FI89290B - REFERENCE TO A FRAME RELEASE - Google Patents

Description

89290

Method and apparatus for making a multilayer web

The invention relates to a method for producing a multilayer web as set out in the preamble of claim 1 and to an apparatus for carrying out the method as set out in the preamble of claim 5.

The problem with multilayer webbing is the peel strength between the different layers 10. The problem is exacerbated when running a fines-poor web, as the fines promote the bonding of the layers to each other, as well as when using machine constructions in which the webs are joined together as a multilayer product after the dry limits 15 of the individual webs. Various solutions have been developed to improve the peel strength, including starch jets, feed of fines between layers, optimal adjustment of the dry matter content of the different layers before joining the webs, use of reinforcing mass 20 and increasing the degree of grinding of the masses used in the webs.

The effect of starch jets on peeling is significant, but the solution is economically expensive and requires additional equipment. In addition, the solution causes contamination problems. The supply of fines between the layers also requires additional equipment. Again, optimizing the dry matter content of the various layers requires precise dewatering control in the dewatering area located 30 before the web joints. The supply of fines, in turn, requires its own separate headbox with piping circulation, which makes the solution complicated and expensive. By grinding the pulp, it is possible to increase the amount of fines, but on the other hand, the physical properties of the finished 35 sheets deteriorate. In addition, increased grinding consumes more energy.

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Swedish publication 394,700 (Watanabe) further discloses a method and apparatus for forming a multilayer product, in which a second layer is applied to a first layer running on a conveyor felt by means of an open roll 5 and a wire revolving around it. As the wire and conveyor felt pass the combined web layers between them around the open roll in a particular sector, they move to the periphery of the second roll on the opposite side of the roll, and soon after the transfer point 10 the wire separates from the web and the conveyor felt and web continue. The advertisement mentions that the latter roll is a press roll. It is obvious that this describes the structure of the roll more than the purpose. Here, the 15 points on the second roll do not affect the removal of water from the web, and if any compression were to occur at this point, the water would then flow out fairly evenly on both sides of the web to both the open roll and the water-absorbing transport felt.

20

In addition, Finnish publication 71377 discloses a method and apparatus for manufacturing a multilayer web. Here, an intermediate layer is formed between the outer layers of the web by feeding a thicker pulp 25 from a special thick pulp headbox. Thus, improving the peel strength in this conventional method requires the feeding of a thicker pulp with its thickener pulp boxes, which complicates the machine construction.

30

A further method is known from Finnish patent application 800309, in which a multilayer product is manufactured by joining the tracks between two rolls. No attention has been paid here to the quality of the rollers and the water contents of the tracks in order to obtain an optimal result.

3,89290

The object of the invention is to provide a new method and an apparatus for implementing the method, by means of which the peel strength of a multilayer product can be improved without increasing energy consumption or without having to go for expensive accessory solutions. To achieve this, the method according to the invention is mainly characterized by what is set forth in the characterizing part of claim 1. The apparatus according to the invention, in turn, is characterized by what is set forth in the characterizing part of claim 5.

The invention is based on the observation that in the leaching event of the tracks, the fines can be made to move with the water by mechanical compression, in contrast to the use of suction alone. A strong connection can be realized without suction and wire-dragging surfaces with a suitable choice of rollers.

In addition, the solution can be easily implemented in already existing machine constructions by installing an additional roller with a suitable surface structure under a normal open rubber roll, providing a press nip which forces the fines to move between layers at the earliest possible stage, usually below 12% dry matter.

The invention will now be described in more detail with reference to the accompanying drawings, in which Fig. 1 shows a conventional web layer joining point in a paper or board machine, Fig. 2 shows a layer joining point according to the invention, Fig. 2 illustrates the principle of the invention on a larger scale, Fig. 3 shows Fig. 2 shows a point in a second operating position, Fig. 4 shows a point in Fig. 2 in a third position of use, Fig. 5 shows a joining point according to another alternative, Fig. 6 shows a joining point according to a third alternative 15, Fig. 7 shows the wire sections of a paper or board machine comprising the invention Fig. 8 shows another possible construction of a machine comprising the apparatus according to the invention, and Fig. 9 shows the joining points of the machine of Fig. 8 on a larger scale.

Figure 1 shows a conventional apparatus for making a multi-layer cardboard web. Here, the initially filtered first web W1 on the first wire 3 is guided on the second wire 4, as well as the initially filtered web W2, so that the wires 3, 4 are guided against each other by means of a turning roller 2 on the side of the second wire 4, which may have an open surface.

After the joint, the wires pass between the multilayer web to a transfer suction box 5, where the second wire 4 is detached from the top of the first wire 3,. 89290

D

with which the multi-layer web W formed from both webs W1, W2 continues to travel forward. This is the so-called normal cramping.

The wires 3, 4 carrying the webs W1, W2 in this context mean water-permeable continuous conveyors in which the water permeability is based on their structural openness, i. they are made of a material that is not in itself water-absorbent.

10

Figure 2 shows an apparatus according to the invention, in which there is an additional roll 1 against the turntable 2 at the point where the wires 3, 4 run together on the circumference of the turntable 2 with a web therebetween, the rollers 1 15 and 2 forming a press nip N with which the webs W1, W2 join the multilayer web can be improved. By means of the rollers 1 and 2, the desired line pressure can be provided in the press nip N, which is adjustable depending on the products to be driven steplessly.

20

The position of the press nip N caused by the roll 1 on the common run of the wires 3 and 4 on the circumference of the roll may vary. In Fig. 2 the first wire 3 deviates slightly downwards before joining the wire 4 under the guidance of the wire roll 25 6 and joins the wire 4 running on the roll 2 just before the lowest point of the roll 2 where the nip N provided by the auxiliary roll 1 is located. in a vertical plane. After the nip N, the wires 30 again travel a short distance on the circumference of the roll 2 and then point slightly upwards to the suction box 5. Figure 3 shows a situation where said nip N is located after the lowest point of the roll 2 due to the roll 1 being moved slightly to the right of Figure 2. . Correspondingly, Fig. 4 shows a situation in which the nip N provided by the additional roll 1 is located before the lowest point of the roll 2 at the junction of the wires 4 and 3, i.e. the roll 1 has been moved to the left with respect to the position of Fig. 2.

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The auxiliary roller 1 is preferably arranged to be moved both horizontally and vertically to obtain the most suitable position and the optimal line pressure in the nip N. The auxiliary roller 1 is preferably arranged to be moved to a suitable position during driving, i.e. the position of the nip N in the machine direction can be changed if desired.

A suitable dry matter content of the webs in which they are joined is, after their dry limits, generally above 6%, preferably 8-12%. Both webs W1 and W2 are in this range at the optimum dry matter content for the effect of the invention. At lower dry matter contents, the invention is irrelevant, in addition to which there is a risk of curling in the nip, and at higher values it no longer achieves the desired effect due to the reduced water content. In addition, the dry matter contents influence the choice of the alternatives shown in Figures 2-4, so that when the dry matter contents of the joining webs are high, compression can be performed at an early stage, i.e. nip N can be immediately at the junction of wires 3 and 4. while the water content is still in the appropriate range. Correspondingly, when running low-wet, wet webs against each other, the nip N can only be at the point where the wires 3 and 4 separate from the turntable 2, whereby the webs have wound between the wires 3 and 4 on the roll 2 during normal rotation. are at a suitable water content when they enter the nip N and there is no danger of curling. As a general rule, the thicker grades are run, the farther the nip N should be kept 35 from the junction of wires 3 and 4, because thicker grades have a higher total water content at the junction of the webs.

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This solution has brought about a considerable improvement in peel strength compared to traditional gusk. The advantage of the compression husk according to the invention is due to the fact that the mechanical compression 5 causes the fines to move in a transverse direction with respect to the interface of the layers formed by the webs W1, W2. The advantageous effect of the fines on the peel strength is obtained by causing the water in the web layers and with it the fines to move at the interface of the web layers in the direction of the second roll.

The transfer direction is chosen so that the transfer takes place from the layer immediately adjacent to the web interface where the fines content is higher. This is done in the case of a two-layer web from a web finer in terms of total content to a finer web in terms of total fines across the interface.

With the structure 20 of the rollers 1 and 2 facing each other, the desired transfer of fines with water from one web layer to another with the movement of water across the interface of the web layers can always be obtained. This can be achieved with great certainty by arranging the rolls and wire structures 25 so that one of the rollers together with the wire on it collects a larger part, preferably more than 90% of the water compressed at the press nip N from the webs W1 and W2, one of the rolls being open and the other the rolls have a smooth-30 surface roll with a soft surface, about 30-250 PJ, most preferably about 50-200 PJ. The unit PJ is a commonly used unit of hardness for paper machine roll coatings. As such a roll, for example, a normal rubber-coated lump-breaker roll 35, i.e. a "lump-breaker roll", can be used, but naturally any suitably soft roll can be used for this point.

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With the roll hardness values defined above, a kind of "long nip" is created in the nip N, and with this structure, the crushing of the track can be avoided. In addition, it should be noted that in this connection as well, it is possible to speak of line pressure, because the compression pressure at such points is always determined by means of line pressure, which can always be determined by standard methods.

In the construction of Figures 2-4, the turning roll 2 is a roll with an open surface 10 and the additional roll 1 is a smooth surface roll, whereby the nip N causes water movement from both layers formed by the webs W1 and W2 in the direction of the roll 2 to open parts of the roll 2. W1 across the interface to the web W2. In the case of a blind-drilled roll, the water compressed from the web into the bores can be collected by centrifugal force in the collecting trough after the roll 2.

Figure 5 further shows another possibility of enhancing the accumulation of water in the roll 2. Here, the open-surface turning roll is arranged as a suction roll, the suction sector S of which extends at least at the nip N. The suction sector is furthermore located in the roll 2 in the direction of its rotation 25 before the nip N, whereby the dry matter content of the web W2 coming to the joining point and passing at the suction sector S can still be adjusted to suit.

Figure 2a illustrates in more detail the transfer of water and fines according to the invention. The figure shows the nip of Figure 2 on a larger scale in a section perpendicular to the axes of rotation of the rollers 1 and 2. The web 35 W1 on the wire 3 on the roll 1 side is a thicker web, whereby its fines distribution due to the initial filtration through the wire 3 is such that as it goes towards the upper surface forming the incoming interface W12 in the z-direction 999290 the fines content increases and is in the vicinity of the surface. The fines content is illustrated by dots. The thinner web W2, which is introduced by the wire 4 to the junction 5 from the water receiving roll 2 side, has a poorer total fines content than the web W1, although for the above reason it also has the highest fines content near its upper surface, i.e. the incoming interface W12. In the pressing nip N, the fines enrichment of the web W1 is transferred to the web interface W12 on both sides of it, i.e. also to the fines-poor web W2, by means of the water (arrows A) actuated by the press nip. Thanks to the compression, the fiber bonds are also strengthened at the water concentrations prevailing at the compression point.

Thus, when running a multilayer web, such as a 2- or 3-layer web, the web is already compressed at the joint point with a higher compression than in "normal gasification", the compression of which arises only from the tension of the webs. The main principle is to try to transfer the fines by means of controlled compression and at the same time to provide a stronger fiber bond at the earliest possible stage when the dry matter content of the webs is suitable for it. In normal two-layer running (2-level wire), water has so far been sucked out of the dewatering area in only one direction, leaving the fines close to the top surface and the surface against the wire remaining poor fines-30. Even after joining, the wire section has only absorbed water, so that the fines have no longer been allowed to migrate, and the peel strength has remained poor.

35 The compression can be selected according to the product being driven. As a rule of thumb, lower dry matter concentrations are handled at lower line pressures due to more mobile water, and 10,892,290 lower line pressures should also be used due to the risk of curfew. A suitable line pressure is between 0-30 kN / m.

The additional roll 1 is easy to install in connection with already existing multilayer board and multilayer paper machines without making major changes in the equipment constructions, and the invention can be used, for example, for the replacement of old multilayer board and paper machines. As an additional roll 1, for example, a suitably hard rubber-coated roll can be used, in which case it can be fastened under the wire 3 in suitable arrangements so that it can be moved in the machine direction during driving and loaded with the desired force against the roll 2 in all its positions. Alternatively, the load adjustment to achieve the desired line pressure can be done by means of the turning roller 2, whereby the additional roller 1 does not have a load adjustment. The additional roller 1 does not require use, but can be arranged therein if desired.

20

Figure 6 further shows an alternative in which the turning roll 2 on the side of the second wire 4 is a roll which causes the movement of water from the webs in the direction of the additional roll 1. Roll 2 is in this case a smooth roll and 25 roll 1 is an open roll. This option is advantageous in those cases where it is necessary to make water and the accompanying fines move from the finer web W2 introduced by the second wire 4 to the finer poorer web W1 introduced by the first wire 3. 30 This is usually the case when a thinner backing of the two-layer product is run on the lower wire 1 and a thicker body is introduced on the upper wire.

However, the thickness of the web does not always determine from which side 35 the water and fines should be transferred.

In two-layer webs, the layers adjoining the interface W12 are the surface layers of the individual webs W1 and W2, which are formed in essentially the same way U B 9 2 9 ϋ. In this case, the layer containing more fines adjoining the interface W12 is the surface layer of the thicker web. However, in some cases, the surface layer of the thicker web may be poorer than the surface layer of the thinner web driven against it. For example, when running a three-layer web in which the background is run on a lower wire 3, i.e. a thicker web 10 formed of a body layer and a surface layer from the imported body layer and is thus fines-poor, it is advisable to carry out the fines transfer from the direction of the thinner web W1 on the lower wire 3 to the web W2 introduced on the upper wire 4. In this case, the water-receiving roll is on the side of the thicker web W2, i.e. it is a turning roll 2.

20

In addition, it has been found from the test results that when peeling webs of equal basis weight together, the peel strength is also improved by means of the invention. The movement of water and fines 25 across the interface W12 caused according to the invention is also advantageous in improving the peel strength, although it can be assumed that the layers differ in their fines concentrations after treatment. However, a clearer improvement in strength has been obtained by running webs of different basis weights together.

As can be seen from Figures 2-6, in the run, the turntable 2 is driven to the normal run position slightly inside the wire 3, i. below the plane of the wire 3, where a gentle bend in the passage of the wire 3 is created between the wire roll 6 and the suction box 5, in which part the wires 3 and 4 rotate between the webs W1 and W2 to be connected by the roll 2 in a certain sector.

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Figure 7 shows a complete wire section of a multilayer board or paper machine in which the apparatus according to the invention can be used. This is a two-wire machine in which the pulp forming the web W1 is fed to the lower wire 3 from the headbox H1 and the pulp forming the web W2 is fed to the planar portion of the loop formed by the wire 4 above the wire 3 from the headbox H2. The webs are connected as described above at the point where the loop formed by the wire 4 rotates on the lower wire 3 under the guidance of the turning roller 2. In the case of Figure 7, the web W1 forms the body of the finished product and the web W2 its surface. The webs W1, W2 are joined together after the dry boundaries of the webs, i.e. the joint is preceded by a relatively long initial infiltration area on both wires 3 and 4.

Figure 8, in turn, shows another multilayer machine, the so-called kolmiviirakone. The mass forming the web W3 is fed to the planar portion of the loop formed by the second wire 4 from the headbox H3 20, and after the point where the planar portion of the wire 4 turns downwards towards the first wire 3 under the direction of the turning roll 8, the web 9 on the wire 4 a web W4 on a third wire 25 7 rotating around it. The wire 7 runs in the same direction as the lower wire 3 above it, and the pulp is fed to it from the headbox H4. The overlapping webs W3, W4 form, after the junction of the wires 4 and 7, a combined web W2 with both fines-poor surfaces. The web W2 is passed by the wire 4 onto the thinner web W1 coming from the lower wire 3 as described above. The web W3 thus forms the surface of the triple fiber product, the web W4 the body and the web W1 the background.

Figure 9 shows on a larger scale the points where the wires 3, 4 and 7 of the machine of Figure 8 meet. As can be seen from the figure, the structure according to the invention can also be used at point 35 13 89290 where the third wire 7 transfers the web W4 onto the web W3. At the point where the wire 7 rotates around the roll 9, on the side of the second wire 4 there is an additional roll 10, by means of which the effect according to the invention is obtained already at this point between the webs W3 and W4. Since the web W4 has a higher basis weight at this point, it is advisable to arrange the additional roll into a more open roll, whereby the water moves in the direction of the wire 4 and the web W3.

10

In the press nip N formed by the rollers 9 and 10 in Fig. 10, the second wire 4 and the web W2 passing thereto functionally correspond to the first wire 3 and the web W1 in the press nip N of Figs. 1-6, and the third wire 7 15 and the web W4 passing therein correspond to the the second wire 4 and the web W2 passing through it. The invention can therefore be applied at all points in multilayer machines, where the web is transferred on top of one another by means of two wires 20 guided against each other.

The advantages of the invention include the following: 25 - Does not require the addition of additives (starch).

Does not require additional grinding,

Simple and cheap structure.

Also easily suitable for old multi-layer machines.

30 - No additional suction capacity is required, except in the case of using a suction roll 2 instead of an open roll.

Does not limit dewatering settings with initial filtration section.

If the products driven by the machine have a wide weight range of 35 square meters, then the above-mentioned press solution makes it easy to adjust the optimum track interconnection event, either using a press or not, in which case "normal digestion" is performed.

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The following are some of the test runs performed with the apparatus according to the invention.

GUSKAUS PRESS TEST DRIVING ON A TEST MACHINE

1. OBJECTIVE

The problem with multilayer lamination is the peel strength between different layers. The problem is exacerbated when running a finely poor web and with machine constructions where the webs are joined together after the dry limits of the webs.

Various solutions have been developed for the problem: - Starch jets - Feeding of fines between the layers - By optimizing the ka content of the different layers before gushing.

- With the use of reinforcing compound - With grinding in general

Common to these methods are certain limitations and negative factors, such as: price, construction complexity, fouling, energy price, dewatering control limitations, and so on.

New solutions have been considered and preliminary results from one model are presented here.

The main idea is to make the fines move during compression in the track gusting event, without suction and current dragging surfaces.

2. TEST DRIVES

Masses:

Vton sa wrky (Macon Kraft)

The unground grind of the pulp was about 6,600 csf and it was ground about 480 csf.

The same mass was used for both wires.

During the test run, the values of the thick "mass in the range were:

freeness fractions BMN

28 # 200 # through csf%%% at the beginning 484 58.6 33.7 7.7 Avg. 464 58.5 32.3 9.2 at the end 490 59.4 32.4 8.2 is 0 9290

Machine concept - underside Tamflo H (3-row)

- upper wire R

- press section Tampress C + LNP-S

A lump-breaker roll with suitable surface properties was used as an additional roll. Against the couscous roll was a coarse egoutter roll, which was adjusted vertically to achieve the desired compression.

The placement of the dump roller was fixed and was on the same vertical line as the guska roller.

Due to the construction, there is no information on the line loads used.

Fabrics and blankets:

Bottom wire: Scapa & Porritt, 8150 m3 / m2 / h Top wire: Tamfelt Formtec DL HIFI T = 120

Pick-up: Tamfelt Tambat 1210 g / m2 1- area Triaud Gauvain 1650 LNP-S top area: Cofpa 1500

Pilot program (completed)

The program was divided into four parts, each of which had variables: - normal gushing ** - compression gushing (minimum compression) (max., However, so that no curling occurred in the nip)

Driving 1 2 3 4

Speed m / s 5.0 8.3 8.3 3.3

Square weights: - lower wire g / m2 150 100 50 170 - upper wire 50 50 50 50 ** Normal crimping means that the rag roll under the wire was moved further away from the nip, so that the crimping roll could be pressed about 10 mm inside the lower wire.

Since this was a preliminary run, the dry boundaries on the wires were tried to keep the ratio. constant in place, being approx. 8.0-8.5 m on the lower wire and approx. 6.0-5.5 m on the upper wire from the headbox.

The gloss densities were measured with an NDC meter. The effect of guskaization on the ka content after the wire suction roll was also monitored.

Press loads were kept constant: 1- nip 80 kN / m 2- - "- 120 3- 500 (shoe) ie 89290

3. REVIEW OF RESULTS

Determination of laboratory results:

Fragmentation- Bond was the most important parameter. Since the bond usually has a large scatter, the determinations were made on four sheets of two strips = the average of 40 measurement results.

Other determinations are normal averages of five measurements.

The laboratory results are shown in Tables 1-4.

3ond.

In all part times, the compression crushing had an improving effect on the crushing compared to normal crushing: 3.3 m / s, approx. 170 + 50 g / m2 127 - * - 176 J / m2 ® +38.6% 5.0 ”approx. 150 + 50" 146 174 "- +19.2 "8.3" n. 50 + 50 "91 * 99" - + 8.8 "8.3" n.100 + 50 "94 ^ 115" - +22.3 "

When the basis weight of the body was more than 150 g / m2, the minimum compression resulted in an optimal compaction, while less than 150 g / m2 max. compression was optimal.

On the other hand, it should be noted that although a significant improvement in the bond level was achieved during the compression gust period, the corresponding 2-layer sheet bonds were still only 45-57% compared to the 1-layer sheet bond.

Other physical properties of the sheet.

Optimal for Bond when driving under compression, no clear systematic line was visible under the effect of compression, as can be clearly seen from the appendices.

The dry matter contents.

Calculated according to NDC measurements, the pre-gasification concentrations in the relatively Constants: (8.3 - 10.0%) averaged 9.0%. -up - "- (11.0 - 12.0%) -" - -11.3%

Measurements with NDC before the wire suction roll and the ka.p concentration of the samples after the suction roll showed that the ka.p content increased by compression gasification by about 0.5 to 1.0% units compared to normal digestion.

4. COMMENTS

- There were no technical problems with the drive - The roller roller was running wet and no dirt was visible.

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Although the compression was not precisely determined, it can be stated that for heavy grades above 200 g / rr, 2 the compression load was very small.

However, it was higher than normal with gas. With light basis weights of less than 200 g / m2, much more could be compressed.

- What factor then contributes to the fact that the columning improved even with the slightest pressure?

At least the difference with normal gushing is that in compression (even in a small amount) some of the free water and fines are forced in the direction of the open roll. The tumbler roller is closed.

- Even when driving with a small amount of pressure, it was clear that water was leaving the open roller.

- The test roller was without use during the test run. No problems.

Table 1.

GUSKAUSPURISTINKOEAJO

LABORATORY RESULTS

is S92S0

Normal Purist. Squeeze, gushing light max.

Tissue point n = 1819 1817 1818

Speed m / s

Headbox consistency: - lower wire% 0.63 0.63 0.63 - upper wire% 0.15 0.15 0.15

Next case: - bottom wire% n. 9.0 n.10.0 n.10.0 - top wire% "12.0" 11.o "11.0

Ka.pit.imut. After food. % 19.0 20.7 21.2

Weight per square meter: - total g / m2 207 202 201 - lower wire "152 152 152 - upper wire" 55 50 49

Density kg / m3 535 546 518

Porosity (G-H) s 19.5 20.6 18.3

Traction index: - machine. Nm / g 48.5 44.4 42.7 - cross section. "26.8 27.0 25.2 - ko / po 1.81 1.64 1.69 - geom.ka." 36.1 34.6 32.8

Elongation: machine. 2.9 "deviation

Scott Bond J / m2 146,174,170

Rest index kPa * m2 / g 3.18 2.74 2.66 RCT machine. kN / m 2.38 2.33 2.22 "deviation." 2.08 2.01 2.02 f 19 09290

Table 2.

GUSKAUSPURISTINKOEAJO

LABORATORY RESULTS

Normal Purist. Squeeze, gushing light max.

Tissue point n = 1821 1822 1823

Speed m / s 8.3 8.3 8.3

Headbox · consistency: - lower wire% 0.46 0.46 0.45 - upper wire% 0.22 0.22 0.22

Next case: - lower wire% n.9.1 n.8.3 n.8.3 - upper wire% "11.0" 11.0 "11.0

Ka.pit.imut. After food. % 19.7 19.4 20.0

Weight per square meter: - total g / m2 150 150 149 - lower wire "101 101 101 - upper wire" 49 49 48

Density kg / m3 530 520 527

Porosity (G-H) s 14.6 13.0 14.2

Traction index: - machine. Nm / g 50.9 56.0 48.8 - cross section. "26.5 24.6 25.0 - ko / po 1.92 2.28 1.95 - geom.ka." 36.7 37.1 34.9

Elongation: machine. % 3.8 2.6 2.9 deviation. % 4.4 3.8 3.1

Scott Bond J / m2 93 91 115

Rest index kPa * m2 / g 3.16 3.04 3.13 RCT machine. kN / m 1.51 1.57 1.56 11 cross section. '1.26 1.21 1.25

Table 3.

GUSKAUSPURISTINKOEAJO

LABORATORY RESULTS

20 B 9 2 9 ϋ

Normal Purist. Squeeze, gushing light max.

Tissue point n = * 1827 1825 1826

Speed m / s 8.3 8.3 3.3

Headbox consistency: - lower wire% 0.32 0.32 0.32 - upper wire% 0.22 0.22 0.22

Next case: - lower wire% n.8.3 n.8.3 n.8.3 - upper wire% "11.0" 11.0 "11.0

Ka.pit.imut. After food. % 18.6 18.5 19.3

Weight per square meter: - total g / m2 104 98 100 - lower wire "53 53 53 - upper wire" 51 45 47

Density kg / m3 487 484 482

Porosity (G-H) s 8.1 6.5 8.8

Traction index: - machine. Nm / g 48.2 51.4 53.0 - deviation. "25.8 24.9 26.3 - ko / po 1.87 2.1 2.0 - geom.ka." 35.3 35.7 37.3

Elongation: machine. Deviation of

Scott Bond J / m2 91 81 100

Holiday index kPa * m2 / g 3.02 3.03 3.15 RCT machine. kN / m 0.82 0.71 0.69 "deviation." 0.66 0.60 0.63 21 09290

Table 4.

GUSKAUSPURISTINKOEAJO

LABORATORY RESULTS

Normal Purist. Squeeze, gushing light max.

Tissue point n = 1829 1830 1831

Speed m / s

Headbox consistency: - lower wire% 0.65 0.65 0.65 - upper wire% 0.25 0.25 0.25

Next case: - lower wire% n.9.4 n.9.4 n.9.4 - upper wire% "12.0" 12.0 "12.0

Ka.pit.imut. After food. % 20.9 21.3 22.0

Nelicmas: - total g / m2 218 221 247 - lower wire '179 179 179 - upper wire' 39 42 68

Density kg / m3 519. 508 549

Porosity (G-H) s 16.1 16.9 18.7

Traction index: - machine. Nm / g 49.2 50.0 49.4 - deviation. "26.4 25.4 24.6 - ko / po 1.86 1.97 2.01 - geom.ka." 36.0 35.6 34.9

Elongation: machine. Deviation of

Scott Bond J / m2 x27 176 172

Rest index kPa * m2 / g 2.99 2.98 2.67 RCT machine. kN / m 2.63 2.64 3.2 "deviation." 2.15 2.14 2.5

Claims (14)

A method of producing a multilayer web by means of a paper or cardboard machine in which a prefiltered web (W1) is formed on a first wire (3), and a second web (W2) formed on top of second wire (4) is brought on top of said web in such a way that the wires (3, 4) are brought against each other by a turning roller (2) at which the second wire (4) moves around the roller (2) and is placed on top of the first wire (3) in such manner. means that the webs (W1, W2) form the joined layers of a multilayer web after said point, wherein against the turn roll (2) on the side of the first wire (3) there is an additional roll (1), the rollers (1, 2) ) are so mounted that a press nip (N) is formed therebetween, the rollers are loaded against each other, the desired force being used to effect a suitable line pressure having an effect on the bond between the webs (W1, W2), characterized in that with said line pressure caused by the nip (N) movement (A ) of the water in the web layers and the movement of the fines thereby at the interface (W12) of the web layers towards one of the rollers in such a way that the direction of movement of the water and the fines is affected by allowing one of the rollers (1, 2) together with the wire therein to collect most of it; preferably over 90% of the water pressed out of the webs (W1, W2) at the press nip (N) in such a way that a roll with an open surface is used as one of the rolls (1, 2) and a roll with a smooth surface and with a surface hardness between 30-250 PJ is used as the second of the rollers. 2. A method according to claim 1, wherein webs: which have the major deviating fines content of their surface layers bound by the interface (W12) are joined together, characterized in that the movement (A) of the water and fines at the interface (W12) are caused to take place. from the surface layer, which has a higher content content11. 3 99 90 27 ~ Method according to claim 1 or 2, characterized in that the suction function which operates at least at the nip (N) Mr is arranged in the roller which. collects most of the water. 5 Method according to any of the preceding claims 1-3, characterized in that the position of the nip (N) in the machine direction changes during the run. Apparatus for producing a multilayer web in a paper or cardboard machine comprising a first wire (3) arranged for conveying a first web (W1) and a second wire (4) arranged to transport a second web ( W2), said li '. means comprising a reversing roll (2) in which the second wire (4) is arranged to move around the roll (2) to be placed on top of the first wire (3) to bring the webs (W1, W2) together to form the joined layers of a multi-layer web, wherein additional roll (1) is located on the side of the first wire (3) against the turn roll (2), the rolls (1, 2) being mounted such that a press nip (N) is formed. In between, the device further comprises means for loading the rollers (1, 2) with a desired force against each other to provide an appropriate line pressure affecting the bond between the webs (W1, W2), characterized in that the rollers (1, 2) and the wires (3, 4) have such designs that the nip causes the movement (A) of the water in the web layers and the movement of ·· -30 fines at the interface (W12) of the web layers towards one of the rollers in such a way that one of the rollers together with the wire on it collects most things, for example approximately 90%, of the water being squeezed out by: the webs at the press nip (N), one of the rollers (1,?) having an open surface and the other of the rollers having one. . surface with a surface hardness of between 30-250 PJ. 28 89290 Apparatus according to claim 5 in a paper or cardboard machine which combines webs which are substantially different in the fines content of surface layers bonded through the interface (W12), characterized in that the rollers (1, 2) and the wires have such structures that the nip causes the movement (A) of the water and fines at the interface (W12) from the web having a higher fines content in its surface layer. io 7. Device according to claim 5, characterized in that the roller which collects most of the water is the reversing roller (2). Apparatus according to claims 6 and 7 for producing a cross-layer web, characterized in that the first wire (3) consists of the wire which causes the web (W1) to serve as a thicker body layer, and the second wire (4) forms the wire that brings web (W2) which serves as a thinner surface. 20 Device according to claims 6 or 7 for the production of a three-layer web, characterized in that the second wire (4) is the wire which produces a thicker web (W2) consisting of two web layers, the 75 layer (W4) and the surface (W3). wherein a third wire (7) for bringing the backing layer (W4) on top of the surface (W3) lying on the second wire (4) for joining them to form a web (W2) is arranged in connection with said second wire for the first wire (3), and .30 said first wire (3) serves as the wire which produces a web (W1) serving as a thinner backside. 10. Device according to claim 5, characterized; hence, the roller that collects most of the water is an additional roller (1) disposed against the reversing roller (2). 29 09290 11. Apparatus according to claims 6 and 10 for the production of a cross-layer web, characterized in that the first wire (3) is the wire which produces a web (W1) which serves a thinner surface, and the second wire (4) is the wire which brings a web (W2) serving as a thicker body layer. Device according to any of the preceding claims 5, 7 or 10, characterized in that the roller which collects most of the water is provided for suction operating at least at the nip (N). Device according to any of the preceding claims 5-12, characterized in that the device 15 comprises means for moving the rotary shafts of the rollers (1, 2) with respect to one another and consequently for changing the position of the nip (N) in machine direction while driving. Device according to any of the preceding claims 5-13, characterized in that the extra roll (1) which is opposite the turn roll (2) can be: • driven.