Microcellular Polyurethane Foam Elastic Recovery
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Solution Overview
Problem
Polyurethanes and polyurethane-ureas struggle to combine high elastic recovery, resistance to abrasion, chemical resistance, and mechanical properties suitable for applications under variable and temporary loads or vibrations, especially in harsh temperature and humidity conditions, such as in railway shock absorbers and car bumpers.
Innovation Solution
Development of microcellular polyurethane and polyurethane-urea foams with specific reactant compositions and reaction conditions, including a prepolymer with unreacted NCO groups and a compound containing macrodiols and macropolyols, formed in the presence of water or a blowing agent and a catalyst, to achieve a unique combination of properties like low compression set, high abrasion resistance, and chemical resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a relatively rigid structure is used to achieve good mechanical properties and resistance to loads and vibrations, then mechanical strength is improved, but elastic recovery of form (compression set) deteriorates
Solution Approach 1:
The patent employs composite materials by combining polyurethane and polyurethane-urea in specific ratios (30-70 wt% polyurethane-urea and 70-30 wt% polyurethane) to create a material that exhibits both rigidity for load resistance and elasticity for form recovery, resolving the contradiction between mechanical strength and elastic recovery
Solution Approach 2:
The patent changes the chemical composition parameters by controlling the NCO index (1.05-1.30) and the specific ratio of polyurethane to polyurethane-urea, which allows optimization of both mechanical strength and elastic recovery properties simultaneously through precise parameter control
2Reliability
If softer polymers are used to achieve high elastic recovery of form, then elastic recovery is improved, but mechanical strength and resistance to loads deteriorates
Solution Approach 1:
The patent uses composite materials combining softer polyurethane components with polyurethane-urea, where the softer polyurethane provides elastic recovery while the polyurethane-urea contributes mechanical strength, achieving both properties through material composition
3Reliability
If the material structure is modified to improve resistance to abrasion and chemical resistance, then durability is improved, but the combination of all desired properties becomes more difficult to achieve
Solution Approach 1:
The patent uses composite polyurethane-polyurethane-urea materials that inherently provide improved resistance to abrasion and chemicals while maintaining mechanical properties, achieving multiple desired properties simultaneously through the composite structure rather than through complex modifications
Solution Approach 2:
The patent modifies the chemical composition parameters, specifically the NCO index (1.05-1.30) and component ratios, to achieve a balanced formulation that provides abrasion resistance, chemical resistance, mechanical strength, and elastic recovery without excessive complexity
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 foams exhibit improved elastic recovery, mechanical strength, and resistance to abrasion and chemicals, making them suitable for high-variable load applications like railway pads and car bumpers, with specific properties meeting the requirements for durability and performance in challenging conditions.
Implementation Method 1
said reaction product of (A)+(B) being obtained in the presence of water and/or a physical and/or chemical blowing agent, and a catalyst for formation of the urethane and/or ureic groups
Data Source
AI summary
A microcellular polyurethane or polyurethane-urea foam elastomer includes the reaction product of (A) with (B) and/or water, a blowing agent, a catalyst forming urethane and/or ureic groups wherein:(A) is a prepolymer having a —NCO free group content included between 2%-25% (% w/w), which includes the reaction product of(a1) one or more aliphatic, cycloaliphatic and/or aromatic diisocyanates excluding 3,3′-dimethyl-4,4′-diphenylene diisocyanate, or one or more polyisocyanates or mixture of diisocyanates and polyisocyanates;with(a2a) one or more polyester macrodiols, a number of —OH groups per molecule equal to about 2;(B) is a compound selected from(b1) a diol or polyol;(b2) a primary or secondary aliphatic, cycloaliphatic amine or aliphatic, cycloaliphatic aromatic disecondary diamine or a blocked amine;(b3) one or more polyester macrodiols having a number of —OH group per molecule equal to about 2;(b4) a mixture formed of two or more compounds (b1), (b2) and (b3).