Hexaboride Particle Dispersion for Offset Printing
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Solution Overview
Problem
Existing near infrared absorbing materials for offset printing, such as phthalocyanine compounds and tin-doped indium oxide, face issues with temperature sensitivity, durability, and visibility, while hexaboride fine particles dispersed in organic solvents can dissolve rubber blankets, making them unsuitable for offset printing.
Innovation Solution
A near infrared absorbing fine particle dispersion liquid using hexaboride fine particles dispersed in vegetable oils or vegetable oil-derived compounds with a dispersant, maintaining a viscosity of 180 mPa·s or less, and incorporating a binder for stable and clear contrast in offset printing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hexaboride fine particles are dispersed in organic solvents, then near infrared absorbing function is achieved, but rubber blanket dissolves making it unsuitable for offset printing
Solution Approach 1:
A surfactant is introduced as an intermediary substance between the hexaboride fine particles and the water-based solvent. The surfactant has hydrophilic head groups that interact with water and hydrophobic tail groups that interact with the hexaboride particles, enabling stable dispersion without using organic solvents that would dissolve the rubber blanket.
Solution Approach 2:
The invention changes the fundamental parameter of the dispersion medium from organic solvent to water-based solvent. This parameter change eliminates the harmful effect of organic solvent on the rubber blanket while maintaining the near infrared absorbing function through proper particle dispersion using surfactants.
2Reliability
If infrared absorbing material is used to prevent counterfeiting, then security function is improved, but visibility and appearance are obscured
Solution Approach 1:
The hexaboride fine particles exhibit selective optical properties: they strongly absorb near infrared light (wavelengths beyond visible range) while being substantially transparent to visible light (wavelengths 380-780 nm). This local quality differentiation in the optical response allows the material to provide anti-counterfeit functionality without compromising the visual appearance and readability of printed documents.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables effective offset printing with clear contrast and anti-counterfeit properties, preventing duplication and allowing mechanical authentication, while maintaining design flexibility and high anti-counterfeit effectiveness.
Implementation Method 1
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); wherein a lattice constant of the near infrared absorbing fine particles is 0.4100 nm or more and 0.4160 nm or less
Data Source
AI summary
A near infrared absorbing-fine-particle dispersion liquid having absorption in a near infrared region, having clear contrast, and being applicable to offset printing; a method for producing the same; an anti-counterfeit ink composition using the near infrared absorbing-fine-particle dispersion liquid; and anti-counterfeit printed matter using the near infrared absorbing-fine-particles. The near infrared absorbing-fine-particle dispersion liquid contains a solvent of one or more from vegetable oils or vegetable oil-derived compounds; near infrared absorbing-fine-particles of 2 mass % or more and 25 mass % or less, selected from one or more of hexaboride fine-particles expressed by formula XBa (where X is one or more kinds of specified elements, and 4.0≤a≤6.2); and a dispersant soluble in solvent and having a fatty acid in its structure, where the viscosity is 180 mPa·s or less. The anti-counterfeit printed matter is excellent in anti-counterfeit effect due to the near infrared absorbing-fine-particles.