DE112005000532T5 - Method and device for applying a coating and / or processing agent to a fibrous web - Google Patents

Abstract

method to transfer or applying a coating and / or a processing agent on a paper / cardboard web (W) with a processing device, which has a bearing or guide surface, formed by at least one treatment element (5, 2, 15) is, wherein the web to be processed (W) in a touching Contact with the same passed being, being a contact surface at least one of the treatment elements (2, 5, 15) of the processing device as transfer area is used, which with one to the web (W) before touching the transfer surface to be transferred by train Means (13) is supplied, characterized in that the transfer surface for Preheating the before the transfer of the same heated to a press contact with the web to be transferred means becomes.

Description

The The invention relates to a method and a device for applying a coating and / or processing agent on a paper / paperboard web with a processing device, which with at least one Contact zone is provided, which by a web treatment element, such as a belt or a roller or the like, and formed by the web itself, and in which the agent transferred in a first step to the treatment element becomes, from which the agent in a second process step on a surface the fibrous web transmits by means of a contact within the treatment zone.

In various known and customary in the art used coating and Oberflächenleimungsverfahren the applied agent directly on the surface of a paper or paperboard web applied. During spray coating For example, the coating is applied directly as a fine mist sprayed a train, while during curtain coating and during jet coating of the coating slip as a thin "curtain" or movie directly is drizzling on a train. The prior art also discloses coating or coating method known in which the coating agent first on a surface is applied, for example, on the surface of an applicator roll or of a transfer belt, these examples blasting (Applicator roll) and film coating (applicator roll).

One common feature of the above-mentioned methods is that the processes are so-called wet coating processes. The applied Agent is applied to a fibrous web as a moist suspension or a slurry is applied and the coated fibrous web must be downstream of the Application are dried. On the other side is in a so-called dry coating process that on a Fiber web applied agent in a dry, powdery form. The application is accomplished by electrically charging the feed material particles and by maneuvering the flow of material in the application process and by the Binding to a transfer surface performed by means of an electric field. The applied material layer must be tied additionally become what by means of a hot Press application gap is achieved. For the coated fiber web however, no drying is needed.

It is a general object of the present invention, an improved and an improved method for applying an agent to a To create fibrous web. An important task is one to make consistent dispensing of an agent to be applied and to facilitate, in a very advantageous manner according to the invention This is accomplished by having the agent first with a high accuracy on a flat and smooth storage surface, such as a Roller or belt, is issued, from which it below get to a fiber web.

It is a second important task, applying and connecting a applied agent with the surface of a fibrous web by increasing the To improve the temperature of an applied agent, so that the agent softer, more fluid and penetrates better into the fiber web after application. consequently It is an object of the invention, a simple yet effective technical solution for heating one in connection with an application to be transferred To create by means. A third important task is the adhesion of a on a fiber web applying agent by creating a Improve connection process, in which the applied Medium is in press contact with the fibrous web to a To obtain sufficient duration to the heated and plasticized agent enough To give time, to flow in a proper way and penetrate into the pores of the fiber web.

Around To solve the above tasks is a method of transmission or applying a coating and / or a processing agent on a paper / cardboard web with a processing device which has a bearing or guide surface, which is formed by at least one treatment element, wherein the web to be processed (W) in a touching contact with the same past being, being a contact surface at least one of the treatment elements of the processing device as transfer area is used, which with a to the web before touching the transfer surface to be transferred by train Medium is supplied. Characterized in that the transfer surface for Preheating the before the transfer of the same heated to a press contact with the web to be transferred means becomes.

An apparatus of the invention for transferring a coating and / or processing agent to a paper / paperboard web, the apparatus having at least one guide surface formed by treatment elements, the web being in a nip or roll therewith is contacted in a treatment zone, wherein one of the abutment surfaces of at least one of the treatment elements of the device is adapted to act as a transfer surface which is supplied with an agent to be transferred to the web prior to contacting the transfer surface with the web, again characterized in that the transfer surface is so is formed so that it can be heated to preheat the same before being transferred to a press contact with the web to be transferred means.

at a method according to the invention the funds to be applied first Applied to a moving transfer surface, which on a Transfer zone for a contact with a fiber web is passed, wherein the applied means transfers from the transfer surface to a surface of the fibrous web. Consequently the transfer zone is formed by a contact region which both the transfer area as well as the fiber web listened to and which an agent to be applied is supplied, which by the transfer surface is borne, and from which the fiber web is issued, which on their surface the applied agent carries. The transfer surface In particular, a roller, a belt or a sieve or a other continuous area which is in contact with a fibrous web. In addition, can the transfer zone on a roll, a sieve or a belt at the same time have two sides of a fibrous web in contact with the fibrous web or not, resulting in a press zone or a nip the case is that of a pair of rollers, a roller and a roller a set of belt loops or two opposite ones Belt loops is formed.

Consequently is used in a method according to the invention, the surface, which makes contact with a fibrous web in the transfer zone, as a transfer area used to which the to be transmitted Means is applied in such a way that they within the transfer zone, finally in contact with the Fiber web is brought and goes on the latter. The transfer area is so heated up that it applied to the fiber web to be transferred Means even before winding in contact with the fibrous web heats up and thus the to be transmitted Means already during a transition on the surface the fiber web was heated, which takes place in the transfer zone. By means of preheating flows the so transferring Medium and penetrates more easily into the pores of a fiber web and has a stronger one Adherence to the fiber web. The final connection with the surface of the Fiber web and the densification of the transferred material layer should in the transfer nip in response to heat and Compression pressure take place.

A solution The invention is particularly advantageous with reference to the Dry coat, because the applied, dry coating even heats up before a connection nip, the only function the for the nip remains, in principle, the compression of the applied Means, whereby the connecting nip dimensionally smaller may fail, especially from the point of view of heat transfer considered.

A solution the invention is also for the application of other than dry coating agents suitable. The to be transferred Agent may be made of a material in either the liquid or solid state or consist of a mixture of agents in this state, such as a mud or a suspension. Furthermore, can the one to be transmitted Means a material consisting of small, solid particles, such as a powder or a flour, which in a liquid or gaseous Phase is mixed. In particular, the agent to be transferred may be a coating material be which for the brushing of a fibrous web is used, or a processing means for one Fibrous web, such as a sizing agent or a solution-like one Chemical, which is used to the properties of a fiber web to improve water used for wetting a web or a mixture of at least two of the above agents.

The The invention will now be described with reference to the attached drawings described in more detail, in which:

1 schematically shows a solution of the invention, which is embodied in connection with a metal belt processing device,

2 schematically shows a second solution of the invention, which is also embodied in connection with a metal belt processing device,

3 schematically shows a third solution of the invention in connection with a nip,

4 schematically shows a fourth solution of the invention, which is used in conjunction with a roller,

5 schematically shows a fifth solution of the invention, and

6 schematically shows a sixth solution of the invention.

The Invention will now be described by way of example with reference to FIG on their different embodiments described.

1 FIG. 12 illustrates a mechanical solution of the invention which is an endless metal belt loop 2 as well as a counter element 5 which serves as its outer bearing surface, wherein a Fiber web W is passed through a contact therebetween. The belt 2 and the roller 5 form between them an extended treatment zone N, the compression pressure effect applied to the fibrous web, both by a tension of the belt 2 as well as by the load of a possible additional carrier roll 4 can be regulated within the belt loop.

In the embodiment of 1 becomes a means to be transferred 13 issued on at least one bearing surface, either by means of an applicator 11 on the belt 2 or by means of an applicator 11 ' on the surface of the roller 5 , The application can also be carried out simultaneously on both surfaces.

In the embodiment of 1 is at least one of the bearing surfaces, either the metal belt 2 or the roller 5 , designed so that it can be heated. The metal belt can be used with a separate heater 6 , such as an induction heater, an infrared heater or a gas burner are heated. The heater can also be based on resistance heating. The heating can also be effected by means of heated support rollers. The roller 5 may be configured so that it can be heated, for example by means of conventional heating methods for thermo rolls. If necessary, the bearing surfaces are close to them with doctor blades or other such cleaning systems 7 . 7 ' to prepare the bearing surfaces for the next cycle in an endless circulation.

The in the embodiment of 1 illustrated applicators 11 . 11 ' may be similar to those used in a dry coating process wherein the agent flowing out of the applicator is charged with an electrode assembly (not shown) disposed proximate to the stream, and wherein the metal belt 2 and / or the roller 5 further provided with a grounding electrode (not shown). Thus, the particles of the thus transferring agent flowing out of the applicator are charged with a potential difference with respect to the transfer surface 2 . 5 is sufficient for them to get to the transfer surface. While in contact with the heated transfer surface, such particles heat up before they come in contact with the fibrous web W. The particles 13a are preferably adapted to make contact with the fibrous web in a sufficiently long treatment zone between the belt and the roll 5 so that the fibrous web in the treatment zone is subjected to a heating and pressure effect, by means of which the agent to be transferred permanently bonds to the surface of the fibrous web.

In In a particularly advantageous case, the agent to be transferred has a dry, powdery material, which on pigment or dry barrier coating is used, preferably a mixture of pigments and sizing agents or adhesives or polymers. Instead of a particulate, dry Coating agent, it is also possible to use a material in the Form of a solution, a fine spray, a mud, a paste or another to apply moist mixture.

In addition to a coating pigment and binder mixture, the material may e.g. As a sizing agent, a solution-type chemical, water or the like. In addition to an above with reference to 1 described method applying an electric field, the outputting of an agent to be transferred to a transfer surface can also be effected by other known principles, such as by brushing, spraying, trickling or by indirect contact bonding, and in particular by methods which apply these principles, such as spray coating, trowel coating, jet coating, roller coating, etc.

The transfer surface is preferably downstream of a transfer nip using an actuator 7 . 7 ' doctored or cleaned before another dose of the agent to be transferred is dispensed. An adhesion preventive chemical may be applied to the transfer surface as a cycle progresses.

2 represents an embodiment, which in principle similar to that in 1 is shown, however, the bearing surface has a second belt loop 2 ' instead of the roller 5 on. Other important principles are the same as those of 1 ,

3 shows an embodiment of the invention, in which two rolls 5 . 5 ' between them forming a nip or a treatment zone for passing a fiber web W. The operation of the treatment zone can be controlled by regulating the nip pressure and the temperature of the rolls.

In this embodiment, the supplied agent is by means of applicators 11 . 11 ' on the outer surfaces of the rollers 5 . 5 ' issued, which work as storage areas. The application can either only on one of the surfaces 5 . 5 ' or both at the same time. At least one of the bearing surfaces is heated, with the result that the applied agent heats up before it is in contact with the fibrous web W in the Transfer zone is coming. The heating of the rolls can be effected by conventional arrangements. The rollers are with the devices 7 . 7 ' cleaned before another portion of the agent is dispensed thereon.

4 represents an embodiment in which the applied agent 13 z. B. has a dry coating mixture of a pigment and binder in a particulate form in a dry, powdery state. In the exemplary embodiment of 4 is the opening of an applicator 12 with electrodes 21 for charging particles 13 provided after their exit from the applicator. A roller 15 is with a grounding electrode 10 and at the same time forms a transfer surface, which is the first target for charged particles 13a which is from the applicator 12 flow out. The roller 15 which acts as a transfer surface is then passed, together with particles present on its surface, into contact with the fiber web W for transfer of the particles to a surface of the fiber web. The contact preferably takes place in a nip N (zone II), which with a counter-roller 16 is formed, or slightly upstream of it (zone I). The roller 15 is heated, reducing the particles supplied 13 even heating up prior to contact I or II, in which the final bond occurs in response to pressure and heat applied to the web in the nip N.

5 represents a very simple embodiment of the invention, which only a heated roller 5 and a fibrous web W in contact with its outer surface. An applicator 11 is used to dispense a means to be transferred to the roll surface serving as a storage and transfer surface, at which the means to be transferred is heated and from which the means for advancing to the fiber web in a transfer zone (not shown). A contact pressure existing in the transfer zone is generated only by tensile forces F of the fibrous web, resulting in poor contact and poor heat transfer. For this reason, it is an object to maximize a cover length, and the method is best suited for slow running speed and thick grades (paperboard). However, because it is first applied to a heated roll surface, the agent heats up even before a transfer zone and there is no need for a special good heat transfer contact. However, it is still advantageous in this embodiment, for example in the case of a dry coating, to use agents which have a glass transition temperature Tg which is low, e.g. B. in the order of 20-100 ° C.

6 shows an embodiment in which the means to be applied by the use of an electric field on a fiber web W with an applicator 12 is applied. The applicator 12 has one with electrodes 21 for charging particles 13 after its exit from the applicator provided opening. A roller 15 is with a grounding electrode 10 and simultaneously forms a transfer surface, which is the first target for charged particles 13a which is from the applicator 12 flow out. The roller 15 which acts as a transfer surface is then forwarded together with particles present on its surface to contact with the fibrous web W for discharging the particles on a surface of the fibrous web. The storage area, in this case a thermo roll 15 is heated and thus the applied agent heats up before it comes into contact with the fibrous web W in the transfer zone. A pressure present in the contact is also generated exclusively by a web tension in this embodiment. Because the con tact pressure is very low, resulting in a low heat transfer, it is advantageous in this embodiment to use a transfer agent, for example a dry coating, the treatment of which can be carried out at a low temperature. It is particularly advantageous to use a dry coating agent which has a glass transition temperature Tg which is low, e.g. B. in the order of 20-100 ° C.

The invention has been described by way of example with reference to FIGS 1 - 6 described. With respect to the belt loop, reference is made to a metal belt solution in which a steel belt is particularly useful. However, the use of other metal straps and even non-metallic straps and straps is possible. For example, it is conceivable to use, in suitable cases, drying screens or other fiber-reinforced polymer screens.

The Invention is particularly suitable for coating, for surface sizing and for wetting fibrous webs of paper and paperboard, which are in Connection with a production line are applied, and indeed both as an online and offline solution. The invention finds also in the manufacture of other web-like products, such as for example, coated fiberboard, application.

Summary

Method and device for applying a coating and / or processing agent to a fibrous web

The invention relates to a method and a Device for transferring a coating and / or a processing agent onto a paper / cardboard web (W) having a processing device which has a contact or guide surface which is guided by at least one treatment element ( 5 . 2 ), the web to be processed (W) being in contact therewith. The method includes that the contact surface of at least one of the treatment elements ( 2 . 5 ) of the processing device is used as a transfer surface which has to be transferred with a means (to be transferred to the web (W) before touching the transfer surface with the web ( 13 ) is supplied. The transfer surface is heated to preheat the agent to be transferred to press contact with the fibrous web prior to transferring.

Claims (19)

Method for transferring a coating and / or a processing agent onto a paper / cardboard web (W) having a processing device which has a contact or guide surface which is guided through at least one treatment element ( 5 . 2 . 15 ) is formed, wherein the web to be processed (W) is guided in a touching contact with the same, wherein a contact surface of at least one of the treatment elements ( 2 . 5 . 15 ) of the processing device is used as a transfer surface, which has to be transferred to the web (W) before contacting the transfer surface with the web ( 13 ), characterized in that the transfer surface is heated to preheat the agent to be transferred to a press contact with the web prior to transfer. Method according to claim 1, characterized in that that the transfer area in a nip or treatment zone (N) with the fibrous web is brought into contact. Method according to claim 1 or 2, characterized that in the process of applying to the transfer surface the to be transferred Medium in a moist, pasty consistency in the form a sludge or a suspension or a solution or of a spray. Method according to claim 3, characterized that to be transferred to the fibrous web Means water or a water-soluble one Has chemical. Method according to claim 3 or 4, characterized that the application method was selected from the group which consists of the following: Film coating, spray coating, Curtain painting and casting. Method according to claim 1 or 2, characterized that in the process of applying to the transfer surface the to be transferred Agent is in a powdered or powdered form. Method according to claim 6, characterized that to be transferred to the fibrous web Agent has a dry coating material. A method according to claim 6 or 7, characterized in that the agent to be transferred is in the form of powder or in another particle form which is transferred to a transfer surface using an electrically charged field, the transfer surface acting as an electrode and the Path or its surroundings of a flow carrying the means to be transferred with at least one second electrode ( 11 ) so that the flowing material particles are charged with a charge potential which is sufficient with respect to the electrode formed by the transfer surface to cause the charged particles ( 13a ) get to the transfer area. Method according to one of claims 1 to 8, characterized in that the processing device a metal belt loop ( 2 ), which is intended to be at least one support element ( 3 ) and at least one counter element ( 5 ) outside the belt loop for establishing an extended treatment zone for the fiber web together with the belt loop. Method according to one of claims 1 to 8, characterized that the processing device one between two opposite Roll formed trained nip. Method according to one of claims 1 to 8, characterized in that the processing device has a contact area, formed by a contact between a roller and the fiber web is. Method according to one of claims 1 to 11, characterized that a medium is transferred simultaneously to both surfaces of the fibrous web becomes. Method according to one of claims 1 to 11, characterized that a means only transferred to a surface of the fibrous web becomes. Method according to one of the preceding claims, characterized in that the processing device is not used only for binding a means to be transferred to the fibrous web but also for the calendering treatment of a fibrous web in a nip or a treatment zone. Device for transferring a coating and / or a processing agent onto a paper / cardboard web (W), wherein the device has at least one contact or guide surface which is guided by treatment elements ( 5 . 2 ,), wherein the web is contacted with the same in a nip or in a treatment zone (N), wherein one of the abutment surfaces of at least one of the treatment elements ( 2 . 5 ; 2 '; 5 '; 15 ) of the device is designed to act as a transfer surface which has to be transferred with a means to be transferred to the web (W) before contacting the transfer surface ( 13 ) is supplied, characterized in that the transfer surface is formed so that it can be heated to preheat the same before being transferred to a press contact with the web to be transferred means. Device according to claim 15, characterized in that it comprises a metal belt loop ( 2 ), which is intended to be at least one support element ( 3 ) and at least one counter element ( 5 ) outside the belt loop for establishing an extended treatment zone for the fiber web together with the belt loop. Device according to claim 15, characterized in that it comprises a roller (2) lying opposite one another 5 . 5 '; 15 . 16 ) formed nip. Device according to claim 15, characterized in that it comprises a roller ( 5 ; 15 ) for bringing into contact with the fibrous web (W). Device according to one of claims 15 to 18, characterized in that the transfer surface ( 15 ) is designed to act as an electrode and that the device further comprises at least one second electrode ( 21 ), which is arranged in the path of a means to be transferred, whereby flowing material particles ( 13 ) are chargeable with a charging potential which is sufficient with respect to the electrode formed by the transfer surface to cause the charged particles ( 13a ) are transferred to the transfer surface by means of an electrically charged field.