Polarizing fiber, polarizer, polarizing plate, laminated optical film, and image display

Abstract

As the polarizing fiber of the present invention, the cross sectional form perpendicular to the longitudinal direction has a sea-island structure, and the cross sectional form is continuously made up in the longitudinal direction. A resin (sea component) that constitutes the sea region of the sea-island structure comprises a dichroic dye, and a resin (island component) that constitutes the island regions of the sea-island structure is a transparent resin. The polarizing fiber of the present invention may be used as a forming material of a polarizer, for example. By using the above polarizing fiber, a polarizer wherein unevenness of the transmittance is small and cracks are less generated may be formed.

1 . A polarizing fiber having an absorption axis in the longitudinal direction thereof, wherein the cross sectional form perpendicular to the longitudinal direction has a sea-island structure, and the cross sectional form is continuously made up in the longitudinal direction, and
 wherein a resin (sea component) that constitutes the sea region of the sea-island structure comprises a dichroic dye, and   a resin (island component) that constitutes the island regions of the sea-island structure is a transparent resin.   
     
     
         2 . The polarizing fiber according to  claim 1 , wherein when the refractive index of the island component in the direction perpendicular to the longitudinal direction is represented by n i1  and the refractive index of the sea component in the direction perpendicular to the longitudinal direction is represented by n s1 , the difference between the refractive indexes, Δn 1 =|n s1 −n i1 |, is 0.02 or less, and
 when the refractive index of the island component in the longitudinal direction is represented by n i2  and the refractive index of the sea component in the longitudinal direction is represented by n s2 , the difference between the refractive indexes, Δn 2 =|n s2 −n i2 |, is 0.03 or more and 0.05 or less.   
     
     
         3 . The polarizing fiber according to  claim 1 , wherein the number of the island regions is 2 or more, and further the long diameter of each of the island regions is from 0.1 to 8.0 μm. 
     
     
         4 . The polarizing fiber according to  claim 1 , wherein the resin that constitutes the sea region is polyvinyl alcohol or ethylene vinyl alcohol copolymer. 
     
     
         5 . A polarizer in a sheet form, wherein the polarizing fiber as recited in  claim 1  is arranged or laminated in parallel to the longitudinal direction thereof, and is further enveloped in a transparent isotropic material. 
     
     
         6 . The polarizer according to  claim 5 , wherein when the refractive index of the isotropic material is represented by n m  and the refractive index of the sea component in the direction perpendicular to the longitudinal direction is represented by n s1 , the difference between the refractive indexes, Δn 3 =|n s1 −n m |, is 0.02 or less. 
     
     
         7 . A polarizing plate, having a transparent protective film on at least one surface of the polarizer as recited in  claim 5 . 
     
     
         8 . A laminated optical film, having the polarizer as recited in  claim 5 . 
     
     
         9 . An image display, having the polarizer as recited in  claim 5 . 
     
     
         10 . A laminated optical film, having the polarizing plate as recited in  claim 7 . 
     
     
         11 . An image display, having the polarizing plate as recited in  claim 7 . 
     
     
         12 . An image display, having the laminated optical film as recited in  claim 8 . 
     
     
         13 . An image display, having the polarizer as recited in  claim 6 . 
     
     
         14 . A laminated optical film, having the polarizer as recited in  claim 6 .