FI61216C - FOERFARANDE OCH ANORDNING FOER FRAMSTAELLNING AV CELLULOSAFIBRER AV ETT CELLULOSAHALTIGT HALVFABRIKAT - Google Patents

Description

RSr ^ 1 [B] (H) RELEASE 61216

I lJ '' UTLAGGNINGSSKRIFT

C Patent granted on 10 06 1932 • (45) Patent oeddelat ^ ^ (51) Kv, ik? /Int.ci.3 D 21 D 1/38 FINLAND —FINLAND (21) P »fnttlh» k «mo« - PifnowCkntnt 770817 (22) H * k «mlipUv (- AiwMcnlngadag 15 · 03.77 (23) AlkupUvft — Glklfhatadag 15.03.77 (41) Tullut julklMlul - Bllvit offwttllg

PaMnttl- i »rakiiMrihallltu · MNkWM.DU.p.-

Patent and insurance agency Amöfcan Utl «| d och utl.akrlftan publlcrad 26.02.82 (32) (33) (31) Claimed privilege * —Iffirm priority (71) Prospect Shvernika, Leningrad, USSR (SU) (72) Ivan Elizarovich Vyachov, Leningrad, Alexandr Ivanovich Glazunov, Lenin-gr ^ i, Vladimir Borisovich Nabilkov, Leningrad, Vitaly Alexandrovich Popov, Vsevolozhsk, Leningrad Oblast, Potash Timofeevich Dakhno, Kondrovo, Kaluzhskoi oblast,

Vladimir Alexeevich Chuikov, Kondrovo, Käluzhskoi oblast, Sergei Nikolaevich Titov, Petrozavodsk, Anatoly Etaitrievich Zotov, USSR (SU) (7M Oy Kolster Ab (5H) Method and apparatus for preparing cellulose fibers The present invention relates to a process for the production of cellulosic fibers from a cellulosic semi-finished product and to an apparatus for carrying out this process.

Cellulose fibers are essential for the pulp and paper industry and can be used effectively for the manufacture of hygiene and household items as well as for dry webbing.

According to the known method, in order to produce cellulose as separate fibers, a bale of cellulose-containing semi-finished sheets is fed to a feeder, which ensures a continuous feeding of the sheets to a refiner, where the sheets are crushed into semi-finished pieces of different sizes. The ground semi-finished product is then fed to a collection tank, from where it is transferred to plate grinders. In plate grinders, the semi-finished pieces are defibered by hard-faced grinding plates, which results in shredding of the fibers and, in addition, the formation of a considerable amount (up to 10 ... 15%) of dense lumps, so-called "branches". The cellulose thus produced as separate fibers is transferred by a pneumatic conveyor to a machine for the production of hygiene products.

The main weakness of this method is the uneven defibering of the cellulosic semi-finished product and, consequently, the poor quality of the pulp produced as separate fibers due to the numerous "branches" and untreated semi-finished ingredients and the considerable shortening of the fibers during defibering.

The above drawbacks lead to a deterioration in the absorption capacity of the cellulose produced as separate fibers and, consequently, to its higher consumption in hygienic articles.

Previously, a method for defibering a cellulosic pulp has been known, which involves feeding the cellulosic pulp to high-speed air jets, collecting and discharging it with the air stream generated by these jets, defibering by the vortices in this air stream and subsequently separating individual cellulose fibers from the inert species.

The apparatus required to carry out the known method comprises a loading pocket through which the cellulosic pulp is fed to a device for defibering in air jets, said device comprising spray nozzles and a ring tube for pulp transfer and defibering and fiber sorting

This method allows the pulp to be defibered without shortening the fibers and reduces the number of "branches" in it, but does not include pretreatment of the pulp before it is defibered. This disadvantage of the known method results in the uneven defibering of the cellulosic pulp and therefore in the poor quality of the cellulose produced as separate fibers, due to the large amount of untreated material particles in it, which degrades the quality of the products made therefrom.

The apparatus for carrying out the method described above does not have a device for preparing the cellulosic pulp for defibering. In addition to the homogeneous product, the fibers produced in this apparatus contain untreated particles.

It is an object of the present invention to obviate the above-mentioned drawbacks.

The main object of the present invention is a method for producing cellulosic fibers from a cellulosic semi-finished product, in which the semi-finished product is wetted and subsequently defibered into individual fibers to ensure homogeneous cellulose production as separate fibers; homogeneous defibering of the semi-finished product.

The above object is achieved by a method for producing cellulosic fibers from a cellulosic semi-finished product in the form of a web, wherein the moving web formed by the semi-finished product is then moistened and defibered by air jets. According to the invention, the wetting of the semi-finished product takes place by means of steam jets forming an air / steam zone in which the wetted area of the semi-finished product lingers for a short time so that the moisture particles

In addition, the semi-finished product should be moistened so that its moisture distribution between the fibers is 15 ... 60%.

Such a method is implemented with an apparatus for producing cellulosic fibers from a cellulosic semi-finished product, the apparatus comprising means for transferring and feeding the cellulosic semi-finished product to a humidifier, and then means for dispersing the moistened semi-finished product, including a support surface, a grinding drum to separate the wetted semi-finished product in an air jet into individual fibers which are removed to a tank for further use. According to the invention, this device is characterized in that the humidifying device has at least one pair of spray nozzles individually arranged on both sides of the semi-finished product to conduct moisture between the fibers evenly over the entire surface of the product to reduce inter-fiber cohesion, and the defibering means is provided with a feed roller arranged parallel to the shaft on the comb-like support surface, and the toothed disc elements of the grinding drum have a larger and smaller diameter and are positioned relative to each other such that the smaller-diameter element is alternately interposed between the at least one larger-diameter element, and the toothed disc members are interposed between the toothed disc members. projections of the comb-like support surface, which arrangement of the toothed disc elements, the feed roller and the comb projections allows the cellulosic web to be broken into substantially the same size into talemic particles.

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It is recommended that the holding surface of the feed roll consist of a series of plates fixedly mounted on a common shaft, each plate gripping a corresponding groove between the toothed disc elements, and the protrusions of the base surface concavely curved in contact with the plates.

The following is essential to the proposed invention:

Before defibering the cellulosic semi-finished product in very fast air jets, the semi-finished product is pre-wetted for a short time with steam jets evenly distributed over its entire surface. Under the influence of the dynamic pressure of the jet, the moisture particles in the steam jet penetrate between the fibers and wet the semi-finished product evenly over its entire thickness. The wetting method used allows the semi-finished product to be wetted to a desired moisture content of 15 to 60% distributed between the fibers. Wetting the semi-finished product to said inter-fiber moisture content considerably weakens the fiber bonds, resulting in homogeneous and efficient flotation of the semi-finished product into flakes and subsequent defibering in air jets. The short exposure time to moisture prevents the fibers from swelling during the wetting phase. The extent of wetting is determined by the quality of the semi-finished product and its further processing requirements.

The wetted semi-finished product is further ground into a flake-like state so that the flaky particles of the semi-finished product form substantially the same size.

The pre-wetted and uniformly ground semi-finished product is then fed directly into air jets where it is defibered and dried simultaneously. The supply of moisture in the wetting step only from the surface of the fibers of the semi-finished product ensures rapid drying of the fibers in the air jets during the defibering step.

Thus, the invention takes advantage of the characteristics associated with the actual defibering in air jets as well as the properties of the material to be treated.

Examination of the homogeneity of cellulose produced as individual fibers has shown that the presented method is very effective.

In order to implement the presented method, the invention also relates to the hardware construction used.

According to the invention, the apparatus includes a mechanism for transferring and feeding the cellulosic semi-finished product, a device for wetting it, a device for grinding the wetted semi-finished product and a device for defibering it in air jets.

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The transfer and feeding mechanism of the cellulosic semi-finished product ensures a continuous supply of the semi-finished product to the humidifier at a constant speed, and it also comprises a conveyor with a drive. The moistening device is provided with at least one pair on either side of the disposed spray nozzles. The shower nozzles are mounted so that the steam flow from them is directed to the vertical surface of the semi-finished product, which as a mixture of water and steam ensures even wetting of the entire surface of the semi-finished product.

The wetted semi-finished product refining device includes a support table having a comb-shaped surface, a feed roller and a refining drum so arranged and positioned that said device ensures that the wetted semi-finished product is ground into substantially flaky particles of substantially the same size.

The defibering device of the semi-finished product comprises a ring space provided with nozzles, and in the air jets of these nozzles the semi-finished product is defibered.

The method presented above enables efficient defibering of the cellulosic semi-finished product, whereby the individual fibers are very homogeneous and of high quality, and the construction of the equipment for carrying out this method is simple and reliable, which ensures the technological conditions for carrying out the manufacturing process.

The following is a detailed description of a hardware-specific embodiment with reference to the accompanying drawings:

Figure 1 is an overview of the equipment;

Figure 2 is a plan view of the apparatus shown;

Figure 3 is a plan view of the comb drum comb and teeth.

The apparatus shown in the drawings (Figures 1 and 2) includes: a feed conveyor 1 with a hold-down roll 2, steam nozzles 3 mounted downstream of this roll, a comb 4 with a main tooth 3 and an intermediate tooth 6 (Figure 3), a feed roller 7 and a grinding drum Θ on which large-diameter toothed end mills ^ and small-diameter milling cutters 10 are fixedly mounted between them. The radius of the small-diameter milling cutters is smaller than the radius of the large-diameter milling cutters according to the depth of the recesses of the comb 4. The plates 11 are mounted evenly on the shaft of the feed roller 7. The teeth of the large cutters 9 are placed between the teeth of the comb 4 and between the plates 11 of the feed roller 7. The surface of the tip of the intermediate teeth 6 of the comb next to the main teeth 5 and the roll 7 is curved, whereby the radius of the arc is larger than the radius of the roll 11 according to the web thickness of the semi-finished product (web).

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Beneath the refiner drum 8 is a device for defibering a cellulosic semi-finished product comprising a loading pocket 12, head air nozzles 13, a refiner chamber 14, a sorting zone 15, a return zone 16 and a branch tube for removing the separated cellulosic fibers.

The apparatus operates as follows: By means of the conveyor 1 and the retaining roller 2, the semi-finished web is permanently fed at a constant speed to moisten the steam jets discharged from the nozzles 3, after which the moistened semi-finished product passes under a feed roller 7 which grips it and conveys it. The grinding of the semi-finished product in the apparatus takes place as a continuous operation as follows: first with the teeth of large diameter milling cutters 9 on the intermediate teeth 6, then 10 for further grinding.

The pre-wetted and homogeneously ground semi-finished product is then fed through a loading pocket 12 into very fast air jets discharged from the nozzles 13. The air stream formed by these jets adheres to the semi-finished flakes and transports them to the heating chamber 14, whereby they are defibered by turbulent pulsations in the air stream. The resulting material particle envelope passes through the air into the curved sorting zone 15, whereby due to centrifugal force the large particles of the semi-finished product move to the outer wall of the sorting zone and return through the return zone 16 to the refining space 14 for re-defibering. The lighter particles, which are the individual fibers of the semi-finished product, pass from the sorting zone through the branch pipe 17 with the outgoing air flow. The cellulose thus produced as separate fibers is further separated from the air and directed to use in the manufacture of hygienic products, dry web and the like.

The apparatus shown in Figures 1 and 2 can be used for the production of cellulose as separate fibers from both the cellulosic semi-finished product as separate sheets and from a continuous web.

Examples of the use of this method for the production of cellulose as separate fibers from different cellulose species are given below. Example 1

The example considers the application of this method to the production of cellulose as separate fibers from bleached sulphite tea sheets made from air-dried softwood.

The cellulose is pre-moistened until the moisture content between the fibers 7 61216 is 30 io and ground »until flake-like cellulose particles of substantially the same size are formed. The pre-moistened and homogeneously ground cellulose is then fed directly to air jets to defiber it.

Moisture content of cellulosic fibers after defibering 12 It is known that the main requirements for cellulose as a separate fiber used in the manufacture of hygienic articles are high absorbency, as few "branches" and unextracted cellulose particles as possible, and as little shortening of cellulose fibers as possible.

The absorbency of cellulose as discrete fibers is measured by the method used to determine the absorbency of chemically purified hygroscopic cotton wool. The fiber composition is determined by the method used to determine the fiber composition of the groundwood.

The number of "twigs" and untreated cellulose particles is determined as impurities on a sieve with a hole diameter of 3 mm. Qualitative indicators of the bleached sulphite sieve are shown in Table 1.

Table 1 *? 2iil £ 25E2® * M2j $ LM Branches and Absorbency, water

Cellulose 'The number of fibers in innumerable gr. none 21.57

Original pulp sheet 91.3 4.6 1.2 2.9

Example 2

This method is applied, for example, to the production of cellulose as separate fibers from air-dried unbleached sulphite pulp sheets.

Prior to treatment, the pulp is moistened to 43% moisture between the fibers. The post-processing conditions and quality analysis methods for cellulose produced as separate fibers are the same as in Example 1. The qualitative indicators of unbleached sulfite pulp g 61216 are shown in Table 2.

Table 2 ----— - - —----. - _ * .---------- 'Fibers and Absorbency, \ J Cellulose posi-pt ^ treated- in grams of water' Number of fibers in the towers <£ /./ 84 4- _ cellulose, I II III IV $> & According to this method, the fiber habit 93.9 4.0 0.5 1.6 none 23.62

Original pulp sheet 94.0 3.9 0.6 1.5

Example 3

This method is applied, for example, to the production of cellulose as separate fibers from air-dried unbleached sulphite pulp sheets.

Prior to treatment, the pulp is pre-wetted for a $ 40 fiber-to-fiber test. The further processing conditions and quality analysis methods for cellulose produced as individual fibers are the same as in Example 1. The qualitative indicators for unbleached natural pulp are shown in Table 3.

Table 3 'Fiber Composites and Absorb- n .. 1 Cation,% Capacity, 8 u 008' Number of fibers luk55 * ίΡ5552ί55__ Count of particles 7 Number ύ Cellulose, I II III IV »r gr Fibered by this method - na 93.4 4.5 1.2 0.9 none 23.36

Original pulp sheet 93.2 4.6 1.2 1.0, 61216

The data from Examples 1-5 show that the homogeneity of cellulose produced as separate fibers according to this method is high because it does not contain "branches" or untreated cellulose particles. In terms of fiber composition, it does not differ from the original sheet cellulose, indicating that there is no shortening of the fibers in the defibering. As can be seen from the examples, said advantages of cellulose produced as separate fibers guarantee its better absorption capacity and thus its successful use in the manufacture of hygienic articles. In addition, the large length of the fibers allows the efficient use of the cellulose produced in dry web manufacturing processes. (processes of dry web forming) According to this method, the high absorption capacity of cellulose produced as separate fibers makes it possible to reduce its amount in hygienic products, whereby the amount of cellulose can be reduced by 15-25 # and thus achieve the economic result of industrial application of this method.

Claims (4)

A process for producing cellulose fibers from a cellulose-containing semi-finished product in the form of a web, wherein the moving web of the semi-finished product is wetted and then defibrated by means of air jets, characterized in that the semi-finished product is wetted by forming an air / vapor zone. by means of meadow jets, in which zone the wetted area of the semi-finished product is delayed for a short time so that the moisture particles of the meadow jets penetrate between the fibers, whereby the semi-finished product removed from the air / meadow zone until the flake-like particles of the semi-finished product the same size after which these particles are defibrated. Process according to claim 1, characterized in that the amount of moisture distributed in the space between the fibers in the semi-finished product is from 15 to 60%. Apparatus for carrying out the method according to claim 1 comprising means (1, 2) for moving and feeding the cellulosic semi-finished product into a wetting apparatus (3), and then placing means for defibrating the moistened semi-finished product comprising a support surface, a grinding drum (8) red-toothed disc elements (9, 10) and means placed after the drum for separating the wetted semi-finished product into air jets for individual fibers which are removed to a container for later use, characterized in that the wetting apparatus f3) has at least one a pair of spray nozzles placed individually on each side of the semi-finished product for applying moisture into the gap between the fibers uniformly throughout the surface to reduce cohesion between the fibers and the defibrillation medium is provided with a feed roller (7) arranged parallel to the shaft of the grinding drum (8) over the cam-like support surface (4) and of the grinding drum's toothed disc elements have other larger and second smaller diameters and they are positioned relative to each other such that a smaller diameter element is placed alternately at least between a larger diameter element, and in the danger between the toothed disc elements (9, 10) the pouring surface of the feed roller ( 7) and the protrusions on the cam-like support surface, which arrangement of the toothed disc elements, the feed roller and the caraway protector allows the cellulose web to be defibrated into substantially equal Large flake-like particles. 4. Apparatus according to claim 3, characterized in that the pouring surface of the feeder roller (7) is formed by a disk series (11) which is movably mounted on a common shaft, each disk being engaged with