential scanning calorimeter (DSC), an endothermic peak top temperature appearing at a melting point or lower differs by 1° C. or more between the portions differing in terms of compressive hardness of the net structure. 
     
     
         7 . The net structure according to  claim 6 , wherein in a melting curve measured with a differential scanning calorimeter (DSC), an endothermic peak top temperature appearing at a melting point or lower differs by 2° C. or more between the portions differing in terms of compressive hardness of the net structure. 
     
     
         8 . A method for manufacturing a net structure, comprising:
 an extruding step of supplying a dried thermoplastic elastomer to an extruder from a hopper, measuring a certain amount of a melt-extruded thermoplastic resin with a gear pump, then supplying the thermoplastic resin to a nozzle having a plurality of orifices, and ejecting the thermoplastic resin downward to make the thermoplastic resin naturally drop; and a cooling and forming step of sandwiching ejected filaments in a molten state by a pair of take-off conveyers disposed on cooling water in a water tank, retaining the filaments to form loops, conveying the formed loops into the water tank while the loops come into contact with each other, and cooling the loops with the cooling water to form a random three-dimensional form, wherein   a cooling speed of the thermoplastic resin at the time of passing through conveyance equipment in the water tank is partially varied.   
     
     
         9 . The method for manufacturing a net structure according to  claim 8 , wherein a speed of the cooling water is partially varied. 
     
     
         10 . The method for manufacturing a net structure according to  claim 8 , wherein
 a water ejection device that ejects cooling water is provided, and   an ejection position of the cooling water by the water ejection device is below a water surface of the water tank.