Patterned paper and a method for manufacturing such

Abstract

The invention relates to a multi-layered soft paper web, and a method for forming such. A multi-layered soft paper web consists of at least one layer, showing basis weight variations in a pattern. A base-layer of a fibre furnish is firstly formed on a wire (2), whereupon at least one top layer is deposited on top of the base-layer, which is supported by a wire or the like (3, 13, 113, 1113) under the applying of the top layer, whereby the top layer is deposited with a fibre suspension jet, and the hereby deposited top layer is formed with twin wire technology. A pattern is created in connection with the forming of the base layer, or at least one top layer by local redistributions within the layer of at least one substantial part of the solid material in the fibre furnish, whereby the pattern in said layer is created under simultaneous dewatering, and that the local redistributions are dependent of the pattern as well.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims the priority of U.S. Provisional Application No. 60/296,728, filed in the United States on Jun. 11, 2001, and to Swedish Patent Application No. 0102065-0, filed in Sweden on Jun. 11, 2001, the entire contents of which are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Technical Field

[0003] The invention relates to a multi-layer paper web, preferably a single-ply tissue paper web with at least two layers and a method for forming such as well. A base layer of fibre furnish is firstly formed on a wire, whereupon at least one top layer is deposited on top of the base layer, which is supported by a wire during the deposition of the top layer, whereby the base layer and at least one top layer are deposited by a fibre suspension jet, and the hereby deposited base- and top layers are formed by means of twin-wire technology.

[0004] 2. Related Art

[0005] When traditionally manufacturing soft paper, it is often performed by multi-layer forming. Traditional multi-layer forming enables the cost performance relationship of the product to be optimised by using different furnishes in different layers. For many paper products, the multi-layer technology enables an increase of the percentage of recycled paper and the high yield pulps, which is interesting both for cost reducing and environmental reasons.

[0006] Multi-layer forming technology can be grouped into three main categories: (a) forming each layer in a separate forming unit before couching the layers together, (b) simultaneous forming of all the layers in one forming unit, using a multi-layer head box divided into several layers, and (c) forming the web layers on top of each other in a sequential mode, i.e., forming the second layer on top of the first layer, etc. The present invention belongs to this last category.

[0007] Simultaneous forming of the tissue products of each layer in a separate forming unit, before couching the layers together, is shown in WO 95/13424 and in WO 96/35018 as well. However, all variants of separate forming of each layer have one problem in common, namely the layer bonding, which limits the Z-direction strength of the multilayer product. Often starch or some other bonding agent has to be sprayed on the layers before couching them together.

[0008] Simultaneous forming of a multi-layer product can also be employed. Examples of multilayer head boxes are described in EP 0 681 057, and the technology is shown in WO 95/13424, WO 95/35018 as well. However, this method involves several problems. Hitherto, it has proved difficult to accomplish acceptable layer coverage characteristics with simultaneous forming according to this technology, and this method has proven to give lacking layer purity as well. Further, the forming with one head box and one single dewatering unit gives a limitation concerning the possibility to keep a low head box concentration, particularly at high velocities and at higher basis weights for soft paper (single-ply products). A low forming concentration is a condition for a good strength exploitation of the used raw material. Moreover, it is impossible to give the layers different basis weight patterns since all the layers are simultaneously formed.

[0009] Multi-layer forming of the paper in a sequential mode with twin-wire technology, with both two-sided and partially single-sided dewatering, is amongst others described in U.S. Pat. No. 3,821,073. Single-sided dewatering is described in SE 0002998-3 as well. Two-sided dewatering and multi-layer forming of soft paper or tissue paper in a sequential mode is described in WO 99/09249.

[0010] The problem with layer-bonding, which is obtained when each layer is separately formed and then couched together, is avoided by the method according to the invention by means of substantially depositing fibre furnish on top of the preformed layer, whereby a good layer-bonding is obtained. This implies that the Z-direction strength of the multi-layer product is often determined by the Z-direction strength of the individual layers, rather than by the layer bonding.

[0011] In the present day situation, with the present technologies, moreover it is very difficult to manufacture a multi-layer soft paper with conventional technology, in which paper each layer has a pattern being independent of the others layers. Particularly it has not been possible to obtain a pattern in the middle layer or layers, that is not dependent on the pattern of the other layers. It leads to that several plies must be used, which are laminated together in connection with the conversion, e.g. by gluing, embossing or the like, for obtaining the desired product. Moreover, in addition there are several steps at the conversion, such as embossing, which often leads to an undesired impairment of the product.

OBJECTS AND SUMMARY

[0012] New products can be obtained by the method of twin-wire technology according to the invention, in which a pattern with a basis weight distribution is created in at least one of the layers during the forming. The middle layer and the outer layer can be given different characteristics for better matching each other. The middle layer can provide bulk and strength, and the outer layer can provide softness, roughness or strength. Combinations of, e.g., strength and absorption, strength and smoothness, absorption and strength, can be improved and optimised by the method giving the possibility to optionally chose and combine the appearance, the function and the characteristics of the layers. The two-sidedness can also be reduced of the single-ply web or the product. The reduced two-sidedness is especially desirable when at least three layers are used.

[0013] An object of the present invention is to provide a method for forming at least a multilayer soft paper web, comprising at least two layers, at least one layer of which consists of a plurality of different clear, distinct patterns created by the basis weight variations. The layer shows the basis weight variations in a pattern achieved by a patterning wire, which has created local displacements and redistributions of at least one substantial part of the solid material, such as the fibres, the filling medium and the like, within the layer in connection with the forming, during simultaneous single-sided dewatering by means of twin wire technology, and that the local redistributions are dependent on the pattern as well. Thus, the pattern consists of the locally chosen areas in the layer containing more material and the locally chosen areas with a substantially lower percentage of material. This implies that the basis weight of the layers in the locally chosen areas with more material is substantially higher as compared to the locally chosen areas with lower, or practically no content of material having low, none or practically a non-existent basis weight.

[0014] A multi-layer soft paper web, which is preferably a single-ply tissue paper web, which can compete with a multi-ply soft paper product, and having at least two layers, is formed according to the method of the invention. Firstly, a base layer of fibre furnish is formed on a wire or the like in an optional way. Subsequently, at least one top layer is deposited on top of the base layer. This can then be repeated for one or several top layers by repeated application of the method according the invention, whereby an optional number of layers are formed. The total number of layers in the multi-layer product can be anything from two to three layers, to practically as many layers as that may be. The layers are formed on top of each other in a sequential mode in such a way that distinct, clear patterns are created.

[0015] The term base layer refers to the layer on top of which the next top layer is formed. That is, the latest formed layer is always the base layer, on top of which the top layer is formed. Consequently, the top layer refers to the layer being formed on top of a layer already formed. The firstly formed layer is directly formed against the wires, i.e., the layer is not formed on top of a base layer already formed, and thus is neither a top layer. In the soft paper product, the firstly formed base layer may, just as any layer, end up in several different locations in the product, depending on how it is combined with the other layers. Thus, all the layers can end up as a lower layer, an upper layer or a middle layer. A pattern can be created in the firstly formed base layer when the twin wire technology is used by means of local redistributions within the layer, i.e., in the plane, of at least one substantial pan of the solid material in the fibre furnish, whereby the pattern in the base layer is created during simultaneous dewatering and the local redistributions are dependent of the pattern as well. The firstly formed base layer of the fibre furnish can also be formed on a wire or the like in an optional way, with or without patterns.

[0016] At the manufacturing of the tissue-product a base layer is firstly formed, whereupon at least one top layer is formed on top of the base layer by single-sided dewatering during at least one substantial part of the forming zone, in a direction away from the base layer. The base layer can also be formed by single-sided dewatering during at least a substantial part of the forming zone. The firstly formed base layer is supported by the wire or the like during the deposition and the forming of the top layer. The top layer is deposited With a fibre suspension jet, and the hereby deposited base and top layers are formed by means of twin wire technology.

[0017] A pattern is created of at least one top layer in connection with the forming, while the top layer lies on top of any of the previously formed layers. The pattern is created, which is performed by means of local redistributions within the layer, i.e., in the plane, of at least one substantial part of the solid material in the fibre furnish, whereby the pattern in said top layer is formed on top of any of the previously formed layers during simultaneous dewatering. The local redistributions are dependent of the pattern in question. The pattern is preferably created by a patterning wire, forming one of the wires in the twin wire nip, in which the top layer is formed when the furnish is dewatered through the wire. The second wire is constituted of the wire supporting the base layer. In the case when the patterns have been created in the firstly formed base layer, according to the method described above, the other layers can also be formed without patterns.

[0018] By means of the method according to the invention, the possibility is utilized to create a layer on top of another layer, deliberately differing from the previous layer in an independent way. In this way it is possible to achieve products with large variation possibilities, in which both the outer layers, just as one or several of the middle layers, can consist of basically any pattern. This has previously not been possible, and a Tissue product with substantially independent included layers can be manufactured by a method according the invention.

[0019] Yet, another object of the invention particularly relates to layers with discontinuous patterns. The discontinuous pattern is constituted of the solid material, in which chosen local areas with solid material within the layer are well limited from each other, and are not connected to other local areas with solid material. Thus, the local areas with basis weight are separated from other areas with basis weights, and thus are surrounded by the areas with none, or particularly a non-existent basis weight. The local areas separately located, i.e. the so-called discontinuous areas of solid material, can be constituted by locally smaller, or relatively small, delimited areas, just as well as they can be constituted of discontinuous extended areas. The invention also comprises other patterns, which just as the discontinuous patterns described above neither can constitute a self-supporting web.

[0020] An additional object, being included by the invention as well, is to create different reinforcing patterns. So-called discontinuous reinforcing patterns but also continuous reinforcing patterns are included. The patterns, also being interesting for the invention, consist of patterns providing distance layers, which in turn can give rise to different characteristics. By forming different patterns in the layers, the combination of the strength of the internal layer, or the internal layers, and the smoothness and softness of the outer layers, can be improved. Further, according to the invention, other patterns can be created improving the combination or the absorption ability of the internal layer or the internal layers and the stiffness, softness or strength of the outer layers.

[0021] Moreover, clear and distinct, visual patterns are enabled, comprising for instance logotypes, signs, letters and symbols, and patterns being created during the dewatering can be incorporated as one or several internal layers as well. The pattern can consist of geometrical, descriptive or pure fantasy pattern, or be constituted of a trademark or a pattern, which can be associated with the company, or the products of the company. The invention also includes patterns, either being purely decorative or purely functional, and patterns being both decorative and functional as well. The size of the patterns is larger than one opening in the weave pattern in a wire, which normally relates to sizes from 0.1 m and larger. It enables the patterns to reach fibre size, and larger, for e.g. a logotype patterns having a size of 10-100-eds of mm are used.

[0022] Another object of the invention is to obtain a stronger soft paper. This is obtained in several ways, of which one of the most important ways is to manufacture a single-ply soft paper consisting of several layers in the paper machine, and obtain a finished product, without combining this to a multi-ply product by means of a strongly reduced manufacturing process. By immediately achieving a single-ply product with the desired basis weight pattern in the paper manufacturing process, one or several steps at the converting can be excluded. Such steps can for instance be gluing for a multi-ply product and embossing, in the both cases leading to an impairment of the product via e.g. strength reductions. Thus, the converting step normally implies that the strength of the product is reduced many times. Generally, this strength reduction must be compensated in any of the previous steps of the process, for example by using more fibres or stronger fibres. However, the strength in a completed single-ply product, according to the method of the invention, is not reduced since certain converting procedures can be excluded. This means that the strength utilization of the fibre raw material is better in the finished products since the strength is maintained. Moreover, the layers of the single-ply product according to the invention keep together very well. The improved strength utilization being obtained by the single-ply, multi-layer soft paper of the invention can be used in several ways. Fibres with less strength can be used, or it is possible to use a lesser amount of fibres, and yet to obtain the same strength in the product. Alternatively, recycled fibres can be used in a higher extent than previously been possible. Thus, it is possible to obtain a low fibre cost and also be economical with the virgin fibres. It is also possible to obtain a product with lesser basis weight at the same relative strength, or simply to obtain a stronger product. The improved relative strength can also be utilized for increasing the bulk with a maintained strength, favouring the softness and the absorption capacity of the paper.

[0023] Yet, another object of the invention is to be able to manufacture a multi-layered soft paper, which as a finished product is used as a single-ply product, and in which it is possible to create a pattern in one or several layers, independent of the other layers. The pattern of at least one top layer is shaped independent of the pattern in the previous layer. This is solved according to the method being described in claim 1 or 2. To create a soft paper product, in which the patterns are created with twin wire technology on top of a base layer already formed, has a considerable technical and commercial value as well, and enabling an entire row of different products, not previously present on the market.

[0024] One of the objects of the invention, constituting a very important application in a commercial point of view, is to create a single-ply product with at least three layers, whereby at least one of the middle layers is patterned. For achieving a single-ply soft paper product being substantially symmetrical, three or several layers are preferably used.

[0025] Another object of the invention is to create a discontinuous layer in the middle. In this way, a higher bulk is obtained with the same amount of fibres compared to use entirely continuous layers. A high bulk in the middle, without the fibres needing to cover the complete area, gives a better product concerning absorption, and a more positive experience for the customer, for instance due to a higher softness and a better drapability.

[0026] Thus, layers with more continuous, partially discontinuous or completely discontinuous, i.e., not self-supporting patterns can be manufactured. The selection of layers results in a higher strength, reduced stiffening, controlled bending rigidity, increased bulk, higher absorption capacity, higher storing capacity, lower or higher two-sidedness.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In the following, the invention will be further described with reference to the embodiments shown in the accompanying drawings. The dark sections being shown on the respective layer in FIGS. 5-10 represent the areas locally chosen, which above all consist of more material, such as fibres, filling means and the like. Thus, the black represents the main part of the constituents in the paper within the layer.

[0028] FIG. 1 shows forming of a web with two layers, in which twin wire forming in the sense of roll forming is used.

[0029] FIG. 2 shows forming of a web with four layers, in which twin wire forming in the sense of roll forming is used.

[0030] FIG. 3 shows forming of a layer by means of twin wire forming in the sense of hybrid forming, i.e. a certain pre-dewatering occurs before the twin wire nip.

[0031] FIG. 4 shows multi-ply forming on a Fourdrinier wire, in which twin wire forming is used for forming secondary layers with assistance from dewatering units for dewatering directed upwards, placed after secondary head boxes.

[0032] FIG. 5 shows a discontinuous pattern in a middle layer.

[0033] FIG. 6 shows different discontinuous patterns.

[0034] FIG. 7 shows discontinuous patterns with continuously extended fibre areas.

[0035] FIG. 8 shows a so-called discontinuous reinforcing pattern, a so-called trick-track pattern.

[0036] FIG. 9 shows different reinforcing patterns.

[0037] FIG. 10 shows three patterned layers to a tissue paper web.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] According to the embodiment shown in FIG. 1, a top layer of a two layer structure is formed by means of a fibre suspension jet from a head box 1 being introduced into a twin-wire nip created between one tensioned forming wire 2 and another tensioned wire 3, both of which wrap around a forming roll 4. Another preferred embodiment is when a three-ply structure is formed. However, the number of layers is optional, which can be seen in FIG. 2, showing a four-layer structure. The forming of the top layer is performed on top of a base layer or a previous top layer by a redistribution within the layer, i.e., in the plane of substantially all the fibre famish in the layer in question, while a one-sided dewatering is used in connection with this forming. A displacement of at least a substantial part of the solid material in the top layer is performed in such a way that fibres, filling means and other solid components included in the fibre famish are transported and follows the water and is accumulated in the areas in which the water is drained through the wire or the like. In the areas in the layer, in which the drainage is small or insignificant, it will be a corresponding small or insignificant amount of the fibre material and other solid included components in the fibre furnish as well. Hereby, an amount of different layers with different patterns and forms can be achieved, see for example FIGS. 5-10. This technology can in turn give rise to a variety of different products, a few of which the amount of possibilities rising will be described in the following.

[0039] Moreover, a good layer bonding is obtained by the fact that the top layer comes in contact with the previous layer, while the top layer is in the form of a fibre suspension. A good layer-purity and layer formation in the newly deposited layer can be obtained since a fibre famish with a low concentration is dewatered through a new web-free wire or the like. The single-sided dewatering also results in good z-direction strength in each layer since the water is brought in the same direction in each separate layer. In the cases when having two-sided dewatering, a weakness is incorporated in the layer, in which the water has been drained in different directions.

[0040] Yet another advantage is that the possibilities to control the layer bonding are great. It can be desirable to induce delamination in a certain plane in the sheet in a subsequent process step, e.g., the creping. This is favoured by the fact that it is possible to obtain a good z-direction strength for the separate layers, and a good layer bonding between the layers, in which delamination is not desirable, in combination with a weakened layer-bonding between the layers in which lamination is desired, or a weakened z-direction strength in the layers in which delamination is desired. For instance, a discontinuous layer 7 as shown in FIG. 5 has a lower surface area in which the layer bonding can occur. This gives a weakened layer bonding, which can be used for inducing delamination in a subsequent process step.

[0041] An additional advantage of the invention is that the pattern of the separate layers can be chosen independently of each other. Even for a separate top layer the pattern can be chosen independently of the pattern of the other layers. Accordingly, this is possible since the top layer is formed on top of the base layer, or the previous top layer by single-sided dewatered under at least a substantial pan of the forming zone, in a direction away from the base-layer or the previous layer. A wire to the next dewatering unit supports the baseply, and the previously formed fibre web constantly supports the top layer.

[0042] The base-layer can be formed by twin-wire technology, or with other forming technologies, alternatively. Moreover, a pattern can be created in connection with the forming of said base-layer by a redistribution within the layer of at least a substantial part of the solid material in the fibre famish during simultaneous dewatering, whereby local basis weight differences are achieved in the plane. The base-layer and/or the top layers can have patterns, or be without patterns, these patterns can consequently be varied optionally, whereby every layer can be used as an outer layer or a middle layer just as an inner layer.

[0043] The twin-wire technology or the twin-wire forming comprises forming methods, in which the head box jet is directed into a twin-wire nip, so called Gap forming, FIGS. 1-2, hybrid forming, FIG. 3, and also dewatering units with a drainage directed upwards after secondary head boxes on a Fourdrinier wire, FIG. 4, or other similar methods. Thus, with twin-wire technology is here incorporated all the forming methods, in which two wires make a forming zone. For manufacturing soft paper, which requires high machine velocities, methods are preferred wherein the head box is directed put into the twin-wire nip, whereby a closed forming zone is obtained. The roll forming belongs to this category (not-pulsating dewatering pressure), blade forming (pulsating dewatering pressure) and combinations of these both forming methods. Some examples of such methods are a.o. shown in U.S. Pat. No. 3,056,719, EP 0 699 798, EP 0 454 989, WO 95/34713, U.S. Pat. No. 5,282,933, WO 97/47803, U.S. Pat. No. 4,790,909, DT 2 000 661. The preferred embodiment, as shown in FIG. 1, shows a roll forming, wherein a fibre suspension jet is directed into a twin-wire nip formed by two wires going in infinite loops.

[0044] During at least one substantial part of the forming zone, in which the forming is performed over one or several curved surfaces 4, 14, 114, 1114, the dewatering is single-sidedly performed by means of the curved surfaces 4, 14, 114, 114 being impermeable, whereby the dewatering through the inner wire 2, 3, 23, 113 is prevented. Alternatively, single-sided dewatering can be achieved by means of the inner wire 2 being impermeable. A substantial part of the dewatering is performed through the second wire the outer wire 3, 13, 113, 1113, i.e., the permeable or partially permeable wire. This enables, when a base-layer is formed over the curved surface 4, or when a top layer is formed over the curved surface 14 on the base-layer, or over curved surfaces 114, 1114 on the previous top layer, the dewatering is prevented through the layers, and the wire supporting the layer or the layers due to that the wire 2 or the curved surfaces 4, 14, 114, 11 14, over which the wire 2 runs, are impermeable. Thus, single-sidedly dewatered base layer or the top layer is separated from the inner wire 2, 3, 13, 113 over a suction box 6, 16, 116, 1116, and follows the corresponding outer wire 3, 13, 113, 1113, toward the next formation unit, in which a top layer is formed on top of the previous layer. Each dewatering unit should have a good dewatering capacity, particularly when there are high machine velocities.

[0045] Consequently, the invention can be applied in a plurality of different types of fanning sections, see for example FIGS. 1-4, which all however comprise twin-wire technology/twin wire forming. The twin-wire forming is performed in a forming zone between wires or the like, running over stationary and/or rotary machine element. By the fact that the wires are running over machine elements in form of sheets or the similar, which doesn't give a continuous surface, single-sided dewatering can be achieved by using impermeable wires or the like. At twin-wire forming, the instantaneous dewatering pressure is given by the tension of the outer wire, with regard to its radius of curvature. When the wires ran over rotating rolls, a dewatering pressure can be obtained after an increasing phase approaching a constant level (so-called roll forming according to Webster). This is favourable at soft paper manufacturing, for instance with regard to the wire retention and the strength utilization of the raw material used. Alternatively, the dewatering is performed with a varying or pulsating dewatering pressure wherein the wires run over stationary machine elements such as stationary sheets or strips. Apart from the dewatering pressure, which is a.o. induced by the wire tension, the dewatering can also be reinforced in other ways, for instance by the assistance of vacuum.

[0046] Roll forming according to Webster is shown in FIG. 1, in which the fibre suspension jet is introduced into the twin-wire nip at such a velocity that the outer one of the tensioned wires 3 is deflected, while maintaining a substantially constant tension during the deflection of the outer wire 3, by means of the outer wire being supported by a rotating support 5, at least one of which is resiliently or displaceably mounted for compensating for said deflection. Thus, the outer wire 3 is mounted so that it may be deflected. Thus, the radial position of the outer wire under the forming procedure is not given in advance. The radial position along the roll periphery is determined by such factors as the thickness of the fibre furnish jet, the material concentration in the fibre furnish, the drainage resistance of the furnish, the wire tension and possible vacuum in the forming roll. The jet has a sufficient kinetic energy for deflecting the outer wire and penetrating into the nip. The Webster method is described in a.o. U.S. Pat. No. 3,056,719. The forming can also be performed by fixed wire geometry, or fixed suspension, which can be send in U.S. Pat. Nos. 3,543,834 and 3,821,073.

[0047] According to at least one embodiment of the invention, the forming is started and completed over the forming wire 4, 14, 114, 1114. Subsequently, the fibre web structure is substantially fixed to that no significant redistribution of the fibres is performed when the web passes over additional dewatering elements. Then an additional strengthening of the web can be performed according to well-known methods such as couch rolls, suctions boxes and the like, before the web comes into the press section or the drying section or other subsequent units or sections.

[0048] The forming of each top layer is performed on a separately chosen and adjusted wire 3, 13, 113, 1113 or the like, in order to be able to create a pattern in the layer. Hence, every layer receives a completely adjusted wire, and a patterned fibre web is received by means of the wire of tile like. Moreover, it is easy to change the pattern by means of exchanging wires.

[0049] The pattern may have purely esthetical qualities, or the purpose with the pattern can be to affect different physical material characteristics of the finished soft paper, which will be further described under the closer description of the preferred embodiments shown in FIGS. 5-10. Examples of characteristics of the soft paper web or the products as the invention will be able to effect, are bulk, stiffness, strength characteristics, elongation, absorption characteristics, partly of water and partly of highly viscous fluids, and anisotropy as well.

[0050] The forming wire or the like 3, 13, 113, 1113, for forming at least one of the top layers, has a pattern. The areas with impaired dewatering force the solid material in the fibre famish, particularly the filling means and the fibres, to be displaced to the open areas, and thereby distinct patterns are created, consisting of different local areas with different basis weights. The displacement or the redistribution of the solid material in the fibre furnish, which is performed under the forming of the top layer on top of the previous layer, is performed by dewatering through the wire or through mechanical pressure against the wire, or by exposing the wire in another way, making the fibres redistributed according to the desired pattern in the local areas, so that the fibres are dispersed and accumulated. Openings in the top layer are created in such a way that the desired pattern is obtained.

[0051] In connection with the forming and the deposition of the fibre furnish, a particular patterning process takes place by this method. At the forming/the patterning, the local areas of the wire with a higher dewatering capacity will provide the formed layer areas having a higher basis weights, while areas of the wire with lower dewatering capacity will provide areas with a low, lower, none or practically non-existent basis weight of the fibre web. The deformation or the blockages of the wire or the like can particularly preferably be performed so it gives the pattern creating surfaces, the local areas, in which the pattern creates a distribution pattern being considerably independent of the pattern of the wire web. This gives a wire with the best possible capacity to create a visual distinct pattern on the fibre-layer.

[0052] Patterning wires can be used for providing a pattern to a paper web or another fibre web in connection with wet forming. This is achieved by shaping the patterning wire so that the dewatering of the actual fibre suspension through the wire is interfered or controlled in such a way that local basis weights or fibre length variations a-rise in the fibre web. The forming of a layer is performed by means of using a particular patterning wire or the like, whereby the wire or the like is provided with means, for instance such as blockages, restricting the drainage of the fluid through the wire in a given pattern.

[0053] The patterning wire can be achieved by blocking continuous, discontinuous or partially discontinuous areas of a conventional open wire by means of a cured polymer, whereby the wire can be of any material, for example plastic or rubber. The blocked areas can be achieved by supplying other materials such as thermoplastic, thermosetting plastic, solder metal by electrolytic depositing, or by applying a sealing compound. A decorative material can be placed on top of a conventional wire for creating a composite material. A composed non-woven wire can be blocked, for example by smooth finishing. These wires also obtain blocked drainage openings, which can cause patterns.

[0054] Similar patterning effect can also be obtained by incorporating a pattern in the wire at the weaving of the wire, for example in a weaving loom of Jacquard type. It can also be conventional weaving patterns with a number of shafts.

[0055] A number of different wire types can constitute the base for the described patterning wires, for instance single-, twin- or triple mounted wires. The wire can be replaced by woven fabric or material, which can be used in a similar way, for example such as film, screen, woven fabric, felt, membrane, moulded membranes, non-woven, foil or bands. They can have an etched, cut, stamped, burned out or a moulded pattern. Concerning bands and the like, it is possible to either put a pattern on the band, or use a band with a finished pattern. All the conventional wires, bands or the like are included in the invention and can be used according to the method of the invention.

[0056] Further, the invention relates to use a wire with a plurality of threads arranged in a wire structures having a plurality of drainage openings and a patterning area substantially in the plane of the wire, intended for the forming, a number of the threads of which show a permanent deformation, forming one or several pattern creating surfaces within the patterning area at the forming. Moreover, a number of the drainage openings can be blocked at least as a consequence of the deformation, thereby the openings or the areas can be blocked to a different degree, which can give one or several continuous transitions, from a non-blocked dewatering opening to completely or partially blocked dewatering openings. This method is closer described in the Swedish patent application SE 9903849-9.

[0057] With the concept soft paper web and product, particularly a single-ply multi-layered tissue, the embodiments of the invention include several different paper webs and products of soft paper. It can be paper, for example for personal use, and use in the household, such as toilet paper, kitchen paper, paper towels, house hold paper, facial tissue, cosmetic papers, handkerchiefs, napkins, dinner napkins, wet wipes, wipes for infants, flannels, table cloths and swabs. Further, other types of paper axe included, particularly for commercial and industrial use such as for example cloths, swabs and tissues for cleaning, polishing, oil wiping and waste cloths for industrial cleaning and the like, for example for use at workshops or printing shops. It can also both be dry and wet towels, cloths and prepared tissue. The paper can be prepared at the production or after treated with for example liquids, suspensions, solutions, lotions, various chemicals, means, therapeutic means or the like. Further, paper for other uses are included, it may be tablecloths, cloths, strengthened tissue and non-woven-material. Other soft paper products, which can be included therein, be close to, or being close related with the said products, are also within the definition of a multi-layer soft paper product, particularly a multi-layered tissue product according to the invention. Moreover, a multi-layered soft paper product may also be converted to be part in other sanitary articles, such as nappies, sanitary napkins, panty liners and incontinence guards.

[0058] It can be anticipated that paper pulp of all the different variants, which is normally embodied at soft paper manufacturing, can be used in this invention. Other pulps of cellulose fibres can also be used. Some examples are the seed hair of cotton linters, bast cells such as ramie, linen and jute, straw pulp, bamboo pulp, bagasse, hemp or nylon. Chemical wood pulp being used a.o. can be sulphite pulp, sulphate pup and organosol pulp. Mechanical wood pulp being used can be ground pulp, thermo-mechanical pulp, refiner mass and chemi-mechanical pulp as well. The pulp can be made of fibres of coniferous wood such as broad-lead wood. Another important raw material is recycled fibres from outgrowth and waste paper. Moreover, synthetic- and half synthetic fibres can be used.

[0059] It is also anticipated that the fibre pulp, before becoming a fibre furnish, can be treated according all the normal or known treatment methods being available. It may be that the fibre or the pulp is grinded, filtered, cleaned in different ways, bleached, treated in a chemical and/or mechanical way, and other procedures included in the normal pulp handling and/or the preparing.

[0060] The finished fibre furnish can also contain process chemicals, for example such as retention means, or functional chemicals for giving particular characteristics to the finished product. For example, it may be retention means, flocculating means, filling means, different strength giving or starching means, softening agents, pH giving or pH controlling means, hydrophobic means, absorptions means, stabilizers, whiteners and so on, The usable means according to the invention are not limited to the means mentioned above: but also comprise other known or available process- or functional chemicals. Moreover, the fibre furnish can be water based and other liquids can partially or mainly be a part thereof.

[0061] Different types of figurative or non-figurative patterns can be arranged in any of the layers of the soft paper as a basis weight pattern with one or several openings and one or several fibre accumulations, figurating the desired pattern. The feature of the desired pattern, above all differing from other conventional basis weight patterns—manufactured with other methods—is that the lower basis weight areas have a very low basis weight, practically a non-existent or none basis weight at all, creating opening or holes in the actual layers. The holes or the openings in one or several internal plies can be surrounded and enclosed by the outer layers. A pattern being manufactured according to the method occasionally reminds of a watermark—, see for instance 12, 14 in FIGS. 6 and 7.

[0062] Discontinuous patterns are shown in the preferred embodiments according to FIGS. 5-7 and are patterns of basis weights, in which the solid material in the fibre furnish, particularly the fibres and the filling means, have been accumulated in areas being completely separated from each other. Thus, it is the areas in the layer, consisting of the fibres that constitute the discontinuous pattern. Hence, the layer with the discontinuous pattern is not self-supporting and is very difficult or even impossible to manufacture with conventional methods, but this is now possible with the method according to the invention.

[0063] It is naturally also possible to permit the pattern creating areas in for instance in FIGS. 6 and 7 to be constituted of empty sections, or sections with lesser basis weight than the surrounding sections.

[0064] A layer with a discontinuous pattern 7 can be used as one or several middle layers, which is shown in FIG. 5. The discontinuous pattern creates distance or bulk between the outer layers, and then it is possible to talk about distance layers. A discontinuous or non-uniformly shaped intermediate distance layer can create a bulk, giving a higher absorption- and storing capacity. Moreover, this “bulk feeling” gives a higher positive experience to the consumer. Amongst others, highly viscous liquids can be stored in a very preferred way, but this is also valid for other liquids. In the cases in which the middle layer gives a non-uniform layer, instead of a layer of uniform thickness giving extra bulk, this is compensated with strength in the outer layers. The discontinuous pattern 7 can be optionally chosen. Other appropriate embodiments of the discontinuous patterns 9, 11, 13, 15, 17, 21, 23 are shown in FIGS. 6-7 and 9. The discontinuous areas of the solid material 8, 10, 12, 18 are constituted of smaller areas, and relatively small restricted areas, with regard to the surface. The described embodiments in FIGS. 7 and 9 show discontinuous patterns 13, 15, 21, 23, constituting continuous extended areas of the solid material 14, 16, 22, 24. Thus, the areas constituting the discontinuous pattern can in turn be constituted of discontinuous patterns or continuous patterns.

[0065] A pattern in the middle of a product, which is not self-supporting as well, gives possibilities to completely new patterns, which except for the pure design can also combine both design and characteristics serving its functional purposes very well, but nevertheless can entirely be created as patterns for giving the products a certain function or characteristic. Patterns in the middle layer are protected by the outer layers, which can be continuous, or possibly also partially discontinuous. One of the most important applications comprises a one-ply product with at least three layers, of which one middle layer with a pattern can also be discontinuous, see FIG. 5. The firstly formed layer, i.e., the base layer, can constitute the patterned layer, just as the top layer formed later on.

[0066] In the cases, in which strengthened patterns are requested, it is also possible to create so-called discontinuous reinforcing patterns, see FIG. 8, for example such as so called tricktrack patterns 17. In the locations, in which the fibre lines being intended to constitute a reinforcing pattern, normally would have crossed each other, interruptions have been made in this pattern, whereby openings have been created. This is especially advantageous since reinforcements also imply stiffenings. By not having a continuous reinforcing pattern, but instead using a so-called reinforcement pattern leaving openings wherein the fibre pattern should normally have been crossed, the stiffening effect can be reduced. None of the fibres bridges over each other, and the openings are sufficient for breaking the stiffening. Also different continuous reinforcing patterns can naturally be used in the product, see FIG. 9.

[0067] Other examples of reinforcing patterns, which can be created in one or several layers, are reinforcements with patterns in the machine direction, 15, 21 of FIG. 9. The bending rigidity or elasticity normally differs in the longitudinal and the transverse direction of the machine, which not entirely, but perhaps above all originating from the following creping, which further decreases the bending resistance, the bending rigidity in the machine direction. Originating from this fact, bending rigidity can be created in the machine direction by means of strong basis weight patterns 16, 22 in the longitudinal direction 15, 21 of the machine, giving an alternating strong and weak-basis weight pattern in the transverse direction. By creating a higher bending rigidity in the machine direction in such a way, said bending rigidity is reduced in the creping step later on, a more uniform product can be obtained with regard to the bending rigidity or elasticity in the longitudinal- and the transverse direction. A reinforcing pattern can also be made so the layer is strengthened in the transverse direction 21 of the machine. This as well as similar patterns can be used when it is desirable to strengthen the creping-effect. As the middle layer obtains reinforcing characteristics, the outer layers are mainly designed for the softness.

[0068] According to the invention, the layers can be created and combined in different ways, and a single-ply product can be composed in an optional way. A preferred example of such a product, FIG. 10, is a three-layered soft paper with an outer layer, which is formed with large openings 31, facilitating for highly viscous liquids or oils to penetrate the material. The middle layer is formed to a bulk-giving layer, for instance a discontinuous intermediate layer 32 with fibre accumulations of the solid material 33, absorbing and storing the highly viscous material in the middle. The second outer layer consists of a plane or rough surface, giving a good absorption for, e.g., water or other low viscous liquids. In this way, a two-sidedness has been obtained, which can normally have been created in other ways as well, and with other functions, completely according to the desires or the demands of the producer or the consumers.

[0069] Colourings in certain layers in combination with the basis weight. patterns can create distinct and clear patterns in the product. At least one top layer can be coloured in another way than the other layers. An example is that the fibre famish being- used to the discontinuous optional pattern in an inner layer is coloured, while the outer layers have another colour. This can be especially striking when figures, trademarks or other aesthetical or functional patterns are used. Examples of discontinuous and continuous patterns, see FIGS. 5-10.

[0070] Naturally, it is also possible to use different fibre furnishes in different layers. The Yankee side gives a more smooth side than the cap side, while many important products in a volume point of view, such as toilet paper and household paper, should be substantially symmetrical. The two-sidedness, which is provided by the Yankee-cylinder, is possible to prevent by choosing the fibres in the layers so it is possible to alternate the smoothness of the sides. That is, it is possible to choose fibres, and perhaps also the forming of the layer so the side, becoming the cap side, is initially softer. With the softening effect of the Yankee-cylinder, the smoothness will be balanced by means of the process.

[0071] For manufacturing a substantially symmetrical soft paper in the higher quality segments, one of the preferred single,-ply products consists of at least three layers in combination with a drying procedure, resulting in a lower degree of the two-sidedness than the Yankee-drying. Thus, is it favourable if the drying, at least partly, is performed as through-air-drying (TAD), which can give a low degree of the two-sidedness. For example, it is then also possible to use short fibre furnish in the outer layers for smoothness, and long fibre furnish in the inner layers for strength and bulk.

[0072] It is difficult, almost impossible, to describe all the variants of products, which can be created with the method according to the invention. Hence, all the possible variations and variants of the described products are considered to be included in the invention according to the method, and the products being described according to the claims and being closer described in the description. The invention is not limited to the shown embodiments since these are, entirely intended to explain the invention. Within the scope of the invention it is also possible to combine characteristics from different embodiments with each other.

Claims

1. A method for forming a single-ply, multi-layered paper web, in which a base-layer of a fibre furnish is firstly formed on a wire, whereupon at least one top layer is deposited on top of the base-layer, which is supported by a wire under the deposition of the top layer, whereby the base-layer and at least one of the top layers are deposited with a fibre suspension jet, and the hereby deposited base and top layers are formed by twin wire technology, wherein a pattern is created in connection with the forming of the base layer and/or at least one of the top layers is created by local redistributions within the respective layer of at least one substantial part of the solid material in the fibre famish, whereby the pattern in said base layer, and/or at least one of the top layers is created under simultaneous dewatering, and that the local redistributions are dependent on the pattern as well.

2. A method for forming a multi-layer paper web, in which a base-layer of fibre furnish is firstly formed on a wire, whereupon at least one top layer is deposited on top of the base-layer, which is supported by a wire or the like under the deposition of the top layer, whereby the top layer is deposited with a fibre suspension jet, and the hereby deposited top layer is formed by twin wire technology, wherein a pattern is created in connection with the forming of at least one of the top layers by local redistributions within the layer of at least one substantial part of the solid material in the fibre famish, whereby the pattern in said top layer is formed on top of any of the previously formed layers under simultaneous dewatering, and that the local redistributions are dependent on the pattern as well.

3. The method as claimed in claim 1, wherein the twin wire nip comprises a patterning wire, through which the dewatering takes place, creating the desired local redistributions of the solid material in the layer.

4. The method as claimed in claim 2, wherein the forming of said base layer is performed by twin wire technology.

5. The method as claimed in claim 2, wherein a pattern is created in connection with the forming of the base layer by local redistributions within the layer of at least one substantial part of the solid material in the fibre furnish, whereby the pattern in said base layer, and/or at least one of the top layers is created under simultaneous dewatering, and that the local redistributions are dependent of the pattern.

6. The method as claimed in claim 1, wherein the pattern of at least one top layer is formed independent of the pattern in the base layer or any other top layers.

7. The method as claimed in claim 1, wherein a base layer is firstly formed at the manufacturing of the paper web, whereby a top layer is formed on top of the base layer, whereby the forming, forming at least one patterned layer, is performed by single-sided dewatering under at least one substantial part of the forming zone, with direction away from the base layer.

8. The method as claimed in claim 1, wherein the forming and the dewatering of at least said layers are performed in a forming space between the wires or the like, running over one or several curved surfaces.

9. The method as claimed in claim 1, wherein singled-sided dewatering of at least said patterned layer is performed by means of the forming surface is impermeable.

10. The method as claimed in claim 1, wherein the forming of at least one layer is performed by using a particular patterning wire or the like, whereby the wire is provided with means restricting the drainage of the fluid in a given pattern through the wire.

11. The method as claimed in claim 1, wherein the fibre furnish, being used in at least one top layer differs in its constitution from the fibre furnish being used in another layer, regarding the type of fibres or the chemical additive.

12. A multi-layered soft paper web, wherein it is manufactured according to the method in claim 1.

13. A multi-layered paper web, wherein at least one of the layers shows basis weight variations in a pattern provided by a patterning wire, which has created local displacements and redistributions of at least one substantial part of the solid material within the layer in connection with the forming.

14. The multi-layered paper web as claimed in claim 13, wherein at least one top layer is coloured in a different way than the other layers.

15. The multi-layered paper web as claimed in claim 13, wherein at least one of the layers consists of a discontinuous layer, which is defined by the areas in the layer having an substantially higher basis weight compared to the surrounding areas having none, or almost an non-existent basis weight, wherein the solid material is constituted by a discontinuous, non-self-supporting web in the layer.

16. The multi-layered paper web as claimed in claim 15, wherein the non-self-supporting layer comprises continuous extended bands or stripes consisting of the solid material in the layer.

17. The multi-layered paper web as claimed in claim 15, wherein the non-self-supporting layer comprises discontinuous areas consisting of the solid material in the layer.

18. The multi-layered paper web as claimed in claim 13, wherein at least one of the layers contains a reinforcing pattern, substantially the complete solid material of which constitutes the reinforcing pattern in the layer, which increases the strength of the paper web in the longitudinal- or the transverse direction.

19. The multi-layered paper web as claimed in to claim 18, wherein at least one layer is formed to a pattern, which gives reinforcements in the machine direction, giving a higher rigid stability in the machine direction.

20. The multi-layered paper web as claimed in claim 13, wherein at least one top layer is formed to a discontinuous reinforcements pattern.

21. The multi-layered paper web as claimed in claim 13, wherein at least one top layer is formed to a patterned intermediate bulk-giving distance layer.

22. The multi-layered paper product as claimed in claim 13, wherein at least one layer comprises a basis weight pattern in form of a watermark-constituting a logotype, a descriptive or representative pattern, sign, symbols or the like.

23. A single-ply, multi-layered soft paper web as claimed in claim 22, wherein the paper has at least three layers, two outer and at least one middle layer of which, whereby at least one middle layer consists of said patterned, discontinuous or bulk-giving layer.

24. A single-ply, multi-layered soft paper web as claimed in claim 13, wherein the paper has at least three layers, two outer layers and at least one middle layer, whereby at least one outer layer has openings, which promote absorption of highly viscous liquids, at least one middle layer consist of a bulk-giving layer, which absorbs and stores liquid, and that at least one second outer layer has a smooth or rough surface.

25. The method as claimed in claim 1, wherein the web is a tissue paper web with at least two layers.

26. The method as claimed in claim 2, wherein the web is a tissue paper web with at least two layers.

27. The method as claimed in claim 3, wherein the solid material includes fibres or filling material.

28. The method as claimed in claim 10, wherein the means includes blockages.

29. The multi-layered soft paper web as claimed in claim 12, wherein the web is a tissue paper web with at least two layers.

30. The multi-layered paper web of claim 13, wherein the web is a tissue paper web with at least two layers.

31. The multi-layered paper web as claimed in claim 13, wherein the solid material includes fibres and filling means.

32. The multi-layered paper web as claimed in claim 15, wherein the solid material includes fibres or filling material.

32. The multi-layered paper web as claimed in claim 16, wherein the solid material includes fibres and filling means.

33. The multi-layered paper web as claimed in claim 17, wherein the solid material includes fibres and filling means.

34. The multi-layered paper web as claimed in claim 18, wherein the solid material includes fibres and filling means.