EP0699529B1 - Process and device for printing a web - Google Patents

Description

The invention relates to a method for printing on Material web, in particular a paper web, in which one color is applied to the material web, the material web then dried using heat and then cooled. Furthermore concerns the invention an apparatus for printing a web of material with a printing unit, a dryer section and a cooling section.

When printing on a web of material, the printing ink in the vast majority of cases in liquid form applied. At the high throughput speeds used today the color is usually still not dried enough if the paper web is Leaves printing unit. To get straight to printing to be able to connect postprocessing, for example a cutting, folding, folding and Stapling the printed web, the web is replaced by a Dryer section performed using Heat the inks to be dried. When warm but the printing inks have a certain stickiness on when folding printed sheets is disadvantageous because the leaves are then together cling to. For this reason, the web of material becomes cooled to dry.

It has now been found that the cooled web of material no longer sticks, but a number of has other properties that their further processing difficult or later when using lead to unpleasant side effects. For example, disturbing a crackling or creasing of the paper Viewer's comfort. An elimination of these phenomena would therefore be desirable. Are more critical however, changes in the paper web that affect its finishing complicate. So you can look for such Observe the treatment of the paper web many times, that the web becomes brittle, which sometimes happens when folding leads to a fold break. Stapling is also difficult, because the staple has one or more layers of paper penetrates smoothly.

EP-A-0 627 311 (document according to Art. 54 (3) and (4) EPC) shows a web cooling device in which a printed Material web passes through a dryer. After leaving the dryer will be on both sides of the Apply a sheet of liquid. By evaporation the web is cooled by the liquid. The liquid application takes place with the help of liquid application rollers. After the liquid application, there is a further cooling by a cooling roll.

DE-A-32 07 463 describes a method and an apparatus for drying and subsequent cooling of Goods webs, in particular those made after the Offset printing processes are printed. Here will Printing ink or coating material on the web applied and then dried, being in the Drying zone there is an elevated temperature so that the web after leaving the drying zone as well has a higher temperature. The web is then cooled using chill rolls. On the The web side that is cooled down first becomes a Water film applied before this web page that is cooled a second time. The water film can either by spraying the web or the first cooling roller with water or by steaming the first cooling roller with steam, which is then on the chill roll can condense.

CH-A-467 159 shows a method and an apparatus to treat a paper web in which the paper web passes through a heating device after printing, in the ink is dried. Then it goes through the paper web is a group of water-cooled and continuously driven cooling rollers for cooling the warmed web. There is one on the last chill roll Damping unit with several one above the other Rollers are provided that are constantly with a zone of the chill roll surface is engaged on the paper web is not present. She carries one on this chill roll contiguous film of water so that the cooling roller is moistened before it comes into contact with the material web is coming.

The invention is based on the problem of manageability to improve the material web after printing.

This task is initiated in a procedure mentioned type solved in that the material web after cooling and before further processing under simultaneous Apply moisturized heat and then is cooled again.

The humidification leads to the fact that the moisture of the Paper increases and thus the handling properties be improved. The fragility and brittleness decreases. Although this has not been finally clarified , it is assumed that the simultaneous application of On the one hand, heat and moisture have a positive effect on the absorbency of the paper for moisture but also the material web itself at least something is changed on their surface. Both factors are likely to go hand in hand. By the subsequent cooling becomes the relative humidity the paper web further increased, leading to another Improves handling properties. In addition, the cooling prevents which may become sticky again due to the warming printing inks when folding the paper web to stick layers on top of each other leads.

In a preferred embodiment, the material web to humidify with steam, which on the Material web is condensed. In contrast to one Spraying with water or other liquid the application of steam has the advantage that none Droplets are created that become markings, i.e. one Unrest or ripple on the surface. When a condensate layer forms on the paper web rather, an even film is created which Correspondingly evenly without formation of markings moistened.

Preferably the amount of steam supplied is so limits that the steam drip-free on the web condensed. Even if these drops because of the lack of limitation has no negative impact have the material web, so it is prevented that the drops detach from the material web and fall down. With such a loosening, the liquid layer uneven on the surface of the material web, what should be avoided in principle.

Advantageously, the steam is applied to the material web from below introduced. This increases the efficiency. Of the hot steam always has that over the colder air Strive to ascend. With the introduction the steam from below, this effect is advantageous with exploited.

The cooling preferably takes place immediately after steaming. This ensures that only the Surface with a higher temperature, namely the Temperature of about 100 ° C is applied. The advance the heat inside the paper web is in usually through the inks or a previously applied one Dash more difficult. Of course that will advance not completely prevent the heat. It needs just a certain amount of time. If the cooling now after steaming takes place, the heat is on the surface dissipated again before going inside can penetrate the material web and change there the structure leads.

The humidification is advantageously carried out before Roll the web of material with its moistened side at least partially wraps around. In this way it is created between the material web and the roller Gusset in which the moisture of the surface the film formed into the material web is pressed into it. The wrap angle can be here be relatively small. You just have to apply a certain amount of pressure ensure the material web to the roller. If necessary, this can also be done by a pressure roller take place when the wrap angle approaches zero.

The material web is preferably made up of two in succession Sides moistened. The two sides experience this same treatment. By successively moistening can each side under optimal conditions be exposed to moisture.

The task is at the beginning of a device mentioned type in that in the direction of the Material web adjacent to the cooling section, a moistening section with means for increasing the temperature the material web and then a post-cooling section is provided.

The web of material is again in the moistening section moistened, in the post-cooling section, during the Humidification occurred temperature increase of the material web undone again. At the end of the post-cooling section there is a material web available that has improved handling properties, in particular with less risk of fold breakage and a reduced ripple.

The moistening section preferably has at least a steam spray tube directed towards the material web on. The steam spray tube creates a directed one Steam jet, in this case on with a certain Pressure or a certain speed the material web is directed. The beam is capable of moving on to penetrate the air layer adhering to the material web, so that the steam is directly on the by the previous one Cooling section still colder surface the material web can condense. There he forms one Moisture film that is relatively even. The moisture film then leads directly to one Moisten the material web, at least on its top.

The steam spray tube is preferably on the underside the material web directed. This will, as above already run, the natural tendency of the steam exploited to climb up. It results in a improved transport of the steam and thus an improved Efficiency.

There is preferably one below the steam spray tube Collection tray arranged. In the event that despite of all precautions form drops and from the Detach material web, for example when starting the device, is ensured with the drip pan that the Water can be removed immediately without to cause further damage. This increases the risk drastically reduced by corrosion damage.

In this case, the collecting trough preferably has raised Sidewalls on that together with the material web and optionally at least one guide roller Include steaming room. In this vaporization room a vapor atmosphere can now form. In the desirable In extreme cases, the atmosphere in this Steaming room must be free of air. This improves crucially the transition of the steam to the material web, i.e. the formation of the corresponding condensate film. This in turn has the consequence that the humidification with the necessary reliability in the desired Scope is done.

This is preferably in the running direction of the material web guide roller following the steam spray tube on the same Side of the material web arranged on the too the steam spray tube is arranged. As stated above this arrangement enables the formation of a gusset between the guide roller and the material web. In This gusset becomes on the surface of the material web moisture present through external forces in the material web is pushed in. The time to moisturize this drastically shortens the material web. You can also create a web of material in this way dampen that due to the inks or any strokes applied earlier reduced permeability for water.

The moistening section is advantageous with a Provide suction device. This will make excess Aspirated steam so that it is not or only in to a small extent on other parts of the device can. This also increases the risk of corrosion reduced.

Preferably, the moistening section is above the Cooling section arranged. Here is a normal one Printing system still has enough space. This arrangement also enables existing printing systems retrofit.

The post-cooling section is preferably immediate arranged next to the moistening section. By the increase in temperature caused by steam, that first appears on the surface then removed very quickly, so that the heat has virtually no or little opportunity to do so To penetrate inside the material web.

Another preferred embodiment provides that the post-cooling section as part of the cooling section is formed, from which the material web in front led out at its end, through the humidification section passed through and back in. So there is practically no additional post-cooling section required. Rather, this is in the already existing Integrated cooling section. Often it is Performance of the existing cooling section sufficient or even dimensioned too high so that this Power reserves can be used to humidify with subsequent cooling to be able to.

Fig. 1

eine teilweise schematisch dargestellte Vorrichtung zum Bedrucken einer Papierbahn in einer ersten Ausführungsform und

Fig. 2

die Vorrichtung in einer zweiten Ausführungsform.

The invention is described below on the basis of preferred exemplary embodiments. Show here:

Fig. 1

a partially schematically illustrated device for printing on a paper web in a first embodiment and

Fig. 2

the device in a second embodiment.

A device 1 for printing on a paper web 2 has a printing section shown only schematically 3 on, in a known manner or several colors applied to the paper web 2 will. The printing section 3 is followed by one Dryer section 4 in which the paper web 2 using is dried by heat. To the dryer 4 a cooling section 6 follows in the running direction 5, of the cooling rollers 7 shown in a known manner Case six pieces. The paper web 2 is over with the largest possible wrap angle these cooling rollers 7 out. The cooling rolls can, for example be water cooled. They are used in the Dryer section 4 entered in the paper web 2 To remove heat and reduce the temperature. Behind the cooling section 6 is usually a processing section 8 is provided in which cut, folded, stapled or bound the paper web or further processed in another way becomes.

In the present example, however, the paper web is between the cooling section 6 and the processing section 8 still passed through a moistening section 9, which is followed by a post-cooling section 10.

The moistening section has a web guide several guide rollers 11 to 16, the paper web 2 between two guide rollers 12, 13 and 15, 16, respectively is guided essentially horizontally. In these horizontal ones Sections 17, 18 are steam spray pipes 19, 20 arranged so that they spray a jet of steam against each Align underside of paper web 2. Because the paper web 2 have previously been passed through the cooling section 6 is a correspondingly low temperature has, can by the directed steam jet the paper web 2 condensed steam condense there. He forms a moisture film that is relatively even is. Droplet formation occurs in normal operation almost completely avoided. One can do this in particular by achieving the amount of dispensed Steam controls so that only so much steam is released will, like actually on the paper web can condense.

As can be seen from the drawing, these are the Steam spray tubes 19, 20 following guide rollers 13, 16 see above arranged that the paper web 2 these guide rollers 13, 16 at least partially wrap around. It is formed by it a gusset 21, 22 in which the on the surface the moisture layer of the paper web 2 pressed into the paper web 2, so to speak becomes. This improves the absorption of moisture.

There is one below each of the steam spray pipes 19, 20 Collecting pan 23, 24 arranged so that accidentally but falling water in the form of droplets is caught and can be discharged. Such Water drops can accumulate under unfavorable circumstances when starting up or restarting the device 1 form.

The collecting trays 23, 24 have side walls 25, 26, which are so high that they are together with the paper web 2, more precisely their sections 17, 18, and the guide rollers 12, 13 and 15, 16 each have one Include vaporization chamber 27, 28. These vaporization rooms 27, 28 can be completely filled with steam, i.e. be practically free of air, so that the transmission the moisture with the help of steam on the paper web 2 is further improved.

The moistening section is still with a suction device 29 provided by the superfluous steam can be suctioned off, for example with the help of a Fan 30. If necessary, the extracted Steam can also be returned.

The post-cooling section is connected to the moistening section 10 with two further cooling rollers 31, the increase in temperature that occurred in the humidification section the web 2 reverses again.

The paper web 2 then runs in the usual manner in the Processing section 8 to get there as mentioned above to be processed further.

The moistening section 9 is above the cooling section 6 arranged. There is a corresponding place to disposal. The after-cooling section 10 is the humidification section immediately adjacent. In the illustrated The embodiment is also above of the cooling section 6 arranged.

2 are the same parts provided with the same reference numerals. Corresponding parts are provided with deleted reference numerals.

As can be seen, the after-cooling section 10 'is now Part of the cooling section 6 '. Contrary to that 1 is the paper web 2nd in the cooling section 6 'before entering the humidification section 9 no more than six cooling rollers 7, but only passed over four cooling rollers 7. After that the paper web 2 is led out of the cooling section 6 ', passed through the moistening section 9 and fed back into the cooling section 6 ', where it wraps around another two cooling rollers 7. On in this way it becomes a separate assembly for the post-cooling plant 10 saved. However, stand in the cooling section 6 'only fewer cooling rolls 7 are available. This is but in many cases not critical, because the cooling rollers 7 often have sufficient performance reserves.

Claims (17)

1. Method for printing a material web (2), especially a paper web, in which an ink is applied to the material web (2) after which the material web (2) is dried with use of heat and then subsequently cooled, characterised in that after cooling and before further processing the material web (2) is moistened with simultaneous use of heat and subsequently cooled once more.
2. Method according to Claim 1, characterised in that for moistening the material web (2) is acted upon by steam which is condensed on the material web (2).
3. Method according to Claim 2, characterised in that the quantity of steam supplied is limited in such a way that the steam condenses on the material web (2) free of drops.
4. Method according to Claim 2 or 3, characterised in that the steam is introduced on to the material web (2) from below.
5. Method according to one of Claims 2 to 4, characterised in that the cooling ensues immediately after the steaming.
6. Method according to one of Claims 1 to 5, characterised in that the moistening ensues before a roller (13, 16) round which the material web (2) wraps at least in part with its moistened side.
7. Method according to one of Claims 1 to 6, characterised in that the material web (2) is moistened from two sides one after the other.
8. Device for printing a material web (2) having a printing unit, a drier section (4) and a cooling section (6, 6') characterised in that in the direction of travel (5) of the material web (2) following the cooling section (6, 6') a moistening section (9) with means for raising the temperature of the material web (2) and following this a recooling section (10, 10') is provided.
9. Device according to Claim 8, characterised in that the moistening section (9) has at least one steam spray pipe (19, 20) directed at the material web (2).
10. Device according to Claim 9, characterised in that the steam spray pipe (19, 20) is directed at the underside of the material web (2).
11. Device according to Claim 10, characterised in that a collecting tray (23, 24) is arranged below the steam spray pipe (19, 20).
12. Device according to Claim 11, characterised in that the collecting tray (23, 24) has raised side walls (25, 26) which together with the material web (2) and possibly at least one guide roller (12, 13; 15, 16) encloses a steaming space (27, 28).
13. Device according to one of Claims 9 to 12, characterised in that the guide roller (13, 16) following the steam spray pipe (19, 20) in the direction of travel (5) of the material web (2) is arranged on the same side of the material web (2) on which the steam spray pipe (19, 20) is also arranged.
14. Device according to one of Claims 8 to 13, characterised in that the moistening section (9) is provided with a suction device (29).
15. Device according to one of Claims 8 to 14, characterised in that the moistening section (9) is arranged above the cooling section (6, 6').
16. Device according to one of Claims 8 to 15, characterised in that the recooling section (10) is arranged immediately beside the moistening section (9).
17. Device according to one of Claims 8 to 15, characterised in that the recooling section (10') is constructed as part of the cooling section (6') out of which the material web (2) is led before its end, led through the moistening section (9) and led back in again.

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