Polyurethane Back Coating for Offset Printing Adhesion
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Solution Overview
Problem
Existing heat-sensitive recording materials face challenges with back coatings that are not resistant enough to water during offset printing, leading to adhesive issues and deposits on printing blankets, which complicates the printing process and results in poor printability.
Innovation Solution
A heat-sensitive recording material with a polyurethane-based back coating that acts as a crosslinking agent, providing excellent resistance to water and preventing deposits on printing blankets, while maintaining stability and non-reactivity with the pH of the coating color, allowing for effective offset and flexographic printing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional back coating is used to prevent plasticizer penetration, then barrier effect against chemicals is improved, but printability deteriorates due to deposits on printing blankets
Solution Approach 1:
The patent modifies the chemical composition parameters of the back coating by incorporating specific polymers (polyvinyl alcohol, carboxymethyl cellulose, starch) and crosslinking agents (glyoxal, glutaraldehyde) to achieve optimal balance between barrier properties and printability. The crosslinking degree and polymer ratios are adjusted to prevent both chemical penetration and printing defects
Solution Approach 2:
The back coating is formulated as a composite material system combining multiple polymer types (water-soluble and water-insoluble), crosslinking agents, and optional additives. This composite structure provides synergistic effects where the polymer matrix offers barrier protection while the crosslinked network prevents adhesive issues during printing
2Strength
If back coating resistance to water is increased, then adhesive issues are reduced, but printing process complexity increases due to blanket deposits
Solution Approach 1:
The back coating formulation includes water-soluble polymers that provide self-regulating adhesive properties. The coating naturally resists water-based offset printing inks and solvents without requiring additional protective layers or complex printing process modifications, allowing standard printing equipment to operate without special adjustments
3Manufacturing precision
If additional protective layers are added to improve printability, then surface quality is improved, but device complexity increases
Solution Approach 1:
The back coating is designed as a multi-functional layer that simultaneously provides: (1) barrier protection against plasticizers and chemicals, (2) adhesive resistance during water-based offset printing, (3) prevention of blanket deposits, and (4) good printability. This consolidation of multiple functions into a single layer eliminates the need for additional protective coatings
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 polyurethane-based back coating ensures stable and long-lasting printability, preventing adhesive issues and maintaining surface quality, allowing for high-quality printing without the need for additional protective layers, and is environmentally safe.
Implementation Method 1
a polyurethane-based component which acts as a crosslinking agent
Implementation Method 2
the back coating has a good barrier effect against the substances used in offset and flexographic printing, especially organic solvents, as well as against plasticizers, oils, and fats
Data Source
AI summary
A thermosensitive recording material comprising a substrate, a thermosensitive recording layer applied to the front and a back coating which comprises a polyurethane-based-cross-linking component in addition to pigments and binders.