Patent Application
20050098285
1. Field of the Invention
The invention relates to a machine for producing and treating, or for treating a material web, and, more particularly, to a machine for producing and/or treating paper or paper board.
2. Description of the Related Art
Some papermaking machines permit the production and treatment, including application of an application medium to at least one side of the material web, in what is known as an online operation. In machines of this type, only contacting application apparatuses, such as coating units are conventionally used as the application apparatus.
Other machines may be used for the treatment, including the application of an application medium to at least one side of the material web, in what is known as an offline operation. Machines of this type include coating or application machines separate from a machine for producing the material web, to which the material web to be treated is generally fed in the form of material web reels. Within machines of this type, both contacting application apparatuses, such as coating units, and contactless application apparatuses, such as contactless coating units are used as application apparatuses.
Contacting application apparatuses can be a problem, inasmuch as the performance (runnability) and average operating times between operating interruptions can be impaired as a result of the contacting application or coating. Thus, there is an increased risk of a web break in the application unit resulting in the entire production line coming to a standstill.
As compared with an online operation, the offline operation has a lower volumetric efficiency in relation to the coating of the material web.
For many applications, a material quality with high smoothness and possibly gloss is desired. In order to achieve such a quality, the material web can be calendered online in a smoothing unit, possibly a two-roll soft calender, so as to be machine-finished or more highly machine-finished. Furthermore, there is a large number of material qualities which, conventionally, following the production of the material web in an appropriate machine, or following coating on a coating machine, have to be calendered offline in a further operation. Calendering exerts a substantial influence on the surface structure of the material, in particular of paper or board, and therefore both on the visual appearance and on the printability. Calendering is a very important operation for coated papers. Following coating, it provides smoothness and possibly gloss.
If the coating is carried out in an offline operation, the calendering is conventionally carried out in a separate offline process by way of a suitable smoothing machine, for example, a supercalender or soft calender, separate from the coating machine. On account of two offline processes being carried out, one after another, by way of separate machines, the result is an even lower volumetric efficiency.
What is needed in the art is a machine which has good performance and runnability and is able to provide material with a high smoothness and possibly gloss with a good volumetric efficiency.
The present invention comprises, in one form thereof, a machine having an application device with at least one contactless application unit. The unit is designed to discharge application medium in at least one free application medium jet or an application medium curtain or an application medium veil or in an application medium droplet spray and to apply it to the material web on the basis of forces and/or movement impulses imparted to the application medium and/or on the basis of a movement of the application medium induced by the force of gravity. Further, a material web smoothing device is provided along the treatment path before and/or after the application device. In addition to an application on the basis of the force of gravity, an application on the basis of electrostatic forces is to be considered.
According to one embodiment of the present invention there is a contactless application of the application medium to at least one side of the material web, in particular a contactless coating of one or both sides of the material web is made possible in an online operation or in an offline operation in the machine, in particular a papermaking machine. The material web smoothing device is integrated into the machine to ensure high smoothness and possibly gloss of the material on one side or both sides of the material web.
If the machine does not also produce the material web, that is to say the application of a coating and smoothing thereof are carried out in an offline operation, the result is a considerably increased volumetric efficiency because the smoothing device and the application apparatus are integrated into one machine, so that both a application of coating to the web and smoothing of the web are carried out in an offline process.
If the machine is also used for producing the material web that is to be treated, such as coating or smoothing procedures, in an online process, there are certain advantages. Moreover, with regard to the application of the application medium, to a certain extent the advantages of conventional contacting coating in an online operation and of a conventional contactless coating in an offline operation are obtained in combination. Specifically, on the one hand the higher volumetric efficiency of an online operation and the better runnability of the contactless coating, conventionally used only in an offline operation. According to the present invention, the high smoothness and possibly the gloss of the material are achieved by way of the material web smoothing device.
The machine has a material web smoothing device along the material web path, at least before the application device. Connecting the material web smoothing upstream of the application of the application medium is expedient and effective inasmuch as contactless application methods, in particular coating methods, largely maintain the contour of the material web surface (in this connection, one speaks of “contour coating methods”). This means that a rough contour of the material web is not evened out/or smoothed, or if it is smoothed it is only comparatively little, by the application medium. The smoother the material web is before the application of the application medium, the higher is the level of achieved product quality. In this connection, it has been shown that it is better to smooth first and then to apply the contour coating than to smooth a rough contour after the coating.
It has proven to be beneficial if the material web smoothing device is designed to calender the material web, at least on one side, in such a way that a material web roughness of no more than between 5 μm, and preferably at most 3 μm, remains. These material web roughness values preferably relate to values determined by way of the PPS method (Parker PrintSurf): roughness (PPS-10s) of ≦5 μm, or preferably ≦3 μm.
With regard to the material web smoothing device or the material web roughness achieved by the latter, these roughness values are achieved on the basis of normal operating parameters of the machine.
In addition, a material web smoothing device can also be provided along the material web path after the application apparatus. For example, in order to achieve a particularly high smoothness or a particularly high gloss. For many applications, however, a material web smoothing device before the application device will be able to ensure a sufficient smoothness or sufficient gloss.
The material web smoothing device can advantageously have a smoothing unit from the group consisting of a soft nip calender, a wide nip calender, a hard nip calender, a supercalender, a multi-nip smoothing unit (e.g. Janus), a 1-nip calender, and a 2-nip calender.
With regard to the application of the application medium, use is made of what is known as a curtain application method, also known as curtain coating. For this purpose, it is proposed that at least one contactless application unit, designed as a curtain application unit, be provided, which discharges the application medium in the form of at least a curtain or veil onto the material web. The application is, at least predominantly, on the basis of a movement of the application medium induced by the force of gravity. Alternatively, use can also be made of what is known as a spray application method, also known as a spray coating. For this purpose, at least one contactless application unit, designed as a spray application unit, is provided, which discharges the application medium in the form of an application medium droplet spray or application medium jets on the material web. The application is, at least predominantly, on the basis of movement impulses imparted to the application medium as it emerges from a nozzle arrangement.
The curtain application method is preferred over the spray application method since, on the basis of the curtain application method, a higher product quality is achieved and the curtain application method generally entails less maintenance than the spray application method.
The machine, according to the present invention, can have at least one further material web treatment device. Such a further material web treatment device can be arranged along the material web path between the material web forming device and the dewatering and drying section; or between the dewatering and drying section and the application apparatus; or between the application apparatus and the drying device; or between the drying device and the device for processing and/or picking up and/or discharging the material web; or integrated into the material web forming device; or the dewatering and drying section, or the application apparatus, or the drying device, or the device for processing and/or picking up and/or discharging the material web.
As already mentioned, the machine according to the present invention can also be used for producing the material web. To this end, the material web dispensing device comprises a material web forming device, which is designed to form the material web continuously from raw material supplied, preferably from a fibrous suspension. As a rule, a dewatering and drying section is then arranged along the fiber material web path between the material web forming device and the application apparatus, which is designed to extract water from the moving material web, at least by way of thermal and/or mechanical action, and to dry the material web at least down to a residual moisture content. The material web smoothing device is arranged along the material web path before the application device and is particularly arranged between the dewatering and drying section, and the application device, or integrated into a drying section portion of the dewatering and drying section. In this connection, it is entirely possible for at least one further material web treatment device to be arranged along the material web path between the material web forming device and the dewatering and drying section; or between the dewatering and drying section and the application apparatus. The material web smoothing device according to the present invention can be connected upstream and downstream, as appropriate, or integrated into the material web performing device on the dewatering and drying section. However, the machine can also be a machine which carries out the medium application and the smoothing of the material web in an offline process. For this configuration the material web dispensing device can include a material web unwind for unwinding the material web from a respective material web reel. The above-mentioned material web smoothing device is arranged along the material web path, before the application device, and is generally arranged between the material web unwind and the application apparatus. It is entirely possible for at least one further material web treatment device to be provided, which is arranged along the material web path between the material web unwind and the application apparatus and, in this case, for the material web smoothing device is connected upstream or downstream, as appropriate, or integrated into the material web unwind.
It should further be mentioned that the contactless application by way of an appropriate application device is also advantageous, in particular when application medium is applied to the moving material web at a plurality of application points in the machine. The material web is less stressed by the contactless application of the application medium than by a contacting application, so the risk of web breaks is reduced and, accordingly, the performance or runnability is improved.
Another embodiment of the present invention also relates to the use of a contactless application unit, in particular a curtain application unit or spray application unit, for applying liquid or pasty application medium to a moving material web, preferably of paper or board, and the use of a material web smoothing device for smoothing the moving material web. According to the present invention, the contactless application unit and the material web smoothing device are used in combination. They are used in an online process within a machine for producing and treating the material web, or in an offline process within a machine for treating the material web. In either process they first apply a liquid or pasty application medium to a moving material web, preferably of paper or board, and secondly they smooth the material web or provide it with gloss.
Moreover, the present invention provides a method for treating a material web, preferably of paper or board. According to the present invention, the method includes at least the following steps:
Regarding the implementation of the method, thought is given in particular to the following sequence, if necessary, first drying, then smoothing, then if appropriate drying once more, then application in a contactless manner, then drying and then if appropriate smoothing once more.
Inter alia, the invention proposes coating in a contactless manner in an integrated process and smoothing by way of a suitable smoothing unit, in particular a calender, it being possible for the smoothing to be carried out before or after the coating. Smoothing by way of a calender before coating replaces a conventional smoothing unit, so that a particularly good base for coating is achieved, and also an improvement in the final quality, exemplified by high smoothness or high gloss, that is achieved in the integrated process. As a result of applying the curtain coating application to a very smooth raw material, a very smooth end product is achieved. The smoothing, according to the present invention, before and/or after the coating application is of particular importance since the coating quality depends on the quality of the raw material (body paper).
Relative to the contactless application of application medium, in particular the contactless coating, thought is primarily given to an application of the application medium such that, first, the application is carried out without contact and, second, no metering and preferably no equalization of the application medium applied, by way of a doctor device or the like, is required. The application of the application medium is preferably carried out from the start both with the correct metering and with adequate uniformity over the surface of the material web. This means that the application to the material web is not carried out in excess, which is what is known as a 1-to-1 application.
The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:
Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate one preferred embodiment of the invention, in one form, and such exemplifications are not to be construed as limiting the scope of the invention in any manner.
Referring now to the drawings, and more particularly to
According to the examples of
In each of the embodiments, along the material web path, after the smoothing unit, a contactless coating unit 20a, 20b or 20c is arranged, such as an application apparatus, preferably what is known as a curtain application unit. The curtain application unit applies application medium, in particular a coating medium, to one side of the material web in a contactless manner. In the case of the curtain application unit the application of coating medium is, at least predominantly, on the basis of a movement induced by the force of gravity of the application medium emerging from a slot nozzle or the like in what is known as a curtain or veil. The application takes place either to that side of the material web, which can be identified as the top side, at least over the major part of the entire material web path; or to that side of the material web which can be identified as the underside of the material web, at least over the major part of the entire material web path, but may possibly be oriented upwards in some regions in the area of the application unit.
Application unit or coating unit 20a or 20b is followed by a final drying section 22a or an intermediate drying section 22b, while coating unit 20c is followed by a further coating unit 24c, which applies medium to the other side of the material web and which, just like coating unit 20c, applies coating medium to the material web in a contactless manner. According to the example of
Along the material web path, coating unit 24b or 24c is followed by a final drying section 26b or 26c and, at the end of the material web path, there is in all three examples, a material web reel-up 28a, 28b or 28c, which is used to reel up the material web coated on one or both sides on what are known as spools.
Now, additionally referring to
Material web M emerging from drying device 30a-1 is led over a guide roller arrangement 38a-1, through a smoothing unit 40a-1. Smoothing unit 40a-1 belongs to material web smoothing device 18a, which is represented by smoothing rolls 42a-1 and 44a-1 acting on both sides of material web M. This can be, for example, what is known as a soft nip smoothing unit or a wide nip smoothing unit.
Material web M is led over a further guide roll arrangement 46a-1 through an application apparatus 20a-1, which has a curtain application unit that is represented by a discharge head 52a-1. Discharge head 52a-1 discharges application medium in a metered manner in the form of an application medium veil or application medium curtain, which strikes the top side of material web M on the basis of the movement of the force of gravity and remains on this side of material web M without further metering and equalization, thereby providing the desired application or coating. Discharge head 52a-1 can advantageously be assigned some edge guiding elements, or the like, for the curtain or the veil, as known from the prior art, see for example, German patents DE 100 12 256 A1, DE 197 35 588 A1 and DE 195 13 531 A1.
Material web M that has been coated with the application medium then enters a convection or hot air dryer 60a-1, as an example of a contactless drying device. In drying 60a-1 material web M and the application medium applied thereto is dried to such an extent that subsequently, by way of a further drying device 70a-1 of the type of drying device 30a-1, contact drying of material web M can be carried out without quality penalties. Drying device 70a-1, together with dryer 60a-1, belong to final drying section 23a.
As can be seen from
A further implementation of machine 10a according to
By way of a contactless drying device 60a-2 which, in addition to a contactless drying function on the basis of hot air, additionally fulfills a contactless guiding and deflection function in relation to material web M. The deflection is carried out in a manner similar to that, which is known as an air turn. Material web M is then fed to further drying device 70a-2 of the type of drying device 30a-1 according to
A configuration corresponding to
If an application of application medium to both sides of material web M is desired, then, given appropriate guidance of material web M, the application medium is first applied to both sides of material web M by way of a corresponding contactless application unit before contactless drying and then, finally, contact drying is carried out. It is therefore not absolutely necessary to provide intermediate drying between the application of the application medium to one side of material web M and the application of the application medium to the other side of material web M.
A configuration corresponding to
Inter alia, it is proposed, in a machine for producing and treating a material web, preferably of paper or board, to provide at least one application device having at least one contactless application unit in combination with at least one material web smoothing device, which, firstly, permit the application of a liquid or pasty application medium to at least one side of the moving material web in a contactless manner and, secondly, smoothing of the moving material web, preceding and/or following the application of medium, in an online process or in an offline process.
While this invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102 28 117.3 | Jun 2002 | DE | national |
This is a continuation of PCT application No. PCT/EP2003/050209, entitled “MACHINE FOR TREATING A SHEET OF MATERIAL, PREFERABLY MADE OF PAPER OR CARDBOARD, AND FOR OPTIONALLY PRODUCING SAID SHEET OF MATERIAL PRIOR TO THE TREATMENT THEREOF, COMPRISING A CONTACTLESS APPLICATION DEVICE AND A MATERIAL-SMOOTHING DEVICE”, filed Jun. 2, 2003.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/EP03/50209 | Jun 2003 | US |
| Child | 11020601 | Dec 2004 | US |
