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 vegetable oils or vegetable oil-derived compounds; 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 XB a (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, and an anti-counterfeit ink composition containing the near infrared absorbing fine particle dispersion liquid. Also provided is an anti-counterfeit printed matter excellent in anti-counterfeit effect due to the printed matter containing the near infrared absorbing fine particles.

1 . A near infrared absorbing fine particle dispersion liquid, containing:
 a solvent of one or more kinds selected from vegetable oils or vegetable oil-derived compounds;   near infrared absorbing fine particles in an amount of 2 mass % or more and 25 mass % or less, containing one or more kinds of hexaboride fine particles expressed by a general formula XB a  (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 an anchor portion of the dispersant has one or more kinds selected from a secondary amino group, a tertiary amino group, and a quaternary ammonium group. 
     
     
         3 . The near infrared absorbing fine particle dispersion liquid according to  claim 1  or  2 , 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 any one of  claims 1  to  3 , 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 any one of  claims 1  to  4 , wherein a lattice constant of the near infrared absorbing fine particle is 0.4100 nm or more and 0.4160 nm or less. 
     
     
         6 . The near infrared absorbing fine particle dispersion liquid according to any one of  claims 1  to  5 , wherein a surface of the near infrared absorbing fine particle is coated with a compound of one or more kinds selected from Si, Ti, Al, and Zr. 
     
     
         7 . The near infrared absorbing fine particle dispersion liquid according to any one of  claims 1  to  6 , wherein the vegetable oil is one or more kinds of vegetable oils selected from drying oil and semidrying oil. 
     
     
         8 . The near infrared absorbing fine particle dispersion liquid according to any one of  claims 1  to  7 , 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 any one of  claims 1  to  8 , 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 any one of  claims 1  to  8 . 
     
     
         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 any one of  claims 10  to  13 , 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 XB a  (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 any one of  claims 15  to  18 , 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.