X-ray or gamma ray systems or devices – Specific application – Fluorescence
Patent
1984-07-30
1987-10-06
Fields, Carolyn E.
X-ray or gamma ray systems or devices
Specific application
Fluorescence
378 45, 378 50, 378 53, 378 90, G01N 23223, G01N 3334
Patent
active
046988327
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention concerns a method for measuring the distribution in the thickness direction of filler and/or coating materials of paper, cardboard or the equivalent, and the contents of said materials without destroying the sample. In the method or procedure of the invention, the radiation emitted by an x-ray source is used to excite in the material component under examination of the object under measurement its characteristic x-ray radiation and the intensity of this radiation is observed. In procedure, measurements are carried out on both sides of the specimen under examination. In addition, the contents of other filler components are determined by x-ray radiation absorption measurements in order to eliminate the effects of such components interfering with the distribution measurement, and the base weight of the paper is determined by beta radiation absorption measurement, or by another equivalent procedure.
Furthermore, the present invention concerns apparatus for applying the method and novel uses of the procedure and the apparatus.
When paper and paper machines are discussed in the following, reference is generally made both to paper and cardboard, and respectively both to paper and cardboard machines.
Fillers, which as a rule are mineral substances, are incorporated in the paper primarily for their effect of improving the printing technological properties. Fillers are most commonly used for printing papers. The filler addition improves the opacity, lightness, printer's ink absorption and surface smoothness of the paper.
The fillers influence in a particularly advantageous manner the quality of paper to be glazed.
It is known in the art to add filler material in two ways, either by mass filling or by coating. In the mass filling method or procedure, the filler material is added in the form of suspension to the pulp sludge before the arrival of the sludge on the paper machine, whereby the filler material is admixed with the entire fiber material in the finished paper. In the coating procedure, a suitable glue substance is admixed with the filler material in the aqueous phase, such as starch or casein, whereafter the surface of the paper is brushed with this mixture in a continuous process.
The filler materials in paper tend to be non-uniformly distributed in the thickness direction of the paper, causing one-sidedness of the paper. The one-sidedness of paper manufactured on Fourdrinier machines is due to the fact that the fillers are washed out together with the water that is drained, from the lower part of the pulp web into the drainage water, whereby they become enriched in the upper part of the web. As is known in the art, efforts have been made to reduce the problems of one-sidedness, not only by additives improving the retention, but also by gentle dewatering at the initial draining phase, which requires a longer dewatering time and therefore implies lengthening the wire section or reducing the speed of the paper machine.
In machines with a planar wire, the difficulties with the fines and filler distribution manifest themselves when papers for offset printing are manufactured. A high filler and fines content on the top surface of the paper causes dusting, which is a serious detriment in the offset process. In contrast, papers manufactured on a twin wire machine are considered well appropriate for offset printing. This is due to the symmetrical shape of the fines distribution and to equal leaching of both surfaces of the web due to two-sided dewatering. It is in fact generally held that due to more uniform fines distribution, the printing by offset on paper manufactured on a twin wire machine is more successful than that on paper manufactured on a Fourdrinier machine. Offset printability has indeed increased in significance because offset printing is increasingly replacing the letterpress printing procedure.
On the other hand, the filler content of the surfaces of the paper web cannot always be brought to a desired level with a twin wire former. Even when planar wi
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patent: 3102952 (1963-09-01), Hendee et al.
patent: 3530296 (1970-09-01), Lehtinin et al.
patent: 3904876 (1975-09-01), Arendt
patent: 3914607 (1975-10-01), Cho et al.
patent: 4081676 (1978-03-01), Buchnea
patent: 4147931 (1979-04-01), Puumalainen
patent: 4350889 (1982-09-01), Lisnyansky
"Determination of Content and Distribution of Filler . . . ", J. Kuusi, Paperi Puu 52, No. 4a, p. 145-151, 154-158 (Apr. 1970).
English Abstract from Paperchem, Access No. 50-06512, Karton No. 3, 8(1979), "Monitoring Apparatus for Determining . . . "
English Abstract from Paperchem, Access No. 46-03646, Prom No. 17: 1974, pp. 123-126, "Use of X-rays for Determining . . . "
Fields Carolyn E.
Robotest Oy
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