FI128753B

FI128753B - Method of treating a fiber web and a treatment system for treatment of a fiber web

Info

Publication number: FI128753B
Application number: FI20185739A
Authority: FI
Inventors: Tapio Pitkäniemi; Jani Hakola
Original assignee: Valmet Technologies Oy
Priority date: 2018-09-05
Filing date: 2018-09-05
Publication date: 2020-11-30
Also published as: AT521651A2; DE102019122371A1; AT521651A3; AT521651B1; FI20185739A1

Abstract

The invention relates to a method of treating a fiber web, in which method the fiber web (W) is coated by curtain coating or sized by curtain sizing in a coater / sizer com-prising a curtain coating / sizing device (10) with at least one rotatable coating / sizing roll (20) by out-board curtain coating / sizing method, in which the curtain (C) of coating color / sizing agent falls as a curtain wider than width of the fiber web (W) to be coated / sized as the curtain (C) falls downwards. Each end of the curtain (C) is guided by an edge guide (18) and that the curtain (C) has width (LC) wider than length (L20) of the coating / sizing roll (20). In the method the coating color / sizing agent layer on the end of the edge areas (25) of the coating color / sizing agent on the surface of the coating / sizing roll (20) is split by a corner-effect of an end corner of the coating / sizing roll (20). The invention also relates to a treatment system for treatment of a fiber web, which comprises a curtain coater or sizer comprising at least one coating / sizing roll (20) and a curtain coating or sizing device (10) comprising a nozzle opening / nozzle openings providing a coating / sizing curtain (C) wider than width of the fiber web (W) to be coated / sized. The treatment system further comprises edge guides (18) located at each end of the curtain (C) and that in the curtain device (10) the nozzle opening/s are located in longitudinal direction of the curtain device (10), i.e. in cross-direction of a fiber web (W) to be coated / sized such, that the curtain (C) has width (LC) wider than length (L20) of the coating / sizing roll (20) and an end-corner of the coating / sizing roll (20) is provided to split by a corner-effect the coating color / sizing agent layer on the end of the edge areas (25) of the coating color / sizing agent on the surface of the coating / sizing roll (20). (Figure

Description

Method of treating a fiber web and a treatment system for treatment of a fi- ber web

In general, the present invention relates to treating of fiber webs in a fiber web production line, in particular, the present invention relates to a curtain sizing or coating method and to a curtain sizing or coating method device. More especially the present invention relates to a method according to preamble part of the inde- pendent method claim and to a treatment system according to preamble part of the independent treatment system claim.

In this description and the following claims by fiber webs are meant for example paper and board webs.

Fiber webs, such as paper and board webs are available in a wide variety of types and can be divided according to basis weight in two grades: papers with a single ply and a basis weight of 25-300 g/m? and boards manufactured in multi-ply tech- nology and having a basis weight of 150-600 m/m?. It should be noted that the borderline between paper and board is flexible since board grades with lightest basis weights are lighter than the heaviest paper grades. Generally speaking, pa- per is used for printing and board for packaging.

The subsequent descriptions are examples of values presently applied for fiber webs, and there may be considerable fluctuations from the disclosed values. The descriptions are mainly based on the source publication Papermaking Science and

Technology, section Papermaking Part 3, edited by Rautiainen, P., and published by Paper Engineers’ Association, Helsinki 2009, 404 pages.

Mechanical-pulp based, i.e. wood-containing printing papers include newsprint,

N uncoated magazine and coated magazine paper.

N

= 25 Today's newsprint furnishes mostly contain between 80 and 100 % deinked pulp 2 (DIP). The rest of the furnish is mechanical pulp (typically TMP). However, there is

I also newsprint made of 100 % mechanical fiber furnishes. DIP based newsprint = may contain up to 20 % filler. The filler content of a virgin-fiber based newsprint

O furnish is about 8 %.

LO

= 30 General values for CSWO newsprint can be regarded as follows: basis weight 40-

N 48.8 g/m?, PPS s10 roughness (SCAN-P 76-95) 4.0-4.5 um, Bendtsen roughness (SCAN-P21:67) 150 ml/min, density 600-750 kg/m?, brightness (ISO 2470:1999) 58-59 %, and opacity (ISO 2470:1998) 92-95%.

Uncoated magazine paper (SC-supercalendered) grades usually contain 50 % - 75 % mechanical pulp, 5 % - 25 % chemical pulp, and 10 % - 35 % filler. The pa- per may also contain DIP. Typical values for calendered SC paper (containing e.g.

SC-C, SC-B, and SC-A/A+) include basis weight 40-60 g/m?, ash content (SCAN-P 5:63) 0-35%, Hunter gloss (ISO/DIS 8254/1) <20-50%, PPS s10 roughness (SCAN-P 76:95) 1.0-2.5 um, density 700-1250 kg/m3, brightness (ISO 2470:1999) 62-75%, and opacity (ISO 2470:1998) 90-95%.

Coated mechanical papers include for example MFC (machine finished coated),

LWC (lightweight coated), MWC (medium weight coated), and HWC (heavy weight coated) grades. Coated mechanical papers usually contain 45 % -75 % mechani- cal or recycled fiber and 25 % - 55 % chemical pulp. Semi chemical pulps are typi- cal in LWC paper grades made in the Far East. The filler content is about 5 % -10 %. The grammage is typically in the range 40-80 g/m2.

General values for LWC paper can be regarded as follows: basis weight 40-70 g/m? Hunter gloss 50-65%, PPS S10 roughness 1.0-1.5 um (offset) and 0.6-1.0 um (roto), density 1100-1250 kg/m?, brightness 70-75%, and opacity 89-94%.

General values for MFC paper (machine finished coated) can be regarded as fol- lows: basis weight 48-70 g/m? Hunter gloss 25-40%, PPS S10 roughness 2.2-2.8 um, density 900-950 kg/ m3, brightness 70-75%, and opacity 91-95%.

General values for MWC paper (medium weight coated) can be regarded as fol- lows: basis weight 70-90 g/ m?, Hunter gloss 65-70%, PPS S10 roughness 0.6-1.0 um, density 1150-1250 kg/ m3, brightness 70-75%, and opacity 89-94%.

Wood free paper is divided into two segments: uncoated and coated. Convention-

N ally, the furnish of wood free papers consists of bleached chemical pulp, with less = 25 than 10 % mechanical pulp. 2 Typical values are for uncoated WFU Copy paper: grammage 70-80 g/m?

I Bendtsen roughness 150-250 ml/min and bulk > 1.3 cm3/g; for uncoated offset = paper: grammage 60-240 g/m? Bendtsen roughness 100-200 ml/min and bulk 1.2-

O 1.3 cm3/g; and for color copy paper: grammage 100 g/m?, Bendtsen roughness < o 30 50 ml/min and bulk 1.1 cm3/g.

O

N In coated pulp-based printing papers (WFC), the amounts of coating vary widely in accordance with reguirements and intended application. The following are typical values for once- and twice-coated, pulp-based printing paper: once-coated basis weight 90 g/ m?, Hunter gloss 65-80%, PPS s10 roughness 0.75-1.1 um, bright- ness 80-88%, and opacity 91-94%, and twice-coated basis weight 130 g/ m?,

Hunter gloss 70-80%, PPS S10 roughness 0.65-0.95 um, brightness 83-90%, and opacity 95-97%.

Containerboard includes both linerboard and corrugating medium. Liners are di- vided according to their furnish base into Kraft liner, recycled liner and white top liner. Liners are typically 1- to 3-ply boards with grammage varying in the range 100-300 g/m?.

Linerboards are generally uncoated, but the production of coated white-top liner is increasing to meet higher demands for printability.

The main cartonboard grades are folding boxboard (FBB), white-lined chipboard (WLC), solid bleached board (SBS) and liguid packaging board (LPB). In general, these grades are typically used for different kinds of packaging of consumer goods. Carton board grades vary from one- up to five-ply boards (150-400 g/m*).

The top side is usually coated with from one to three layers (20-40 g/m?); the back side has less coating or no coating at all. There is a wide range of different guality data for the same board grade. FBB has the highest bulk thanks to the mechanical or chemi mechanical pulp used in the middle layer of the base board. The middle layer of WLC consists mainly of recycled fiber, whereas SBS is made from chemi- cal pulp, exclusively.

FBB's bulk typically is between 1.1-1.9 cm? g whereas WLC is on range 1.1-1.6 cm3/g and SBS 0.95-1.3 cm?/g. The PPS-s10-smoothess is respectively for FBB between 0.8 — 2.1 um, for WLC 1.3- 4.5 um and for SBS 0.7 — 2.1 um.

N Release paper is used in label base paper in various end-use applications, such

N 25 as food packaging and office labels. The most common release paper in Europe is - supercalendered glassine paper coated with silicone to provide good release 3 properties. = = Typical values for supercalendered release papers are basis weight 60 - 95 g/m?,

O caliper 55-79 um, IGT 12-15 cm, Cobb Unger for dense side 0.9-1.6 g/m? and for o 30 open side 1.2-2.5 g/m.

O

N Coated label paper is used as face paper for release, but also for coated backing paper and flexible packings. Coated label paper has a grammage of 60-120 g/m? and is typically sized or pre-coated with a sizer and single-blade coated on one side. Some typical paper properties for coated and calendered label paper are ba- sis weight 50-100 g/m? Hunter gloss 70-85%, PPS s10 roughness 0.6-1.0 um,

Bekk smoothness 1500-2000 s and caliper 45-90 um.

The fiber webs are produced in a fiber web producing process. As known from the prior art in fiber web producing processes typically comprise an assembly formed by a number of apparatus arranged consecutively in the process line. A typical production and treatment 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 pre-calender, a sizer, a final-calender, a coating section.

The production and treatment line also typically comprises at least one slitter- winder for forming customer rolls as well as a roll packaging apparatus.

In production of fiber webs, for example in production of paper or board webs, siz- ing is used to alter the properties of a fiber web by adding sizing agents, for exam- ple starch or other sizing agents. Sizing can be divided to internal sizing and sur- face 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 agent is added onto the surface of the fiber web typically at the dry end of the fiber web machine. Sur- face sizing is used in production of many fiber web grades, for example of uncoat- ed fine papers and of several board grades. Sizing is used in order to improve pa- per web properties, in particular water resistance, water absorption properties, strength, internal strength and bending stiffness. In addition, runnability as well as dusting tendency can be affected favorably.

In production of fiber webs, for example in production of paper or board webs, in

S 25 coating, especially in pigment coating, the surface of a fiber web is formed with a

N layer of coating color at a coating station (a coater) followed by drying. The for- = mation of a coating color can be divided in supplying the coating color onto the 2 web surface, which is called the application of the coating color, as well as in the

I adjustment of final amount of coating color. a 3 30 One important recently developed sizing or coating technique is curtain sizing or 5 coating, which is suitable to size or to coat paper and board webs. By curtain siz-

D ing or coating good coverage of sizing agents or coating color on the fiber web

N surface to be sized or coated is achieved.

In curtain sizing or coating two main types of curtain sizing or coating devices are used, namely curtain sizing or coating devices with slot-fed and curtain sizing or coating devices with slide-fed. In the slide fed curtain sizing or coating devices, sizing agents or coating color is fed by means of a nozzle assembly onto an in- 5 clined plane and the sizing agents or coating color flows down towards an edge of the plane constituting a nozzle lip and the curtain is formed as the sizing agents or coating color falls off the nozzle lip onto the web. In the slot-fed curtain sizing or coating devices sizing agents or coating color is pumped through a distribution chamber into a narrow vertical slot and the curtain is formed at its lip and falls onto the web Sizing agents or coating color can be applied in one or more curtain lay- ers.

Typically, two different methods are used to control width of the curtain. One is to feed the curtain wider than width of the fiber web to be coated/sized and then the width is allowed freely narrow in cross direction of the web as the curtain falls downwards towards the fiber web. This method is called as out-board method. The other, called as in-board method, is to feed the curtain narrower than the width of the fiber web to be coated, and the width is reguired to maintain uniform as the curtain falls downwards towards the fiber web. The curtain is maintained at re- quired width by means of edge guides which are located along each edge of the feeding slot / the nozzle lip. An edge guide typically comprises a flow surface for guiding the edge of the sizing or coating curtain, a lubrication liquid (typically wa- ter) supply(s) onto edge guide, a collecting lip and a suction channel for collecting and removing edge area sizing agents or coating color and lubrication liquid.

One disadvantage, when using edge guides, is that a small accumulation of sizing agents or coating color accumulates at edge area of the sizing agents or coating

N color layer, which typically is evened by using air flow blows to even out the accu-

N mulated sizing agents or coating color. But still even a small extra amount of sizing - agents or coating color at the edge of the curtain causes droplet formation and 3 splashing at the edge areas. The surface of the sizing or coating roll is curved and

E 30 thus the centrifugal force causes that the splashing begins directly at the end of o the edge guide, when the sizing agents or coating color reaches the surface of the

S sizing or coating roll and thus the air flow blows do not prevent the splashing of the 2 sizing or coating effect. Sometimes this has been tried to solve by using suction at

N the end of the edge guide but functions properly only when the edge guide is lo- cated at a distance from the sizing or coating roll and a deckle is needed. But there still remains a small free drop distance during which an extra amount of the sizing agents or coating color at the edge of the curtain may form droplets and thus the disadvantages and problems of droplet formation and splashing remain to be solved.

One disadvantage, when using the out-board method, relates to the edge area of the coating or sizing roll not covered by the fiber web to be coated or sized, which is to be kept clean such that the coating color or sizing agent falling from the cur- tain to these edge areas does not create droplets or splashing nor cause contami- nation damages or disturbances in the coater or sizer nor in following section/-s of the fiber web production and treatment process.

In publication WO9001179A1 is disclosed apparatus for curtain coating a support with at least one layer of coating liquid. The apparatus includes conveying means, including a coating roller, for moving a support along a path. Hopper means are provided for forming at least one layer of coating liquid into a free-falling curtain which intercepts, and extends transversely of, the path of the support. The curtain — is wider than the desired width of the coating to be formed on the support. The ap- paratus further includes curtain-severing means for intercepting and diverting the margins of the curtain. Such curtain-severing means includes a blade disposed in a plane approximately parallel to the plane of the support where the composition impinges on it. The blade is disposed over the path upstream of the plane of the curtain, extends through the plane of the curtain and is disposed outboard of the path of the support downstream of the plane of the curtain. Also means are pro- vided for passing purging liquid over the upper face of the blade for carrying inter- cepted material in the curtain outboard of the path of the support. In this known ar- rangement the curtain is split above the roller near edges, which may cause ac- cumulation of the coating liquid on the edge areas of the roller and/or splashing of

N the coating liguid, which disadvantages would even emphasize with increasing

N running speeds. Also, in this know arrangement width of the coating layer is ad- - justed by adjusting width of the curtain.

O z An object of the invention is to create a method of treating a fiber web and a = 30 treatment system for treatment of a fiber web, in particular a curtain sizing or coat-

O ing method and device, in which the disadvantages of the prior art are eliminated o or at least minimized.

N

A particular object is to create a method of treating a fiber web and a treatment system for treatment of a fiber web, in particular a curtain sizing or coating method and device, in which the disadvantages and problems relating to edge guides and out-board curtain coating or sizing method, explained above, are eliminated or at least minimized.

A particular object is to create a method of treating a fiber web and a treatment system for treatment of a fiber web, in particular a curtain sizing or coating meth- od and device, in which accumulation of coating color or sizing agent and splash- ing of the same is eliminated and/or minimized.

To achieve the objects mentioned above and later the method according to the in- vention is mainly characterized by the features of the characterizing part of claim 1.

The treatment system for treatment of a fiber web according to the invention is mainly characterized by the features of the characterizing part of claim 5.

Advantageous features and embodiments of the invention are defined in the de- pendent claims.

According to the invention in the method of treating a fiber web the fiber web is coated by curtain coating or sized by curtain sizing in a coater / sizer comprising a curtain coating / sizing device with at least one rotatable coating / sizing roll by out- board curtain coating / sizing method, in which the curtain of coating color / sizing agent falls as a curtain wider than width of the fiber web to be coated / sized as the curtain falls downwards and each end of the curtain is guided by an edge guide, wherein the curtain has width wider than length of the coating / sizing roll and the coating color / sizing agent layer on the end of the edge areas of the coating color / sizing agent on the surface of the coating / sizing roll is split by a corner-effect of > an end corner of the coating / sizing roll.

QA

N According to the invention the treatment system for treatment of a fiber web com- = 25 prises a curtain coater or sizer comprising at least one coating / sizing roll and a 2 curtain coating or sizing device comprising a nozzle opening / nozzle openings

I providing a coating / sizing curtain wider than width of the fiber web to be coated / = sized, which treatment system further comprises edge guides located at each end

O of the curtain wherein the curtain device the nozzle opening/s are located in longi-

O 30 tudinal direction of the curtain device, i.e. in cross-direction of a fiber web to be > coated / sized such, that the curtain has width wider than length of the coating / sizing roll and an end-corner of the coating / sizing roll is provided to split by a cor- ner-effect the coating color / sizing agent layer on the end of the edge areas of the coating color / sizing agent on the surface of the coating / sizing roll.

In the method and in the system in accordance with the invention the corner-effect that splits the curtain forming the coating color / sizing agent layer i.e. provides the splitting effect is created by the corner formed between the end surface and the curved surface of the roll at each of the ends of the roll when the curtain reaches the curved surface of the roll. In a way the corner divides i.e. splits the curtain to two parts: one part forming the coating color / sizing agent layer onto the curved surface of the roll and the fiber web and one part over the corner and to be dis- charged.

According to one advantageous feature of the invention by centrifugal forces cre- ated by the rotating coating / sizing roll splitting of the coating color / sizing agent layer on the end of the edge areas of the coating color / sizing agent on the sur- face of the coating / sizing roll is enhanced.

According to one advantageous feature of the invention the coating color / sizing agent falling in the curtain at the areas over the length of the coating / sizing roll, ie. extra, excessive coating color / sizing agent, is collected at each end of the coating / sizing roll into deckles arranged correspondingly at or in immediate vicini- ty of each end of the coating / sizing roll.

According to one advantageous feature of the invention longitudinal edge areas of the coating / sizing roll not covered by the fiber web to be coated / sized are cleaned by a cleaning system comprising a doctor.

According to one advantageous feature of the invention at each end of the coating / sizing roll deckles are arranged at or in immediate vicinity of each end of the coating / sizing roll to collect the coating color / sizing agent falling in the curtain at o the areas over the length of the coating / sizing roll, i.e. extra, excessive coating

O 25 — color / sizing agent. - According to one advantageous feature of the invention the treatment system fur- 3 ther comprises cleaning systems located at longitudinal edge areas of the coating /

E sizing roll not covered by the fiber web to be coated / sized. According to one ad- o vantageous feature of the invention the cleaning system comprises a doctor.

O

15 30 According to one, in particular advantageous, aspect of the invention an out-board > method-type curtain coating / sizing method is used as a new extended version of the out-board method and in combination thereto an edge guide system is provid- ed. The width of the curtain in addition to the curtain being wider than width of the fiber web to be coated/sized is wider than the length of the coating / sizing roll. To collect the coating color / sizing agent falling in the curtain at the areas over the length of the coating / sizing roll a deckle is arranged at or in immediate vicinity of the end of the coating / sizing roll at each end of the coating / sizing roll. Also, at each end of the curtain an edge guide is arranged, which guides the edge of the curtain and the coating color / sizing agent falling in the curtain at the areas over the length of the coating / sizing roll to the deckle. A small gap with controlled leakage may be provided between the deckle and the end of the coating / sizing roll with advantageously additional doctor for cleaning the end of the coating / siz- ing roll of the possible coating color / sizing agent. The end of the edge guide is lo- cated over or in the deckle, advantageously below surface level of the coating col- or / sizing agent collected into the deckle. The system may comprise means to guide the coating color / sizing agent from the deckle to disposal or for further use.

The coating color / sizing agent falling with the curtain onto the edge areas of the coating / sizing roll not covered by the fiber web to be coated / sized is advanta- geously removed by doctor.

In the method and in the system according to the invention either one or both sides of the fiber web are treated.

By the invention and its advantageous aspects and features many advantages are achieved as no accumulation of coating color / sizing agent nor splashing there of occurs due the splitting effect of the end corner of the coating / sizing roll splitting the coating color / sizing agent layer on the end of the edge areas of the coating color / sizing agent on the surface of the coating / sizing roll and guides the extra, excessive coating color / sizing agent off the coating /sizing roll and to the deckle.

Additionally, in cleaning of the edge guides cleaning liquid amount does not need to be limited but instead ample amounts of cleaning liquid can be used. Further,

N the width of the curtain is adjusted by the edge guides and is thus easily accom- = plished. 2 In the following the invention is further explained in detail with reference to the ac-

I companying drawing in which: a 3 30 Infigure 1 is schematically shown an advantageous example of the treatment sys- 5 tem in a sizer application according to the invention,

S In figures 2A-2C is schematically shown examples of sizer layouts with an advan- tageous example of the invention,

In figure 3 is schematically shown a part view of an example of an end part of a sizer roll in an advantageous example of the invention and

In figures 4A-4B is schematically shown examples of controlling surface level of sizing agent level in a deckle according to advantageous features of the invention.

In the following description same reference signs designate for respective compo- nents etc. unless otherwise mentioned and it should be understood that the exam- ples are susceptible of modification in order to adapt to different usages and condi- tions. In the description in the following, although some functions have been de- scribed with reference to certain features, those functions may be performable by other features 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. Below the invention has been described by referring to some advantageous examples only to which the invention is not to be narrowly limited. In particular the invention has been described below in view examples relating to curtain sizing of a fiber web and it should especially be noted that the examples are as well applicable in cur- tain coating of a fiber web. Additionally, it should be noted that corresponding sys- tem and method is used at each end of the curtain at each end of the sizing roll and in many of the examples the invention is described only in view of one end of the sizing roll. Many modifications and alterations are possible within the inventive idea.

In figure 1 is shown an example, in which an out-board method-type curtain sizing method is used as an extended version of the out-board method and in combina- tion thereto edge guides 18 (figs. 2A-2C & 3) are provided at each end of the siz-

S 25 ing curtain C. In the figure a curtain sizing device 10 is located above a sizing roll

N 20. A sizing curtain C is formed by the curtain sizing device 10 by its nozzle open- = ing/-s (not shown). The curtain, the sizing curtain C falls thus down onto the sizing 2 roll 20. Width LC of the curtain C in addition to that the curtain C being wider than

I width LW of the fiber web W to be sized, it is wider than the length L20 of a sizing = 30 roll 20. Thus, in the curtain sizing device 10 the nozzle opening/s are located in

O longitudinal direction of the device 10, i.e. in cross-direction of a fiber web W to be < sized, such that desired width of the curtain C is achieved. To collect the sizing > agent falling in the curtain C at the areas over the length L20 of the sizing roll 20 at each end of the sizing roll 20 deckles 15 (figs. 2A-4B) are arranged, correspond- ingly at or in immediate vicinity of the end of the sizing roll 20. Also, at each end of the curtain C the edge guides 18 are arranged, which guide the edge of the curtain

C and the sizing agent falling in the curtain C at the areas over the length L20 of the sizing roll 20 to the deckle 15. The edge areas 25 of the sizing roll 20 are pro- vided with advantageously additional doctor 17 (fig. 2A-2B) and/or washing means for cleaning the end of the sizing roll 20 of the possible sizing agent. The end of the edge guide 18 is located over or in the deckle 15, advantageously below sur- face level of the sizing agent collected into the deckle 15. The system may com- prise means to guide the sizing agent from the deckle 15 to disposal or for further use, for example an outlet 35 (figs. 4A-4B). The sizing agent falling with the curtain

C onto the edge areas 25 of the sizing roll 20 not covered by the fiber web W to be sized is advantageously cleaned by a cleaning system, for example removed by a doctor 17 (figs. 2A-2C).

In figures 2A-2C is shown examples of sizer layouts comprising a curtain sizing device 10 creating a curtain for sizing a fiber web W via a sizing roll 20. In the ex- amples of figures 2A-2B indirect sizing is used and the curtain falls onto surface of the rotating sizing roll 20 and as the sizing roll 20 rotates to a sizing nip formed be- tween two sizing rolls 20, 21; the sizing roll 20 with the curtain sizing device 10 above it and its counter sizing roll 21. In the example of figure 2C direct sizing is used and the curtain falls directly onto the fiber web W on the run of the fiber web

W over the sizing roll 20. At each of the edges of the curtain an edge guide 18 is located for guiding the extra, excessive sizing agent of the edge parts of the cur- tain not falling onto the fiber web W a deckle 15 for collecting the extra, excessive sizing agent. In the examples of figures 2A-2B the fiber web W to be sized is guid- ed to the sizing nip formed between the two sizing rolls 20, 21. In these examples the fiber web W is to be sized one-sidedly and thus the curtain sizing device 10, the edge guides 18 and the deckles 15 are located only in connection with one 20 o of the sizing rolls 20,21 and this sizing roll 20 is also provided with a doctor 17 for

O cleaning an edge area 25 (figs. 1 & 3) of the curved surface of the sizing roll 20 not — covered by the fiber web W to be sized. But the examples are as well applicable

A when the fiber web W is to be sized on both sides and thus in connection with both 7 30 sizing rolls 21,22. In the example of figure 2A the fiber web W has a downward run = in direction S and in the example of figure 2B the fiber web W has an upward run 3 in direction S. In figure 2C the fiber web W runs over the sizing roll 20 in direction 5 S.

N In figure 3 is shown a part view of an example of an end part of a sizer roll 20, in which an out-board method-type curtain sizing method is used as an extended version of the out-board method and in combination thereto an edge guide 18 is provided. The width LC (fig. 1) of the curtain C in addition to that the curtain C be- ing wider than width LW (fig. 1) of the fiber web W to be sized, it is wider than the length L20 (fig. 1) of the sizing roll 20. To collect the sizing agent falling in the cur- tain C at the areas over the length L20 of the sizing roll 20 a deckle 15 is arranged at or in immediate vicinity of the end of the sizing roll 20 at each end of the sizing roll 20. Also, at each end of the curtain C the edge guide 18 is arranged, which guides the edge of the curtain C and the sizing agent falling in the curtain C at the areas over the length L20 of the sizing roll 20 to the deckle 15. The edge areas 25 of the sizing roll 20 are provided with advantageously additional doctor 17 (fig. 2A- 2B) and/or washing means for cleaning the end of the sizing roll 20 of the possible sizing agent. The end of the edge guide 18 is located over or in the deckle 15, ad- vantageously below surface level of the sizing agent collected into the deckle 15.

The system may comprise means to guide the sizing agent from the deckle 15 to disposal or for further use, for example an outlet 35 (figs. 4A-4B). The sizing agent falling with the curtain C onto the edge areas 25 of the sizing roll 20 not covered by the fiber web W to be sized is advantageously cleaned by a cleaning system, for example removed by a doctor 17 (figs. 2A-2C). The end corner of the sizing roll splits the sizing agent layer on the end of the edge areas 25 of the surface of the sizing roll 20 and guides the extra, excessive sizing agent to the deckle 15. 20 In figures 4A-4B is shown examples of controlling surface level of sizing agent lev- el in the deckle 15. In figure 4A the surface level of the sizing agent collected in the deckle 15 is controlled by a control arrangement comprising a float 31 floating on the surface of the sizing agent in the deckle 15. The float 31 is connected to a shaft 32, to another end of which an elastomeric plug 33 is connected. Depending on height of the surface level on which the float is floating height position of the o elastomeric plug 33 is adjusted and thus flow via the outlet 35 of the deckle 15 is

O adjusted so that the flow keeps the deckle 15 not overflowing. The sizing agent is — removed from the deckle via an outlet pipe 38. In figure 4B the surface level of the

A sizing agent collected in the deckle 15 is controlled by a control arrangement com- 7 30 prising a siphon 36 connected to the outlet 35 of the deckle 15. By the siphon 36 = the sizing agent is guided to an at desired height located collector 37 with an outlet 3 pipe 38. Depending on height of the surface level of the deckle 15 is controlled by 5 siphon principle so that the siphon flow keeps the deckle 15 not overflowing.

N The edge areas 25 of the sizing roll 20 may comprise different types of cleaning systems, for example water or other cleaning fluid may be sprayed onto the edge areas 25 by spray jets or like. Also, different types of contacting cleaning system, such as sponges or brushes may be used.

As described above and shown in the examples of the figures on the method of treating the fiber web the fiber web W is coated by the curtain coating or sized by curtain sizing in the coater / sizer comprising the curtain coating / sizing device 10 with the at least one rotatable coating / sizing roll 20 by out-board curtain coating / sizing method, in which the curtain C of coating color / sizing agent falls as a cur- tain wider than width of the fiber web W to be coated / sized as the curtain C falls downwards. Each end of the curtain C is guided by the edge guides 18 and the curtain C has width LC wider than length L20 of the coating / sizing roll 20 and in the method the coating color / sizing agent layer on the end of the edge areas 25 of the coating color / sizing agent on the surface of the coating / sizing roll 20 is split by a corner-effect of an end corner of the coating / sizing roll 20. Advanta- geously, in the method the coating color / sizing agent falling in the curtain C at the areas over the length L20 of the coating / sizing roll 20, i.e. extra, excessive coat- ing color / sizing agent, is collected at each end of the coating / sizing roll 20 into deckles 15 arranged correspondingly at or in immediate vicinity of each end of the coating / sizing roll 20. Advantageously, in the method longitudinal edge areas 25 of the coating / sizing roll 20 not covered by the fiber web W to be coated / sized are cleaned by a cleaning systems comprising a doctor 17. Advantageously, in the method by centrifugal forces created by the rotating coating / sizing roll 20 splitting of the coating color / sizing agent layer on the end of the edge areas 25 of the coating color / sizing agent on the surface of the coating / sizing roll 20 is en- hanced. The treatment system for treatment of the fiber web comprises the curtain — coater or sizer comprising the at least one coating / sizing roll 20 and the curtain o coating or sizing device 10 comprising a nozzle opening / nozzle openings provid-

O ing a coating / sizing curtain C wider than width of the fiber web W to be coated / — sized. The treatment system further comprises edge guides 18 located at each

A end of the curtain C and in the curtain device 10 the nozzle opening/s are located 7 30 in longitudinal direction of the curtain device 10, i.e. in cross-direction of a fiber = web W to be coated / sized such, that the curtain C has width LC wider than length 2 L 20 of the coating / sizing roll 20 and an end-corner of the coating / sizing roll 20 is 5 provided to split by a corner-effect the coating color / sizing agent layer on the end

D of the edge areas 25 of the coating color / sizing agent on the surface of the coat-

N 35 ing / sizing roll 20. Advantageously, at each end of the coating / sizing roll 20 the deckles 15 are arranged at or in immediate vicinity of each end of the coating / siz- ing roll 20 to collect the coating color / sizing agent falling in the curtain C at the areas over the length L20 of the coating / sizing roll 20, i.e. extra, excessive coat- ing color / sizing agent. Advantageously, the treatment system further comprises cleaning systems located at longitudinal edge areas 25 of the coating / sizing roll 20 not covered by the fiber we W to be coated / sized. Advantageously, the clean- ing system comprises the doctor 17.

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Reference signs used in the drawing: 10 curtain application device 15 deckle 17 doctor 18 edge guide 20, 21 sizing roll 25 edge area of the sizing roll 31 float 32 shaft 33 elastomeric plug 35 outlet 36 siphon 37 collector 38 outlet pipe

C curtain

LC width of the curtain

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LW width of the fiber web

T L20 length of the sizing roll

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I S running direction of the fiber web 3 20 Wrfiber web

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Claims

1. Method of treating a fiber web, in which method the fiber web (W) is coated by curtain coating or sized by curtain sizing in a coater / sizer comprising a curtain coating / sizing device (10) with at least one rotatable coating / siz- ing roll (20) by out-board curtain coating / sizing method, in which the cur- tain (C) of coating color / sizing agent falls as a curtain wider than width of the fiber web (W) to be coated / sized as the curtain (C) falls downwards and each end of the curtain (C) is guided by an edge guide (18), character- ized in that the curtain (C) has width (LC) wider than length (L20) of the coating / sizing roll (20) and that in the method the coating color / sizing agent layer on the end of the edge areas (25) of the coating color / sizing agent on the surface of the coating / sizing roll (20) is split by a corner-effect of an end corner of the coating / sizing roll (20).

2. Method according to claim 1, characterized in that in the method by cen- trifugal forces created by the rotating coating / sizing roll (20) splitting of the coating color / sizing agent layer on the end of the edge areas (25) of the coating color / sizing agent on the surface of the coating / sizing roll (20) is enhanced.

3. Method according to claim 1 or 2, characterized in that in the method the coating color / sizing agent falling in the curtain (C) at the areas over the length (L20) of the coating / sizing roll (20), i.e. extra, excessive coating color / sizing agent, is collected at each end of the coating / sizing roll (20) into deckles (15) arranged correspondingly at or in immediate vicinity of each end of the coating / sizing roll (20). O O 25 4. Method according to any of claims 1 - 3, characterized in that in the meth- — od longitudinal edge areas (25) of the coating / sizing roll (20) not covered A by the fiber web (W) to be coated / sized are cleaned by cleaning systems 7 comprising a doctor (17). Ao

> 5. Treatment system for treatment of a fiber web, which comprises a curtain S 30 coater or sizer comprising at least one coating / sizing roll (20) and a curtain 2 coating or sizing device (10) comprising a nozzle opening / nozzle openings S providing a coating / sizing curtain (C) wider than width of the fiber web (W) to be coated / sized, which treatment system further comprises edge guides (18) located at each end of the curtain (C), characterized in that in the cur-

tain device (10) the nozzle opening/s are located in longitudinal direction of the curtain device (10), i.e. in cross-direction of a fiber web (W) to be coated / sized such, that the curtain (C) has width (LC) wider than length (L20) of the coating / sizing roll (20) and that an end-corner of the coating / sizing roll (20) is provided to split by a corner-effect the coating color / sizing agent layer on the end of the edge areas (25) of the coating color / sizing agent on the surface of the coating / sizing roll (20).

6. Treatment system according to claim 5, characterized in that at each end of the coating / sizing roll (20) deckles (15) are arranged at or in immediate vicinity of each end of the coating / sizing roll (20) to collect the coating col- or / sizing agent falling in the curtain (C) at the areas over the length (L20) of the coating / sizing roll (20), i.e. extra, excessive coating color / sizing agent.

7. Treatment system according to claim 5 or 6, characterized in that the treatment system further comprises cleaning systems located at longitudinal edge areas (25) of the coating / sizing roll (20) not covered by the fiber web (W) to be coated / sized.

8. Treatment system according to claim 7, characterized in that the cleaning system comprises a doctor (17). O QA O N n O I = O O K LO 00 O N