EP2066841B1 - Method for producing a coated paper, paperboard or other fibrous web - Google Patents

Abstract

The invention relates to a method for producing a coated paper, paperboard or other fibrous web, having the following steps: web formation from a fibrous material mixture, having a headbox (2) and a wire section (3), dewatering in a pressing section (4), drying in a drying section (6) which comprises drying cylinders (5), in order to dry the fibrous web (7) which is formed at least as far as a residual moisture content, application of a simultaneous precoating to both web sides (7a; 7b) by way of a size or film press (8) for applying starch or pigment-containing application medium, afterdrying with contactless dryers (9) and an afterdrying section (11) which comprises drying cylinders (10), and presmoothing (12) by way of a soft nip or hard nip calender (12a), reeling (25). According to the invention, a pigment-containing application medium (13) is applied to only one web side (7a) of the fibrous web (7) in an online process after the presmoothing (12), for which purpose a first coating device, for example a film coater (14), is used for applying the application medium (13) indirectly by means of an applicator roll (14a) and/or a second coating device, for example a blade coater (15), is used for applying the application medium (13) directly, and wherein both abovementioned coating devices or coaters (14; 15) can be operated as desired and the fibrous web (7) in the process maintains a predefined web running path which extends as far as over subsequent stationary, contactless drying (17).

Description

The invention relates to a process for the production of a coated paper, board or other fibrous web with the following steps: formation of a fiber mixture, with a Stoffauffauf and a wire section, dewatering in a press section, drying in a dryer section consisting of drying cylinders to the formed To dry fibrous web at least to a residual moisture content, applying a simultaneous primer on both sides of the web with a glue or film press, for applying starch or pigment-containing application medium, post-drying with non-contact dryers and an existing drying cylinders night after dryer section, as well as pre-smoothing with a Softnipp- or Hartnipp - calender.

Such methods are already known in practice. To achieve a high quality, the fibrous web is usually still provided with at least one top coat. For this purpose, several coating devices are often used. For example, external film coater and blade coater and a final external smoothing, so in the offline process used.

The coating with different coating units or coater types is currently only possible offline and with the formation of different, complicated and long Bahhlaufwegen. In addition, a separate drying or with shifted driers is necessary after each application process Moreover, the transfer of the fibrous web is complicated in these areas.

From the WO00 / 70144 A1 For example, a method is known for producing fine paper, in which pre-candering, two-sided precoating, drying and then one or more coatings are provided.

The latter coatings are carried out with doctor elements, jet or spray applications. Only then does a non-contact drying take place. A change in the type of paper to be produced by a special design of the headbox and the components for the pulp.

The object of the invention is therefore to provide an on-line method which does not have the disadvantages mentioned.

The object of the invention is achieved with a method according to the characterizing part of Claim 1 solved.

According to the invention, after the pre-smoothing in an on-line process, a pigment-containing application medium is applied to only one web side of the fibrous web, for which a first coating device, for example a film coater for application of the application medium in an indirect manner by means of an applicator roll and / or a second Coating device, such as a Bladecoater for applying the application medium is used in a direct manner and wherein both mentioned coating devices or coaters are selectively operable and thereby retains the fibrous web a predetermined, over a subsequent stationary contactless drying ranging web travel path.

At the same time, the invention "kills several birds with one stone". On the one hand, the fibrous web is not burdened too much by the single-sided application and therefore tends to tear off far less. On the other hand, due to the short web path maintained between the two types of coater (film coater and blade coater), good runability and thus a considerably less expensive production process are possible. In addition, it saves at least one additional contactless drying unit, which in a previously performed bypass web guide for an alternate coating option, for example, to get from one coater to another coater, would be necessary.

Very advantageous now is the ability to perform the entire manufacturing process online, which saves you an additional reeling and unwinding.

A particularly advantageous embodiment of the invention is that it is possible to use either only one of said coating devices, or coater, which the desired Apply application medium on one side of the web or use both types of coater, for example film and then a blade coater in succession. In the latter possibility is of particular advantage that you can do without Providence of an intermediate drying, whereby further costs and effort can be saved. This variable possibility of the type of coating increases the flexibility of the method. For example, different types of paper can be treated with a single coating concept.

It should be mentioned in this context that the order of the coating devices is variable. However, the arrangement of a film and then a blade coater is preferred first, because a more uniform coating layer is thereby expected.

In an embodiment of the invention, it is provided that, following further drying, a pigment-containing coating medium is applied in the same way as described above, also on the second side of the sheet. This achieves a high-quality double-sided coated fibrous web, in particular a paper coated on both sides, which can then be printed particularly well, for example.

Another very expedient solution of the invention is that the coated fibrous web is finally smoothed, such that either each side of the web is treated individually and sequentially with at least one one-nip calender or both sides with at least one multi-tip calender or a combined , made from single-nipp and multi-tip calendars.

By providing the said combination of calenders, it is possible to produce both matte and glossy paper in the same machine or concept.

It should also be added that the said film coater is equipped with an applicator roll assigned to the web side to be coated. This application roller is in turn associated with an application unit, for example a nozzle unit, which delivers the application medium to the application roller and from which the application medium is transferred to the web side of the fibrous web to be coated. This coating process is referred to as indirect application.

On the other hand, the said blade coater downstream of the fibrous web runs, with one of the web applicator units to be coated and a downstream doctoring element or nozzle applicator with short exposure time (SDTA, i.e. Short Dwell Time Applicator), the application medium in the process according to the invention on the same side of the web. As a nozzle application unit, for example, a so-called free-jet nozzle unit can be used, which is sold by the company of the applicant under the name "Jetflow". This type of order is referred to as a direct order, because just the application medium directly, ie without transfer element, such as the applicator roll, is applied to the fibrous web.

An alternative embodiment of the invention may consist in that instead of arranging both types of coater successively on the web travel path of the fibrous web and to use mutually by pivoting the desired coater, it is also possible to use only one module of a Coaterart. For selectively operating one of said coating devices or coaters, a provided module of a coater type, for example the film coater, is exchanged in a simple manner for the other existing module of the other coater type, for example the blade coater or vice versa.

It should be added that the mentioned predrying can be an impingement drying developed and sold by the company of the applicant.

It should also be added that in certain cases it makes sense to pre-smooth the fibrous web before the first line, that is to say before the first application of the application medium, in particular with a film coater. The order quality can be increased thereby.

The inventive method is particularly suitable for the production of LWC (Light Weight Coated) or MWC (Middle Weight Coated) - papers that can be both wood-free and wood-containing.

The method allows high machine speeds of more than 1300 m / min, in particular more than 1500 m / min.

Based on embodiments, the invention will be explained in more detail.

Figur 1:

in schematischer Darstellung eine Gesamtmaschine zur Herstellung einer beschichteten Faserstoffbahn in der das erfindungsgemäße Verfahren stattfindet.

Figuren 2 bis 11:

verschiedene Varianten von Beschichtungsmöglichkeiten, im Anschluss an das Vorkalandern

Show it:

FIG. 1:

a schematic representation of an overall machine for producing a coated fibrous web in which the inventive method takes place.

FIGS. 2 to 11:

different variants of coating options, following the pre-calendering

In the individual figures, the same components are provided with the same reference numerals.

In the FIG. 1 within the fibrous web manufacturing machine 1, the known method steps or machine configurations are only roughly illustrated as a box and mean:

Web formation from a pulp mixture, with a headbox 2 and a wire section 3, dewatering in a press section 4, drying in a Drying cylinders 5 existing drying section 6 to dry the formed fibrous web 7 at least to a residual moisture content. Thereafter, the application of a simultaneous primer on both sides of the web 7a and 7b with a glue or film press 8 for applying starch or pigment-containing application medium. This is followed by a final drying with non-contact dryers 9 and a dryer section 10 consisting of dryer sections 11, as well as pre-smoothing with a soft-nip or a hard-nip calender 12.

According to the invention, following the pre-smoothing 12, in an on-line process, a pigment-containing application medium 13 (coating color) is applied to only one side of the web 7a of the fibrous web 7.

One recognizes in the FIG. 1 in that both a film coater 14 for applying the application medium 13 in an indirect manner and a blade coater 15 for applying the same or a different application medium 16 (possibly in a different composition) are used directly.

It is important in the process control that the fibrous web 7 maintains a predetermined short web travel path extending beyond a subsequent contactless drying 17, consisting of infrared and air dryers 17a, 17b and 17c.

It should also be mentioned that the film coater consists of an applicator roll 14a, which is set against the web side 7a and has a nozzle application unit 14b and a counter roller 14c on the other web side 7b. In the coating process, the applicator roll 14a is pressed against the counter roll 14c, so that a Auftragnipp arises between two rollers 14a and 14c, in which the fibrous web page 7a receives the application medium 13.

The Bladecoater 15 consists of a coating unit 15a and a subsequent doctor element 15b for dosing and / or comparison of Application layer. Both units 15a and 15b are also employed during the coating process against a counter-roller 15c on the other side of the web 7b.

Following the coating of the web page 7a and the subsequent contactless drying 17a to 17c and a contact drying with drying cylinders 18a of a post-dryer section 18, in the example chosen, a treatment of the other web page 7b, but this is not absolutely necessary. For this purpose, the same machine configuration as for the web page 7a - gegengleich- used.

Finally, a calendering of the fibrous web with a combination consisting of at least one Einzelelnipp- calender and / or at least one multi-tip calender, for example, a known Janus calender. The calendering or smoothing is carried out such that either each web page 7a or 7b is treated individually and sequentially with at least one single-nip calender 19 or both web pages 7a and 7b with at least one multi-tip calender 20 or a combined single-nip and multi-tip calenders. The single-nip calenders 19 are preferably made of a combination of heated metal rollers and soft-coated, elastic rollers. With these so-called soft-nib calenders 19 one produces matte, glossy paper, while with the multi-tip calender 20 high gloss is produced.

Since in the present example a combination consisting of single-Nipp 19 and multi-Nipp 20 calenders is provided, it is possible to produce both matte and glossy paper in the same machine or the same concept, depending on which online calenders are used , That's another advantage of the process.

Subsequently, the finished treated fibrous web is rolled up on a reel 25.

With reference to the following figures will be explained how both coaters 14 and 15 described can be used optionally. This show different variants in the FIGS. 2 to 11 ,

In FIG. 2 is shown on different guide rollers 21 and a spreader roller 22 in the direction L continuous fibrous web 7 with flat web guide shown. In this variant, the film coater 14 or the application unit 14b assigned to the application roller 14a applies the application medium 13 to the web side 7a of the fibrous web 7, while the existing blade coater is not in use and therefore also the application unit 15a, the doctor element (or blade) ) 15b and a scraper cleaning 15d for the counter-roller 15c are pivoted.

This track guide is characterized by short trains and easy transfer options.

In FIG. 3 is basically the same flat web guide, which brings the same advantages shown. In contrast to FIG. 2 is here instead of the film coater 14 of Bladecoater 15 for direct application of the application medium 13 or 16 in use. Therefore, the application roller 14a, the application unit 14b and a cleaning scraper 14d for the counter-roller 14c are swung away.

In FIG. 4 is like at FIG. 2 again the film coater 14 in use. Therefore, the description of the FIG. 2 referred, which should not be repeated here. Changed compared to the FIG. 2 is however the web guide. This runs here between the coaters 14 and 15 at an angle. It is advantageous that this is a common design, which is why one can fall back on "standard" - components. However, the trains are a bit longer here.

The variant according to FIG. 5 is in principle similar to that of FIG. 3 , which is why no repetitive description should take place here. However, that's exactly how figure 4 an inclined web guide designed with the same advantages that in FIG. 4 are called.

In FIG. 6 in each case an upwardly rising web guide is provided. In the direction of L, the Bladecoater 15 and then only the Filmcoater 14 is arranged in both figures first. The film coater is installed horizontally here. Both variants allow again advantageous, short trains.

In the variant like. FIG. 6 becomes like at FIG. 2 the application medium 13 is applied to the web side 7a of the fibrous web 7 with the film coater 14, or with the applicator roll 14a and the applicator 14a associated with the applicator roll 14a, while the first arranged Bladecoater 15 is not in use and therefore also the application unit 15a, the doctor element (Blade) 15b and a cleaning scraper 15d for the counter-roller 15c are pivoted.

In the variant according to FIG. 7 is opposite the FIG. 6 instead of the film coater 14, only the blade coater 15 for direct application of the application medium 13 in use. Therefore, the application roller 14a, the application unit 14b and a cleaning scraper 14d for the counter-roller 14c are swung away. This variant is useful if the application medium 13 requires a relatively long exposure time to the contactless drying 17 or this long exposure time is desired.

The variants according to FIGS. 8 and 9 show each compact solutions with advantageous, extremely short train trains. In both variants is again the tilted Filmcoater 14, as in FIG. 4 or 5 and a Bladecoater 15 available. Out FIG. 8 shows that with the film coater 14, or with the applicator roll 14a and the application roller 14a associated application unit 14b the application medium 13 is applied to the web page 7a of the fibrous web 7, while the subsequently arranged Bladecoater 15 is not in use and therefore together with its squeegee element (or blade) 15b is pivoted.

In contrast to the variant according to the FIG. 8 is at the in FIG. 9 shown variant again only the Bladecoater 15 for direct application of the application medium 13 or 16 in use. In both variants according to FIGS. 8 and 9 is used as Bladecoater 15 a so-called Short Dwell Time Applicator (SDTA) 15.1. This SDTA 15.1 works with an application nozzle and an immediately downstream doctoring element for the immediate equalization or adjustment of the coating weight of the applied application medium.

As in FIG. 9 to recognize, this embodiment is particularly compact, since at the same time the counter roll 14c of the film coater 14 otherwise not used here serves as a counter roll for the SDTA 15.1.

Finally, FIGS. 19 and 11 show modular solutions. With these solutions also very short web trains and a very compact design are possible. If only one application layer is to be applied, according to these variants, only one counter-roller 14c with cleaning scraper 14d needs to be installed so that it is resistant to the cold. As exchangeable modules for the optional use of a film coater 14 or a blade coater 15, either elements for film coating serving as M1 in FIG FIG. 10 or blading elements that are in FIG. 11 marked as M2.

Depending on the type of order (film or bladestreich) is desired, these modules can be exchanged against each other. In the figures, the individual modules M1 and M2 are illustrated by dash-dotted lines.

LIST OF REFERENCE NUMBERS

1

making machine

2

headbox

3

Wire section

4

press section

5

drying cylinders

6

drying section

7

Fibrous web

7a

web side

7b

web side

8th

size press

9

Contactless dryers

10

drying cylinders

11

Afterdryers

12

pre-smoothing

12a

Softnippkalander

13

pigmented application medium

14

Filmcoater

14a

applicator roll

14b

Nozzle application unit

14c

backing roll

14d

cleaning scraper

15

Bladecoater

15a

application unit

15b

Rakelement

15c

backing roll

15d

cleaning scraper

16

pigmented application medium

17

contactless drying

17a

infrared dryer

17b

air dryer

17c

air dryer

18

Afterdryers

18a

drying cylinders

19

Single-nip calender

20

Multinipp calender

21

guide roll

22

Spreader roll

25

Reeling

Claims (7)

1. Method for producing a coated paper, board or other fibrous web, having the following steps:

   forming a web from a fibrous mixture by using a flow box (2) and a wire section (3), dewatering in a press section (4), drying in a drying section (6) composed of drying cylinders (5) in order to dry the fibrous web (7) formed at least down to a residual moisture content, applying a simultaneous pre-coat to both web sides (7a; 7b) by using a size or film press (8) for applying starch or

   pigment-containing application medium, after-drying using non-contact dryers (9) and an after-dryer section (11) composed of drying cylinders (10), and pre-calendering (12) with a soft-nip or hard-nip calender (12a), applying an application medium (13) in an on-line process, reeling up (25),

   characterized in that

   following the pre-calendering (12), pigment-containing application medium (13) is applied to only one side (7a) of the fibrous web (7), for which purpose use is made of a first coating device, for example a film coater (14) for applying the application medium (13) in an indirect way by means of an applicator roll (14a) and/or a second coating device, for example a blade coater (15) for applying the application medium (13) in a direct way, and wherein both the said coating devices or coaters (14; 15) can be operated as desired and, in the process, the fibrous web (7) maintains a predetermined web running path, which reaches as far as over a following stationary non-contact drying system (17), wherein optionally in each case only one of the said coating devices or coaters (14; 15) applies the application medium (13) or both the said coaters (14; 15) apply the application medium (13) successively to the same web side (7a) and without the provision of intermediate drying.
2. Method according to Claim 1,
   characterized in that
   following further after-drying (18), a pigment-containing application medium (13) is also applied to the second web side (7b) in the same way.
3. Method according to either of Claims 1 and 2,
   characterized in that
   the coated fibrous web (7) is finally calendered in such a way that either each web side (7a; 7b) is treated individually and successively by using a single-nip calender (19) or both web sides (7a; 7b) by using a multi-nip calender (20), or else combined calendering comprising single-nip and multi-nip calenders (19; 20) is carried out.
4. Method according to either of Claims 1 and 2,
   characterized in that
   the film coater (14) applies the application medium (13) by using an applicator roll (14a) assigned to the web side (7a; 7b) to be coated.
5. Method according to either of Claims 1 and 2,
   characterized in that
   the blade coater (15) applies the application medium (13) by using a nozzle applicator assembly (15a) assigned to the web side (7a; 7b) to be coated and a doctor element or blade (15b) arranged downstream, or a nozzle applicator assembly having a short duration of action (15.1).
6. Method according to one of Claims 1 to 5,
   characterized in that
   in order to operate one of the said coating devices or coaters (14; 15) as desired, a respectively used coater or parts thereof are pivoted against the associated web side (7a; 7b) to be coated or, as a prepared module (M1; M2), is exchanged for the other module (M2; M1) of the coater (14; 15) that is present.
7. Method according to one of Claims 1 to 6,
   characterized in that
   before the coating with the first coating device (14), the fibrous web is pre-calendered.

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