Partially Hydrolyzed EVA Copolymer Relief Precursor for Pad Printing
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Solution Overview
Problem
Existing relief precursors in pad printing, flexographic, and letterpress printing suffer from mechanical instability, curling issues, and decreased durability, leading to poor printing quality and increased susceptibility to cracking, which affects the reliability and precision of printed images.
Innovation Solution
A photosensitive composition comprising a partially hydrolyzed ethylene vinyl acetate copolymer with reduced -CH2-CH2- groups, combined with ethylenically unsaturated compounds and a photoinitiator system, enhances the flexibility and adhesion of the relief precursor, reducing curling and improving mechanical stability, allowing for faster manufacturing and better ink transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional photosensitive compositions are used in relief precursors, then the precursor can be manufactured and processed, but the resulting relief structures show decreased mechanical quality, cracking, and curling issues
Solution Approach 1:
The patent modifies the chemical composition parameters of the photosensitive layer by incorporating specific polymers (polyvinyl alcohol, polyvinyl acetate), plasticizers (phthalates, citrates, glycol esters), and adhesion promoters (silanes, titanates). These parameter changes in the material composition improve flexibility and reduce curling while maintaining mechanical stability during extended printing operations.
Solution Approach 2:
The invention uses composite material systems combining multiple components: polymers for structural integrity, plasticizers for flexibility, photoinitiators for curing, and adhesion promoters for bonding. This composite approach creates a balanced formulation that simultaneously addresses cracking, curling, and mechanical durability issues in relief printing plates.
2Manufacturing precision
If the washing step is extended to remove all uncured material, then complete development is achieved, but the manufacturing time increases significantly
Solution Approach 1:
The patent applies preliminary action by using photoinitiators that enable complete and rapid curing of the photosensitive composition during the exposure step. This ensures that all cured regions are fully polymerized before washing, allowing the washing process to be shortened while still achieving complete removal of uncured material and full development of the relief structure.
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 solution results in relief structures with improved elongation at break, reduced curling, and enhanced durability, leading to higher printing quality and longer run lengths without cracking, thereby addressing the mechanical and stability issues of previous precursors.
Implementation Method 1
the components crosslink or cure when they are exposed to electromagnetic radiation
Implementation Method 2
at least one photoinitiator or photoinitiator system as component P
Data Source
Figure 1~3B
AI summary
A photosensitive composition (L2) of a developable relief precursor, comprising: at least one copolymer as component C, at least one ethylenically unsaturated compound as component U, at least one photoinitiator or photoinitiator system as component P, at least one water soluble and/or water dispersible binder as component B, wherein the at least one copolymer as component C is an at least partially hydrolyzed ethylene vinyl acetate copolymer, comprising ―CH2-CH2― groups and wherein the content of said ―CH2-CH2― groups in the partially hydrolyzed ethylene vinyl acetate copolymer is lower than 20 mol%, preferably lower than 15 mol%, more preferably lower than 10 mol%.