Pressure-sensitive adhesive containing near infrared absorbing coloring matter

Abstract

A pressure-sensitive adhesive containing a near infrared absorbing dye having excellent shielding function for near infrared rays and excellent in durability is provided. In a light resistance test, a layer of the pressure-sensitive adhesive having a thickness of 25±5 μm has an absorption intensity at the maximum absorption wavelength of the near infrared absorbing dye after a light resistance test of 50% or more of the absorption intensity before the test in which light with an irradiance of 64.5 W/m 2 at a wavelength of 300 to 400 nm is irradiated on the layer for 160 hours.

1 . A pressure-sensitive adhesive comprising at least one near infrared absorbing dye represented by formula (4) or (5): 
       
         
           
           
               
               
           
         
         wherein 
         in formula (4), R a  indicates a linear chain or branched chain alkyl group having 3 to 6 carbon atoms and R b  indicates a linear chain or branched chain alkoxy group having 1 to 6 carbon atoms or a linear chain or branched chain alkyl group having 1 to 5 carbon atoms, with the proviso that R b  is a same group as OR a  in case of a branched alkoxy group, 
         R c  indicates a hydrogen atom, or a linear chain or branched chain alkyl group having 1 to 5 carbon atoms, or a benzene ring which may optionally have a substituent comprising an alkyl group, an alkoxy group, a substituted amino group or a halogen atom, or a phenylthio group which may optionally have a substituent comprising an alkyl group, an alkoxy group, a substituted amino group or a halogen atom; 
       
       
         
           
           
               
               
           
         
         wherein 
         in formula (5), R 5  and R 6  indicate a hydrocarbon group which may optionally have a substituent, a carbonyl group which may optionally have a substituent, a cyano group, a halogen atom or a hydrogen atom, R 7  and R 8  indicate an alkyl group which may optionally have a substituent, or an aryl group which may optionally have a substituent, and 
         M 4  is a metal atom receiving a planar quadridentate ligand. 
       
     
     
         2 . The pressure-sensitive adhesive according to  claim 1 , wherein in formula (4), R b  indicates a branched chain alkoxy group and is a same group as OR a . 
     
     
         3 . The pressure-sensitive adhesive according to  claim 1 , wherein in formula (5), R 5  is a phenyl group in which a substituent is situated at least at an ortho-position. 
     
     
         4 . The pressure-sensitive adhesive comprising a near infrared absorbing dye according to  claim 1  further comprising an acryl polymer. 
     
     
         5 . A near infrared absorption filter comprising a layer of the pressure-sensitive adhesive according to any one of  claims 1  to  4 . 
     
     
         6 . A front filter for plasma display comprising the near infrared absorption filter having a layer of the pressure-sensitive adhesive according to any one of  claims 1  to  4 . 
     
     
         7 . A near infrared absorbing dye of formula (4) or (5): 
       
         
           
           
               
               
           
         
         wherein 
         R a  indicates a linear chain or branched chain alkyl group having 3 to 6 carbon atoms and R b  indicates a linear chain or branched chain alkoxy group having 1 to 6 carbon atoms or a linear chain or branched chain alkyl group having 1 to 5 carbon atoms, with the proviso that R b  is a same group as OR a  in case of a branched alkoxy group, 
         R c  indicates a hydrogen atom, or a linear chain or branched chain alkyl group having 1 to 5 carbon atoms, or a benzene ring which may optionally have a substituent comprising an alkyl group, an alkoxy group, a substituted amino group or a halogen atom, or a phenylthio group which may optionally have a substituent comprising an alkyl group, an alkoxy group, a substituted amino group or a halogen atom; 
       
       
         
           
           
               
               
           
         
         wherein 
         R 5  and R 6  indicate a hydrocarbon group which may optionally have a substituent, a carbonyl group which may optionally have a substituent, a cyano group, a halogen atom or a hydrogen atom, 
         R 7  and R 8  indicate an alkyl group which may optionally have a substituent, or an aryl group which may optionally have a substituent, and 
         M 4  is a metal atom receiving a planar quadridentate ligand. 
       
     
     
         8 . The near infrared absorbing dye according to  claim 7 , wherein
 R b  indicates a branched chain alkoxy group and is a same group as OR a .   
     
     
         9 . The near infrared absorbing dye according to  claim 7 , wherein R 5  is a phenyl group in which a substituent is situated at least at an ortho-position.