Rubber Composition for High Elasticity and Adhesion
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Solution Overview
Problem
Existing rubber-based adhesives and sealants for automobile construction lack high elasticity combined with high tensile shear strength, making them unsuitable for simultaneous use as seam adhesives and sealants, and they require warm application methods, limiting their application methods to injection or extrusion.
Innovation Solution
A hot-curing reactive composition based on natural and/or synthetic polymers and vulcanizing agents containing olefinic double bonds, with specific ratios of liquid cis-1,4-polyisoprene, polybutadiene, and vulcanization systems, allowing for pre-curing at 120-150 °C and easy application by injection, spraying, or extrusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If rubber-based adhesives with high tensile shear strength are used, then adhesion performance is improved, but elasticity is reduced (elongation at break does not exceed 15%)
Solution Approach 1:
The patent changes the chemical composition parameters by incorporating specific functional groups (hydroxyl, carboxyl, amino, isocyanate, epoxy, anhydride) into the rubber polymer structure. This enables the adhesive to achieve both high tensile shear strength (>4 MPa) and high elasticity (>130% elongation at break) simultaneously, resolving the contradiction between strength and elasticity that limited previous rubber-based adhesives to maximum 15% elongation.
2Strength
If high-viscosity rubber compositions are used to achieve high strength, then adhesion is improved, but applicability is reduced (cannot be sprayed, must be extruded at higher temperature)
Solution Approach 1:
The patent modifies the rheological parameters of the rubber composition by adjusting viscosity to a range of 10-500 Pa·s at 25°C. This parameter change enables the adhesive to be applied by conventional spray methods while maintaining high adhesion strength, eliminating the requirement for high-temperature extrusion and expanding application method options beyond injection and extrusion.
3Stability of the object's composition
If elastomers with low glass transition temperature are used to improve elasticity, then elongation is improved, but tensile shear strength is reduced
Solution Approach 1:
The patent creates a composite material system combining elastomers with low glass transition temperature (below -50°C) with specific functional groups. This composite approach achieves both high elasticity (>130% elongation at break) and high tensile shear strength (>4 MPa), resolving the inverse relationship between elasticity and strength that previously forced a trade-off between these properties.
4Strength
If conventional rubber adhesives are used for seam bonding, then adhesion is achieved, but separate sealing requires additional products and logistics
Solution Approach 1:
The patent develops a universal adhesive composition that simultaneously provides both bonding and sealing functions. The composition achieves adhesion strength >4 MPa and elasticity >130%, enabling it to serve as both seam adhesive and sealant in automobile body construction. This multi-functionality eliminates the need for separate sealing products and reduces logistics complexity, directly addressing the limitation of conventional rubber adhesives that required additional sealing materials.
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 high elasticity (>130%) and tensile shear strength (>4 MPa), enabling its use as both a seam adhesive and sealant with excellent aging resistance, reducing logistics and costs, and allowing for pre-hardening at low temperatures.
Implementation Method 1
a hot-curing reactive composition based on natural and/or synthetic polymers and vulcanizing agents containing olefinic double bonds
Implementation Method 2
the composition contains at least one liquid cis-1,4-polyisoprene, a vulcanization system, and at least one polybutadiene that is liquid at 22 °C
Implementation Method 3
allowing for pre-curing at 120-150 °C and easy application by injection, spraying, or extrusion
Data Source
Figure 1
AI summary
The invention relates to a heat-curing, reactive composition based on natural and/or synthetic, olefinic, double-bond-containing polymers and vulcanizing agents which contain a) at least one liquid cis-1,4-polyisoprene with a weight-average molecular weight between 20000 and 70000, b) a vulcanization system, c) at least one polybutadiene which is liquid at 22 °C, wherein: a) the liquid cis-1,4-polyisoprene constitutes 9 to 15 wt.% of the total composition; b) the vulcanization system is selected from the group consisting of b1) sulfur and one or more vulcanization accelerator(s) (n), b2) peroxidic or disulfidic vulcanization systems, and b3) quinines, quinine dioximes, or dinitrosobenzene; and c) the polybutadiene which is liquid at 22 °C constitutes 16 to 29 wt.%. of the total composition.