Laminated Flexographic Printing Sleeve Barrier Layer
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Solution Overview
Problem
Cylindrical flexographic relief image printing elements face challenges in achieving improved image fidelity, solid ink density, and desired geometric characteristics, such as planarity, shoulder angle, and edge sharpness, which are not adequately addressed in existing technologies.
Innovation Solution
A method involving a digital platemaking process with a laser ablatable mask layer, a barrier layer, and actinic radiation exposure to create relief dots, where the barrier layer limits oxygen diffusion and imparts specific geometric characteristics to the printing dots, including a planar top surface, beneficial shoulder angle, and sharp edges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional flexographic printing plates are used, then the printing process is simple and durable, but the image fidelity and geometric characteristics are insufficient
Solution Approach 1:
The printing plate is divided into multiple functional layers: support layer, first photocurable layer, second photocurable layer, and laser ablatable mask layer. Each layer serves a specific function in achieving the desired geometric characteristics and image fidelity through selective exposure and ablation processes.
Solution Approach 2:
The invention transitions from traditional 2D flat plate imaging to 3D relief dot formation with controlled geometry. By using sequential photocurable layers and laser ablation, the process creates raised relief dots with specific geometric characteristics (planarity, shoulder angle, edge sharpness) that add a dimensional aspect to the printing surface.
2Productivity
If traditional chemical development is used, then the relief image is formed, but the processing time is long and chemical waste is generated
Solution Approach 1:
The invention replaces the chemical development process with a mechanical/thermal ablation process. A laser ablates the mask layer and selectively removes uncured photocurable material through heat and mechanical vaporization, eliminating the need for chemical developers and reducing processing time.
Solution Approach 2:
The process changes from chemical-based development to thermal/energy-based ablation. By controlling laser parameters (power, speed, wavelength) and exposure conditions, the uncured photocurable material is selectively removed through thermal decomposition and vaporization, achieving development without chemicals.
3Manufacturing precision
If the photocurable layer is exposed without a barrier layer, then the exposure process is simple, but the oxygen diffusion prevents proper curing and dot geometry
Solution Approach 1:
A barrier layer is introduced as an intermediary between the laser source and the photocurable layers. This barrier layer selectively transmits actinic radiation needed for curing while blocking oxygen diffusion to the exposed areas, enabling proper polymerization and controlling the geometric characteristics of the relief dots.
Solution Approach 2:
The barrier layer creates an oxygen-excluded environment during exposure, similar to an inert atmosphere. By preventing oxygen contact with the exposed photocurable material, the barrier layer enables complete polymerization and controls the curing depth and geometry of the relief dots.
4Manufacturing precision
If the support layer is made from flexible polymer materials, then the plate is flexible and durable, but the surface planarity and edge sharpness are compromised
Solution Approach 1:
The support function is separated from the image formation function. The support layer provides flexibility and durability, while the layered photocurable structure and laser ablation process independently create the precise geometric characteristics of the relief dots, allowing each function to be optimized separately.
Solution Approach 2:
The invention creates relief dots with controlled 3D geometry (planarity, shoulder angle, depth) through selective ablation of the mask layer and photocurable layers. This dimensional control compensates for the flexibility of the polymer support layer, ensuring sharp edges and planar surfaces despite the underlying material's flexibility.
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 method produces printing dots with enhanced geometric characteristics, leading to improved image fidelity and solid ink density, and allows for quicker processing without the need for chemical development, enhancing the efficiency and quality of cylindrical relief image printing.
Implementation Method 1
laser ablating the laser ablatable mask layer to create an in situ negative in the laser ablatable mask layer
Implementation Method 2
The photocurable layer(s) can include any of the known photopolymers, monomers, initiators, reactive or non-reactive diluents, fillers, and dyes. The term 'photocurable' refers to a composition which undergoes polymerization, cross-linking, or any other curing or hardening reaction in response to actinic radiation
Implementation Method 3
the barrier layer limits oxygen diffusion
Data Source
AI summary
A method of tailoring the shape of a plurality of relief dots created in a photosensitive printing blank during a digital platemaking process is provided. The photosensitive printing blank comprises a laser ablatable mask layer disposed on at least one photocurable layer which is mountable on a printing sleeve. The method comprises the steps of (1) laser ablating the laser ablatable mask layer to create an in situ negative in the laser ablatable layer; (2) placing a barrier layer on top of the laser ablatable mask layer; (3) exposing the at least one photocurable layer to actinic radiation through the barrier layer and the in situ negative; (4) removing the barrier layer; and (5) developing the imaged and exposed photosensitive printing blank to reveal the relief image therein, the relief image comprising the plurality of relief dots. The presence of the barrier layer produces printing dots having desired geometric characteristics.