Rubber Adhesive Composition for Low-Temperature Curing and Overbake Resistance
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Solution Overview
Problem
Existing adhesives and sealants used in automotive manufacturing face challenges with high cure temperatures, extended cure times, poor storage stability, and sensitivity to overbaking, which are exacerbated by the non-uniform body temperatures in electric vehicles, leading to underbake or overbake issues.
Innovation Solution
A thermally curable rubber-based composition that cures at reduced temperatures (130° C.-140° C.) with a cure time of 10-20 minutes, using a curing system comprising quinone dioxime, peroxide, and a multifunctional coagent, while minimizing traditional accelerators, and includes processing oils and fillers to promote pumpability and sag resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If traditional curing systems are used, then good adhesion and strength are achieved, but cure temperature must be 160-200°C which conflicts with low temperature e-coat curing requirements
Solution Approach 1:
The patent changes the chemical parameters of the curing system by replacing traditional sulfur-based accelerators with quinone dioxime and peroxide combinations, enabling the composition to cure at lower temperatures (130-140°C) while maintaining adhesion performance. This parameter change in the curing chemistry allows compatibility with low-temperature e-coat processes.
Solution Approach 2:
The patent uses a composite curing system combining multiple components: quinone dioxime, peroxide, and multifunctional coagents. This composite approach provides synergistic effects that enable low-temperature curing while maintaining reliable adhesion to metal substrates, resolving the contradiction between low temperature requirement and adhesion performance.
2Temperature
If extended cure time is used to achieve low temperature curing, then curing can proceed at lower temperatures, but cure time increases to 150 minutes which conflicts with line assembly process time constraints
Solution Approach 1:
The patent changes the kinetic parameters of the curing reaction by using highly active quinone dioxime and peroxide accelerators, which dramatically increase the curing rate. This allows the composition to cure at low temperatures (130-140°C) but complete curing within 10-20 minutes, resolving the time conflict.
Solution Approach 2:
The patent replaces the time-based curing mechanism with a chemically accelerated mechanism. Instead of relying on extended thermal exposure, the composition uses chemical accelerators to initiate rapid curing, substituting time for chemical reactivity and enabling both low temperature and short duration curing.
3Temperature
If accelerated curing systems are used to achieve curing below 160°C, then low temperature curing is achieved, but storage stability deteriorates limiting shelf-life
Solution Approach 1:
The patent extracts and removes problematic sulfur-based accelerators from the curing system that cause storage instability. By taking out these harmful components and replacing them with quinone dioxime and peroxide systems, the composition achieves low-temperature curing while improving storage stability and shelf-life.
Solution Approach 2:
The patent uses a single-component system with carefully selected accelerators that are stable during storage but become active only under heat. The accelerators are designed to remain dormant during storage (maintaining stability) but activate rapidly during curing, effectively being 'inactive during storage, active during use'.
4Strength
If conventional rubber-based compositions are used, then good adhesion is achieved, but reversion resistance to high temperature overbaking is insufficient
Solution Approach 1:
The patent changes the thermal stability parameters of the curing system by using quinone dioxime and peroxide combinations that form stable crosslinks resistant to reversion at high temperatures. This parameter change in the curing chemistry provides both good adhesion and resistance to overbaking damage.
Solution Approach 2:
The patent incorporates reversion-resistant curing chemistry that protects against high-temperature damage before it occurs. The quinone dioxime and peroxide system creates thermally stable crosslinks that cushion against the harmful effects of overbaking, preventing strength degradation even when exposed to temperatures above 200°C.
5Reliability
If additional reinforcement mass is added to protect battery systems in EVs, then battery protection is improved, but thermal energy requirements increase creating heat sink effects and non-uniform curing
Solution Approach 1:
The patent changes the curing temperature parameter to a lower range (130-140°C) with extended hold time, which allows sufficient heat penetration into thick reinforced sections without creating excessive temperature gradients. This parameter adjustment enables uniform curing across varying thicknesses while maintaining battery protection reinforcement.
Solution Approach 2:
The patent implements a dynamic curing profile with extended hold time at lower temperature, allowing the heating process to adapt to different section thicknesses. The extended holding period enables thermal equilibrium to be achieved throughout the bonded assembly, ensuring uniform curing even in sections with additional reinforcement mass.
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 reversion resistance to high cure temperatures (190° C.-230° C.), maintaining strength and adhesion to metal surfaces, particularly aluminum, with uniform curing characteristics across varying vehicle body temperatures.
Implementation Method 1
a curing system comprising two or more of: quinone dioxime; peroxide, and a multifunctional coagent
Implementation Method 2
A thermally curable rubber-based composition curable at reduced temperatures of about 130° C.-140° C.
Data Source
AI summary
The invention relates to a rubber-based composition that can be thermally cured at reduced temperature while retaining performance over a broad cure temperature window comprising at least one solid rubber, at least one diene-based polymer or copolymer containing an olefinic double bond and/or an aromatically substituted olefin, suitable for undergoing curing with a curing system present as quinone dioxime, peroxides and optional multifunctional acrylates, preferably in the absence of elemental sulfur. The cured composition exhibits improved reversion resistance and adhesion strength on aluminum.