KR100191140B1 - Multi-ply web former and method - Google Patents

Abstract

The present invention relates to a multi-ply paper web formed by ply bonding a base fly web (W _B ) and a government fly liner moving over a base fly forming wire 36. The government fly liner W _T is formed between the two jointly actuated forming wires 10, 20 in a convex upward convex and concave downward concave strip. Dewatering in the forming zone is effectively effected by the application of air underpressure only below the bottom surface of the government fly liner W _{T to be} formed. Water is removed from the top surface of the government fly liner W _T only by centrifugal force and gravity and wire tension resulting from passing the cavitation forming wires 10, 20 on the upwardly convex curved travel path. Yireongeot the two plies (W _T, W _B) to move the base ply (W _B) greater ply bond affinity pulp paper stock derivative further to a large concentration of gold government ply liner of to have a (W _T) between When combined with To remain on the top surface.

Description

Multi-Layer Web Forming Apparatus and Formation Method of Multi-Layer Web

The present invention relates to the formation of multi-ply paper. In particular, the present invention relates to the formation of multilayer paper of double wires. More specifically, the present invention relates to the formation of a multilayer web by double wires in which the surface of the outer layer layer bonded to the base ply web of the multilayer web is dehydrated by wire tension and centrifugal force.

In a conventional multilayer paper web product forming apparatus, a relatively coarse base web is first formed, and a second outer layer is formed to contact the already formed base web by ply bonding. The outer layer that will form the outer surface of a printed container, such as a box, is formed of a better grade pulp stock to provide a smoother, better surface. Dehydration takes place through both surfaces of the outer layer before the outer layer is brought into layer contact with the base web of the paper web sheet to form the outer layer at a commercially desirable rate. This produces paper products that meet the standards, primarily due to the quality of the pulp raw materials used to form the outer layer, but better products at high speed, regardless of the quality of the pulp and the desire to produce better products with cheaper pulp. For the need to produce or both, there was a need for an improved multilayer web forming apparatus having an outer surface that exhibits the desired printability, feel and visual smoothness, and having an inner surface with better layer adhesion properties.

In the conventional apparatus, both sides of the outer layer are reliably dehydrated. Both sides are dewatered by applying an air pressure below atmospheric pressure directly to both sides to improve water removal through both sides of the web. Once both sides are dehydrated, the fines and fillers in the pulp stock are pressed outwards in both directions to each surface of the web and removed during the dehydration process. Therefore, although the dehydration of the web is a desirable result, a large amount of fines and fillers, which greatly contributes to the layer bonding properties of the outer surface of the manufactured web, are removed, which has a detrimental effect on the quality of the web.

The above-mentioned drawbacks and defects of the layered laminated web of paper and the resulting multilayered paper product outer layer and its properties are eliminated by the invention.

According to the present invention, the outer layer of a multilayer web, sometimes described as a white top liner, is produced by dehydration through one side of the web using only centrifugal force and the tension of the forming wire on the web. The outer layer is formed in a direction opposite to the direction of movement of the substrate web on which it is laminated. In general, the upward facing surface of the top ply web is an upper outer forming wire that is recessed downwardly disposed on the web formed by the liquid pulp stock slurry discharged between the outer forming wire and the inner forming wire. Is dehydrated by the tension. In addition, one or more moisture collection devices, such as dehydration slots, which may or may not be assisted with a vacuum, assist in the removal of moisture released into the interior of the outer forming wire. Fillers and fines in the pulp stock slurry are exposed to subatmospheric (vacuum) pressures only in the lower forming wires that are generally concave downward over a relatively long distance. This makes it possible to retain more of the fines and fillers in the web, especially in the web top surface, because the movement of the fines and fillers through the bottom of the web is disturbed by the web fibers and affects the rate of removal of moisture. Dehydration, which occurs relatively slowly downwards through the bottom of the outer layer of the web, allows the web layer to take a relatively long vacuum or suction box, or a number of spaced foil blades, or a relatively long form that can be combined. This is accomplished by exposure to a pressure below atmospheric pressure applied to the dewatering zone.

Accordingly, it is an object of the present invention to provide an apparatus and method for producing multilayer paper sheets having improved layer adhesion properties.

It is another object of the present invention to provide an apparatus and method for producing an outer layer of a multilayer paper sheet in which the surface to be layer bonded is dehydrated only by centrifugal force and wire tension and gravity.

It is an advantage and feature of the present invention to provide a white top liner of a multi-layer paper sheet, which has improved layer adhesion properties, has a commercially desirable outer surface, and can be produced at high speed.

The foregoing objects, features, effects and other objects, features and effects of the present invention will be apparent to those skilled in the art upon reading the following description of the preferred embodiments which will be described in connection with the accompanying drawings.

1 is a side view of a forming apparatus showing a vacuum forming shoe of a first wire disposed over a substantial length of a forming region between a throat and a rotating roll,

2 is a side view of a forming apparatus in which vacuum forming shoes connected to two suction boxes in a lower forming wire forming a first or upper layer web are installed.

As shown in FIG. 1, the looped lower first forming wire 10 forming the upper web forms a loop around the guide rolls 12, 12 ′, 12 and the rotating roll 14. do. In the first forming wire, a downward concave defining a forming zone extending between the guide roll 12 and the rotary roll 14 is concave, and upwards to extend the first forming wire in a convex shape curve. A vacuum forming shoe 16 having a contour shape defined by a plurality of arranged foils 18 is arranged.

On the lower first forming wire 10, an upper second forming wire 20 which is moved in a looped path by guide rolls 22, 22 ', 22, 22' '' is disposed.

Guide roll 12.22 directs each forming wire 10, 20 to a converging throat 24 near the front edge of vacuum forming shoe 16. In the embodiment shown in FIG. 1, the throat 24 extends immediately after the inlet of the vacuum forming shoe 16.

The second forming wire 20 is guided so as to remain above the first forming wire over the short distance of the circumference past the surface of the rotary roll 14. The rotary roll 14 is a suction roll having a vacuum chamber 26 extending between the circumferentially spaced seals 28, 30. The first and second forming wires are shown engaged over a short distance past the upstream vacuum chamber seal 28.

The loop-shaped second forming wire 20 is provided with a save-all 32 which can take the form of a so-called auto slice. In any shape, the drip tray or auto slice represents a blade, lip, or slot 33 disposed in close or pressureless contact with the inside of the looped second forming wire 20. One or more ribs or slots 33 may be used.

The head box 34 is arranged to direct the liquid slurry of raw fiber into the throat 24. For example, depending on operating parameters such as machine speed, concentration of raw material, and the type of forming wire already used, the head box slice nozzles are directed in one or the other direction of the forming wire.

Under one upper web forming device (former) described above, the base layer web forming wire 36, and that over the base layer web (W _B) is formed in the upper web forming apparatus upstream by other means. The pivoted guide roll 38 has a base web forming wire 36 near a portion of the outer periphery of the rotary roll 14 from one point of the back seal 30. Therefore, the upper web W _T is brought into contact to travel with the base web W _B , and layer bonding occurs between the webs during this contact period. Transferring the thus formed composite multilayer paper sheet to the base web forming wire 36 is assured by applying a vacuum pressure to the transfer box 40.

The vacuum forming shoe 16 has an air pressure source below atmospheric pressure to provide a vacuum pressure to the lower side of the web formed between the wires 10 and 20 running together on the foil blade 18 of the vacuum forming shoe 16. 42 is optionally connected. Water is removed from the inner surface of the looped second forming wire by the drainage device 44, and water from the looped first forming wire is removed by the drainage device 46.

In the various forms shown in FIGS. 1 through 2, corresponding elements in each of the figures have been appended with English letters to distinguish between corresponding elements in the various figures. Likewise, the same elements in a particular figure will be distinguished by appending a different number of primes (') after each element number.

As shown in FIG. 2, the dewatering element of the first forming wire 10a includes a vacuum forming shoe 16a and two vacuum forming boxes 17a and 17a '. The vacuum forming box 17a ′ in the downstream direction carries the newly formed upper web W _T over the first forming wire.

The second auto slice 48a 'disposed between the first auto slice 48a on the vacuum forming shoe and the two vacuum forming boxes 17a and 17a' is disposed on the looped second forming wire 20a. The two auto slices have leading ribs 33a and 33a 'which are mounted in close contact or in pressureless contact with the inside of the looped second forming wire 20a. The head box 34a discharges a fiber stream of liquid raw material into the throat 24a formed between the forming wires 10a and 20a converging on the guide rolls 12a and 22a.

In the above-described form, the rotary roll 14a, which is a flat roll without vacuum chamber, moves the first forming wire to the vicinity of the surface of the rotary roll such that the rotating roll 14a is brought into contact with the base web W _B carried in the base web forming wire 36a. Move it.

In the embodiment shown in FIG. 2, the vacuum forming shoe 16a is connected to an air pressure source 42a below atmospheric pressure, and the vacuum forming boxes 17a and 17a 'are below the atmospheric pressure source 52a and 52a'. ) The contour of the wire contact surface of the vacuum forming shoe and the vacuum forming box is concave downward and convex upward. The surface of the vacuum forming shoe is formed by a series of spaced apart foils that are spaced in the machine direction, parallel and in the machine transverse direction, and the contour of the vacuum forming box forms a vacuum pressure on the underside of the looped first forming wire. It consists of a perforated arcuate surface such that a hole through the cover is provided for application.

In operation, with reference to FIGS. 1 and 2, the head box releases the liquid raw slurry into the throat between the forming wires running together. Since the application of only sub-atmospheric air pressure to the fibrous raw material slurry between the forming wires is provided by a vacuum forming box or a vacuum forming shoe under the first forming wires 10, 105, the moisture is deposited in the upper upper web W _T. Through and out from the raw material slurry into the loop-shaped first forming wire. Due to the tension of the second forming wires 10, 10a over the raw material slurry over the first forming wires, the moisture is trapped through the upper web W _T formed between the first and second forming wires 32. Or to the outside into the auto slices 48a and 48a '. Water is also discharged outward through the top surface of the upper web by gravity and centrifugal force, which are generally horizontally positioned and slightly downwardly curved moving portions running together in the concave forming zone. The blades of vacuum forming shoes 16 and 16a operating with or without vacuum pressure below atmospheric pressure slowly drain moisture into the vacuum forming shoe. In the downstream direction, i.e. at the point where more webs are dewatered, a vacuum pressure below the higher atmospheric pressure is applied to the vacuum forming box 17a 'to further dewater the upper web through the bottom surface.

In all embodiments, by applying an air pressure less than atmospheric pressure only below the upper web through the first forming wire, the filler and fines of the raw material slurry are moved downwards toward the lower surface of the upper web. Thus, although some of the fine powder near the bottom surface of the upper web over the first forming wire is removed from the web, a relatively large amount of fine powder near the upper surface of the upper web adjacent to the second forming wire during dehydration performed by air pressure below atmospheric pressure. Remains in the web. Not only does the fine powder remain in the web, but also no subatmospheric air pressure is applied to the raw material slurry between the forming wires through the second forming wire, so that most of the fine powder originally present in the raw material remains in the web. In other words, the force that removes moisture from the top surface of the upper web is the centrifugal force and the forming wire tension and the gravity applied in the portion extending slightly below the forming wire path of the forming portion arranged substantially horizontally. Therefore, the moisture discharged through the upper (second) forming wire only needs to be collected by the drip tray or the auto slice. That is, moisture is not discharged through the upper web forming wires by the elements.

Therefore, a relatively large amount of fine powder remains on the upper surface of the upper layer web to be formed, and this upper surface is a surface to be brought into layer contact with the upper surface of the base web W _B on the rotary roll. Since layer bonding is reinforced by a large amount of fines in one or both sides of the web at its interface, layer bonding between the upper web W _T and the base web W _B is enhanced by the present invention. This enables layer bonding in low water content webs and fast machine speeds, or in combinations thereof.

According to the present invention, dehydration is performed upward (through the second forming wire) and downward (via the first forming wire), and the dehydration is controlled as described above. More fines remain on or near the top of the upper web, resulting in better layer adhesion, and more fines and fibers remain in the entire upper web as pressure is applied below the atmospheric pressure only on the lower surface through the first forming wire. . In other words, the bottom of the upper web is also of high quality. This enhances the smoothness and printing properties of the upper web of the composite multilayer web W. FIG.

Of course, variations of the apparatus and method described above are possible. For example, the throat can extend from upstream of where the upper web forming wire is guided to move in substantially the same direction from where the wire converges. It has also been described that the vacuum forming shoe and the vacuum forming box are operated in conjunction with air pressure below atmospheric pressure, but under certain circumstances, they may not be so. Finally, the terms web and sheet and paper should be understood to include the term board.

Claims (10)

A method of forming a multi-layer web, comprising: forming a base ply web on a moving porous base forming wire 36, the looped first forming wires 10, 10a and the looped agent Bringing the forming wires 20 and 20a into a contact state running together in the forming zone extending between the guide means and the rotating means arranged in the loop-shaped first forming wire, the loop-shaped first forming wire and the loop Releasing a stream of liquid top ply web material over one or both of the type second forming wires and into a throat formed by the converging first forming wires and the second forming wires, An air pressure below atmospheric pressure is applied to the stream of raw materials only below the concave portion below the travel path to dewater the upper web (W _T ) stream through the first forming wires 10, 10a to form the lower surface of the upper web. Ride Discharging water upward through the second forming wire on the isopath only by wire tension and centrifugal force to form an upper surface of the upper layer web, on the convex curved inner surface upward of the second forming wire (20, 20a) Collecting the moisture discharged through the second forming wire in the second forming wire at one or more locations, and making the top surface of the upper web come into contact with the base web W _B so as to contact the layered web. Consisting of a forming step, in the form of a continuous contour of the forming zone, the inner surface of the first forming wire is recessed downwardly and the inner surface of the second forming wire is convexly curved upward of the travel path. Multilayer web formation method. The method of claim 1, further comprising: guiding the second forming wire in a direction separate from the first forming wire downstream from a dehydration position made through the first forming wire, and downstream of a position at which the second forming wire is separated and guided. Further dewatering the upper web by air pressure below atmospheric pressure through the first forming wire. 2. The first forming wire of claim 1, wherein the stream of upper web material is discharged to the first forming wire upstream of the throat and before the first forming wire and the second forming wire converge and run together in contact with the first forming wire. And dewatering the stream of the upper web paper stock downwardly within. 4. The method of claim 3, further comprising: guiding the second forming wire in a direction separate from the first forming wire downstream of the dewatering position made through the first forming wire, the downstream of the position at which the second forming wire is separated and guided. And further dewatering the upper layer web by air pressure below atmospheric pressure through the first forming wire. 4. The method of claim 3, wherein the stream of upper web material is dewatered by applying an air pressure below atmospheric pressure before the first forming wire and the second forming wire converge. Apparatus for forming a multi-layered paper web, comprising: a rotating means rotatably mounted in the apparatus, a guiding means, a loop base web forming wire 36 for conveying and dewatering a base web, and a contact state converged in a throat and traveling together Throat to start the formation of the loop-shaped first forming wires 10 and 10a and the second forming wires 20 and 20a and the upper layer web having the lower surface and the upper surface to form the upper layer web W _T arranged to be Hyd box means 34, 34a for supplying a liquid upper web raw material slurry into (24, 24a), and dewatering the stream of the upper web raw material downward through a first forming wire forming an upper web to form a first forming wire. Dewatering means 16, 16a, 17a, 17a 'utilizing air pressure below atmospheric pressure, disposed only within the first forming wire to form an upper layer web having a lower surface thereon, the looped second forming only by centrifugal force and forming wire tension wire Water receiving means (32,48a, 48a ') for receiving the water discharged upwardly through the upper portion, and the first forming wire (10, 10a) so that the upper surface of the upper layer web is dewatered upward only by centrifugal force and forming wire tension. A substantially continuous web forming zone comprising guiding means 22 ''',22a''' for guiding the second forming wires 20, 20a to be separated from the web and extending between the guiding means and the rotating means. In the outline form, the first forming wire and the second forming wire is concave downward in the inner surface of the first forming wire in the path running together, the inner surface of the second forming wire is curved convex upwards, An upper surface of the upper web is opposed to the second wire, and moisture receiving means for receiving moisture disposed in one or more positions is disposed on the inner surface convexly curved upward of the second forming wire, and the rotating means And the first forming wire and the web are arranged to guide the first forming wire and the web in contact with the base web so that layer bonding is made between the top surface of the layer web and the base web. 7. The method of claim 6, wherein the head box means discharges the upper web raw material to the first forming wire and the first forming wire to form the upper web upstream close to the position where the second forming wire converges. A multilayer paper web forming apparatus, characterized in that it is disposed below the first forming wire downstream of the position where the first forming wire and the second forming wire converge. 7. Apparatus according to claim 6 wherein the rotating means (14, 14a ') comprises a suction roll. 7. Apparatus according to claim 6, characterized in that the water receiving means (32,48a, 48a ') for receiving water comprises a drip tray (32) or an auto slice (48a, 48a'). 7. Multilayer according to claim 6, characterized in that the dewatering means using air pressure below atmospheric pressure comprises a first vacuum forming shoe 16a and at least one vacuum forming box 17a downstream of the vacuum forming shoe. Paper web forming device.