Heat-Expanded Microspheres Uniform Particle Size Distribution
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Solution Overview
Problem
Existing processes for producing heat-expanded microspheres result in non-uniform particle size distribution, high aggregation, and poor resistance to external forces, leading to issues like hardening, shrinking, and thermal deflation in porous materials, and inadequate sealing and pressure retention in tire-and-rim assemblies.
Innovation Solution
A production process involving the controlled expansion of heat-expandable microspheres with a specific fluorine compound, ensuring minimal aggregation and high true specific gravity, and the use of a thermoplastic resin with a nitrile monomer and carboxyl group-based polymerization, along with an anti-blocking agent, to achieve uniform particle size distribution and enhanced durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If heat-expandable microspheres are expanded in hot gas spray or conventional processes, then expansion is achieved, but particle size distribution becomes non-uniform and aggregation increases
Solution Approach 1:
The patent applies preliminary action by pre-dispersing the heat-expandable microspheres in a carrier fluid before expansion, and pre-positioning a dispersion nozzle within the hot gas flow path. This ensures uniform distribution is established before the expansion process begins, preventing aggregation during expansion.
Solution Approach 2:
The patent uses a carrier fluid as an intermediary medium to disperse the heat-expandable microspheres before they encounter the hot gas. The dispersion nozzle acts as an intermediary device that introduces the microspheres uniformly into the hot gas flow, preventing direct aggregation that would occur in conventional spray processes.
2Weight of moving object
If heat-expandable microspheres are expanded to high volume, then weight reduction is achieved, but resistance to external force decreases
Solution Approach 1:
The patent applies parameter changes by optimizing the expansion conditions (temperature, time, hot gas flow rate) to achieve a balanced expansion state. The microspheres are expanded to sufficient volume for weight reduction while controlling the expansion parameters to maintain shell integrity and resistance to external forces.
Solution Approach 2:
The patent uses composite materials by incorporating a shell made from thermoplastic resin with specific composition (containing nitrile groups and carboxyl groups) that provides both the necessary expandability for weight reduction and the mechanical strength for resistance to external forces. The shell composition is engineered as a composite structure balancing these opposing requirements.
3Weight of stationary object
If porous material composition is molded with heat-expanded microspheres, then lightweight structure is achieved, but hardening and shrinkage occur
Solution Approach 1:
The patent applies preliminary action by pre-expanding the microspheres to their final or near-final volume before incorporation into the porous material composition. This prevents further expansion or shrinkage during the molding process, maintaining dimensional stability while achieving the desired lightweight structure.
Solution Approach 2:
The patent applies parameter changes by controlling the molding process parameters (temperature, pressure, time) to remain within a range that does not trigger further expansion or collapse of the microspheres. The molding conditions are optimized to match the pre-expanded state of the microspheres, preventing hardening and shrinkage.
4Productivity
If conventional expanding processes are used, then production speed is maintained, but time-dependent thermal deflation occurs
Solution Approach 1:
The patent applies parameter changes by optimizing the expansion temperature, time, and hot gas composition to achieve complete and stable expansion. This eliminates the time-dependent thermal deflation that occurs in conventional processes where incomplete expansion leads to continued deflation over time. The expanded microspheres maintain their volume stably at service temperatures.
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 process produces heat-expanded microspheres with low aggregation and high true specific gravity, preventing hardening and shrinking in porous materials, maintaining dimensional stability, and providing effective sealing and pressure retention in damaged tires.
Implementation Method 1
heat-expandable microspheres comprising a structure of a shell of thermoplastic resin and a blowing agent encapsulated therein
Implementation Method 2
heating and expanding the heat-expandable microspheres
Implementation Method 3
heating the dispersed heat-expandable microspheres in the hot gas flow at a temperature not lower than their expansion initiating temperature
Data Source
AI summary
A production process for heat-expanded microspheres includes the step of providing a gaseous fluid containing heat-expandable microspheres, which includes a shell of thermoplastic resin and a blowing agent encapsulated therein having a boiling point not higher than the softening point of the thermoplastic resin and have an average particle size from 1 to 100 μm. The gaseous fluid is fed through a gas-introducing tube having a dispersion nozzle on its outlet that is fixed inside a conduit having a hot gas flow flowing therethrough. A jet of the gaseous fluid is emitted through the dispersion nozzle. Further, the gaseous fluid is collided on a collision plate fixed under the dispersion nozzle so as to disperse the heat-expandable microspheres in the hot gas flow. The dispersed heat-expandable microspheres are heated in the hot gas flow at a temperature not lower than their expansion initiating temperature and thus expanded.