Water-Permeable Polyurethane Composite Moldings
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Solution Overview
Problem
Existing methods for producing moldings from granulated substrates and polyurethane compositions fail to achieve a balance between high mechanical strength and water permeability.
Innovation Solution
The production of moldings using a combination of mineral or plastic-containing granules and a 2-component polyurethane adhesive, where the adhesive consists of a polyol component with oleochemical polyols, diols, and trivalent or higher-functional polyols, and an isocyanate component, with a specific NCO/OH ratio, to create a crosslinked structure that allows for high water permeability and mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional polyurethane compositions are used to bond granulated substrates, then mechanical strength can be achieved, but water permeability is reduced
Solution Approach 1:
The patent applies porous materials by formulating the polyurethane composition to create a foam structure with controlled porosity. The composition includes blowing agents and foaming agents that generate cavities within the cured adhesive matrix, allowing water to permeate through while the granulated substrate provides structural strength. This resolves the contradiction by making the material itself porous rather than blocking water with a dense structure.
Solution Approach 2:
The patent creates a composite material system consisting of granulated substrates (mineral or plastic) bonded with polyurethane foam adhesive. The granules provide mechanical strength and structural integrity, while the foam-based adhesive provides water permeability through its cellular structure. This composite approach allows both requirements to be satisfied simultaneously by assigning different functions to different components.
2Strength
If high filler content is added to foam material to increase strength, then mechanical strength improves, but water permeability decreases
Solution Approach 1:
The patent applies local quality by carefully controlling the distribution and amount of filler within the foam matrix. Instead of uniformly high filler content throughout, the formulation allows the foam structure to maintain its permeable characteristics in critical areas while providing sufficient local reinforcement where granules are present. This selective approach preserves water permeability while achieving necessary strength.
Solution Approach 2:
The patent maintains porosity despite filler addition by using the foam expansion process to create interconnected voids around filler particles. The blowing agents generate gas bubbles that form a cellular structure, and even with filler present, the foam matrix retains sufficient pore connectivity to allow water permeability. The filler is incorporated into the foam structure rather than creating a dense composite.
3Stability of the object's composition
If 2-component polyurethane adhesive is used with specific NCO/OH ratio, then crosslinked structure provides mechanical stability, but may reduce water permeability
Solution Approach 1:
The patent applies parameter changes by optimizing the NCO/OH ratio within a specific range (1.0 to 2.0:1) to achieve the right balance between crosslinking density and porosity. The formulation also controls the molecular weight and functionality of polyols to regulate the curing process and final network structure. These parameter adjustments ensure sufficient crosslinking for mechanical stability while maintaining enough free volume for water permeability.
Solution Approach 2:
The patent ensures that even with crosslinked structure from 2-component adhesive, the foam morphology is preserved through controlled foaming during or after curing. The crosslinked network provides mechanical stability while the foam cavities, formed by blowing agents, maintain water permeability pathways. The two properties are decoupled by separating the structural function (crosslinked matrix) from the permeability function (foam voids).
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 resulting moldings exhibit high mechanical stability and water permeability, with compressive strength above 5 N/mm² and water permeability ranging from 500 to 3000 l/m² per minute, suitable for applications such as permeable surfaces and pathways.
Implementation Method 1
a 2-component polyurethane adhesive (B), where the adhesive consists of a polyol component (B1) and an isocyanate component (B2), in a ratio of the NCO/OH ratio of the polyisocyanates to the polyols of between 1.0 and 2.0:1
Data Source
AI summary
The invention relates to molded bodies composed of granules and 2-component polyurethane adhesives, containing A) 99% to 65% by weight of granules composed of mineral or synthetic substances with an average grain size of 0.5 mm to 100 mm, B) 1% to 35% by weight of a 2-component polyurethane adhesive consisting of a polyol component composed of 10% to 98% by weight of at least one oleochemical polyol, 1% to 50% by weight of at least one diol with a molecular weight of 60 g/mol to 2000 g/mol, 1% to 10% by weight of at least one three-, four-, or five-functional polyol with a molecular weight of 90 g/mol to 750 g/mol, 0% to 75% by weight of other additives, and one isocyanate component composed of at least one polyisocyanate, wherein the NCO/OH ratio of the isocyanate to the polyols ranges between 1.0 and 2.0:1. The invention further describes a method for the production of such molded bodies and selected suitable adhesives for the production of such molded bodies.