PAPER MACHINE CLOTHING AND METHOD FOR THE PRODUCTION THEREOF

Abstract

The invention relates to paper machine clothing, in particular a press felt for a paper, cardboard or tissue machine, comprising a load absorbing base structure that extends in longitudinal and cross direction of the clothing and which comprises, and in particular is formed by: a) a longitudinal reinforcement module substantially providing the dimensional stability in longitudinal direction of the clothing, and b) a transverse reinforcement module substantially providing the dimensional stability in cross direction of the clothing, whereby the transverse reinforcement module and the longitudinal reinforcement module are arranged one on top of the other and are interconnected with each other. The invention is characterized in that the transverse reinforcement module is a warp knit fabric which is composed of at least one system of weft threads arranged parallel to each other, and at least one system of stitch forming sewing threads which extends substantially perpendicular thereto into which the weft threads are integrated to form a textile fabric, wherein the weft threads extend diagonally to the longitudinal direction of the clothing and have a greater flexural strength than the sewing threads.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation of PCT application No. PCT/EP2009/064833, entitled “PAPER MACHINE COVERING AND METHOD FOR THE PRODUCTION THEREOF”, filed Nov. 9, 2009, which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to paper machine clothing, especially a press felt for a paper-, cardboard- or tissue machine, comprising a load absorbing base structure which extends in longitudinal and cross direction of the clothing and which comprises, in particular which is composed of a) a longitudinal reinforcement module substantially providing the dimensional stability of the clothing in longitudinal direction, and b) a transverse reinforcement module substantially providing the dimensional stability of the clothing in cross direction of the clothing, whereby the transverse reinforcement module and the longitudinal reinforcement module are arranged one on top of the other. Further, the invention relates to a method to produce a clothing, especially a press felt for a paper machine which has a length and a width, comprising the following steps: a) provision of a longitudinal reinforcement module with a width and a length which is consistent with the width and length of the clothing which is to be produced, b) provision of a transverse reinforcement module with a width and a length which is consistent with the width and length of the clothing which is to be produced, c) locating the longitudinal reinforcement module and the transverse reinforcement module on top of each other and d) connecting the transverse reinforcement module with the longitudinal reinforcement module.

2. Description of the Related Art

Paper machine clothing, especially press felts for paper-, cardboard- or tissue machines normally include a basic structure which provides the dimensional stability of the felt, and which is furnished with one or more fibrous nonwoven layers.

In the past the objective in the development of new press felts was oftentimes to replace the felt belts through a modular composition of individual components and to thereby replace woven structures, since woven structures can only be produced with low productivity.

WO89/03300 for example shows press felts composed of modules. Here, modules are suggested which are composed of a laid structure of longitudinal threads which is bonded with one fibrous nonwoven layer, as well as modules which consist of a laid structure of cross threads which is bonded with one fibrous nonwoven layer.

In order to simplify the production of modular press felts of this type it is further suggested in EP 1837440A1 to produce the tensile load absorbing longitudinal reinforcement module from a laid structure of longitudinal threads which is bonded with a fibrous nonwoven layer in one winding process; and to construct the transverse-reinforcement module which is used to increase the transverse stability from several transverse-reinforcement module segments which extend only along part of the length of the press felt and which are produced in a first manufacturing step, also through a winding process like the longitudinal reinforcement module and which, in a subsequent manufacturing step are trimmed to the width of the press felt that is to be produced, and are oriented with their threads transversely to the laid structure of longitudinal threads, and arranged after one another in longitudinal direction of the felt. A disadvantage of these transverse reinforcement structures is hereby that they are produced from a laid structure of longitudinal threads which is ready-made to be used as transverse reinforcement module and must be trimmed and consist of a plurality of individual segments arranged after one another in longitudinal direction of the press felt.

The known modular press felt concepts consist of laid structures of longitudinal threads and of laid structures of cross threads, whereby the two laid structures are bonded with each other through only one fibrous nonwoven layer. A disadvantage of these structures is that such laid structures often only provide a very limited internal volume in the press felt. Also, since the laid structures of longitudinal and cross threads can move against each other they move aside for each other when running through the press nip, which can lead to a further reduction of the internal hollow space volume and consequently to a reduction in the water absorption capacity.

In press felts with base structures which are woven from monofilaments there is often the problem of poor anchoring with the base structure, since the fibers can often only be anchored poorly to the base structure consisting of the smooth monofilaments during needle bonding.

Moreover woven base structures are often much thicker than laid thread structures because of thread crimping at the thread crossover points.

The objective of the current invention is to suggest, and what is needed in the art is, press felts in which the aforementioned disadvantages no longer occur and which, in addition are cheaper to produce than the press felts which are known from the current state of the art.

SUMMARY OF THE INVENTION

The objective is solved by, and the present invention provides, a paper machine clothing, in particular a press felt for a paper, cardboard or tissue machine, comprising a load absorbing base structure that extends in longitudinal and cross direction of the clothing and which is formed from a longitudinal reinforcement module substantially providing the dimensional stability in longitudinal direction of the clothing, and a transverse reinforcement module at least partially providing the dimensional stability in cross direction of the clothing, whereby the transverse reinforcement module and the longitudinal reinforcement module are arranged one on top of the other and are interconnected with each other.

The invention is characterized in that the transverse reinforcement module is a warp knit fabric which is composed of at least one system of weft threads arranged parallel to each other in their longitudinal orientation, and at least one system which extends substantially perpendicular thereto, which is composed of sewing threads that form stitches and into which the weft threads are integrated to form a textile fabric, wherein the weft threads in their longitudinal orientation extends diagonally, especially transversely to the longitudinal direction of the clothing and have a greater flexural strength than the sewing threads.

According to the invention the longitudinal reinforcement module and the transverse reinforcement module are hereby produced independently of each other. According to the invention, the dimensional stability of the clothing in its longitudinal direction is substantially provided by the longitudinal reinforcement module. Moreover, the dimensional stability of the clothing in its transverse or width direction is provided at least partially by the transverse reinforcement module.

The term “the dimensional stability of the clothing in longitudinal direction of the clothing is essentially provided by the longitudinal reinforcement module” is to be understood that more than 50% of the longitudinal stability of the clothing is provided by the longitudinal reinforcement module. In addition it must be stated that the longitudinal reinforcement module can contribute also partially to providing the dimensional stability of the clothing in transverse or width direction of the clothing.

The term “the dimensional stability of the clothing in transverse or width direction of the clothing is provided at least partially by the transverse reinforcement module” is to be understood that at least a part of the transverse stability of the clothing is provided by the transverse reinforcement module.

A textile fabric is to be understood to be a self-supporting textile structure which is flat, meaning that its length and width are considerably greater than its height. It is conceivable in this context that the width and length are greater than the factor 100, especially greater than factor 1000 than the height.

The inventive modular paper machine clothing comprises a transverse reinforcement module, providing the transverse stiffness of the clothing at least partially. The transverse reinforcement module is composed of at least one warp knit fabric which in turn is composed of at least one weft thread system, as well as of least one stitch forming sewing thread system. Herein the warp knit fabric is arranged so that the weft threads extend diagonally, especially transversely to the longitudinal direction of the clothing. The transverse stiffness of the transverse reinforcement module is provided substantially or respectively almost completely by the weft threads. In contrast, the stitch forming sewing threads essentially only serve to hold the weft threads in position during manufacture of the clothing. The warp knit fabric can hereby be produced cost effectively in the knitting process as a flat one-piece warp knit fabric with any desired longitudinal extension in direction of the sewing threads and can subsequently, for example be length-adjusted to the length of the paper machine clothing which is to be produced.

The warp knit fabric can therefore be produced in its longitudinal direction—which is determined by the orientation of the sewing threads—in any desired length. Since the inventive warp knit fabric can be produced in almost any desired length in direction of its sewing threads, and the dimensionally stable weft threads extend perpendicular to the sewing threads, a textile structure is provided by the invention which—in contrast to the solution known from EP1837440A1—does not need to be turned by 90° relative to its longitudinal direction.

Use of a nonwoven material for the transverse reinforcement module in order to hold a laid thread structure in position, as known from EP1837440A1 can be eliminated due to the inventive solution.

Moreover, an expensive weaving process to produce a transverse reinforcement is no longer necessary due to the inventive solution.

Since moreover the weft threads are integrated into the stitch-forming sewing threads in the inventive transverse reinforcement module, the distance between adjacent sewing threads can also be selected to be relatively great, without negatively influencing the integration between the weft threads and the sewing threads. Since in a woven structure the threads are not meshed with each other, but are only connected with each other through thread crimping, the warp threads and weft threads must be arranged relatively close to each other in said structure, so that the connection between them is not too unstable.

The transverse reinforcement module can be located on top the longitudinal reinforcement module, as well as underneath the longitudinal reinforcement module, if the machine side is considered the bottom side and the paper side is considered the top side of the paper machine clothing.

The transverse reinforcement module preferably substantially provides the dimensional stability of the clothing in its transverse direction. The term “that the dimensional stability of the clothing in cross direction of the clothing is essentially provided by the transverse reinforcement module” is to be understood that more than 50% of the transverse stability of the clothing is provided by the transverse reinforcement module. In this context it is conceivable that for example 70% and more, or 85% and more of the transverse stability of the clothing is provided by the transverse reinforcement module.

The longitudinal reinforcement module is preferably produced as an endless belt.

In order to design the inventive base structure even more simple and cost effective, an especially preferred embodiment of the invention provides that the longitudinal reinforcement module includes a laid structure of longitudinal threads or that it is formed by a laid structure of longitudinal threads. In this case it is especially advantageous if the laid structure of longitudinal threads is formed by at least one longitudinal thread extending essentially in longitudinal direction of the clothing and wound continuously spirally in cross direction of the clothing. The at least one longitudinal thread is hereby wound preferably on the width of the base structure.

As a rule, if the longitudinal reinforcement module comprises a laid structure of threads the dimensional stability of the clothing in longitudinal direction of the clothing is substantially provided by the longitudinal reinforcement module. Moreover in this case, the dimensional stability of the clothing in transverse or width direction of the clothing is substantially provided by the transverse reinforcement module.

If the laid thread structure is formed by only one single longitudinal thread, then said thread extends essentially in the provided longitudinal direction of the felt belt and can be wound continuously spirally in the direction of the provided width of the felt belt until provided width of the felt belt is reached. By the spiral winding of the longitudinal thread, a laid longitudinal thread structure can be formed wherein each winding of the longitudinal thread extends parallel to the preceding and following winding of the longitudinal thread.

If the laid structure of longitudinal threads is formed by several longitudinal threads, that is by a group of longitudinal threads, then the individual longitudinal threads extend essentially in the provided longitudinal direction of the felt belt and are arranged side by side in the provided cross direction of the felt belt. The arrangement of the longitudinal threads in the direction of the provided width of the felt belt can herby be wound spirally continuously until the provided width of the felt belt is reached. Through the spiral winding of the longitudinal thread arrangement, a laid longitudinal thread structure can be formed wherein all longitudinal threads of the arrangement always progress parallel to each other and wherein each winding of each longitudinal thread extends parallel to the preceding and the following winding of this longitudinal thread.

The term “that the longitudinal thread or threads extends/extend essentially in longitudinal direction of the belt” is to be understood according to the current invention that the longitudinal thread(s) of the laid longitudinal thread structure and the longitudinal direction of the felt belt together form an angle of 10° maximum, especially 5° maximum.

An additional embodiment of the invention provides that the longitudinal reinforcement module is formed by a woven fabric and/or a knit fabric and/or a spiral screen and/or a knitted fabric. In this case it is for example conceivable that the dimensional stability of the clothing in longitudinal direction of the clothing is essentially provided by the longitudinal reinforcement module. In addition it is conceivable in this case that the dimensional stability of the clothing in transverse or width direction of the clothing is partially provided respectively by the transverse reinforcement module and by the longitudinal reinforcement module. In this case, for example 50% or more of the dimensional stability of the clothing in its transverse or width direction is provided by the longitudinal reinforcement module and accordingly less than 50% is provided by the transverse reinforcement module.

An expansion of the invention provides in addition that the at least one warp knit fabric is formed from one single system of weft threads arranged parallel to each other, and from one single system of stitch-forming sewing threads. This further simplifies the design of the transverse reinforcement module.

The at least one warp knit fabric is produced especially by stitch bonding processes, wherein the weft threads are delivered during stitch formation by means of weft insertion, especially parallel weft insertion. During parallel weft insertion the weft threads are fed parallel to each other and are secured by the stitches. During weft insertion the relative speed between the transport speed of the weft thread application device and the transport speed of the transport chain is compensated such that the weft threads are laid parallel to each other.

In addition, the sewing threads form rows of stitches which are in particular arranged parallel to each other and extend perpendicular to the weft threads, whereby the weft threads are integrated into the stitches. The rows of stitches extend in longitudinal direction of the warp knit fabric. The individual rows of stitches are hereby not particularly intermeshed, but are only connected with each other through the weft threads. The rows of stitches extend hereby preferably in longitudinal direction of the clothing.

An additional embodiment of the invention further provides that each sewing thread forms its own row of stitches, whereby especially each weft thread is integrated into one stitch of each row of stitches.

Especially the length of the stitches extending especially in longitudinal direction is continuously adjustable within a large range, preferably in a range of approximately 0.5 mm and 5.0 mm. Since the weft threads are integrated into the stitches of the sewing threads, the distance of adjacent weft threads can be varied within a large range according to the required or respectively desired properties of the transverse reinforcement module and/or the required production capacity during production of the transverse reinforcement module, without greatly varying the hold of the weft threads by means of the sewing threads. A preferred embodiment of the invention therefore provides that the distance of the weft threads to each other is determined by the length of the stitches in the rows of stitches.

The distance between adjacent weft threads during the production of the inventive warp knit fabric is preferably variable to the extent that, depending on the required properties said warp knit fabric can have a weft thread density in the range of approximately 40 to 200 threads/10 cm, preferably 80-150 threads/10 cm.

In addition it is conceivable that the sewing threads are thinner than the weft threads.

In order to provide a high internal hollow space volume it can be advantageous for example if the weft threads are formed by multifilament yarns.

The multifilament yarns can, for example be formed by twisted monofilament threads. In this context it is conceivable that the monofilaments forming the twisted threads are produced from polyamide (PA). 4-ply threads or 10-ply threads as well as all intermediate levels are hereby conceivable.

Moreover it is conceivable to provide the weft threads in the form of staple fiber threads.

The weft threads can also be in the form of monofilament threads. Here it is conceivable that the weft threads have a round or square cross section. In the first instance it is conceivable that the weft threads have a circular or oval cross section. In the second instance the weft threads can have a trapezoid or rectangular cross section.

In the currently known seamable press felts with woven base structure the longitudinal threads form seam loops. In order to permit insertion of a pintle through the seam loops, the longitudinal threads are in the form of monofilaments. Furthermore, the transverse threads in these types of woven base structures are also in the form of monofilaments, making anchoring through needling of the nonwoven layers on the base structure oftentimes difficult.

Through the provision of the inventive transverse reinforcement module in which the weft threads are formed by multifilament yarns, anchoring of the fibrous nonwoven layers on the base structure through needling can be clearly improved, since the fibers in the fibrous nonwoven layer(s) interlock in the multifilament yarns during the needling process. In addition to the aforementioned multifilament yarns, the weft threads may also include multi-component yarns. Hereby a component which has a lower melting temperature than the other component(s) is conceivable. As a component having a low melting temperature it is for example conceivable to use a thermoplastic material, such as PA, PP or PU which is melted during a thermal treatment, thus effecting an improved anchoring of the fibers of the fibrous nonwoven structure into the base structure.

It is conceivable for example to use PU/PET-bi-component threads as the multicomponent yarn. This produces a transverse reinforcement structure which has a high level of recovery after being compacted in the press nip. It is of course not necessary that all weft threads of the warp knit fabric embodying the transverse reinforcement structure are multicomponent yarns. It is also conceivable that multicomponent yarns and yarns of other materials are furnished alternately. It is also conceivable to furnish multicomponent yarns simultaneously with yarns of other materials. Further conceivable is the use of monofilament yarns whereby one of the monofilaments is a multicomponent yarn. Moreover it is also conceivable that weft threads comprise staple fiber yarns whereby some of the staple fibers consist of a material which has a lower melting temperature than other fibers in the yarn.

In addition it is conceivable to use yarns which contain PU or are composed of same as well as PA yarns for weft threads. In this case it is for example conceivable to use monofilament yarns of PU and several twisted together monofilament yarns of PA, for example 4-ply threads of PA. In the production of the transverse reinforcement module, PU yarns and PA yarns can be furnished alternately. It is also conceivable to furnish PU yarns and PA yarns simultaneously.

In a transverse reinforcement module with PA yarns and PU yarns the transverse reinforcement is essentially provided by the PA yarns, whereby the PU yarns essentially provide recovery and the damping characteristics of the transverse reinforcement module.

The twisted weft threads can possess a count of 50-500 tex, especially approximately 100-400 tex. A number of, for example, approximately 15-200 tex is conceivable for sewing threads, especially approximately 48-120 tex.

Sewing threads may be in the embodiment of monofilament yarns, especially staple fiber yarns or multifilament yarns.

Additionally it is conceivable that the sewing threads comprise multicomponent yarns or are composed of same. Hereby the multicomponent yarns can comprise one component which has a lower melting temperature than the other component(s). The component having the low melting temperature can be a melt-type adhesive component oftentimes consisting of a thermoplastic material. It is further conceivable that the sewing threads consist of a material having a lower melting point than the materials of the weft threads and that of the fibrous nonwoven structure which is in contact with the base structure. Through these measures together with a thermal treatment, anchoring of the fibrous nonwoven structure into the base structure can be significantly improved. The thermal treatment can hereby occur with or without the effect of pressure.

In order to increase the internal volume of the press felt it can further be advantageous if at least some of the sewing threads are of a material which can be dissolved out of the paper machine clothing after its completion, for example with a solvent. Water, for example is conceivable as a possible solvent.

An additional embodiment of the invention provides that the density of the sewing threads changes in cross direction of the clothing. It is especially conceivable that the density of the sewing threads along the edge areas of the transverse reinforcement module progressing along the longitudinal edges of the base structure is increased compared to the center area of the transverse reinforcement module located between the two edge areas. Due to the increased density of sewing threads in the two edge areas, viewed in cross direction of the clothing, it is for example possible to reduce effects like “edge flipping” or “edge curl”. In addition, wear and tear along the edges of the clothing can be clearly reduced through better anchoring of the fibers of a fibrous nonwoven layer to the base structure.

The inventive paper machine clothing may for example be a press felt which is seamable in the machine. The provision of a transverse reinforcement structure from at least one warp knit fabric leads to a clearly improved anchoring of the fibrous nonwoven structure to the base structure through needling than with press felts which have base structures without knit structure, for example woven base structures. Herewith the so-called “peel back” effect in the seam area can at least be reduced, if not totally eliminated. If, in addition also melt adhesive fibers are used in the transverse reinforcement module, the connection between the base structure and the fibrous nonwoven structure is even further improved.

It can be advantageous, especially for further simplification for the production of the inventive paper machine clothing if the warp knit fabric is produced flat.

The term “produced flat” in this context is to be understood as being delimitation to the terms “produced endless or round”. In this instance the warp knit fabric is limited in its length by two transverse edges progressing transversely to the longitudinal direction of the paper machine clothing.

To adapt the warp knit fabric, the warp knit fabric can be trimmed in its length to approximately the length of the circumference of the clothing which is to be produced.

The transverse reinforcement module preferably comprises at least one warp knit fabric extending on the length of the clothing. The warp knit fabric consists of preferably one single warp knit fabric extending on the length and on the width of the clothing. For especially wide clothing, for example for clothing wider than 6-8 meters it can also be advantageous if the transverse reinforcement module is composed of several, especially two warp knit fabrics arranged adjacent to each other which abut on the longitudinal edges facing each other and which are for example connected with each other through a connecting strip which covers the abutting longitudinal edges, thereby connecting the two warp knit fabrics with each other. A preferred embodiment of the invention provides therefore that the transverse reinforcement module is composed of several warp knit fabrics, extending respectively on the length of the clothing and only on a part of the width of the clothing, whereby the warp knit fabrics located adjacent to each other in cross direction of the clothing are arranged to together make up the width of the clothing.

Alternatively, the transverse reinforcement module may also be formed of one single warp knit fabric which has a lesser width than the width of the clothing and extending essentially in longitudinal direction of the clothing and wound continuously spirally in cross direction of the clothing.

The warp knit fabric may be available in roll form which is trimmed in length according to the requirements, for example the length of the clothing which is to be produced.

In order to make the warp knit fabric extending on the length of the clothing endless, the transverse edges are preferably abutted with each other.

The warp knit fabric is moreover made endless by means of a connecting strip, in that the connecting strip covers the two abutting transverse edges and is interconnected with the warp knit fabric in the area of the two transverse edges.

Since the warp knit fabric which has been trimmed to the desired length tends to fray at the transverse edges which, in the current example, represent the cutting edges, a preferred advancement of the invention provides that in the area of at least one of the transverse edges a material strip is connected with the warp knit fabric whose edge is flush with the transverse edge.

In this context it is preferred if a material strip preventing fraying of the respective transverse edge is provided at both transverse edges.

In order to reduce the tendency of marking on the clothing produced with the material strip(s) and/or connecting strip, the connecting strip and/or the material strip(s) is, or respectively are made of at least one film and/or one spun nonwoven material. This may for example be a film made from polyamide (PA), polyamide copolymer (CoPA), polyethylene terephthalate (PET), polyethylene terephthalate copolymer (CoPET), polyurethane (PU), ethylene vinyl acetate (EVA), polypropylene (PP), thermoplastic polyurethane (TPU) or polyvinyl acetate (PVA). The film can hereby have a base weight in the range of 10-500 g/m², preferably 20-60 g/m². Films consisting of several components are also conceivable, for example PET-PU films, PA-PU films, PET-PA films. Films of this type can have a base weight in the range of 20-500 g/m², preferably 20-60 g/m².

The spun nonwoven material may consist of one or several of the following polymers: CoPA, CoPET, PET, low density polyethylene (LDPE) or PA. The base weight of the spun nonwoven material can hereby be in the range of approximately 10 g/m²-150 g/m². Since at least in the case of one press felt, the base structure is needled with one or more fibrous nonwoven layers during production, it is not necessary with regard to permeability of the completed clothing, that the films are permeable. A preferred design form therefore provides that the film(s) is/are originally—that is during connection with the warp knit fabric—impermeable and are made permeable only through a needling process.

The connecting strip and/or the material strip is connected with the warp knit fabric especially due to the effect of pressure and/or temperature. Here it is particularly advantageous if the connecting strip or respectively strips and/or the material strip melt at a lower temperature than the sewing threads and weft threads of the warp knit fabric. In this context it is also conceivable that the connecting strip(s) and/or material strip are bonded by means of hot wire welding and/or ultrasound welding and/or laser welding.

According to another preferred embodiment of the invention the longitudinal module also comprises a support layer in addition to the already described laid structure of longitudinal threads, arranged at the laid structure of longitudinal threads and connected with same. In this case the support layer extends in particular, like the laid structure of longitudinal threads on the entire width and length of the paper machine clothing.

The support layer can be formed alone or in combination: one fibrous nonwoven layer, one film layer.

The laid structure of longitudinal threads is preferably embedded into the fibrous nonwoven layer. This may be achieved for example by needling the laid structure of longitudinal threads with the support layer which is in the form of a fibrous nonwoven layer. It is possible that, due to the needling process the support layer is destroyed to a great extent. In this case the support layer can assume the task of holding the longitudinal threads of the laid thread structure in position during the additional production process of the felt belt.

A concrete further advancement of the invention provides that the transverse reinforcement module is arranged on the support layer of the longitudinal reinforcement module and that it is bonded with same. In this instance the support layer can for example be designed so that it can be easily connected with the transverse reinforcement module. In this context it is for example conceivable that the fibrous nonwoven layer comprises melt adhesive fibers so that the transverse reinforcement module can be conglutinated with the support layer of the longitudinal reinforcement module through heat effect. The connection between the transverse reinforcement module and the longitudinal reinforcement module can be further improved through the effect of pressure, simultaneously with the heat effect. In order to achieve this it is for example conceivable that the longitudinal reinforcement module and the transverse reinforcement module are guided together around a heated roll or through a heated press nip for the purpose of obtaining the heat effect.

Other integration techniques are of course also possible. It is for example conceivable that the transverse reinforcement module is connected with the longitudinal reinforcement module in that they are needled and/or sewn and/or welded together. It is conceivable in this context that for example the transverse reinforcement module is made endless, and is subsequently connected through needling in the needling machine with a longitudinal reinforcement module which was made or produced endless, as well as with one or more fibrous nonwoven layers. In this case, the integration can occur through needling alone or in combination with another bonding method.

For further simplification of the production of the inventive clothing it is conceivable for the production of the support layer to use a pre-ready-made support web with a narrower width than the width of the clothing. In this case it is for example conceivable that the support web consists of at least one support web extending essentially in longitudinal direction of the clothing and which is continuously spirally wound in cross direction of the clothing.

The support layer in this case is produced in that a support web extending only on part of the provided width of the paper machine clothing is continuously spirally wound in the direction of the provided width of the paper machine clothing until the provided width of the clothing is reached.

During the spiral winding process the edges of the support web facing each other can for example be arranged to abut each other or to overlap in areas.

According to a preferred embodiment of the invention the clothing can comprise a base structure which for example consists of

• • a) Longitudinal reinforcement module extending on the width and length of the clothing,
    • i) a laid structure of longitudinal threads on the width and on the length of the clothing which is formed by at least one longitudinal thread extending essentially in longitudinal direction of the clothing and
    • a support layer which is connected with the laid structure of longitudinal threads and extends across the width and along the length of the clothing and/or
    • ii) a woven or spiralized or knitted textile fabric, as well as
  • b) a transverse reinforcement module having the same length and width as the clothing, whereby the transverse reinforcement module and the longitudinal reinforcement module are arranged on top of each other and the transverse reinforcement module is formed by
    • at least one warp knit fabric extending on the length of the clothing and on the width of the clothing and which is composed of at least one system of weft threads arranged parallel to each other in their longitudinal orientation, and at least one system which extends substantially perpendicular thereto, which is composed of sewing threads that form stitches and into which the weft threads are integrated to form a textile fabric, wherein the weft threads in their longitudinal orientation extend transversely to the longitudinal direction of the clothing and have a greater flexural strength than the sewing threads.

It must be stated in this context that the textile fabric in the form of a woven fabric can be woven flat or round.

It is especially advantageous for the provision of a press felt if on the side of the base structure of the clothing facing the paper side and/or the machine side at least one, especially several fibrous nonwoven layer(s) is/are arranged.

A method to produce the inventive clothing, especially a press felt for a paper machine which has a length and a width may comprise the following steps:

a) provision of a longitudinal reinforcement module with a width and a length which is consistent with the width and length of the clothing which is to be produced,

b) provision of a transverse reinforcement module with a width and a length which is consistent with the width and length of the clothing which is to be produced,

c) locating the longitudinal reinforcement module and the transverse reinforcement module on top of each other and

d) connecting the transverse reinforcement module with the longitudinal reinforcement module.

The inventive method is characterized in that step b) includes at least the following steps: i) provision of at least one warp knit fabric which is composed of at least one system of weft threads arranged parallel to each other, and at least one system which extends substantially perpendicular to the longitudinal direction of the weft threads, which is composed of sewing threads that form stitches and into which the weft threads are integrated to form a textile fabric, wherein the weft threads have a greater flexural strength than the sewing threads and whereby the warp knit fabric has a length which is consistent with the length of the clothing which is to be produced and that step c) includes at least the following step: ii) arranging warp knit fabric and longitudinal reinforcement module on top of each other in a way that the weft threads of the warp knit fabric extend diagonally or transversely to the longitudinal direction of the clothing.

If the warp knit fabric is initially longer than the length of the clothing which is to be produced, it can be shortened in an additional step iii) by trimming the sewing threads of the warp knit fabric to the length of the clothing which is to be produced.

The sequence of steps i)-iii) is herewith not stipulated. It is for example conceivable that first step i), then step ii) and subsequently step iii) are implemented. It is however also conceivable that first step i), then step iii) and lastly, step ii) are implemented.

It is therefore conceivable that at least the one warp knit fabric providing the transverse reinforcement module is initially trimmed to the length of the clothing before the transverse reinforcement module and the longitudinal reinforcement module are placed on top of each other. Moreover it is also conceivable that the warp knit fabric is trimmed to the length of the clothing after it has been placed on the entire length of the clothing on or under the longitudinal reinforcement module. This may occur for example if the warp knit fabric is in the form of a roll product and is unwound during its placement on the longitudinal reinforcement module.

In addition it is conceivable that the transverse reinforcement module which is trimmed to the length of the clothing is initially made endless before it is placed on, and subsequently connected with the longitudinal reinforcement model which was for example made or produced to be endless.

The warp knit fabric and the longitudinal reinforcement module are preferably arranged on top of each other in a way that the sewing threads extend in longitudinal direction and the weft thread perpendicular thereto extend in cross direction of the clothing.

After trimming, the warp knit fabric can be backed on each trimmed edge with the previously described material strip in order to prevent fraying of the respective transverse edge. Before the subsequent needling process in which one or more fibrous nonwoven layers are needled onto the side of the base structure facing the paper and/or machine side, the transverse reinforcement module must be made endless. This can be done by abutting the two transverse edges of the cross thread module against each other and connecting them by means of the already described connecting strips.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a top view of one design form of an inventive transverse reinforcement module for a base structure of a press felt;

FIG. 2 is a cross section of one design form of an inventive press felt with the transverse reinforcement module shown in FIG. 1;

FIG. 3 is one design form of an inventive method to produce an inventive paper machine clothing; and

FIG. 4 is one alternative design form of an inventive method to produce an inventive paper machine clothing.

Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate embodiments of the invention, and such exemplifications are not to be construed as limiting the scope of the invention in any manner.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates a top view of one design form of an inventive transverse reinforcement module 1 for a base structure of a press felt. FIG. 1 is a sectional depiction of the transverse reinforcement module.

Transverse reinforcement module 1 consists of at least one warp knit fabric. The warp knit fabric illustrated in FIG. 1 is composed of a system of weft threads 2 arranged parallel to each other and a system of stitch-forming sewing threads 3 progressing essentially perpendicular thereto. To form a textile fabric the weft threads 3 are integrated into stitches 4 of sewing threads 3.

Weft threads 2 moreover extend in cross direction CMD of the clothing and have greater flexural strength than sewing threads 3. Sewing threads 3 extend in longitudinal direction MD of the clothing.

Longitudinal direction L of the warp knit fabric is established by the longitudinal direction of sewing threads 3, and the cross direction Q of the warp knit fabric is established by the longitudinal direction of weft threads 2. Consequently the warp knit fabric is oriented such that it extends in its longitudinal orientation L in longitudinal direction MD of the clothing.

Weft threads 2 in the current example are in the form of multifilament yarns, which are composed for example of four twisted polyamide (PA) monofilaments. Twisted weft threads 2 possess a count of in the range of approximately 150 tex, whereas the sewing threads have a count in the range of approximately 6, 7-14 tex.

Transverse reinforcement module 1 illustrated in FIG. 1 was produced according to a stitch-bonding process whereby weft threads 2 were supplied during stitch formation by means of parallel weft insertion.

As can be seen from the illustration in FIG. 1, sewing threads 3 form rows 5 of stitches 4 which are arranged parallel to each other and extend perpendicular to weft threads 2, whereby weft threads 2 are integrated into stitches 4. In the current example each of sewing threads 3 of the system forms its own row 5 of stitches.

Moreover, each weft thread 2 is integrated into a stitch 4 of each stitch row 5.

As can be seen from the illustration in FIG. 1, the distance between weft threads 2 is established by the length of stiches 4 in stitch rows 5.

Transverse reinforcement module 1 illustrated in FIG. 1 was produced flat.

FIG. 2 illustrates a cross section of one design form of an inventive paper machine clothing 10 in the embodiment of a press felt with the transverse reinforcement module 1 shown in FIG. 1.

Clothing 10 comprises a load absorbing base structure 11 which extends in longitudinal direction and in cross direction CMD of clothing 10.

In the current example base structure 11 is formed by a longitudinal reinforcement module 12 substantially providing the dimensional stability in longitudinal direction MD of clothing 10, as well as by a transverse reinforcement module 1 substantially providing the dimensional stability in cross direction CMD of clothing 10 which is illustrated in FIG. 1, whereby the transverse reinforcement module 1 is arranged on top of the longitudinal reinforcement module and is interconnected with same.

Longitudinal reinforcement module 12 illustrated in FIG. 2 includes a laid structure of longitudinal threads 13 consisting of several longitudinal threads 14 which extend essentially in longitudinal direction of clothing 10 and are continuously spirally wound in cross direction CMD of clothing 10.

Longitudinal reinforcement module 12 moreover includes a support layer 15 in the embodiment of a fibrous nonwoven layer which is embedded into the laid structure of longitudinal threads 13.

Fibrous nonwoven layer 15 can hereby comprise melt adhesive fibers. In the current example transverse reinforcement module 1 is connected with longitudinal reinforcement module 11 through conglutination with the melt adhesive fibers, in other words, transverse reinforcement module 1 is located on support layer 15 and is connected with same.

In clothing 10 in the embodiment of a press felt two additional fibrous nonwoven layers 17, 18 are arranged on base structure 11 facing the paper side 16 and are connected with base structure 11 through needling. Top fibrous nonwoven layer 17 representing the paper side 16 comprises finer fibers than the middle fibrous nonwoven layer 18 which is located between the top fibrous nonwoven layer 17 and base structure 11.

In addition clothing 10 in the embodiment of a press felt includes a fibrous nonwoven layer 19 on the side of base structure 11 which faces machine side 20 and which is connected with base structure 11 through needling and which represents machine side 20 of clothing 10.

FIG. 3 shows one design form of an inventive method to produce an inventive paper machine clothing.

In the step illustrated in FIG. 3a an endless longitudinal reinforcement module 12, as described for example in FIG. 2 is provided wherein at least one longitudinal thread 14 extending essentially in longitudinal direction MD of clothing 10 is wound continuously spirally between two rolls 21, 22—which are located at a distance from each other and parallel to each other—in cross direction CMD of the clothing. The length of longitudinal reinforcement module 12 is established by the distance between rolls 21, 22. The continuous spiral winding of the at least one longitudinal thread 14 in cross direction CMD occurs until the desired width of the laid structure of longitudinal threads is reached. In addition longitudinal reinforcement module 12 can include a support layer in the embodiment of a fibrous nonwoven layer 15 into which the laid structure of threads is embedded. The resulting longitudinal reinforcement module 12 has a width and a length which are consistent with the width and length of the clothing which is to be produced.

In the step illustrated in FIG. 3 the transverse reinforcement module 1 known from FIG. 1 is described. Here, a warp knit fabric which provides the transverse reinforcement module 1 is arranged on longitudinal reinforcement module 12 in such a way that the weft threads of the warp knit fabric extend in cross direction CMD and the sewing threads extend in longitudinal direction MD of the clothing which is to be produced.

Subsequently the warp knit fabric is trimmed in MD and CMD so that the width and the length of the warp knit fabric are consistent with the width and the length of the clothing which is to be produced.

In trimming the warp knit fabric in MD, the sewing threads of the warp knit fabric are trimmed such that the length of the warp knit fabric corresponds with the length of the clothing which is to be produced.

Prior to trimming the warp knit fabric to the desired length in longitudinal direction MD a material strip 23, 24 is applied onto warp knit fabric in the two areas which are to be shortened respectively with which the trimmed edges—which represent the transverse edges—which are subsequently produced in this process and through which the length of the fabric is limited are protected from fraying.

In the following step shown in FIG. 3c the transverse reinforcement module 1 is made to be endless, by abutting the cut edges, or respectively the cross edges which were produced when trimming the fabric to the desired length in its longitudinal direction and connecting them together with a connecting strip 25 which covers the two abutting cross edges and is connected in the area of the two cross edges with the transverse reinforcement module.

In the context of connecting the longitudinal reinforcement module 12 and transverse reinforcement module 1 it is conceivable to run the sandwich of longitudinal reinforcement module 12 and transverse reinforcement module 1 through a heated press nip 28 which is formed by roll 21 and a for example heated opposite roll 26, so that longitudinal reinforcement module 12 and transverse reinforcement module 1 are bonded together through the effect of pressure and temperature.

Following this, the base structure is completed and as shown in the step illustrated in FIG. 3d can be combined on both sides with one or more fibrous nonwoven layers 17, 18 through needling. Here it is conceivable to stretch the base structure between two rolls 21′, 22′ which are located at a distance from each other and parallel to each other and to run it through needling device 27.

An alternative possibility for the production of an inventive press felt is illustrated in FIGS. 4a-4c.

A longitudinal reinforcement module 33 is produced as an endless belt. This can again be the laid structure of longitudinal threads illustrated in FIG. 3a or a textile fabric in the form of a woven fabric, illustrated in FIG. 4a which is suitable to substantially provide the longitudinal stability of the clothing. When making the woven fabric 33 endless it can be stretched between two rolls 29, 30 for this purpose which are located at a distance from each other and parallel to each other.

An inventive transverse reinforcement module 1 is provided in an additional production step. Here, a warp knit fabric is trimmed to the provided circumferential length of the press felt and is made endless by means of a connecting strip 25 in the embodiment of a film or spun nonwoven material, or by means of hot wire welding. During the process of making the warp knit fabric in the embodiment of transverse reinforcement module 1 endless it can be stretched around two rolls 31, 32 which are positioned parallel to each other.

In the production step illustrated in FIG. 4c endless longitudinal reinforcement module 33, endless transverse reinforcement module 1, as well as fibrous layers 37, 38 which are arranged on top and underneath them are combined with each other through needling. The endless longitudinal reinforcement module 33 and endless transverse reinforcement module 1 are placed on top of each other for this purpose in that they are pulled over two rolls 34, 35 which are located at a distance from each other and parallel to each other. Longitudinal reinforcement module 33 and transverse reinforcement module 1 placed on it, together with the fibrous nonwoven layers 37, 38 are fed into a needling device 36 where the entire arrangement of longitudinal reinforcement module 33, transverse reinforcement module 1 and fibrous nonwoven layers 37, 38 are needled together.

While this invention has been described with respect to at least one embodiment, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.

Claims

1. A papermachine clothing, formed as a press felt, for one of a paper, a cardboard, and a tissue machine, said papermachine clothing comprising:

a load absorbing base structure which extends in a longitudinal direction and a cross direction of the papermachine clothing and which includes a longitudinal reinforcement module and a transverse reinforcement module, said longitudinal reinforcement module substantially providing a dimensional stability of the papermachine clothing in said longitudinal direction, said transverse reinforcement module substantially providing a dimensional stability of the papermachine clothing in said cross direction of the papermachine clothing, said transverse reinforcement module and said longitudinal reinforcement module being arranged one on top of the other, said transverse reinforcement module being at least one warp knit fabric which includes (a) at least one system of a plurality of weft threads arranged parallel to each other in a longitudinal orientation of said plurality of weft threads, and (b) at least one system which extends substantially perpendicular thereto and which includes a plurality of sewing threads that form a plurality of stitches and into which said plurality of weft threads are integrated to form a textile fabric, said plurality of weft threads in said longitudinal orientation extending diagonally to said longitudinal direction of the papermachine clothing and having a greater flexural strength than said plurality of sewing threads.

2. The papermachine clothing according to claim 1, wherein said plurality of weft threads in said longitudinal orientation extend transversely to said longitudinal direction of the papermachine clothing.

3. The papermachine clothing according to claim 1, wherein said longitudinal reinforcement module includes a laid structure of longitudinal threads which includes at least one said longitudinal thread extending essentially in said longitudinal direction of the papermachine clothing and being wound continuously spirally in said cross direction of the papermachine clothing.

4. The papermachine clothing according to claim 1, wherein said at least one warp knit fabric is formed from one single said system of said plurality of weft threads arranged parallel to each other and from one single said system including said plurality of sewing threads that form said plurality of stitches.

5. The papermachine clothing according to claim 1, wherein said at least one warp knit fabric is produced by stitch bonding processes, wherein said plurality of weft threads are delivered during stitch formation by way of parallel weft insertion.

6. The papermachine clothing according to claim 1, wherein said plurality of sewing threads form a plurality of rows of said plurality of stitches, said plurality of rows being arranged parallel to each other and extending perpendicular to said plurality of weft threads, said plurality of weft threads being integrated into said plurality of stitches.

7. The papermachine clothing according to claim 6, wherein each of said plurality of sewing threads forms a respective one of said plurality of rows of stitches.

8. The papermachine clothing according to claim 6, wherein each of said plurality of weft threads is integrated into a respective one stitch of each of said plurality of rows of stitches.

9. The papermachine clothing according to claim 6, wherein a distance of said plurality of weft threads to each other is determined by a length of said plurality of stitches in said plurality of rows of stitches.

10. The papermachine clothing according to claim 1, wherein said plurality of weft threads are formed by a plurality of multifilament yarns each of which is formed by a plurality of monofilaments which are twisted together.

11. The papermachine clothing according to claim 1, wherein said warp knit fabric is produced flat.

12. The papermachine clothing according to claim 1, wherein said at least one warp knit fabric extends on a length of the papermachine clothing.

13. The papermachine clothing according to claim 1, wherein said transverse reinforcement module includes one single said warp knit fabric extending on a length and on a width of the papermachine clothing.

14. The papermachine clothing according to claim 1, wherein said transverse reinforcement module includes a plurality of said warp knit fabric extending respectively on a length of the papermachine clothing and only on a part of a width of the papermachine clothing, said plurality of warp knit fabrics located adjacent to each other in said cross direction of the papermachine clothing being arranged to together make up said width of the papermachine clothing.

15. The papermachine clothing according to claim 1, wherein said at least one warp knit fabric includes two transverse edges progressing transversely to said longitudinal direction of the papermachine clothing, said at least one warp knit fabric further including a length which is limited by said two transverse edges progressing transversely to said longitudinal direction of the paper machine clothing.

16. The papermachine clothing according to claim 15, wherein said two transverse edges are abutted in order to make said at least one warp knit fabric extending on a length of the papermachine clothing endless.

17. The papermachine clothing according to claim 16, further including a connecting strip, wherein said at least one warp knit fabric is made endless by way of said connecting strip which covers said two transverse edges which are abutting, said connecting strip being connected with said transverse reinforcement module in an area of said at least one warp knit fabric including said two transverse edges.

18. The papermachine clothing according to claim 17, wherein said connecting strip is made of at least one of (a) at least one film and (b) one spun nonwoven material.

19. The papermachine clothing according to claim 17, wherein said connecting strip is connected with said at least one warp knit fabric due to an effect of at least one of pressure and temperature.

20. The papermachine clothing according to claim 15, further including a material strip including an edge, wherein in an area of said at least one warp knit fabric including at least one of said two transverse edges said material strip is connected with said at least one warp knit fabric such that said edge is flush with said one of said two transverse edges.

21. The papermachine clothing claim 20, wherein said material strip is made of at least one of (a) at least one film and (b) one spun nonwoven material.

22. The papermachine clothing according to claim 20, wherein said material strip is connected with said at least one warp knit fabric due to an effect of at least one of pressure and temperature.

23. The papermachine clothing according to claim 1, wherein said longitudinal reinforcement module includes a laid structure of longitudinal threads which includes at least one said longitudinal thread extending essentially in said longitudinal direction of the papermachine clothing and being wound continuously spirally in said cross direction of the papermachine clothing, said longitudinal reinforcement module including a support layer arranged at said laid structure of longitudinal threads.

24. The papermachine clothing according to claim 23, wherein said support layer is formed by at least one of one fibrous nonwoven layer and one film layer.

25. The papermachine clothing according to claim 24, wherein said laid structure of longitudinal threads is embedded into said fibrous nonwoven layer forming said support layer.

26. The papermachine clothing according to claim 24, wherein said fibrous nonwoven layer includes a plurality of melt adhesive fibers.

27. The paper machine clothing according to claim 24, wherein said transverse reinforcement module is arranged on, and is bonded with, said support layer of said longitudinal reinforcement module.

28. The papermachine clothing according to claim 24, wherein said laid structure of longitudinal threads is needled together with said support layer, said support layer being formed as said fibrous nonwoven layer.

29. The papermachine clothing according to claim 23, wherein said support layer includes at least one support web which extends essentially in said longitudinal direction of the papermachine clothing and which is continuously spirally wound in said cross direction of said papermachine clothing.

30. The papermachine clothing according to claim 1, wherein said transverse reinforcement module is connected with said longitudinal reinforcement module in that said transverse reinforcement module and said longitudinal reinforcement module are at least one of needled, sewn, and welded together.

31. The papermachine clothing according to claim 1, wherein the papermachine clothing includes a paper side and a machine side, said base structure including a first side facing said paper side and a second side facing said machine side, at least one of (a) the papermachine clothing including a first fibrous nonwoven layer which is arranged on said first side, and (b) the papermachine clothing including a second fibrous nonwoven layer which is arranged on said second side.

32. A method to produce a papermachine clothing, formed as a press felt for a papermachine, for one of a paper, a cardboard, and a tissue machine, said method comprising the steps of:

providing that the papermachine clothing includes a load absorbing base structure which extends in a longitudinal direction and a cross direction of the papermachine clothing and which includes a longitudinal reinforcement module and a transverse reinforcement module, said longitudinal reinforcement module substantially providing a dimensional stability of the papermachine clothing in said longitudinal direction, said transverse reinforcement module substantially providing a dimensional stability of the papermachine clothing in said cross direction of the papermachine clothing, said transverse reinforcement module and said longitudinal reinforcement module being arranged one on top of the other, said longitudinal reinforcement module including a laid structure of longitudinal threads which includes at least one said longitudinal thread extending essentially in said longitudinal direction of the papermachine clothing and being wound continuously spirally in said cross direction of the papermachine clothing, said longitudinal reinforcement module including a support layer arranged at said laid structure of longitudinal threads, said support layer including at least one support web which extends essentially in said longitudinal direction of the papermachine clothing and which is continuously spirally wound in said cross direction of said papermachine clothing, said transverse reinforcement module being at least one warp knit fabric which includes (a) at least one system of a plurality of weft threads arranged parallel to each other in a longitudinal orientation of said plurality of weft threads, and (b) at least one system which extends substantially perpendicular thereto and which includes a plurality of sewing threads that form a plurality of stitches and into which said plurality of weft threads are integrated to form a textile fabric, said plurality of weft threads in said longitudinal orientation extending one of diagonally and transversely to said longitudinal direction of the papermachine clothing and having a greater flexural strength than said plurality of sewing threads; and

one of abutting and overlapping, during a spiral winding process, a plurality of edges of said support web which face each other.

33. A method to produce a papermachine clothing formed as a press felt for a papermachine, the papermachine clothing having a length and a width, said method comprising the steps of:

providing a longitudinal reinforcement module and a transverse reinforcement module, said longitudinal reinforcement module having a width and a length which is consistent with the width and the length of the papermachine clothing which is to be produced, said transverse reinforcement module having a width and a length which is consistent with the width and the length of the papermachine clothing which is to be produced;

forming said transverse reinforcement module such that said transverse reinforcement module includes at least one warp knit fabric which includes (a) at least one system of a plurality of weft threads arranged parallel to each other, and (b) at least one system which extends substantially perpendicular to a longitudinal direction of said plurality of weft threads and which includes a plurality of sewing threads that form a plurality of stitches into which said plurality of weft threads are integrated to form a textile fabric, said plurality of weft threads having a greater flexural strength than said plurality of sewing threads, said at least one warp knit fabric having a length which is consistent with the length of the papermachine clothing which is to be produced;

locating said longitudinal reinforcement module and said transverse reinforcement module on top of each other, said step of locating including arranging said at least one warp knit fabric and said longitudinal reinforcement module on top of each other in a way that said plurality of weft threads of said at least one warp knit fabric extend one of diagonally and transversely to a longitudinal direction of the papermachine clothing; and

connecting said transverse reinforcement module with said longitudinal reinforcement module.