EP2066841A1

EP2066841A1 - Method for producing a coated paper, paperboard or other fibrous web

Info

Publication number: EP2066841A1
Application number: EP07820018A
Authority: EP
Inventors: Stefan Reich; Ingolf Cedra; Oliver Rudolph; Bernhard Kohl; Michael Trefz
Original assignee: Voith Patent GmbH
Current assignee: Voith Patent GmbH
Priority date: 2006-09-20
Filing date: 2007-09-04
Publication date: 2009-06-10
Anticipated expiration: 2027-09-04
Also published as: ATE550488T1; EP2066841B1; JP2010504442A; WO2008034713A1; DE102006044822A1

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

Process for the preparation of a coated paper, cardboard or other

Fibrous web

The invention relates to a process for the production of a coated paper, board or other fibrous web with the following steps: web formation from a pulp mixture, with a headbox 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 web paths. In addition, a separate drying or with displaced driers is necessary after each application process. In addition, the transfer of the fibrous web in these areas is complicated.

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 one the

Possibility to use either only one of the mentioned coating devices, or coater, which has 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. - A -

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, it is also possible, for example, to use a so-called free-jet nozzle aggregate which is distributed by the applicant's company under the name "Jetflow." This type of order is referred to as a direct order, because the application medium is used 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 woodfree and woody.

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.

Show it:

Figure 1: a schematic representation of an overall machine for producing a coated fibrous web in which the inventive method takes place.

Figures 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 FIG. 1, within the fibrous web production 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.

It can be seen in FIG. 1 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 also 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 successively with at least one single-nip calender 19 or both web pages 7a and 7b with at least one multi-tip calender 20 or one 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 is shown by different variants in FIGS. 2 to 11.

FIG. 2 shows the fibrous web 7 with a flat web guide running via different guide rollers 21 and a spreader roller 22 in the direction L. 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 principle, the same flat web guide, which brings the same advantages, is shown in FIG. In contrast to FIG. 2, instead of the film coater 14, the blade coater 15 is used here for the direct application of the application medium 13 or even 16. Therefore, the application roller 14a, the application unit 14b and a cleaning scraper 14d for the counter-roller 14c are swung away.

In Figure 4, as in Figure 2 again the film coater 14 in use. Therefore, reference is made to the description of Figure 2, which should not be repeated here. Changed compared to Figure 2, however, is 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, exactly as in figure 4 an inclined web guide designed with the same advantages that are mentioned in Figure 4.

In Figure 6, an upwardly rising web guide is provided in each case. 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 gem. As in FIG. 2, the application medium 13 is applied to the web side 7a of the fibrous web 7, as in FIG. 2, with the film coater 14 or with the applicator roll 14a and the application unit 14a assigned to the applicator roll 14a, whereas the first arranged blade coater 15 is not in use and therefore also the application unit 15a, the squeegee element (or blade) 15b and a cleaning scraper 15d for the counter-roller 15c are pivoted away.

In the variant according to FIG. 7, in contrast to FIG. 6, instead of the film coater 14, only the blade coater 15 is used for the direct application of the application medium 13. 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 each show compact solutions with advantageous, extremely short track trains. In both variants, the inclined film coater 14 is again present, as in FIG. 4 or 5, and a blade coater 15 is present. From Figure 8 shows that with the film coater 14, or with the applicator roll 14a and the applicator roll 14a associated applicator unit 14b the application medium 13 is applied to the web side 7a of the fibrous web 7, while the subsequently arranged Bladecoater 15 is not in use and Therefore, together with its doctor element (or blade) 15b is pivoted. In contrast to the variant according to FIG. 8, in the variant shown in FIG. 9 again only the blade coater 15 is used for the direct application of the application medium 13 or also 16. In both variants according to FIGS. 8 and 9, a so-called Short Dwell Time Applicator (SDTA) 15.1 is used as blade coater 15. 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 can be seen in FIG. 9, this embodiment is particularly compact, since at the same time the counter-roller 14c of the film coater 14, which is not otherwise used here, serves as counter-roller 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 exchange modules for the optional use of a film coater 14 or a blade coater 15 serve either elements for film coating, which are identified as M1 in Figure 10 or elements for Bladestreichen, which are marked in Figure 11 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 manufacturing machine

2 headbox

3 wire section

4 press section

5 drying cylinders

6 drying section

7 fibrous web

7a train side

7b railway side

8 size press

9 contactless dryers

10 drying cylinders

11 night drying section

12 pre-smoothing

12a soft-nip calender

13 pigment-containing application medium

14 film coater

14a application roller

14b nozzle application unit

14c counter roll

14d cleaning scraper

15 blade coater

15a application unit

15b Rakelement

15c counter roll

15d cleaning scraper

16 pigment-containing application medium

17 contactless drying a Infrared dryerb Air dryerc air dryer

Nachtrockenpartiea drying cylinder

Single-nip calender

Multinipp calender

guide roll

Spreader roll

Reeling

Claims

claims

A process for producing a coated paper, board or other fibrous web, comprising the following steps:

Web formation from a pulp mixture, with a headbox (2) and a wire section (3), dewatering in a press section (4), drying in a dryer section (5) consisting of drying section (6) to the formed

Fibrous web (7) to dry at least to a residual moisture content, applying a simultaneous primer on both sides of the web (7a, 7b) with a size or film press (8) for applying starch or pigment-containing application medium, post-drying with contactless dryers (9) and a from drying cylinders (10) existing after-dryer section (11), as well as pre-smoothing

(12) with a soft-nip or hard-nip calender (12a), reel (25); characterized in that following the pre-smoothing (12) in an on-line process, a pigment-containing application medium (13) on only one web page (7a) of the fibrous web (7) is applied, including a first coating device, such as a film coater (14) for application the application medium (13) is used in an indirect manner 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 manner and wherein both coating devices or coaters (14; 15) are selectively operable and while the fibrous web (7) a predetermined, web travel path, which extends beyond a subsequent fixed contactless drying (17), retains.

2. The method according to claim 1, characterized in that optionally only one of the mentioned coating devices or

Coater (14; 15) applies the application medium (13) or both said coaters (14; 15) successively and without the provision of an intermediate drying the application medium (13) on the same web page (7a) apply.

3. A method according to claim 1 or 2, wherein after a further drying (18), a pigment-containing application medium (13) is also applied in the same way to the second web side (7b).

4. Method according to one of claims 1 to 3, characterized in that the coated fibrous web (7) is finally smoothed, such that either each web side (7a; 7b) is treated individually and successively with a single-nip calender (19) or both sides of the web (7a; 7b) are performed with a multi-tip calender (20) or also a combined smoothing consisting of one-nip and multi-nip calenders (19; 20).

5. Method according to one of claims 1 to 3, characterized in that the film coater (14) applies the application medium (13) to an application roller (14a) assigned to the web side (7a, 7b) to be coated.

6. The method according to any one of claims 1 to 3, characterized in that the Bladecoater (15) with one of the web page to be coated (7a; 7b) associated nozzle application unit (15a) and a downstream doctor blade or blade (15b) or a nozzle application unit with short Einwirkdauer (15.1) the application medium (13) applies.

7. The method according to any one of claims 1 to 6, characterized in that for selectively operating one of said coating devices or coaters (14; 15) of the respectively used coater or parts thereof to the associated, to be coated web page (7a, 7b) pivoted or exchanged as a provided module (M1; M2) with the other existing module (M2; M1) of the coater (14; 15).

8. The method according to any one of claims 1 to 7, d a d u c h e c e n e c i n e, d a s s before coating with the first coating device (14) the

Fiber web is pre-smoothed.