Thermally Expandable Urea Derivative Compositions for Automotive Sealing
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Solution Overview
Problem
Modern automotive components with cavities face challenges in sealing to prevent moisture and contaminant ingress, noise transmission, and require lightweight, rigid structures, but existing exothermic blowing agents are hazardous, explosive, and produce prohibited by-products, leading to high water absorption and inconsistent foam structures.
Innovation Solution
Thermally expandable compositions comprising peroxidically cross-linking polymers, peroxides, and endothermic chemical blowing agents, specifically carboxylic acids and urea derivatives, which are safer, produce fewer VOCs, and offer lower water absorption and consistent foam structures across a wider temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If exothermic blowing agents are used, then expansion and foaming occur, but respiratory sensitivity, toxicity, and explosiveness increase
Solution Approach 1:
The patent changes the thermal parameter of the blowing agent from exothermic to endothermic decomposition. This fundamental parameter change eliminates the harmful exothermic reaction while maintaining the gas generation function, thereby resolving the safety and toxicity issues associated with conventional exothermic blowing agents.
Solution Approach 2:
The patent converts the previously harmful exothermic decomposition into a beneficial endothermic process. The endothermic decomposition not only eliminates safety hazards but also provides a cooling effect during expansion, which helps control the foaming process and reduces the risk of uncontrolled expansion.
2Quantity of substance
If exothermic blowing agents are used, then foaming occurs, but volatile organic compound content increases
Solution Approach 1:
The patent changes the decomposition temperature parameter of the blowing agent to below 100°C. This temperature parameter change ensures that the decomposition occurs at low temperatures where volatile organic compound formation is minimized, while still achieving adequate foam expansion for the application.
3Volume of moving object
If exothermic blowing agents are used, then expansion occurs at high temperatures, but water absorption increases
Solution Approach 1:
The patent changes the decomposition temperature parameter from high (140-220°C) to low (below 100°C). This temperature parameter change prevents the formation of large pores that would increase water absorption, while still achieving the required expansion volume through controlled low-temperature decomposition.
4Quantity of substance
If exothermic blowing agents are used, then foaming occurs, but foam structure consistency decreases with temperature variation
Solution Approach 1:
The patent changes the decomposition temperature parameter to below 100°C, which is below the curing temperature range. This ensures that the blowing agent decomposes completely before curing begins, eliminating the temperature sensitivity issue where partial decomposition at lower temperatures would lead to inconsistent foam structures. The low decomposition temperature provides a stable, consistent foam structure across the entire curing temperature range.
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 provides a safer, more efficient sealing and bonding method with reduced water absorption and consistent foam structure, enabling improved corrosion resistance and structural stability in automotive components without the hazards of exothermic agents.
Implementation Method 1
endothermic chemical blowing agents, specifically carboxylic acids and urea derivatives
Implementation Method 2
During decomposition, they also give rise to by-products such as ammonia, formamide, formaldehyde or nitrosamines
Implementation Method 3
at least one peroxidically cross-linking polymer, at least one peroxide
Data Source
AI summary
The present application relates to a thermally expandable composition containing at least one peroxide cross-linking polymer, at least one peroxide and at least one endothermic, chemical blowing agent, the blowing agent comprising at least one solid, optionally functionalized, polycarboxylic acid or the salt thereof and at least one urea derivative according to the formula (I) as defined herein; as well as shaped bodies containing the composition and to a method for sealing and filling voids in components, for strengthening or reinforcing components, in particular hollow components, and for bonding mobile components using shaped bodies of this type.