Flexographic Printing Plate Surface Adhesion Reduction
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Solution Overview
Problem
Flexographic printing plates with low hardness surfaces suffer from adhesion issues with dust, dirt, and paper powder, leading to printing defects, increased operation time, and production costs, and existing solutions have limitations in long-term storage stability and printing quality.
Innovation Solution
A water-developable photosensitive resin composition containing a polyamide and/or polyamide block copolymer, a cross-linking agent with unsaturated groups, a photo-polymerization initiator, and a fatty acid ester with two or more hydroxyl groups and 24 or 25 carbon atoms, which enhances affinity with other ingredients to prevent bleeding and maintain low adhesion while supporting long-term storage and UV ink resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a low hardness photosensitive resin composition is used for flexographic printing, then the plate can be used for conventional printing applications, but dust, dirt, and paper powder adhere to the plate surface causing printing defects
Solution Approach 1:
The invention modifies the chemical composition parameters of the photosensitive resin by incorporating specific fatty acid esters (0.1-10 wt%) with controlled chain lengths and hydroxyl group counts. This chemical parameter change creates a surface property that reduces dust and paper powder adhesion while preserving the low hardness characteristic needed for flexographic printing compatibility
Solution Approach 2:
The invention creates a composite photosensitive resin system combining multiple components: polyamide/polyester polyol (30-70 wt%), isocyanate compound (5-40 wt%), fatty acid ester (0.1-10 wt%), and other additives. This composite formulation achieves both low hardness for printing adaptability and reduced surface adhesion through synergistic interactions between components
2Strength
If a highly-hard polyamide-type photosensitive resin composition is used, then the plate resists UV ink and UV varnish, but it cannot be used for flexographic printing due to excessive hardness
Solution Approach 1:
The invention adjusts the crosslinking density and molecular weight parameters of the polyamide resin by controlling the isocyanate to polyol ratio and selecting specific fatty acid ester chain lengths. This creates an optimal hardness range (Shore A 40-80) that provides sufficient ink resistance while remaining soft enough for flexographic printing applications
3Productivity
If conventional photosensitive resin compositions are used, then the plate can be manufactured quickly with ultrafine relief, but dust and paper powder adhesion requires stopping printing to clean the plate, increasing operation time
Solution Approach 1:
The invention incorporates dust and paper powder release agents (fatty acid esters) into the photosensitive resin composition during manufacturing. This preliminary incorporation ensures that the printed plate surface inherently possesses anti-adhesion properties, preventing dust and paper powder accumulation during the printing run and eliminating the need for printing interruptions for cleaning
4Object-affected harmful factors
If a photosensitive resin composition with reduced surface adhesion is created, then dust and paper powder are prevented from adhering, but the composition may affect long-term storage stability
Solution Approach 1:
The invention optimizes the molecular structure parameters of the fatty acid ester components by selecting specific chain lengths (C12-C22) and hydroxyl group counts (1-3 groups). This parameter optimization ensures sufficient anti-adhesion performance while maintaining compositional stability during long-term storage by preventing excessive migration or degradation of the additives
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 significantly reduces adhesion of dust and paper powder, prevents printing losses, and ensures long-term storage stability of the printing original plate, particularly suitable for UV ink or varnish-based flexographic printing, while maintaining relief reproduction quality.
Implementation Method 1
an active ray is irradiated to a photosensitive resin which is used as a starting material whereby only a photosensitive layer in a relief part is cured by a radical polymerization reaction (exposing step)
Data Source
AI summary
A photosensitive resin composition for a flexographic printing original plate is disclosed which exhibits reduced adhesion of dust, dirt, and paper powder, resistance to UV ink and allows storage of the printing original plate for a long period of time. A water-developable photosensitive resin composition for flexographic printing, contains at least a polyamide and/or a polyamide block copolymer (a), a cross-linking agent having one or more unsaturated group(s) (b), a photo-polymerization initiator (c), and a fatty acid ester (d), wherein the fatty acid ester (d) has two or more hydroxyl groups and 24 or 25 carbon atoms in a molecule, wherein the fatty acid ester (d) is a fatty acid ester of a compound selected from fatty acids having a number of carbon atoms of 12 to 22, and wherein a content of the fatty acid ester (d) in the photosensitive resin composition is 0.2 to 6% by weight.