Polyester composite fiber with excellent heat-shielding property and coloration

Abstract

To provide a polyester composite fiber having a heat-shielding property due to high reflectance in an infrared wavelength range (800 to 3000 nm) easy to be changed into thermal energy, and having color development property comparable to that of conventional polyester fibers. The composite fiber is a core-sheath type composite fiber including a core component and a sheath component of 10:90 to 30:70 (mass ratio). The core component includes a thermoplastic polymer including a sunlight shielding material having an average particle size of 0.5 μm or smaller in 8-70 wt %. The sheath component includes a polyester-type polymer including heat-shielding fine particles in 0.5-10 wt %, the heat-shielding fine particles capable of maintaining color development property and having an average particle size of 0.1 μm or smaller which is smaller than that of the sunlight shielding material.

What is claimed is: 
     
         1 . A core-sheath type composite fiber comprising a core component and a sheath component, wherein
 the core component comprises a thermoplastic polymer including a sunlight shielding material having an average particle size of 0.5 μm or smaller in an amount of 8% by weight to 70% by weight;   the sheath component comprises a polyester-type polymer including heat-shielding fine particles in an amount of 0.5% by weight to 10% by weight, the heat-shielding fine particles being capable of maintaining color development property and having an average particle size of 0.1 μm or smaller which is smaller than that of the sunlight shielding material; and   the mass ratio of the core component to the sheath component is 10:90 to 30:70.   
     
     
         2 . The core-sheath type composite fiber according to  claim 1 , wherein the core component comprises the sunlight shielding material in an amount of more than 20% by weight and 70% by weight or less. 
     
     
         3 . The core-sheath type composite fiber according to  claim 1 , which has an official moisture regain of 0.4% or more as the entire fiber. 
     
     
         4 . The core-sheath type composite fiber according to  claim 1 , wherein the sunlight shielding material comprises at least one member selected from the group consisting of titanium oxide, zinc oxide, and barium sulfate. 
     
     
         5 . The core-sheath type composite fiber according to  claim 1 , wherein the heat-shielding fine particles comprise at least one selected from the group consisting of silicon dioxide and barium sulfate. 
     
     
         6 . The core-sheath type composite fiber according to  claim 1 , wherein the mean particle size of the sunlight shielding material is more than 0.1 μm. 
     
     
         7 . The core-sheath type composite fiber according to  claim 1 , wherein the fiber satisfies the following formula:
     R/r≧ 1.8   
       wherein “R” represents the linear distance between a centroidal point “G” and a point of the fiber circumference at the farthest from the centroidal point “G”, and “r” represents the linear distance between the centroidal point “G” and a point of the core external boundary at the farthest from the centroidal point “G”. 
     
     
         8 . The core-sheath type composite fiber according to  claim 1 , which has an average reflectance of 70% or higher against an infrared ray having a wavelength of 800 to 1200 nm. 
     
     
         9 . The core-sheath type composite fiber according to  claim 1 , which has an L* value of 16.5 or less.