Heterogeneous Foam via Concurrent Mold Foaming
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Solution Overview
Problem
Current methods for producing molded polyolefin foams face limitations in design flexibility due to material stretching issues and environmental hazards associated with polyurethane foam-in-place soft IP, while traditional foam products have homogeneous compositions and uniform properties, lacking the ability to achieve heterogeneous properties efficiently.
Innovation Solution
A method involving the concurrent foaming of two or more foamable materials with physical, chemical, or quantitative differences within the same mold space to produce a heterogeneous foam product with varying characteristics such as color, density, and haptics, without pre-foaming or post-processing steps, using physically crosslinked foamable particles to control density and properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If PO vacuum-formed soft IP is used to achieve low density and lightweight properties, then weight is reduced, but design flexibility is limited due to material stretching in deep cavities
Solution Approach 1:
The mold cavity is divided into multiple regions, each filled with different foamable materials having distinct expansion characteristics. This segmentation allows each material to expand independently to its optimal density without excessive stretching, enabling complex designs while maintaining low overall weight.
Solution Approach 2:
Different regions of the foam product are assigned different material compositions and expansion rates tailored to local design requirements. Areas requiring high density receive materials with lower expansion rates, while areas needing low density receive materials with higher expansion rates, achieving heterogeneous properties throughout the single-part structure.
2Adaptability or versatility
If PU foam-in-place soft IP is used to achieve design freedom and even haptics, then adaptability is improved, but density increases and weight increases
Solution Approach 1:
The expansion rate parameter of the foamable materials is precisely controlled through selection of materials with different compositions and additives. By adjusting this parameter, the foam expands to fill cavities evenly while achieving target density levels, enabling design freedom without excessive weight gain.
Solution Approach 2:
Multiple foamable materials with different base polymers and expansion characteristics are combined in a single mold. This composite approach allows the formulation of low-density foams that expand evenly throughout complex cavities, achieving both design freedom and lightweight properties simultaneously.
3Reliability
If chemical crosslinking is used to produce foamable particles, then foam stability is improved, but undesirable odors are generated and crosslinking level becomes difficult to control
Solution Approach 1:
The crosslinking function is extracted from the foamable particle formulation and placed into the mold as a separate physical crosslinking mechanism. This eliminates the need for chemical crosslinking agents within the foam particles, removing the source of odors while maintaining foam stability through physical crosslinking in the mold.
Solution Approach 2:
A physical crosslinking mechanism acts as an intermediary between the foamable particles and the final foam structure. This physical mechanism provides the necessary crosslinking for stability without introducing chemical agents that would generate odors, serving as a clean alternative to chemical crosslinking.
4Ease of manufacture
If traditional homogeneous foam composition is used to ensure uniform properties, then manufacturing simplicity is maintained, but heterogeneous properties required for different applications cannot be achieved
Solution Approach 1:
The manufacturing process is segmented into multiple stages: preparation of different foamable materials, their selective placement in mold regions, and concurrent foaming. This segmentation enables heterogeneous properties to be achieved through a systematic process rather than complex multi-step operations, maintaining ease of manufacture while enabling property variation.
Solution Approach 2:
Multiple foamable materials with different properties are merged into a single mold and foamed concurrently. This merging approach produces a single heterogeneous foam product with multiple regions of different properties, eliminating the need for separate manufacturing steps for each material while achieving the desired property variation.
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
This approach allows for the creation of lightweight, low-toxicity, odorless foams with complex designs and tailored properties, suitable for broader applications like automotive instrument panels, while reducing VOC emissions and production costs by using higher-cost materials only where necessary.
Implementation Method 1
the foamable particles are in a physically crosslinked state prior to foaming
Implementation Method 2
Both the first and second foamable materials are then concurrently foamed inside of the mold space
Data Source
AI summary
A process comprises placing a first foamable material inside of a first region of a mold space, and a second foamable material inside of a second region of the mold space, the first foamable material and the second foamable material comprising a physical, chemical or quantitative difference or any combination thereof. Both the first and the second foamable materials are concurrently foamed inside of the mold space to produce a heterogeneous foam comprising a first portion that differs from the second portion.