Pressure Measurement Material Composition Using Segmented Microcapsules
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Solution Overview
Problem
Conventional pressure measurement materials struggle to detect pressure differences below 0.05 MPa, leading to insufficient color formation and density gradation, and are prone to unnecessary color formation due to rubbing during handling.
Innovation Solution
A material composition for pressure measurement featuring a color forming layer with microcapsules A encapsulating an electron-donating colorless dye precursor and microcapsules B not encapsulating the dye precursor, where the volume standard median diameters satisfy specific ratios and ranges, and a coefficient of variation of particle size distribution is maintained within 35% to 150%, to achieve excellent color developability and suppress unwanted color formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensitivity is increased to detect minute pressure below 0.05 MPa, then color formation at low pressure is improved, but color formation due to rubbing during handling occurs
Solution Approach 1:
The microcapsule population is segmented into multiple size groups with different rupture pressures. Small microcapsules (D50: 10-30 μm) rupture at low pressure (0.01-0.05 MPa) to provide sensitivity, while large microcapsules (D50: 40-80 μm) remain intact during normal handling but rupture at higher pressure, providing a threshold effect that prevents false color formation from light rubbing
Solution Approach 2:
Different regions of the microcapsule size distribution are assigned different functions: small microcapsules provide the sensitive response to minute pressure, while large microcapsules provide mechanical robustness and prevent spurious color formation during handling. The wall thickness of microcapsules is also optimized locally, with thinner walls in smaller capsules for lower rupture pressure and thicker walls in larger capsules for higher rupture pressure
2Measurement precision
If color formation density difference is increased to enable visual recognition at 0.05 MPa, then detection capability is improved, but density gradation becomes difficult to obtain
Solution Approach 1:
The microcapsule population is divided into multiple size fractions, each contributing to different levels of pressure response. This segmentation creates a progressive color development across different pressure zones, enabling both sufficient density difference for visual detection and smooth density gradation for pressure differentiation
Solution Approach 2:
The invention optimizes multiple parameters simultaneously: microcapsule size distribution (D50: 10-80 μm with specific ratios), wall thickness variations, and dye precursor concentration. These parameter changes work together to achieve a balance where color formation is sufficiently dense for visual recognition while maintaining smooth gradation across the pressure 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 enables effective color formation and density gradation at minute pressures below 0.05 MPa while minimizing color formation due to rubbing, providing accurate pressure measurement with improved sensitivity and reduced unwanted color formation.
Implementation Method 1
microcapsules A encapsulating an electron-donating colorless dye precursor
Data Source
AI summary
Provided are a material for pressure measurement, including a color forming layer that contains microcapsules A encapsulating an electron-donating colorless dye precursor and microcapsules B not encapsulating an electron-donating colorless dye precursor, in which a volume standard median diameter D50A of the microcapsules A and a volume standard median diameter D50B of the microcapsules B satisfy Equation 1; a material composition for pressure measurement; and a material set for pressure measurement:D50A<D50B Equation 1.