Polyurethane Reactive Melt Sealing Layer for Rapid Curing
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Solution Overview
Problem
Existing sealing methods using UV-curing and reactive polyurethane-based coatings require multiple layers and long curing times, limiting processing and packaging options due to mechanical complexity and space requirements.
Innovation Solution
A method involving a single application of a water-free and solvent-free polyurethane-based reactive melt layer, followed by a thin coating layer, which allows for concealed curing and reduces the need for multiple applications, with optional smoothing using a release agent to prevent sticking and enhance surface smoothness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If UV-curing coating materials are applied to seal article surfaces, then the sealing layer can be applied in multiple layers with good moisture resistance and cleaning product resistance, but the mechanical complexity and space requirements become very high
Solution Approach 1:
The patent combines the reactive melt layer and coating layer into a single integrated sealing system. The reactive melt layer provides the base sealing with moisture resistance, while the coating layer applied afterward provides additional protection and aesthetic qualities. This merging eliminates the need for separate UV-curing systems and multiple complex application steps while maintaining the desired protective properties.
Solution Approach 2:
The patent changes the curing mechanism from UV-light based to moisture-based curing. The reactive melt layer cures through reaction with atmospheric moisture, eliminating the need for UV lamps and complex curing chambers. This parameter change in the curing mechanism significantly reduces the mechanical complexity and space requirements while maintaining sealing effectiveness.
2Ease of manufacture
If reactive polyurethane-based melt layers are applied for sealing, then the desired layer thicknesses can be applied in one operation with sufficient flexibility to avoid brittle cracks, but the residence time before crosslinking and complete curing becomes very long
Solution Approach 1:
The patent segments the sealing process into two distinct stages: first applying the reactive melt layer that provides base sealing and flexibility, then applying a coating layer that provides additional protection and can be applied relatively quickly. This segmentation allows each layer to perform its specific function optimally while reducing the total time required compared to a single long-curing reactive melt application.
Solution Approach 2:
The reactive melt layer is applied and allowed to partially cure or remain in a semi-cured state while the coating layer is applied on top. This preliminary action of applying the reactive melt layer first creates a stable base that prevents brittle cracks and allows subsequent coating application without requiring the entire sealing system to wait for complete curing of the reactive melt.
3Reliability
If multiple layers of coating material are applied to achieve sufficient sealing, then the sealing performance is improved, but the number of applications and processing steps increases
Solution Approach 1:
The patent merges the functions of multiple coating applications into a two-layer system: the reactive melt layer provides the foundational sealing performance, and the coating layer provides additional protection and aesthetic qualities. This merging achieves comparable or superior sealing performance to multiple coating applications while requiring far fewer processing steps and applications.
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 approach enables a single-ply sealing with rapid curing and processing, maintaining the benefits of reactive melt layers while minimizing time and space requirements, and allowing for immediate further processing or packaging.
Implementation Method 1
the reactive melt is able to cure despite being concealed, by the coating layer, from the ambient air, whose moisture is typically needed for crosslinking and hence for curing
Implementation Method 2
the roll surface is provided with a release agent based on paraffin wax
Data Source
AI summary
The present invention relates to an article whose surface has been at least partly sealed and to methods of its sealing, the sealing layer comprising a reactive melt layer and a coating layer. The invention provides a method of sealing at least part of the surface of an article, comprising the steps of: (a) applying a reactive melt layer based on polyurethane to at least one part of the surface of the article; (b) smoothing the reactive melt layer; and (c) applying a coating material to form a coating layer on the reactive melt layer, the coating layer being applied before the full curing of the reactive melt layer.