Method and device for measuring basis weight and moisture content amount

摘要

A resonance frequency shift amount Δf and a peak level change amount ΔP are measured using a microwave resonator, V1 and V2 are obtained based on V1=(Δf·∈″2/Kf−ΔP·∈′2/Kp)/(∈′1·∈″2−∈″1·∈′2), and V2=(Δf·∈″1/Kf−ΔP·∈′1/Kp)/(∈″1·∈′2−∈′1·∈″2), and an absolute dry basis weight and a moisture amount are obtained based on absolute dry basis weight=β·V1, and moisture amount=γ·V2. For the constants Kf, Kp, ∈′1, ∈′2, ∈″1 and ∈″2, the constants ∈′1, ∈′2, ∈″1 and ∈″2 are determined so that the variance values of Kf and Kp are smaller than a predetermined value.

主权项

1. A method of measuring basis weight and moisture amount for calculating a basis weight and a moisture amount of a sample constituted by a paper sheet using a microwave resonator, the method comprising the steps S1 to S6 of;
(Step S1) obtaining a resonance frequency and a resonance peak level of the microwave resonator in a case without a sample; (Step S2) obtaining a resonance frequency and a resonance peak level of the microwave resonator in the case where the sample is measured; (Step S3) obtaining a resonance frequency shift amount Δf as a difference between the resonance frequency obtained in the step S1 and the resonance frequency obtained in the step S2; (Step S4) obtaining a peak level change amount ΔP as a difference between the resonance peak level obtained in the step S1 and the resonance peak level obtained in the step S2; (Step S5) obtaining V1 and V2 using expressions:
V1=(Δf·∈″2/Kf−Δp·∈′2/Kp)/(∈′1·∈″2−∈″1·∈′2)  (3); andV2=(Δf·∈″1/Kf−Δp·∈′1/Kp)/(∈″1·∈′2−∈′1·∈″2)  (4); (Step S6) obtaining an absolute dry basis weight and a moisture amount using expressions:
Absolute Dry Basis Weight=β·V1  (5); andMoisture Amount=γ·V2  (6),wherein
V1: a volume of absolute dry paper under a certain condition; V2: a volume of water under a certain condition; Kf: a proportional constant for matching dimensions; Kp: a proportional constant for matching dimensions; ∈′1: a dielectric constant of the absolute dry paper−1; ∈′2: a dielectric constant of the water; ∈″1: a dielectric loss factor of the absolute dry paper; ∈″2: a dielectric loss factor of the water; and β, γ: proportional constants, and the constants Kf, Kp, ∈′1, ∈′2, ∈″1, and ∈″2 are determined through the following steps A and B, and the constants β and γ are previously determined: (Step A) for each of a plurality of standard samples having different values for one of the basis weight and the moisture amount, measuring the resonance frequency shift amount Δf and the peak level change amount ΔP by a measurement apparatus using the microwave resonator through the steps S1 to S4; and (Step B) obtaining ∈′1, ∈′2, ∈″1, and ∈″2 when variance values of Kf and Kp are smaller than a predetermined value in the relation of the expressions (3) and (4), by taking V1=BD/β and V2=WT/γ, BD being a predetermined absolute dry basis weight of each of the standard samples and WT being a predetermined moisture amount of each of the standard samples, and by using Δf and ΔP obtained in the step A.