Printing Form Precursor with Infrared Ablation Layer
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Solution Overview
Problem
Current flexographic printing technologies face challenges in achieving uniform, dense ink coverage in solid areas, particularly with digital workflows, which often result in dot sharpening effects and reduced ink density due to oxygen inhibition during photopolymerization, leading to print defects like mottle and graininess.
Innovation Solution
A photosensitive printing form precursor is developed, comprising a photopolymerizable layer, an infrared ablation layer, and a pattern layer with features opaque to actinic radiation but transparent to infrared radiation, allowing for imagewise exposure and treatment to create a relief surface with improved ink transfer characteristics without the need for high-resolution digital imaging equipment or complex workflows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If digital workflow with laser ablation is used to create in-situ mask, then ease of operation and productivity are improved, but manufacturing precision deteriorates due to dot sharpening effect and reduced ink density
Solution Approach 1:
The patent applies preliminary action by pre-forming a microcell pattern on the photopolymerizable layer before the laser ablation process. This microcell pattern serves as a template that guides the subsequent laser ablation to create the in-situ mask, ensuring that the relief structure formed maintains uniform ink density and avoids dot sharpening effects while still benefiting from the ease of digital workflow operation.
2Productivity
If conventional digital workflow is used, then productivity is improved, but manufacturing precision worsens due to oxygen inhibition during photopolymerization
Solution Approach 1:
The patent applies inert atmosphere by conducting the photopolymerization process in an oxygen-free or oxygen-limited environment. This prevents oxygen inhibition during photopolymerization, ensuring that the relief structure formed has the desired quality with uniform ink density and proper dot characteristics, while maintaining the high productivity of digital workflow.
3Manufacturing precision
If high-resolution digital imaging equipment is used to avoid dot sharpening, then manufacturing precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses preliminary action by pre-forming a microcell pattern that serves as a template for the laser ablation process. This allows the use of standard digital imaging equipment at lower resolutions, as the microcell pattern guides the laser to create the precise relief structure needed, thereby avoiding the need for expensive high-resolution equipment while maintaining manufacturing precision.
4Manufacturing precision
If analog workflow with phototool is used, then manufacturing precision is maintained, but device complexity and time consumption increase
Solution Approach 1:
The patent extracts the essential function of the phototool (creating the mask pattern) and integrates it directly into the photopolymerizable layer through the microcell pattern and laser ablation process. This eliminates the need for separate phototool preparation and handling, reducing process complexity while maintaining the manufacturing precision and print quality associated with analog workflows.
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 enables the production of relief printing forms with enhanced solid ink density and print quality, maintaining high resolution and productivity while avoiding the dot sharpening effects associated with conventional digital workflows, and supports the printing of full tonal ranges including fine print elements and highlight dots.
Implementation Method 1
The actinic radiation enters the photosensitive element through the clear areas and is blocked from entering the black or opaque areas of the transparency or in-situ mask. The areas of the photopolymerizable layer that were exposed to the actinic radiation crosslink and harden
Implementation Method 2
The infrared-sensitive layer is imagewise exposed with laser radiation of a digital imager unit whereby the infrared-sensitive material is removed from, or transferred onto/from a superposed film of the assemblage, to form the in-situ mask having radiation opaque areas and clear areas
Data Source
AI summary
The invention pertains to a photosensitive element, particularly a photopolymerizable printing form precursor; a method of preparing the photosensitive element to form a printing form for use in relief printing; and, a process of making the photosensitive element. The printing form precursor includes a layer of a photosensitive composition, a digital layer that is adjacent to a side of the photosensitive layer, and a cell pattern layer that is disposed between the photosensitive layer and the digital layer. The cell pattern layer includes a plurality of features in which each feature an area between 5 to 750 square microns and is composed of an ink that is opaque to actinic radiation and transparent to infrared radiation. Since the cell pattern layer is integral with the printing form precursor, digital imaging can occur rapidly with relatively low resolution optics to form a mask without needing to also form a microcell pattern of the digital layer. The printing form precursor having the integrated cell pattern layer facilitates the preparation of relief printing forms to have a print surface suitable for printing solids with uniform, dense coverage of ink.