DK144426B - PROCEDURES AND PLANTS FOR MANUFACTURING PATHFORMED FIBER PRODUCTS - Google Patents

Description

(19) DENMARK

lp new PROGRESSION WRITING ου 1A4426B

DIRECTORATE OF THE PATENT AND TRADEMARKET SYSTEM

(21) Application No. ^ 127/78 (51) int.CI.3 D 21 H 5/26 (22) Submission date 18. seP · 1978 q µ 1/00 (24) Running day 18 sep. 1978 (41) Aim. available March 19 198Ο (44) Submitted Mar 8. 1982 (86) International Application No. - (86) International Filing Day - (85) Continuation Day - (62) Master Application No. - (30) Priority - (71) Applicant KARL KRISTIAN KOBS KRØYER, 1302 Copenhagen K, DK.

(72) Inventor Same.

(74) Associate Engineer Lehmann & Ree.

(54) Process and plant for the production of web-shaped fiber products.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of producing web-based fiber products in which an endless air-permeable molding belt is passed by a number of fiber distributors disposed at one side of the molding belt, from which fibers are released which towards the forming ribbon to form fiber layers thereon.

In the manufacture of web-shaped fiber products by a known method or method of the aforementioned kind, the fiber distributors are spaced <N along the endless, air-permeable molding belt and a J-suction box is provided for each fiber distributor.

In Danish Patent Application No. 4956/77, a method is described in which an endless air-permeable molding belt is passed under a fiber distributor consisting of a number of assembled fiber distributor units, which may be designed so that fiber material can move from a unit adjacent thereto, and under which is provided a suction box common to the assembled fiber distributor units, which ensures that the fiber layer, while increasing its thickness evenly, is continuously sucked against the belt.

The invention is based on the recognition that a method of the kind mentioned in the introduction can be obtained with a fiber product having at least one surface layer consisting predominantly of relatively long fibers and in which a middle layer consists predominantly of relatively short fibers.

A fiber product with such a structure is particularly soft and has a good grip and a relatively high strength, which is why it is particularly suitable for the production of relatively light fiber products, especially fiber products weighing less than 100 g / m. Such products are in particular used as so-called paper towels, including facial tissues, paper towels, toilet paper, etc.

Furthermore, the relatively high strength causes the fiber product directly, i.e. without an intermediate support belt, can be transferred from the molding belt to a drying cylinder.

The method according to the invention is characterized in that the air-permeable endless strip has openings with a luminous area greater than 1 mm and that fibrous material passing through the strip under a given fiber distributor is fed to one or more sequentially arranged fiber distributors in the conveying direction.

2

By using a molding tape having a brightness area greater than 1 mm, only the relatively long cellulose fibers delivered from the first in the series of fiber distributors will be retained by the molding tape, whereas the relatively short fibers will pass through the tape down into the suction box.

The relatively long fibers in the fibrous material passing through the molding surface under the first fiber distributor, when recycled to the following fiber distributor and from there sucked into the molding strip with the long fibers deposited thereon, will be deposited thereon while the short fibers again pass through the band. As the fiber layer builds, this becomes denser, and even relatively short fibers will eventually be deposited.

In the manufacture of web-shaped fiber products using multiple fiber distributors, each consisting of a number, e.g. 6, fiber distributor units, by supplying fiber material to each fiber distributor directly from one or more defibrators, a fiber product can be obtained in which both surface layers consist predominantly of relatively long fibers.

This is achieved by adding fiber material consisting of relatively short fibers originating from a prior fiber distributor to the rear portion of the last fiber distributor relative to the shape of the feed belt. Hereby, the relatively short fibers will relatively quickly pass through the bottom of the fiber distributor and be deposited on the already formed layer on the molding tape. However, the relatively long fibers will spread over the entire fiber distributor, including over its front portion. In this part, they will be subjected to a particularly strong influence on the agitators provided herein, since the other relatively short fibers have already left the fiber distributor. Under these circumstances, there is an increased likelihood that they will occupy such a position relative to the openings in the bottom of the fiber distributor that they can pass through it.

This causes a surface layer of relatively long fibers to form on the already formed fiber layer.

It should be noted that the term "distributor" herein is also to be understood as one of the distributor units included in one of several such composite fiber distributors. Using a fiber distributor composed of several such units, fiber material which has passed the mold surface under such a fiber distributor unit is passed to one or more of the following fiber distributor units, e.g. may be located within the same housing.

A further advantage of the described process is that the first applied fiber layer acts as a filter for later application of fiber and air mixture, thereby ensuring that very little fiber material is lost, which partly improves the production economy and partly that the pollution problems reduced to a minimum.

In the manufacture of fiber products which mainly consist of cellulose fibers, which are usually 0.5-3 mm in length, a molding tape is preferably used, the mesh dimensions of which in the cross machine direction are from 0.5 to 1.5 mm. These holes are preferably elongated in the machine direction, and the length of the holes in this direction, for example, is up to 3 times the width of the holes.

In the method, a woven metal mesh is conveniently used, where the warp and weft threads are placed in canvas binding. Preferably, a net is used where the distance between the shot wires is preferably greater than the distance between the warp threads, thereby providing a better opportunity for the net to be cleaned.

A particularly suitable metal mesh is a mesh in which the shoot threads are straight-line, while the warp threads break at the points of intersection. In such a network, the chain wires break points form the web surfaces, and the shot wires are withdrawn from the surfaces, which is why there is less risk of fibers accumulating at the junctions than in the commonly used metal mesh.

The molding band is, as mentioned, preferably a metal mesh. However, it can also be made from plastic threads and does not need to have the shape of a fabric. Thus, the tape may be formed of a perforated metal or plastic film.

In a preferred embodiment of the method according to the invention, several, e.g. 3, along the forming strip, fiber distributors, each consisting of several, e.g. 6, fiber distributor units, each comprising a series of transverse strips disposed on the strip.

The invention further relates to a plant for the production of web-shaped cellulose fiber products according to the present process, which comprises an endless air-permeable molding belt, a number of fiber distributors disposed along the molding belt on one side, or one or more co-operating suction boxes arranged with the fiber distributors on the other side of the molding belt. The plant according to the invention is characterized in that the molding belt has openings with a luminous area greater than 1 mm and that it has piping connecting the suction box or suction boxes under a given fiber distributor with one or more of the other fiber distributors arranged in the conveying direction of the conveyor.

The invention will now be described in more detail with reference to the drawing, in which fig. 1 is a sectional view of a preferred metal mesh for use in the method of the invention; FIG. 2 shows that in FIG. 1 illustrates meshes in perspective view; FIG. 3 shows a preferred embodiment of a plant according to the invention, and fig. 4 shows another embodiment of a plant according to the invention.

The FIG. 1 and FIG. 2, the metal nets shown in Fig. 2 consist of warp threads 1 and weft threads 2, the weft threads 2 being spaced at a greater distance than the warp threads 1. As a result, the openings 3 in the web are rectangular in shape. The warp yarns 1 and the yarns 2 are arranged in so-called canvas binding, however the yarns 2 are rectilinear and the warp yarns 1 break at the junction points with the yarns. The mesh shown is particularly easy to clean of adherent fibers, fiber clumps, binder, etc. when brushed by a brush that rotates about an axis parallel to the longitudinal direction of the shooting wires, as the shooting wires are not near the surface of the mesh.

The systems shown in FIG. 3 and FIG. 4, are in principle identical with regard to the molding and adhesive sections, and the same components of these sections of the systems are therefore designated by the same reference numerals.

5 144426

The mold section consists of three fiber distributors 10, 11 and 12 which are arranged one after the other over a molding strip 13, the direction of conveyance being shown by an arrow 14. Each fiber distributor consists of six fiber distributor units arranged in a common housing 15. Each fiber distributor unit comprises a number of agitators 16 arranged in a row across the conveying direction of the molding band 13. The agitators 16 have wings which cover an area above the bottom of the distributor housing, which has the shape of a side bottom. Between adjacent rows of agitators 16, partitions 17 are disposed. These partitions 17 do not reach all the way to the bottom of the housing 15, and thus a material movement may occur from one area under one row of agitators 16 to an adjacent area under another row of agitators 16. .

Fiber distributors of the kind mentioned above are known from e.g. the description of Danish patent application no. 4956/77.

Under each fiber distributor 10,11,12, a suction box 18, 19,20 is provided containing a series of support rollers 21 for the molding belt 13. The fiber distributors 10, 11 and 12 are connected to supply pipes 22,23 and 24 for freshly defibrated fiber material, respectively. Fiber material which has passed through the molding belt 13 under the first distributor is preferably fed to both the second and third fiber distributors, seen in the conveying direction of the belt 13, in order to obtain an appropriate air balance in the system of fiber distributors. In the embodiment shown, the suction box 18 is connected through a pipe 25 in which an air pump 26 is connected to the middle part of the fiber distributor 11 and the rear part of the fiber distributor 12. The freshly defibrated fiber material supply pipes also open in the rear part of the the fiber distributor 12.

The suction box 19 is connected to a suction pump 29 by means of a connecting pipe 27 and the suction box 20 by means of a connecting pipe 28. The transport of fiber material from the suction box 18 under the first distributor 10 to the second fiber distributor 11 and the third fiber distributor 12 is thus partly accomplished by means of a suction pump. of the air pump 26 and partly by the suction pump 29. The systems shown further comprise a spray booth 30 located in the immediate vicinity of the fiber distributors 12 and above the molding belt 13.

In the system shown in FIG. 3, the return line of the molding belt 13 is disposed under the fiber distributors 10, 11 and 12 and the spray booth 30, the molding belt being supported by the rollers 31-36, the rollers 31,32 being pressure rollers which serve to press the formed fiber web against a drying cylinder where the roller 34 is a guide roller and the roller 35 is a tension roller.

The FIG. 3 further comprises a rotatable drying cylinder 37, a doctor's knife 38 and rollers 39, 40, 41 and 42 for supporting a fiber web 43 formed in the system before being wound up in the form of a roller 44.

In the system shown in FIG. 4, the molding belt 13 is guided around a drying cylinder 45 and the return flow is supported by rollers 46-50, with the roller 47 being a guide roller.

The FIG. 4 also includes a doctor's knife 51 as well as rolls 52,53,54 for a fiber web 55 which, in wound form, forms a roll 56.

Above the molding belt 13 between the dryer roll 45 and the roller 52, a suction box 57 containing a series of support rollers 58 for the molding belt 13. A drying oven 59 and air ducts (not shown) are arranged on the opposite side of the molding belt 13.

When supplying freshly defibrated cellulose fiber material, optionally containing a smaller amount of synthetic fibers, e.g. thermoplastic plastic fibers, for the fiber distributors 10-12 and by suction of air by means of the suction pump 29, and the transport of air containing relatively short fibers from the suction box 18 to the fiber distributors 11 and 12, on the molding strip 13 included in the two plants, shown in FIG. 3 and FIG. 4, fiber layers are gradually built up, which consist mainly of relatively long fibers on the underside and the upper side. After the fiber layer formed in the fiber distributor 12 has reached the desired thickness, it passes through the spray booth 30.

In the manufacture of relatively thin fiber webs by known methods, one or more auxiliary tapes are used to transport the fiber web removed from the molding strip to a drying station.

By using the relatively open molding belt mentioned herein, it has now been found possible to insert the thin fiber web formed on the molding strip directly onto a drying cylinder. This significantly helps to make a plant for the production of web-shaped fiber products more compact and to reduce the construction, construction and operating costs of such a plant.

Furthermore, when the molding tape during the transfer of the fiber web to the dryer cylinder is pressed against the latter, e.g. by means of one or more pressure rollers, on both sides of the fiber web a surface pattern is formed which corresponds to the surface pattern of the belt. This results in that the fiber web will essentially only cling to the drying cylinder in a point or line pattern similar to the molding surface pattern.

This is of great importance in the later removal of the dried fiber web from the drying cylinder. Thus, until now only a thin fiber web has been able to be removed, which is bonded over the entire contact surface to a drying cylinder in connection with a creep of the fiber material. By using the method according to the invention, the fiber web can also be removed without simultaneously cramping.

The fibers in the finished fiber web are held together by a binder. Such a binder can be applied to the fiber material in various ways. Thus, a solid binder, e.g. modified starch, which is activated by the application of moisture, is introduced into the defibrillator, e.g. the hammer mill used to prepare the defibrated material supplied to the fiber distributors.

When applied to the fiber distributors together with the defibrated fiber material, the binder will substantially pass the mold surface under the first fiber distributor and will therefore be deposited primarily in the fiber layers above.

For example, to induce the aforementioned activation of the binder, it is sprayed. water while the fiber web is on the molding tape. Excess water is removed during the fiber web's contact with the drying cylinder. During the heating of the fiber web thus obtained, curing of the binder occurs.

In the illustrated embodiments of the apparatus of the invention, the fibrous web is sprayed onto a binder solution or suspension while the fibrous web is on the molding tape.

Using a thermosetting binder, it may be necessary to heat the fiber web more vigorously than that obtained by the fiber web's contact with the drying cylinder.

This can be achieved by passing the web from the drying cylinder after removing the fibrous web through a curing furnace in which hot air is passed through the fibrous web.

During this heating of the fiber web in order to obtain a cure of the thermosetting binder, it is desirable to keep the fiber web supported.

This can be achieved by using the return loop on the molding tape as a support for the fiber web during the curing process.

Further, the binder application may be effected by applying e.g. upon rolling, the surface of the molding tape has a binder solution or suspension of relatively high viscosity. The binder will thereby be deposited primarily in the projected areas of the belt (the points of intersection of a woven metal mesh) and will thereby be pressed into the fibrous web during the embossing which is induced as the molding strip with the fibrous web then pressed against the dryer cylinder.

In the system shown in FIG. 3, the fiber layer is contacted 8 with the drying cylinder 37, e.g. is heated to a temperature of 160 ° C, at the same time as it is strongly compressed.

The fiber layer is then released from the molding belt 13 and brought under the rotation of the drying cylinder 37 to contact the take-off knife 38. At this point, the binder is cured and a self-supporting fiber web 43 is obtained which is then wound in the form of a roll 44. Depending on the shape of the take-off knife 38, affixing, a fiber web removal is obtained in crepe or uncreped form. When a crepe is made, the length of the fiber web will usually be reduced by approx. 20%. As mentioned, due to the manner in which the fiber web is connected to the surface of the drying cylinder, the fiber layer can be removed from it without simultaneously making a creep. A fiber web can thus be obtained with a smooth surface and with substantially the same surface properties in all directions.

Along the return path of the molding belt 13 between rollers 32 and 36, a brush (not shown) is disposed to remove fiber or binder residue from the belt 13.

The necessary pressure to press the fiber web against the drying cylinder 37 may also be provided by the forming band being arranged in such a manner that it encloses a substantial portion, e.g. up to 180 ° C, from the periphery of the drying cylinder.

One such embodiment illustrated in FIG. 4 is particularly useful in the case where the return strip of the molding strip is located above the row of fiber distributors and where it is therefore possible to place the part of the molding strip on which the fibrous web is formed in floor plan.

Preferably, as an dryer cylinder, an internally heated drum is used. The surface of the drying cylinder is preferably heated to a temperature of 100-200 ° C and especially preferably 120-160 ° C.

The device according to FIG. 4, as mentioned, is brought into contact with the drying cylinder 45 by holding it compressed between it and the molding strip 13. During this contact, even using a thermosetting binder, sufficient curing takes place that the web-shaped fiber product after it is been removed from the drying cylinder 45 by the removal knife 51 is self-supporting.

After removal from the drying cylinder, the fiber web 55 is drawn up against the molding belt 13 under the action of the vacuum in the suction box 57.

During the passage over the suction box 57, hot air produced in the drying furnace 59 is sucked through the fiber web, thereby completely curing the binder. The fiber web 55 thus formed can then be wound in the form of a roll 56.

9 U4426

The return strip of the molding tape is cleaned in the same manner as discussed in connection with FIG. Third

The invention will be further illustrated by the following examples: EXAMPLE 1 In a hammer mill, cellulose pulp (type "Korsnasss Marma") and oxidized starch (type "Viscosol 220") were introduced in a ratio of 95% cellulose pulp and 5% oxidized starch. After forming a fiber web in a plant as shown in FIG. 3 and comprising a metal mesh with mesh openings with an area of 1.5 mm sprayed water containing 4% dissolved oxidized starch (type "Viscosol 220"). When measuring, it was found that when the fresh fiber product was fed in equal quantities to the three fiber distributors, approx. 20% of the total amount of starting material through the metal mesh under the first fiber distributor and transferred to the second and third fiber distributors. After transferring the fiber layer from the metal mesh to the drying cylinder having a temperature of 120 ° C, a product whose water content, before being removed from the drying cylinder by a crepe knife, was 25%. The product was rolled up with a length reduction of approx. 22%. The fiber product obtained had a weight of 2 30 g / m and was suitable for use in the manufacture of toilet paper and napkins.

EXAMPLE 2

A fiber product was prepared using the same starting materials and by the same technique as described in Example 1, except that a drying cylinder temperature of 150 ° C was used and the finished product was rolled without length reduction. Due to the use of the higher cylinder temperature, the fiber layer could be removed from the drying cylinder without the need for a crepe. This allowed the material to be wound at the same speed as the one at which it was formed.

EXAMPLE 3

A fiber product was prepared in the same manner as described in Example 1, however, instead of 95% cellulose pulp, 93% cellulose pulp and 2% thermosetting melamine binder (of the type "Cymell 411") was used. A product having a weight of 25 g / m was obtained. To obtain a sufficiently high wet strength, the fiber product removed from the drying cylinder was heated for 1-2 seconds to a temperature of 160 ° C.

EXAMPLES 4-6

Fiber products of various weights were prepared by the methods described in Examples 1-3. Thus, by the method of Example 1, a fiber product having a weight of 75 g / m (Example 4) was prepared, by the method of Example 2 a fiber product weighing 75 g / m (Example 5) and by the method 2 according to Example 3, a product weighing 80 g / m (Example 5). The products with weights of 75 g / m and 80 g / m were suitable for making kitchen rolls and paper towels. The product containing melamine binder had a greater wet strength than the other products.

EXAMPLE 7

The procedure of Example 3 was repeated but using melamine binder of the type "Cymell 430". The preliminary studies of the product showed no significant differences compared to the product prepared according to Example 3.

EXAMPLE 8

A fiber product was prepared as described in Example 1 but with the difference that part of the cellulose pulp was replaced by thermoplastic polyethylene in fiber form. The polyethylene fibers were approximately the same length as the cellulose fibers in the pulp material. The material introduced on the molding band had the following composition: 80% cellulose fibers, 15% polyethylene fibers and 5% oxidized starch. After the fiber layer was formed, a 3% solution of oxidized starch in water was sprayed.

The product formed was more yellowish than the product made according to Example 1 but had a quality which made it suitable for use in the manufacture of toilet paper.

EXAMPLE 9

A product was prepared by the method of Example 1, however, upon rolling, a 15% starch solution was applied to the molding tape prior to the application of fibers thereon.

A stronger but not quite as soft product was obtained as in Example 1.

EXAMPLE 10

A fiber product was prepared by the procedure described in Example 9, however, the solution containing oxidized pathway, which was sprayed before contacting the fiber layer with the drying cylinder, had a concentration of only 2%.

A product suitable for making o kitchen rolls having a weight of 60 g / m was obtained.

In the manufacture of products as described in Examples 1-10 above, the material thickness is dependent on the pressure at which the fiber network of the metal mesh is pressed against the drying cylinder and the temperature of the cylinder. Generally, however, for products weighing 30 g / m, a thickness of 0.3-0.4 mm is obtained, and for products weighing 75 g / m, a thickness of approx. 0.8-0.9 mm.

All of the products made according to the above examples had a distinctive embossing pattern similar to the metal mesh structure. The fibers were more strongly bonded within the embossed areas, and the products obtained had both considerable strength and volume, making them suitable for use in the manufacture of toilet paper and napkins.

Claims (9)

12 144426 A method of producing web-shaped fiber products, wherein an endless, air-permeable molding belt is passed past a number of fiber distributors disposed at one side of the molding from which fibers are released which are sucked in by the action of one or more suction boxes placed at the other side of the molding belt to form fiber layer thereon, characterized in that an air-permeable, endless molding band having apertures having a luminous area greater than 1 mm is used, and that the fiber material passing through the molding belt under a given fiber distributor is fed to one or more in the conveying direction of the strip after arranged fiber distributors. Method according to claim 1, characterized in that fiber distributors are used, each consisting of a plurality of fiber distributor units and that fiber material is supplied to each fiber distributor directly from one or more defibrators. Method according to claim 1 for the manufacture of cellulose fiber products, characterized in that a molding tape is used, the openings of which have a dimension in the transverse machine direction of from 0.5 to 1.5 mm. Method according to claim 3, characterized in that a molding band with openings is used, the dimension of which in the machine direction is 2-3 times the dimension in the cross-machine direction. Method according to claim 1, characterized in that a woven metal mesh is used, wherein the warp and weft threads are arranged in canvas binding. Method according to claim 5, characterized in that a molding band is used, the distance between adjacent weft threads being greater than the distance between adjacent chain wires. Method according to claim 6, characterized in that a molding strip is used, wherein the shoot threads are rectilinear and the warp threads break at the junction points. Apparatus for producing web-shaped cellulose fiber products according to claim 1, comprising an endless air-permeable molding strip, a plurality of fiber distributors disposed along the molding strip on one side, one or more of the fiber distributors cooperating suction boxes arranged at the other side of the molding strip, characterized by: that the molding strip has openings with a luminous area greater than 1 mm and that it has piping connecting the suction box or suction boxes under a given fiber distributor to one or more of the other fiber distributors located in the conveying direction of the conveyor.