Polyurethane Foam Skin Compatibility via Dispersion Mixing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Foamed articles, particularly those intended for wound dressings, face challenges with instability, brittleness, and cytotoxicity due to the use of conventional foam stabilizers, which are not skin-compatible and can lead to contamination and aesthetic issues.
Innovation Solution
A foamed article is produced by mixing two chemically distinct polyurethane dispersions (A and B), with specific compositions and reaction conditions to achieve high stability, tear resistance, and skin compatibility, while minimizing cytotoxic components, and using a manufacturing process that includes isocyanate-functional prepolymers, polyols, and hydrophilizing agents to create a non-cytotoxic and crack-free foam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional foam stabilizers are used to produce stable foam, then foam stability is improved, but skin compatibility deteriorates and cytotoxicity increases
Solution Approach 1:
The patent changes the chemical composition parameters of the foam stabilizer by using polyol-based stabilizers with specific molecular weights (400-8000 g/mol) and hydroxyl values (1.5-6 mg KOH/g) instead of conventional cytotoxic stabilizers. This parameter change achieves both foam stability and skin compatibility simultaneously
Solution Approach 2:
The patent creates a composite foam system combining polyurethane dispersion with specific polyol stabilizers and hydrophilizing agents. This composite approach allows the foam to achieve stability through the polyol-based stabilizer while maintaining skin compatibility through the selected chemical composition and controlled hydrophilicity
2Strength
If foam is made more flexible to reduce brittleness, then crack formation is reduced, but foam stability deteriorates
Solution Approach 1:
The patent optimizes the molecular weight and hydroxyl value parameters of the polyol stabilizer to achieve the right balance between flexibility and stability. By controlling these parameters, the foam achieves sufficient tear resistance without compromising stability
Solution Approach 2:
The patent uses hydrophilizing agents that replicate the stabilizing effect of conventional additives but with skin-compatible chemistry. These agents provide the necessary foam stability while allowing the foam to be flexible and crack-free, effectively copying the stabilizing function without the harmful side effects
3Object-affected harmful factors
If foam stabilizers with high skin compatibility are used, then cytotoxicity is reduced, but foam stability deteriorates
Solution Approach 1:
The patent identifies and optimizes specific parameter ranges for polyol-based stabilizers (molecular weight 400-8000 g/mol, hydroxyl values 1.5-6 mg KOH/g) that simultaneously achieve both skin compatibility and foam stability. This precise parameter control resolves the contradiction between safety and stability
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 foamed article exhibits high stability, tear resistance, and excellent skin compatibility with minimal toxic components, ensuring improved safety and performance as a wound dressing or hygiene article.
Implementation Method 1
isocyanate-functional prepolymers from A1) organic polyisocyanates, A2) polymeric polyols with number-average molecular weights of 400 to 8000 g/mol, preferably 400 to 6000 g/mol, or more preferably 600 to 3000 g/mol, and OH functionalities of 1.5 to 6, more preferably 1.8 to 3, or more preferably 1.9 to 2.1
Implementation Method 2
foaming and subsequent drying of the mixture
Implementation Method 3
foaming and subsequent drying of the mixture
Data Source
AI summary
The invention relates to a foamed, fissure-free skin-compatible article, produced by mixing a first polyurethane dispersion (A) with at least one second polyurethane dispersion (B) which differs from the first polyurethane dispersion (A), optionally with the addition of other additives, then by foaming and subsequently drying the mixture. The invention also relates to a process for preparing the foamed article and to the use thereof.