Moisture-Permeable Composite Membrane Using Polyisoprene and Polyurethane
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Solution Overview
Problem
Existing waterproof and breathable textiles made from petrochemical raw materials lack the necessary elasticity and stretch for comfortable daily wear, and they also contribute to greenhouse gas emissions. Additionally, natural rubber-based materials are not moisture-permeable and can cause allergic reactions.
Innovation Solution
A moisture-permeable composite membrane is developed by crosslinking a mixture of polyisoprene, polyurethane with a polar functional group, a crosslinking agent, and a vulcanizing agent, with a weight ratio of polyurethane to polyisoprene ranging from 1:0.55 to 1:6.60, and applying the mixture to a release substrate for drying and crosslinking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If petrochemical raw materials are used to make waterproof and breathable textiles, then waterproofing and micro-elasticity are provided, but the necessary elasticity and stretch for comfortable daily wear are insufficient
Solution Approach 1:
The patent uses a composite material system consisting of polyisoprene (natural rubber) as the base polymer combined with polyurethane containing polar functional groups. This composite structure integrates the waterproofing properties of the crosslinked polyisoprene network with the elasticity and stretch characteristics of the polyurethane component, resolving the contradiction between waterproof strength and wear comfort.
Solution Approach 2:
The patent modifies the chemical structure by introducing polar functional groups (such as carboxyl, hydroxyl, or amino groups) into the polyurethane chains. This parameter change in molecular polarity enhances the interaction between polymer chains, improving both the elastic recovery and stretchability while maintaining waterproof integrity through controlled crosslinking.
2Ease of manufacture
If petrochemical raw materials are used, then waterproof textiles can be produced, but greenhouse gas emissions from petrochemical production increase
Solution Approach 1:
The patent extracts and utilizes natural rubber (polyisoprene) from renewable biomass sources, specifically replacing a portion of petrochemical raw materials with naturally occurring polymers. This extraction of natural polymers from renewable sources reduces dependence on petrochemicals and consequently lowers greenhouse gas emissions associated with petroleum extraction and processing.
Solution Approach 2:
The patent changes the source parameter of raw materials from non-renewable petrochemicals to renewable biomass-derived polyisoprene. This fundamental parameter change in material origin reduces the carbon footprint of production while maintaining the desired textile performance characteristics.
3Adaptability or versatility
If natural rubber tree materials are used, then biomass substitution is achieved, but moisture permeability is lost and allergic reactions may occur due to protein presence
Solution Approach 1:
The patent extracts and removes proteins and other allergenic impurities from the natural rubber through purification processes, obtaining high-purity polyisoprene. This extraction of harmful components eliminates the risk of allergic reactions while retaining the beneficial elastic properties of natural rubber.
Solution Approach 2:
The patent creates a porous or semi-permeable structure in the composite membrane through controlled crosslinking and foam formation, enabling moisture vapor transmission. This porous structure allows water molecules to pass through while maintaining the barrier properties against liquid water, thus achieving moisture permeability in the biomass-based material.
4Ease of operation
If a mixture of polyisoprene and polyurethane with polar functional groups is crosslinked, then excellent stretchability and moisture permeability are achieved, but the manufacturing process complexity increases
Solution Approach 1:
The patent merges the crosslinking process with the foam formation and membrane formation steps into a single integrated operation. By combining multiple functions (crosslinking agent addition, vulcanization, and membrane formation) into one continuous process, the manufacturing complexity is reduced despite the advanced material composition.
Solution Approach 2:
The patent uses a crosslinking agent as an intermediary substance that facilitates the crosslinking reaction between polyisoprene and polyurethane chains. This intermediary enables the formation of the desired composite structure with enhanced stretchability and moisture permeability while simplifying the control of the manufacturing process through a well-defined chemical reaction mechanism.
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 composite membrane achieves excellent moisture permeability and stretchability, reducing the need for petrochemical materials and minimizing environmental impact.
Implementation Method 1
subjecting a mixture to a crosslinking treatment. The mixture contains a polyisoprene, a polyurethane with a polar functional group, a crosslinking agent, and a vulcanizing agent
Implementation Method 2
subjecting the release substrate to a drying treatment to allow the preformed film to undergo a crosslinking reaction
Data Source
AI summary
A moisture-permeable composite membrane is manufactured by the step of subjecting a mixture to a crosslinking treatment. The mixture contains a polyisoprene, a polyurethane with a polar functional group, a crosslinking agent, and a vulcanizing agent. In the mixture, a weight ratio of the polyurethane with the polar functional group to the polyisoprene ranges from 1:0.55 to 1:6.60. A method for manufacturing the moisture-permeable composite membrane is also provided.