Heat-Expanded Microspheres Production Process
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Solution Overview
Problem
Heat-expanded microspheres have low packing efficiency and are prone to destruction under mixing stress, leading to poor durability and storage efficiency due to excessive expansion and thin shells.
Innovation Solution
The production process involves heating heat-expandable microspheres in a dry hot gas flow with a controlled temperature variation of no more than 40°C, using a turbulent flow generating member to ensure consistent expansion and minimize aggregation, resulting in microspheres with high packing efficiency and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If heat-expandable microcapsules are heated and expanded in dry hot gas flow, then the residual amount of unexpanded raw material is lowered and aggregation is minimized, but the packing efficiency remains low and void fraction is high
Solution Approach 1:
The patent applies parameter changes by precisely controlling the hot gas flow temperature (maintaining it between 80-150°C) and adjusting the concentration of heat-expandable microcapsules in the gas flow (0.1-10 g/m³). These parameter optimizations ensure uniform expansion while minimizing void fraction and improving packing efficiency of the resulting microspheres.
2Weight of moving object
If heat-expanded microspheres are made with larger expansion ratio, then lightweight property is improved, but shell thickness decreases and durability against repeated compression deteriorates
Solution Approach 1:
The patent optimizes the expansion parameters by controlling hot gas temperature (80-150°C) and microcapsule concentration (0.1-10 g/m³) to achieve an optimal expansion ratio that balances lightweight properties with shell integrity. This ensures the microspheres maintain sufficient shell thickness to withstand repeated compression while still providing lightweight characteristics.
3Use of energy by moving object
If hot gas flow temperature varies widely, then heating efficiency may increase, but expansion uniformity decreases and aggregated microspheres are formed
Solution Approach 1:
The patent implements temperature control feedback by monitoring and maintaining hot gas flow temperature within the specific range of 80-150°C. This feedback control ensures uniform heating of microcapsules without excessive temperature variations, preventing aggregation while maintaining efficient expansion.
Solution Approach 2:
The patent optimizes the hot gas temperature parameter (80-150°C) to achieve the best balance between heating efficiency and expansion uniformity. This parameter optimization prevents both insufficient expansion and excessive aggregation of microspheres.
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 method produces heat-expanded microspheres with improved packing efficiency, reduced aggregation, and enhanced durability against repeated compression, ensuring high flowability and consistent mass specific gravity.
Implementation Method 1
heating them at a temperature not lower than the expansion initiating temperature of the heat-expandable microspheres
Implementation Method 2
expanded microspheres by heating heat-expandable microspheres in a dry hot gas flow
Implementation Method 3
a blowing agent encapsulated therein having a boiling point not higher than the softening point of the thermoplastic resin
Data Source
Figure 1(a)~1(b)
Figure 2
Figure 3
AI summary
The present invention provides heat-expanded microspheres having high packing efficiency, and a production method thereof. The heat-expanded microspheres are produced by expanding heat-expandable microspheres, which comprise 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 micrometer, at a temperature not lower than their expansion initiating temperature, and the heat-expanded microspheres result in a void fraction not higher than 0.70.