EP3919679A1

EP3919679A1 - Treatment section of a production line for producing a barrier coated fiber web

Info

Publication number: EP3919679A1
Application number: EP21170096.8A
Authority: EP
Inventors: Seppo Luomi; Timo Nurmiainen; Mika Viljanmaa
Original assignee: Valmet Technologies Oy
Current assignee: Valmet Technologies Oy
Priority date: 2020-06-01
Filing date: 2021-04-23
Publication date: 2021-12-08
Anticipated expiration: 2041-04-23
Also published as: CN113756131A; EP3919679B1

Abstract

The invention relates to a treatment section (150) of a production line (100) for producing a barrier coated fiber web, in particular a barrier coated carton board web, which treatment section comprises a coating section (60; 65) comprising an off-line melt coating polymer coater (60), advantageously extruder (60), and an unwinder (55) and a rewinder (70). The coating section (60; 65) comprises an off-line curtain dispersion coater (65). The unwinder (55) and/or the rewinder (70) are common to the off-line melt coating polymer coater (60) and to the off-line curtain dispersion coater (65).

Description

Technical field

The invention relates to producing a barrier coated fiber web. Especially the invention relates to a treatment section according to the features of the preamble part of claim 1.

Background

As known from the prior art in fiber web producing processes typically comprise an assembly formed by a number of apparatuses arranged consecutively in the process line. A typical production line comprises a head box, a wire section, and a press section as well as a subsequent drying section and a reel-up. The production and treatment line can further comprise other devices and/or sections for finishing the fiber web, for example, a calender, a sizer, a final-calender, a coating section. The production line also typically comprises at least one slitter-winder for forming customer rolls as well as a roll packaging apparatus or a sheet cutter. In this description and the following claims by fiber webs are meant for example a paper and board webs.
In production of fiber webs, for example of paper or board webs, sizing is used to alter the properties of a fiber web by adding sizing substances, for example starch. Sizing can be divided to internal sizing and surface sizing. In internal sizing the sizing agent is added to pulp in the wet end of the fiber web machine before forming. In surface sizing the sizing substance is added onto the surface of the fiber web directly or via a roll typically at the dry end of the fiber web machine but the sizing substance can be added onto the fiber web at other parts of the fiber web production line, also. The sizing of paper and board web typically utilize a separate sizer. In connection with the sizer different kinds of sizing technology are employed in prior art arrangements, for example pond sizing technology or film-transfer technology or spray sizing technology. Coated fiber web grades and coating are becoming more and more popular and thus the coating process and equipment have increasing demands imposed thereon. In coating, especially in pigment coating, at least one of the surfaces of a fiber web is formed with one or more layers of coating color (coating substance) at a coating station followed by drying. The process of coating can be divided in supplying the coating color onto the web surface, which is called the application of the coating color, as well as in the adjustment of final amount of coating color. The coating of paper and board web typically utilize a coating device - a coater. In connection with the coater different kinds of coating technology are employed in prior art arrangements, for example curtain coating, blade coating, spray coating or film transfer coating technology.
The barrier coated fiber web products i.e. barrier products are typically coated paper or board -based fiber web products which have one or more layers with barrier function such as water barrier, water vapor barrier, grease/oil/solvent barrier, gas and aroma -barrier. Thus these barrier layers are against the penetration of gases (odor, aroma, oxygen, nitrogen, carbon dioxide, water vapor etc.), against the penetration of fluids and solvents either polar (f. ex. water) or non-polar (f. ex. grease, oil), against the penetration of solids and contamination of particles (nano-particles, dust, fumes, dirt etc.) and of germs, bacteria, fungi etc., and against the penetration of radiation (electromagnetic, f. ex. visible light, IR, US, X-ray, "electro smog" et.) and of radioactivity. A barrier product may have one or more barrier layers with one or more different barrier functions.
Barrier coated fiber webs have been produced for example by applying melt coating polymer by extrusion onto the surface of the fiber web and/or by laminating onto the surface of the fiber web an aluminum foil by off-line melt coating polymer coaters, advantageously extruders. A disadvantage in extrusion coated barrier products is their poor pulping properties and thus poor recyclability. Application by dispersion coating off-line has also been used, in which binder for example latex with several different types of fillers and/or mineral pigments and/or additives is applied. The use of dispersion coating has been limited due to more expensive coating substances than typically used in extrusion coating. The coating has been dried after application in order to provide a fixed, continuous, non-porous coating with desired barrier properties onto the surface of the fiber web.
Most typically a barrier coated fiber web, for example for liquid packages, is produced in a fiber web production line by applying melt coating polymer onto the surface of the fiber web by an off-line melt coating polymer coater. Technically on-line melt coating polymer coating could be possible, but the disadvantages relating to poor pulping properties and thus poor recyclability of melt coating polymer coated fiber webs have so far proven the on-line melt coating polymer coating non-reasonable.
In production of barrier coated fiber webs one important factor is requirement of high hygienic level to prevent contamination of the barrier coated fiber web of the packaging applications having high hygienic requirements.
In patent publication EP3286378B1 is disclosed a method for manufacturing coated paperboard suitable for packaging paperboard applications, the method comprising coating a first surface of the paperboard web by applying a first coating composition in a precoating unit for forming a precoating layer comprising inorganic mineral pigment particles and least one binder for sealing the first surface of the paperboard web, weight of the precoating layer being less than 30 g/m<2> , and a second coating composition in form of an aqueous polymer dispersion in a curtain coating unit for forming at least one barrier coating layer having a weight less than 20 g/m<2> on top of the precoating layer, and a third coating composition comprising a polymer dispersion in the curtain coating unit for forming at least one heat sealable coating layer, having a weight less than 20 g/m<2> , on top of the barrier coating layer, whereby the second and third coating layers are applied simultaneously as aqueous dispersions without intermediate drying between the coating layers.
An object of the present invention is to create a treatment section of a production line for producing a barrier coated fiber web, in which problems and disadvantages of the treatment sections and methods known from prior art are eliminated or at least minimized.
Another object of the present invention is to create an improved treatment section of a production line for producing a barrier coated fiber web, especially in view of flexibility of production.

Summary

In order to achieve the above mentioned and those later presented the treatment section according to the invention is mainly characterized by the features of the characterizing part of claim 1. Further advantageous embodiments and features of the invention are disclosed in the dependent claims.
According to the invention the treatment section of a production line for producing a barrier coated fiber web, in particular a barrier coated carton board web, which treatment section comprises a coating section comprising at least one off-line melt coating polymer coater, advantageously extruder, and an unwinder and a rewinder, wherein the coating section comprises at least one off-line curtain dispersion coater and the unwinder and/or the rewinder are common to the at least one off-line melt coating polymer coater and to the at least one off-line curtain dispersion coater.
According to an advantageous feature of the invention the off-line curtain dispersion coater is a multilayer curtain dispersion coater for applying one or more coating substance layers onto one or both sides of the fiber web by curtain slots.
According to an advantageous feature of the invention the off-line curtain dispersion coater is formed of successive curtain dispersion coaters, each for one or more coating substance layers, for applying one or more coating substance layers onto one or both sides of the fiber web.
According to an advantageous feature of the invention the treatment section is configured to be an off-line treatment section of a production line for a barrier coated fiber web, which production line comprises on-line sections for producing an uncoated fiber web.
According to an advantageous feature of the invention the production line comprises a head box, a wire section, a press section, a drying section and, a reel-up.
According to an advantageous feature of the invention the treatment section comprises a sizer and a calender.
According to an advantageous aspect of the invention the treatment section and the treatment method for producing a barrier coated fiber web have the combination of the off-line melt coating polymer coating and the off-line dispersion curtain coating.
According to an aspect of the invention the treatment section comprises more than one an off-line melt coating polymer coaters and more than one off-line melt coating polymer coaters.
By the treatment section of a production line for producing a barrier coated fiber web and its advantageous features many advantages are achieved: Flexibility of the production is achieved as both melt coating polymer coated fiber webs and dispersion coated fiber webs can be produced by the same production line. The coating layers can be applied on one side of the fiber web or on both sides of the fiber web and depending on the need both sides of the fiber web can be coated by melt coating polymer coating or by dispersion coating or one side of the fiber web can be coated by melt coating polymer coating and the other side of the fiber web by dispersion coating. Additionally, the off-line dispersion curtain coater provides the possibility of coating the fiber web on one or both sides by pigment coating, which even makes possible to produce new variety of fiber web grades. Further the curtain coating method, especially by a so-called cabinet coater, inside of which there is typically no need to enter, is very hygienic compared to other typical coating methods, as splashes and dripping of coating substance in this method is substantially non-existent. The present invention thus provides for significant advantages in view of producing variety of different grades of fiber webs, which remarkably increases the total efficiency of the fiber web production line.

Brief description of the drawings

In the following the invention and its advantages are explained in greater detail below in the sense of example and with reference to accompanying drawing, where

Figure 1 shows schematically one advantageous example of a production line for barrier coated fiber webs.
Figure 2 shows schematically alternatives of advantageous coating systems in an off-line treatment section according to the invention.

Detailed description

During the course of the following description like numbers and signs will be used to identify like elements according to the different views which illustrate the invention and its advantageous examples. In the figures some repetitive reference signs may have been omitted for clarity reasons.
In the examples of figures 1 and 2 the production line of a barrier coated fiber web product is shown very schematically and it is well understood by one skilled in the art that the actual production line for the barrier coated fiber web product comprises several components, parts and devices which can be constructed in various ways known as such to one skilled in the art. It should also be noted that the invention can be utilized both in connection with production of one-sided fiber web products and in connection with two-sided fiber web products and for many types of barrier coated fiber web products (barrier products). It should also be noted that the treatment section may comprise more than one an off-line melt coating polymer coaters and more than one off-line melt coating polymer coater as well as other related sections, devices, and equipment.
In the example of figure 1 the production line 100 comprises a head box 10, a wire section (i.e. forming section) 15 and a press section 20 as well as a subsequent drying section 25, a sizer 30 and an optional calender 40 and a reel-up 45. The off-line treatment section 150 of the production line 100 comprises an unwinder 55, a coating section 60;65, a rewinder 70 and a slitter-winder 75.
The on-line part of the production line 100 thus comprises the head box 10, the wire section (i.e. forming section) 15 and the press section 20 as well as a subsequent drying section 25, the sizer 30 and the optional calender 40 and the reel-up 45 and a parent roll 50 of uncoated fiber web is produced. The parent roll 50 of the uncoated fiber web is transferred to the off-line treatment section 150 comprising the unwinder 55, the coating section 60;65, the rewinder 70 and the slitter-winder 75 and customer rolls 85 of barrier coated fiber web is produced. Depending on the size of the parent roll 50 produced in the on-line part of the production line 100, of the parent roll 50 smaller size rolls may be produced in an intermediate slitter-winder (not shown) before transferring the rolls to the off-line treatment section 150 for production of the customer rolls 85 of barrier coated fiber web.
In the example of figure 1 after the sizer 30 drying equipment 35 is located to dry the fiber web. Also, the coating section 60;65 of the treatment section 150 comprises drying and/or cooling equipment (not shown) to dry/cool the fiber web before reeling the fiber web in the rewinder 70. Optional cooling devices 80 are in this example located before the sizer 30 and the calender 40 and the reel-up 45 and the rewinder 70. The sizer 30 can be located in any other part or section of the production line before the coating section 60;65. The sizer 30 is advantageously a pond size press, a film size press, a spray sizer or very advantageously a nip sizer with curtain applicator(s) or a foam applicator(s).
The coating section 60;65 of the off-line treatment section 150 comprises at least one melt coating polymer coater 60, advantageously extruder 60, and at least one multilayer curtain dispersion coater 65 with one or more curtain slots for applying one or more coating substance layers onto the fiber web to provide the barrier coating layer/-s onto one or both sides of the fiber web. The curtain dispersion coater 65 can also be formed of successive curtain dispersion coaters, each for one or more coating substance layers.
In the treatment section 150 of this example the unwinder 55 and the rewinder 70 are common to the off-line melt coating polymer coater 60 and to the off-line curtain dispersion coater 65. At least, the unwinder 55 or the rewinder 70 are common to the off-line melt coating polymer coater 60 and to the off-line curtain dispersion coater 65.
In production of the fiber web from the head box 10 pulp is fed onto the wire section (i.e. forming section) 15, in which water is removed from the pulp by water removal means. In the press section 20 water is further removed by pressing the fiber web in press nips and/ or in shoe - or belt nips. In the subsequent drying section 25 the fiber web is dried, typically by contact drying by leading the fiber web to run in contact over heated surfaces of drying cylinders. After the drying section 25 in the sizer 30 sizing substance is applied onto the fiber web and thereafter the fiber web is typically dried by following drying equipment 35. Thereafter the fiber web may be calendered in the optional calender 40. In the reel-up 45 the fiber web is reeled into the parent roll 50 of uncoated fiber web.
Depending on the size of the parent roll 50 produced in the on-line part of the production line 100, of the parent roll 50 smaller size rolls may be produced in an intermediate slitter-winder (not shown) before transferring the rolls to the off-line treatment section 150 for production of the customer rolls 85 of barrier coated fiber web.
The parent roll 50 of uncoated fiber web is transferred to the off-line treatment section 150 and is first unwound in the unwinder 55. Then, at least one coating layer is applied onto the fiber web in the coating section 60;65 in order to provide the barrier coating. After coating the fiber web is, if needed, dried by drying equipment (not shown), typically at least in the beginning of this drying by contactless drying equipment. The fiber web may also be cooled by cooling equipment (not shown) after the coating. In the rewinder 70 the barrier coated fiber web is reeled into the parent roll, which is unwound in an unwinder of the slitter-winder 75 ja then slit into partial webs in a slitter, which are wound to customer rolls 85 in the winder. T
Figure 2 shows schematically some alternatives of advantageous coating systems in the off-line treatment section 150. In this example the coating section 60;65 of the off-line treatment section 150 comprises an unwinder 55 and a rewinder 70, an off-line melt coating polymer coater 60, advantageously extruder 60, and an off-line curtain dispersion coater 65, which comprises a curtain dispersion coater 65 for applying one or more coating substance layers onto the fiber web. The curtain dispersion coater 65 is in the alternative of the upper row of figure 2 a multilayer curtain dispersion coater for applying one or more coating substance layers by one or more curtain slots 651, 652, 653 to provide the barrier coating layer/-s onto one or both sides of the fiber web. The curtain dispersion coater 65 can also be formed of successive curtain coaters 65F, 65S, 65T, each for applying one or more coating substance layers i.e. with one or more curtain slots. In the treatment section 150 of the example the unwinder 55 and the rewinder 70 are common to the off-line melt coating polymer coater 60 and to the off-line curtain dispersion coater. At least, the unwinder 55 or the rewinder 70 are common to the off-line melt coating polymer coater 60 and to the off-line curtain dispersion coater 65.
The alternatives of the advantageous coating systems by the melt coating polymer coater 60, advantageously extruder 60, and the curtain dispersion coater 65 are denoted in the figure 2 by letters A, B, C, D. The parent roll 50 of uncoated fiber web is transferred from the on-line part of the production line 100 and unwound in the unwinder 55 before the barrier coating. Depending on the size of the parent roll 50 produced in the on-line part of the production line 100, of the parent roll 50 smaller size rolls may be produced in an intermediate slitter-winder (not shown) before transferring the rolls to the off-line treatment section 150 for production of the customer rolls 85 of barrier coated fiber web.
In the alternative A, presented in the upper row of figure 2, the in the unwinder 55 unwound, uncoated fiber web is coated only on one side, first by a curtain slot 651; 652; 653 of the curtain dispersion coater 65 a dispersion coating layer is applied as a first coating layer and thereafter a melt coating polymer coating layer is applied as a second coating layer by the melt coating polymer coater, advantageously extruder 60. Then, the barrier coated fiber web is wound in the rewinder 70.
In the alternative B, presented in the lower row of figure 2 at left, the in the unwinder 55 unwound, uncoated fiber web is coated on both sides, first by the curtain coater 65F of the curtain dispersion coater 65 a dispersion coating layer is applied as a first coating layer on one side of the fiber web, then by the curtain coater 65S of the curtain dispersion coater 65 a dispersion coating layer is applied as a second coating layer on the one side of the fiber web and thereafter by the curtain slot 65T of the curtain dispersion coater 65 a dispersion coating layer is applied as a first coating layer on other side of the fiber web. Then, the barrier coated fiber web is wound in the rewinder 70.
In the alternative C, presented in the lower row of figure 2 at left, the in the unwinder 55 unwound, uncoated fiber web is coated on both sides, first by the curtain coater 65F of the curtain dispersion coater 65 a dispersion coating layer is applied as a first coating layer on one side of the fiber web, then by the curtain coater 65S of the curtain dispersion coater 65 a dispersion coating layer is applied as a second coating layer on the one side of the fiber web and thereafter by the curtain coater 65T of the curtain dispersion coater 65 a dispersion coating layer is applied as a first coating layer on other side of the fiber web and thereafter a melt coating polymer coating layer is applied by the melt coating polymer coater 60, advantageously extruder 60, as a second coating layer on the other side of the fiber web. Then, the barrier coated fiber web is wound in the rewinder 70.
In the alternative D, presented in the lower row of figure 2, the in the unwinder 55 unwound, uncoated fiber web is coated only on one side, a melt coating polymer coating layer is applied as a coating layer by the melt coating polymer coater 60, advantageously extruder 60. Then, the barrier coated fiber web is wound in the rewinder 70.
It is apparent that multiple alternatives in addition to those presented above are possible both in connection with production of one-sided barrier fiber web products and in connection with two-sided barrier fiber web products by the off-line treatment section 150 comprising the melt coating polymer coater 60, advantageously extruder 60, and the curtain dispersion coater 65.
In the description in the foregoing, although some functions and elements have been described with reference to certain features and examples, those functions and elements may be performable by other features and examples whether described or not. Although features have been described with reference to certain embodiments or examples, those features may also be present in other embodiments or examples whether described or not.
Above only some advantageous examples of the inventions have been described to which examples the invention is not to be narrowly limited and many modifications and alterations are possible within the invention.

Claims

Treatment section (150) of a production line (100) for producing a barrier coated fiber web, in particular a barrier coated carton board web, which treatment section comprises a coating section (60; 65) comprising at least one off-line melt coating polymer coater (60), advantageously extruder (60), and an unwinder (55) and a rewinder (70), characterized in that the coating section (60; 65) comprises at least one off-line curtain dispersion coater (65) and that the unwinder (55) and/or the rewinder (70) are common to the at least one off-line melt coating polymer coater (60) and to the at least one off-line curtain dispersion coater (65).
Treatment section according to claim 1, characterized in that the off-line curtain dispersion coater (65) is a multilayer curtain dispersion coater (65) for applying one or more coating substance layers onto one or both sides of the fiber web by curtain slots (651, 652, 653).
Treatment section according to claim 1, characterized in that the off-line curtain dispersion coater (65) is formed of successive curtain coaters (65F, 65S, 65T), each for one or more coating substance layers, for applying one or more coating substance layers onto one or both sides of the fiber web.
Treatment section according to any of the previous claims, characterized in that the treatment section (150) is configured to be an off-line treatment section (150) of a production line (100) for a barrier coated fiber web, which production line (100) comprises on-line sections for producing an uncoated fiber web.
Treatment section according to claim 4, characterized in that the production line (100) comprises a head box (10), a wire section (15), a press section (20), a drying section (25) and a reel-up (45).
Treatment section according to claim 5, characterized in that the treatment section comprises a sizer (30) and a calender (40).