Pumpable Expandable Sealant Composition for Sag-Resistant Vehicle Cavities
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Solution Overview
Problem
Existing pumpable sealants for vehicle cavities face challenges such as sagging, poor adhesion, and rigidity issues, which are not adequately addressed by current materials like epoxy resin and heat foamable pastes, leading to sealing failures and increased complexity in application and logistics.
Innovation Solution
A composition comprising styrene butadiene rubber (SBR), PVC homopolymer or copolymer, amide wax thixotropic agent, blowing agent, vulcanizing agent, and optional additives like functionalized liquid rubber and fillers, which provides sag resistance, adhesion, and expansion properties when heated, allowing for automated application and reduced material usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If epoxy resin and filler are used to address sag problems, then sag resistance is improved, but the material becomes rigid and inflexible after cure, causing holes between material and top panel
Solution Approach 1:
The patent changes the chemical composition parameters by using liquid rubber as the base material instead of epoxy resin, and by controlling filler content to 1-20 wt%. This parameter change allows the material to maintain flexibility while achieving sag resistance through the liquid rubber's inherent properties and controlled expansion rather than through rigid filler reinforcement.
Solution Approach 2:
The patent creates a composite material system combining liquid rubber with specific fillers (1-20 wt%) and curing agents. This composite approach allows the material to achieve both sag resistance and flexibility by balancing the rigidifying effect of fillers with the flexible nature of liquid rubber, preventing the material from becoming too rigid after cure.
2Stability of the object's composition
If paste type heat foamable materials with large amounts of inorganic filler are used, then sag resistance is improved, but the material becomes rigid and inflexible after cure
Solution Approach 1:
The patent limits inorganic filler content to 1-20 wt% while using liquid rubber as the base material. This parameter change ensures the material remains sufficiently flexible after curing by preventing excessive rigidification from fillers, while still achieving sag resistance through the liquid rubber's expansion and adhesion properties.
Solution Approach 2:
The patent uses liquid rubber which can be applied in a pumpable, processable state and then cures in place to form the final flexible seal. This approach allows the material to be applied in a convenient liquid form and then becomes the permanent flexible seal, avoiding the need for rigid pre-formed components.
3Stability of the object's composition
If quinone-based vulcanizing agent is used as self-skinning agent, then sag prevention is improved, but wetting between bead surface and metal panel is prevented
Solution Approach 1:
The patent uses liquid rubber as an intermediary material that provides both sag prevention through its expansion and adhesion through its chemical bonding to metal panels. The liquid rubber acts as a mediator between the applied bead and the metal surface, ensuring both sag resistance and strong adhesion without requiring self-skinning agents that would prevent wetting.
Solution Approach 2:
The patent changes the curing mechanism from self-skinning (quinone-based) to conventional vulcanization with controlled curing agents. This parameter change allows the material to maintain wetting and adhesion to metal panels while still achieving sag prevention through the liquid rubber's expansion and bonding properties.
4Extent of automation
If pumpable expandable sealant is applied to replace tapes and 3D parts, then automation and logistics are improved, but sagging occurs when bead thickness is greater than 10 to 20 mm
Solution Approach 1:
The patent optimizes the sealant formulation by controlling filler content (1-20 wt%) and using liquid rubber as the base material. This parameter change allows the material to maintain pumpability for automated application while achieving sufficient sag resistance even at bead thicknesses greater than 10-20 mm through its expansion and adhesion properties.
Solution Approach 2:
The patent creates a composite sealant material combining liquid rubber with controlled amounts of filler (1-20 wt%). This composite formulation provides both the pumpability needed for automated application and the sag resistance required for thick beads, by balancing the rheological properties of the liquid rubber with the structural support from the controlled filler content.
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 composition achieves improved sag resistance and adhesion, enabling efficient sealing of vehicle cavities with reduced material complexity and logistics, and allows for automated application, while maintaining flexibility and adhesion after curing.
Implementation Method 1
pumpable thermally expandable sealant composition that expand when heated and adhere to cavity surfaces thereby sealing the cavity
Implementation Method 2
a blowing agent
Implementation Method 3
a vulcanizing agent
Implementation Method 4
a wax thixotropic agent
Implementation Method 5
adhere to cavity surfaces thereby sealing the cavity
Data Source
AI summary
Disclosed are pumpable expandable compositions useful in sealing cavities in vehicles, and methods of applying the compositions which significantly improve vertical and inverted sag resistance without detracting from performance; compositions of the invention and methods of applying them provide greater versatility in sealing larger gaps and cavities due to improved expansion height.