FI57995C - FOERFARANDE FOER FRAMSTAELLNING AV BANFORMAT FIBERMATERIAL - Google Patents

Description

[B] (11) NOTICE OF ADVERTISEMENT -

Mft 1 J k} UTLÄGGNINGSSKRIFT 57995 C Patent oyonnotty 10 11 1980

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Patent and Registration Office NihtMiai, * ™ ,. kuLjuitaaun p * m.-

Patant- och registerstyrelsen AmMcm utlagd och uti. * Kri »Un pubUcored 31.07.80 (32) (33) (31) Pyydetty etuolkeu * —Bofird prlerltec (71) Tsentralny Nauchno-Issledovatelsky Institut Bumagi, Poselok Pravdinsky 15/1, Moskovskaya oblast ,

Tsentralny Nauchno-Issledovatelsky i Proektno-Konstruktorsky Institut po Proektirovaniju Oborudovania Tselljulozno-Bumazhnoi Promyshlennosti "Tsniibummash", Dvortsovaya Ploschad 6/8, Leningrad, USSR (SU), 72, Sergei Vyacheslavovich Petrovich Muraviev, Moskovskaya oblast, Valery Nikolaevich Nepein, Moskovskaya oblast,

Mikhail Vladimirovich Frolov, Moscow, Sergei Arnoldovich Aizenberg, Leningrad, Evgeny Mikhailovich Golovko, Leningrad, Alexandr Fedorovich Kamenev, Leningrad, Igor Alexandrovich Sergeev, Leningrad, USSR (SU) (7 * 0 Oy Kolster Ab (5 ^) Manufacture of web-like fibrous material for fram-staining of bandformat fibermaterial

The invention relates to the production of web-like fibrous materials, such as paper, board, nonwovens, and in particular to a process for their production.

An aerodynamic process for the production of fibrous materials is already known in the art, in which a fibrous raw material having an absolute moisture content of $ 5-100 or more by weight of completely dry fibers and these fibers is $ 95-50 and less is expressed as the concentration of fibers in the pulp. as discrete fibers which, in order to produce a mixture of air-materials, are fed to a stream of air which, when directed, is fed to a moving screen of a shaping chamber.

The fibers are then distributed on a sieve by mechanical disintegration of the mixture. The fibrous material is formed on a moving screen by causing the fibers to settle from the air-material mixture above and below the screen under the effect of an effective pressure difference.

After a uniform layer of fibrous material has formed on the moving screen, this layer is mechanically compacted, after which the compacted material is dried and finished.

2 57995

Due to the high concentration of the original fibrous material ($ 95-50), this known method cannot generate enough steam to disintegrate the condensed lumps in the step where the air-material mixture is introduced into the shaping chamber. This known method thus does not cause the fibers to be sufficiently decomposed or thoroughly distributed in the stream. This disadvantage, in turn, damages the quality of the finished fibrous material, which is characterized by too uneven distribution of the fibers and thus low tensile strength. This also leads to the slow formation of the material, the poor efficiency of the production equipment and the narrow range of products manufactured. This known method can therefore only be used for the production of paperboard.

Attempts have been made to eliminate the above-mentioned disadvantages by developing a method which has improved the uniform distribution of the fibers in the finished web material and increased its tensile strength. The starting material for this method has been wood pulp subjected to mechanical and heat treatment at 100 ° C and above to a moisture content of $ 30 or more, with a fiber concentration of $ 70 or less.

The mass having the above-mentioned moisture content is mixed into the gas stream so as to form an air-material mixture, which is then directed into the shaping chamber and shaped in the same manner as described above.

According to the applicant, the heat treatment of the fibrous raw material as described above smooths out the variations in the moisture content of the fibers in the shaping chamber, which has a positive effect on the even distribution of the fibers in this chamber and in the finished web-like fibrous material. This in turn improves the tensile strength of the material somewhat.

However, due to the relatively low moisture content of the fibrous raw material, this method is not fully efficient for producing a high tensile fibrous material and achieving a high forming speed.

In addition, both of the methods described above are quite complex because they involve a number of separate sequential steps, such as dispersing the fibers, forming an air-material mixture, and splitting the fibers in this mixture.

It is an object of the invention to obviate the above-mentioned disadvantages. The main object of the invention is therefore a method for producing web-like fibrous materials from such raw materials, which, due to the production and subsequent processing in the forming chamber, ensures a high forming speed and a wide range of finished materials, characterized by high tensile strength and low cost.

The invention thus relates to a process for producing a web-like material from a moist fibrous raw material by heating this material to a temperature of 102-145 ° C at a pressure of 111-405 kPa and decomposing it in a shaping chamber under reduced pressure, then forming an air mixture, dividing the fibers into a shaping chamber and is formed by the moving wire of the forming cage by causing the fibers to settle from the air mixture under the effect of the pressure difference above and below the moving wire, followed by mechanical sealing, drying and finishing. The method is characterized in that a fiber suspension with a fiber concentration of 5-30% by weight is used as a wet -1 -3 fibrous raw material and the shaping chamber pressure is reduced to 81-101 kPa in 10-10 seconds to ensure simultaneous distribution of fibers in the vapor air medium and air. - the formation of a mixture of substances and the even distribution of the fibers in the mixture.

The invention is mainly based on the following: the use of a suspension of fibrous material in which the concentration of fibers varies from 5 to 30% causes the formed web material to produce the moisture content necessary to form hydrogen bonds during the drying treatment, these bonds increasing the tensile strength of the fibrous material.

Due to the high strength achieved by the finished fibrous material, it is possible to do without binders, i.e. without both synthetic and some natural binders, such as casein, starch, etc., which lowers the price of the finished products.

By heating a suspension of fibrous material with a fiber concentration of 5-30% by weight to 102-145 ° C, a pressure of 111-405 kPa is obtained in this suspension. This pressure is sufficient to transport the pulp towards the shaping cavity.

Sudden reduction of the pressure from 111-405 kPa to 81-101 kPa increases the active surface area of the fibers and thus also increases the rate of material formation.

This involves a sudden expansion of the steam contained in the fiber suspension in the shaping chamber, which breaks up the lumps in the suspension into separate fibers and causes these fibers to be evenly distributed in the shaping chamber, thereby simultaneously forming an air-material mixture.

This has made it possible to combine processing steps such as breaking up the fibrous material into separate fibers, forming an air-material mixture, and evenly distributing the fibers in the chamber.

Combining these work steps in the material shaping step greatly simplifies the fabrication of the fibrous material and ensures efficient control of the fabrication steps.

The invention is explained in more detail below by means of some examples.

Example 1

To make the board, a fiber suspension containing bleached sulfite cellulose at a concentration of $ 5 and a Schopper-Riegler grinding degree of 90 ° was heated with steam at 142 ° C and 405 k Pa in an equilibrium state of the fiber suspension and the steam moisture in the equilibrium chamber.

The heated fiber suspension was fed to the steam in the shaping chamber, and the steam pressure was suddenly reduced from 405 k Pa to 101 k Pa, causing the fiber suspension to decompose in the steam air medium to form an air-material mixture with the fibers evenly distributed. The fibers are then subjected to descend the moving muotoiluseulalle bleached sulphite cellulose-containing vapor-air mixture 9 k Pa to a pressure difference effect which was achieved between the upper and the lower side moving screen. The shaped moist paperboard web was then dried by contacting it with a heated surface. The physical and mechanical properties of the produced board were as follows! basis weight 240 g, breaking length 5500 m, density 0.65 g / cm 2.

Example 2

To make the paperboard, a fiber suspension of waste paper with a fiber concentration of $ 10 and a Schopper-Riegler grinding degree of 0 to 45 ° was heated with steam at 12 ° C and 202 k Pa to achieve a closed fiber suspension between the heating chamber and steam. wet balance. The heated fiber suspension was fed as a stream to a shaping chamber where the vapor pressure was suddenly reduced from 202 k Pa to 101 k Pa. The following steps were performed in the same manner as in Example 1. The physical and mechanical properties of the prepared paperboard were as follows! basis weight 170 g, breaking length 2150 m, density 0.50 g / cm 2.

Example 5 To prepare a cover paper, a brown wood pulp fiber suspension with a fiber concentration of $ 16 and a Schopper-Rieger milling degree of 65 ° was heated with steam at 150 ° C and 262 k Pa to achieve a fiber suspension in a closed chamber. moisture balance between steam. The heated fiber suspension was fed as a stream to the shaping chamber and the vapor pressure was suddenly reduced from 282 k Pa to 101 k Pa. The following steps were the same as in Example 1. The physical and mechanical properties of the prepared coating paper were 70 g / m2, breaking length 3000 m, density 0.48 g / cm 2.

Example 4

To make the paperboard, a fiber suspension of bleached sulfite cellulose having a fiber concentration of $ 30 and a Schopper-Rieger milling degree of 90 ° was heated with heat at 142 ° C and 405 k Pa to achieve a moisture suspension between the fiber suspension and steam in the closed chamber. The heated fiber suspension was fed as a stream to the shaping chamber and the vapor pressure was suddenly reduced from 405 k Pa to 101 k Pa. The following steps were the same as in Example 1. The physical and mechanical properties of the prepared board were as follows: basis weight 230 g, breaking length 2800 m, density 0.65 g / cm 2.

The examples described above for the production of web-like fibrous materials from different raw materials show that the tensile strength of the finished product is high enough that the production can take place at a speed of more than 100 m / min. In addition, the use of expensive binders in the production of such a strong fibrous material can be dispensed with, which considerably reduces the manufacturing costs of the finished product.

The use of different wood fibers as a starting material significantly expands the field of finished products.