Coextruded Rubber Interface Bond Strength via Preform Embossing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The bond strength between coextruded rubber mixtures is a point of separation or fracture, limiting the mechanical properties of rubber products, as the crosslinking structures in the boundary layer differ from those in the core, and existing co-vulcanization processes do not adequately enhance adhesion.
Innovation Solution
Increasing the interface size between vulcanizable rubber compositions by designing a preform with a structural element having complementary macroscopic structures on both sides, which embosses into the rubber mixtures, creating a macroscopically structured interface that enhances crosslinking and adhesion during coextrusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional coextrusion process is used, then rubber compounds can be coextruded to form final product, but bond strength at interface is insufficient and separation occurs
Solution Approach 1:
The patent applies curvature by using a rounded nose section at the end of the preform instead of a flat or sharp edge. This curved geometry increases the contact area between the two rubber compounds during coextrusion, creating a larger interface for bonding. The rounded shape allows for better distribution of contact pressure and enhanced interfacial adhesion, directly addressing the bond strength issue.
Solution Approach 2:
The patent implements preliminary action by pre-forming the rubber compounds into a preform with a specific nose section geometry before the actual coextrusion process. This preforming step prepares the rubber compounds in advance with an optimized shape that will maximize interface contact during subsequent vulcanization and coextrusion, ensuring better bond strength from the outset.
2Strength
If interface size is increased, then bond strength is improved, but preform design complexity increases
Solution Approach 1:
The patent applies local quality by modifying only the nose section of the preform where the interface contact occurs, rather than redesigning the entire preform structure. The rounded nose section is a localized geometric feature that specifically addresses the bonding issue at the interface while leaving the rest of the preform design relatively simple and straightforward to manufacture.
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 leads to a synergistically increased bond strength in the vulcanized rubber product due to increased crosslinking and macroscopic interlocking, resulting in improved mechanical properties and reduced potential for fracture.
Implementation Method 1
the structural element is configured to imprint complementary macroscopic structures into the vulcanizable rubber compounds extruded through the forming openings
Implementation Method 2
Within this boundary layer, the structures cross-linked during vulcanization differ from those formed in the core of the respective rubber compounds
Implementation Method 3
the co-vulcanization step of the two vulcanizable rubber compounds plays a crucial role in determining the bond strength
Implementation Method 4
the rubber compounds are fed through a pre-die into a final die, where they are then fused under high pressure to form the final rubber product
Data Source
Figure 1~2
Figure 3~4
Figure 5~7
AI summary
The invention relates to a method for co-extruding a vulcanizable rubber product with an extruder, comprising the process steps of: a) producing or providing a first vulcanizable rubber compound and a second vulcanizable rubber compound, b) pre-forming the first vulcanizable rubber compound through a first die opening of a pre-mold and pre-forming the second vulcanizable rubber compound through a second die opening of the pre-mold, c) contacting the pre-formed rubber compounds in a downstream end die of the extruder to form an interface between the rubber compounds, and d) extruding the vulcanizable rubber product comprising the first vulcanizable rubber compound and the second vulcanizable rubber compound.wherein the first forming opening and the second forming opening in the pre-template are separated from each other by a structural element, wherein the structural element has a complementary macroscopic structure on both sides, and wherein the structural element is configured to imprint complementary macroscopic structures into the vulcanizable rubber compounds extruded through the forming openings, such that these have a macroscopically structured interface with each other in cross-section through the vulcanizable rubber product.