Hygroscopicity evaluation method and water content evaluation method

Patent metadata

Field	Value
Publication number	US-12442809-B2
Application number	US-202318095575-A
Country	US
Kind code	B2
Filing date	Jan 11, 2023
Priority date	Feb 14, 2022
Publication date	Oct 14, 2025
Grant date	Oct 14, 2025

Abstract

A hygroscopicity evaluation method includes: a first step of preparing a first sample and a second sample; a second step of acquiring a first detection result for the first sample and a second detection result for the second sample by making a terahertz wave incident on each of the first and second samples; and a third step of evaluating the hygroscopicity of a measurement target object based on a first frequency characteristic calculated from the first detection result and a second frequency characteristic calculated from the second detection result. In the third step, the magnitude of the hygroscopicity of the measurement target object is evaluated based on the difference between the magnitude of a first peak of the first frequency characteristic in a reference frequency range and the magnitude of a second peak of the second frequency characteristic in the reference frequency range.

First claim

What is claimed is:

1. A hygroscopicity evaluation method for evaluating hygroscopicity of a measurement target object containing a clay mineral, comprising:
a first step of preparing a first sample containing a first clay mineral as the clay mineral and a second sample containing a second clay mineral, which is the same as the first clay mineral, as the clay mineral;
a second step of acquiring a first detection result for the first sample by making a first terahertz wave incident on the first sample and detecting the first terahertz wave from the first sample and a second detection result for the second sample by making a second terahertz wave incident on the second sample and detecting the second terahertz wave from the second sample; and
a third step of evaluating the hygroscopicity of the measurement target object based on a first frequency characteristic of the first sample calculated from the first detection result and a second frequency characteristic of the second sample calculated from the second detection result,
wherein, in the first step, at least one of the first and second samples is subjected to a water absorption/dehydration treatment to prepare samples having different hygroscopicity, and
in the third step, a magnitude of the hygroscopicity of the measurement target object is evaluated based on a difference between a magnitude of a first peak of the first frequency characteristic in a reference frequency range and a magnitude of a second peak of the second frequency characteristic in the reference frequency range.

2. The hygroscopicity evaluation method according to claim 1 ,
wherein the clay mineral is montmorillonite or kaolinite.

3. The hygroscopicity evaluation method according to claim 1 , further comprising:
a fourth step of preparing the measurement target object selected based on the difference between the magnitude of the first peak and the magnitude of the second peak;
a fifth step of acquiring a detection result for the measurement target object by making a terahertz wave incident on the measurement target object and detecting the terahertz wave from the measurement target object; and
a sixth step of evaluating a water content of the measurement target object based on a frequency characteristic of the measurement target object calculated from the detection result,
wherein, in the sixth step, the water content of the measurement target object is evaluated based on first reference information indicating a relationship between a magnitude of a peak of a frequency characteristic of a reference sample in the reference frequency range and a water content of the reference sample and a magnitude of a peak of the frequency characteristic of the measurement target object in the reference frequency range.

4. The hygroscopicity evaluation method according to claim 3 ,
wherein, in the sixth step, interlayer water evaluation is performed to evaluate interlayer water contained in the measurement target object by using a differential value of the frequency characteristic of the reference sample in the reference frequency range as the magnitude of the peak of the frequency characteristic of the reference sample in the reference frequency range and using a differential value of the frequency characteristic of the measurement target object in the reference frequency range as the magnitude of the peak of the frequency characteristic of the measurement target object in the reference frequency range.

5. The hygroscopicity evaluation method according to claim 4 ,
wherein, in the sixth step, free water evaluation is further performed to evaluate free water contained in the measurement target object based on second reference information indicating a relationship between a frequency characteristic of the reference sample in a base frequency range different from the reference frequency range and a water content of the reference sample and a frequency characteristic of the measurement target object in the base frequency range.

6. The hygroscopicity evaluation method according to claim 3 , further comprising:
a seventh step of preparing a plurality of reference samples having different water contents, each of the plurality of reference samples being the reference sample;
an eighth step of acquiring a detection result for each of the plurality of reference samples by making a terahertz wave incident on each of the plurality of reference samples and detecting the terahertz wave from each of the plurality of reference samples; and
a ninth step of creating the first reference information based on a frequency characteristic of each of the plurality of reference samples calculated from the detection result and the water content of each of the plurality of reference samples,
wherein, in the ninth step, the first reference information is created based on a magnitude of a peak of the frequency characteristic of each of the plurality of reference samples in the reference frequency range and the water content of each of the plurality of reference samples.

7. The hygroscopicity evaluation method according to claim 6 ,
wherein, in the ninth step, a differential value of the frequency characteristic of each of the plurality of reference samples in the reference frequency range is used as the magnitude of the peak of the frequency characteristic of each of the plurality of reference samples in the reference frequency range.

8. The hygroscopicity evaluation method according to claim 1 ,
wherein, in the second step, a terahertz wave attenuated total reflection spectroscopy is used.

9. The hygroscopicity evaluation method according to claim 1 ,
wherein, the first terahertz wave incident and the second terahertz wave incident are different terahertz wave incidents.

10. A water content evaluation method for evaluating a water content of a measurement target object containing a clay mineral, comprising:
a first step of preparing the measurement target object;
a second step of acquiring a detection result for the measurement target object by making a terahertz wave incident on the measurement target object and detecting the terahertz wave from the measurement target object; and
a third step of evaluating the water content of the measurement target object based on a frequency characteristic of the measurement target object calculated from the detection result,
wherein, in the third step, the water content of the measurement target object is evaluated based on first reference information indicating a relationship between a magnitude of a peak of a frequency characteristic of a reference sample in a reference frequency range and a water content of the reference sample and a magnitude of a peak of the frequency characteristic of the measurement target object in the reference frequency range.

11. The water content evaluation method according to claim 10 ,
wherein, in the third step, interlayer water evaluation is performed to evaluate interlayer water contained in the measurement target object by using a differential value of the frequency characteristic of the reference sample in the reference frequency range as the magnitude of the peak of the frequency characteristic of the reference sample in the reference frequency range and using a differential value of the frequency characteristic of the measurement target object in the reference frequency range as the magnitude of the peak of the frequency characteristic of the measurement target object in the reference frequency range.

12. The water content evaluation method according to claim 11 ,
wherein, in the third step, free water evaluation is further performed to evaluate free water contained in the measurement target object ba

Assignees

• Hamamatsu Photonics Kk

Inventors

• Uchida Tetsuya
• Akiyama Kouichiro
• Satozono Hiroshi
• Hakamata Tomoyuki

Classifications

• G01N21/552

  Attenuated total reflection · CPC title

• G01N21/3581

  using far infrared light; using Terahertz radiation · CPC title

• G01N33/246 Primary

  for water content · CPC title