Layered material and process for preparing a layered material
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Solution Overview
Problem
Existing layer materials with capillaries or perforations are prone to moisture absorption, leading to unsightly surfaces, increased stiffness, and reduced strength due to heat and pressure, while lacking in water vapor permeability and ease of surface structuring, and often result in voids, bubbles, or cracks during drying.
Innovation Solution
A method involving a single layer of aqueous PU dispersions with a whipped foam structure, created using a mixture of aliphatic polyether, polyester, and polycarbonate polyurethane dispersions, which can be thermoplastically deformed for precise surface structuring without voids or cracks, maintaining water vapor permeability and preventing carrier layer hardening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a layered material with capillaries or perforations is used, then moisture can be absorbed, but this leads to unsightly surfaces, increased stiffness, and reduced strength
Solution Approach 1:
The patent employs a foamed PU layer with controlled porosity that allows water vapor permeability while preventing liquid moisture absorption. The foam structure provides the necessary permeability for breathability without creating the harmful capillary effects that lead to moisture uptake and surface defects in conventional perforated materials.
Solution Approach 2:
The patent creates a composite structure combining a textile carrier layer with a foamed PU coating layer. This composite approach allows the textile to provide structural integrity while the foamed PU layer provides surface structuring capability and controlled permeability, avoiding the strength losses associated with capillary-based moisture management systems.
2Manufacturing precision
If multiple layers are applied to achieve surface structuring, then surface appearance is improved, but layer separations and voids occur during drying
Solution Approach 1:
The patent combines multiple functional requirements into a single integrated foamed PU layer that provides both surface structuring and permeability control. By applying the PU dispersion and allowing it to foam in situ, the process ensures uniform distribution and bonding throughout the layer, eliminating the interface problems and voids that occur when multiple separate layers are applied and dried.
Solution Approach 2:
The patent utilizes the phase change and volume expansion characteristics of the PU dispersion during foaming. The dispersion transforms from a liquid state to a foamed structure with controlled cell formation, creating a homogeneous layer with integrated surface structure without the defects associated with conventional multi-layer drying processes.
3Manufacturing precision
If the carrier layer is pressed with high temperature during hot stamping, then surface structuring is achieved, but the carrier layer hardens and loses strength
Solution Approach 1:
The foamed PU layer acts as a thermal intermediary between the hot stamping die and the textile carrier layer. The foam structure provides thermal insulation that allows the die temperature to be maintained for effective surface structuring while preventing excessive heat transfer to the carrier layer, thereby avoiding carrier hardening and strength loss.
Solution Approach 2:
The porous foam structure inherently provides thermal insulation properties that mediate the heat transfer during hot stamping. This allows precise surface structuring at the PU layer interface while protecting the carrier layer from thermal damage, maintaining its mechanical properties.
4Area of stationary object
If a thick PU layer is applied to ensure coverage, then surface coverage is improved, but voids, sink marks, and bubbles form during drying
Solution Approach 1:
The patent exploits the volume expansion and cell formation characteristics of the foaming process to achieve uniform thick coatings without defects. As the PU dispersion foams, the gas bubbles create a cellular structure that prevents sink marks and promotes uniform drying throughout the thickness, eliminating the voids and bubbles that plague conventional thick non-foamed coatings.
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 solution provides a soft, water vapor-permeable layer material that can be easily structured and processed, maintaining mechanical properties and preventing carrier layer hardening, while reducing material usage and ensuring environmental sustainability.
Implementation Method 1
a) whipping a PU dispersion mixture (2)
Implementation Method 2
This requires only thermally activating the surface-structurable layer and thermoforming it above its softening point
Implementation Method 3
thermoforming it above its softening point using a die or embossing roller under heat and pressure
Implementation Method 4
the applied layer (3) is dried to a water content of less than 1.5 wt.%, preferably less than 0.5 wt.%, in particular until it is free of water
Data Source
Figure 1~2
AI summary
The invention relates to a method for producing a layered material, which has a substrate layer (1) and a layer (2) of polyurethane bonded to the substrate layer, wherein a leather, preferably a sanded grain leather, a textile material, preferably a woven fabric or a knitted fabric, a bonded leather material or a microfiber nonwoven is used as the substrate layer (1) and is bonded to the layer (2). According to the invention, at least one, preferably a single, layer of frothed polyurethane foam is applied to the substrate layer (1) as the layer (2).