JP2006508269A - Paperboard product and its manufacturing method - Google Patents

Abstract

The coated paperboard product has one or more fiber plies, the outer ply consisting of bleached chemical pulp and an intermediate ply of mechanical pulp and / or waste paper, and the paperboard has a basis weight of 150-400 g / m ² The production of the product involves the use of a surface conditioning device that functions as a pre-calender, the surface conditioning device comprising a fixed support member, a paperboard web, and a jacket And a flexible jacket provided around the fixed support member, and the flexible jacket is loaded by the load portion toward the heatable counter roll so that it travels between the jacket and the counter roll. A load member provided in relation to the support member and the flexible jacket is attached to the end wall so that the paperboard web present in the container is calendered And at least one end wall mounted on the end of the jacket such that the jacket is rotated with the end wall by the drive mechanism, the coated product having a surface property of the upper surface of the paperboard PPS-s10 roughness (ISO 8791-4) is 0.5-2.0 μm, Hunter Gloss (ISO / DIS8254) is ˜35-80%, and the product is in the range of 500-1000 kg / m ³ It has a density (SCAN-P7: 75).

Description

Detailed Description of the Invention

  The present invention relates to a coated paperboard product and a method for producing the same.

  The object of the present invention is to improve the quality of paperboard products, in particular paperboard, and the economics of their production.

  Paperboard is required to have a certain surface quality to ensure the desired gloss and print quality, and rigidity and durability to ensure the functionality of the packaging. Since paperboard is mass produced in a paperboard mill, efficient use of raw materials is also important. These demands are somewhat contradictory. The paperboard can be provided with sufficient gloss by calendering the paperboard, often wetted or heated in a certain manner and pressurized in the nip. The surface fibers and coating of the paperboard are preferably pressed smoothly by this pressing without compressing the intermediate ply (layer) of the paperboard. The compression of the intermediate ply reduces the paperboard stiffness and reduces durability. Intermediate ply compression is often referred to as bulk loss. In this case, bulk is understood as the reciprocal of density, and its loss is therefore equal to the densification compression of paper or paperboard.

  Since the paper or paperboard production process is a very high raw material intensive, even small savings in raw materials can provide significant advantages to competitors. In this regard, the 1% savings can be regarded as a significant competitive advantage and the return on investment is reduced. Saving raw materials is also desirable for environmental reasons. Thanks to the reduced weight structure, the multiple effects of the paperboard of the present invention cover the entire life of the product and ultimately save on transportation by reducing the consumption of raw materials resulting in lighter packaging Will reduce waste.

Packaging board is often coated or multi-ply construction. The basic paperboard typically consists of three plies of fiber, with the upper and back plies made from bleached chemical pulp. The filler ply is made of mechanical pulp, typically ground wood pulp (GW), and is often made of pressurized ground wood pulp (PGW), chemithermomechanical pulp (CTMP), or the filler ply is broken paper. It can also be generated using The side of the paperboard is typically coated twice and the back is coated once. Coating and sizing are used to impart the desired properties. Typical basis weights range paperboard is 180-350g / ^{m 2.} The basis weight required depends on the required container stiffness, and a lighter paperboard is sufficient for a small box. The successful maintenance of paperboard bulk in surface conditioning to provide higher paperboard stiffness results in raw material savings and energy savings by allowing the use of lighter basis weight paperboard. Typical uses for paperboard include tobacco packages, medicine packages, postcards, bookboard covers, and various food packages.

  Paperboard is often smoothed before coating with a Yankee cylinder that allows good bulk and stiffness, surface properties are also good, and dry shrinkage along the edges is small, but the use of Yankee cylinders is in high speed machines Limited by speed constraints, space requirements for equipment, and large size of Yankee cylinders. Other typical processing methods involve wet stack calenders, the disadvantages of which include problems related to runnability and control of water application, and in addition, the extra cost dries the paperboard before and after the calendering process. Caused by need.

  Machine calendars are often used with other calendars to refer to a hard calendar with an inelastic roll. The use of a machine calendar as the only surface treatment method is not recommended. Soft calenders, also called soft nip calenders, have a surface on which the calender roll has elasticity, which can have the same order of hardness as the surface hardness of wood, but is still elastic.

  The object of the present invention is to provide a flat printing surface, high gloss and rigidity on a cardboard with a lower amount of material than before, and the method of the present invention avoids bottlenecks, It is to improve running performance. This object is achieved with the packaging board given in claim 1. The coated packaging board of the present invention includes two or more fiber plies, where the outer ply consists of bleached chemical pulp and mechanical pulp, chemithermomechanical pulp or splinter inner ply.

  According to the present invention, the cardboard is processed with a long nip calender before or during the coating process in order to improve the quality of the paperboard than the conventional one, and further, the operability of production is improved. Like the Yankee cylinder, it is not limited by speed. A long nip calendar suitable for producing the paper of the present invention is disclosed, for example, in the earlier patent US6164198 by the applicant.

  A calender suitable for the surface treatment of paperboard of the present invention includes a fixed support member around which a tubular jacket is placed. A heated counter (counter) member is placed on the other side of the tubular jacket support member to allow the web to pass between the counter member and the tubular jacket. The fixed support member includes a load member, and presses the jacket against the heating facing member, thereby enabling calendar processing between the jacket and the opposing member. Both ends of the jacket are secured to end walls that are rotatably mounted relative to the support member, and the rotational movement of the end walls is separate from the movement of the fibrous web to prevent overheating of the jacket. Provided by the drive motor.

  The long nip calendar suitable for the surface treatment of cardboard of the present invention will be described in more detail with reference to the drawings.

  The method of the present invention for adjusting the surface of a cardboard, coated or not, by means of a surface conditioning device is a fiber web through an extended nip established by a roll in the form of a tubular flexible jacket and a counter roll. It is characterized by supplying. The jacket bends over the length of the nip, thereby pressing it into contact with the opposing roll over a long stretch. Paperboard processed in this way is lighter than currently available paperboard, but the stiffness and surface properties are comparable to currently available paperboard.

  This solution allows for significantly higher travel speeds than those achieved with a paperboard machine with a Yankee cylinder. Furthermore, the running performance is good, which contributes to quality improvement and reduces waste.

  The web speed in the calendar can be greater than 600 m / min, preferably greater than 800 m / min, more preferably greater than 1000 m / min, and even as high as about 4000 m / min. Thus, the calendar does not limit the speed of the paperboard machine. The heated roll described above has a temperature of 150-350 ° C, preferably 170 ° C, and most preferably about 200-250 ° C. The linear pressure at the nip is in the range of 100-500 kN / m, preferably less than 400, and most preferably in the range of about 50-300 kN / m. The maximum pressure at the nip is 3-15 MPa, preferably less than 13 MPa, and most preferably about 0.5-8 MPa.

  The calendar suitable for the surface treatment of the paperboard of the present invention will be described in detail with reference to the drawings.

  In FIG. 1, the paperboard 80 travels through an extended and heated nip 1. The nip 1 is established by a fully closed shoe roll 10 that exists under the web 80. Above the web 80 is a counter roll 22 that can be heated. The fully closed shoe roll includes a flexible jacket 12 that is impermeable to water. The jacket is made of, for example, a fiber-reinforced polyurethane. A fixed fixed support member 14 supports at least one load shoe 18. Between the load shoe 18 and the support member, there is an actuator such as a hydraulic cylinder, which urges the concave load shoe 18 to press the flexible jacket 12 against the opposing roll 22. Accordingly, the jacket 12 is loaded so as to leave the neutral no-load position 11 in a direction away from the center of the fully closed shoe roll. The jacket 12 is secured to the end walls 24, 26 at both ends, thus creating a sealed compartment 13 (see FIG. 2). As also shown in FIG. 1, at least one detection device 99 is mounted in conjunction with the web 80 to detect web breaks. The detection device 99 is connected to a control device 98 that controls the operation of calendar processing according to whether or not the web is torn.

  As shown in FIG. 1, the heatable counter roll 22 is accompanied by a disengagement mechanism including a lever 95 having a pivot point 96 that can be rotated by a hydraulic cylinder assembly 94 and serves as a rotation axis. The disengagement mechanism pushes the opposing roll 22 into engagement with the nip 1 and causes it to disengage from the nip 1.

  Pressurized oil is supplied between the load shoe 18 and the jacket 12, whereby hydraulic pressure is developed across the nip and the jacket is pushed into engagement with the opposing roll 22 across the nip 1. At the same time, the oil prevents the jacket from being damaged from lumps and temperature increases.

  In FIG. 2A, the end walls 24, 26 are shown rotatably mounted on the stub shafts 16, 17 of the support member 14 (the end walls are preferably not integral; As shown in Fig. 3, it is divided into a static part and a rotating part.) A cylindrical shaft 32 is rotatably disposed at one end of the stub shaft via a bearing 34. The support column 36 is disposed on the cylindrical shaft via a self-aligning bearing 38 that allows movement of the sphere to allow deformation / bending of the support member 14 when overloaded. One end of the end portion 24 is fixed to the cylindrical shaft. In the illustrated embodiment, the power transmission mechanism 40, which is a cogwheel, is fixed to the cylindrical shaft outside the end wall. The cogwheel is connected to the transmission device 42 and the drive device 44. The drive shaft 48 is supported by a bearing 70 disposed in a bearing housing 52 that is attached to a support member. A snap gear 54 is disposed at each end of the drive shaft. Preferably, these cogwheels have an extended tooth portion to allow axial movement of the meshing cogwheel attached to the end wall. A further cogwheel 56 is secured to the second end wall 26 in the jacket. Both cogwheels inside the jacket mesh with corresponding cogwheels on the drive shaft. The second end wall 26 is rotatably disposed on the second stub shaft 17. The second stub shaft is fixed to the second support column 58.

  The operation is as follows. During normal operation, the driven heated roll 22 reacts with the fibrous web and the flexible jacket 12 due to the desired pressure applied by the load shoe 18, thereby causing friction-based driving of both the fibrous web and the flexible jacket. Is caused. Thus, during normal operation, the force applied to the nip imparts rotation of the fully closed shoe roll.

  Only in special cases, for example when starting the calendar, it would normally be desirable to operate the independent drive of the fully closed shoe roll 10. If the calendar is activated without first accelerating the flexible jacket 12, it will damage the flexible jacket due to overheating. Furthermore, it develops an exponential tension in the fibrous web during the start-up movement, which will degrade the fibrous web. Accordingly, the independent drive of the fully closed shoe roll is used when the surface calendar process is started. At startup, the nip gap is not closed, but the roll 22 has been moved to a position where it does not contact the nip 1. Prior to moving the heated counter roll 22 into the nip, the drive 44 of the fully closed shoe roll 10 is actuated to accelerate the first end wall 24 via the transmission. The rotation of the end wall causes the rotation of the inner first cogwheel 46 and subsequently the rotation of the drive shaft 48. The drive shaft transmits rotation to the second end wall 26 via a second cogwheel 56. Both end walls are thus accelerated and rotated at the same speed until a desired peripheral speed is obtained which is usually equal to the speed of the fibrous web. The nip is closed by actuating the hydraulic piston 94 to rotate the lever 95, thereby moving the opposing roll 22 into the nip, and the load shoe 18 is subsequently attached to the heating roll 22 by its actuator 20. Forced to contact. When the calendar functions in the desired manner, the drive for the fully closed shoe roll can be deactivated and the press roll can be driven in a conventional manner by frictional forces in the nip 1.

  In FIG. 2B, an alternative embodiment of a drive mechanism for a fully closed shoe roll is shown. This embodiment uses friction to transmit the rotational force.

  FIG. 2B also shows a more preferred layout design for the support members and end walls. The end wall is divided into an inner portion 24A; 26A that is non-rotatably connected to the support member 14, a rotating portion 24B; 26B, and a bearing assembly 24C; 26C therebetween. Self-aligning bearings 23 and 25 that allow the support member 14 to bend are disposed at the ends of the support member 14.

  In the figure, a drive device 44 having a shaft 19B is shown. A disk 19 having a rubber layer on its peripheral edge 19A is mounted on the shaft 19B. The other end of the flexible jacket 12 is fixed between an annular ring 15 that functions as a replaceable force transmission device and the periphery of each end wall. The ring 15 is fixed to the end wall. Fitting gears 46 and 56 are fixed inside the rotating portions 24B and 26B of the end walls. The drive devices 44 and 19 can move to a contact state or a non-contact state with the force transmission device 15. When it is desired to accelerate the fully closed shoe roll 10, the driving device is moved so that the rubber layer 19 </ b> A is in a frictional engagement position with the force transmission device 15. The cogwheel 46 and the drive shaft transmit rotation of the end wall 24 to the other end wall 26 by cogwheels 54, 55, 56 that also function as a synchronizer. Thus, both end walls 24, 26 are operated as described above with reference to FIG. 2A. FIG. 2B schematically further illustrates one preferred functional embodiment of the load shoe 18. Generally, the load shoe 18 is not diametrically disposed with respect to the drive shaft, but is disposed at a right angle as in FIG. 2A.

  The test was that in the test batch produced by the long nip shoe calendar as described above, the paperboard was able to have a better bulk ratio and smoothness than the currently available types of paperboard. Therefore, according to the measured values, the object of the present invention is satisfactorily satisfied.

  The shoe calendar can be driven at a very high speed, and the final gloss finish uses a Yankee cylinder by considering the addition of a high temperature such as about 250 ° C. and the long residence time in the calendar area. It will be equivalent to that achieved with a slower solution. In addition to aspects that directly contribute to paperboard quality, the results include saving mill production space, reducing Yankee cylinder production constraints, and providing a more manageable and easier control system.

  From the viewpoint of the production of the paperboard of the present invention, it is preferable that surface wetting is applied before the calendar treatment. However, the paperboard with the invention can also be produced without surface wetting.

  Tests performed show that better surface properties were obtained for paperboard with the same bulk. A test run was performed on a paperboard that was calendered with the long nip calender described above without smoothing with a Yankee cylinder.

  Method measured for the same grade of paperboard

In the test run, reference board and pilot calendering paperboard is coated twice with a blade coating station, the total amount of the coating is about 24 g / m ^2. The product did not receive final calendar processing.

  Thus, without affecting the bulk, the results show less roughness and greater gloss than those achieved with Yankee cylinders. Based on the test, the interpretation of the test results represents an evolutionary step in terms of cardboard quality and production economy. In general, pilot tests provide results that are inferior to those obtained in the final environment, so even based on these preliminary tests, the method can be made better and more economical than before. It can be concluded that simple paperboard can be manufactured easily. Furthermore, the method can be applied at a much faster speed than a Yankee cylinder.

It is sectional drawing of a long nip calender provided with a long nip between a shoe calendar and a counter roll. FIG. 2 is a partially enlarged view of FIG. 1. FIG. 2 is a partial cross-sectional view of the apparatus shown in FIG. 1 showing the drive mechanism along the roll axis. It is a figure which shows operation | movement of a press shoe in the cross section of a longitudinal direction.

Claims (17)

A coated paperboard product,
One or more fiber plies, the outer ply consisting of bleached chemical pulp and mechanical pulp and / or waste paper filler ply, the paperboard has a basis weight of 150-400 g / m ² and has a top surface And the production of the product involves the use of a surface adjustment device that functions as a pre-calender,
The surface conditioner is
A fixed support member (14);
A flexible jacket (12) provided around the stationary support member (14) so that the paperboard web (80) runs between the jacket (12) and the counter roll (22);
A flexible jacket (12) is loaded by a load member (18, 22) towards a heatable counter roll (22) and is present between the jacket (12) and the counter roll (22). Load members (18, 22) provided in relation to the support member (14), so that is calendered;
The jacket (12) is such that the flexible jacket (12) is attached to the end walls (24, 26) and the jacket (12) is rotated with the end walls (24, 26) by a drive mechanism. And at least one end wall mounted at the end of
The manufacture of the product involves the use of one or more surface conditioning devices that function as a pre-calender before the coating process,
The coated product is a surface property of the upper surface of the paperboard.
PPS-s10 roughness (ISO 8791-4) is 0.5-2.0 μm
Hunter Gloss (ISO / DIS8254) is ~ 35-80%,
Product characterized in that it has a density in the range of 500-1000 kg / m ³ (SCAN-P7: 75).   The product of claim 1, wherein the intermediate ply material comprises one or more materials of the group consisting of groundwood pulp (GW), pressurized groundwood pulp (PGW), chemithermomechanical pulp (CTMP) and waste paper.   The product of claim 1 or 2, wherein the top surface is coated one or more times.   The product according to any one of claims 1 to 3, wherein the back surface is not coated.   The product according to any one of claims 1 to 3, wherein the back surface is coated at least once. Basis weight is in the range of 180-350g / ^{m 2,} Product according to any one of claims 1 to 5. Basis weight is in the range of 180-300g / ^{m 2,} Product according to any one of claims 1 to 5.   The product according to any one of claims 1 to 7, wherein the upper surface has a Bendsen roughness (SCAN-P21: 67) in the range of 0-50 ml / min.   The product according to any one of the preceding claims, wherein the upper surface has a Bendsen roughness (SCAN-P21: 67) in the range of 0-20 ml / min.   10. Product according to any one of the preceding claims, wherein the upper surface has a PPS-s10 roughness (ISO 87911-4) in the range of 0.8-1.5 [mu] m.   11. A product according to any preceding claim, wherein the top surface has a Hunter Gloss (ISO / DIS8254) in the range of 40-65%. The product has a density in the range of ^{750-1000kg / m 3 (SCAN-P7} : 75) having a product according to any one of claims 1 to 11.   13. A product as claimed in any preceding claim, wherein the calendering of the product involves the use of a single nip or multiple nip machine and / or a soft calendar.   14. A product according to any of claims 1 to 13, wherein the pre-calendering of the product involves the use of paperboard surface wetting.   14. A product according to any of claims 1 to 13, wherein the pre-calendering of the product does not involve the use of paperboard surface wetting. A method for producing a coated paperboard product, comprising:
The paperboard product has two or more fiber plies, the outer ply consisting of bleached chemical pulp and intermediate plies of mechanical pulp and / or waste paper, and the paperboard has a basis weight of 150-400 g / m ² In a method, wherein the web to be coated is guided for pre-calendering in a surface conditioning device,
The surface conditioner is
A fixed support member (14);
A flexible jacket (12) provided around the stationary support member (14) so that the paperboard web (80) runs between the jacket (12) and the counter roll (22);
A flexible jacket (12) is loaded by a load member (18, 22) towards a heatable counter roll (22) and is present between the jacket (12) and the counter roll (22). Load members (18, 22) provided in relation to the support member (14), so that is calendered;
An end wall of the calendar device, wherein the flexible jacket (12) is attached to the end wall (24, 26), and the jacket (12) is driven by a drive mechanism to the end wall (24, 26). And at least one end wall mounted at the end of the jacket (12) for rotation therewith.   16. A method according to any of claims 15 wherein the pre-calendering process involves the use of surface wetting.

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