SU722496A3 - Method of producing multilayer fibrous rolled materials - Google Patents

Abstract

1376518 Manufacture of fibre sheets KARLSTADS MEKANISKA WERKSTAD AB 13 Oct 1972 [15 Oct 1971] 47235/72 Heading D2A In the manufacture of fibre sheets, e.g. paper, using an initial fibre-stock suspension containing B.O.D., (biochemical oxygen dem- and) substances, the suspension is divided into flows 5, 6, the flow 5 is conveyed to a first sheet forming stage 7 in which a first layer 8 is formed, the flow 6 is subjected to a washing process 9 in which the original B.O.D. substances containing suspension water is replaced by water substantially free of these substances, the washed flow 11 is conveyed to a second sheet forming stage 13 and optionally to a third sheet forming stages 14 where layers are formed which are added to the layer 8, and the water removed in the first sheet forming stage 7 and the original B.O.D. substances containing suspension water from the washing process 9 is recirculated to the initial fibre-stock suspension. Wood associated with water is ground to a pulp at 1; the pulp being then screened at 3 with the recirculated water entering at 4. The water from the second and third forming stages 13, 14 and from a pressing stage 17 is recirculated to the washing process at 10. The three layered web 18 has the layer 8 as the centre layer and passes from the pressing stage 17 to a dryer (not shown). Clean water is supplied at 19 for cleaning, the press felts. Chemical wood-pulp may be added at 20. The layer 8 may be dewatered in forming stage 7 to a value such that its water content does not exceed the total water content of the three layered web 18, to prevent B.O.D. substances reaching the outer surfaces of the web during pressing. A web of more than three layers may be produced and this may be of cardboard or fibreboard. A paper-making machine for forming a three-layered web, Fig. 2 (not shown), has three successively disposed sheet forming double wire sections and a press section, the first forming section having a pervious forming suction roll, and the other two forming sections have impervious forming rolls which avoid dewatering through the first layer containing B.O.D. substances. The headboxes for the second and third forming sections are directed to one side of the previously formed layer or layers so as not to disturb these.

Description

one

This invention relates to papermaking technology and can be used in the pulp and paper industry.

Methods are known for producing multi-layered fibrous roll materials by grinding wood pulp, sorting and molding a web.

The purpose of the invention is to improve the quality of the cover layers of the web.

This is achieved by the fact that according to the proposed method, part of the fiber suspension after sorting is fed to the molding of one layer of the web, and the rest is washed to remove biochemically oxygen-consuming substances and the surface layers of the web are fed to the molding.

The diagram shows an embodiment of the method, with thin lines showing water, fresh and circulating and double lines - fibrous suspension.

the pulp obtained on the grinding equipment 1 is fed to sorting 2, from where part of it, containing biochemically oxygen-consuming substances.

is fed to the first stage 3 of the molding, and thus the first web layer is obtained. The remaining part of the pulp after sorting 2 is subjected to washing 4, as a result of which biochemically oxygen-consuming substances are removed from it, and fed to the second 5 and third 6 stages of web forming. These layers are coverslips with respect to the first layer obtained in stage 3, and due to the absence of biochemically oxygen-consuming substances in the cover layers, they do not turn yellow and retain high optical properties. The multi-layered web formed in stages 3, 5 and 6 of the molding is fed to the press section 7. The circulating water after the first molding stage is again fed to the grading, and the circulating water from the second and third molding stage, as well as after the pressing stage, is fed due to which the total water consumption is reduced. Thus, fresh water is required only for grinding wood and for washing the cloth in the press section.

Claims (1)

Invention Formula Method for the production of multilayer fibrous roll materials by grinding wood pulp, sorting and shaping the web, which is the fact that, in order to improve the quality of the coating the layers of the web, the fiber suspension after sorting serves to form one layer of the web, and the rest is washed to remove biochemically oxygen-consuming substances and is fed to the molding of 1 hem blood layer together with the first layer.