Two-Step Primer Application for LEP Ink Transfer
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Solution Overview
Problem
Existing electrophotographic printing processes face challenges in achieving efficient ink transfer onto print substrates, particularly on difficult-to-print materials like cardboard, due to inadequate primer coatings, leading to defects and increased issues with print quality over time.
Innovation Solution
A method involving a two-step primer application process, where a first primer is coated onto the substrate using an analogue technique and a second primer is digitally printed on top, utilizing a first primer resin with carboxylic or amine functional groups and a second primer resin with a solid polar compound and non-polar carrier, enhancing ink adhesion and transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single primer coating is applied to the print substrate, then the printing process is simpler and faster, but ink transfer efficiency deteriorates leading to print defects
Solution Approach 1:
The primer application is divided into two distinct steps: first applying a base primer coating to the substrate, then applying a second primer coating over it. This segmentation allows each primer layer to perform specific functions - the first primer provides foundational adhesion while the second primer optimizes ink transfer properties, thereby resolving the contradiction between simplified single-step application and effective multi-functional performance.
Solution Approach 2:
The first primer coating is applied in advance to prepare the substrate surface before the second primer and subsequent ink application. This preliminary action modifies the substrate surface properties to enhance adhesion and create an optimal base for the second primer, ensuring that when the ink is applied, transfer efficiency is maximized without requiring complex single-step solutions.
2Device complexity
If a single primer coating is used, then the process is less complex, but print quality deteriorates over extended print runs
Solution Approach 1:
By dividing the primer system into two separate coatings with distinct compositions and functions, the patent achieves consistent print quality across extended runs. The first primer provides stable base adhesion while the second primer ensures consistent ink transfer properties, and this functional segmentation maintains quality uniformity without requiring overly complex application equipment.
Solution Approach 2:
The patent employs composite primer coatings where the first primer and second primer have different material compositions optimized for their respective functions. This composite approach - using materials with complementary properties rather than a single complex material - achieves durable, consistent print quality across extended production runs while keeping the application process manageable.
3Quantity of substance
If inadequate primer coating is applied, then material usage is reduced, but ink adhesion deteriorates leading to defects
Solution Approach 1:
The primer system is segmented into two functional layers that together provide sufficient total coverage and adhesion. The first primer layer establishes baseline adhesion with the substrate, while the second primer layer provides the additional bonding necessary for reliable ink attachment. This segmentation allows optimized material distribution where each layer contributes differently to overall adhesion, achieving reliable ink bonding without excessive material consumption.
Solution Approach 2:
The patent changes the parameters of primer application by using two primers with different chemical compositions and properties rather than a single primer. The first primer may have properties optimized for substrate penetration and bonding, while the second primer has properties optimized for ink interaction. This parameter differentiation allows efficient material usage where each primer contributes its specific strengths to achieve reliable adhesion.
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
This approach significantly improves ink transfer and print quality, reducing defects and maintaining substrate readiness for extended print runs, as demonstrated by improved image quality and reduced ink missing rates compared to single primer methods.
Implementation Method 1
the first primer resin comprising a carboxylic functional group, an amine functional group or a polyol functional group
Implementation Method 2
The charged toner particles adhere to the image areas of the latent image while the background areas remain clean
Implementation Method 3
which is often heated to fuse the solid image and evaporate the liquid carrier
Data Source
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AI summary
Described herein is a method for priming a print substrate for subsequently receiving a liquid electrophotographic (LEP) inkin which a surface of a print substrate is coated with a first primer using an analogue printing technique and a second primer is digitally printed to the surface of the print substrate coated with the first primer.