Cast-Cure Surface Relief Security Features for Flat Substrates
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Solution Overview
Problem
Existing security features on documents such as banknotes and passports, particularly those using intaglio printing, face limitations in substrate compatibility, deformation, ink transfer, and difficulty in combining with optically variable foils due to high pressure and temperature requirements, leading to reduced security and durability.
Innovation Solution
A surface relief structure formed by cast-cure on a flat substrate, comprising primary and secondary relief elements, allows for low-temperature, low-pressure processing, precise replication of tactile and optical effects, and compatibility with sensitive materials like holographic foils, enhancing security and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If intaglio printing is used to create tactile security features, then high-resolution visual reproduction and tactile protrusions are achieved, but substrate deformation and thermal/pressure damage occur
Solution Approach 1:
The patent replaces the mechanical intaglio printing process with a cast-cure process that uses liquid precursor materials poured into molds. This substitution eliminates the high pressure and thermal deformation associated with traditional intaglio printing while achieving similar tactile relief features through chemical curing of the liquid material in the mold cavity.
Solution Approach 2:
The patent changes the physical state of the security feature material from solid ink (intaglio) to liquid precursor material (cast-cure). This parameter change allows the material to be deposited at low pressure and temperature, then transformed into the final solid relief structure through chemical curing, thereby avoiding substrate damage while maintaining manufacturing precision.
2Strength
If high pressure and temperature are applied during intaglio printing, then tactile relief is achieved, but compatibility with optically variable foils is reduced
Solution Approach 1:
The patent replaces the high-pressure mechanical intaglio printing process with a low-pressure cast-cure process. Liquid precursor materials are poured into molds at atmospheric or low pressure, then cured chemically to form the tactile relief features. This substitution preserves optically variable foils that would be damaged by high-pressure intaglio printing.
Solution Approach 2:
The patent performs preliminary deposition of optically variable foils onto the substrate before applying the liquid precursor material for cast-curing. This preliminary action ensures that the sensitive foils are already in place and protected during the low-pressure casting process, maintaining their integrity and optical properties in the final security device.
3Manufacturing precision
If more ink is transferred to increase tactile quality, then intaglio profile is improved, but substrate deformation increases
Solution Approach 1:
The patent changes the material state from solid ink transfer to liquid precursor pouring. The liquid material flows into the mold cavity under gravity or low pressure, forming the complete relief structure without requiring high ink transfer amounts. This eliminates the substrate deformation that occurs when excessive ink and pressure are applied during traditional intaglio printing.
Solution Approach 2:
The patent replaces the mechanical ink transfer and embossing process with a chemical cast-cure process. Liquid precursors are deposited and then cured in place within the mold, forming the tactile relief features without mechanical pressure on the substrate. This substitution maintains substrate flatness while achieving high manufacturing precision in the relief structure.
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 cast-cure process provides improved substrate compatibility, reduces deformation, enables precise tactile and optical replication, and increases security by allowing greater design flexibility and durability, making counterfeiting more difficult.
Implementation Method 1
The one or more curable materials may be UV-curable or otherwise curable by exposure to a suitable environment or stimulus
Data Source
AI summary
A security device is provided, including: a surface relief structure formed of one or more cured materials on a substantially flat substrate, the surface relief structure defining a primary set of relief elements at a first scale and a secondary set of relief elements at a second scale which is smaller than the first, the primary set of relief elements including a plurality of raised protrusions spaced by recesses and the secondary set of relief elements being disposed on the tops of at least one of the raised protrusions and/or in at least one of the recesses. A security device including a structure formed of cured material(s) and an embossed structure is also provided. Methods of manufacture are also disclosed.