CPC G01N 13/00 (2013.01) [C09D 11/38 (2013.01); G01N 24/08 (2013.01); G01R 33/448 (2013.01)] | 8 Claims |
2. A method for selecting a water-based printing ink based on low-field nuclear magnetic resonance (LF-NMR), comprising the following steps:
(1) acquiring LF-NMR echo signals of one or more water-based printing inks by using a Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence to obtain an echo attenuation curve, wherein the CPMG pulse sequence has the following parameters: 90° pulse width P1: 8.0 μs, 180° pulse width P2: 15 μs, waiting time: 12,000.00 ms, analog gain: 20.0, digital gain: 3, preamp gain: 1, number of scans: 4, number of echoes: 12,000, receiver bandwidth: 100 KHz, and radio frequency delay: 0.150 ms;
(2) deriving a spectral curve of a transverse relaxation time T2 by using an inversion algorithm thereof based on the echo attenuation curve; and
(3) determining moisture retention and/or fluidity of the water-based printing inks according to a peak area and a displacement of immobile water and free water in the spectral curve of the transverse relaxation time T2, and selecting a water-based printing ink with moisture retention and/or fluidity meeting a target value.
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