Optics: measuring and testing – Of light reflection
Patent
1995-12-06
1997-12-16
Font, Frank G.
Optics: measuring and testing
Of light reflection
356369, G01N 2155, G01J 400
Patent
active
056991630
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method of determining the orientation of fibers on the surface of a variety of paper such as PPC paper used with copiers, continuous form paper used with line printers for computers, etc., and paper material of which coated paper for posters is made.
BACKGROUND TECHNIQUE
As a measure of determining the properties of finished paper, the orientation of fibers has so far been widely used.
This fiber orientation of paper is generally represented by the angle of fiber orientation of paper and the intensity of orientation of paper fibers. By the former is meant the average direction in which fibers are arranged side by side, (viz., the direction in which the maximum number of fibers are arranged side by side). Here assume that the lengthy direction of a paper machine is zero degree. Then, the clockwise direction toward the downstream side of the paper machine is represented by the orientation angle of a plus (+) sign and the counterclockwise direction by the orientation angle of a (-) minus sign. By the latter is meant the ratio of the number of fibers arranged in the direction at right angles with the thus represented orientation angle of fibers (in which direction the minimum number of fibers are usually arranged) and the number of fibers arranged at that orientation angle of fibers. (This ratio is called the orientation ratio).
Such fiber orientation of paper correlates closely with paper strength or paper defects such as curling, warping or twisting etc. For example, this has close relations to PPC characteristics (the ability of cut paper sheets of small size to be received in the tray of a plain paper copy machine before copying or the ability of such sheets to be stacked one upon another or sorted after copying), running stability on fast printers or processors which becomes worse when paper sheets are fed in zigzag or other irregular ways, NIP characteristics (the ability of continuous form paper sheets used with a non-impact printer to be stacked one upon another after printing), etc.
Typically, the fiber orientation of paper has often been determined by obtaining test specimens at various angles with respect to the lengthy direction of a paper machine and measuring their tensile strengths at various angles with respect to the lengthy direction of a paper machine by tensile testing. With this method, however, much time is needed for obtaining data because the operation to obtain a number of test specimens is required and also tensile testings are needed as many as such specimens. In other words, a grave problem with this method is that data about the fiber orientation of paper measured cannot be fed back to meet the paper of the desired properties within an acceptably short time by adjusting the paper-making or processing conditions.
For eliminating such a problem and so measuring the fiber orientation of paper within a relatively short time, an apparatus--called a molecular orientation analyzer (available under the trade name of MOA-2001 manufactured by Kanzaki Seishi Co., Ltd.) is proposed and practically used so as to direct linearly polarized microwaves vertically to the paper sheet to be measured, thereby finding the fiber orientation of the sheet from the amount of attenuation of the output obtained through the sheet, as disclosed in Japanese Laid-Open Patent No. 60-227156. Another apparatus for determining the fiber orientation of a sheet from the angle distribution of the speed of propagation of ultrasonic waves, for instance, an apparatus available under the trade name of (SST-3000 manufactured by Nomura Shoji Co., Ltd.), is proposed and put to practical use.
However, none of the above-mentioned apparatus for determining the fiber orientation of paper within a relatively short time can be used for the purpose of determining the orientation of fibers present on the paper surface alone, because they are designed to use a medium transmitting through the paper to find the orientation of fibers throughout the entire layer of the paper in the for
REFERENCES:
patent: 3807868 (1974-04-01), Simila
patent: 5317387 (1994-05-01), Van Hengel et al.
Journal of Pulp and Paper Technology Association, vol. 48, No. 3, pp. 456-460, Mar. 3, 1994, Kiyokazu Sakai, et al., "On-Line Fiber Orientation Measuring System for Papers" (with partial English translation.
International Paper Physics Conference Book 1, pp. 81-87, 1991, Pierre Bernard, et al., "Probing Fiber Orientation Distribution Via Ellipsometric Measurements in the Far Infrared" (no month available).
Abe Yuji
Sakamoto Akira
Takeuchi Nobuo
Todoroki Hidenobu
Font Frank G.
Merlino Amanda
Nippon Paper Industries Co. Ltd.
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