WO2010097131A1

WO2010097131A1 - Method for producing a multilayer printing cloth

Info

Publication number: WO2010097131A1
Application number: PCT/EP2009/066572
Authority: WO
Inventors: Jürgen Fuchs; Stefan Kisser
Original assignee: Contitech Elastomer-Beschichtungen Gmbh
Priority date: 2009-02-25
Filing date: 2009-12-08
Publication date: 2010-09-02
Also published as: BRPI0923897A2; DE102009010354A1; EP2401161A1; EP2401161B1

Abstract

The invention relates to a method for producing a multilayer printing cloth (2), in particular a method for producing an offset printing cloth comprising at least one reinforcing carrier layer (4) and at least one rubber layer (6), wherein at least one of the rubber layers of the printing cloth is treated as follows: the surface of the rubber layer (6) facing away from the reinforcing carrier layer (4) is first ground using grinding paper (22), the surface of the rubber layer (6) facing away from the reinforcing carrier layer (4) is then ground using a non-woven grinding pad (40) at least in areas.

Description

description

Method for producing a multilayer printing blanket

The invention relates to a method for producing a multilayer printing blanket, in particular to a method for producing an offset blanket, which has at least one reinforcement layer and at least one rubber layer.

For the quality of a blanket, it is of utmost importance that the individual rubber layers of the blanket, which have an influence on the print quality when using the blanket, comply with exact specifications. So it depends on the individual rubber layers of the blanket that a thickness tolerance of a few hundredths of a millimeter is maintained. In addition, at least the surface of the rubber layer directly involved in the printing must have a well-defined surface texture with a certain surface roughness so that the ink can be well transferred. The defined thickness and the defined surface structure of the print quality-relevant rubber layer of the printing blanket is produced during the production of a printing blanket by grinding the surface of the rubber layer facing away from the reinforcing layer layer with a sandpaper. During the grinding process, it may happen that the ground surface of the rubber layer is damaged. For example, the rubber layer may contain a hard foreign body that partially damages the sandpaper. During the further grinding operation, the surface of the rubber layer in the region of damage of the abrasive paper is then sanded less than the remaining surface, so that a survey remains in the area of damage of the abrasive paper. One Blanket that has such an error can not be used and is considered to be scrap.

The invention has for its object to provide a method for producing a blanket, in particular a method for producing an offset blanket, with which the reject can be at least reduced. The invention is also based on the object to provide a device for producing such a blanket.

According to the characterizing features of claim 1, the object is achieved in that at least one of the rubber layers of the blanket is treated as follows: the surface facing away from the reinforcement layer surface of the rubber layer is first ground with a sandpaper, - is the surface facing away from the reinforcement layer surface of the rubber layer then at least partially sanded with abrasive fleece. The object is further achieved by the independent claim 7.

The sanded surface of the rubber layer is sanded in accordance with the spirit of the invention in a second grinding operation with a compressible abrasive in the form of a nonwoven abrasive web (within the scope of the invention, another compressible abrasive may be used instead of a nonwoven abrasive web). Due to the compressibility of the abrasive fleece material is removed from the rubber layer in the region of the blanket in which there is a fault in the form of a survey, due to the increased contact pressure. In the other areas of the blanket, however, no material or only very little material is removed from the rubber layer due to the low contact pressure of the abrasive fleece to the surface. The advantage achieved with the invention is thus to be seen in the fact that errors in the surface of the rubber layer in the form of surveys can be reliably eliminated and the thickness tolerance of the rubber layer due to the low material removal still be respected. As a result of this process, the scrap can be significantly reduced in the production of a printing blanket.

According to one embodiment of the invention according to claim 2 abrasive is introduced into the entire nonwoven structure of the abrasive fleece. A nonwoven according to the

Training is thus designed as a three-dimensional abrasive. It has been found that, with such a nonwoven loop, defects in a rubber layer in the form of elevations can, on the one hand, be removed particularly well and the material removal in the remaining areas of the rubber layer is particularly low.

According to one embodiment of the invention according to claim 3, the nonwoven abrasive is continuously and endlessly guided over the surface to be ground. The advantage of this development is the fact that an endless sanding fleece can be used. Such a nonwoven abrasive article can either be designed as a nonwoven abrasive roll which is mounted on a rotating cylinder. Alternatively, it is possible an endless

Abrasive fleece designed as a nonwoven abrasive tape, which is clamped on the two rotating cylinders of a belt grinder.

According to a development of the invention according to claim 4, individual edges of the abrasive fleece are guided over the surface to be ground during grinding. The advantage of this development is the fact that the abrasive fleece is hardened in the region of the edges relative to the other areas of the abrasive fleece. It has been found that due to this hardening a defect in the form of an elevation in a rubber layer can be eliminated particularly well, while at the same time the material removal in the remaining areas of the rubber layer can be further reduced.

According to a development of the invention according to claim 5, the blanket on a cover layer of rubber, wherein the surface facing away from the reinforcement layer surface of the cover layer is ground with a nonwoven abrasive. In the offset printing process, the rubber cover layer is directly involved in the printing process, ie printing ink is applied directly to it. For other printing methods, the Cover layer of rubber finally covered with a lacquer layer. Nevertheless, it is also important here that the covering layer of rubber has a defined thickness and a defined surface structure. The advantage of this development is the fact that the surface of the blanket is treated with the abrasive fleece, which is involved in the use of the blanket directly on the pressure. This ensures that this surface has no defects.

According to one embodiment of the invention according to claim 6, which faces away from the reinforcement layer surface of the rubber layer is ground only with a nonwoven abrasive if there is a fault on this surface. The advantage of this development is the fact that is removed by the further grinding process with the abrasive fleece surface only from the rubber layer, if it is absolutely necessary. Another advantage of this development is the fact that the life of the abrasive fleece is extended, since it is used only when it is absolutely necessary.

An embodiment and further advantages of the invention will be explained in connection with the following figures. It shows:

1 is a blanket in cross section, Fig. 2 shows a blanket in plan view,

3 shows an apparatus for producing a printing blanket,

4 shows a device for producing a printing blanket,

5 shows a sanding fleece in cross section,

6 shows a device for producing a printing blanket, FIG. 7 shows a detail from FIG. 6.

Fig. 1 shows a schematic representation of a blanket 2 in cross section. The blanket 2 has at least one reinforcement layer 4 and at least one rubber layer 6 in the form of a cover layer which are connected to one another. Alternatively, the blanket 2 may also have a plurality of reinforcing layers 4 and a plurality of rubber layers 6. The rubber layer 6 must have a defined thickness and on the surface 8, the facing away from the reinforcement layer (ie, the surface 8, which faces the pressure side in the later use of the blanket) have a defined surface structure. This is the case in particular when, as in the case of an offset printing blanket, the surface 8 of the rubber layer 6, which faces away from the reinforcing layer 4, participates directly in the printing process in later use of the blanket. For blankets used for other printing methods, the surface 8 of the rubber layer 6 is provided with a lacquer layer. In this case, too, however, it is important that the rubber layer 6 has a defined thickness and a defined surface structure. To produce the defined thickness and the defined surface 8 of the rubber layer 6, the surface 8 facing away from the reinforcement layer 4 is ground with a sandpaper. Due to damage to the abrasive paper, it may happen that the surface 8 is not completely ground, but has errors in the form of elevations 10.

Fig. 2 shows the blanket shown in Fig. 1 in plan view. It can be seen from Fig. 2 that the elevation 10 may extend in the form of a narrow strip over the entire length in the surface 8 of the rubber layer 6. In connection with FIG. 3, it will be explained how such a strip-shaped defect in the form of an elevation 10 can arise.

Fig. 3 shows a device for producing a blanket in a schematic representation. The device has a unwinding drum 12, from which the blanket 2 is unrolled. Furthermore, the device has a reel drum 14, on which the blanket 2 is rolled up. The directions of rotation of the drums 12, 14 are represented by arrows drawn in the drums 12, 14. Between the drums 12, 14 processing stations 16, 18 and 20 are arranged, with which the surface 8 of the rubber layer 6 of the blanket 2 (see Fig.l) is processed. At the processing station 16, the surface 8 of the blanket 2 is sanded with a sandpaper 22. For this purpose, the sandpaper 22 may be formed, as shown in FIG. 3, as an endless sandpaper belt which is mounted on the cylinders 24, 26 of a belt sander. The cylinder 24 rotates in the direction of the arrow 28, so that the sandpaper belt 22 moves in the direction of the arrow 30. Below the cylinder 24, a counter-pressure cylinder 32 is arranged, and the blanket 2 is guided, starting from the unwinding drum 12 between the cylinder 24 and the impression cylinder 32. In the area between the cylinders 24, 32, the sandpaper belt 22 runs counter to the direction of movement of the printing blanket 2, so that a particularly high relative speed between the blanket 2 and the sandpaper band 22 results. The abrasive paper tape 22 extends over the entire width b of the blanket 2 (see Fig. 2), so that the entire surface 8 of the blanket 2 is ground. In this case, if the sandpaper band 22 has damage in a region, then the defect in the form of the strip-shaped elevation 10 may occur during the grinding process, since no or only a reduced removal of material occurs in the region of the damage.

After the surface 8 has been treated with the sandpaper 22, therefore, the surface 8 of the rubber layer 6 (see FIG. 1) is at least partially ground (namely in the region of the defect) by means of a sanding fleece to eliminate the defect. This is done in the processing station 18. The processing station 18 has for this purpose a cylinder 34 and an impression cylinder 36, between which the blanket 2 is guided. Here, the cylinder 34 rotates in the direction of arrow 38. On the cylinder 34, a nonwoven fabric 40 is stretched in the form of a nonwoven abrasive roll. In this case, it is possible for the abrasive fleece 40 to cover the entire width b of the blanket 2 (see FIG. 2), so that at the processing station 18 the entire surface 8 of the blanket is abraded with the abrasive fleece 40. Alternatively, it is possible to grind with the abrasive fleece only a portion of the surface 8 of the blanket 2. In this case, the processing station must always be moved to the area in which there is an error in the form of a survey 10. Between the cylinders 34, 36, the abrasive fleece 40 moves counter to the direction of movement of the blanket 2, so that the surface 8 of the blanket 2 is ground with the aid of the abrasive fleece 40 at a particularly high speed. Due to the pressure exerted on the cylinder 34 with the aid of the impression cylinder 36, the abrasive fleece 40 is compressed. In this case, the compression of the abrasive fleece and thus the contact pressure in the region of the strip-shaped elevation 10 (see FIG. 2) is greater than in the remaining area of the surface 8 of the blanket 2. Because of this higher contact pressure in the elevation 10 is using the abrasive fleece 40 of Mistake eliminated. In the remaining areas of the printing blanket 2, no or only very little material is removed by the grinding due to the low contact pressure due to the grinding.

In a further processing station 20, the entire surface 8 of the blanket 2 is brushed off with a cleaning brush 42 in order to eliminate grinding residues. The processing station 20 has the same structure as the processing station 16, the only difference being that, instead of an abrasive paper 22, a cleaning brush 42 is clamped. The axes of rotation of the drums 12, 14 and all mentioned cylinders of the processing stations 16, 18, 20 are parallel.

FIG. 4 shows an apparatus for producing a printing blanket, which is constructed substantially the same as the apparatus shown in FIG. 3. The only difference is that the processing station 18 is constructed differently in FIG. 4 than in FIG. 3. In FIG. 4, the processing station 18 is basically constructed in the same way as the processing station shown in FIG 16. The only difference is that a grinding fleece band 44 is clamped in the processing station 18 instead of a sandpaper band 22. With the aid of the processing stations 18 shown in FIGS. 3 and 4, the abrasive fleece 40 or the abrasive fleece band 44 is continuously and endlessly guided over the surface 8 of the blanket 2 to be ground.

FIG. 5 shows a cross section of the nonwoven abrasive used in the nonwoven abrasive fabric 40 (see FIG. 3) and in the nonwoven abrasive tape 44 (see FIG. 4). The abrasive fleece includes a reinforcing layer 46 facing the cylinders of the processing station 18 (see FIGS. 3 and 4). On the reinforcement layer 46, a nonwoven layer 48 is attached. In the entire structure of the nonwoven layer 48 of the abrasive fleece, an abrasive 50 is introduced, so that a three-dimensional abrasive fleece is formed.

FIG. 6 shows an apparatus for producing a printing blanket 2 which is constructed substantially the same as the apparatus shown in FIG. The only difference is the fact that in the processing station 18 on its cylinder 34 contains a differently structured abrasive fleece 40. The abrasive fleece 40 consists in the processing station 18 shown in FIG. 6 of individual elongated nonwoven layers 52 which are attached to the cylinder 18 and protrude in the radial direction thereof. The individual elongated nonwoven layers 52 extend over the entire length of the cylinder 34 so that they cover the entire width b of the rubber layer 6 of the blanket 2 during a grinding operation (see FIG. 2). The individual elongated nonwoven layers 52 are regularly distributed at uniform intervals over the entire circumference of the lateral surface of the cylinder 34 and protrude in the radial direction out of the cylinder, so that the rotary brush shown in FIG. 6 is formed. With the aid of the rotary brush in the processing station 18, individual edges of the abrasive fleece 40 are guided over the surface 8 of the blanket 2 to be ground. Specifically, these are the edges of each elongated nonwoven layer 52.

Fig. 7 shows the detail designated in Fig. 6 with VII enlarged. It can be seen from FIG. 7 that the individual elongated nonwoven layers 52 consist exclusively of nonwoven (ie contain no reinforcement layer). Abrasive 50 is incorporated in the entire nonwoven structure of the individual nonwoven layers 52 so that each individual nonwoven layer 52 acts like a three-dimensional nonwoven abrasive web. The arrow 54 indicates the direction of rotation of the cylinder 34 in the apparatus for producing a printing blanket (see FIG. 6). The rotationally leading edges 56 of each nonwoven layer 52 first strike the surface 8 of the blanket 2 during rotation of the cylinder 34 (see FIG. 6) so that these edges are drawn across the surface 8 to be ground. With the devices shown in Figures 3, 4 and 6, at the processing station 18, the surface 8 of the rubber layer 6 (see Figure 1) can always be abraded with a nonwoven abrasive. Alternatively, it is possible to do so only when the rubber layer 6 actually has an error in the form of a protrusion. In this case, that part of the processing station 18 which carries the abrasive fleece is formed so that it can be lifted from the rubber layer and does not come into contact with the surface 8.

LIST OF REFERENCE NUMBERS

(Part of the description)

2 blanket

4 reinforcement layer

6 rubber layer

8 surface

10 survey

12 unwinding drum

14 rewind drum

16, 18, 20 processing station

22 sandpaper

24, 26 cylinders

28, 30 arrow

32 impression cylinders

34 cylinders

36 impression cylinders

38 arrow

40 abrasive fleece

42 cleaning brushes

44 abrasive nonwoven tape

46 reinforcement layer

48 fleece cover layer

50 abrasives

52 nonwoven layer

54 arrow

56 edge

Claims

claims

1. A method for producing a multilayer blanket (2), in particular method for producing an offset blanket (2), the at least one

Reinforcing layer (4) and at least one rubber layer (6), characterized in that in the manufacture of the blanket (2) at least one of the rubber layers (6) of the blanket (2) is treated as follows:

the surface (8) of the rubber layer (6) facing away from the reinforcement layer (4) is first sanded with a sandpaper (22),

- The facing away from the reinforcement layer (4) surface (8) of the rubber layer (6) is then at least partially ground with a non-woven abrasive (40, 44, 52).

2. A process for producing a multi-layer printing blanket (2) according to claim 1, characterized in that in the entire nonwoven structure of the abrasive fleece (40, 44, 52) an abrasive (50) is introduced.

3. A method for producing a multilayer blanket (2) according to any one of claims 1 to 2, characterized in that the abrasive fleece (40, 44, 52) continuously and endlessly over the surface to be ground (8) is guided.

4. A method for producing a multilayer blanket (2) according to any one of claims 1 to 2, characterized in that during the grinding individual edges (56) of a nonwoven abrasive (40, 44, 52) over the surface to be ground (8) are guided ,

5. A method for producing a multilayer blanket (2) according to one of claims 1 to 4, characterized in that the blanket (2) has a cover layer of rubber and that of the reinforcement layer (14) remote surface (8) of the cover layer with a grinding fleece (40, 44, 52) is ground.

6. A method for producing a multilayer blanket (2) according to any one of claims 1 to 5, characterized in that the of the reinforcement layer

(14) facing away surface (8) of the rubber layer (6) only with a nonwoven abrasive (40, 44, 52) is ground when there is a fault on this surface (8).

7. Apparatus for producing a printing blanket (2), in particular for producing an offset blanket, which has at least one reinforcement layer (4) and at least one rubber layer (6), characterized in that the device contains a unwinding drum (12) from which a blanket (2) is unrolled, and a spaced therefrom Aufrolltrommel (14), on which a blanket (2) is rolled up, and that between the unwinding drum (12) and the

Aufrolltrommel (14) at least two processing stations (16, 18) are arranged,

- wherein the first processing station (16) via a rotatable cylinder (24) drives a sandpaper (22), - and the second processing station (18) via a cylinder (34) a

Abrasive web (40, 44, 52) drives, wherein the axes of rotation of the drums (12, 14) and the two cylinders (24, 34) are arranged parallel to each other.

8. An apparatus for producing a printing blanket (2) according to claim 7, characterized in that the second processing station (18) via the cylinder (34) drives a tensioned, endless nonwoven abrasive web (40, 44, 52), the one the cylinder (34 ) facing Kraftsträgerläge (46) and a cylinder facing away from the nonwoven cover layer (48).

9. An apparatus for producing a blanket (2) according to claim 7, characterized in that the second processing station (18) via the cylinder (34) a Abrasive fleece (40, 44, 52) drives, which consists of individual elongated nonwoven layers (52) , which are arranged on the cylinder (34), that a Rotationsschleifbürste arises.

10. Multilayer blanket (2), in particular offset blanket, which has at least one reinforcement layer (4) and at least one rubber layer (6), characterized in that it is produced according to one of claims 1 to 6.