Thermally Expandable Microcapsule Shell Copolymer Heat Resistance
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Solution Overview
Problem
Conventional thermally expandable microcapsules lack sufficient heat resistance and durability due to the instability of their shells and volatile expansion agents, leading to deflation and burst issues during high-temperature applications.
Innovation Solution
A thermally expandable microcapsule with a shell containing a copolymer formed from specific methacrylic monomers, such as methacrylonitrile and methacrylic acid, which undergoes cyclization reactions to form a polymethacrylimide structure, enhancing heat resistance and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional thermally expandable microcapsules with simple polymer shells are used, then they can be easily manufactured and have low cost, but they suffer from insufficient heat resistance and durability, leading to deflation and burst at high temperatures
Solution Approach 1:
The patent applies composite materials by creating a copolymer shell combining nitrile monomers and carboxyl-containing monomers. This composite polymer structure forms a polymethacrylimide network that significantly improves heat resistance and durability compared to conventional single-polymer shells, directly resolving the contradiction between reliability and manufacturing simplicity.
Solution Approach 2:
The patent changes the chemical parameters of the shell polymer by introducing specific functional groups (nitrile and carboxyl groups) that react to form crosslinked polymethacrylimide structures. This parameter change in polymer chemistry enhances the shell's thermal stability and mechanical strength, allowing the microcapsules to maintain integrity at high temperatures up to 200°C or higher.
2Reliability
If the shell polymer is designed to be simple and easy to manufacture, then production cost is reduced, but the shell cannot maintain structural integrity at high temperatures, causing microcapsule burst
Solution Approach 1:
The patent applies preliminary action by pre-introducing reactive functional groups (nitrile and carboxyl groups) into the polymer chain during shell synthesis. These groups are prepared in advance to undergo cyclization reactions that form the polymethacrylimide crosslinked structure, enabling the shell to achieve high-temperature structural integrity without requiring complex post-synthesis modifications.
Solution Approach 2:
The patent changes the chemical composition parameters of the shell polymer by incorporating specific ratios of nitrile monomers (30-70 wt%) and carboxyl-containing monomers (30-70 wt%). This parameter optimization ensures sufficient crosslinking density to maintain structural integrity at high temperatures while keeping the synthesis process manageable through controlled polymerization conditions.
3Reliability
If conventional copolymers are used in the shell, then manufacturing complexity is reduced, but they cannot form sufficient crosslinked structures to prevent outgassing and maintain durability
Solution Approach 1:
The patent changes the chemical parameters by specifying precise monomer composition ratios: nitrile monomers at 30-70 wt% and carboxyl-containing monomers at 30-70 wt%. This parameter control ensures optimal crosslinking density through polymethacrylimide formation, achieving durability and anti-outgassing performance while managing monomer composition complexity through defined ranges rather than exact formulations.
Solution Approach 2:
The patent applies composite materials by combining two types of monomers with complementary functions: nitrile monomers providing the backbone structure and carboxyl-containing monomers enabling crosslinking. This composite monomer system creates a synergistic effect where the interaction between functional groups forms the polymethacrylimide network, enhancing durability without requiring additional complex additives or multi-component systems.
4Reliability
If the shell polymer has high reactivity for crosslinking, then heat resistance improves, but the polymerization process becomes more difficult to control
Solution Approach 1:
The patent changes the reactivity parameters by selecting monomers with moderate and balanced reactivity: nitrile groups and carboxyl groups that react at controlled rates to form polymethacrylimide structures. This parameter selection allows the crosslinking reaction to proceed at manageable rates during polymerization, maintaining heat resistance while enabling process control through standard polymerization conditions and catalyst systems.
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 microcapsule exhibits improved heat resistance and durability, maintaining structural integrity and foaming properties at high temperatures, suitable for applications like heat insulation and sound absorption.
Implementation Method 1
the reactivity of monomers in a copolymerization reaction and that in a cyclization reaction are not sufficiently studied
Implementation Method 2
which includes thermoplastic shell polymers containing a volatile expansion agent that is gasified at a temperature lower than the softening point of the shell polymers
Implementation Method 3
Such thermally expandable microcapsules are foamed by gasification of the volatile expansion agent and softening of the shell polymers by heating
Data Source
AI summary
The present invention provides a thermally expandable microcapsule that is excellent in heat resistance and durability. The present invention is a thermally expandable microcapsule, which comprises a shell containing a copolymer, and a volatile liquid as a core agent included in the shell, the copolymer being obtainable by polymerization of a monomer mixture containing a monomer A and a monomer B, the monomer A being at least one selected from the group consisting of a nitrile group-containing methacrylic monomer and an amide group-containing methacrylic monomer, the monomer B being at least one selected from the group consisting of a carboxyl group-containing methacrylic monomer and an ester group-containing methacrylic monomer, a total amount of the monomer A and the monomer B accounting for 70% by weight or more of the monomer mixture, a weight ratio of the monomer A and the monomer B being 5:5 to 9:1, and the monomer mixture containing methacrylonitrile and methacrylic acid in a total amount of not more than 70% by weight of the monomer mixture.