FI115850B - Method and apparatus for supplying a substance to a web - Google Patents

Description

115850 METHOD AND DEVICE FOR MOVING RAIN A AN BACKGROUND ART

The invention relates to a device and method for transferring material to a web, such as a paper or board web. The invention can be used, for example, in paper and board manufacturing processes.

In the process of making paper or board, various substances are added to the web at various stages. In particular, it is common to add various materials to improve the properties of paper and its end-use properties. Processes that add substances include mass sizing, surface sizing, coating, wetting and application of special chemicals.

Mass and surface sizing mainly improve web strength and porosity properties. With current technology, this is usually done by applying an adhesive mixture (e.g. starch-lysate mixture) to the surface of the web in a press nip. In the nip, the adhesive mixture penetrates the web structure by capillary and pressure forces. The press equipment used is, for example, pond glue and film glue press.

In the coating, a coating agent, such as a coating paste, is applied to the surface of the web, which mainly improves the printing and surface properties of the web. The coating material v contains a significant amount of pigment, the surface adhesive does not. Coating methods known in the art include blade coating, rod coating, film transfer coating, nozzle coating, air brush coating, curtain coating, and dry coating.

The wetting of the web is necessary, for example, to equalize the moisture profile of the web or the "··" stress differences during drying or finishing. Wetting is particularly used in calendering to control the formability of the web. Humidity gradient calender: * ·: 25 coils are applied to the dry web just prior to calendering treatment.

In present-day wetting methods, the web is wetted by spraying with water or water vapor. Water can be sprayed directly by pressure or by '... · compressed air as a water mist. A problem with these methods may be: '1': indication of spray irregularity and nozzle adjustment and maintenance.

Patent publication FI 931021 discloses a method and apparatus in which a paper web is moistened to reduce the glass transition temperature of the paper immediately before the calender nip. In the wetting process, steam is fed to the paper roll surface of the heated roller side. Further, the web is brought into contact with the roll to be heated even before it enters the calender nip. This method is workable in itself, but its technical implementation is complex. It is also technically difficult to adjust.

SUMMARY OF THE INVENTION A method and apparatus have now been invented in which a substance can be transferred into a web in a particularly simple and efficient manner. To achieve this object, the invention is characterized by the features set forth in the independent claims. Other claims disclose some preferred embodiments of the invention.

According to the invention, 10 porous materials are applied to a porous material, whereupon the web and porous material are contacted in a transfer zone where the material is transferred from the porous material to the web.

In the transfer zone, the material is transferred to the web by squeezing a porous web. The porous web is suitably compressible material. Compressibility can be achieved by using a suitable structural material or by making a substantially non-compressible structural material into a compressible structure.

The web may be, for example, paper (including cartons), fibreboard or the raw material used to make them.

- :. The invention provides the advantage that the substance can be dispensed uniformly or accurately in the desired distribution, including in the transverse direction, into the porous web, thereby achieving a good profiling accuracy. Dispensing to the porous track is easier when it is • · *

Sleep and smoother compared to the web. The process can also be considered an advantage; * ', agility (high throughput) and versatile control capabilities.

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The drawings .., The accompanying drawings form part of one embodiment of some embodiments of the invention; '25 detailed descriptions.

';, Figure 1 schematically illustrates the transfer of material to the web in a nip with a single porous bar. 1 dalla.

Figure 2 shows the transfer of material to the web in a nip between two porous paths.

Figure 3 shows the transfer of material into a web in the form of two flexible webs or roll thereof between two porous webs.

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Figure 4 illustrates the transfer of material from a porous path using centrifugal force. Figure 5 shows the transfer of material from a porous path between two belts.

Detailed Description of the Invention

In this context, the term "web" refers in particular to paper formed from paper, cardboard or their pulps. Specifically, the substance to be transferred refers to the material to be applied to the web during the manufacturing process (including post-treatment). The substance may be in the form of, for example, a liquid, such as a solution, or a mixture of a liquid and a solid, such as a slurry, or a dispersion or a solid alone. For example, the agent may be a wetting agent, such as water, or an adhesive, such as a surface or mass adhesive, or a coating agent, such as a coating paste or a dry coating agent, or an agent affecting web properties such as fiber structure, particularly reinforcing, or opaque.

According to the invention, a porous web, such as a blanket or wire, is arranged to travel in contact with the paper web through a transfer zone. 15 portions are applied to the porous path prior to introducing the porous path into the transfer zone. In the transfer belt zone, the porous path may be particularly above or below the web. In the transfer zone, the porous path or web is preferably supported by support surfaces for at least a portion of the path, preferably on either side. Rollers, such as soft or hard rolls, belted structures, such as endless rotation ·; *; 20 belted structures, or static structures. In the transfer zone, the porous web and web are pressed against each other.

;. In the transfer zone, the porous web comes into contact with the web so that the material is transferred to the web by various mechanisms and driving forces. An important driving force is the hydrostatic pressure difference caused by the compression of the porous web in the transfer zone, which drives the material out of the porous web. naan. The contact pressure caused by the compression forces improves the porous materials: t <; ' contact, which may otherwise be incomplete. Also, capillary forces on the web, which increase as the web compresses and the pores shrink, promote the transfer of material * * to the web pores. If it is desired to maximize the efficiency of the transfer process, it is probably advantageous to add the substance to the porous web so that its concentration is as close as possible to the saturation concentration. After the transfer zone, the web and ';' 'The porous path is best separated as quickly as possible so that the substance-. 'Time to move back to the porous track.

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The operation of the transfer zone may be based, for example, on a pressure difference such as a total or partial pressure difference, a concentration difference, the utilization of capillary forces, the accelerating forces of the material to be transferred, such as centrifugal force or gravity, or electrostatic attraction.

It is also possible to remove excess dosing material from the porous path prior to the transfer zone to achieve better dosing accuracy in the web contact itself. It may also be necessary to remove any excess material or impurities prior to application of the material to the porous web. Removal may be performed in one or more removal zones. They may be located in the direction of travel of the porous path before or after the 10 application zones. Material transfer in the removal zones may be based on the same phenomena as in the transfer zone.

The material to be transferred may be applied to the porous web, for example, using film transfer or pond pressing technology, circulating the porous web in a mobile material filled pool, spraying, brushing, scattering, gravity draining, or contacting from one surface, e.g. The process of transferring the application zone can be enhanced by the use of electrostatic charges.

The substance to be added may be water in particular. The material to be added may also be bulk or surface. an adhesive, for example a starch blend, a coating agent, for example a coating paste 20 or a dry coating agent, a fiber reinforcing agent for the web, for example a crosslinking polymer, or other end-use enhancing agent.

: ": The porous orbit can be in infinite rotation. This has the advantage of, among other things, simplicity of the structure,,: The material loss is also reduced and the system is easy ···. Bomb to automate and equip with the necessary measuring and control devices.

The transfer of material from the porous web to the web is carried out in the transfer zone. The transfer zone may consist of a contact zone between the paper and the porous web, in which either the web or the porous web, or both, are supported by support surfaces. The support surfaces may also have the function of placing the web and porous web in sufficient compression contact with the transfer process. for your success.

: 30 The supporting surfaces may consist of conventional rotary or static structures used in the manufacture of paper or board. In particular, the nip forming rollers may serve as a support surface. Possible solutions are, for example, a hard nip (two hard rolls), a soft nip (soft and hard roll) and a long nip (so-called belt or shoe nip).

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The support surface may also be, for example, a drying cylinder, a Yankee drying cylinder or a press roll.

The supporting surface may also be a belt, in particular a metal belt or a polymer belt, a wire or a drying wire. Furthermore, the belt-bearing support surfaces may be supported, for example, by a roller, another belt, a hydraulic shoe or a static support structure such as a hydraulic support zone.

The support surface may also be a non-rotating structure, such as a sliding shoe or a rod or the like beam. In particular, a hydraulically lubricated sliding zone can be used in a manner similar to, for example, a shoe calender.

10 A porous belt specially designed for this purpose may serve as a porous web. The operation of the porous web can also be combined with the operation of the wires and belts already in the manufacturing line. One example of this is the drying wire, which is also used as a porous web.

The porous web is then suitably compressible material. Compressibility 15 may be achieved by using a suitable structural material or by making a substantially non-compressible structural material.

The porous web may be, for example, a loose, porous belt that rotates and adapts loosely to the surface of the support surface.

The porous web may be a porous layer integral with the surface of the support surface. In this 20 alternative it replaces any coating on the support surface. In particular, a conventional circular roller or an endless belt may be coated with a porous layer.

In the transfer zone, either a single porous path in contact with only one surface of the web or two porous paths in contact with both sides of the web can be used. In the latter case, both can be moved from the porous paths. . 25 same substance or different substances from different tracks.

For example, the web may be in contact with a porous web, either on one side only: or on both sides.

'; · 'The porous web may be positioned to pass, for example, above or below the web. From the porous path above, the substance is also transferred to the web by gravity »»

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»T 115850 6 under the influence of man. Such a solution can be used, for example, in a separate transfer nipple.

The transfer zone may be supported on support surfaces either on one side or on both sides. An example of a solution supported on both sides is a nip contact. The pre-5 sign of just one side of the supported solution is, like a dryer wire, a porous web that presses paper against the dryer cylinder. In this case, the tension of the porous path provides the compression effect required in the transfer zone.

The transfer zone may be unreadable for a portion of the distance supported by the supporting surfaces.

The porous web (s), support surface (s), and web may be arranged differently in contact with the transfer zone. Examples are: 1. Surface - porous web - web - porous web - support surface 2. Surface - web - porous web - support surface 3. Support surface - web - porous web 15 4. Support surface - porous web - web - porous web 5. Support surface - porous web - web

The operation of the application zone may be based on the same mechanisms and driving forces as the transfer zone.

Material transfer in the transfer zone can be enhanced by providing a porous path and! A web in contact therewith to travel along a curved path, for example a roll; following the outer surface of the lan. When the porous web is inside, the centrifugal force exerted on the material phase it carries drives the material toward the outer web.

The transfer can also be enhanced by heating the porous web and the material to be transferred therein. The heating may take place, for example, on the supporting surface of the contact, 25 with or through direct action (eg microwaves) on the porous and movable ·. material. The phenomenon of vaporization in the porous path as a result of heating and transfer is similar to that of an impulse press. The gas phase formed during heating forces the material to be transferred to move very efficiently in the direction of the web. If the substance to be transferred is water, the temperature should be sufficient for evaporation.

. ··. 30 preferably 100-350 CC. Heating also lowers the viscosity of the material to be transferred, thereby increasing its fluidity and facilitating material transfer.

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The transfer can also be enhanced by blowing gas, for example, air through a support surface (e.g., a roll shell, or belt) to the porous web, where it further pushes the article to be moved with a differential pressure towards the web. In particular, the material to be blown may be the same as the material to be transferred to the web itself. In this embodiment of the invention, the support surface, for example the roll, must of course be porous or perforated itself. For example, the roll may resemble a suction roll, in which, instead of sucking, the punch is blown. Particularly in this embodiment of the invention, it is possible to blow hot steam through the support surface into the compression zone so that no bypass leakage occurs. In this case, it is possible to pressurize the compression zone region so that the fluff condensates at a temperature higher than 10,100 = C. This provides the advantage that the latent heat of the condensing steam is better utilized, whereby the heating effect of the condensate is sufficient to effectively heat the web up to higher temperatures.

In the transfer zone, the amount of vapor in the transition material, such as water vapor, can be dimensioned such that the heating effect of the transition material and the increase in pressure helps the plastics to ring the fibers. This can, for example, promote calendering. Typically, the amounts of steam applied can reach up to 10 g / m2.

Material transfer in the transfer zone can also be enhanced by cooling the porous web and / or supporting surface in contact with the web. The transfer of the substance can be particularly effective when the transfer material is heated and huokoisradan side with respect to '· huokoisrataa the opposite side of the pulp web 20 or the support surface is cooled.

• »'; Material transfer to or from the porous web and its enhancement outside the transfer zone, particularly in the application zone or removal zone, may be based on the same principles as in the transfer zone. In particular, the difference between total and partial pressure, concentration difference, electrostatic forces can be utilized. capillary effect and mass inertia. These effects are obtained, for example, by blowing, compressing porous material, heating; ·,: With or by cooling and reversing (acceleration).

The transfer zone, such as the transfer nipple, may be located at a convenient point in the actual manufacturing line, for example, on the press portion of the paper or board machine and on the retractor / * 30. In particular, a solution can be used which dispenses the substance to be moved, · · ·, pores and presses it against the drying cylinder.

'* The transfer zone may also be in an on-line or off-line post-processing line. The transfer nip can be combined with a calender nip. Then the substance, in this case mainly water.

115850 8 transfer and calendering process can be combined in the same nip or in successive nipples (multi nip).

The whole of the transfer process can be controlled, for example, by controlling the amount of material to be applied either in the transverse direction (CD direction) or in the machine-5 direction (MD direction). Subprocesses of the transfer process may be affected by application in the zone, removal in the zone, or the transfer zone. For example, if it is desired to adjust the amount of substance to be transferred in the transverse direction, the driving forces of the transfer phenomenon in the various subprocesses in the application, removal or transfer zone may be affected. For example, profiling of the compression pressure 10 in the transfer zone or profiling of the blows used.

Similarly, profiling can be accomplished by controlling the transfer phenomena of the application or removal zone. The purpose here is mainly to control the concentration of the substance to be transferred in the porous path before it enters the transfer zone. This can be done by influencing the prevailing driving forces.

15 Machine control of the process, as a function of time, according to the driving situation is also important. This can be accomplished in principle by the same means as the profiling described above by influencing the prevailing driving forces.

The necessary actuators and functions are connected to control the · process of the measuring and control system.

Detailed Description of Some Embodiments of the Invention Some embodiments of the invention will now be described in detail with reference to the accompanying drawings.

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As shown in Figure 1, the paper web 1 is guided with a porous belt 2 by a compression. . contact to the transfer zone (nip) between rollers 3 and 4 A. The porous belt 25 is of resilient material and has been impregnated with a transfer agent 5 in application zone B. The hydrostatic content of the material in the paper prior to the transfer zone is: · less than that of the belt and thus tends to transfer to the paper. In the transfer zone, the belt can be significantly compressed, thereby effectively transferring the material to the paper. The belt compression also increases the nip length, which increases the distance and time available for material transfer. After the transfer zone, the belt and the web are immediately separated so that material cannot be transferred from the web back to the belt. After the transfer zone, as the compression is relieved, the belt 115850 9 returns to its specific thickness. The nip can also pinch the web. The material and impurities remaining on the belt can be further removed in the removal zone C if necessary.

In application zone B, substance 5 is applied to the belt 2 here by spraying nozzles 6. The nozzles are located in a transverse array of straps such that a uniform jet pattern is formed on the sleeve. If necessary, the nozzle group can be used for profiling, in particular by applying more material to the edges of the belt. Thus, for example, the transverse moisture distribution of the web can be adjusted as evenly as possible.

In the exhaust zone C, material and impurities can be removed from the belt, for example, by blowing air with blowers 7.

In the transfer zone A, rolls 3 and 4 support the paper web 1. After the transfer, the web is unsupported for some distance and can be led, for example, to another unit where material is transferred to the web, for example from the opposite side of the web.

In the transfer zone A, the paper web 1 can also be compressed as long as the pressure is sufficient. The Jär-15 arrangement can thus be used, for example, for calendering. In this case, the paper web side roll 4 may be in particular a hard surface roll, a belt side roll 3 in particular a heated roll and a water transfer material.

2, the paper web 1 is introduced into a nip between the rollers 3 and 4.1. -. for zone A between the two straps 2.1 and 2.2. Grafting agents have been applied to the straps. As the belts are compressed in the transfer zone, material is transferred to the web. Here; ·; in the arrangement, different substances can also be conveyed from different sides of the web simultaneously.

; In this arrangement, efficient material transfer can be achieved with as little compression as possible.

Also in the arrangement of Figure 3, the paper web 1 is introduced into the transfer zone 1. : 25 A between two straps 2.1 and 2.2. Here, rolls 3.1 and 4.1 are coated with a flexible but • non-porous coating 8. The coating is compressed in the nip, thereby further increasing the length of the nip and thus the material transfer distance.

; In the arrangement of Figure 4, the paper web 1 is guided to the roll applicator station B between the porous belt 2.3 and the pivot roll 9. On the pivoting roll belt, a substance (e.g., coating material) 5 to be carried by the lifting roller 10 is applied to the outer surface of the roller roller. The applied layer of material is adjusted by a leveler 11. The material moves from the belt. To enhance material transfer, the web and belt are guided to a transfer roll 115850 belt 12 against the roll surface. The centrifugal force then drives the material from the belt to Taina. After the transfer roll, the web and belt are separated.

In the arrangement of Fig. 5, two straps 13 and 14 are rotated about the support rollers, which run for a distance parallel to each other so that a transfer zone A is formed between them. The straps may be, for example, metal or polymer straps. In addition, a porous belt 2.4 is arranged around the lower belt, to which, prior to the transfer zone, the transferable substance 5 is applied in the application zone B. When the web 1 to be treated is passed through the transfer zone, material from the porous belt is absorbed therein. The material is discharged from the belt with a discharge zone 10 tongue C.

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Claims (23)

A method of transferring a substance to a web (1), wherein the substance (5) to be transferred is applied to a porous route (2; 2.1; 2.2; 2.3; 2.4) of porous material, followed by the web (1) and the the porous route is contacted in a transfer zone (a), the substance being transferred from the porous route to the web, characterized in that the porous route (2; 2.1; 2.2; 2.3; 2.4) consists of compressible material. Method according to claim 1, characterized in that the porous route (2; 2.1; 2.2; 2.3; 2.4) is in endless circulation. 10 Process according to claim 1 or 2, characterized in that the substance (5) to be transferred is liquid, such as a solution, or a mixture of liquid and solid, such as a suspension, or a dispersion or solid only. Method according to any of the preceding claims, characterized in that the substance (5) to be transferred is wetting agent, such as the water, or adhesive, such as surface or pulp adhesive, or a coating agent, such as coating paste or dry coating agent, or a substance which affects the properties of the web, such as a substance that changes the fiber structure, especially reinforcing, or a substance that changes the optical properties of the web. 20 Method according to any of the preceding claims, characterized in that the web (1) and the porous route (2; 2.1; 2.2; 2.3; 2.4) are contacted in a transfer zone,: (A), where the porous route is in contact with the track only on one side of the track. , i 25 Method according to any of claims 1-4, characterized in that the web (1): and the porous route (2.1; 2.2) are contacted in a transfer zone (A), where the web is in contact with the porous route on both sides. . 'W Method according to any of the preceding claims, characterized in that the porous route (2; 2.1; 2.2; 2.3; 2.4) or the web (1) is supported with support surfaces (3; 4; 12; 13, v, 14), preferably on both sides, at least over part of the transfer zone (A). Method according to claim 7, characterized in that the support surface is a roller (3; 4; 4.1; 12), such as a core or a soft roller, or a belt-like structure (13, 14), such as a belt-like structure in endless orbit, or a static structure, such as a hydraulic support zone. 115850 Method according to any of the preceding claims, characterized in that the function of the transmission zone (A) is based on differential pressure, such as full pressure or partial pressure difference, or concentration difference, or utilization of capillary forces or electrostatic forces, or the accelerating forces of the of the substance to be transferred, such as centrifugal force or gravity. Method according to claim 9, characterized in that the function of the transfer zone (A) is based on differential pressure or concentration difference, which is achieved by heating and / or cooling. Method according to any preceding claim, characterized in that the blank (5) to be transferred is applied to the porous route (2; 2.1; 2.2; 2.3; 2.4) in an application zone (B), the function of which is based on differential pressure, such as full pressure or partial pressure difference, or concentration difference, or utilization of capillary or electrostatic forces, or acceleration forces of the mass of the substance to be transmitted, such as gravity. Method according to claim 11, characterized in that in the application zone (B) the blank (5) is blown on the porous route, in particular through it. A method according to any preceding claim, characterized in that after 'F; the transfer zone (A), the substance is removed from the porous route (2; 2.1; 2.2; 2.3; 2.4) i. *, a removal zone (C), whose function is based on differential pressure, such as full-pressure • *. Or partial pressure differential, or concentration difference, or utilization of capillary. forces or accelerating forces of the mass of the substance to be transmitted, such as centrifugal force or gravity. Method according to any of the preceding claims, characterized in that the supporting surface (3; 4.1; 12; 13) facing the porous route (2; 2.1; 2.2; 2.3; 2.4) is heated to streamline substance transfer in the transfer zone (A), e.g. with contact heating, or by condensing meadow, or by heating with one. · · ·. infrared heaters, microwaves or with an electromagnetic field of RF frequency. t 1 t '·' '35 Method according to any of the preceding claims, characterized in that the * itself: the porous route (2; 2.1; 2.2; 2.3; 2.4) is heated to effect the substance transfer in the transfer zone (A), e.g. with contact heating, or by condensing meadow, or by heating with an infrared heater, microwaves or „115850 with an electromagnetic fault at RF frequency. Method according to any one of the preceding claims, characterized in that the support surface (3; 4.1; 12) is cooled down to effect the transfer of substance in the transfer zone 5 (A). Method according to any one of the preceding claims, characterized in that the porous route (2; 2.1; 2.2; 2.3; 2.4) itself is cooled down to effect the substance transfer in the transfer zone (A). 10 Method according to any of the preceding claims, characterized in that the web (1) consists of paper, a wood fiber board or of raw material used in their manufacture. 15 Method according to any of the preceding claims, characterized in that the content of the substance (5) to be transmitted is controlled in the transverse direction, in particular by regulating the forces controlling the transfer effect, such as the compression pressure or temperature, especially in the transfer zone (A). A method according to any of the preceding claims, characterized in that the content of the substance (5) to be transferred is controlled in the machine direction. • · · »* * · 21. Plant for transferring the substance to the web (1), wherein the plant is present; a transfer zone (A), where the web (1) is contacted with a porous route (2; 2.1; * ··. 2.2; 2.3; 2.4) consisting of porous material, on which the substance (5) is to be transferred has been applied, characterized in that the porous route (2; 2.1; 2.2; 2.3; 2.4) is made of compressible material. »» · An installation according to claim 21, characterized in that it comprises means for controlling the content of the substance (5) to be transmitted in the transverse direction, in particular by regulating the forces controlling the transfer effect, such as compression pressure, temperature. , concentration, pressure in the gas or liquid phase, electrostatic pulling, · · ·, force or blowing intensity, in the transfer zone (A). * t »· '' 35 Plant according to claim 22 or 23, characterized in that it comprises means for controlling the content of the substance (5) to be transmitted in the machine direction as a function of time.