Inkjet Printing Pre-coat for Surface Relief Control
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Solution Overview
Problem
Inkjet printing on closed surfaces like plastic or certain types of paper faces issues with ink thickness variations leading to relief formation and poor printing accuracy, as ink drops do not penetrate the substrate, and existing solutions do not effectively address ink fixation and absorption problems.
Innovation Solution
An inkjet printing system that includes a station for depositing a solidifiable translucent fluid with variable thickness upstream of the printing station to control ink deposition and prevent relief formation, using UV radiation for polymerization and surface tension management between 15 and 28 mN/m to ensure even ink distribution and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If inkjet printing is performed on closed surfaces with standard ink thickness, then printing can be completed, but thickness variations of about sixty microns occur between printed and non-printed regions, forming relief on the substrate
Solution Approach 1:
A preliminary coating layer is applied to the substrate before inkjet printing. This pre-coat creates a uniform base layer that compensates for the closed surface characteristics, ensuring consistent ink absorption and preventing relief formation. The pre-coat is applied uniformly across the entire substrate surface, including both printed and non-printed regions.
Solution Approach 2:
The system applies different thicknesses of pre-coat material to different regions of the substrate based on the print pattern. Areas that will be printed receive different pre-coat thickness compared to non-printed areas, optimizing ink absorption locally and maintaining surface uniformity.
2Manufacturing precision
If ink drops are deposited on closed substrate surfaces, then printing can proceed, but the ink does not penetrate the substrate and presents an evasive effect by spreading on the substrate surface, leading to printing accuracy problems
Solution Approach 1:
The substrate surface is pre-treated with a coating layer before inkjet printing to modify surface properties. This pre-coat creates optimal surface energy characteristics that control ink spreading and improve penetration, eliminating the evasive effect on closed surfaces.
Solution Approach 2:
The surface tension and porosity parameters of the substrate are modified by applying a pre-coat layer. This changes the substrate's interaction with ink, enabling controlled penetration and preventing unwanted spreading while maintaining printing accuracy.
3Reliability
If paper-type fibrous substrate is used to obtain better fixation, then ink fixation improves, but the ink penetration alters the quality of printing on the substrate
Solution Approach 1:
Instead of using uniformly porous paper substrates, the system applies a pre-coat layer that creates local variations in porosity and absorption characteristics. This allows controlled ink fixation in printed areas while maintaining surface quality, avoiding the drawbacks of uniform fibrous substrate penetration.
4Reliability
If surface tension of the ink is reduced to limit penetration into the substrate, then ink fixation improves, but the ink retains its relief effect on the substrate surface
Solution Approach 1:
A pre-coat layer is applied to the substrate before printing to modify surface tension characteristics. This pre-treatment allows the use of inks with reduced surface tension for better fixation while the pre-coat prevents excessive surface relief by providing a uniform absorption base.
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 system achieves a finished product with a smooth, flat surface by controlling ink thickness and preventing ink spreading, enhancing printing accuracy and quality without additional substrate treatment or finishing steps.
Implementation Method 1
using UV radiation for polymerization
Implementation Method 2
surface tension management between 15 and 28 mN/m to ensure even ink distribution and adhesion
Data Source
AI summary
An ink jet printing system to obtain a finished product comprising a printing station using nozzles with liquid ink for inkjet printing of at least one image on the surface of a suitable substrate. The system also includes at least a first deposit station with nozzles depositing a variable thickness of a solidifying translucent liquid on the substrate surface to produce a finished product without relief, positioned upstream of the drying station of the printed image relative to the direction of movement of the substrate in the system.