Near infrared absorbing fine particle dispersion liquid and method for producing the same, anti-counterfeit ink composition using near infrared absorbing fine particle dispersion liquid, and anti-counterfeit printed matter using near infrared absorbing fine particles

Abstract

Provided are a near infrared absorbing fine particle dispersion liquid having an absorption ability in a near infrared region, a clear contrast, and applicable to offset printing, and a method for producing the same, an anti-counterfeit ink composition using the near infrared absorbing fine particle dispersion liquid and an anti-counterfeit printed matter using near infrared absorbing fine particles. Also provided are a near infrared absorbing fine particle dispersion liquid containing a solvent of one or more kinds selected from petroleum-based solvents; near infrared absorbing fine particles in an amount of 2 mass % or more and 25 mass % or less, selected from one or more kinds of hexaboride fine particles expressed by a general formula XBa, and a dispersant soluble in the solvent and having a fatty acid in its structure, and an anti-counterfeit ink composition containing the near infrared absorbing fine particle dispersion liquid.

1 . A near infrared absorbing fine particle dispersion liquid, containing:
 a solvent of one or more kinds selected from petroleum-based solvents;   near infrared absorbing fine particles in an amount of 2 mass % or more and 25 mass % or less, selected from one or more kinds of hexaboride fine particles expressed by a general formula XBa (wherein element X is at least one or more kinds selected from a group consisting of La, Ce, Pr, Nd, Gd, Tb, Dy, Ho, Y, Sm, Eu, Er, Tm, Yb, Lu, Sr, and Ca, satisfying 4.0≦a≦6.2); and   a dispersant soluble in the solvent and having a fatty acid in its structure,   wherein viscosity is 180 mPa/S or less.   
     
     
         2 . The near infrared absorbing fine particle dispersion liquid according to  claim 1 , wherein the dispersant has one kind or more selected from a secondary amine group, a tertiary amine group, and a quaternary ammonium group as a functional group. 
     
     
         3 . The near infrared absorbing fine particle dispersion liquid according to  claim 1 , wherein the dispersant has an acid value of 1 mg KOH/g or more. 
     
     
         4 . The near infrared absorbing fine particle dispersion liquid according to  claim 1 , wherein a dispersed particle size of each near infrared absorbing fine particle is 1 nm or more and 200 nm or less. 
     
     
         5 . The near infrared absorbing fine particle dispersion liquid according to  claim 1 , wherein a surface of each near infrared absorbing fine particle is coated with a compound of one or more kinds selected from Si, Ti, Al, and Zr. 
     
     
         6 . The near infrared absorbing fine particle dispersion liquid according to  claim 1 , wherein a lattice constant of the near infrared absorbing fine particle is 0.4100 nm or more and 0.4160 nm or less. 
     
     
         7 . The near infrared absorbing fine particle dispersion liquid according to  claim 1 , wherein the solvent is one or more kinds selected from petroleum-based solvents having an aniline point of from 75° C. or more and 95° C. or less and a boiling point of from 150° C. or more and 340° C. or less. 
     
     
         8 . The near infrared absorbing fine particle dispersion liquid according to  claim 1 , wherein the near infrared absorbing fine particle dispersion liquid further contains a binder. 
     
     
         9 . A method for producing the near infrared absorbing fine particle dispersion liquid according to  claim 1 , comprising:
 mixing and dispersing the near infrared absorbing fine particles, the solvent, and the dispersant.   
     
     
         10 . An anti-counterfeit ink composition, containing the near infrared absorbing fine particle dispersion liquid of  claim 1 . 
     
     
         11 . The anti-counterfeit ink composition according to  claim 10  further containing a pigment. 
     
     
         12 . The anti-counterfeit ink composition, wherein the pigment of  claim 11  is an inorganic pigment and is one or more kinds selected from carbon black, white pigment, an extender pigment, a red pigment, a yellow pigment, a green pigment, a blue pigment, a purple pigment, a fluorescent pigment, a temperature indicating pigment, a pearl pigment, and a metal powder pigment. 
     
     
         13 . The anti-counterfeit ink composition, wherein the pigment of  claim 11  is an organic pigment and is one or more kinds selected from an azo lake pigment, an insoluble azo pigment, a condensed azo pigment, a phthalocyanine pigment, and a condensed polycyclic pigment. 
     
     
         14 . The anti-counterfeit ink composition according to  claim 10 , containing one or more kinds selected from a plasticizer, an antioxidant, a thickener, and a wax. 
     
     
         15 . An anti-counterfeit printed matter having a printed pattern on one side or both sides of a base material, containing near infrared absorbing fine particles of one or more kinds of hexaboride fine particles expressed by a general formula XBa (wherein element X is at least one or more kinds selected from a group consisting of La, Ce, Pr, Nd, Gd, Tb, Dy, Ho, Y, Sm, Eu, Er, Tm, Yb, Lu, Sr, and Ca, satisfying 4.0≦a≦6.2), in the printed pattern. 
     
     
         16 . An anti-counterfeit printed matter, wherein the printed pattern of  claim 15  further contains a pigment. 
     
     
         17 . An anti-counterfeit printed matter, wherein the pigment of  claim 16  is an inorganic pigment, and is one or more kinds selected from carbon black, white pigment, an extender pigment, a red pigment, a yellow pigment, a green pigment, a blue pigment, a purple pigment, a fluorescent pigment, a temperature indicating pigment, a pearl pigment, and a metal powder pigment. 
     
     
         18 . An anti-counterfeit printed matter, wherein the pigment of  claim 16  is an organic pigment and is one or more kinds selected from an azo lake pigment, an insoluble azo pigment, a condensed azo pigment, a phthalocyanine pigment, and a condensed polycyclic pigment. 
     
     
         19 . The anti-counterfeit printed matter according to  claim 15 , wherein a value obtained by dividing an average value of a diffuse reflectance of the anti-counterfeit printed matter in a wavelength range of 800 nm to 1300 nm, by an average value of a diffuse reflectance of a blank not containing near infrared absorbing fine particles in a wavelength range of 800 nm to 1300 nm, is 0.84 or less.