Polyurethane Foamed Parts With Polyester Polyols for Improved Flow
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Solution Overview
Problem
Existing methods for manufacturing automotive interior parts with semi-flexible polyurethane foam face challenges in achieving good flow properties, leading to higher material costs and VOC emissions, especially in complex mold geometries with elongated thin foam layers, which can cause defects and environmental issues.
Innovation Solution
A process involving a polyurethane foam formulation with specific isocyanate-reactive materials, including polyether and polyester polyols, crosslinkers, water, and a urethane catalyst, is used to form a skinned composite with excellent flow and low VOCs, adhering to a polymer or natural leather skin layer in a mold with controlled unfilled regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If foam formulation is injected through one or two ports into elongated thin mold cavities, then manufacturing complexity is reduced, but flow properties deteriorate causing voids and defects
Solution Approach 1:
The invention divides the mold cavity into multiple injection zones by providing three or more injection ports distributed along the elongated cavity. This segmentation allows the foam formulation to be injected from multiple points simultaneously, improving flow distribution and eliminating voids while maintaining the simplicity of the overall molding process.
Solution Approach 2:
The invention transitions from single-point or dual-point injection to multi-point injection along the length of the elongated mold cavity. By adding the dimension of distributed injection points along the cavity length, the formulation achieves better flow coverage without increasing vertical or lateral complexity of the mold structure.
2Reliability
If more foam formulation is used to fill complex mold cavities, then flow properties improve, but material costs increase
Solution Approach 1:
By segmenting the injection process into multiple ports, the foam formulation is distributed more efficiently throughout the mold cavity. This reduces the total volume of foam needed compared to single-port injection, as the formulation flows from multiple points simultaneously, eliminating the need to over-fill to compensate for poor flow distribution.
Solution Approach 2:
The invention changes the injection parameters by distributing injection ports along the cavity length, which optimizes the flow path and reduces the total formulation quantity required. The multi-port configuration allows better utilization of the injected material, reducing waste and material costs.
3Reliability
If amine compounds are used in foam formulation, then curing performance improves, but VOC emissions increase causing embrittlement and discoloration
Solution Approach 1:
The invention replaces harmful amine compounds with alternative catalysts that do not generate VOC emissions. The alternative catalyst system achieves equivalent or superior curing performance without the harmful side effects of embrittlement and discoloration, effectively converting a harmful formulation approach into a beneficial one.
Solution Approach 2:
The invention changes the chemical composition parameters of the foam formulation by substituting amine-based catalysts with alternative catalyst systems. This parameter change eliminates VOC emissions while maintaining the necessary curing performance, addressing both the functional requirement and the environmental concern.
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 process achieves superior flow properties, reducing material costs and VOC emissions, while maintaining mechanical integrity and reducing defects in the foam parts, particularly in elongated mold cavities.
Implementation Method 1
A liquid mixture of foam precursors is injected (in a closed pour process) or poured (in an open pour process) into the mold, where the mixture reacts and expands against the skin to form the part
Implementation Method 2
the foam formulation must be able to flow throughout the entire mold cavity and fill it without leaving voids or other defects
Implementation Method 3
the foam formulation must be able to flow throughout the entire mold cavity and fill it without leaving voids or other defects. This is complicated due to the small thickness of the foam cavity and the rather long distances from the injection ports to remote sections of the mold
Implementation Method 4
the polyurethane foam formulation expands, contacts an exposed surface of the polymer or natural leather skin layer and forms a polyurethane foam that fills the unfilled region of the mold cavity and adheres to the polymer or natural leather skin layer and substrate if present
Data Source
AI summary
Composites having a polymer or natural leather skin layer and a polyurethane foam layer are made in a molding process. The polyurethane foam layer is made from a foam formulation that includes certain polyester polyols. The presence of the polyester polyol improves flow characteristics of the foam formulation. The foam so produced has unexpectedly low quantities of VOCs.