Decorated Natural Leather Barrier Layer for Monomer Control
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Solution Overview
Problem
Existing methods for decorating natural leather using UV curable inkjet inks face challenges such as high residual uncured monomers, poor image quality with aqueous inks, and ineffective barrier layers, leading to health risks and flexibility issues in leather products.
Innovation Solution
The use of a barrier layer containing a thiol polymer with a molecular weight of at least 500 g/mol on both the basecoat and topcoat of natural leather, which reduces the extractability of compounds like acrylate monomers, vinyl methyl oxazolidinone, and photodecomposition products like mesitaldehyde, enhancing flexibility and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If UV curable inkjet inks with high amount of monofunctional monomers are used to ensure flexibility, then flexibility is improved, but residual uncured monomers increase posing health and safety risks
Solution Approach 1:
A barrier layer comprising a polyvinyl amine-polyvinyl alcohol copolymer is introduced as an intermediary between the printed leather and the environment. This barrier layer selectively allows water vapor to pass through while blocking the migration of uncured monomers and other harmful substances, thus maintaining flexibility while reducing health and safety risks
Solution Approach 2:
The patent applies a thin film barrier layer that maintains the flexibility of the leather while providing protective functionality. The barrier layer is designed to be flexible enough to accommodate the natural movement of leather products while effectively preventing the migration of harmful substances
2Object-generated harmful factors
If aqueous inkjet inks are used to reduce residual monomers, then health and safety is improved, but image quality deteriorates on crusted leather
Solution Approach 1:
The barrier layer acts as an intermediary that allows the use of UV curable inks (which provide good image quality) while preventing the migration of harmful substances. It mediates between the requirements for good image quality and health and safety by selectively blocking harmful components without affecting the visual properties of the printed image
3Object-generated harmful factors
If polyfunctional monomers are increased to reduce residual uncured monomers, then health and safety is improved, but flexibility is reduced leading to cracks
Solution Approach 1:
Instead of modifying the ink composition to reduce residual monomers, the patent introduces a barrier layer as an intermediary that prevents the migration of uncured monomers from the printed leather. This approach maintains the flexibility provided by monofunctional monomers while effectively reducing health and safety risks through the barrier layer's selective blocking properties
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 solution effectively reduces the extractability of harmful compounds from natural leather, improving its flexibility and safety while maintaining image quality, addressing the limitations of previous methods.
Implementation Method 1
a barrier layer containing a thiol polymer having a molecular weight of at least 500 g/mol is present on the basecoat and/or in the topcoat
Implementation Method 2
UV curable inkjet inks have the advantage that they can also be printed on substantially non-absorbing substrates
Data Source
Figure 1~2
Figure 3~3E
AI summary
A decorated natural leather having a decorative image inkjet printed with radiation curable inkjet inks on a crusted leather having a pigmented basecoat on the grain side of the crusted leather, wherein the decorative image is covered by a topcoat and wherein a barrier layer containing a thiol polymer having a molecular weight of at least 500 g/mol is present on the basecoat and/or in the topcoat. A method for manufacturing the decorated natural leather is also disclosed.