Light-shielding paint, light-shielding paint set, light-shielding film, optical element, and method for producing optical element

Abstract

An optical element has a lanthanum-containing glass substrate and a light-shielding film on part of the surface of the glass substrate. The light-shielding film is made from a light-shielding paint that contains at least an epoxy resin, fine particles of titania, a dye, an organic solvent, and an amine-based curing agent. The organic solvent in the light-shielding paint has a vapor pressure of 160 Pa or more and 960 Pa or less at a temperature of 20° C. The viscosity of the light-shielding paint is 10.0 mPa·s or more and 100 mPa·s or less.

What is claimed is: 
     
         1 . An optical element comprising:
 a glass substrate; and   a light-shielding film on part of a surface of the glass substrate,   wherein:   the glass substrate contains lanthanum;   the light-shielding film is made from a light-shielding paint containing at least an epoxy resin, fine particles of titania, a dye, an organic solvent, and an amine-based curing agent; and   the organic solvent in the light-shielding paint has a vapor pressure of 160 Pa or more and 960 Pa or less at a temperature of 20° C.   
     
     
         2 . The optical element according to  claim 1 , wherein
 a viscosity of the light-shielding paint is 10.0 mPa·s or more and 100 mPa·s or less.   
     
     
         3 . The optical element according to  claim 1 , wherein:
 the organic solvent includes a first organic solvent and a second organic solvent; and   the first organic solvent has a boiling point of 150° C. or more and 210° C. or less.   
     
     
         4 . The optical element according to  claim 3 , wherein
 the first organic solvent is benzyl alcohol, 2-ethyl-1-hexanol, butyl cellosolve, 1-butoxy-2-propanol, or a mixture thereof.   
     
     
         5 . The optical element according to  claim 3 , wherein
 the second organic solvent is propylene glycol monomethyl ether.   
     
     
         6 . The optical element according to  claim 1 , wherein
 the substrate is a lens or a prism.   
     
     
         7 . The optical element according to  claim 1 , wherein
 the substrate has a refractive index of 1.60 or more and 2.00 or less.   
     
     
         8 . A light-shielding paint comprising:
 an epoxy resin;   fine particles of titania;   a dye;   an organic solvent; and   an amine-based curing agent, wherein   the organic solvent has a vapor pressure of 160 Pa or more and 960 Pa or less at a temperature of 20° C.   
     
     
         9 . The light-shielding paint according to  claim 8 , wherein
 a viscosity of the light-shielding paint is 10.0 mPa·s or more and 100 mPa·s or less.   
     
     
         10 . The light-shielding paint according to  claim 8 , wherein:
 the organic solvent includes a first organic solvent and a second organic solvent; and   the first organic solvent has a boiling point of 150° C. or more and 210° C. or less.   
     
     
         11 . The light-shielding paint according to  claim 10 , wherein
 the first organic solvent is benzyl alcohol, 2-ethyl-1-hexanol, butyl cellosolve, 1-butoxy-2-propanol, or a mixture thereof.   
     
     
         12 . The light-shielding paint according to  claim 10 , wherein
 the second organic solvent is propylene glycol monomethyl ether.   
     
     
         13 . The light-shielding paint according to  claim 8 , wherein
 the epoxy resin is a bisphenol A epoxy resin.   
     
     
         14 . The light-shielding paint according to  claim 8 , wherein
 an average particle diameter of primary particles of the fine particles of titania is 100 nm or less.   
     
     
         15 . A light-shielding paint set for an optical element, the light-shielding paint comprising:
 two or more units including:   a unit having an epoxy resin; and   a unit having an amine-based curing agent, wherein:   the light-shielding paint set contains fine particles of titania, a dye, and an organic solvent in any one or more of the units; and   the organic solvent in a light-shielding paint as a mixture of all units in the light-shielding paint set has a vapor pressure of 160 Pa or more and 960 Pa or less at a temperature of 20 C.   
     
     
         16 . The light-shielding paint set according to  claim 15 , wherein
 a viscosity of the light-shielding paint as a mixture of all units in the light-shielding paint set is 10.0 mPa·s or more and 100 mPa·s or less.   
     
     
         17 . The light-shielding paint set according to  claim 15 , wherein:
 the organic solvent includes a first organic solvent and a second organic solvent; and   the second organic solvent is propylene glycol monomethyl ether.   
     
     
         18 . A method for producing an optical element having a lanthanum-containing glass substrate and a light-shielding film on part of a surface of the glass substrate, the method comprising:
 applying a light-shielding paint to part of the surface of the glass substrate; and   curing the applied light-shielding paint, wherein:   the light-shielding paint contains at least an epoxy resin, fine particles of titania, a dye, an organic solvent, and an amine-based curing agent; and   the light-shielding paint has a vapor pressure of 160 Pa or more and 960 Pa or less at a temperature of 20° C.   
     
     
         19 . The method according to  claim 18  for producing an optical element, wherein
 a viscosity of the light-shielding paint is 10.0 mPa·s or more and 100 mPa·s or less. 
 
     
     
         20 . The method according to  claim 18  for producing an optical element, wherein:
 the organic solvent includes a first organic solvent and a second organic solvent; and 
 the second organic solvent is propylene glycol monomethyl ether.