Invisible Fluorescent Toner for Security Printing
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Solution Overview
Problem
Current fluorescent toners used in security documents often appear colored under visible light, compromising their effectiveness as hidden security features, and there is a need for improved methods to produce toners suitable for security printing that are invisible under normal conditions but detectable under ultraviolet light.
Innovation Solution
The development of ultra low melt electrophotographic (EA) toner compositions comprising amorphous and crystalline resins with optional colorants and waxes, incorporating fluorescent agents that emit light in the ultraviolet spectrum, allowing images to be invisible under normal light but visible under UV illumination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fluorescent toners are used for security printing, then fluorescent security features can be achieved, but the toners appear colored under visible light which compromises their effectiveness as hidden security features
Solution Approach 1:
The patent applies color changes by using fluorescent dyes that are invisible under visible light but emit specific colors under UV illumination. The toner composition includes fluorescent agents that remain dormant under normal lighting conditions and only become visible when exposed to ultraviolet light, thereby achieving hidden security features that change color state based on illumination type.
Solution Approach 2:
The patent changes the optical parameters of the toner by incorporating fluorescent compounds that alter their emission properties based on excitation wavelength. The toner remains invisible under visible light parameters and transitions to visible fluorescent emission when the illumination parameter changes to UV range, solving the contradiction between visibility and security.
2Ease of manufacture
If ultra low melt toner compositions with fluorescent agents are used, then invisible images under normal light can be achieved, but the fusing process requires precise temperature control
Solution Approach 1:
The patent utilizes phase transitions by incorporating crystalline polyester resins with specific melting points that enable the toner to transition from solid to molten state at controlled temperatures. The ultra low melt composition is designed to fuse at lower temperatures than conventional toners, and the phase transition behavior is harnessed to achieve image transfer and fixation while maintaining the fluorescent properties.
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 toner compositions enable the creation of invisible images under normal light conditions that become visible and emit specific colors under UV light, enhancing security features by providing a clear, energy-efficient, and secure printing solution.
Implementation Method 1
at least one component capable of emitting light upon exposure to ultraviolet light at a wavelength of from about 10 nm to about 400 nm
Data Source
AI summary
The present disclosure provides toners and processes for making said toners. In embodiments, the toners are invisible when viewed under natural light, but possess a fluorescent agent that renders them visible when exposed to UV light of a specific wavelength. In other embodiments the toners have a color under natural light, and a different color when exposed to UV light.