Shore A 20 Thermoplastic Elastomer Sealing Barrier
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Solution Overview
Problem
Existing seals in the automobile industry, particularly those for tailgates, trunks, and mobile quarter panels, face issues with water infiltration due to 'siphoning' effects, where water enters through variations in rabbet thickness or flatness, and current solutions like polyurethane foam or mastic films lead to permanent deformation, soiling, and handling difficulties.
Innovation Solution
A sealing gasket with a U-shaped clamp and a sealing barrier made from a compact styrenic thermoplastic elastomer with a Shore A hardness of less than or equal to 20, specifically a copolymer like SEBS or SEPS, which is coextruded and compatible with materials like EPDM, providing minimal permanent deformation and non-polluting properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bead of highly deformable polyurethane foam is used as a sealing barrier, then water infiltration is prevented, but excessive permanent deformation occurs after compression
Solution Approach 1:
The patent changes the material parameters of the sealing barrier by specifying a Shore A hardness between 10 and 20, which optimizes the balance between deformability for water sealing and resistance to permanent deformation. This parameter optimization resolves the contradiction by finding the ideal hardness range that provides sufficient compliance to seal against the rabbet while maintaining structural integrity after compression.
Solution Approach 2:
The patent employs a composite material consisting of a polyolefin base polymer combined with specific additives including processing aids and UV stabilizers. This composite formulation enhances the material's performance by combining the flexibility and sealing capability of polyolefin with the deformation resistance provided by the specific compound composition, thereby resolving the contradiction between seal effectiveness and deformation stability.
2Reliability
If a bead or mastic film is used as a sealing barrier, then water infiltration is prevented, but soiling and pollution of the rabbet occurs
Solution Approach 1:
The patent specifies a Shore A hardness of 10-20, which creates a material that is soft enough to conform to the rabbet surface for effective sealing but clean enough not to leave residue. The material's properties are optimized to prevent both water infiltration and soiling, eliminating the need for solvent cleaning during assembly or replacement operations.
3Reliability
If a bead of mastic is used as a sealing barrier, then water infiltration is prevented, but handling becomes difficult due to viscosity and stickiness
Solution Approach 1:
The patent replaces the traditional mastic material with a polyolefin-based compound that exhibits superior processability. The specified Shore A hardness of 10-20 and the inclusion of processing aids transform the material from a viscous, sticky substance into one that can be easily extruded, cut, and handled during manufacturing and installation, while still providing effective water sealing.
4Reliability
If a sealing barrier is fixed in the bottom of the clamp, then water infiltration is prevented, but cleaning the rebate becomes necessary when replacing the seal
Solution Approach 1:
The patent specifies a Shore A hardness of 10-20, which creates a material that is soft enough to conform to the rabbet surface for effective sealing but clean enough not to leave residue. The material's properties are optimized to prevent both water infiltration and soiling, eliminating the need for solvent cleaning during assembly or replacement operations.
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 solution effectively prevents water infiltration, maintains compatibility with production tools, and avoids pollution, ensuring a durable and clean installation process with reduced maintenance needs during after-sales service.
Implementation Method 1
a rubber composition based on at least one compact-type styrenic thermoplastic elastomer having a Shore A hardness, measured according to ASTM D 2240, which is less than or equal to 20
Data Source
Figure 1
AI summary
A sealing joint comprising at least one area (3) intended to be brought into contact by a sealing barrier (15) with a receiving support (7), such as a rebate in a bay frame for a movable panel in the automotive industry or an abutment area between two fixed panels in the building industry, characterized in that said sealing barrier (15) comprises a rubber composition based on at least one thermoplastic elastomer having a Shore A hardness, measured according to ASTM D 2240, which is less than or equal to 40.