DK170259B1 - Plant and method for producing a toroidal fiber product - Google Patents

Description

in DK 170259 B1

The present invention relates to a plant for producing a dry-formed fiber product comprising A) a plurality of fiber distributors, each having a substantially planar bottom and arranged immediately after each other and arranged for depositing each layer substantially simultaneously on one and the same molding wire, B) an endless molding wire which can be fed in a web located under the bottom of the fiber distributors, and C) a suction device arranged throughout the molding wire.

Plants of the type described above for dry forming are known, inter alia, from Krøyer US Patent Nos. 4,014,635 and 4,494,278 as well as the Danish Krøyer Nos. 153,530 and 162,845 and European Patent Publication No. 0.006,696.

In the prior art plants for the production of dry-formed fiber products, there is a limited capacity which depends on how quickly the fibers are deposited on the forming wire in such an amount that they are connected to each other. Therefore, it is often necessary to operate at a relatively low feed rate for the forming wire, thereby limiting the capacity by which the fiber products are manufactured. The plants known from the aforementioned writings are particularly suitable for the manufacture of thin one-layer fiber products, that is, one-layer fiber products with a weight weight of down to 30 - 150 g / m2. The fiber products thus formed will have similar properties throughout the thickness. By dry forming technique known from the above-mentioned writings, it is known to place a number of fiber distributors above the molding wire to increase the production capacity by forming thicker layers. However, the products formed will still be continuous one-layer fiber products.

In wet forming, products with a weight down to 11-20 g / mz can be produced. Such a low weight is necessary to get a soft product in the wet forming process. Such products are widely used as kleenex-type products as well as toilet paper, which will usually be made by folding in a special folding station. As merging occurs, the actual fabrication rate of the wet forming plant will be reduced to one-half or one-third, depending on whether two or three layers are merged.

From wet forming technique, it is known to produce one-layer fiber products on separate molding wires and then route several of these separate 2-layer fiber products to a merging station. However, the use of a merging station is expensive. It is possible to impart different properties to the different wet-shaped layers, but it is often very difficult to make the layers adhere together to form a homogeneous product. Furthermore, it is necessary that the wet-shaped fiber layer has a certain weight of weight so that it does not break during removal from the molding wire. Even the known wet forming machines make it practically impossible to form multi-layered products where the individual layers have a weight of less than 10 - 12 g / m2. Due to the wet forming, hydrogen bonds inevitably form which make the product stiffer. There are necessarily many hydrogen bonds, since very large quantities of water are used to distribute the fibers. It is therefore necessary, by wet forming technique, to form the so-called soft products of low layers of low weight by later merging into an expensive merging station.

It is the object of the present invention to overcome the disadvantages of the known wet forming plants and to provide a dry forming plant suitable for the manufacture of multilayered fiber products where the individual layers can be made with a low gram weight and with desired properties and where possible determine the degree of integration between the individual layers that determines whether the finished product should appear as one product and so that the product essentially acts as a one-layer product without the risk of partial amination.

This is achieved according to the present invention with a plant of the type mentioned in the beginning, which is characterized in that an adjustable wetting unit and an adjustable compression unit are arranged immediately after each fiber distributor, seen in the direction of the feed wire.

The system according to the invention is suitable for making all types of paper items such as napkins, sheets, tablecloths, photocopying paper, filter media and hygiene products such as sanitary napkins, panty liners and the like. Thus, it is possible to supply each of the fiber distributors from its own defibrator / hammer mill. This makes it possible to use different types of fibers for the different layers of the product. Furthermore, it becomes possible to mix various components, such as bi-component fibers in any layer, but preferably in outer layers and superabsorbents in a middle layer in three-layer products.

3 DK 170259 B1

Thus, the fiber products produced at the plant according to the invention are not just so-called "soft" products, such as napkins, toilet paper and the like. These are all types of paper including ordinary and thick paper products, such as thick packaging paper, photocopying paper, corrugated paper and the like. In dry forming according to the present invention, soft products can be formed with a greater gram weight, since only controllable and possibly very few hydrogen bonds are present. Since the number of hydrogen bonds can be regulated via setting of the wetting unit, it is also possible to produce on the plant according to the invention ordinary paper products such as copy paper.

In the plant, it is possible to humidify and compress the formed fiber layers in a controlled and controlled manner, thereby controlling and controlling the degree of hydrogen bonds. The wetting is in the form of finely atomized water droplets applied by the wetting unit located directly above the product. The wetting unit has a downward opening, thus avoiding the risk of wetting the subsequent compaction unit which perceives two cooperating compression rollers. This controls and controls the softness of the product (hand and feel). At the same time, the degree of integration between the layers can be controlled and controlled.

In the system of the present invention, all layers are dried on a single molding wire. Laying of the layers takes place almost simultaneously. In practice, the deposition of a subsequent layer occurs less than a second after the formation of a previous layer. Since immediately after each fiber distributor, seen in the direction of the shape of the feed, it is possible to variably humidify and compress the formed fiber layer, it is possible to form a further increased fiber product where a greater or lesser degree of integration between the individual layers can be achieved. so that the product can act as a one-layer product without the risk of delamination or as a multi-layer product with separation between the various layers.

Thus, depending on the desired properties of the resulting fibrous fiber product, a greater or lesser amount of water can be supplied. This creates the possibility of hydrogen bonds between the fibers. It is also possible to make a larger or smaller heating by means of the compaction unit, which also has the option of adjusting the pressure exerted to compress each of the formed fiber layers. Thus, with the plant, it is possible to produce a layered product, in which different forms of layering occur and thus also different degrees of integration between the individual layers of the product.

Since it is possible to obtain different degrees of layering, it will be possible to contain additives, for example superabsorbents, which are placed in an intermediate layer with a higher gram weight, for example up to approx. 100 - 200 g / m2 between outer layers made of lower gram weight. In such a product, at least one of the outer layers, in a manner known per se, may be formed of fibers blended with bi-component fibers, so as to obtain a strong but flexible outer layer which, however, allows easy and rapid passage of body secretions. into an intermediate absorbent layer. Thus, the outer layers can be made of hydrophobic fibers with flow openings formed to allow body fluids to penetrate at least one outer layer. Thus, the middle layer containing superabsorbents may be made of hydrophilic fibers.

Since all the layers are formed on one and the same mold wire, the use of an expensive joining station is avoided and it will be easy to control the process in such a way that the fibers in the interfaces between the different layers are compressed but with certain fibers protruding from it. compressed surface. Thus, it will be possible to form bonds between fibers from different layers. Thus, it can be said that the layers are integrated with or "grown" into one another in a way that they are sufficiently interconnected to avoid partial amination.

Thus, a further increased product manufactured on a plant according to the invention, after being removed from the molding wire, can be passed through embossed roll pairs to form ready-to-use hygiene products which are well-known in themselves. binder application as well as cure is made with an edge adhesive so that the products are ready for use after cutting the formed square fiber web.

The plant will be able to operate at a high speed for the forming wire, for example, production rates can be used for the finished product, which is significantly greater than production rates on nuclear plants at the simultaneous decommissioning of three fiber distributors. The mold wire 5 DK 170259 B1 is conveyed at a rate which, depending on the gram weight of the product and the fiber dosing capacity of the plant, will typically be between 100 and 600 m / min, preferably between 200 and 400 m / min. This is impossible with known plants, whether wet or dry forming. At the same time, different fiber grades can be used in the different layers of the product. Since each subsequent layer is deposited on a fiber layer after less than a second on a layer that is more or less compressed, it will be easier to place on the wire than if each layer was deposited on separate bronze wires.

Since a subsequent layer is closed down almost simultaneously with a previous layer, there is no risk of beach width effect. Thus, with a plant according to the invention, it is possible to double or triple the plant's production capacity. This is a very significant technical advance, as known dry forming plants, compared to known wet forming plants, have had the disadvantage that the production rate has been only a fraction of the production rate of a wet forming plant.

The invention also relates to a method of producing a web-shaped fiber product on a plant comprising A) a plurality of fiber distributors, each having a substantially planar bottom and arranged immediately after each other and arranged to deposit substantially each layer simultaneously on one and the same forming wire, B) an endless forming wire which can be fed in a web located under the fiber distributors, and a C) suction device placed under the forming wire opposite the fiber distributors.

The method is characterized in that each fiber layer is immediately moistened and compressed immediately after placement on the forming wire before any additional fiber layer is formed thereon.

In the process, it is possible to significantly increase the production capacity of a dry forming plant.

The method according to the invention is carried out by introducing defibrated fiber material from one or more defibrators, for example hammer mills, into the fiber distributors and therein, under the action of stirring means, a movement is made over the fiber-bottomed bottom of the fiber distributor. One row of wings is preferably used.

6 DK 170259 B1

Stirring means which are arranged in rows transverse to the feed direction of the molding can also be used, which are described in, inter alia, Krøyer US Patent No. 4,494,278. The stirrups in each row may have partially overlapping regions of action. There will thus be formed endless sausage-shaped bodies of loosely coherent fibers which move across the direction of movement of the forming wire across the bottom, and which during this movement emit single fibers which, after passing through the bottom under the action of the suction from the suction device below the forming wire, is deposited on the forming wire or on the pre-formed fiber layer on the forming wire.

In each of the fiber distributors subsequently used, problems with the release of short and ultra-short fibers are reduced, as the pre-formed layers of the forming wire will act as a filter retaining these short fibers in the formed fiber product.

The invention will then be explained in more detail with reference to the accompanying schematic drawing, in which fig. 1 is a partial side elevational view of one embodiment of a plant according to the invention; FIG. 2 is a partial sectional view of the left-hand side of FIG. 1 shows an embodiment of a plant according to the invention, and FIG. 3 shows an enlarged fragmentary sectional view through part of the embodiment of FIG. 1 and 2.

In FIG. 1 shows a plant according to the invention comprising three identical fiber distributors 1. The fiber distributors 1 are arranged in a row over an endless forming wire 2. Each fiber distributor 1 has a flat bottom in the form of a net 3 which is immediately above the forming wire 2. The net 3 in the different fiber distributors 1 may have different mesh sizes. Thus, for some products it may be advantageous for the middle fiber distributor 1 to have a mesh 3 with smaller openings than the other two to allow only the passage of short fibers in an intermediate layer in the finished% product. The mold wire 2 is advanced in the direction of an arrow 4. The finished fiber product 25 is passed through a heating / embossing station 26.

7 DK 170259 B1

A suction box 5 with suction openings 6 is arranged under the forming wire under the fiber distributors 1. Alternatively, several suction boxes 5 arranged under each fiber distributor 1 can also be used. Hereby it is possible to vary the vacuum under each of the fiber distributors 1. This can be an advantage , for example, to obtain sufficient suction power at the last fiber distributor 1.

The housing 7 of each fiber distributor 1 is connected via a pipe 8 to a defibrator (not shown) for supply of dry defibrated fiber material. Within the housing 7, the applied fibers are evenly distributed over the entire area using known baffle plate system (not shown). Each fiber distributor 1 further comprises a plurality of stirring members 10, each comprising a stirring vane 11 and a vertical shaft 12. The shafts 12 are connected via drive wheels 9 and drive belts 23 to drive means in the form of an electric motor 24 (see fig.

2). Each pipe wing has a diameter of 800 - 1000 mm, and the five pipe wings 11 shown thus cover a web width of 3.0 - 3.2 m and will be spaced with a mutual wheelbase of 450 - 600 mm. The embodiment shown is a so-called compact unit in which a number of stirring means 10 are used.

However, it is also possible to use a different number of rows, for example 4, 8 or 12, if commonly known fiber distributors are used, for example as described in part of the above-mentioned patents.

Immediately after each fiber distributor 1, as seen in the feeding direction 4 of the forming wire 2, a variable adjustable wetting unit 13 and a variable adjustable compaction unit 14 are arranged.

The wetting unit 13, seen most clearly in FIG. 3, is constituted by a water spray lance 19 having a downwardly directed slot 20 located close above the surface 21 of the formed fiber layer 22 and emitting finely atomized water droplets. These fine water droplets are emitted via the downwardly directed slot 20. Since the lance 19 is placed close to the surface 21 of the fiber layer 22, there is no risk of the water hitting the compaction unit 13. The water drops are sucked down into the fiber layer by means of the suction box 5 located below forming wire. The lance 19 is connected via a conduit 15 to a fluid supply (not shown). The capacity of the wetting unit 13 is adjustable so that it can deliver an amount of water equal to 0 - 50% of the amount of fiber deposited by the immediately located fiber distributor 1. This adjustment of the capacity can be done manually or automatically by control means connected to the fiber distributor 1.

<

Each compaction unit 14 comprises two compression selections 16,17. At least the roller 17 is provided with heating means (not shown) which can be adjusted for heating the roller to a temperature between 50 and 200 ° C or higher. The two compression rollers 16,17 are interconnected by adjustable clamping means (not shown), for example in the form of hydraulic cylinders. Hereby, the degree of compression can be set for a fiber layer 22 formed by an immediately preceding fiber distributor 1.

As explained earlier, with identical fiber distributors, it becomes possible to achieve different degrees of integration between the individual layers by:. vary the water supply from the wetting unit as well as by adjusting the temperature and compressive strength of the compaction unit.

The FIG. 1 can be used to make a three layer fiber product in the form of a sanitary product, for example a sanitary napkin. The first fiber distributor is provided with hydrophobic fibers to form a thin outer layer in the sanitary product. For example, this outer layer may have a weight of between 10 and 200 g / m2. In the middle fiber distributor 1, hydrophilic fibers may be supplied, for example containing superabsorbents. The layer formed by the middle fiber distributor is deposited on top of the pre-formed and compressed layer. The hydrophilic fibers can be deposited in a layer weighing up to 100 - 200 g / m2 including superabsorbents. In the last fiber distributor 1, a layer of hydrophobic fibers corresponding to the layer formed by the first fiber distributor can be formed.

In the two outer layers, bi-component fibers can be used to obtain the greatest possible strength in these layers when the finished sanitary product subsequently undergoes a well-known cure in itself.

The superabsorbents present in the hydrophilic fibers of the intermediate layer will be enclosed in the middle layer and there will be no risk of the powdered superabsorbents falling out before use. Due to the bonds formed in the boundaries of the different layers, the superabsorbents will remain in the middle layer. Alternatively, the superabsorbents may also be provided in several of the layers formed or in interfaces between the layers.

In FIG. 2 is a plan view of the plant shown in FIG. 1. Thus, a compact unit has been used as the fiber distributor 1. The plant is shown with a defibrator 18 which is not placed adjacent to the housing 7. The fiber 7 of the housing 1 is thus supplied with fiber material via the pipes 8. This fiber material is evenly distributed. all over the housing 7 by means of a baffle plate system (not shown). In this embodiment, the defibrators / hammer mills 18 will be housed in a separate room so that noise problems are reduced in the vicinity of the dry mold itself in the plant.

In the illustrated embodiments, it is possible to produce a dry shaped multi-fiber product without the need for collation stations. Thus, the multilayered fiber product can be made with the desired thickness and type of individual layers in a relatively uncomplicated manner and at a lower cost than is the case when using merging stations. Furthermore, the invention makes it possible in a simple way to vary the degree of infiltration or coherence that occurs between the different layers of the product. Thus, different properties can be established in different layers without the risk of partial amination of the finished product.

Although the figures are shown in the figures with three fiber distributors 1, within the present invention it will also be possible to use fewer or more fiber distributors, depending on how many layers are desired in the finished product.

Claims (10)

10 DK 170259 B1 PATENT REQUIREMENT. A plant for producing a dry-formed fiber product comprising A) a plurality of fiber distributors, each having a substantially flat bottom and arranged immediately after each other and arranged for depositing each layer substantially simultaneously on one and the same molding wire, B) an endless mold wire which can be fed in a web located below the bottom of the fiber distributors; and C) a suction device which is arranged throughout the preform, characterized in that immediately after each fiber distributor, seen in the direction of feed of the mold wire, a adjustable wetting unit as well as an adjustable compression unit. Installation according to claim 1, characterized in that the compression unit comprises roller pairs with adjustable heating means and controllable clamping means, and that the wetting unit is provided with adjustable water nozzles over the width of the formed web. System according to claim 1 or 2, characterized in that the fiber distributors are connected to each fiber supply. Plant according to any one of the preceding claims, characterized in that each fiber distributor is arranged to be able to deposit a fiber layer having a gram weight between 10 and 200 g / m2. System according to any one of the preceding claims, characterized in that each wetting unit is arranged to be capable of supplying a water quantity of 0 - 50%, preferably 10 - 25% of the fiber weight deposited by the immediately preceding fiber distribution is and that the compression unit is arranged to be heated to a temperature between 50 and 200 ° C. A method of manufacturing a web-shaped fiber product on a plant comprising A) a plurality of fiber distributors, each having a substantially planar bottom and disposed immediately after one another and arranged to deposit each layer substantially simultaneously on one and same, forming wire, B) an endless forming wire which can be fed into a web located under the fiber distributors, and C) a suction device placed under the forming wire opposite the fiber distributors, characterized in that each fiber layer is wetted immediately after placement on the forming wire and DK 170259 B1 π is compressed before any additional fiber layer is formed. Process according to claim 6, characterized in that a quantity of fiber is applied between 10 and 100 g / m 2 in each layer and a quantity of water between 0 and 50%, preferably 10 - 25% of the fiber weight in a layer is applied. Process according to claim 6 or 7, characterized in that the compression rollers are heated to a temperature between 50 and 200 ° C. Method according to any one of claims 6-8, characterized in that in one or more of the layers between the layers superabsorbents are used. Method according to any one of claims 6-9, characterized in that the forming wire is advanced at a speed between 200 and 400 m / min.