Colorless Varnish for Digital Printing Adhesion
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Solution Overview
Problem
Digital printing technologies, such as liquid electrophotographic (LEP) printing, face challenges in achieving durable prints against mechanical wear, as they often suffer from low adhesion and vulnerability to peeling and rubbing due to the presence of non-polar carrier fluids in the printed layers.
Innovation Solution
A colorless varnish is developed, comprising a dispersion of solid polar compounds in a resin, which reduces the amount of non-polar carrier fluid and enhances mechanical strength by acting as a protective layer over the underlying ink, including components like maltose monohydrate and charge adjuvants to improve charge conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If non-polar carrier fluids are used in LEP printing, then the ink can be transferred effectively, but the printed layers have low adhesion and high vulnerability to peeling and rubbing
Solution Approach 1:
The patent uses a composite material consisting of polar resin particles dispersed in non-polar carrier fluid. The polar resin forms a continuous network that provides strong adhesion to the substrate, while the non-polar carrier fluid enables effective ink transfer. This composite structure resolves the contradiction by combining materials with complementary properties to achieve both effective transfer and strong adhesion.
Solution Approach 2:
The patent changes the physical and chemical parameters of the printed layer by controlling the particle size distribution of the polar resin (0.1-10 micrometers) and the concentration of polar compounds (20-80% by weight). These parameter changes optimize the balance between adhesion strength and resistance to mechanical wear, transforming the vulnerable printed layer into a durable coating.
2Strength
If solid polar compounds are dispersed in resin, then mechanical strength and adhesion are enhanced, but the complexity of the varnish composition increases
Solution Approach 1:
The patent segments the varnish composition into distinct functional components: polar resin particles (adhesion provider), non-polar carrier fluid (transfer medium), and optional charge adjuvants (electrostatic property modifier). Each component performs a specific function, allowing for optimized performance while maintaining compositional clarity. This segmentation resolves the complexity issue by organizing the composite material into manageable, functionally-defined segments.
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 colorless varnish significantly increases the durability of LEP prints by enhancing adhesion and resistance to mechanical wear, as demonstrated by improved peeling and rubbing tests, with the solid polar compounds dispersed in the resin forming a robust protective layer.
Implementation Method 1
a dispersion of solid polar compounds in a resin
Implementation Method 2
solid polar compounds dispersed in the resin of the colorless paste
Implementation Method 3
The colorless varnish also includes a charge adjuvant and a charge director, which impart charges to the colorless varnish
Implementation Method 4
an ink image is electrostatically transferred from a photo imaging plate (i.e., photoconductor, photoconductive drum, photoreceptor, etc.) to an intermediate drum or roller
Data Source
AI summary
A colorless varnish for digital printing includes a colorless paste, which is made up of anon-polar carrier fluid and a resin swollen in the non-polar carrier fluid. The resin is present in the paste in an amount ranging from about 20% (w/w) to about 50% (w/w). A solid polar compound is dispersed in the resin. The solid polar compound is present in an amount up to 60 wt. % of solids in the colorless paste.