Laser Marking Pigmented Substrates UV Security
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for laser marking on substrates do not effectively create markings that are invisible under ambient light but visible under UV light, limiting their application in security and branding.
Innovation Solution
A polymer composition containing non-fluorescent organic pigments like quinacridone, diketopyrrolopyrrole, and perylene, which change to a fluorescent form when exposed to heat, creating defined domains with higher pigment concentration visible only under UV light without altering the substrate's color under ambient light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional laser marking methods are used to create visible markings on substrates, then the markings are clearly visible under ambient light, but the markings cannot provide security authentication functionality
Solution Approach 1:
The patent changes the optical parameters of the pigment by controlling the thermal history of the substrate. By exposing the substrate to specific temperature ranges (e.g., 50-200°C for 1-24 hours), the pigment transitions from a non-fluorescent form to a fluorescent form, enabling security authentication functionality without adding complex marking devices
Solution Approach 2:
The pigment undergoes a phase transition between different crystalline or molecular forms based on temperature exposure. The non-fluorescent pigment form converts to a fluorescent form through controlled heating, creating a binary state system that provides authentication capability while maintaining simplicity in the marking system design
2Illumination intensity
If pigment concentration is increased to enhance fluorescence visibility under UV light, then the fluorescent marking becomes more apparent, but the substrate color changes under ambient light
Solution Approach 1:
The patent creates local quality differences in the substrate by applying differential thermal treatment. Specific regions are heated to convert pigment to fluorescent form while other regions remain in non-fluorescent form, allowing the substrate to maintain its original appearance under ambient light while providing localized fluorescence under UV illumination for security marking
Solution Approach 2:
The patent uses partial action by exposing only specific domains of the substrate to heat treatment. This selective heating converts pigment to fluorescent form in marked regions while leaving unmarked regions in their original non-fluorescent state, thereby maintaining overall substrate color appearance under ambient light while creating visible fluorescence under UV light in specific areas
3Reliability
If heat treatment is applied to convert pigment to fluorescent form, then security marking capability is achieved, but the processing time and temperature control complexity increase
Solution Approach 1:
The patent incorporates fluorescent pigment precursors into the substrate during the manufacturing process, before the substrate is put into service. This preliminary action ensures that the pigment is already in position and requires only simple thermal activation later, reducing both processing time and complexity when the security marking is actually applied
Solution Approach 2:
The substrate material itself provides the mechanism for security marking through its embedded pigment response to heat. The substrate essentially marks itself when exposed to appropriate thermal conditions, eliminating the need for complex external marking equipment and reducing processing complexity while maintaining authentication reliability
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 method produces markings that are indiscernible under ambient lighting but clearly visible under UV light, providing a secure and unique identification method suitable for security and branding applications.
Implementation Method 1
exposing a composition comprising a polymer and an organic pigment, e.g., quinacridone, diketopyrrolopyrrole (DPP) or perylene pigment etc, to a heat source, such as laser radiation
Implementation Method 2
Some pigments thermally decompose upon heating and change color due to chemical reactions that change the molecular structure
Implementation Method 3
other pigments undergo a change of crystalline structure which changes their color
Implementation Method 4
to produce a fluorescent marking readily apparent under UV light
Data Source
AI summary
A method for producing fluorescent markings on a substrate which method comprises exposing parts of a composition comprising a polymer and an organic pigment to a heat source, such as laser radiation, to produce a fluorescent 5 markings which are are not discernable when viewed under ambient visible light but readily apparent under UV light is disclosed. The method produces novel compositions wherein a fluorescent form of a pigment is present at a higher concentration in defined domains relative to the remainder of the composition. The novel polymer composition is particularly useful in security marking applications.