Flexible-Web Inkjet Printing with Sizing for Water-Based Inks
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Solution Overview
Problem
High-speed printing on impermeable substrates like plastic or metal webs using water-based inks faces issues such as ink spreading, misregistration, and substrate shrinkage due to temperature, leading to poor image quality and unusable products.
Innovation Solution
A printing system with individually controllable ink jet imager units and closed-loop control systems to manage web handling, resolution, registration, and drying, using water-based inks with additives to prevent ink spreading and substrate deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If water-based inks are used for printing on impermeable substrates, then environmental and health concerns are addressed, but ink spreading occurs leading to poor image quality
Solution Approach 1:
A sizing composition is applied to the substrate before printing to act as an intermediary layer. This sizing layer modifies the substrate surface properties to control ink behavior, preventing water-based inks from spreading on impermeable surfaces while maintaining environmental benefits of water-based ink chemistry.
Solution Approach 2:
The patent changes the surface energy and porosity parameters of the substrate by applying a sizing composition. This modification alters the interaction between water-based ink and substrate, controlling capillary action and ink spreading to maintain image quality while using environmentally friendly water-based inks.
2Productivity
If high-speed printing is used, then productivity increases, but ink droplets spread and coalesce adversely affecting image quality
Solution Approach 1:
The sizing composition is applied to the substrate before the high-speed printing process. This preliminary treatment prepares the substrate surface to resist ink spreading during rapid printing operations, enabling high productivity without sacrificing image quality due to droplet coalescence.
3Object-affected harmful factors
If water-based inks are deposited on impermeable web, then environmental concerns are addressed, but ink retransfer occurs where ink is unintentionally transferred to rollers
Solution Approach 1:
The sizing composition serves as a intermediary barrier between the water-based ink and the printing rollers. This layer prevents direct contact and unintentional ink transfer to rollers while allowing the water-based ink to remain on the substrate, ensuring process reliability and eliminating the need for solvent-based inks.
4Productivity
If temperature control is not maintained, then substrate shrinkage and deformation occur leading to unusable product
Solution Approach 1:
The patent implements a closed-loop feedback control system that continuously monitors substrate temperature and adjusts heating elements accordingly. This feedback mechanism prevents temperature excursions that would cause shrinkage or deformation, enabling high-speed printing while maintaining substrate dimensional integrity.
Solution Approach 2:
The system dynamically adjusts the thermal parameters of the printing environment to stay within the substrate's safe operating range. By controlling temperature as a critical parameter, the system enables high productivity without causing substrate shrinkage or deformation.
5Adaptability or versatility
If multiple imager units are used for duplex printing, then printing capability is enhanced, but registration accuracy between units becomes difficult to maintain
Solution Approach 1:
The system employs feedback control mechanisms that continuously monitor and adjust the positioning of multiple imager units. This ensures accurate registration between different printing units performing duplex printing, maintaining precision while enhancing printing capability.
Solution Approach 2:
The patent describes a printing system with multiple imager units capable of performing various printing functions on different surfaces of the substrate. The system maintains registration accuracy across all units through coordinated control, enabling versatile duplex printing while preserving manufacturing precision.
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
Achieves high-quality duplex printing on heat-shrinkable webs by controlling ink application, registration, and drying without substrate deformation, ensuring accurate image reproduction and product integrity.
Implementation Method 1
a first imager unit for applying a first printing composition to the web, a second imager unit for applying a second printing composition to the web
Implementation Method 2
Since inks dry primarily via evaporation during a drying and/or curing period
Implementation Method 3
it may be necessary: 1.) to control material shrinkage during imaging so that the resulting imaged film may be subsequently used in a shrink-wrap process, and 2.) to avoid system control problems by minimizing dynamic interactions between system components due to the elastic deformability of the substrate
Implementation Method 4
the lack of ability of the water-based ink to penetrate or absorb into the web itself leads to individual ink droplets spreading across the surface of the web
Data Source
AI summary
A printing system comprises a transport apparatus adapted to transport a flexible web (24) along a process direction and first and second individually controllable inkjet imager units (44, 60, 70, 82) offset from one another along the process direction. Each of the first imager unit and the second imager unit includes a first portion (226) operable to print on a first portion of the web and a second portion (228) operable to print on the second portion of the web wherein each of the first portion and second portion of the first and second imager units is stationary along the process direction and the lateral direction.