FI118387B - Process in connection with the manufacture of a surface glued fiber web, in particular a paper or cardboard web - Google Patents

Description

118387

The invention relates to a process according to the preamble of claim 1, and in particular to a process for the manufacture of a surface-bonded fibrous web, in particular a surface of paper or board.

As is known in the prior art, multi-cylinder dryers of a papermaking machine use a two-wire feeder and / or a single wire feeder. In a two-wire delivery, the drying cylinder groups have two two wires which press one of the webs above and one below the heated cylinder surfaces. Between the rows of drying cylinders, generally horizontal rows, there are free and innumerable strokes on the web that are exposed to flutter, which can cause web breaks, especially when the web is still relatively damp and consequently weak. As a result, there has recently been an increasing use of said single-wire thread, with each dryer cylinder group having only one dryer wire in support of which the web passes through the entire group so that the dryer wire presses the web against the heated cylindrical surfaces of the drying cylinders and the web remains on the outside of the curve. Thus, in a single wire delivery, the drying cylinders ·: · *: 20 are outside the wire loop and the swing cylinders or rollers inside it.

*: · *: In the previously known so-called. in normal single-wire export groups, the heated • · ·. * · rolling cylinders are in the top row and the swing cylinders are in the bottom row, which rows are generally horizontal and parallel to each other. When used in the following, ♦ * the terms '' normal (drying) group '' and '' inverted (drying) group '' refer specifically to the single wire export groups of multi-cylinder dryers of the type mentioned above.

· * · • · • · · · · ϊ. * · J When paper is dried with normal single-wire filament groups on its underside, and if such asymmetric drying is extended substantially to the size of the front drying section, the drying occurs first by drying the underside of the paper web. and as the drying progresses, the drying effect also extends to the 2 nanor side of the paper web. Paper dried in this way generally has a tendency to curl mainly due to one-sided drying, i.e. asymmetric drying.

The curling tendency of the paper is already known to be influenced already with the stripping 5, even at the web forming step, by selecting the difference between the speed of the lip jet and the wire, and other running parameters. However, in paper machines which have a single strand thread for most of the drying section length, or otherwise substantially one-sided drying, other arrangements need to be made in practice to control the paper curl tendency in order to achieve a sufficiently symmetrical drying in the z direction.

It is also known that the curvature of the paper can be controlled by a one-sided air dryer, e.g. When drying one side of the paper, the paper dries and curls to the side that dries last, and the curvature can also be adjusted by wetting the other side of the paper with a humidifier and drying it to straighten the paper.

Reference can also be made to the following U.S. Patent Nos. 91900, 103820, 98387, 101487, 99284, ϊ 20 101488, 105935, 106271, 101987, and 106269 for various curve adjustment operations. These applications provide various applications for curvature adjustment. in connection with the manufacture of a fibrous web.

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As is known in the art in the manufacture of surface-bonded fiber webs, the warping caused by the unilateral drying of the front drying section is largely eliminated by the wetting of the web during surface-sizing. In the prior art surface sizing, the base paper curl • · * ·; · 1 has been effectively eliminated when the web is completely moistened with the surface sizing * ·: .1 ·· and any curvature adjustment has been achieved by M »· .. · Curvature adjustment at the end of the post-drying section. However, one of the most important requirements of the surface-bonded fibrous webs is small curvature, because the tendency of curling impairs the end use of the web, e.g. interfering with printing and copying processes.

In conventional surface-bonded fibrous webs, for example, on coated-fine fine paper machines, the curvature adjustment is accomplished by following the post-sizing post-sizing unit, i.e., in the final post-drying step, the web is dried by drying the web. For example, the front drying section has copy paper dried to a moisture content of 2-4%, after which the web is glued by applying 2-4 g / m 2 starch to the paper, generally having a maximum dry matter content of about 10% dry matter. Thus, about 20-40 g / m 2 of water has entered the web.

One important aim in developing the production of surface-bonded fibrous webs is to conduct surface-sizing at a higher dry matter content, i.e. less water would be used for starch application. , to the web, whereby one of the problem areas is the curvature of the fibrous web.

* · ♦ ** * For the purposes of this specification, high-solids surface sizing is intended to be * *. 20 surface sizing with a dry substance content of the surface sizing compound applied to the web »·. . is greater than 12%, preferably in the range of 15-30%, or when less than 20 g / m 2 of water is supplied in surface sizing. In surface dry sizing of high solids, • · *. ···. the dry matter of the tallow mixture is raised to more than 12%, preferably to 15-30% • 0 m 0 m without increasing the amount of starch applied to the dry paper, thus reducing the amount of water introduced into the web and thereby reducing the post-drying capacity »» ·; *** · 30 -70%, thus reducing post-drying, but in this case, however, the reduced amount of water used in the high-dry surface sizing results in • ♦ #, · * ·. ·, Is at least partially retained after surface sizing, which results in an increased • • »*** work requirement for the curvature adjusters of the post-drying section, as the post-drying section • · 118387 4 black is also provided. Thus, for adjusting the curl tendency of post-drying, the chances of being allocated decrease as much of the curl adjustment capacity goes to eliminate the curl from the front drying section of the base paper. Curve adjustment should be taken into account when dimensioning the post-drying, so focusing on compensating for the curvature provided by the front drying section will result in an increased need for drying capacity in the post-drying design.

The object of the invention is to provide a method for solving warping problems in the manufacture of a surface-glued fibrous web, wherein the web has been unilaterally dried on the pre-drying section so as to have a tendency to warp, conventionally being dried at least partially using surface sizing.

In order to achieve the foregoing and further objects, the process according to the invention is essentially characterized by what is stated in the characterizing part of claim 1.

: In accordance with the invention, in the manufacture of a fibrous web which has been dried by the drying section of the front drying section: 20, such that the fibrous web has a tendency to warp and when used with a surface ... ... mixture of more than 12% dry matter. 15% or when • · *; less than 20 g / m 2 of water is applied to the surface sizing, the curl control operations are already performed with the front drying section when drying the base paper, preferably at the end of the front drying section, when the solids content of the web 25 is greater than 80%. According to the invention, the curvature of the front drying section is reduced to the desired value. The curve adjustment can be accomplished at the end of the front ··· drying section by many prior art curvature adjustment techniques: * ·. the web and the web curvature can be adjusted with humidifying • ·: ***: curvature adjusters, fluidized-air dryersZ, dry-blow • ·:: 30 dryZ-dryers, wire-through dryers / bottom dryers • · · tM · .... : The curvature of the paper is adjusted by the difference between the vapor pressure of the top and bottom cylinders. Li-118387 5 After the surface sizing of the high solids, the post-drying portion in its final stage undergoes adjustment of the curl tendency of the fibrous web, which may arise during post-drying, as is known in the art.

The invention achieves significant advantages, one of the most important of which is that when using high dry solids surface sizing for adjusting the end curvature of the stiffener part, the curvature of the finished surface sizing and post-drying paper web is considerably larger when the base paper curl is worried. At the same time, this results in a reduced need for post-drying, which otherwise would have to be reserved for offsetting the curl from the front drying section with the post-drying section.

Thus, the invention has realized to perform curl adjustment operations directly on the base paper at the final stage of the front drying section, after which the curvature tendency is very small even before surface sizing, whereby the post drying section can focus on the actual curl adjustment caused by the paper drying.

The invention is suitable for use in the manufacture of various types of surface-glued fibrous webs such as '*': paper and board webs such as copying paper, liner and the like * * using high-dry surface sizing, i.e., surface sizing, wherein the solids content is greater than 12%, preferably greater than 15%, or wherein less than ***** 20 g / m 2 of water is introduced into the web during surface sizing.

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The invention will now be described with reference to the accompanying drawings.

Figures 1A and 1B schematically illustrate the effect of curvature adjustment as water sizing decreases.

Figure 2 schematically illustrates the effects on the curvature of the operations performed in connection with the surface "* *" gluing of the invention and the prior art.

118387 6

Fig. 3 schematically shows an embodiment of the method according to the invention in connection with a paper machine.

Figure 4 schematically shows another embodiment of the method according to the invention in connection with a paper machine.

Fig. 5 schematically shows a third embodiment of the method according to the invention in connection with a paper machine.

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Fig. 6 schematically shows a fourth embodiment of the method according to the invention in connection with a paper machine.

In prior art surface sizing applications as shown in Fig. 1A, a curved web 10 is surface-sizing with a dry content of less than 12%, usually 8-10% dry solids, and adjusting operations are performed with a stiff-drying step. web 11A.

As shown in Figure IB, when a high dry solids, i.e., a dry solids content of greater than 12%, is carried out, the surface sizing retains: · · the curl tendency of the web 10 having a tendency to curl after finishing. notwithstanding some of the adjustments made in the web 11B. Although these post-drying section adjustments can reduce the curl tendency of the JK, they are not sufficient to remove the curl remaining from the front drying section to the base paper 10, whereby the after-drying section takes a lot of capacity from the front drying section. * ·; · 'To eliminate the tendency to curl, i.e., reduce the lower surface of the web • · · .1 ·; drying relative to the drying of the upper surface in double-wire or fan blades, whereby machine speed must be lowered in order to: even aim for paper as undistorted as in Figure IA.

· «♦ 7 118387

Fig. 2 is a solid line depicting a state of the art. When the pre-drying section 12 is dried, the web predominantly single-sided starts to increase the tendency to spin and is known in the prior art to minimize the value of 5 through V by dipping the surface sizing through wetting, followed by the need for adjusting the curvature 16 during post-drying. When performing after the pre-drying section 12, the high solids surface sizing 14, which is depicted by the dotted line, occurs that the sizing tendency 14 is reduced only to X, leaving the post-drying section 15 with a high curl 16B, especially due to the bottom sizing. This is solved by the invention so that (as indicated by dashed line 17) the pre-drying section 12 already undergoes the necessary curvature adjustment operations on the web prior to surface sizing to such an extent that the web has a tendency to curl before surface sizing to a desired value Z after the high solids surface sizing 14, the after-drying section 15 has a small curvature tendency 16A in the web, thus also requiring less adjustment than in prior art applications. From the graph, it can be seen that by using the • • i.f i curvature adjustment of the front dehumidifier and the surface sizing of the high solids, it is possible to inject! In this way, in Y, a non-warped web, which is more controlled and lower than the value of prior art V, can be utilized. This reduced dry solder gluing requirement can be utilized for eg speed increase and curve adjustment is better afforded when implemented in two steps. ··· • · * ··. * And especially by blowing directly onto the web.

Figures 3-6 illustrate some embodiments in which the process of the invention is applied to a paper machine in which the front drying section is subjected to drying that causes the web to dry. a tendency to curl, with curl adjustment device (s) at the end of the front ··· drying section •: *; 30 to adjust the curvature to the desired value, followed by * ·· · •; · · Post-treatment hall with a high solids surface sizing and post-drying section with the necessary anti-curl adjusting devices to adjust the curvature of the post-drying web. 3-6, the same reference numerals are used for like parts and subassemblies unless otherwise indicated.

5

Figures 3-6 schematically illustrate a paper machine front dryer section 100, a surface sizing unit 200, and a post-dryer section 300. The front dryer section 100 comprises single wire wire drying groups R1, R2, R3, R4, R5, R6, R7, which are the so-called the blades 20 of the drying roller-10 are located in the top row and the turning cylinders or rolls 21 in the bottom row. Each group has a drying fabric F supported and guided by the web running on drying cylinders 20 against the surface of the drying cylinder and pivoting cylinders / rolls 21 on the outer side of the curve. The guide and guide rolls of wire F are denoted by reference numeral 22. Each pocket space between two adjacent drying cylinders 20 and an intermediate pivoting roller / roller 21 has a runner component 23. The surface sizing unit 200 comprises a surface sizing mixture application roller 41, 42. as a surface sizing agent having a dry substance content of more than 12%, preferably in the range of 15-30%, or less than 20 g / m 2 of water to be applied to the web during surface sizing. After the surface sizing device 200, the web is led to a post-drying section 300, where the web is first dried by a contactless drying apparatus 43, for example by fluidized bed or infrared drying. Thereafter, the post-drying section 300 comprises a single-wire export • · ·! Itt! drying group D1.

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In Figures 3 and 4, the front dryer section 100 has seven single-wire threads • 1 φ drying groups R1-R7 and the front dryer section for adjusting the curl tendency to the web has a water jet 25 and / or a jet of water 25 associated with the last pivoting roller.

• · ·:: ·. 30 • Λ · • · · · 118387 9

In Figs. 5 and 6, the front dryer section 100 has six single-wire thread drying groups R1-R6 for further drying the web, and the front dryer section for adjusting the curl tendency on the web after the sixth dryer group R6 is located directly on the blast drying dryer R8; or is through the wire blasting in a drying group R10.

In the embodiment shown in Fig. 5, the blow-drying dryer group R8 is a so-called horizontal blow-drying dryer group in which the web 10 is guided in substantially horizontal export supported by the wire F through the blow-blow hood 27. The passage of the wire F is guided and supported by the guide and guide rolls 22 and the runnability components 28 disposed on the underside of the blow blade 27, which also improve the adherence of the wire F during the blow-drying. At the top of group R8 for transferring the web from the preceding drying group R6 is a runnability component 29. The blow drying group R8 is followed by a short single-wire feed group R9 from which the web is led to a surface sizing device 200.

:. ·. In the embodiment shown in Fig. 6, the blow-drying group R10 is implemented by placing blowing lugs 30 above the last four drying cylinders 20 of the single-wire drying group for drying the web, while adjusting the curvature formed by the front drying section · ; 1: By blowing through the wire F into the web, or so-called wire-by-wire blow-drying.

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Ij: In the embodiment shown in Fig. 3, the after-drying section 300 comprises two single-wire export drying groups D1, D2 and a water jet / jet 25 and / or a water jet 25 for adjusting the curl tendency of the web after the subsequent drying • · ·. \ t 30 rib box 26. From the drying group D2, the web is subjected to further processing.

* · · • · 1 · ♦ ίο 118387

In the embodiment shown in Fig. 4, the after-drying section 300 comprises one single-wire export drying group D1 and a subsequent horizontal over-drying drying group D3 for further drying the web while adjusting the curl tendency to the web during post-drying. This is followed by 5 short single wire threaded groups D4, from which the web is led to further processing.

In the embodiment shown in Fig. 5, the after-drying section 300 comprises a single-wire drainage drying group D1 and a subsequent blow-drying group D5, which is formed with the blow-blow hood 46 positioned in the mouth-10 cylinder 45. In the blow-drying group D5, the web is further dried while controlling the tendency to curl resulting from the post-drying of the web, followed by a short single-wire application group D6, from which the web is subjected to further processing.

In the embodiment shown in Fig. 6, the post-drying section 300 comprises one single-wire drying group D1 followed by a two-wire applying drying group T1, whereby the web is further dried while the post-drying curl tendency is controlled. Dual-wire export group: T1 comprises two rows of heated drying cylinders 50 and drying cylinders ·· «· ·; ··; Rotating cylinders / rollers 51 spaced between the thighs 50. In the top row, the upstream F1 ·: ··· travels through the drying cylinders 50 and the rotating rollers 51 with steering and •: *; guided by guide rolls and bottom row F2, respectively. Between the rows, the web ·· «♦: is exported for free export and for improved runnability and to prevent fluttering of the web, runner components 53 are placed in the pocket spaces.

The invention has been described above only in some advantageous application examples | referring, however, to the details of which the invention is not intended in any way. * * *. narrowly restrict.

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Claims (15)

A method in connection with the preparation of a surface-bonded fiber web, in particular a paper or cardboard web, in which method the fiber web is dried in a front drying portion (100) by drying which results in curvature of the fiber web, in which method the fiber web is adhered to a surface bonding unit. (200) and in which method the surface-bonded fiber web is post-dried in a rear dryer portion (300), characterized in that in order to bring the curvature of the fiber web to the desired value, the curvature of the fiber web is desirably controlled in the method. the final portion of the front drying portion (100) and that the fiber web is adhered to the surface sizing unit (200) by high-dry surface sizing where the dry matter content of the surface sizing mixture is over 12% or where the web is supplied with less than 20 g / m2 of water. 15 2. A method according to claim 1, characterized in that, in order to control the curl propensity which arises in connection with the post-drying in the surface-glued fiber web, the curry in the rear drying portion (200) is controlled. Method according to Claim 1 or 2, characterized in that the fiber web *: **: 20 is glued in the process with a surface gluing mixture whose dry matter content is above ·: **: 15%. • * • * · · φ 4. A method according to any of claims 1-3, characterized in that the curvature of the fiber web is controlled in the front drying portion (100) while the dry matter content of the web is over 80%. ·· • · Φ φ · Φ ΦΦΦ Φ Φ Method according to any of claims 1-4, characterized in that the web in the # method is wetted with a water jet (25) and / or a mudguard (26) in the front drying section. (100) for controlling the curvature of the track. φ Φ Φ Φ φ Φ Φ • • · 118387 Method according to any of claims 1-4, characterized in that the web of the method is dried in the front drying section with one or more floating dryers for controlling the curvature propensity. 5 Process according to any of claims 1-4, characterized in that the web in the method is dried in the front drying portion (100) with one or more blow dryers (R8; R10) for controlling the curl propensity. Method according to any of claims 1-4, characterized in that the web of the method is dried in the front drying portion (100) with one or more dryers (R10) for blowing through a wire (F) for controlling the curl propensity. 9. A method according to any one of claims 1-4, characterized in that the web in the process is dried in the front drying section for controlling the curl inclination with a drying group located at the end of the front drying section, which applies double-wire traction and in which the curvature of the fiber web is controlled. due to a difference in meadow pressure of the upper and lower cylinders of the dryer group. Method according to any of claims 1-9, characterized in that the web in the process is wetted with a water jet (25) and / or a mudguard (26) in the rear *: drying portion (300) for controlling the curvature of the course. • · e · · • · · • ® · · *. Method according to any one of claims 1 to 9, characterized in that the web of the process is dried in the rear drying portion (300) with one or more floating dryers (43) for controlling the curl propensity. . 12. A method according to any of claims 1-9, characterized in that the web of the method is dried in the rear drying portion (300) with one or more blow dryers. '' (D5) for controlling the tendency to curl 1 • · 118387 Method according to any of claims 1-9, characterized in that the web of the method is dried in the rear drying portion (300) with one or more dryers for blowing through a wire (F) for controlling the curl propensity. 5 Method according to any of claims 1-9, characterized in that the web of the method is dried in the rear drying portion (300) for controlling the curvature with a drying grip (T1) located at the end of the rear drying portion, The curvature of the fiber web is regulated by a difference in meadow pressure of the Upper and Lower Cylinders (50) in the dryer group. 10 Method according to any of claims 1-14, characterized in that the method is used in the manufacture of paper and cardboard webs by high-solids surface adhesive, for example copy paper, liner or other similar surface glued fiber web types. 15 • · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · • • ·· * • · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · ·