JP2006508268A - Paperboard product and its manufacturing method - Google Patents

Abstract

The coated paperboard product comprises two or more fiber plies, the outer ply consisting of an intermediate ply of bleached chemical pulp and mechanical pulp or waste paper, the production of one or more surface conditioning devices functioning as a pre-calender. A flexible support provided around the fixed support member, and a flexible jacket so that the fixed support member and the paperboard web run between the jacket and the counter roll with use before coating. A load member provided in association with the support member so that the paperboard web loaded by the load member towards the heatable counter roll and calendered between the jacket and the counter roll is calendered Is the PPS-s10 roughness (ISO 8791-4) of 30-80% as the surface property of the upper surface of the paperboard Hunter Gloss (ISO / DIS8254), having a density in the range of 180-1000 kg / m ³ (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 board products, in particular boxboard, and the economics of their production.

  Cardboard 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 containers Will reduce waste.

Packaging paperboard is often coated and has a multi-ply structure. For food use and medicine and tobacco packaging. Coatings and sizing are used to give the desired properties. The range of surface density for typical folding cardboard is 180-350 g / m ² . The required surface density depends on the required packaging stiffness, and a lighter paperboard is sufficient for a small box. The successful preservation 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 surface density paperboard. Typical applications for paperboard include food packaging, tobacco packaging, postcards, bookboard covers, and various food packages.

  Folding paperboard is often smoothed before coating with a Yankee cylinder that allows for good bulk and stiffness, surface properties are also good, dry shrinkage along the edges is small, but the use of Yankee cylinders is a fast machine Are limited by speed constraints, space requirements for the device, and the large size of the Yankee cylinder. 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 comprises two or more fiber plies, in which case the outer ply is bleached chemical pulp and mechanical pulp, chemithermomechanical pulp, recycled paper pulp, recycled cardboard pulp, or loss. It consists of an intermediate ply of paper. The body typically consists of regenerated mixed pulp, typically between the body and the top surface, typically deinked pulp (DIP), white ledger (ledger), chemithermomechanical pulp (CTMP), or There is a protective ply made of mechanical pulp (GW). The intermediate ply may have a core made of, for example, an old cardboard box (OCC), mixed waste paper pulp (MW), old newspaper (ONP), ground wood pulp (SGW, PGW), or waste paper. The back includes, for example, bleached chemical pulp or chemithermomechanical pulp. In any case, the purpose of the multi-ply structure is to give the surface good print quality, and the dark recycled material is good enough for the intermediate ply. Typical surface density range is 200-400 g / ^{m 2.} A typical cardboard structure is shown in FIG.

  Generally, the pre-processing of the cardboard before the coating process is performed by a machine calendar and / or a Yankee cylinder. The function of the machine calendar is to give the web a uniform thickness characteristic. Surface smoothing is performed by a Yankee cylinder.

  According to the present invention, the cardboard is processed with a long nip calender before the coating process in order to improve the quality of the cardboard over the conventional one, and further, the production operability is improved. As with, speed is not limited. 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.

  The long nip calender suitable for the paperboard calendering process of the present invention will be described in detail with reference to the drawings.

  A calendar suitable for the surface treatment of cardboard of the present invention is shown in FIG. 1-2 and includes a fixed support member 14 and a tubular jacket 12 around it. The counter member 22 to be heated is disposed on the other side of the support member of the tubular jacket 12 so that the web passes between the counter member 22 and the tubular jacket. The fixed support member 14 includes load members 18 and 20, and presses the jacket 12 against the heating facing member 22, thereby enabling calendar processing between the jacket and the opposing member. Both ends of the jacket are secured to end walls 24, 26 that are rotatably mounted with respect to the support member, and the rotational movement of the end walls is independent of the movement of the fiber web to prevent overheating of the jacket. Provided by another drive motor. The drive motor is indicated by a wavy line in the figure.

  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.

  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 10 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 a test batch produced by a long nip calender 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.

  A pilot test was performed to compare paperboard made with a regular Yankee cylinder with paperboard made with the same machine, not smoothed with a Yankee cylinder, and calendered under pilot conditions with the above shoe calendar . As a reference, the same paperboard was calendered with a soft calender.

  The attached FIG. 3 shows the ratio of Bendsen roughness to the resulting bulk. Grades processed by shoe calender are labeled as shoes, and those manufactured by soft nip calender are labeled as soft. Temperature refers to the calendering temperature and the symbol is used to refer to the grade of paperboard made with a Yankee cylinder. A clear trend was observed, which indicated that most of the results measured with the shoe calender were located in a high bulk and smooth range, while the Bendsen roughness was about 500 ml / min or less, while the bulk Is greater than 1.40. Paperboard smoothed with a Yankee cylinder is smooth in terms of roughness, but only has an order of 1.29. It should be noted that the issue concerns the test obtained at the pilot condition and the test shows that the result is improved at the production condition.

The measured value relates to the result of pre-calendering before coating. After the coating treatment, the method has a surface density of 150-500 g / m ² , roughness (ISO 8791-4) of 0.8-3.0 μm, Hunter Gloss (ISO / DIS8254) of 30-80%, density (SCAN P7: 75) it is possible to manufacture the board with 500-1000g / ^{m 3.}

  Compared to previous known grades, the resulting paperboard is bulky and smooth, and in addition, the manufacturing method is not as speed-constrained as the Yankee cylinder. The method provides savings in paper manufacturing and improves economy. In particular, increased capacity is possible using the same paperboard machine with online calendaring. A new mill saves space compared to a Yankee cylinder. Providing higher bulk represents a direct savings in the amount of material and energy required for production, as well as lighter packaging board saves energy over its lifetime and is less likely to be ultimately processed Generate garbage.

FIG. 6 is a cross-sectional view of a long nip calendar with a nip extended between the fully closed shoe calendar and the opposing 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. It is a figure which shows a measurement result in the test group of a graph expression. FIG. 2 schematically illustrates a typical paperboard structure.

Claims (17)

A coated paperboard product,
It has two or more fiber plies, the outer ply consists of bleached chemical pulp and intermediate plies of mechanical pulp and / or waste paper or waste paper pulp, and the paperboard has a surface density of 150-500 g / m ² The production of the product involves the use of one or more surface conditioning devices that function as a pre-calender before the coating process,
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 paper jacket (12) is loaded by a load member (18, 20) towards a heatable counter roll (22) and is present between the jacket (12) and the counter roll (22) ( Load members (18, 20) provided in relation to the support member (14), so that 80) is calendered;
The flexible jacket (12) is mounted on the end wall (24, 26) and mounted on the end of the jacket (12) such that the jacket is rotated with the end wall by a drive mechanism. And at least one end wall;
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 0.8-3.0 μm
Hunter Gloss (ISO / DIS8254) is 30-80%,
The product, characterized in that it has a density in the range of 500-1000 kg / m ³ (SCAN-P7: 75).   The material of intermediate ply consists of one or more materials of the group consisting of ground wood pulp (GW), pressurized ground wood pulp (PGW), Chemotherm mechanical pulp (CTMP), waste paper pulp and waste paper. Product.   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. Surface density is in the range of 180-400g / ^{m 2,} Product according to any one of claims 1 to 5. Surface density is in the range of 180-350g / ^{m 2,} Product according to any one of claims 1 to 5.   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 0-500 ml / min.   The product according to any of the preceding claims, wherein the upper surface has a Bendsen roughness (SCAN-P21: 67) in the range of 0-150 ml / min.   The product according to any of the preceding claims, wherein the upper surface has a PPS-s10 roughness (ISO 87911-4) in the range of 1.0-2.5 µm.   11. A product according to any of claims 1 to 10, wherein the top surface has a Hunter Gloss (ISO / DIS8254) in the range of 35-65%. The product has a density in the range of ^{600-850kg / 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 an intermediate ply of mechanical pulp and / or waste paper or waste paper pulp, and the paperboard is 150-500 g / m ² In a method in which the web to be coated has a surface density and is guided to the surface conditioning device before the coating process,
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 paper jacket (12) is loaded by a load member (18, 20) towards a heatable counter roll (22) and is present between the jacket (12) and the counter roll (22) ( Load members (18, 20) provided in relation to the support member (14), so that 80) is calendered;
The flexible jacket (12) is mounted on the end wall (24, 26) and mounted on the end of the jacket (12) such that the jacket is rotated with the end wall by a drive mechanism. And at least one end wall;
The coated product is a surface property of the upper surface of the paperboard.
PPS-s10 roughness (ISO 8791-4) is 0.8-3.0 μm
Hunter Gloss (ISO / DIS8254) is 30-80%,
The product is characterized by having a density in the range of 500-1000 kg / m ³ (SCAN-P7: 75),
A method characterized by that.   17. A method according to any of claims 16 wherein the pre-calendering process involves the use of surface wetting.

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