AT511861A2 - Arrangement and method for the production of paper and cardboard - Google Patents

Abstract

Arrangement for the production of paper or cardboard, comprising a spray application unit (10), which spray nozzles (4, 5) for spraying a glue mixture at least on a surface of the web (6) and a press nip (3) for pressing the web after spraying Comprising glue mixture, wherein the press nip is formed by two mutually loadable rotatable pressing elements (1, 2), and the arrangement comprises a first drying plant (20) in front of the spray application system (10) for drying the web before the spray application process. The assembly has in front of the spray application system (10) a moistening system (11; 12) which is configured to profile the web (6) prior to spray application with moisture, and if the inlet moisture of the web prior to spray application is below 15% Humidification system configures the web to dampen 15-50% inlet before spray application. Method for producing paper and cardboard.

Description

FIELD OF THE INVENTION

The invention relates to an arrangement and method for the production of paper and cardboard. Particularly, but not exclusively, the invention relates to control over

Strength properties of paper and board in spray surface sizing.

BACKGROUND OF THE INVENTION

Paper or cardboard, for example fine paper or outer packaging cardboard, such as surface paper (liners) of corrugated cardboard or corrugated paper (fluting), may at certain points in the production process be treated with a liquid glue which increases the strength of the paper web. The treatment of the web with glue substantially influences the strength properties of the end product. As a glue usually different types of starch are used, which many different types of additives can be added. This invention is not limited to a particular glue mixture and glue is understood here to be at least partially absorbent in the web to be treated, the strength of the paper web increasing mixtures.

The manufacturer of the paper has set itself the goal of optimizing the composition of the pulp, the amount of mass and the surface sizing, in order to achieve the required strength properties of the final product and the required running properties of the machine. This is a process that is difficult to control, and certain strength values to be achieved with the aid of surface sizing depend on, among other things, the amount of glue, the type of application, the surface-glue solid, and the nip load.

Increasing the moisture of the sizing-in paper web at the size press is limited by the moisture of the outgoing paper web, which moisture substantially affects the break-off sensitivity of the web. The increase in moisture of the paper web entering for sizing is typically limited by the moisture profile which greatly increases the increase in moisture content

Moisture content of the web is weakened. For this reason, the paper web is typically dried to a moisture content of about 4-10% before being sized with the sump press or the film transfer press.

One known way of reducing the tear sensitivity of the web prior to surface sizing is to over-dry the web. The web may be overdried in the dryer section located in front of the surface sizing machine to reduce the moisture profile peaks. If necessary, the overdried paper web must be moistened before rolling up. It is known that problems with driveability can be avoided by overdrying the web rather than leaving the web wet or overly wet. If the moisture profile is poor, the web will stretch unevenly, making driveability more difficult and increasing the amount of web breakage. If the moisture profile varies during film sizing, the web will pick up a different amount of glue and, as a result, the web will not become homogeneous. 3 • · * »* ·» i • ·

One known way of preserving the moisture profile of the web during surface sizing is to profile the web in conjunction with the spray application. In this case, more surface glue is metered into the additional moisture-requiring points, with which the desired amount of moisture is transferred to the web for moisture profiling. But the distortion of the profile of the glue can become a problem. Typically, the edges of the web require moisture profiling because they dry more than the middle portion of the web. In some cases, the spray application system at the web causes profiling errors. In summary, it can be stated that, in connection with the surface sizing, there is a need for profiling both in the area of the web entering the spray application and in the area proceeding there.

The publication WO03004770A1 shows a process for producing a paper or paperboard to be treated with glue. In the publication W02006058961A1 a method for spraying the glue on cardboard or paper is presented.

SUMMARY

According to a first aspect of the invention, there is provided an assembly for making paper or board, the system comprising a spray application unit comprising spray nozzles for spraying the glue mixture to at least one surface of the web and a press nip for pressing the web after spraying the glue mixture, wherein the press nip is formed by two mutually loadable rotatable pressing elements, and the system comprises a first drying plant in front of the spray application system for drying the web before the spray application process. The assembly comprises a humidifier in front of the spray application unit configured to moisture profile the web prior to spray application, and if the inlet moisture of the web is below 15% prior to spray application, the humidification system is configured to set the web to 15-15 inlet humidity. 50% before the spray application process.

Preferably, the system is configured to wet the web to an inlet moisture of 15-30%.

Preferably, the spray application system is configured to spray the glue to be sprayed on the web in a higher

Solids genalt as normal to dose, preferably 15-30%.

The web may also be first dried so that the moisture profile of the web becomes substantially more uniform and then the web can be moistened with the moistening system prior to spray application.

The spray application system is preferably configured to meter the amount of glue to be sprayed onto the web separately from the inlet moistening.

Preferably, the humidification system is configured to wet the web in conjunction with the inlet humidification. The assembly is preferably configured to profile the web at the first dryer with moisture, the dryer being provided as a profiling dryer. 5 5

»* # * *« «« * * * *

A profiling humidification system may comprise at least one of the following devices:

Moistening device, spray application system. A profiling drying plant can have at least one of the following devices: infrared dryer, suspended dryer, steam box.

Preferably, the humidification system is arranged in the first drying plant. The humidification system can be arranged in the vicinity of the drying cylinder of the drying plant (for example below the drying cylinder) or in the region of the web between two drying cylinders.

The arrangement preferably comprises a measuring device for the first web, which measuring device is arranged after the moistening system. The first measuring device is preferably arranged in the web area between the first drying installation and the spray application installation. The first measuring device can also be arranged after the moistening system of the first drying plant.

Preferably, the arrangement comprises a second drying plant after the spray application plant for drying the web before rolling. Preferably, the arrangement comprises a reel which is arranged after the second drying plant for rolling up the web.

Preferably, instead of the first measuring device for the web or in addition to the first measuring device for the web, the arrangement comprises a second measuring device, which is arranged downstream of the spray application system. Preferably, the second measuring device is in the web area 6

arranged between the second drying plant and the reel-up.

The first and / or the second measuring device is provided to measure the moisture profile of the web. The first and the second measuring device preferably comprises a measuring frame.

Preferably, the first and / or the second measuring device at the profiling inlet humidification is switched back, and the humidifier is adjustable due to the measurement.

The moistening beam may extend in the transverse direction of the web only to a part of the web. The web can be moistened in the area of the moistening bar. On one edge or both edges of the web can be

Humidification bar be arranged. The distribution / amount of humidifying nozzles in the humidifying bar may vary on the web width (especially in the marginal areas).

According to another aspect of the invention, there is provided a method of making paper and board wherein the glue mixture is sprayed onto at least one surface of the web in a spray application plant comprising spray nozzles. The web is pressed after spraying the glue mixture in the press nip, which is formed of two mutually loadable, rotatable pressing elements, and the web is dried before the spray application process. In the process, the web is profiled with moisture prior to the spray application, and if the inlet moisture of the web is below 15% before the spray application, the

The web is moistened to an inlet moisture of 15-50% before the spray application.

Preferably, the web is moistened to an inlet moisture of 15-30%.

Preferably, the glue to be sprayed onto the web is metered at a higher solids content than normal, preferably 15-30%.

The web may also be first dried prior to moistening prior to spray application so that the moisture profile of the web becomes substantially more uniform, and then the web is moistened prior to spray application.

Preferably, the amount of glue to be sprayed onto the web is metered separately from the inlet moistening.

Preferably, the web is profiled in conjunction with the inlet moistening with moisture. Preferably, the web with dryer, which is profiled, with

Moisture profiled.

The inlet moistening is preferably provided with the aid of the moistening system, which is profiling, and may have at least one of the following devices: moistening device, spray-aping device. A profiling drying plant may comprise at least one of the following devices: infrared dryers, suspended dryers, steam boxes.

Preferably, the humidification system is arranged in the first drying plant. The humidification system can be connected to the 8 «· · * *» * · * *

Position of the drying cylinder of the drying plant to be arranged (for example, below the drying cylinder) or in the region of the web between two drying cylinders.

Preferably, the web is measured after the inlet moistening before the spray application. Preferably, the web is measured with a first measuring device for the web, which is arranged after the moistening device. The web can also be measured (with the aid of the first measuring device) in conjunction with the drying after the inlet moistening.

Preferably, the web is dried prior to rolling with a second drying unit after the spray application. Preferably, the web is rolled up by means of the reel-up, which is arranged after the second drying plant.

The web may be measured instead of the first measuring device for the web or in addition to the first measuring device for the web by means of a second measuring device after the spray application process. Preferably, the web is measured between drying after the spray application process and rolling up.

In the first and / or the second measurement, the moisture profile of the web is measured.

Preferably, the measurement of the web is switched back to the profiling inlet moistening and the inlet moistening is regulated on the basis of the measurement of the web. 9 • »

With the help of arranged in front of the spray application system humidification, which controls the inlet moisture of the incoming spray to the spray system is higher than the normal inlet moisture is increased, in connection with the surface sizing caused by the spray application error in the incoming to the spray application system web and the the spray application system expiring web be repaired. In addition, the strength of the web can be improved. The strength of the web may be further increased by using a higher solids content of the size than usual. The amount of drying can be kept constant if, instead of the known overdrying, part of the drying can be carried out after spray application. Here, the profiling of the glue as one of the

Moisture profiling take separate action without mixing the profiling of the glue in the spray system.

With the help of a high solids content of the glue, the increase in moisture arising during gluing can be reduced. With the same amount of glue, a greater increase in strength can be achieved, which in turn reduces the need for drying and increases resource savings. The speed of the machine can be increased by adding a spray application for surface sizing and a profiling moistening system prior to spray application.

In connection with the surface sizing, a parametric model can be created with the help of which at least one of the following listed factors can be set automatically: Inlet moisture of the 10

Web, moisture profile, amount of glue, solids content of the glue, temperature of the glue, nip load. Thus, the desired strength properties can be achieved without endangering the drivability of the fiber web machine. The automatic placement hit allows strength values to be quickly optimized and human errors eliminated from the regulation of the surface sizing system.

The properties of the sizing running web or its mass can be measured and with their help the required sizing type or combination can be automatically created.

According to one example, one side of the web is treated with low solids surface sizing to achieve a sufficient amount of glue and the system automatically selects and regulates the amount of glue needed on the different sides of the web, the solids and the nip load.

In the regulation system, a downshift can be built by measuring the strength samples from the web. The arrangement may also be informative by giving the operator instructions on how to achieve the strength values.

The adhesive grades may include cartons, topsheet of corrugated board, corrugated paper, fine paper, and newspaper. The liquid mixture to be applied may be starch, PVA, silicone, coating color, latex, pigment-surface-gluing or a similar treatment agent typically applied to the fibrous web. XI «· ι · ·

Various embodiments of the present invention are or are described only in connection with one aspect or some aspects of the invention. One skilled in the art will understand that any embodiment of an aspect of the invention may be practiced alone or in combination with other embodiments in the same and other aspects of the invention.

BRIEF DESCRIPTION OF THE FIGURES

The invention will now be described by way of example with reference to the accompanying drawings. The figures show:

FIG. 1 shows a spray application system in which the press nip is formed by two pressing elements;

FIG. 2 shows a fiber web machine to which the arrangement of the invention has been applied and in which possible positions are shown for the wetting of the web to be carried out before the spray application and for the measurement of the web;

Figure 3 shows schematically the SCT strength of a surface sized board with various amounts of glue and moisture;

Figure 4 shows schematically the RCT strength of a surface sized board with various amounts of glue and moisture;

Figure 5 shows schematically the CMT30 strength of a surface-sized carton with various amounts of glue and moisture; and

Figure 6 shows schematically the Huygen strength of a surface glued carton with various amounts of glue and moisture. 12 > · · · 4 · · · * I 4 «· - ** f * * * · 4 4 4 4 · ** · < *

DETAILED DESCRIPTION

It should be noted that the figure to be represented does not fully correspond to the scale, and that it serves at first only to illustrate the various embodiments of the invention.

In Fig. 1, a spray application system 10 is shown, which has two against each other to be loaded pressing elements, a first roller 1 and a second roller 2. The pressing elements 1, 2 form a press nip 3 between them. The paper or board web 6 is then fed into the press nip when preferably a high solids glue mixture is sprayed onto the web. The spray application system 10 has first spray nozzles 4 and / or second spray nozzles 5 in front of the press nip. The web can be treated with a glue mixture on one or both sides with the aid of the first spray nozzles 4 and / or the second spray nozzles 5 with glue.

The glue is applied to the web, preferably with a spray application spray applicator before the press nip.

As pressing element and one or more bands can be used. Preferably, the belt is passed over a roller nip. The press roll may also be formed as a bend-compensated roll to allow high line loading in the press nip. With the aid of a deflection-compensated roll, a high and uniform contact pressure can be produced in the press nip and the penetration of the glue mixture into the web can be improved. Due to the use of 13: a deflection-compensated roll, it is also possible to reduce roll diameters significantly in comparison with the tube rolls.

In Fig. 2, an arrangement is shown, which has a first drying group 20, a spray application system 10, a second drying group 21 and a reel 30.

The spray application system 10 has spray nozzles for spraying the glue mixture on at least one surface of the web and a press nip for pressing the web after spraying the glue mixture, wherein the press nip is formed by two rotatable pressing elements 1, 2 which are loadable against each other.

The assembly has a first dryer section 20 (the first dryer) in front of the spray application system 10 for drying the web prior to the application process. The assembly has a humidification system in front of the spray application unit which is configured to profile the inlet moisture of the web prior to spray application by increasing the inlet moisture of the web and the spray application unit is configured to profile the amount of glue in the web separately from the dampening profile.

The humidification system 11; 12 is arranged in the first drying group. A first possible position of the humidifier is at the drying cylinder 22 in the dryer section (e.g., below the drying cylinder). A second possible position of the humidification system 12 is in the web area between two drying cylinders. 1¾

The system comprises a measuring device 13 for the first web, which after the moistening device 11; 12 is arranged. Preferably, the first measuring device 13 is arranged in the web region between the first drying group 20 and the spray application system 10. The first measuring device can also be arranged in the first drying plant after the humidification system.

The assembly includes a second dryer section 21 (the second dryer) after the spray applicator 10 for drying the web prior to rolling up. The arrangement comprises a reel-up 30 which is arranged after the second drying group for reeling the web.

The arrangement comprises instead of the first measuring device 13 of the web or in addition to the first measuring device 13 of the web, a second measuring device 14, which is arranged after the spray application system 10. Preferably, the second measuring device 14 is arranged in the web area between the second drying group 21 and the reel-up 30.

With the aid of FIGS. 3-6, relevant differences in increasing the strength of a web 6 moistened to a higher inflow than usual and then treated with glue can be illustrated. Significant differences arise between different glue treatments when sprayed on the web glue mixtures, which have a different solids content and a different inlet moisture and then the web was pressed in the press nip. In particular, it was noted that when the webs were wetted to a humidity of 15%, increased strength values could be measured as compared to the comparative webs whose run-in moisture was not increased. The representations, which are wet on dampness of 15%, consist of measuring points and lines connecting the measuring points.

In the schematic diagrams of FIGS. 3-6, the measured quantity of starch with a unit g / m2 is represented by means of the horizontal axis. With the aid of the vertical axes, the increase of different types of strength in percent is shown on the left. The vertical axes on the right show solid contents of one and the same glue in different measurement sets (the first percentage, in two cases the other percentage describes a higher inlet moisture of 15%).

The SCT cd strength of a surface sized 142 g / m2 green cardboard in the transverse direction of the web is shown in Fig. 3, in which the percentage increase in SCT cd strength is measured by means of the vertical axis and by the horizontal axis as measured in the web Amount of starch can be represented as grams per square meter.

The RCT cd strength of a surface sized 142 g / m.sup.2 green cardboard in the transverse direction of the web is shown in FIG. 4, in which the percentage increase in RCT cd strength is determined by the vertical axis and that in the web by the horizontal axis measured amount of starch can be represented as grams per square meter.

The CMT30 strength of a surface sized 142 g / m2 green cardboard in the transverse direction of the web is shown in Fig. 5, in which the percentage increase in CMT30 strength is determined by the vertical axis and the amount of starch measured in the web by the horizontal axis Grams per square meter.

The Huygen strength of a surface sized 142 g / m2 green cardboard in the transverse direction of the web is shown in Fig. 6, in which the percentage increase in Huygen strength is determined by the vertical axis and the amount of starch measured in the web by the horizontal axis Grams per square meter.

It can be seen from the schemes shown in Figures 3-6 that for a size-treated web, the same improvement in strength can be achieved with lower levels of glue if the web is wetted prior to spray application. If the solid content is increased (in examples, the solid content of the glue mixture is 15% and 20%), the strength can be significantly improved inexpensively, and if necessary, the production capacity can be increased.

The present description provides non-limiting examples of some embodiments of the invention. However, it will be apparent to those skilled in the art that the invention is not limited to the details shown, but that the invention may be embodied in other equivalent ways. Some features of the illustrated embodiments may be utilized without the use of the other features.

As such, the present description should be considered as a description of the principles of the invention rather than as a description limiting the invention.

Thus, the scope of the invention is limited only by the appended claims.

Claims (19)

1. Arrangement for the production of paper or cardboard, wherein the arrangement comprises a spray application system (10), which spray nozzles (4, 5) for spraying a glue mixture at least on a surface of the web (6) and a press nip (3) for pressing the web after spraying the glue mixture, wherein the press nip is formed by two mutually loadable rotatable pressing elements (1, 2) and the arrangement comprises a first drying plant (20) in front of the spray application system (10) for drying the web before the spray application, characterized in that the arrangement in front of the spray application system (10) has a moistening system (11, 12) which is configured to profile the web (6) with moisture prior to the spray application, and if the inlet moisture of the web in front of the spray application system is below 15%, if the humidification system configures the web to an inlet humidity of 15 - 50% before the spray application to moisten. 2. Arrangement according to claim 1, characterized in that the arrangement is configured to moisten the web (6) to an inlet moisture of 15 - 30%. 3. Arrangement according to claim 1 or 2, characterized in that the spray application system (10) is configured to dose to the web to be sprayed glue in a high solids content of 15 - 30%. 4. Arrangement according to one of the claims 1-3, characterized in that the spray application system (10) is configured to dose to the web to be sprayed amount of glue separated from the inlet moistening. 5. Arrangement according to one of the patent claims 1-4, characterized in that the humidification system (11; 12) in the first drying plant (20) is arranged. An arrangement according to any one of claims 1-5, characterized in that the arrangement comprises a first measuring device (13) for the web, which is arranged after the moistening system (11; 12), and the arrangement instead of the first measuring device for the web or in addition to the first measuring device for the web has a second measuring device (14), which is arranged after the spray application system (10). 7. Arrangement according to claim 6, characterized in that the first (13) and / or the second measuring device (14) to measure the moisture profile of the web (6) is provided. 8. Arrangement according to claim 6 or 7, characterized in that the first (13) and / or the second measuring device (14) is fed back with the profiling inlet humidification, and the humidifying system (11; 12) is adjustable due to the measurement. 9. Arrangement according to one of the claims 1-8, characterized in that the arrangement comprises a second measuring device (21) after the spray application system (10) for drying the web before rolling. so:: A method of producing paper or board, which method comprises spraying a glue mixture onto at least one surface of the web (6) in a spray application unit (10) having spray nozzles (4, 5) and the web after spraying the glue mixture in the press nip (3) is pressed, which is formed by two mutually loadable and rotatable pressing elements (1, 2), and the web is dried before the spray application (20), characterized in that in the process the web (6) before the spray application is profiled with moisture and when the inlet moisture of the web before the spray application system (10) is below 15%, the web (6) to the inlet moisture 15 - 50% is moistened (11, 12). 11. The method according to claim 10, characterized in that the web (6) is moistened to an inlet moisture of 15 - 30%. 12. The method according to claim 10 or 11, characterized in that on the web to be sprayed glue in a solids content of 15 - 30%, which is higher than usual, is metered. 13. The method according to any one of the claims 10-12, characterized in that the web (6) before the before the spray application (10) provided moistening (11, 12) is dried so that the moisture profile of the web is much more uniform and the web is then moistened before the spray application. 14. The method according to any one of the claims 10-13, characterized in that the amount of glue to be sprayed onto the web is metered separately from the inlet moistening. 15. The method according to any one of the claims 10-14, characterized in that the web is profiled in conjunction with the inlet moistening (11, 12) with moisture. 16. The method according to any one of the claims 10-15, characterized in that the web by means of a drying plant (20), which is profiling, is profiled with moisture. 17. The method according to any one of the claims 10-16, characterized in that the web after the inlet moistening before (13) of the spray application (10) and / or after (14) of the spray application is measured. 18. The method according to claim 17, characterized in that the moisture profile of the web is measured. 19. The method according to claim 17 or 18, characterized in that the measurement to be carried out on the web is fed back with the profiling inlet moistening and the inlet moistening is regulated on the basis of the measurement of the web. Vienna, July 12, 2012 Metso Paper, Inc. by: eschmann Haffner and, Patentanwtt