Polarizing plate and circularly polarizing plate

Abstract

A polarizing plate including a substrate and a polarizer is provided. The polarizer has a polarizing layer having a thickness of 5 μm or less in which a dichroic dye is oriented. The absorbance in the absorption axis direction (A1) of the polarizer at a wavelength of 380 to 760 nm is 0.3 or more and 1.5 or less, and the absorbance in the transmission axis direction (A2) is 0.001 or more and 0.15 or less.

1 .- 8 . (canceled) 
     
     
         9 . A polarizing plate comprising a substrate and a polarizer,
 wherein the polarizer has a polarizing layer having a thickness of 5 μm or less in which a dichroic dye is oriented,   an absorbance in the absorption axis direction (A1) of the polarizer at a wavelength of 380 to 760 nm is 0.3 or more and 1 or less, and an absorbance in a transmission axis direction (A2) is 0.001 or more and 0.10 or less, and
 wherein the dichroic dye includes: 
   (i) a dye represented by formula (1):   
       
         
           
           
               
               
           
         
         
           wherein Y is a group represented by one of formulas (Y1) and (Y2): 
         
       
       
         
           
           
               
               
           
         
         
           L is an oxygen atom or —NR—, 
           R is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, 
           R 1  is a group represented by one of formulas (R 1 -1), (R 1 -2) and (R 1 -3): 
         
       
       
         
           
           
               
               
           
         
         
           wherein each ma represents an integer of 0 to 10, 
           R 2  is a group represented by one of formulas (R 2 -1), (R 2 -2), (R 2 -3), (R 2 -4), (R 2 -5) and (R 2 -6): 
         
       
       
         
           
           
               
               
           
         
         
           
             and wherein each mb is an integer of 0 to 10; and 
           
         
         (ii) a dye represented by formula (2): 
       
       
         
           
           
               
               
           
         
         
           wherein n is 1 or 2, 
           Ar 1  and Ar 3  each represents a group represented by one of formulas (AR-1), (AR-2), (AR-3) and (AR-4): 
         
       
       
         
           
           
               
               
           
         
         
           Ar 2  is a group represented by one of formulas (AR2-1), (AR2-2) and (AR2-3): 
         
       
       
         
           
           
               
               
           
         
         
           A 1  and A 2  each represents a group represented by one of formulas (A-1) to (A-9): 
         
       
       
         
           
           
               
               
           
         
         and wherein me is an integer of 0 to 10. 
       
     
     
         10 . The polarizing plate according to  claim 9 , wherein the azobenzene site of the dye represented by formula (1) has trans geometric isomerism. 
     
     
         11 . The polarizing plate according to  claim 9 , wherein in the formula (1), Y is a group represented by the formula (Y1). 
     
     
         12 . The polarizing plate according to  claim 9 , wherein the polarizing layer comprises a polymer of a polymerizable liquid crystal compound exhibiting a smectic liquid crystal phase. 
     
     
         13 . The polarizing plate according to  claim 9 , wherein the alkyl group is selected from the group consisting of a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group and a t-butyl group. 
     
     
         14 . The polarizing plate according to  claim 9 , wherein R 1  is a group represented by one of the formulas (R 1 -2) and (R 1 -3). 
     
     
         15 . The polarizing plate according to  claim 9 , wherein in formula (R 1 -2), each ma represents an integer of 0 to 5. 
     
     
         16 . The polarizing plate according to  claim 9 , wherein R 2  is a group represented by one of the formulas (R 2 -2), (R 2 -5) and (R 2 -6). 
     
     
         17 . The polarizing plate according to  claim 9 , wherein in formulas (R 2 -1), (R 2 -2), (R 2 -3), (R 2 -5) and (R 2 -6), each mb is an integer of 0 to 5. 
     
     
         18 . The polarizing plate according to  claim 9 , wherein the azobenzene site of the dye represented by formula (2) has trans geometric isomerism. 
     
     
         19 . The polarizing plate according to  claim 9 , wherein the dichroic dye is an organic dye. 
     
     
         20 . The polarizing plate according to  claim 9 , wherein the polymerizable liquid crystal compound is a compound exhibiting a higher smectic liquid crystal phase. 
     
     
         21 . The polarizing plate according to  claim 9 , wherein L is an oxygen atom. 
     
     
         22 . The polarizing plate according to  claim 9 , wherein the dye represented by formula (1) is a compound represented by one of formulas (1-1) to (1-8): 
       
         
           
           
               
               
           
         
       
     
     
         23 . The polarizing plate according to  claim 9 , wherein the dye represented by formula (2) is a compound represented by one of formulas (2-11) to (2-36): 
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
       
     
     
         24 . The polarizing plate according to  claim 9 , wherein the polarizer exhibits a Bragg peak in X-ray diffraction measurement. 
     
     
         25 . A circularly polarizing plate comprising the polarizing plate according to  claim 9  and a ¼ wavelength plate. 
     
     
         26 . The circularly polarizing plate according to  claim 25 , wherein a birefringence of the ¼ wavelength plate to light having a wavelength of 450 nm, a birefringence to light having a wavelength of 550 nm, and a birefringence to light having a wavelength of 650 nm have reverse wavelength dispersibility satisfying relationships represented by the following expressions (II) and (III):
   Δ n (450)/Δ n (550)≤1.00  (II)
 
   1.00≤Δ n (650)/Δ n (550)  (III)
 
 wherein Δn(λ) represents a birefringence to light having a wavelength λ nm.