FI93883B - Sizing press roll and coating device operating in conjunction with this for coating rolls in a sizing press - Google Patents

Description

93883

Glue press roll and associated coating device for coating a glue press roll Limpress rolls and the same sample with a network of the best finishing knitting for the roll of the limestone 5

The invention relates to a roll of an adhesive press and a coating device for coating a roll of an adhesive press, which adhesive press comprises a pair of nip-shaped rolls through which a paper or board web is passed and in which the rollers of the pair are provided with a rubber or similar coating and comprises a large diameter and smooth coating rod rotating over the machine width, extending over the width of the machine, supported substantially the entire length of the cradle, the coating rod being adapted to spread and flatten the surface of the roll 15 in the direction of travel before the coating rod to the coating agent.

The invention further relates to a roll of an adhesive press and a coating apparatus for coating a roll of an adhesive press, which adhesive press comprises a pair of nip 20 rollers through which a paper or board web is passed and in which the rollers of the pair are provided with a rubber or similar coating and bounded by a rotating, large diameter and smooth coating rod extending across the machine width, acting as a coating member on the roll surface, the front wall of the coating chamber, the edge seals of the coating apparatus and the surface of the roll in which the coating material is coated.

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 have a service life of 93883 2 (for flying they are equipped with a chrome surface. Fully smooth-surfaced rods have not been used for surface gluing, but the surface of the rod is either grooved or a steel wire can be wound on the rod. The use of a grooved rod for surface gluing 5 of paper is based on the fact that the depth of the groove determines the thickness of the adhesive film on the substrate to be coated, but the grooved rod is not well suited for making thin adhesive films because it is very difficult to make sufficiently In addition, a significant disadvantage is that they wear out rapidly, and pigmentation of high dry matter content 10 is also completely impossible with grooved rods, as the wear of the rods is The coating rods currently used have been very small in diameter, with a diameter of the order of 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 the nip of a film adhesive press. The method of this publication 20 uses smooth or grooved rods to dispense the adhesive film. In this publication, it is possible to use a smooth-surfaced and> · small-diameter rod (diameter about 9 mm) for surface gluing, but it has not proved to be good enough, and a similar solution has never been implemented as a result. With regard to the state of the art, reference is also made to FI patent No. 30 147.

25

With regard to the state of the art, reference is also made to the applicant's previous FI patent application No. ... 891737, which discloses a conventional-sized, 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.

II

93883 3

It is an object of the present invention to provide a solution which avoids the disadvantages associated with the prior art, which provides a significant improvement, in particular in the surface sizing of paper, and which corrects the profile of the amount of coating on the rolls of the size press. To achieve this object, the invention is mainly characterized in that the coating rod is a rigid, smooth-surfaced rod without substantial grooves or protrusions, which is fitted against the roll surface so that the coating volume profile is controllably adjustable and at least one of the roll press inwardly a zone-adjustable roll so that by adjusting the deflection of said deflection-compensated roll or by zone-adjusting the temperature of said thermally adjustable roll, the linear contact surface between the coating rod and said roll is adjusted straight.

The most significant advantage of the invention over the prior art is that with the coating device according to the invention, using a large-diameter coating rod in a film-adhesive press in which at least one of the rollers is deflection-compensated, very thin adhesive films and high-dry-paste coatings can be coated. The device according to the invention has had a very good level of coating and the profile of the coating. Other advantages and features of the invention will become apparent from the following detailed description of the invention.

20

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

Figure 1 is a fully schematic, side view of a film sizing 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.

Fig. 2A is a schematic sectional view of an embodiment of a coating rod structure of a coating apparatus.

93883 4

Figure 3 is a side diagrammatic view of an embodiment of the invention which achieves a good result in adjusting the profile of the coating.

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

Figure 6 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.

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 gluing press 1, a first adhesive film Ft is applied to the surface of the first roll by the first coating device 10 15 and a second adhesive film F2 is applied to the surface of the second roll 5 by a second coating device 20, respectively. marked W '.

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 F1 and F2 to the surfaces 4 and 5 of the adhesive press rolls 2 and 3. 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 prior to the coating rod 11,21, which in addition to said coating rod 11,21 is bounded by a roll surface 4,5, an edge wall 14 of the coating chamber (not shown) and possible front walls 14,24 The coating rod 11,21 is arranged in a cradle of suitable material, e.g. polyurethane • 12,22, which supports the coating rod 11,21 over its entire length. The coating rod 11,21 is provided with a suitable drive device (not shown) for rotating the coating rod 11,21 in directions opposite to the directions of rotation of the rollers 2,3. In Fig. 30 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 93883 5) is further provided between the cradle 12.22 of the coating rod 11.21 and the holder 13.23. by means of the coating rod 11,21 can be loaded against the surface 4.5 of the roll to obtain the desired loading pressure.

According to the invention, in the coating devices 10,20 shown in Fig. 1, 5 smooth-surfaced coating rods 11,21 are used. 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 the test runs 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.

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. coating the event. As a result, alternative solutions for adjusting the profile have been developed for the device according to the invention.

20

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 adhesive 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 of the invention 25, the most suitable hardness of the surface of the roll 6 is about 35 P&J ± 15 P&J, so that the choice of the material of the coating 7 is made on the basis of the correct hardness for the ash. The coating rod according to the invention is denoted by reference numeral 31 in Fig. 2 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 rod body 32 30 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 can be formed, for example, by wrapping a strip or the like 93883 6 around the rod body 32.

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 for preventing their mutual rotation and are tightened to each other in the axial direction by means of a tightening nut 37 wound on the rod. The rod 32 may be pre-stretched to provide sufficient tension. 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.

The rod 31 is rotatably mounted in a conventional manner, e.g. in a cradle 34 of polyurethane 15, which is fixed to the cradle holder 35. Between the cradle holder 35 and the cradle 34 a loading hose 36 or similar loading member is traced, by means of which the rod 31 can be loaded against the roll 6. The idea of the solution according to Figures 2 and 2A is that by using the small diameter rod body 32, the rod 31 can be profiled by means of a load hose 36 in the same way as in the case of small diameter rods according to the prior art 20.

Figure 3 shows a preferred solution for how the coating rods according to the invention correct the profile of the amount of coating on the rolls of an adhesive press. In Fig. 3, the rolls of an adhesive press are generally indicated by reference numerals 61 and 71. The rollers 61 and 71 25 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 marked in Fig. 3: on the reference sealine 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 30 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 structurally uniform and closed and thus quite rigid. As a result, the rolls 61 and 71 of the size press 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 traced on the shaft 62,72, which S rest on the inner surface of the roll shell 63,73 in the plane of the nip N. In addition to deflection compensation, the rollers 61 and 71 may be zone adjustable, although not essential to the operation 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 zone by zone. In such an embodiment, the profile adjustment of the adhesive films is performed by heating or cooling the rolls 61,71 in zones.

Figures 4 and 5 show another embodiment by means of which the profile of the amount of coating coming to the surface 20 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 indicated 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. As shown in Figures 4 and 5, the outer surface 91a of the roll 25 is axially curved or bombarded. The bombardment is shown in these figures to be greatly exaggerated, since: generally the bombardment is of the order of 0.3 mm with a machine width of 7 m. According to 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 ends. 30 dalla. 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 being substantially rigid 93883 8, 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 significantly 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 S 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 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 can in many cases be achieved with a solution in which the rod is formed of, for example, a chromed copper or steel tube.

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 IS or a zone-controlled temperature-adjustable roll and the second roll is a bomb-rolled roll whose coating is provided with negative bombardment.

In the test runs performed, excellent results have been achieved with the coating device according to the invention. The test runs were performed with a solution in which a smooth coating rod 20 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 * ePs. During the test runs, the amount of coating varied between 3-10 g / m2 / half and the driving speed between 800-1200 m / min. The achieved coating amount profile 25 was 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 6 further graphically shows 30 test results for another pasta grade. Figure 6 shows the amount of paste obtained as a function of the loading pressure of the coating rod at different driving speeds. See also Figure 6

II

The experiments according to 93883 9 were performed with a smooth rod 20 mm in diameter mounted on a conventional cradle. SPS kaolin paste with a dry matter content of 50% and a viscosity of 550 mPas was used as the coating paste. 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 Table 5 refers specifically to the load pressure of the coating rod against the roll. As can be seen quite clearly from Figure 6, 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-10 drip paper 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 15.

Claims (5)

93883 10 A roll of a size press and a coating apparatus for coating a roll of a size press, the size press comprising a pair of rollers 5 (2,3,61,71) forming a nip (N) through which a web or paperboard web (W) is passed and wherein the rollers (2,3,61,71) of the roll pair are provided with a coating of rubber or the like (7.92) and which coating device comprises a rotating, large diameter and smooth coating rod extending over the width of the machine and extending against the surface of the roll (4,5,7,92a) ( 11,21,31,41,51,81) supported substantially along its entire length in the cradle (12,22,34) 10 and the coating rod being adapted to spread and level the surface of the roll (4,5,7,92a) in the direction of travel before the coating rod (11,21,31,41,51,81) to the surface (4,5,7,92a) of the coating agent introduced into the coating device (10,20), characterized in that the coating rod (11,21,31,41,51) , 81) has a rigid smooth surface, no significant grooves or protrusions a rod fitted against the surface of the roll (4,5,7,92a) so that the coating amount profile is controllably adjustable and that at least one of the rollers (61,71) forming the adhesive press nip (N) is deflection compensated or zone-adjustable inside the roll a roll such that by adjusting the deflection of said deflection-compensated roll or by adjusting the temperature of the thermally adjustable roll by zones, the linear contact surface 20 between the coating rod (41,51) and said roll (61,71) is adjusted straight. 2. An adhesive press roll and a coating apparatus for coating an adhesive press roll, the adhesive press comprising a pair of nip rollers (2,3,61,71) forming a nip (N) through which the paper or board web (W) is passed and wherein the rollers of the pair of rollers (2,3,61,71) are provided with a coating of rubber or the like (7.92) and wherein the coating device (10,20) comprises a coating material chamber (16,26) bounded by a supported surface (4,5) on the roll surface a rotating, large-diameter and smooth coating rod (11,21) acting as a coating member extending over the machine width, a front wall (14,24) of the coating chamber, edge seals of the coating device and a roll surface (4,5) to be fed to the coating chamber (16,26) , characterized in that the coating rod (11,21) is a rigid rod II 93883 11 with a smooth surface, without substantial grooves or protrusions, fitted against the surface of the roll (4,5) so that the coating amount profile is controllably adjustable and at least one of the rollers (61,71) forming the adhesive press nip (N) is a deflection-compensated or zone-internally heat-adjustable roll so that the deflection of said deflection-compensated roll or by adjusting the temperature of the thermally adjustable roll in zones, the linear contact surface between the coating rod (41.51) and said roll (61.71) is adjusted to be straight. Coating device according to Claim 1 or 2, characterized in that both rolls (61, 71) of the pair of rolls 10 are deflection-compensated or zone-adjustable rolls. Coating device according to Claim 1 or 2, characterized in that the roll (91) forming the nip (N) with the deflection-compensated roll (61, 71) is a bombarded rigid roll whose coating (92) is negatively formed on its outer surface (92a). Crowned. Coating device according to one of the preceding claims, characterized in that the hardness of the coating (7.92) is 35 P&J ± 15 P&J. 20 '. · 93883 12