FI113974B - Manufacturing method for multilayer paper/web, involves diluting pulp suspension during formation each layer of web, by using water collected in wire water section of wire water pits - Google Patents

Abstract

The web has upper and lower layers formed using different stock solutions. The web is dewatered in the wire sections (16,26,36) of the wire water pits (17,27,37). The pulp suspension is diluted during formation of each layer using water from a wire section.

Description

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The present invention relates to a process according to claim 1, and to a process for producing a multilayer web.

Processes for making a multilayer web are known in the art, in which, in order to return the tap water to the multilayer headboxes, the tap water of the wire section is led to the layer of the head box where it originally came.

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European Patent Publication No. 0 664 356 discloses a method and apparatus for improving the quality of multilayer papers, wherein the water from the former is divided so that the waters of the surface layers are directed to the surfaces in the multilayer headbox and the waters of the middle layers to the middle layer.

In the method and apparatus for making a multi-ply paper web disclosed in US Patent No. 4,477,313, the collection of tap water from the former is carried out by passing the water to be collected first to the bottom layer and then to ». The water to be collected is transferred to the middle layer.

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Fl patent application 992670 discloses a method for producing a multilayer web and a multilayer web having two webs and at least one headbox is a multilayer headbox and the tap water is collected from the stripper so that the waters of the topsheets are conducted to the topsheet layers and

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In short circuits known in the art, material flow in the pulp * * · ';;; * from manufacturing goes through a short cycle process to the machine and any rejects * ·; * 'from the following processes are returned to the previous process or redirected to fiber recovery::: 30. When the end product, such as cardboard, is made up of multiple layers, the unwanted materials accumulate in different layers in a short cycle, depending on the materials that are applied to each layer. In order to reduce the effects of these undesirable undesirable substances, various additional processes have to be added to the circulating waste systems, such as dispersing the surface layer of recycled cardboard, reducing the undesirable effects they cause, resulting in costs and also increased energy consumption.

Recycled fiber contains not only recycled fiber material but also other materials such as carton treating agent, surface treatment agent such as wax, bi-10 nuclei and various dirt particles from rubber and tape processing etc. which form sticky substances. A particular problem is that without the expensive additional processes of the type described above, when using recycled fiber for the production of paper / board pulp, both the machine and the end product suffer from the problems caused by the harmful substances from the raw materials. In the manufacture of a moniker-15 slurry from recycled fiber, there is a particular problem with the dirt particles that come with the recycled fiber when recirculating the tap water for short-term reuse. Machine parts eg. adheres to various particles, tacky materials such as waxes and bitumen from recycled fiber raw materials. Here too, the surface quality of the final product is undesirable because it forms a sticky; 20 patches caused by substances and / or contaminated machine parts.

t ·,! '! In prior art processes, mass flow is processed and retrieved from light particles such as plastic, heavy particles, sticky particles, and colored particles. These go through different sorting processes, which; ·, ·, 25 also the fiber raw material is sorted into short, long and medium fibers. This- * · • », ···. Depending on the end product, for example, a long fiber is selected for the surface layer, whereby the strength is achieved. If material with long fibers on the surface is desired, »» «;;; so recycled fibers usually come with sticky and other harmful particles. As a result, extra long processes have been used to sort long fibers to obtain, for example, sticky and other harmful substances from the powder. However, such additional processes consume energy.

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An object of the invention is therefore to reduce the energy consumption of the treatment.

5 In prior art applications, adhesives and other noxious substances accumulate in the system and thus cause problems. If they are due to surface or backing layers, they will hit parts of the machine, causing process problems and cleaning problems and need for cleaning.

It is an object of the invention to reduce the effects of harmful substances in the paper or board machine and in the end product that accompany the recycled fibers.

The object of the invention is to provide a solution to minimize, or at least minimize, the problems described above.

In order to achieve the foregoing and further objects, the process according to the invention is essentially characterized by what is stated in the characterizing part of claim 1.

20 '' The invention provides a situation with fewer machine cleaning problems and '; 1; 'Fewer defects in the final product. This in turn reduces the amount of energy required to make the product. This will also reduce the environmental impact as the process will be less wasteful. The invention achieves a better utilization rate of the compressor, since it causes fewer process and cleaning problems.

4 113974 the tap water leaving the strip layer is led to the surface layer and the water containing the tack layer and other harmful substances from the surface layer is led for use in the middle layer stripping and the water leaving the strip strip back is led back to the back layer. For example, in a two-fold rosin, clean water is introduced into the surface and dirty water and sticky substances and other harmful substances are introduced into the background.

In accordance with the invention, sticky and other harmful substances which are carried with water streams are directed to layers where they cause less problems. In this way, the adverse effects of undesirable substances such as sticky materials and bitumen can be reduced, for example, on the surfaces of a fibrous web product. This, in turn, can reduce the amount of additional processes such as dispersion in the preparation.

The process according to the invention is designed and dimensioned in a new way which further provides new possibilities for optimizing the process and the end product, for example with respect to the filler which becomes the raw material of the desired layer. The invention thus provides the advantage of relocating the circuits to be made to the process. The web works as part of the cleaning process and at the same time provides new functions for the wire section.

20 '; '; 'The invention will now be described in more detail in the accompanying drawings, in which:'; however, the details of which, however, are not intended to be construed in any narrow sense * · ,,; restrict.

... Figure 1 schematically illustrates an embodiment of the invention.

Fig. 2 schematically illustrates an embodiment of the invention.

Figure 3 schematically illustrates an embodiment of the invention, i 30

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In one embodiment of the invention shown in Figure 1, the medium fiber containing mass atom is designated by reference numeral 10, the short fiber reference atom by number 20 and the long fiber containing atomic mass atom by reference numeral 30. The pulp 10, 20, 30 is pumped into a feed tank 11, 21, 31. The pulp 12, 22, 32 is led to the mixed mass 13, 23, 33. The overflow of the machine tank screen 12, 22, 32 is recycled back to the corresponding mass atom 10, 20, 30. From the mixer 13, 23, 33 to the 10, 20, 30 machine tank screen The pulp from 12, 22, 32 is diluted with tap water from a tap water well 17, 27 37 to a headbox consistency and is further passed through a screen 14, 24, 34 to a headstock 10, 25, 35. From the headboxes 15, 25, 35 a pulp suspension is fed to the wire section 16, 26, 36, wherein the formed web is dewatered. The web formed by the wire section 16 is guided to the backing layer of the finished web. The web formed by the wire section 26 is guided to the middle layer of the web to be manufactured and the web formed by the wire section 36 is guided to the top layer of the web to be manufactured. The tap water exiting the web from the slit portions 16, 26, 36 is led to the tap water well 17, 27 and 37, respectively, for each layer. The overflow of the tap water 17, 27, 37 is led through the tank 18, 28, 38 to the mass atom 10, 20, 30 or discharge, and the tap water for the tap water backing layer 17 is led back to the mixer 13 to the tap headbox layer 15. 27 of the 20 are fed to the surface layer mixer 33. And from the surface layer tap 37, the tap water is led to the middle layer mixer 23. In this> · *, sticky and other such substances may be removed from the surface layer so that they do not interfere with processing. .

25 ..! Fig. 2 shows like parts with reference numerals corresponding to Fig. 1. The embodiment of the invention shown in Fig. 2 differs from the embodiment of Fig. 1 in that the backwater from the backwater trough 17 is led to a channel leading to the middle layer * 'to the mixer 23. From the middle trough 27, the tap water is led to * 30 channels leading to the surface tumbler 33 and from the surface layer wire 6 113974 water well 37, the tap water is led to a channel that leads to the surface layer mixer 13.

In Fig. 3 the same reference numerals are used for the parts corresponding to Figs. 1 and 2. 3 differs from the above embodiments in that the tap water from the middle layer tap water 27 is led to the backing mixer 13. The tap water from the background layer tap 17 is led to the top layer mixer 33 and the tap water from the top layer tap 37 to the middle layer mixer 23.

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In the embodiments shown in Figs. 1-3, the tackifiers are led, at least in part, with the desired layer, preferably the middle layer, if necessary, to the backing layer. In this case, the adhesives do not contact the surface layer and do not stick to machine parts or cause surface defects on the finished web. Sorted clean water 15 is led to the surface and dirty water to the middle and intermediate to the backing layer.

The embodiments shown in Figs. 1-3 relate to the production of a three-layered web, but for example to the production of a two-layered web to the surface layer *. · Drain clean water and dirty water in the background.

Γ 20 * * '·'. * The invention has been described above only with reference to some advantageous application examples * k »* · '**', the details of which, however, are not intended to be narrowly limited.

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Claims (10)

1. A method for producing a multilayer paper or cardboard web containing recycled fiber, 5. in which the multilayer web is formed by at least two layers, whose pulp compositions differ from each other, • in the molding of each layer, the pulp suspension is diluted with wire water to inlet thickness and is discharged with the inlet carriage on the wire portion, where water is removed from the web and these layers are blended together to form the multi-layered web, characterized in that • the wire water which settles the wire portion in the formation of each layer is conducted for use in diluting the pulp which should be fed to another layer. 15 2. A method according to claim 1, characterized in that sticking agents and other harmful substances in the wirewater are led to another layer. V Method according to claim 1 or 2, characterized in that in the process': the tacking substances and the other harmful substances which are carried by the wirewater are led to a *. · Middle layer in the manufacture of a least three-layered web. A method according to claim 1 or 2, characterized in that in the process * ··· 'the tacky substances which are led with the wire water are led to an underlying layer in the manufacture of a cross-layered web. 11 «» t · * · 5. A method according to any one of claims 1 to 4, characterized in that in the process. the strip of wire water is filtered and the pure water is led into a surface layer, the water that contains pour particles of dirt and the like is led into a middle layer. Γ · .. 30 * · »» 113974 6. A method according to any of claims 1-5, characterized in that in the method, the wastewater containing a small amount of dirt particles is led to an underlying layer. 5 Method according to any of claims 1-6, characterized in that in the process the mass is pumped until a mass atom (10,20,30) with a feeder pump (11,21,31) into a machine container (12,22,32). ), where the mass is led to a mixer (13,23,33), until the mixer (13,23,33) is passed through a screen (14,24,34) to the inlet sludge (15,25,35) . 8. A method according to claim 7, characterized in that the wirewater is led to a wirewater well (17,27,37) and the wirewater from the wirewater well (17) is directed back to the mixer (13) which likes to enter the inlet carriage (15). for the underlying layer, the wire water of the middle layer from the wire water well (37) to the mixer (33) leading to the surface layer and the wire water of the wire water well (37) to the surface layer of the mixer (23) for the middle layer. 9. A method according to claim 7, characterized in that the wirewater ffn the water layer (17) for the underlying layer is led to a channel leading to the mixer (23) for the middle layer, the wafer water ffn. medium water well (27). The layer is led to a channel leading to the mixer (33) for the surface layer and the wire water from the surface water well (37) for the surface layer is led to a channel leading to the mixer; '(13) for the underlying layer. 25 10. A method according to claim 7, characterized in that the wirewater from the middle water well (27) for the middle layer is fed to the mixer (13) for the underlying *! the layer, the wirewater from the wirewater (17) for the underlying layer is directed 5: to the mixer (33) for the surface layer and the wirewater from the wirewater (37) for t # ''; The surface layer is guided into the mixer (23) for the middle layer. : '> 30