Thermally Expandable Bulkhead Sealant Without Carrier
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Solution Overview
Problem
Existing thermally expandable bulkhead parts for sealing cavities in vehicles face challenges with inconsistent expansion rates due to varying temperatures and lack of stability during the curing process, often resulting in incomplete sealing or collapse under gravity without a carrier structure.
Innovation Solution
A thermally expandable preparation comprising at least 40% peroxidically crosslinkable binary copolymer, 0.2-2% peroxide, 5-18% chemical blowing agent, and 2-20% polymer based on diene monomers, which expands uniformly across a wide temperature range without collapsing, even without a carrier material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If thermally expandable bulkhead parts are used without a carrier structure to simplify production, then manufacturing complexity is reduced, but the preparation collapses under gravity during curing
Solution Approach 1:
The patent modifies the chemical composition parameters of the thermally expandable preparation by incorporating specific polymers (polyethylene, polypropylene), blowing agents (azodicarbonamide, ammonium bicarbonate), and crosslinking agents (silane-modified polymers) in controlled ratios. These parameter changes enable the preparation to achieve sufficient structural integrity and resistance to gravitational collapse during curing, eliminating the need for a carrier structure while maintaining reliability.
2Adaptability or versatility
If high expansion rates are achieved to seal cavities with varying geometries, then adaptability is improved, but the preparation becomes unstable during curing
Solution Approach 1:
The patent employs a composite material system combining multiple polymers (polyethylene, polypropylene, silane-modified polymers), various blowing agents (azodicarbonamide, ammonium bicarbonate, sodium aluminum carbonate sulfate), and crosslinking agents. This composite formulation achieves high expansion rates (sufficient to seal cavities with varying geometries) while maintaining curing stability through the synergistic interaction of components that control gas generation, foam cell formation, and crosslinking kinetics.
Solution Approach 2:
The patent optimizes the compositional parameters including the ratios of different polymers, blowing agents, and crosslinking agents. Specific parameter ranges are established to balance expansion rate and curing stability, allowing the preparation to adapt to various cavity geometries while remaining stable during the curing process in automotive ovens.
3Reliability
If the preparation is designed to expand at high temperatures to ensure complete sealing, then sealing reliability is improved, but the preparation loses stability and collapses
Solution Approach 1:
The patent carefully controls the thermal decomposition parameters of the blowing agents and the crosslinking temperature profile. By selecting blowing agents with appropriate decomposition temperatures (azodicarbonamide, ammonium bicarbonate, sodium aluminum carbonate sulfate) and incorporating crosslinking agents that activate at specific temperatures, the preparation achieves complete cavity sealing through high-temperature expansion while maintaining structural stability and preventing collapse through concurrent crosslinking.
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 achieves high expansion rates with stability during the curing process, ensuring reliable sealing of cavities with varying geometries and maintaining structural integrity under different temperature conditions, preventing collapse and ensuring complete sealing without the need for a carrier material.
Implementation Method 1
0.2 to 2% by weight of at least one peroxide
Implementation Method 2
at least one peroxidically crosslinkable binary copolymer
Implementation Method 3
5 to 18% by weight of at least one chemical blowing agent
Implementation Method 4
expansion rates of up to 1000%
Implementation Method 5
2 to 20% by weight of at least one polymer based on one or more diene monomers
Implementation Method 6
at least one terpolymer based on at least one first monomer, selected from the mono- or polyunsaturated hydrocarbons, and at least one second monomer, selected from the (meth) acrylic acids and their derivatives
Data Source
AI summary
The present specification relates to thermally expandable formulations comprising: (a) at least one peroxidically crosslinkable binary copolymer comprising at least one monomer unit selected from vinyl acetate, (meth)acrylic acids and derivatives thereof, the binary copolymer having a melt flow index of not more than 3 g/10 min, as determined in accordance with DIN EN ISO 1133 and with a test load of 2.16 kg and a test temperature of 190°C; (b) at least one peroxide; (c) at least one chemical blowing agent; (d) at least one polymer based on one or more diene monomers; and (e) at least one terpolymer based on at least one first monomer selected from singly or multiply unsaturated hydrocarbons, and on at least one second monomer selected from (meth)acrylic acids and derivatives thereof.