Low-Emission Spray Polyurethane Carrier Layer
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Solution Overview
Problem
Current spray polyurethane systems used for producing carrier layers in molded parts, such as those in automobile construction, face challenges in achieving low emissions and improved mechanical properties like tensile strength, elongation, and tear resistance while maintaining the advantages of polyisocyanate polyaddition products.
Innovation Solution
A spray polyurethane system comprising a polyol component with specific isocyanate-reactive compounds, reactive chain extenders, and a metal catalyst, without amine catalysts, utilizing polyether polyols with targeted molecular weights and functionalities, and optionally including additives for thixotropy and water absorption, to enhance the reaction and properties of the polyurethane carrier layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If conventional spray polyurethane systems with amine catalysts and standard polyol compositions are used, then the carrier layer achieves adequate mechanical properties and fast processing, but emissions of volatile components remain high
Solution Approach 1:
The patent changes the chemical composition parameters of the polyol component, specifically using polyether polyols with number-average molecular weights of 1500-3500 g/mol and functionalities of 2.0 or less, combined with polyether polyols having number-average molecular weights of 3000-6000 g/mol and functionalities of 2.2 or greater. This parameter optimization enables low emissions while maintaining mechanical properties without requiring amine catalysts
Solution Approach 2:
The patent extracts and eliminates amine catalysts from the spray polyurethane system, replacing them with metal catalysts. This removal of the harmful amine component directly reduces volatile emissions while the specific polyol composition ensures adequate reaction kinetics and mechanical property development
2Strength
If the carrier layer is optimized for low emissions and improved mechanical properties, then tensile strength and tear resistance increase, but processing time may be extended
Solution Approach 1:
The patent optimizes the molecular weight distribution and functionality of polyether polyols to achieve enhanced mechanical properties. The specific combination of lower molecular weight polyols (1500-3500 g/mol) with functionality ≤2.0 and higher molecular weight polyols (3000-6000 g/mol) with functionality ≥2.2 creates an balanced polymer network that develops strength while maintaining acceptable processing timelines
3Object-generated harmful factors
If polyether polyols with specific molecular weights and functionalities are used, then mechanical properties and emission reduction are achieved, but formulation complexity increases
Solution Approach 1:
The patent establishes specific parameter ranges for polyether polyols (molecular weight 1500-6000 g/mol, functionality 2.0-2.2) that balance performance requirements with formulation manageability. These defined parameters provide a systematic approach to achieving low emissions and good mechanical properties without excessive formulation complexity
Solution Approach 2:
The patent employs a composite polyol system combining different types of polyether polyols with complementary properties. This composite approach allows the formulation to achieve multiple objectives (low emissions, good mechanical properties, adequate processing) through the synergistic interaction of components with specific molecular weight and functionality characteristics
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 system achieves improved mechanical properties, including increased tensile strength, elongation, and tear resistance, while reducing emissions of volatile components, and extends the processing time without compromising demolding efficiency, resulting in a carrier layer with enhanced performance and reduced VOC emissions.
Implementation Method 1
Polyisocyanate polyaddition products, usually polyurethanes and/or polyisocyanurates, obtainable by reacting isocyanates with compounds reactive towards isocyanates
Implementation Method 2
the spray polyurethane system does not contain an amine catalyst and where the isocyanate-reactive compound a1) at least one polyether polyol with a number-average molecular weight of 1500 to 3500 g/mol and a functionality of 2.0 or less and at least one polyether polyol with a number-average molecular weight of 3000 to 6000 g/mol and a functionality of 2.2 or greater
Data Source
AI summary
The present invention relates to a spray polyurethane system which contains a polyol component (A) and an isocyanate component (B), wherein the polyol component (A) contains a1) at least one compound reactive with isocyanate, a2) at least one reactive chain extender with at least two groups reactive with isocyanate, wherein at least one group reactive with isocyanate is a free, primary NH2 group, as well as a3) at least one metal catalyst and a4) optionally other additives, wherein the spray polyurethane system contains no amine catalyst. The present invention also relates to a method for producing a polyurethane backing layer for molded parts and the use of this backing layer for producing automobile parts. The backing layers according to the invention show good mechanical characteristics and low emissions, and have a short demolding time compared to the open time.