Water-Based Photoresist for Multi-Layer Security Documents
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Solution Overview
Problem
Conventional methods for producing multi-layer bodies using solvent-based photoresists and wash varnishes face issues such as reduced quality due to solubility of additional lacquer layers, environmental unfriendliness, and limited resolution and edge sharpness due to porosity of wash varnishes.
Innovation Solution
A method utilizing a water-based photoresist that coats solvent-based lacquer layers without degrading their quality, allowing for higher resolution and edge sharpness, and is more environmentally friendly, with the water-based photoresist acting as a wash resist to remove unexposed areas using an acidic sodium metaperiodate solution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solvent-based photoresists and wash varnishes are used, then the desired removal function is achieved, but the additional lacquer layers are dissolved and the quality is reduced
Solution Approach 1:
The patent changes the chemical basis of the photoresist from solvent-based to water-based. This parameter change allows the photoresist to provide the necessary removal function while being compatible with solvent-based lacquer layers, preventing their dissolution and maintaining overall quality.
Solution Approach 2:
The water-based photoresist acts as an intermediary that bridges the incompatibility between water-soluble removal function and solvent-based lacquer layers. It provides the removal mechanism without attacking the solvent-based underlying layers.
2Reliability
If solvent-based paints are used, then the desired removal function is achieved, but they are not environmentally friendly and require complex disposal
Solution Approach 1:
The patent changes the solvent system from organic-based to water-based. This parameter change maintains the removal function while eliminating the environmental hazards and complex disposal requirements associated with solvent-based paints.
3Reliability
If wash varnishes are made highly pigmented and porous to ensure removal function, then the desired removal function is achieved, but the resolution and edge sharpness are limited
Solution Approach 1:
The patent changes the chemical composition of the wash varnish from highly pigmented and porous to less pigmented and less porous. This parameter change maintains the removal function through the water-based photoresist mechanism while significantly improving resolution and edge sharpness.
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 method achieves significantly improved resolution and edge sharpness, is more environmentally friendly, and allows for the creation of high-quality, attractive graphic designs in multi-layer bodies suitable for security elements like banknotes and product labels, with easier disposal and processing.
Implementation Method 1
When the first layer of lacquer is exposed, polymeric components of the lacquer cross-link, so that its molecular weight increases in the exposed first area.
Implementation Method 2
The paint in the unexposed second area can therefore be removed simply by washing with an aqueous solvent.
Data Source
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AI summary
The invention relates to a method for producing a multi-layer body comprising the steps of: a) applying a first coating layer made of a water-based photoresist onto a surface of a base body; b) exposing the first coating layer in a first region, wherein the first coating layer is not exposed in a second region; c) removing the first coating layer in the second region. The invention further relates to a multi-layer body obtainable by said method and to a security document comprising such a multi-layer body.