Dual Imaging Layer Lithographic Plates for Red-Spot Reduction
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Solution Overview
Problem
Current laser-based lithographic systems face challenges in imaging speed and plate durability due to the limitations of nitrocellulose-based ablation layers, which can lead to red-spot formation and decreased performance when combined with IR-absorbing dyes, especially at high temperatures and with elemental metals.
Innovation Solution
The use of dual adjacent imaging layers, one containing nitrocellulose and the other an IR-absorptive pigment without a dye, along with a binder like melamine resin, allows for high loading of IR-absorbing dyes without impairing layer durability, and the nitrocellulose is kept in a separate, crosslinked layer to prevent deleterious interactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If nitrocellulose is combined with IR-absorbing dyes in the same layer to increase imaging speed, then the plate can be imaged faster, but red-spot formation occurs and layer durability decreases
Solution Approach 1:
The imaging layer is divided into two separate layers: a first imaging layer containing nitrocellulose and an IR-absorbing pigment, and a second imaging layer containing an IR-absorbing dye. This segmentation prevents the harmful interaction between nitrocellulose and IR-absorbing dyes that causes red-spot formation, while both layers contribute to imaging speed. The patent states: 'The first and second imaging layers can be imaged simultaneously or sequentially to carry out imaging at high speeds'
Solution Approach 2:
An IR-absorbing pigment (such as carbon black) is used in the first imaging layer as an intermediary that absorbs IR radiation without causing the deleterious effects of IR-absorbing dyes on nitrocellulose. The pigment enables efficient energy absorption for fast imaging while maintaining layer durability. The patent explains: 'the first imaging layer comprises a binder and a near-IR absorber including a pigment... the second imaging layer comprises nitrocellulose and a near-IR absorber that does not include a pigment'
2Productivity
If high laser power is used to increase beam fluence and improve imaging speed, then imaging can be carried out faster, but the plate may be damaged beyond intended ablation results
Solution Approach 1:
The patent modifies the compositional parameters of the imaging layers to achieve optimal ablation sensitivity. By formulating the first layer with nitrocellulose and IR-absorbing pigment, and the second layer with IR-absorbing dye, the plate becomes highly responsive to laser irradiation at controlled fluence levels. This allows fast imaging without excessive laser power that could cause damage. The patent states: 'The first and second imaging layers are at least partially ablatabile by exposure to near-IR radiation'
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
This configuration enhances the performance of nitrocellulose-containing lithographic printing members by reducing red-spot areas, maintaining high imaging speeds, and ensuring layer durability, allowing for efficient imaging with reduced laser power and improved plate longevity.
Implementation Method 1
exposing the printing member to imaging radiation in an imagewise pattern, the imaging radiation at least partially ablating the imaging layers where exposed
Implementation Method 2
Exposure to laser radiation (typically in the near-infrared (IR) range) may, for example, cause ablation— i.e., catastrophic overheating— of the ablated layer
Implementation Method 3
the necessary ink-repellency is provided by an initial application of a dampening fluid to the plate prior to inking... Exposure to laser radiation (typically in the near-infrared (IR) range) may, for example, cause ablation— i.e., catastrophic overheating
Data Source
AI summary
Dry, ablation-type, nitrocellulose-containing lithographic printing members (100) include dual adjacent imaging layers (104, 106), both including an absorber and at least one containing a binder (which may include or consist essentially of a melamine resin). The absorber of the nitrocellulose-containing layer is a pigment and this layer contains no absorbing dye, while the absorber of the other imaging layer includes or consists essentially of a dye.