Thermoplastic Substrate Preformed Recesses for Ink Jet Image Durability
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Solution Overview
Problem
Existing methods for printing images on thermoplastic substrates used in security instruments, such as identification cards, face issues with adhesion, durability, and security against tampering, with ink jet printing and UV cured inks not providing adequate protection and being prone to separation and wear.
Innovation Solution
The use of preformed recessed image receiving surfaces on thermoplastic substrates with specific dimensions and patterns, such as cell and bridge patterns, to enhance adhesion and durability, and optionally incorporating latent and hidden images for added security, which are printed using ink jet printing with UV curable ink.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ink jet printing with UV cured ink is used to print images on thermoplastic substrates, then the images can be applied to the surface, but the adhesion is insufficient and images are prone to separation
Solution Approach 1:
The patent applies preliminary action by pre-forming recesses in the thermoplastic substrate before printing the image. These recesses are created in advance to receive and mechanically anchor the printed image material, ensuring better adhesion from the outset rather than relying solely on surface chemistry or post-printing protective layers.
Solution Approach 2:
The invention implements local quality by creating localized recesses at specific positions where images will be printed. This concentrates the adhesion enhancement mechanism precisely where needed, allowing the image to be embedded in recessed areas with increased surface area and mechanical interlocking, while the rest of the substrate maintains its original properties.
2Reliability
If a clear coating or protective patch is applied over the printed image, then additional protection is provided, but manufacturing cost increases and the patch may separate from the image
Solution Approach 1:
The protective function is built into the substrate structure in advance through pre-formed recesses. The image material is deposited into these recesses during the printing process itself, creating mechanical interlocking and embedment protection without requiring subsequent application of separate protective coatings or patches.
Solution Approach 2:
The invention merges the protective function with the substrate structure itself. Instead of adding a separate protective layer on top of the printed image, the recesses in the substrate provide both image reception and protection in a single integrated structure, eliminating the need for additional protective patches or coatings.
3Ease of manufacture
If the thermoplastic substrate surface is kept smooth or matte, then printing can be performed, but the images lack durability and wear resistance
Solution Approach 1:
The substrate is pre-formed with recesses before the printing process. This preliminary structural modification allows the printed image material to be deposited into these recesses, where it gains mechanical protection and wear resistance through embedment, while the printing process itself remains compatible with standard ink jet methods.
Solution Approach 2:
The invention transitions from a two-dimensional surface printing approach to a three-dimensional solution by creating recesses that give the substrate surface relief. The image is no longer just on the surface but is embedded within the substrate topography, adding a depth dimension that provides mechanical protection and wear resistance.
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 provides improved adhesion, durability, and security features, with the preformed recessed surfaces enhancing the resistance to wear and tampering, and the latent and hidden images providing additional verification mechanisms.
Implementation Method 1
the UV cured ink jet image is applied to the surface of the thermoplastic substrate
Implementation Method 2
A protective patch typically comprises a UV cured varnish which is also applied by means of ink jet printing
Data Source
AI summary
A method is provided by the invention for printing surface applied images to a thermoplastic substrate to provide improved durability to the printed image. A thermoplastic substrate comprises in a predetermined area a pattern, preferably a cell pattern, of recessed image receiving surfaces below a nominal surface of the thermoplastic substrate and a pattern of bridges separating the recessed image receiving surfaces, the depths of the recessed image receiving surfaces and the areas of the bridges separating the recessed image receiving surfaces, relative to the areas of the recessed image receiving surfaces, chosen to provide durability to the image after the image has been printed onto the predetermined area. The image may be printed by ink jet printing. To additionally provide security features to the security instrument, latent and hidden images may be formed by latent image recesses and hidden image recesses, respectively, below the nominal surface.