Transfer Printing Hydrophobic Release Layer Treatment
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Solution Overview
Problem
Indirect printing systems face challenges with inkjet printing on fibrous substrates due to ink wicking, limited resolution, and instability of ink droplets on hydrophobic transfer members, leading to poor image quality and difficulties in duplex printing.
Innovation Solution
A method involving a hydrophobic release layer on an intermediate transfer member treated with a positively charged polymeric chemical agent, which reduces the tendency of ink droplets to bead and spread, allowing for improved ink film formation and transfer to a substrate without significant wetting of the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hydrophobic release layer is used on the intermediate transfer member, then the ink image can be transferred effectively to the substrate, but the ink droplets bead and spread on the surface, causing instability during rapid movement
Solution Approach 1:
The patent changes the surface energy parameters of the hydrophobic release layer by applying a charged chemical agent treatment. This modifies the interfacial tension and surface properties to reduce droplet beading while maintaining transfer effectiveness. The treatment adjusts the chemical composition and charge density of the surface to achieve optimal droplet stability during rapid blanket movement.
2Object-affected harmful factors
If aqueous inks are used, then the carrier liquid is non-toxic and evaporation is easier, but the ink droplets bead excessively on hydrophobic surfaces, making liquid removal difficult
Solution Approach 1:
The charged chemical agent acts as an intermediary between the aqueous ink and the hydrophobic release layer. It modifies the interface properties to reduce surface tension and prevent excessive beading, thereby facilitating easier liquid removal through evaporation or air knife without requiring toxic non-aqueous carriers.
3Ease of manufacture
If inkjet printing is performed directly onto porous paper, then the process is simple, but the resolution is limited due to ink wicking and variation in print head to substrate distance
Solution Approach 1:
The intermediate transfer member with hydrophobic release layer and charged chemical agent treatment serves as a mediator between the inkjet print head and the porous substrate. It maintains a constant distance from the print head, prevents ink wicking by controlling droplet spread, and enables high-resolution printing while keeping the process relatively simple.
4Manufacturing precision
If coated substrates are used to control ink absorption, then image quality improves, but the substrate surface remains wet requiring additional drying steps
Solution Approach 1:
The patent extracts the drying function from the substrate and relocates it to the intermediate transfer member. The hydrophobic surface with charged chemical agent allows rapid evaporation of aqueous ink on the blanket before transfer, so the substrate receives pre-dried ink, eliminating the need for additional drying steps and reducing time loss.
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 enhances image quality by maintaining the pancake shape of ink droplets, reducing droplet contraction, and facilitating stable transfer to the substrate, resulting in higher optical density and improved printing performance.
Implementation Method 1
Surfactants and salts have been used to reduce the surface tension of the droplets of ink so that they do not bead as much
Implementation Method 2
Generally, silicone coated transfer members are preferred, since this facilitates transfer of the dried image to the final substrate. However, silicone is hydrophobic which causes the ink droplets to bead on the transfer member
Implementation Method 3
Generally, a substantial proportion or even all of the liquid is evaporated from the image on the intermediate transfer member, before the image is transferred to the final substrate
Data Source
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AI summary
The present application provides a method for treating a hydrophobic release layer of intermediate transfer member for use in a printing process in which a negatively charged aqueous inject ink including a polymeric resin and a colorant are jetted onto said layer, the claimed method comprising contacting the release layer, prior to jetting the ink, with a solution or dispersion in an aqueous solvent of a chemical agent which suppose to reduce the tendency of a jetted ink droplet that spreads on impinging upon the intermediate transfer member to bead under the action of the surface tension of the aqueous carrier of the ink Other embodiments, such as hydrophobic release layer and printed image on a substrate, are also described.