FI92620B - Coating device for coating a roll in a size press, paper or cardboard - Google Patents

Description

92620 Coating device for coating a roll of glue press, paper or board Bestrykningsanordning for bestrykning av Vals i en limpress, papper eller karton 5

The invention relates to a coating device for coating a roll of glue press, paper or board or a similar movable substrate, which coating device comprises a rotating coating rod extending against the movable substrate extending over the machine width a coating rod on a moving substrate of the coating material introduced into the coating device.

The invention further relates to a coating apparatus for coating a roll of glue press, paper or paperboard or a similar movable substrate, the coating apparatus comprising a coating chamber bounded by a coating substrate supported by a movable substrate and a coating member acting as a coating member. in the coating agent chamber, the coating agent is traced to be supplied under pressure.

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Today, two alternative methods and devices are commonly used to coat paper or board, namely a blade coater or a rod coater. The present invention relates specifically to the latter rod coaters, which have proven to be very good, especially in film-adhesive press technology. The coating rods currently in use are generally made of steel and are provided with a chrome surface to extend the life of the rod. Fully smooth-surfaced rods have not been used in the surface sizing of the paper, but the surface of the rod is either provided with a groove or a steel wire can be wound on the rod, which forms a solution corresponding to the groove on the surface of the rod. The use of a grooved rod for surface gluing of paper 30 is based on the fact that the depth of the groove determines the thickness of the adhesive film on the substrate to be coated. However, the grooved rod is not well suited for making thin adhesive films because it is very difficult to make sufficiently small-scale grooves 2 92620 and, on the other hand, these grooves are easily soiled. A very significant disadvantage of the grooved rods is also that they wear quickly. Pigmentation of high dry matter content is also completely impossible with grooved rods, as the wear of the rods is excessive in this context. The coating rods currently used have been very small in diameter 5, so that the order of magnitude of the diameter is generally about 10 mm. Small diameter rods are used due to the fact that the rod must be able to adapt to the shape of the surface of the adhesive press roll in order to make the profile of the adhesive film suitable and correct. Large diameter rods could not be used because, due to their thickness, they have been too rigid to provide proper profiling. With regard to the prior art, reference is made in particular to U.S. Patent No. 2,970,564, which discloses a solution for applying an adhesive film or a pigment coating film to rolls of an adhesive press which are transferred to paper in a nip of a film adhesive press. The method according to this publication uses smooth or grooved rods for dispensing the adhesive film. In this publication it is possible to use a smooth surface and 15 small diameter rods (diameter about 9 mm) for surface gluing, but it has not proved to be good enough, and a similar solution has never been put into practice as a result. With regard to the state of the art, reference is also made to FI patent No. 30 147.

With regard to the state of the art, reference is also made to the applicant's previous FI patent application No. 20 891737, which discloses a conventional, small-diameter coating rod consisting of a rod on which sleeves forming a tread are rotatably arranged. In said prior art solution, the sleeves are made of a wear-resistant material, e.g. collected, and are provided with grooves in the same way as known coating rods.

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It is an object of the present invention to provide a solution which avoids the disadvantages associated with the prior art and which provides a significant improvement, in particular in the surface sizing of paper. To achieve this object, the invention is mainly characterized in that the coating rod is a large-diameter smooth-surfaced rod without substantial grooves or protrusions, which is arranged against a movable base so that the coating quantity profile is controllably adjustable.

3,92620

The most significant advantage of the invention over the prior art is that the coating device according to the invention has made it possible to drive very thin adhesive films and coating pastes with a high dry matter content even at high speeds by using a large-diameter coating rod. The device according to the invention has had a coating level of 5 and the coating profile have been very good. Other advantages and features of the invention will become apparent from the following detailed description of the invention.

The invention will now be explained in detail with reference to the figures of the accompanying drawing.

10

Figure 1 is a fully schematic, side view of a film adhesive press in which a coating apparatus according to the invention is applied.

Figure 2 is an enlarged and simplified representation of an embodiment of a coating rod for a coating apparatus according to the invention 15.

Fig. 2A shows a schematic sectional view of an embodiment of the coating rod structure of the coating device according to the invention.

Figure 3 is a side schematic view of a size press equipped with deflection compensated rollers.

Figures 4 and 5 are schematic representations of an embodiment of a solution according to the invention for controlling the profile of the amount of coating.

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Figure 6 is a schematic side view of an embodiment of the invention in which the invention is used to coat directly on a paper or board web.

Fig. 7 is a graphical representation of the test results of a coating apparatus according to the invention, in which the amount of coating is shown as a function of the loading pressure of the coating rod.

4,92620

Fig. 1 schematically shows a film glue press, generally indicated by the reference number 1. The film glue press 1 comprises glue press rolls 2 and 3 so that the first roll 2 and the second roll 3 together form a nip N through which the paper or board web W is passed. In the film adhesive press 1, a first adhesive film Fj is applied to the surface of the first roll 5 by the first coating device 10 and a second adhesive film F2 is applied to the surface of the second roll 5 by the second coating device 20. denoted by reference numeral W \ 10 In the film adhesive press 1 according to Fig. 1, rod coaters corresponding to each other according to Fig. 1 are used as coating devices 10 and 20 for applying the adhesive films Fj and F2 to the surfaces 4 and 5 of the adhesive press rolls 2 and 3. The coating devices 10 and 20 are so-called short residence type coating devices in which the coating agent is introduced into a pressurized coating agent chamber 16,26 before the coating rod 11,21, which in addition to said coating rod 11,21 is bounded by a roll surface 4,5, the coating edge edge walls 14,24 shown and any optional front wall 14,24 The coating rod 11,21 is fitted to a cradle 12,22 of a suitable material, e.g. polyurethane, which supports the coating rod 11,21 along its entire length. The coating rod 11,21 is provided with a suitable drive device (not shown) for rotating the coating rod 20 11,21 in directions opposite to the directions of rotation of the rollers 2,3. In Fig. 1, the cradle holders of the coating rods are further indicated by reference numerals 13 and 23 and the front wall holders by reference numerals 15 and 25. A conventional load hose or the like (not shown) is further arranged between the cradle 12,22 of the coating rod 11,21 and the holder 13,23. , 21 can be loaded against the surface of the roll 4,5 to provide the desired loading pressure.

According to the invention, a smooth-surfaced coating rod 11,21 is used in the coating devices 10,20 shown in Fig. 1. In addition to the smooth surface of the coating rod 11,21 according to the invention, the diameter of the coating rod 11,21 is substantially larger than in the prior art. In the coating device according to the invention, the diameter of the coating rod 11,21 is at least 18 mm and very good results have been obtained in test runs 5,92620 with a coating device in which the diameter of the coating rod was 20 mm. However, an even larger dimension is considered to be the most suitable rod diameter, and the rod is most preferably 25-80 mm in diameter.

5 Especially for wide machines, it is necessary to adjust the coating amount profile obtained by the coating device, which is quite impossible when using a large-diameter coating rod according to the invention, if structures . As a result, alternative solutions for adjusting the profile have been developed for the device according to the invention.

Figure 2 shows an alternative solution by means of which the profile of the amount of coating can be adjusted by means of a large-diameter coating rod according to the invention. In Fig. 2, the roll of the size press is indicated by the reference number 6. The roll 6 is provided in a conventional manner with a coating 7, which is e.g. rubber or the like. For the purpose according to the invention, the most suitable hardness of the surface of the roll 6 is about 35 P&J ± 15 P&J, so the choice of the material of the coating 7 is made on this basis in order to obtain the correct hardness. The coating rod according to the invention is indicated in Fig. 2 by reference numeral 31 20 and in the embodiment of Fig. 2 the coating rod 31 comprises a small-diameter body 32 having a diameter of e.g. 12 mm or less. The body 32 of the rod is provided with a suitable top layer 33, by means of which the diameter of the rod 31 is made sufficiently large. The top layer 33 may be formed e.g. by wrapping a strip or the like around the rod body 32.

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On the other hand, the top layer 33 may also consist of sleeves 33a arranged on the rod body 32, which are suitably fixed to each other non-rotatably. Such a solution is shown in Figure 2A, in which the rod body 32 comprises a threaded rod on which the sleeves 33a are arranged. The sleeves 33a are provided with suitable means 30 for preventing their mutual rotation, and they are tightened to each other in the axial direction by means of a tightening nut 37 screwed onto the rod. To provide sufficient tension 6 92620, the rod 32 may be pre-stretched. The fastening head according to Figure 2A is particularly suitable for large diameter rods with a diameter of more than 25 mm. Contrary to what is shown in the figures, the large-diameter smooth rod can also be formed from a tube made of, for example, chromed copper or steel.

5

The rod 31 is rotatably mounted, e.g., in a cradle 34 of polyurethane, which is fixed to the cradle holder 35. Between the cradle holder 35 and the cradle 34 a e.g. The idea of the solution 10 according to Figures 2 and 2A is that by using a small diameter rod body 32, the load hose 36 can be used to profile the rod 31 in a similar way as in the case of small diameter rods according to the prior art.

Figure 3 shows an alternative solution for how the coating rods according to the invention can be used to correct the coating quantity profile on the rolls of an adhesive press. In Fig. 3, the rolls of the adhesive press are generally indicated by reference numerals 61 and 71. The rollers 61 and 71 form a nip N between them, through which the web W is passed. In the nip N, the adhesive films are transferred to the surface of the web W and the coated web is denoted in Fig. 3 by W \. Of the coating devices of rollers 61 and 71, only the coating rods 41 and 51 are shown in Fig. 3, excluding all other parts of the coating devices. In the embodiment of Figure 3, the coating rods 41 and 51 have a large diameter according to the invention, being at least 18 mm in diameter and preferably 20 mm. In the embodiment of Figure 3, the coating rods 41 and 51 are of uniform construction and closed and thus quite rigid. As a result, the rollers 61 and 71 of the adhesive press 25 in Fig. 3 are deflection-compensated rolls so as to comprise a rigid central axis 62,72, on which the roll shell 63,73 is arranged to rotate. Hydraulic loading devices 64,74 are tracked on the shaft 62,72, which rest in the N plane of the nip on the inner surface of the roll shell 63,73. In addition to deflection compensation, the rollers 61 and 71 may be zone adjustable, although this is not essential to the functionality of the invention. Thus, in the embodiment of Fig. 3, the profiling is performed by means of loading devices 64,74 in the roll nip N itself. The solution according to Figure 3 thus provides coating films with a uniform profile on the surface of the rolls 61,71.

Instead of the hydraulic loading devices 64,74 shown in Fig. 3, the compensation of the deflection of the adhesive press rolls 61,71 can be realized so that the rollers 61,71 are provided with devices arranged inside the roll shell 63,73, by means of which the roll shell temperature 63,73 can be adjusted in zones. In such an embodiment, the profile adjustment of the adhesive films is performed by heating or cooling the rolls 61,71 in zones.

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Figures 4 and 5 show another embodiment by means of which the profile of the amount of coating coming to the surface of the roll can be adjusted as desired. Figures 4 and 5 are schematic machine direction views showing a portion of the roll and the coating on the roll surface. Figure 5 also schematically shows a coating rod. In Figs. 4 and 5, the roll is denoted by reference numeral 91, the outer surface of the roll by reference numeral 91a, the coating of the roll by reference numeral 92 and the outer surface of the coating by reference numeral 92a. According to Figures 4 and 5, the outer surface 91a of the roll is formed to be axially curved, i.e. bombarded. The bombing is greatly exaggerated in these figures, as the bombing is generally on the order of 0.3 mm with a machine width of 7 m. As shown in Figure 4, the outer surface 92a of the roll coating 92 is provided with a negative bombardment so that the coating 92 is considerably thicker at the roll center. Figure 5 shows a situation in which a large-diameter coating rod 81 according to the invention is tracked against a roll. The coating rod 81 is a solid material which is substantially rigid, whereby when the coating rod 81 is loaded against the roll, the coating 92 is compressed at the coating rod 81 so that the compression a of the coating 92 in the roll end areas is considerably greater than the compression b in the center of the roll. Because the coating 92 is thinner at the center of the roll than at the ends of the roll, the compression of the coating at the center is less than at the ends of the roll. In the situation according to Figure 5, the line pressure between the coating rod 81 and the coating 92 is thus the same 30 over the entire width of the machine. Thus, this solution provides a uniform coating amount profile. Instead of a cladding coating rod 81, sufficient rigidity 8 92620 can in many cases be achieved with a solution in which the rod is formed of, for example, a tube of chromed copper or steel.

Of course, it is also quite clear that, for example, by combining the solutions of Figures 3,4 and 5, a good result is also achieved. In such a combination, the adhesive press would thus consist of a solution in which the second press roll is a deflection-compensated or zone-adjustable temperature roll and the second roll is a bomb-rolled roll whose coating is provided with negative bombardment.

The solution in Figure 6 shows the coating directly on the paper or board web W. In Fig. 6, the roll is denoted by reference numeral 110. A paper or cardboard web W is passed over the surface 111 of the roll, and the coating device 100 is coated directly on the web W. The coating device 100 is a so-called a short residence type coating device comprising a large diameter coating rod 101 according to the invention rotatably mounted in the cradle 103. The cradle 103 is normally mounted on a holder 104. The coating rod 101 together with the front wall 102 of the coating device 100 limits the pressure The front wall 102 is normally mounted on the holder 105.

In the test runs performed, excellent results have been obtained with the coating device according to the invention. The test runs were performed with a solution in which a smooth coating rod with a diameter of 20 mm was rotatably mounted on a coating rod cradle of conventional construction. The coating device thus constructed was fitted to an adhesive press. The device was subjected to test runs in pigmentation. In some test runs, the coating paste had a dry matter content of 51% and a viscosity of 700 cPs. During the test runs, the amount of coating varied between 3 and 10 g / m2 / half and the driving speed between 800 and 1200 m / min. Achieved coating quantity profile 011 very good. Cavitation was so low that it was hardly noticeable at all. One reason for this was that the diameter of the coating rod was substantially smaller than in actual roll coaters, where large roll diameters cause cavitation as the film cracks after the nip. The result was substantially better than any of the methods previously studied. Figure 7 further graphically shows 9,92620 test results for another pasta grade. Figure 7 shows the amount of paste obtained as a function of the loading pressure of the coating rod at different driving speeds. The experiments according to Figure 7 were also performed with a smooth rod 20 mm in diameter mounted on a conventional cradle. The coating paste used was SPS kaolin paste with a dry-5 content of 50% and a viscosity of 550 mPas. The press roll was provided with a polyurethane coating. Driving speeds of 300-1200 m / min were used in the test runs. The load pressure indicated in the table refers specifically to the load pressure of the coating bar against the roll. As can be clearly seen from Figure 7, the construction according to the invention provided very thin amounts of coating with a high dry matter content of the paste. The invention thus achieves a significant improvement over the prior art. There is a great need for the method according to the invention in the pigmentation and surface sizing of newsprint and in the surface sizing of SC paper.

The invention has been described above by way of example with reference to the figures of the accompanying drawing. However, the invention is not limited to the examples shown in the figures only, but many modifications are possible within the scope of the inventive idea defined in the appended claims.

Claims (12)

1. Coating device for coating a roll in an adhesive press, of paper or paperboard or of a corresponding movable support, which coating device includes a rotating smooth coating rod (11,21,31.81,101) extending over the machine width and inclined towards the movable support (4,5,7,92a, W) which is supported substantially along its entire length against a hollow (12,22,34,103) and which coating rod is arranged to extend and even out coating material introduced into the coating device (10,20,100) before the coating rod (11,21,31,81,101) in the running direction of the movable support (4,5,7,92a, W), characterized in that the coating rod (11,21,31,81,101) is a large, smooth diameter rod and in the absence of any substantial rafters or elevations, the diameter of which is at least 18 mm and arranged against the movable support (4,5,7,92a, W) in such a way that the profile of the coating material can be regulated in a controlled manner. 15 Coating device for coating a roll in an adhesive press, of paper or paperboard or of a corresponding movable support, which coating device (10,20,100) comprises a coating agent chamber (16,26,106) limited by a movable support (4). 5, W) supported rotating smooth coating rod 20 (11,21,101), which acts as a coating means and extending over the machine width, front wall (14,24,102) of the coating agent chamber, edge seals of the coating device and the movable support (4,5, W) into which coating agent. part chambers (16,26,106) coating means are arranged to measure under pressure, characterized in that the coating rod (11,21,101) is a smooth rod of large diameter and in the absence of substantial rafters or elevations, the diameter of which is at least 18 mm and which is arranged against the movable support (4,5, W) in such a way that the profile of the coating material can be controlled in a controlled manner. Coating device according to claim 1 or 2, characterized in that the diameter of the coating rod (11,21,31,81,101) is 25-80 mm. 13 92620 Coating device according to any of the preceding claims, characterized in that the coating rod (31) comprises a body (32) for the small diameter rod, on top of which a wrapping layer (33) is provided which allows for the profiling of the coating rod (31). in the transverse direction of the machine. 5 Coating device according to claim 4, characterized in that the wrapping layer (33) is formed of strip material wound on top of the body (32) of the rod. Coating device according to claim 4, characterized in that the cover layer (33) of the coating rod (31) is formed of smooth sleeves (33a) which are non-rotatably fixed to each other and arranged on top of the body (32) of the rod. Coating device according to claim 6, characterized in that the sleeves (33a) have been loaded on each other by axial drawing. Coating device according to any of claims 1-3, characterized in that the coating rod (11,21,81,101) is rigid and of uniformly compact material. Coating device according to any of claims 1-3, characterized in that the coating rod (11,21,81,101) with a smooth surface is formed of a pipe. Coating device according to claim 9, characterized in that the tubular coating rod (11,21,81,101) is rigid and of chrome plated copper or chrome plated frame. Coating device according to any of the preceding claims, which is arranged on a roll (2,3,6,91) in a glue press, which roll is provided with a coating (7,92), characterized in that the hardness of the coating (7 , 92) is 30 P&J ± 15 P&J.