FI122145B - Process and system for manufacturing a fibrous product - Google Patents

Description

METHOD AND SYSTEM FOR MANUFACTURING A FABRIC PRODUCT

OBJECT OF THE INVENTION 5

The invention relates to a process for preparing a fibrous product. The invention further relates to a system for producing a fibrous product.

Background of the Invention

Fiber-containing sheets with a higher proportion of nanofibrillated cellulose (NFC) have been found to have particularly interesting properties. The relative proportion of the surface of the body relative to the volume of the body increases as the body shrinks, which often results in very different properties of the nanoparticles from those of the macroscopic bodies. Industrial properties of interest for nanocellulose include, for example, its particularly high tensile strength, very low porosity and partial translucency. These properties, among other things, make nanocellulose the desired raw material for products containing a variety of industrial applications.

The use of nanocellulose as a raw material for a fibrous product such as paper or board is still limited for the time being by various practical problems. Nanocellulose is a gel-like material, even at low consistency, and removal of water from high-nanocellulose-containing fibrous material is often slow. In addition, the nanocellulose S2 loose adheres to the easy-to-use wire, since small g 30 particles of nanocellulose adhere particularly firmly to the woven fabric, which can cause problems in the manufacturing process of the fibrous product containing nanocellulose I '- 5.

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§ Extracting the wire requires quite a lot of force. The problems of wire bonding ™ are often exacerbated by the fact that the nanocellulose 35 has a relatively low internal strength when wet, so that the force required to release the web from the wire may be greater than the internal strength of the above-mentioned wet fiber suspension. In particular, if the amount of nano-cellulose in the pulp suspension is relatively high, the intrinsic wet strength can easily remain so low in relation to the forces between the web and the wire that it is particularly problematic to separate the web from the wire intact.

In prior art papermaking processes, the web is generally removed from the fabric at a very early stage while the web is still low in dry matter, so adding nanocell 10 loose to the pulp suspension with webmaking machines can result in particularly low running speeds on webmaking machines. This problem may be accentuated by the fact that the removal of water from the nanocellulose-containing web may be slower than usual.

In addition to the aforementioned problems, another problem with nanocellulose may be that current wires commonly used in production are generally very rare for small particles, whereby the retention rate of 20 nanocellulose may be particularly low when using such wires.

Under laboratory conditions, the aforementioned pulp release problem from the wire and the wire density problem have been solved e.g. using a special pie-25 mesh wire, so-called. a fine wire having a density of, for example, 200 ^ mesh. In this case, the retention rate of the nanocellulose is generally sufficiently high. In addition to having high fiber nanocellulose sheets first fabricated on a fine wire, laboratories still have $ 2 dried. fiber sheets over a fine wire until the dry matter content of the sheets has increased. Sheets substantially containing nanocellulose have a significantly higher dry strength than wet strength, so that a sufficiently dried sheet can generally be removed from a long wire without problems.

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35 The fibrous web tends to shrink as it dries. Since the web-like product is typically considered tensile to the web longitudinal direction 3, problems with shrinkage shrinkage generally occur in the cross-web direction. These problems can occur both in the manufacture of conventional fibrous products and in the manufacture of fibrous products substantially containing nanocellulose. Since drying shrinkage occurs as the web dries, it may be possible to avoid the problem by operating the web for a longer period of time in contact with the wire cloth on which the web is formed.

On a large scale, such as paper mills, there has been no practical solution to these problems mentioned above. Thus, there would be a need for solutions that would enable the fibrous product to be manufactured with better solutions in production processes by various web-making machines or the like.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a solution to the above problem of low solids content by maintaining the fibrous product in sufficient contact with the wire fabric on which the web is formed. A preferred embodiment is intended to reduce the problem of detaching a fibrous web containing nanocellulose from a wire in the manufacture of a web-like fibrous product by drying the web sufficiently before removing the web from said wire. Another preferred embodiment is intended to reduce and / or control the transverse drying shrinkage of the web.

In the solution according to the invention, the stripping of the web can be performed at a stage where the dry solids content of the web reaches a predetermined limit value. According to a preferred embodiment g 30, this is achieved when the intrinsic strength of the web is greater than the forces between the web and the wire. In this case, the web may be detached from the vii-5 intact. According to a preferred embodiment, considerable amounts of nanocellulose can be added to the product, g so that the web can be further removed from the fabric without breaking the web. According to another preferred embodiment, the web can be detached from the forming fabric 4 when the dry solids content of the web is such that the transverse drying shrinkage of the web is reduced by the desired amount.

According to one embodiment of the invention, the web is supported by at least one wire from the formation of the web to at least the press section, for example at least over the first press nip of the press, preferably to the drying section of the web making machine. Hereby, the web is supported by the same, at least one wire, substantially continuously from the web formation to at least said step. According to one embodiment, the web to be manufactured is supported by at least substantially half of the press portion by the action of the same wire. According to one embodiment, the web is supported by the same wire from the formation of the web at least over the first drying group of the drying section, preferably up to about half the drying section. According to one embodiment, the web is supported by the same wire over the entire drying section, for example until the web is close to the first calender, coating unit or roll of the web making machine.

According to one embodiment, the web is supported by only one long wire, i.e., only one side of the web. According to a preferred embodiment, when using a long wire, the opening size of said long wire is preferably selected so that the retention of the fibrous material containing nanocellulose can be improved. According to one embodiment of the invention, the webs 25 are generally supported by the so-called denser wires used in papermaking. hienoviiroilla. According to an exemplary embodiment, these fine wires are present on both sides of the web.

According to one embodiment of the invention, the long wire in contact with the web g 30 is supported by separate wires, which may be less wires than the long wire. In this case, the long wire is preferably placed between the pulp and 5 ordinary wire. These so-called. ordinary wires can be placed in the strip

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The machine may be placed in the machine for several distances over the entire length of the long wire, or may be placed, for example, only on the drying section.

According to a preferred embodiment, the web is supported on at least the drying section on both sides by long wires, and the conventional fabrics are either not used at all or are used only on the drying section.

The process for producing a fiber product 5 according to the present invention is essentially characterized in what is claimed in claim 1. The system for producing a fiber product according to the present invention is essentially characterized in what is set out in claim 6.

10 Description of the drawings

The invention will now be described in more detail with reference to the accompanying drawings, in which Figure 1 is a side view of an exemplary embodiment of a web making machine having an exemplary wire solution, and Figure 2 illustrates a preferred detail of an embodiment 20 of wire 1.

DETAILED DESCRIPTION OF THE INVENTION For the purposes of this application, a web making machine refers to a machine for producing a web containing fibrous material. Such a machine may be, for example, a paper machine, a board machine or the like.

1 to $ 2 A web is a planar, continuous web-based product 30, the basic structure of which is a network consisting at least in part of fibers or parts of fibers. At least some of the fibers contain cellulose. In addition, the web may contain various amounts of other substances such as

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§ various fillers, coatings and additives. In addition, water is usually used in the manufacturing process. The final product of the manufacturing process may be, for example, paper, cardboard, thin wood plastic composite or the like.

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For the purposes of this application, a fine wire is a dense wire having a mesh number of at least 130, 140 or 150. A fine wire may also be dense, such as a wire having a mesh of at least 180, at least 200 or at least 220. a prior art wet wire or drying wire generally used in a web making machine. The Mesh number indicates how many yarns in a filter, such as a wire, are within one inch.

By long wire, in this application is meant a wire which starts substantially from the forming section (wire section) and extends at least to the press section, preferably to the first press nip of the press section.

Normal wires 9 refer to commonly used wires, including both wet wires and dry wires. Normal wires 9 may also be referred to as another wire 9 in this application.

Nanofibrillated cellulose (NFC) refers to a fibrous material in which individual microfibrils are separated. The nanocellulose particles typically have a length of up to 1 µm and a diameter of less than 1 µm, typically from about 2 nm to about 200 nm. The dimensions of the nanocellulose particles depend on the method of preparation of the nanocellulose. Unlike conventional pulp milling, the production of nanocellulose tends to crush cellulose fibers. Nanocellulose is typically a transparent, gel-like material with

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Figure 1 shows a preferred embodiment of the invention. Fig. 2a 2 shows a preferred detail of the wire arrangement of the embodiment of Fig. 1. Figures 1 to 2 show a web making machine 1, a headbox 2, a web forming section (wire section) 3, a press section 4, a drying section 5, a calender 6, a roller 7, a long web 8, normal webs 9, and a section web.

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35 Normal wires 9 may be present in the solution according to the invention, but it is also possible that the solution 7 according to the invention does not include any normal wires 9. Normal wires 9 may be omitted, particularly from those parts of the machine having at least one long wire 8. FIG. according to the longitudinal fabric 8 is preferably a fine fabric. According to a preferred example of the invention, in the web-5 making machine, normal wires 9 can be used at substantially the same positions with the long wires 8 such that the normal wire is at least partially inserted between the wires 8 and the rolls of the web making machine. In this case, the normal wire 9 can prevent the wear of the long wire 8 or the long wire 8. This may be advantageous because the long wire 8 can be quite an expensive wire, whereby it is often more advantageous to replace the normal wire 9 than the long wire 8.

Typically, the web 10 is fed from the headbox 2 to the web forming section 3. The longitudinal webs 8 have at least one piece 15 of the machine according to the invention and their suitable number generally depends on the type of machine 1 producing the web 10. Generally, there are exactly one or exactly two long wires 8 depending on the type of web making machine 1. The long wire 8 may be supported by the web forming section 3 with the normal wire 9 (a). The normal wire 9 (a) can then slow down the wear of the long wire 8.

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From the web forming section 3, the web 10 is supported by the at least one long web 8 in the drying process, typically to the press section 4, where the long web 8 may be supported by normal press sections 9b, 9c, said normal webs 9b, 9c). One or both of the normal webs 9b, 9c) g of the press section may also be absent from the solution of the invention if replaced by a long web 8. According to a preferred embodiment, the long web 9 8 is disposed to support web 10 from web forming section 3 over the first press nip whereupon the long web is guided to g 30 again to the web forming part 3. According to another preferred embodiment, the long web 8 is disposed to support the web over the second press nip and / or the third press nip of the press member 4 ^, followed by the web

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§ is detached from the longitudinal wire 8, which longitudinal wire 8 is subsequently guided to the web forming part 3.

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Preferably, from the press section 4, the web 10 is further guided to the drying section 5. According to a preferred embodiment, the web 10, supported by at least one same longitudinal wire 8, is guided from the web forming section 3 to the drying section 5. forming member 3, up to a desired imaging group, such as a first imaging group, a second imaging group, a third imaging group, a fourth imaging group or a fifth imaging group. Thereafter, the web 10 is removed 10 from the longitudinal wire 8, after which the web is guided forward in the process, for example it may be in contact with normal wires 9, as is customary in conventional papermaking. The drying section 5 may have, in addition to the long wire 8, one or more normal wires 9d-9g. At least a portion of the normal wires 9 may be on the drying part 15 of the web making machine 1 at substantially the same position as the long web 8 between the long web 8 and one or more rollers of the web making machine 1, said normal webs 9

The longitudinal wires 8 may be one piece, whereby the long wires 8 may be located on one side of the web 10, or, for example, there may be two pieces of long wires 8 such that the first longitudinal wire 8 is located on one side of the web 10 and the If there are two long wires 8, if desired, normal wires 9 may be si-25 connected, for example, to one long wire 8, or to both long wires 8. In some cases, placing ™ normal wires 9 in connection with both long wires 8 may be advantageous, for example, to prevent wear of the long wire 9. If the machine has two long wires 8, i.e. preferably one long wire 8 on each side of the web, the stripping of the web from the long wires 8 can be either at substantially the same time or

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at substantially different times, one at a time, by stripping web 10 first from one longitudinal wire 8 and then from another longitudinal wire 8. Often, if it is only possible for the operation of the process, it is more desirable to use only one longitudinal wire 8 to minimize costs.

35 In some cases, however, it is necessary to use two long webs 9 8 for at least part of the web drying distance. Such a situation may be, for example, the so-called. other -former (Gap -Former).

The long wire 8 is preferably placed in the web making machine 1 so that the web 10 is in continuous contact with the long wire 8 at least from the forming part 3 of the web 10 to the press part 4 of the web 10, for example between the press part. If the machine 1 has normal wires 9 in contact with the long wire 8, the long wire 8 is preferably disposed so that it is between at least one normal wire 10 9 and the web 10 on at least one side of the web 10. Preferably, the long web 8 and web 10 are kept in contact with each other until the web 10 is sufficiently dry to be detached from the long web 8. The desired dry solids content of the web can be determined, for example, by intact web separation and / or cross-web drying shrinkage. . Thereafter, if desired, the web 10 may be supported by normal wires 9.

The number of possible normal wires 9, as well as the locations thereof, may vary considerably from some of the preferred embodiments of the invention described above. It is essential that the longitudinal wire 8 is disposed in the web making machine 1 such that the longitudinal wire 10 uniformly supports the web 10 from at least the web forming part 3 to the press part 4, more preferably to the drying part or to a possible first calender or machine roll. Generally, passing the long wire 8 si-25 through the calender 6 is not necessary for the desired end result g, and it may be preferable for the desired end result that the long wire 8 is not passed through the calender 6.

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o $ 2 For long wire 8, cleaning means are preferably provided to clean g 30 long wire 8 or part thereof for each round. This can be accomplished in practice by, for example, installing suitable prior art cleaning means, such as showers,

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Most preferably, this cleaning takes place at each position of the longitudinal wire 8 ° after the web 10 has been detached from the long wire 35 8, but before said position of the long wire 8 is again 10 at the web making machine where the web 10 is fed to the web forming machine. (wire section).

In order to ensure effective drying of the web 10, it is often advantageous to attach to the web forming part 3 and / or the press part 4 some separate drying acceleration means or devices. These may be some prior art organs or devices, such as suction cups and / or suction rolls. These devices, especially in the case of two overlapping wires, may need to be connected to web forming 3 and / or press 10 tin 4 more than usual and / or may be more efficient than usual.

The web 10 may be detached from the long web 8 when the web 10 has a sufficient dry matter content. The dry solids content of the web may be sufficient, for example, when it is at least 8% by weight, 9% by weight, 10% by weight, 11% by weight, 12% by weight, 13% by weight, or 14% by weight -%, but it can be e.g. also preferably at least 15 wt%, 18 wt% 20 wt%, 25 wt%, 30 wt%, 40 wt%, 50 wt%, or at least 60 wt%, due to the structure of the wire. Suitable solids content is influenced by e.g. apparatus for drying the web and in particular the properties of the wire in contact with the web.

According to one example, thanks to the invention, the proportion of nanocellulose in the pulp suspension can be set high, for example, to achieve the desired properties in the final product. Thus, by using the long-mesh solution according to the invention, nanocellulose can also be added to the pulp in quite large amounts, for example, so that at least 10 wt.%, At least 20 wt.%, At least o 30 wt. at least 40% by weight, at least 50% by weight, at least 60% by weight, or at least $ 70% by weight are nanocellulose. If necessary, for example, when the properties of the end products so determine, it is possible to add nanocellulose up to at least 80% by weight or even at least

90% by weight of the dry solids of the web 10 is nanocellulose. The solution according to the invention may in some cases be more advantageous as the nanocellulose content of the web increases, since this may make the stripping of the web 35 more difficult. partially or even completely the situation where the mechanical properties would be counteracted by the increase in the amount of nanocellulose.

According to a solution according to one example, supporting the web with mer-5 abrasive forces on the wire can reduce the transverse drying shrinkage of the web when the support is carried out for a sufficient time or even substantially throughout the drying period of the web. Especially in this case, the invention may also be useful in so-called. in the manufacture of a conventional fibrous web e.g. controlling transverse drying shrinkage. In the manufacture of a web containing nanocellulose 10, one can obtain the additional advantage that the addition of nanocellulose has often been found to have an effect of increasing shrinkage, particularly in the transverse direction of the web. When using prior art solutions, the transverse drying shrinkage of such a web can then be as high as 10%. Most of the drying shrinkage often occurs during the remainder of the drying period, whereby holding the web with a long wire 8 can substantially prevent the shrinkage shrinkage, particularly when it occurs from the forming part of the web to the end of the drying portion.

Although the invention is particularly important for nanocellulose-containing pulps, the invention can also be applied to non-nanocellulose-containing pulps. In this way, it may be possible to substantially reduce web breaks, for example with a press section. In addition, controlling the transverse shrinkage of the web may be facilitated. The invention is suitable for use in a variety of web making machines and the above examples are not intended to limit the invention. Thus, the invention is not limited to the examples set forth in Figs. 1-2 and 9 above, but is characterized by what is set forth in the appended claims.

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Claims (10)

A method of making paper, paperboard or similar fiber material, in which method 5. pulp suspension is measured on a first wire (8) in the manner of forming a web (10), and - drying the formed web (10), wherein in the method further web (10) is contacted with the same said first wire (8) after forming the web (10) continuously from the web forming portion (3) all the way to the first press nip in the press section, characterized in that the web includes nanocellulose and that the proportion of nanocellulose in the web in dry content is at least 10% by weight, at least 20% by weight, at least 30% by weight or at least 40% by weight. Process according to claim 1, characterized in that the proportion of nanocellulose in the web in dry content is at least 50% by weight, at least 60% by weight, at least 70% by weight or at least 80% by weight. 20 Method according to claim 1 or 2, characterized in that said first wire (8) is supported on at least one section, on at least one side, with a second wire (9). Method according to claim 3, characterized in that, as said second wire (9) is used in the method, a wire whose heel size is greater than the heel size of said first wire (8) and / or a wire whose total length is shorter than said first viruses (8). O 5. A method according to any of the preceding claims, characterized in that said web is kept in contact with said first wire continuously so long that the dry content of said web is at least 10% by weight, 5% by weight, 15% by weight. -%, 20 wt%, 25 wt%, 30 wt%, 40 wt% or CD § at least 50 wt%. if 6. A system for making paper, paperboard or similar fiber material, said system comprising a web making machine (1) comprising at least the following parts: - a first wire (8), 5. a web forming portion (3) with means for dispensing pulp suspension on said first wire (8) for forming a web (10), and - a pressing portion (4) comprising at least one first press nip and means for reducing the moisture content of said web, wherein said first wire (8) is placed in said machine (1) in such a way that it is arranged to run continuously from at least the web forming portion (3) to the press portion (4), said first wire (8) being arranged to support the web formed in a continuous manner from the web forming portion (3) to at least the first press nip in the press section, characterized in that the means for dispensing pulp suspension are arranged to eject pulp suspension comprising nanocellulose, whose proportion in the pulp suspension in dry content is at least 10% by weight , at least 20% by weight, at least 30% by weight or at least 40% by weight. System according to claim 6, characterized in that the system further comprises at least one drying portion (5) with means for reducing the moisture content of the web substantially under the influence of temperature, and that said first wire (8) is placed in said web making machine (1) on said web. means that the same said first wire (8) runs continuously at least from the web forming portion (3) to the drying portion (5). δ A system according to claim 7, wherein the drying portion (5) comprises a first drying group, a second drying group and a third drying group, characterized in that said first wire (8) is positioned to run continuously from the web forming portion (30). 3) at least the second drying group or the third drying group in the drying portion (5). SJ Section 9. System according to any of claims 6-8, characterized in that the system comprises, in addition to said first wire (8), a second wire (9), which second wire (9) is placed in said web-making machine (1) for supporting the first wire (8) in such a way that said second wire (8) during at least some stage is in contact with the long wire (8). System according to any one of claims 6-9, characterized in that the system comprises a further third wire placed in said web making machine (1) in such a way that said third wire also runs continuously at least from the web forming part (3) to the press part (4). ) in such a way that said third wire also supports the formed web continuously from the web forming portion (3) to at least the first press nip in the press portion. δ (M h- · o oo X and CL h- · Sj- CD σ> o o {M