NO141904B - PROCEDURE FOR THE MAKING OF ABSORBING PAPER - Google Patents

Description

The present invention relates to a method of the kind which

is stated in claim l's preamble.

A method of this kind is known from US patent no. 3,301,746, where the proposed embossing cloth can be square or diagonally woven and can have an arbitrary specific structure including, for example, plain weave or 1-2 twill weave. According to the aforementioned patent, an embossing cloth with 8-24 stitches per stitch is preferred. cm, and that the filaments have a diameter in the range 0.2 - 0.6 mm.

Sheets of paper produced according to US patent no. 3,301,74 6 using 1-2 twill embossing cloth (hereinafter also referred to as semi-twill textile or semi-twill embossing textile) exhibit properties corresponding, in most respects, to sheets of paper produced using a single-woven, impression textile with filaments of approx. the same diameter, when the semi-cyper textile is installed so that its normal "straight" side is used to impress the uncompacted paper tap. This is due to the fact that the conventional "straight" side of semi-twill fabric, assuming that the fabric has uniform projection heights on its web-contacting side, will form a dot-dash pattern, in which the longitudinal axes of the dash embossments are parallel to the machine's transverse direction and the longitudinal axes of the dot impressions are parallel to the machine direction. The line impressions result from each weft filament which in a repeating pattern is passed under a warp filament and then over the next two warp filaments, while the point impressions come from each warp filament which in a repeating pattern is passed over a weft filament and then under the next two weft filaments on the textile's conventional law. When fiber sheets pressed in at the conventional straight side of a semi-twill textile, as described above, are scraped from the drying cylinder, the dot-dash-protrusion impressions will essentially be aligned between the crepe folds. The crepe folds obtained are therefore essentially uninterrupted across the surface of the sheet. Paper sheets produced using the conventional straight side of a semi-cypress pressing textile exhibit properties substantially similar to paper sheets produced using a single woven pressing textile, i.e. a light, soft voluminous and absorbent paper sheet characterized by even crepe folds that extend essentially uninterrupted across the width of the sheet.

It is one purpose of the present invention to provide

a method of the aforementioned type, by which a soft, voluminous and absorbent paper sheet can be produced, which exhibits improved transverse tensile strength as well as improved softness, surface grip and drapeability, compared to paper sheets produced according to the aforementioned US patent, and this is achieved by using the present method which is characterized by what is stated in claim 1's characterizing part.

Applying the "back" side of a semi-kyper embossing cloth to pattern an uncompacted paper web produces a dash-dot-knot pattern. in which the longitudinal axes of the line indentations are aligned parallel to the machine direction of the paper machine and the longitudinal axes of the dot indentations are aligned parallel to the transverse direction of the machine. The stretch compressions formed from each warp filament being passed in a repeating pattern under a weft filament and then over the next two weft filaments, while the point compressions' are the result of each weft filament being passed in a repeating pattern over a warp filament and then the two following warp filaments on the back of the fabric.

Sheets of paper patterned with the reverse side of such a semi-twill press-in textile will, unlike sheets patterned with either single-woven textile or with the usual straight side of a semi-twill textile, exhibit a diamond or star-shaped pattern after creping. The stretch marks will run across the crepe folds, whereby an increased stretchability is achieved across the machine direction, improved softness, improved surface grip and draping ability, which can also be attributed to the fact that the stretch marks, seen in a direction across the machine direction, will overlap each other . The size of the knot imprinting area on the back of the textile is decisive for how long the line imprints and <p>rib imprints will be, and the proposed knot imprinting area, namely 20-50% of the textile's total surface area, has been shown to give the desired result. A knot impact area of this order of magnitude can be achieved by grinding, as is also known from US patent no. 3,573,164.

To that end; to maximize the beneficial effects of abrading the projecting surfaces on the back of a semi-cyper pressing fabric, it has been found desirable to achieve

a semi-twill fabric with uniform threading heights and with minimal free area on its reverse side for an initial sanding process. Even projection heights allow a greater enlargement of the projection indentation area, while the danger of a complete grinding through of a particular filament is minimized. In addition, if the protrusion heights are uniform before a grinding process is initiated, the resulting indentation sample after grinding will be evenly distributed.

Because the textile used for pressing conditions according to US patent nt. 3.3ol.746 is exposed to elevated temperatures during use, it is desirable to heat-stabilize the textile's dimensions for this to be subjected to a nadgrinding process in order to increase its projection, indentation area. If this is not done, the even pressing surface is obtained by noy-like weaving of the textile and grinding down the web-contacting surface of the textile for use, the textile will tend to warp when its temperature is raised,

whereby most of the benefits obtained from such careful pre-treatment are lost.

A method for processing a dimensionally heat-stabilized, single-woven monofilament polymer fiber fabric with uniform projection heights and minimal free area on each side of the fabric is disclosed in US Patent No. 3,473,576. A single woven textile is produced from selected polymeric warp monofilaments with a relatively high heat-induced shrinkage potential and further by selecting an initial warp monofilament spacing in the fabric according to a mathematical equation shown in the aforementioned US patent no. 3,473,576. <p>olymer insertion monofilaments are selected which have a relatively low heat-induced shrinkage potential and these insertion monofilaments are woven and mechanically processed in the weaving process into a single woven textile with an initial thickness calculated according to a further mathematical formula, which is shown in the aforementioned US patent no. 3,473,576.

After the initial weaving process, the textile thread protrusions are brought to an even height on both sides of the textile and the minimal free area of this is fixed by a heat shrink treatment which maintains the textile in warp tension, which allows it to shrink in the insertion direction. Successive heat treatments are repeated until the monofilament, polymer-fiber single-woven fabric does not shrink further at the treatment temperature, at which point it is said to be "locked in", i.e. no further shrinkage takes place, if the fabric is subsequently subjected to elevated temperatures during use the treatment temperature.

It is important to note that, as a result of the symmetry of the single weave, uniform thread projection height and minimal free area on both sides of the textile are simultaneously achieved when the weaving and heat treatment process according to the aforementioned US patent no. 3,473,576 is used. This is not the case for a semi-twill woven fabric. If a monoEilament, polymer fiber semi-cyper textile is subjected

a heat treatment similar to that described in connection with the aforementioned US patent, the wire protrusions on the conventional

face of the fabric to be in a common plane before the thread protrusions on the back of the fabric have reached a uniform height. Thus, in order for the thread protrusions on the back of the textile to become flat, the textile must be subjected to a further heat treatment. The additional heat treatment, which is necessary to make the protrusion heights on the back side of the fabric even, causes the protrusion heights on the normal front side of the fabric to become non-uniform again.

Therefore, the initial warp filament spacing and thickness for semi-kyper fabric, which is necessary to provide a minimum free area and uniform projection heights on the back of the fabric after heat treatment, must be determined experimentally by trial and error. With regard to the size of the knot impact area on the back of the textile, it should further be noted that such a large knot impact area contributes significantly to the final breaking strength of the dry product, because the large area reduces the risk of tearing the fiber bonds.

The invention must be explained with reference to the attached drawings, in which

Fig. 1 shows a plan section of an enlarged part of a conventional right semi-cyper, monofilament polymer fiber textile seen from the back, ie from the side of the textile which, according to the state of the art, is not normally brought into contact with the web. The monofilament polymer fiber semikyper textile is shown prior to any grinding treatment and prior to use as an endless or continuous textile belt in papermaking or nonwoven fabric manufacturing processes. Fig. 2 is an enlarged cross-section of the semi-twill textile shown in Fig. 1, viewed in the transverse direction (CD) of the machine along the line 2-2 in fig. 1, from which the relatively high and smooth knot surfaces of the warp filaments on each side of the fabric can be seen. Fig. 3 is an enlarged cross-section of the semi-kyper textile shown in fig. 1 and 2, seen in the machine direction (MD) along the line 3 - 3. in fig. 1, which cross-section shows a relatively lower level and the smooth nodal surfaces of the insertion or weft filaments. Fig. 4 is a simplified illustration of an enlarged partial view of an uncreped paper sheet which has been monstered using a conventional straight side of a semi-twill fabric, as shown in Fig. 1-3. The longitudinal axis of the point indentations formed by the warp filaments is arranged parallel to the machine direction. Fig. 5 is a simplified illustration of an enlarged partial view of an unshrunk paper sheet monstered using the reverse side of a semi-warp fabric as shown in Fig. 1-3. The longitudinal axes of the prick indentations formed by the warp filaments

is arranged parallel to the machine direction.

Fig. 6 is an enlarged cross-section of a monofilament polymer fiber, semi-warp textile as shown in Fig. 1-3, seen in the machine direction and taken along a point corresponding to line 2-2

in fig. 1, after the textile has been subjected to a heat treatment process sufficient to form uniform projection heights on the conventional right side of the textile.

Fig. 7 is an enlarged cross-section of the semi-kyper textile

shown in fig. 6, seen in the machine direction taken from a point corresponding to the line 3 - 3 in fig. 1.

Fig. 8 is a simplified illustration of an enlarged partial plan view of an uncreped paper sheet, which is monstered using the conventional right side of a monofilament polymer fiber semi-twill fabric as shown in Fig. 6 and 7. The longitudinal axes of the line indentations formed by insertion or weft filaments are aligned parallel to the transverse direction of the machine> while the longitudinal axes of the dot indentations formed by the warp filaments are aligned parallel to the machine direction. Fig. 9 is a simplified illustration of an enlarged partial plan view of an unshrunk sheet of paper, which has been monstered using the back of a semi-twill fabric as illustrated in Fig. 6 and 7. The longitudinal axes of the line indentations formed by the warp filaments are aligned parallel to the machine direction. Fig. 10 is an enlarged cross-section of a monofilament polymer fiber, semi-cyper textile as shown in Fig. 1 - 3 and 6 - 7, seen in the machine direction and taken along a point corresponding to line 2 - 2 in fig. 1, after the textile has been subjected to a heat treatment process sufficient to form even stitch heights and minimal free area on the back of the textile. It should be noted that at this point the pre-stitching heights on the conventional right side of the textile are no longer even. Fig. 11 is an enlarged cross-section of the semi-kyper textile shown in fig. lo seen in the machine direction and taken along a point corresponding to line 3 - 3 in fig. 1. Fig. 12 is a simplified illustration of an enlarged partial plan view of an uncreped paper sheet, which is monstered using the conventional face of a semi-twill fabric, as shown in Fig. lo and 11. The longitudinal axes of the line indentations formed by the insertion or weft filaments are aligned parallel to the transverse direction of the machine. Fig. 13 is a simplified illustration of an enlarged partial plan view of an uncreped paper sheet which has been monstered using the reverse side of the semi-cyper fabric as shown in Fig. lo and 11. The longitudinal axes of the line indentations formed by the warp filaments are aligned parallel to the machine direction, while the longitudinal axes of the dot indentations formed by the insertion or weft filaments are aligned parallel to the transverse direction of the machine. The dot embossings are present at this stage as a result of the fact that the protrusions on the back of the textile are of uniform height. Fig. 14 is an enlarged cross-section of a monofilament polymer fiber, semi-twill textile, as shown in Fig. lo and 11, set. in the machine direction and taken along a point corresponding to the line 2 — 2 in fig. 1, after the back of the fabric has been sanded down to increase its protrusion-indentation area. Fig. 15 is an enlarged cross-section of the semi-kyper textile shown in fig. 14, seen in the machine direction and taken along a point corresponding to the line 3 - 3 in fig. 1. Fig. 16 is a plan view of an enlarged portion of monofilament polymer fiber, the semi-kyper textile shown in fig. 14 and 15, seen from the back of the textile. Fig. 17 is a plan photograph enlarged approx. 12 times the actual size of an uncreped paper sheet, which is monstered using the back of the semi-kyper fabric, as shown in fig. 14, 15 and 16. The formed monster is similar to that shown in fig. 13, but the dot-line indentations make up a larger percentage of the surface area of the paper as a result of the increased protrusion-indentation area of the textile. Fig. 18 shows an enlarged cross-section of the unshrunk paper sheet according to fig. 17 seen in the machines transverse direction and taken along the line 18 - 18 in fig. 17. Fig. 19 is a plan photograph enlarged approx. 6 times the actual size of a sheet of paper, as shown in fig. 17 and 18 after crimping. The longitudinal axes of the impressions which are visible after shrinking are generally oriented in the transverse direction of the machine, while the total surface of the paper exhibits a star-shaped monster, which is characteristic of the paper sheets produced according to the present invention. Fig. 2o is an illustration of an enlarged cross-section of the creped paper sheet according to fig. 19, seen in the transverse direction of the machine and taken along the line 2o - 2o in fig. 19.

When describing preferred embodiments of the invention,

for the sake of clarity, a special terminology will be used with reference to the features of the monofilament polymer fiber textiles used in paper production and in manufacturing processes for non-woven textiles. The conventional "straight" side of the semi-kyper textiles will subsequently refer to the side of the textile which, according to the state of the art, would normally come into contact with the paper tap, i.e. the side of the semi-kyper textile which would, depending of the special conditions, form one of the press-in monsters shown in Fig. 4 -8 and 12 (assuming that it is a right-facing -1-2 twill cloth).

the previously mentioned figures, the longitudinal axes of the line indentations 9, when present, are aligned parallel to the transverse direction of the machines, while the longitudinal axes of the dot indentations 3, when present, are aligned parallel to the machine direction. The "back" side of the semi-kyper textiles is hereinafter defined as the side that would not normally come into contact with the paper tap according to the state of the art, i.e. the side of the semi-kyper textile that would, depending on its particular condition. forming one of the impression monsters shown in fig. 5, 9, 13 and 17 (assuming that it is a right-facing -1-2 twill cloth). In the previously mentioned figures, the longitudinal axes of the line indentations 8 are aligned parallel to the machine direction, while the longitudinal axes of the point indentations 10, when these are present, are aligned parallel to the transverse direction of the machine.

It should be noted that even if right-facing 1-2 twill cloth is used

for illustration purposes in this description, the benefits can also be obtained using left-facing 1-2 twill, which is woven as a mirror image of right-facing 1-2 twill.

Fig. 1 represents an enlarged plan view of a portion of a conventional right-facing, monofilament polymer fiber, 1-2 twill, as seen from the rear. The Semikyper textile shown in fig. 1 has not been applied to a paper machine, nor has it been greased for any special grinding treatment. The warp monofilaments 1 are aligned parallel to the machine direction,

while the insertion or weft monofilaments 2 are aligned parallel to the transverse direction of the machine. In a preferred

embodiment of the present invention, the press-in textile in fig. 1 8-24 stitches/cm and is formed from monofilament polymer fibers with diameters in the range o.2o - o.64 mm. Both warp-

and the insertion monofilaments may, but need not necessarily, have the same diameter. Fig. 2 and .3 are cross-sectional views of the semi-twill textile shown in fig. 1 are respectively seen in the machine's transverse direction and machine direction. The forward stitches formed at the crossing point of the warp filaments 1 and the insertion filaments 2 do not lie in the same plane on either the front or the back of the textile. As can be seen from fig. 2 and 3, the warp filaments 1 are at a relatively higher level than the insertion filaments 2 on both sides of the textile. This is referred to in the present description as a "high warp" condition for the textile.

Fig. 4 is a simplified illustration of the pre-stitch-indentation sample that would result in a semi-twill fabric as shown in Fig. 1-3 was installed so that the conventional front side of the fabric was used to emboss an uncreped paper tap, manufactured according to US Patent No. 3,301,746. The dot indentations 3, which are visible on the surface of such an unreinforced paper sheet after indentation, form a monster corresponding to the protrusions 4 in the warp filament 1 on the conventional face of the textile. Since the dot protrusions 3 are formed by the warp filaments 1, the longitudinal axes of the dot pressings will be aligned parallel to the machine direction. The protrusions 7 formed by the insertion filaments 2

on the conventional face of the textile, do not form a corresponding indentation in the uncompacted paper tap due to the fact that they are at a lower level in relation to the warp filament productions 4.

Figure 5 shows the knot crimp sample that would occur if an uncompacted paper tap, made according to US Patent No. 3,301,746, was embossed using the back of a crimp fabric, as shown in FIG. 1 - 3. Because the warp filaments 1 are at a relatively higher level than the insertion filaments 2 on the back of the textile, only the tops of the insertions 5, formed by the warp filaments, would be pressed into the paper tap during the pressing process. As the warp filaments 1 run in the machine direction, the formed monster would consist of several relatively long stretch compressions 8, in which the longitudinal axis of the compressions is aligned parallel to the machine direction.

The indentation sample shown in fig. 5 differs from the indentation sample shown in fig. 4 in two important respects. Firstly,

as each warp filament 1 is lined over two insertion filaments 2

on the back side of the semi-kyper textile compared to only one insertion filament 2 on the front side of the textile, the length of the insertion will be approx. 2 times as long when the web is pressed in with the back of the fabric. Second, when a paper rooster embossed with the monster shown in fig. 5 is removed from the drying cylinder by means of a conventional scraper, a star-shaped monster is impressed on the surface of the paper, while when the paper tap is embossed with the monster shown in fig. 4, is removed from the drying cylinder by means of a conventional scraper, a normal crepe pattern is obtained in which the crepe tops are essentially unbroken across the width of the sheet. This distinctive difference in the finished product seems to result from the fact that the path shown in fig. 4 after to the dryer only at interrupted intervals, i.e. of the dot indentations 3, which indentations are not sufficiently long to overlap each other in the machine direction. The paper tap shown in Fig. 5, on the other hand, is attached to the drying cylinder in a continuous manner, i.e. by the line indentations 8, which indentations are sufficiently long to overlap each other in the machine direction.

Based on the prior art, particularly US Patent No. 3,473. 576, it is recognized that smooth web liners and maximum drying efficiency cannot be obtained with fabrics having a rough or uneven web contacting surface. Smooth web transfer is particularly desirable where, as in the case of the papermaking process shown in US Patent No. 3,310,746, the impression textile is of product characterizing importance. It is therefore desirable to utilize imprinted textiles with even stitch heights and minimal free or intermonster area on

the side of the textile that is brought into contact with the uncompacted paper tap. Because such impression textiles are exposed to elevated temperatures during use, it has also been found desirable to heat stabilize the dimensions of such textiles for use in order to prevent warping.

It is important to note that, as a result of the symmetry in a single-woven textile, uniform pre-stitching heights and minimal free area are simultaneously achieved on both sides of the textile, when this is subjected to the heat treatment process, as shown in US patent no. 3,473,576. This is not the case for a semi-woven fabric. If a monofilament polymer fiber semi-twill fabric is subjected to the heat treatment process, as disclosed in US Patent No. 3,473,576, the embossments 4 and 7 on the conventional face of the fabric will become coplanar with the embossments 5" and 6 on the back of the fabric .In order that the preparations 5 and 6

on the back of the textile must now have even heights, the textile must be subjected to a further '. heat treatment. The further heat treatment will, in turn, cause the heights of the cutouts 4 and 7 on the conventional front side of the 1-2 twill fabric to become uneven again.

Therefore, the initial warp-filament distance and thickness must be

a semi-cyper textile required to produce the free area and uniform cutting heights on the reverse side of the textile after heat treatment is determined experimentally.

It is preferred that a mbnofilament polymer is used

fiber, semi-cypress textile that is produced

by choosing warp monofilaments with a relatively high heat-induced shrinkage potential in the range lo - 3o%, preferably approx. 16%. After the selection and the distance between the warp monofilaments, polymeric insertion monofilaments are selected which have a relatively low heat-induced shrinkage potential in the range of 2 - 8%, preferably approx. 4%. The heat-shrink treatment takes advantage of the mentioned shrink properties for the warp and insertion filaments. The heat shrink treatment involves subjecting the initially raised textile to a series of heat applications while it is stretched and secured at its ends in the longitudinal or warp direction,

while it can shrink freely in the weft direction.

The heat shrink treatment is applied appropriately fo* it initially

woven semikyper textile, while the textile is mounted as an endless belt on a finishing table, as the conventional

used when finishing metal Fourdrinier wires. A conventional wire finishing table consists of 2 adjustable rollers for supporting, stretching and driving the wire or textile to be finished as an endless belt. The heat shrinkage can conveniently be induced by an infrared source mounted as a unit above and across the initially woven fabric. The infrared source heats areas of the initially woven textile, while the textile slowly rotates on the rollers on the wire processing table. Heat is supplied to the textile in successive treatments for 5 - 4o s, preferably 15 s per treatment. The textile temperature during the successive heat applications gradually approaches the softening point of the selected mono-filament polymer fibres. Repeated passes are used to avoid sudden shrinkage which will cause curling of the fabric, consecutive heat treatments are repeated until the stitch heights on the back of the fabric reach uniformity, which condition also

corresponds to the minimal free or inter-stitch area if the original warp-filament distance and thickness of the fabric have been correctly determined. A semi-twill textile subjected to the heat treatment process mentioned above, although not "locked up" as is the case for a single weave textile subjected to such a heat treatment process, is dimensionally heat stable at the temperatures used in the web imprinting process disclosed in US Patent No. 3,301,746.

The fiber temperatures in the successive heat treatments are raised to a maximum temperature immediately below the softening point of the selected fibres. E.g. the heat treatment temperature used for "TREVIRA" fibers is 192 - 2o5°C, preferably v approx. 19o°C. For dimensional heat stability for use as an impression textile according to US patent no. 3.3ol.746, a sufficient number of consecutive heat treatments or passes are used to ensure that the mono-filament polymer fibres, which make up the textile structure, have been at the highest heat treatment temperature for a total time of 15 - 12o s.

Against all expectations, a weaving procedure in which po-

lymer warp and weft monofilaments are only woven as tightly as

possible to ensure a minimal free area, does not result in a textile with uniform pre-stitching heights after the heat treatment or when used in web drying systems. Polymeric fibers generally exhibit heat shrinkage and if such a close weave procedure is attempted, which includes an initial minimum distance in both polymeric warp and weft filaments, the resulting heat treated and heat stabilized fabric will exhibit non-uniform stitch heights. Therefore, according to a preferred embodiment of the present invention, an initial warp filament spacing in the fabric and an initial thickness of the semi-kyper fabric are determined experimentally by a trial and error method to account for the heat-induced crimp, which finds place during the dimensional heat stabilization process described above.

Figures 6 and 7 are enlarged cross-sections of a monofilament polymer fiber, semi-cyper textile, as shown in fig. 1-3

after the heat treatment process, as described above,

has begun. Fig. 6 is seen in the transverse direction of the machine and taken along a point corresponding to the line 2 - 2 in fig. 1, while fig.

7 is seen in the machine direction taken along a point corresponding to line 3 - 3 in fig. 1. Figs. 6 and 7 represent an intermediate state for the textile, which takes place during the heat treatment process, for uniform pre-stitching heights and minimal free area on the back of the textile are achieved. Fig. 6 represents

the condition that occurs when the warp filaments 1 show a tendency to draw closer to a straight line as a result of the heat-induced shrinkage. The tendency of the warp filaments 1 to take on a lower total amplitude, as a result of the heat-induced shrinkage, forces the insertion mono-filaments 2 on the conventional face of the fabric inwards and the insertion filaments 2 on the back of the textile outwards, as the insertion mono-f the ends of the elements are not fixed. This is more clearly illustrated in fig. 7, in which the insertion monofilaments 2 tend to wrap more completely around the warp monofilaments 1. As a result, the protrusion 7 formed by the insertion filaments 2 will become coplanar with the protrusions 4

formed by the warp mono-filaments 1 on the conventional for-

side of the textile. It should be noted that at this particular point the precuts 5 formed by the warp monofilaments 1 remain at a relatively higher level than the precuts 6 formed by the weft monofilaments 2 on the back side of the fabric.

Fig. 8 is a simplified illustration of an enlarged plan view of an unreinforced paper sheet, made in accordance with US Patent No. 3,310,746, which paper sheet is embossed using the conventional face of a monofilament polymeric fiber, semi-cyper textile, which shown in fig. 6 and 7. The indentation monster caused by the protrusions is similar to those shown in fig. 4, in which the point indentations 3 formed by the protrusions 4 of the warp monofilament 1 on the conventional face of the textile are shown,

but the line indentations 9 formed by the protrusions 7 of the insertion monofilaments 2 are also present, because the insertion monofilaments 2 are aligned parallel to the transverse direction of the machine, the longitudinal axes of the point indentations 9 will also be aligned parallel to the transverse direction of the machine.

Fig. 9 is a simplified illustration of an enlarged partial plan view of an uncreped paper sheet made in accordance with US Patent No. 3,301,746, which uncreped paper is embossed using the reverse side of a semi-twill fabric, as shown in fig. 6 and 7.

In the same way as in fig. 5, the longitudinal axes of the point depressions 8 formed by the protrusions 5 of the warp monofilaments 1, are aligned parallel to the machine direction.

As for paper sheets embossed with monster twist in fig. 4, paper sheets, in which embossing patterns shown in fig. 8, exhibit a basic shrink regularity in which the shrink folds extend substantially in an unbroken manner across the entire width of the sheet. The addition of the dot indentations 9 on the embossed monster does not change the fact that the embossed paper sheet adheres to the drying roller only at interrupted intervals corresponding to the distance, in the machine direction, of the dot indentations 3. Paper embossed with the monster shown in fig. 9, on the other hand, exhibits a diamond-encrusted monster, which is characteristic of the sheets made according to the present invention, when these are scraped from the drying roll.

To achieve even cutting heights and minimal free

area on the back of a semi-twill fabric, as shown in fig. 6 and 7, as they are desired in practice

of the present invention, the heat treatment process is continued until a state corresponding to that shown in Figures 10 and 11 is achieved. Fig. lo is seen in the transverse direction of the machine taken along a point corresponding to the line 2 - 2 in fig. 1, while fig. 11 is seen in the machine direction taken at a point corresponding to the line 3 - 3 in fig. 1. Heat-induced shrinkage of the warp monofilaments 1, as shown in fig. lo, has formed a smaller total amplitude, which has caused the insertion mono-filaments 2 on the back side of the fabric to move upwards and the insertion mono-filaments 2 on the conventional front side of the fabric to move downwards. As can be seen from fig. 11, the insertion filaments 2 are not different from the warp mono-

the filaments 1, subjected to tensile stress and they will tend to warp more completely around the warp mono-filaments 1 located on the conventional face of the fabric. At the same time, the insertion monofilaments 2 will show a tendency to degree

show to fold itself around two adjacent warp mono-filaments 1 located on the reverse side of the fabric. As a result, the heights of the warp mono-filament protrusions 5 on the back side of the fabric and the insertion mono-filament protrusions 6 on the back side of the fabric will become uniform, while the heights of the insertion mono-filament protrusions 7 on the conventional face of the fabric and the warp monofilament protrusions 4 on the conventional face of the fabric become non-uniform. If the initial warp-filament distance in the weave and the initial thickness of the semi-twill fabric were correctly determined taking into account the heat-induced shrinkage, the conditions shown in fig. lo and 11 be obtained,

i.e. a dimensionally heat-stabilized semi-twill fabric with even stitch heights, as well as minimal free area on its reverse side.

Fig. 12 is a simplified illustration of an enlarged floor plan. of an uncreped paper sheet made according to US Patent No. 3,311,746, which uncreped paper sheet is embossed using the conventional face of a semi-twill fabric as shown in fig. lo and 11. The embossing sample is substantially similar to that shown in fig. 8, but the dot indentations 3 formed

of the warp mono-filament protrusions 4 on the conventional face of the fabric are no longer present, due to the fact that the warp mono-filament protrusions 4 are at a relatively lower level than the insertion mono-filament protrusions 7 on the conventional face of the textile. Sheet of paper embossed with the monster shown in fig. 12, shows after creping properties which are essentially equivalent to sheets embossed with the monsters shown in fig. 4 and 8.

Fig. 13 is a simplified illustration of an enlarged partial plan view of an uncreped paper sheet made according to US Patent No. 3,311,746, which uncreped paper is embossed

using the reverse side of a semi-twill fabric, as shown in fig. lo and 11. The line impressions 8 formed by the warp-filament protrusions 5 on the back of the textile are essentially the same as shown in fig. 8, but the dot indentations 9 formed by the insertion monofilament protrusions 6 on the back of the fabric are also present, due to the fact that the warp filament protrusions 5 and the insertion filament protrusions 6 on the back of the fabric are of equal height . Paper sheets made using the back of a semi-twill fabric, as shown in fig. lo and 11 for embossing purposes exhibit a star-shaped appearance after creping, which surface appearance is characteristic of paper sheets produced according to the present invention. As the protrusion-indentation area on the back side of such a mono-filament polymer fiber, semi-kyper textile is increased, the star-shaped monster has become more predominant.

It has been found that increasing the protrusion-indentation area

on the back of such a textile also provides certain unexpected advantages in the properties of the finished sheet. These unexpected properties manifest as a greater stretch in the transverse direction, as well as improved softness, o verface1 "grip" and drape. However, increasing the spring indentation area on the conventional face of a corresponding monofilament polymer fiber semi-twill indentation textile does not provide similar improvements in the properties of the finished sheet. This is also the case for single-woven impression textiles. It has thus been unexpectedly found that the above-mentioned improvements in the properties of the sheet can only be obtained by

increase the protrusion indentation area on the back of a conventional mono-filament polymer fiber semi-twill indentation fabric.

A method of increasing the projection indentation area of a monofilament polymer fiber textile is shown in US Patent No. 3,573,164, whereby the projection surfaces are ground down with a fine abrasive medium to improve web transfer, web drying, web product properties and overall machine operation. In a pre-

drawn embodiment of the present invention is brought mono-filament polymer fiber, the semi-kyper impression textile,

which is to be ground, to the state shown in fig. lo and 11,

i.e. even projection heights and minimal free area on

its back, for some sanding. Even though the grinding treatment shown in US patent no. 3,573,164 will give uniform stitch heights on a textile, which originally did not have uniform stitch heights, it is very desirable in a preferred embodiment of the present invention to use a textile which from the beginning has uniform cutting heights on the side to be treated, in order to minimize the possibilities of a complete grinding through of one or more mono-filaments during the grinding process. Therefore, the back of a textile, as shown in fig. lo and 11, are subjected to a more extensive grinding process and thus give a greater increase in the protrusion-indentation area than is permissible with a textile which initially has non-uniform protrusion heights on the side to be treated.

As mentioned earlier, it has been found desirable that the mono-filament, polymer fiber textiles are dimensionally heat stabilized for use. If this is not done, warping can occur after the textile has been used and exposed to elevated temperatures. Thus, in order to achieve the full benefits that can be obtained from the grinding process, it is highly desirable in a preferred embodiment of the present invention that the semi-kyper textile is dimensionally heat stabilized according to the previously described method before a grinding process is started.

According to a preferred embodiment of the invention, the back side of a monofilament, polymer fiber, semi-cotton impression textile is subjected to a treatment, where the textile's production surface is ground under

use of either wet or dry sandpaper with an effective sanding grain size in the range of 3oo - 5oo mesh, as sanding medium. The abrasive medium can be mounted on a drum for a rotating treatment of the textile's surface. The grinding process can be carried out during a continuous showering of the textile with water or other cleaning or smearing fluid, e.g. light oil, to remove off-

towed particles and to promote the polishing operation.

A total protrusion-indentation area of 20 - 50% of the textile's total surface area, on the treated surface, is preferred. An increase in the projection surface area over 5o%-

the level significantly increases the danger of a complete

grinding of special monofilaments and can easily get an odeleg-

changing effect on the useful life of the textile.

It is also preferred to form a smooth and polished surface

flat on the protrusions on the back of the mono-filament polymer fiber, the semi-kyper textile. To achieve this, the grinding operation described above can be carried out in several steps. E.g. the initial grinding can be carried out with a grinding medium with an effective grinding grain size of approx. 3oo mesh and this initial sanding operation can be followed by an abrasive polishing treatment using water-lubricated, wet sandpaper with an effective sanding grain size of approx. 5oo mesh. Polishing abrasives, such as talc, polishing red and burlap can also be used for a further polishing of the cutting surfaces.

Figs. 14 and 15 are enlarged cross-sections of a monofilament poly-merfiber, semi-cyper textile, as shown in Figs. lo and 11, after the back of the fabric has been dragged to increase its projection-indentation area to 2o - 56% of the total surface area of the textile, measured in the plane of the projection. Fig. 16 is a basic section of an enlarged part of the textile shown in fig. 14 and 15, seen from

the back of the textile. The textile illustrated in fig.

14 - 16 represent a preferred form,

in which even projection heights and minimal free area were on the back of a textile for a grinding process to begin. One inherent advantage associated with maintaining uniform protrusion heights and minimal free area before the grinding process begins is the uniformity of the protrusion indentation pattern, which is obtained after the grinding process is complete. A final move is illustrated in fig. 16.

Figs. 14 and 15, viewed respectively in the transverse direction of the machine and the machine direction, show the textile profile which is brought into contact with an uncompacted paper web when the textile is used for embossing purposes, according to US patent no. 3.3ol.746. The warp filament protrusions 5 and the insertion filament protrusions 6, as shown in fig. 10 and 11, is drawn off to give the plateau-like warp filament protrusions 5' and insertion filaments 6' shown in fig. 14 and 15. In addition to improving the web transfer and web drying properties, the plateau-like projection surfaces 5' and 6' will press in an uncompacted paper tap at a uniform depth and thus form a more distinct embossing pattern.

The moist paper tap carried on an embossed textile according to the present invention can be thermally preheated by passing hot gases, for example air, through the moist paper tap and the embossed textile. A suitable apparatus for drying the moist paper tap is shown in US Patent No. 3,303,576. Although the manner in which the thermal drying is carried out is not critical, it is critical that the relationship between the moist web and the embossed textile is maintained once it is established.

According to US Patent No. 3,301,746, the thermal drying is operated to give a fiber consistency in the moist paper stock of 30 - 80%, preferably 40 - 80%. for said US patent no. 3.3ol.576 further states that for fiber coaistencies less than approx. 3o%, the desirable balanced sheet properties, such as softness, bulk and absorbent capacity will suffer as a result of the sheet and its fibers being too moist and yielding taking place during the embossing step. In the previously mentioned patent it is also stated that a reduction to fiber consistencies over approx. 3o% prevents the development of effective wear resistances in them. embossed paper sheets.

Based on US Patent No. 3.3ol.746 and

US Patent No. 3,926,716 it is known that fiber

consistencies between 3o% and 98% for transferring the web to the drying roller is possible without adversely affecting the breaking strength of the so •

is led to produce sheets of paper. Fiber consistencies above cn. 3o% is obtained by spraying the surface of the dryer for web transfer down an aqueous solution of polyvinyl alcohol adhesive, which is characterized by a degree of hydrolysis in the range 80 - 9o%

and a viscosity in a 4% aqueous solution at 20°C that exceeds approx. 2o centipoise. 2oo - l.ooo y polyvinyl alcohol (dry weight) is applied per tonnes of paper produced (dry weight).

Imprint of the textile projection monster in the damp lane

by pressing the dried web against a relatively non-yielding surface, for example an unheated steel roll or Yankee drying surface, while the dried web is still carried

on the imprinting textile, results in a sheet of paper which has impressed on its surface to a depth of at least 3o% of its machine glossfi thickness with protrusions of the imprinting textile. Machine-polished thickness refers to the thickness of the paper sheet

taken directly from the Yankee dryer for creping. Thus in-

the projection surfaces 5' and 6' of the press, shown in fig. 16-14

in a preferred embodiment of the present invention, to a uniform depth of at least 30% of the machine-polished thickness of the unreinforced paper sheet. The necessary pressure to impress the monster of the imprinting textile can be provided, in a preferred embodiment of the present invention, by one or more pressure rollers acting on the imprinting textile to press the projection of the textile into the surface of the pre-dried web and to

press the dried web surface under the protrusions against the face of the Yankee tire cylinder.

It must be understood that it is critical for the implementation of the agreement

invention that the embossing step, described above, is the first essentially mechanical compaction step to which the paper tap is subjected during sheet formation and drying.

Fig. 17 is a photograph of an enlarged partial plan view of an uncreped paper sheet made according to US patent no.

3.3ol.746 using the back of a semi-twill fabric, as shown in fig. 14 - 16, to emboss the uncompacted paper cock. The protrusion-indentation sample obtained is essentially the same as that shown in fig. 13. However, the line indentations 8, formed by the warp filament protrusions 5', and the point indentations 10, formed by the insertion filament protrusions 6', constitute a greater percentage of the surface area of the sheet, as a result of the increased size of textile - the protrusions. In addition, the indentations 8 and 10 are more distinct due to the fact that they are of substantially uniform depth and formed by the plateau-like surfaces of the protrusions 5' and 6'.

Fig. 18 shows an enlarged cross-section of the unreinforced paper sheet according to fig. 17, seen in the machine direction and taken along the line 18 - 18 in fig. 17. Fig. 19 is a photograph of an enlarged plan view of a creped paper sheet made according to US Patent No. 3,301,746 using the chin side of a semi-twill fabric, as shown in Fig. 14 - 16, to emboss the uncompacted paper tap for creping. The longitudinal axes of the indentations 11, which are visible after crimping, appear to be oriented generally in the transverse direction of the machine. Different from paper sheets made according to US Patent No. 3,301,746 using either similarly treated single-weave indentation fabric or the conventional face of similarly treated semi-twill indentation fabric, the total surface of the paper exhibits a diamond-shaped monster instead of smooth, unbroken crepe wrinkles that extend across the width of the sheet. Fig. 2o is an illustration of an enlarged cross-section of a sheet of paper according to fig. 19 seen in the machine direction and taken along the line 2o - 2o in fig. 19.

Is finished sheet of paper, as shown in fig. 19 and 2o, produced

according to the present invention, exhibits improvements in transverse elasticity, softness, surface "grip" and drape, which cannot be obtained by the papermaking process shown in US Patent No. 3,301,746 when a similarly treated single -woven textile or when the conventional surface side of similarly treated semi-kyper textile is used to emboss an uncompacted paper web for creping. Focoking the projection-indentation area of a single-weave fabric or the conventional face of a semi-twill fabric, although improving web transfer and web drying properties, will not provide the improvements in cross-direction stretch or elasticity, softness, surface "grip" and draping, which is achieved by increasing the projection indentation area on the back of a semi-twill indentation fabric.

From the foregoing general and specific description of the present invention, it is apparent that the critical procedure to be performed is forming an uncompacted paper web having a specified range of fiber consistency and imprinting this with the protrusions on the backside of a mono-filament polymer fiber, semi-cyper - indentation textile, where the textile has a projection indentation area, which constitutes 2o - 5o% of the total surface area of the back of the textile, measured in the plane of the projections. Paper web formation and pre-drying techniques along with embossing for drying and creasing procedures can be varied by one skilled in the art to provide specific papers for different applications. By the method described above, creped paper sheets can be produced which exhibit a star-shaped surface appearance, composed essentially of cellulose fiber and with a basis weight in the range of 8-65 g/m 2 and which exhibit a repeated pattern of discrete pressed-in areas.

In order to demonstrate the improved properties of the finished product made in accordance with the present invention, a series of experiments were conducted to compare the properties of paper sheets made according to US Patent No. 3,301,746 using different sides of a monofilament -polymer fiber, semlkyper textile. The paper machine conditions were maintained constant throughout the test series, except for the pressing textile.

A pulp consisting of 50% soft wood sulphate cellulose and 50% wood sulphite cellulose was used throughout the series of experiments.

An adhesive coating was applied to the surface of the Yankee cylinder using a roller glue valve with a mesh opening of approx.

4o mesh and which rotated at a linear peripheral speed

about. 2.7 m/min in an open glue vat, and then sprayed the glue picked up by the wire cloth roller onto the surface of the Yankee drying cylinder by means of a series of air jets arranged inside the glue roller, which jets operated at an air pressure of o 5.25 kg/ cm 2.

The adhesive used was purchased under the name "Peter Cooper IX, (Peter Cooper Corporation of Gowanda). The applied mixture contained one part adhesive and 99 parts water. unwoven at the outlet slip and adhered to the surface of the Yankee cylinder, using the adhesive coating described above.

The dry creped sheet was removed from the Yankee drying cylinder

using a conventional scraper, so that the finished product had a 12% stretch as shrink folds.

Two separate monofilament polymer fiber, semi-kyper textiles were used during the trials. The textiles were both 31 (machine direction) and 28 (cross direction) mesh and comprised of warp and weft monofilaments with a diameter of 0.45 mm. One of the fabrics was woven so that its back side was the side that was brought into contact with the web surface and the other was woven so that its conventional front side was brought into contact with the web. Upon receipt, both textiles had a configuration similar to that shown in fig. lo and 11, i.e. the heights of the warp filament protrusions 5 and the weft filament protrusions 6 on the back of each textile were approximately equal, while the warp filament protrusions 4 were at a lower relative level than the weft filament protrusions 7 on the conventional face of each textile.. In order to isolate the effect of the pressing textile on the properties of the finished sheet, the textiles were installed in sequence on the same paper machine in the received condition and the sheets were produced

filed according to US patent no. 3.3ol.746.

The textile, woven so that its back side formed the web compacting surface, was initially found to have a protrusion area of approx. 21.2% in the original state, while the fabric, which was woven so that its conventional face formed the web compacting surface, was found to have a projection-indentation area of approx. 23.4%.

Data obtained from paper samples prepared using the indentation textile with its back side in contact with the uncompacted paper web are set forth below under Example I.

Data obtained from paper samples prepared using the indentation textile with its conventional face in contact with the uncompacted paper web are set forth below under Example II. Apart from the embossing textiles, the paper machine conditions were unchanged for example I and II.

To show the effect of increased protrusion-indentation area

on the web which is brought into contact with the embossed textile, each textile was sanded according to US Patent No. 3,573,164. The protrusion-indentation area on the back of the textile became

brought into contact with the track surface, was increased from approx. 21.2%

to what 28.4%, while the projection-indentation area on the textile, whose conventional face was brought into contact with the web's surface, was increased from approx. 23.4% to approx. 34.1%. These trials were repeated while all paper machine conditions were kept constant except for the textiles' increased protrusion-indentation-

area. Results of determinations made on sample paper sheets obtained during each trial are tabulated below as Examples III and IV: The data given under Example III are taken from sample sheets prepared using the semi-cyper impression textile, the reverse side of which was brought into contact with the uncompacted paper web, while the data reproduced under Example IV are taken from sample sheets prepared using the semi-kyper fabric, the conventional face of which was brought into contact with the uncompacted paper web.

Finally, the protrusion-indentation area of each textile was further increased according to US Patent No. 3,573,164, until the textile, the back side of which was brought into contact with the web, achieved a total protrusion-indentation area of 37.3%, while the textile, whose conventional face was brought into contact with the web, achieved a total protrusion-indentation area of

4o.o%. The experiments were repeated while all paper machine conditions were kept constant, apart from the projection-indentation area of the textiles. The results of the provisions continued. trial paper sheets taken during each trial are reproduced under Examples V and VI. The data that is. given in V is taken from paper sheets made using the semikyper textile, the back side of which was brought into contact with the uncompacted paper web, while the data reproduced in Example VI is taken from paper sheets made using the semikyper textile, the conventional front side of which was brought into contact with the uncompacted paper web.

The thickness of the paper sheet at 12.4 g/m2, as tabulated in the following examples, is the thickness of the sheet when it is subjected to an application pressure of 12.4 g/mf

The breaking loads in the machine direction (MD) and in the machine cross direction (CD), as tabulated in the following examples, are given as the force expressed in g/cm that a paper strip can withstand before breaking, using a clamping length of lo cm and where the sample is respectively cut out in the MD and CD direction. The measurements were carried out with a 'Thwing-Albert Tensile Tester' (Thwing-Albert Instrument Company, Phildelphia, Pennsylvania).

The percentage tensile data, tabulated in the examples below, were determined simultaneously with the determination of the fracture thickness in the MD and CD directions, respectively, as described above.

A Thwin-Albert Handle-O-Meter, Catalog No. 211-3 of the Thwing-Albert Instrument Company, Philadelphia, Pennsylvania, was

used to measure a combination of stiffness and sliding friction for papi.L\>rovene. A high "Handle-0-Meter" or "H-O-M" reading indicates a lack of blubber and is therefore undesirable. A lower H-O-M reading indicates a lighter sheet. Two 11.4 x 11.4 cm paper

samples were placed side by side over the 0.6 cm wide "Handle-0--Me^er" slot provided below the blade of the unit.

To determine the "Handle-0-Me'cer" in the machine direction sheets, the paper samples were aligned parallel to the "Handle-O-Meter" knife. To determine "Handle-0-Meter" readings in the transverse direction,

the machine direction of the sample sheets was arranged perpendicular to the "Handle-O-Meter's" knife. Readings obtained directly from standard 5o m ammeters mounted on the "Handle-O-Meter" are reproduced in the following examples.

In order to quantify the sheet properties, which relate to surface "grip" and drape, it was necessary to refer to the principles of textile investigation. Textile handling, as the name suggests, concerns the grip of the material and thus depends on both feeling and handling. When the textile's handling is assessed, the combination of stiffness or laxity, hardness or softness and roughness or softness is used. Draping has another meaning and broadly refers to the textile's ability to assume an appealing appearance when used. Experiments from the textile industry have shown that the stiffness of the textile is the key factor in the study of handling and draping.

An instrument designed by the textile industry to measure stiffness is the Shirley Stiffness Tester. To compare the drape and surface—"grip"—properties of the paper samples produced utilizing the different sides of a semi-twill impression fabric, a "Shirley Stiffness Tester" was constructed to determine the "boynings length" of the paper samples and then to calculate "Boynings stiffness" and "Boynings modulus" values.

The "Shirley Stiffness Tester" is described in ASTM Standard Method No. 1388.. The instrument's horizontal platform is supported by two plastic side pieces. Dis.se .side pieces have engraved index lines for a standard boyning angle of 41.5°. Attached to the instrument is a mirror, which makes it easy for the operator to

view both index lines from a suitable position. The instrument must be graduated in cm. The scale can be used as a template for cutting the test pieces to the correct size.

To perform the test, a rectangular strip of 15.2 x 2.54 cm is cut out of the paper to the same size as the scale, and both the .-scale and the sample are transferred to the platform with the sample on the underside. Both are slowly pushed forward. The paper strip will begin to spill over the edge of the platform as the scale and sample are advanced. The movement of the scale and the sample continues until the suspension of the sample, seen in the mirror, intersects both index lines. The degree of overhang "^ " can be immediately read from the scale mark ring on the opposite side of the zero line, which is engraved on the side of the platform.

As a result of the fact that the paper gets a permanent deformation after it has been subjected to such a stiffness determination, 4 individual test pieces were used to determine the stiffness of the paper along a given axis and the average value for the stiffness in a given direction was calculated. The test pieces were cut in both the machine direction and the machine's transverse direction, and one was cut across the CD+3o O axis and one pa o across the CD+13 5 o axis. From the collected data both along and perpendicular to each of the above-mentioned axes, the overhang value "\" was calculated for the relevant paper sample.

The bending length, "c", is defined in this experiment as the length of paper that will bend under its own weight to a given extent. This is a measure of the stiffness that determines the drape property. This is calculated as follows:

"c" = " i" cm x F(0) where

and

= the average overhang value for the relevant paper height, determined as indicated above.

For the "Shirley Stiffness Tester" the angle © = 41.5° at which angle f(ø or E(41.5°) = o.5. Therefore, the calculation given above is simplified to:

Boynings stiffness, "G", is a measure of the stiffness associated with handling. Calculation of Boynings stiffness, "G", in the present case is as follows:

"G" = o,l x (the basis weight of the paper g/m 2)x "c" mg cm,

where "c" is the bending length of the relevant paper sample, determined as stated above, expressed in cm.

The bending modulus, "q", reproduced in the following examples,

is independent of the dimensions of the examined sample strip and can be regarded as the "internal stiffness" of the material. This value can therefore be used to compare .. the stiffness for materials with different thicknesses. For these calculations, the thickness of the paper sample must be determined at a pressure of o o.o7 kg/cm 2.

The bending modulus, "q", is given by:

where "q" is the bending stiffness of the relevant paper sample, as indicated above, expressed in mg cm, and "g" is the paper thickness expressed in mm, when the paper ex-

is set for a pressure of °o,o7 kg/cm 2.

The results of the determinations carried out on the paper sample sheets, prepared according to the methods described, are indicated in the following examples expressed as bending modulus, "q", which has relevance with regard to both drape and surface "feel". A low bending modulus corresponds to an increased drape and possibly also an improved surface "grip".

The protrusion indentation areas discussed in the examples were determined by making an indentation with a pressure-sensitive paper in each of four areas on the surface of the indentation textile, which was brought into contact with the web, in each of the examples. Magnified photographs were taken of each of the four impressions, and a "unit cell" of the protrusions, i.e., a repeating monster of protrusions, was enclosed in each photograph. The total area of enclosed "unit cells" and the total area of the protrusions within each such "unit cell" were then measured and the result expressed as % protrusion area. The mean value for four separate "single cells" designated as protrusion-indentation areas for the particular example.

In the examples below, the final sheet properties of the paper samples prepared in accordance with the present invention are compared with the sheet properties of paper samples prepared using the conventional face of a corresponding imprint textile, for different stages of textile processing.

The data given in the examples clearly show the advantages of the present invention in the production of a paper sheet, which is characterized by having significantly improved elastic properties in the transverse direction, improved softness, surface "grip", and drape.

Claims (2)

1. Process for the production of a soft, voluminous, absorbent paper sheet, in which an uncompressed paper web with a uniform basis weight of 8 - 62 g/m 2 is formed, where the uncompressed paper web is supported on and embossed with a line-dot-knot pattern by using a 1-2 twill embossing cloth with 8-24 stitches per cm., which is formed from filaments with a diameter of 0.2 - 0.6 mm, and then dry and crimp the resulting paper sheet, characterized in that the paper tap rests against the back of the 1-2 twill embossing cloth and that a cloth is used if the knot imprint area on the back of the cloth constitutes 20 - 50% of the total surface area of the cloth, and that the paper tap is dried ter- misc to a fiber consistency of 30 - 98%, preferably 40 - 98%, which drying step is optionally preceded by a molding step during which the paper tap is forced to adapt to the pattern of the embossing cloth and that the line-dot-knot pattern (8,10) is embossed in the uncompressed web by using the cloth in such a way that the longitudinal axis of the line marks (8) in the pattern runs parallel to the machine direction of the paper web. 2. Method according to claim 1, characterized in that the pre-dried web during the embossing step is pressed against a non-relenting cylindrical surface by means of the embossing cloth in such a way that the cloth's knot pattern is embossed into the paper surface to a depth that constitutes at least 30% of its machine polished thickness.