EP2072668A1 - Belt for a production machine for sheet material and method for manufacturing such a belt - Google Patents

Abstract

The belt (10) has a carrying structure (12), and a layer (20) of fiber material providing a sheet material contact surface (26). A layer (22) of fiber material is provided between the carrying structure and the layer (20), where polymer materials (24, 28) are comprised in the latter fiber material. The polymer materials are provided as elastomer i.e. polyurethane, and form a film, which partially covers a part of the fiber of the layer (22). The layer (22) of fiber material is rough than the layer (20) of the fiber material. An independent claim is also included for a method for manufacturing a belt for a machine for manufacturing the sheet material.

Description

The present invention relates to a belt for a machine for producing sheet material, in particular paper or cardboard, and to a method for producing such a belt.

Such a band generally comprises a support structure, for example formed as a fabric or scrim or so-called spiral link structure. On a web material contact side of this support structure is fiber material, for example in the form of multiple layers of fiber material, provided and firmly connected to the support structure generally by needling. Such belts, which can be provided, for example, in an endless configuration, are mainly used in so-called press sections in paper machines, in which the belts are moved through press nips together with the web material to be produced. In this case, liquid is pressed out of the web material and taken up in the band or removed via the band. In order to improve the liquid absorption capacity of the belt, it is known to provide between the support structure and a fiber layer which provides a sheet material contact surface, a layer with a comparatively large void volume, in which the water pressed out of the sheet material can be absorbed. These layers may for example also be formed as a fabric, but this has the disadvantage that due to the positioning of a fabric layer relatively close to the web material contact surface, the fabric structure is evident in the web material to be produced. Alternatively, it is known to incorporate membranes of polymeric material or the like formed with a substantially planar structure and a plurality of openings are. However, these membranes are very expensive to produce.

It is the object of the present invention to provide a belt for a machine for producing sheet material, in particular paper or cardboard, and a method for producing such a belt, with which increases the volume for receiving liquid without the risk of marking the web material to be produced can be.

According to a first aspect of the present invention, this object is achieved by a belt, in particular press felt, for a machine for producing web material, in particular paper or cardboard, comprising a support structure, a layer of fiber material providing web material contact surface and at least one between the support structure and the Layer of fibrous material disposed in the sheet material contact surface, in which polymer material is contained, which forms a film which at least partially covers at least part of the fibers of this layer.

In the band constructed according to the invention, a layer which is arranged between the layer providing the band material contact surface and the support structure, ie a layer which is located further inside in the volume region of the band and should provide a large volume for receiving liquid, with basically fibrous structure , So, for example, as a felt or fleece, constructed and interspersed with a polymer material which covers fibers of this layer at least partially with a film. This structure, due to its pore structure, leaves sufficient volume to contain liquid, but avoids a regular pattern which could be evident in the web material being made. The fibers of the layer of fiber material partially as a film-coating polymer material is in this case firmly bonded to the fibers.

Between the sheet material contact surface providing position Fiber material and the support structure may be arranged in addition to the polymer material containing layer one or more further layers of fiber material. This layer (s) may also contain polymer material. It is also possible that this layer (s) contains no polymer material. If multiple layers are present, one or more layers of polymeric material may be included, as some or more of the bearings may contain no polymeric material.

Preferably, the polymer material is disposed on the entire thickness of the fibrous material layer containing it.

Preferably, at least 70% of the fibers of the fiber layer are at least 70% coated with the film. Furthermore, it is advantageous if all the fibers of the fiber layer are completely coated with the film of the polymer material.

In order to provide a particularly good water storage volume, it is expedient if the layer of fiber material containing the polymer material contains fibers in the range of 44 dtex or more. By way of example, the layer of fibrous material containing the film forming polymeric material may contain fibers in the range of 44 to 200 dtex. Preferably, the layer containing the polymeric material is composed of fibers in the range of 44 to 200 dtex. Particularly preferably, the layer containing the polymer material is composed of fibers in the range from 44 to 140 dtex.

Depending on the particular process control during the production of the strip according to the invention, some of the polymer material which is introduced into the at least one layer of fibrous material disposed between the support structure and the layer of fibrous material providing the web material contact surface can be interleaved, for example during the needling process of the layers The web material contact surface providing position of fiber material pass.

An embodiment of the invention provides that less polymer material is contained in the layer of fiber material providing the web material contact surface than in the at least one layer of fiber material arranged between the latter and the support structure.

Preferably, in the layer of fiber material providing the web material contact surface there is substantially no polymer material attached to the fibers. Essentially no polymer material is intended here to mean that less than 10%, in particular less than 5%, of the weight of this layer is due to the polymer material.

Preferably, the layers of fibrous material are bonded to the support structure by needling.

Preferably, the polymer material was applied in the at least one layer of fiber material in the form of an aqueous dispersion and subsequently removed from the liquid.

A further embodiment of the invention provides that a further polymer material is contained in the layer of fibrous material which provides the web material contact surface, which in particular was introduced into the web from the web material contact surface and subsequently melted, and after its solidification with this layer a fluid-permeable one Composite structure forms. In this case, the further polymer material can be applied in particular in the form of an aqueous dispersion of particles of the further polymer material. In this case, the liquid is subsequently removed from the dispersion and then the further polymaterial is melted and solidified again. The melting can take place, for example, by hot calendering, which additionally achieves smoothing of the web material contact surface.

Thus, a fluid-permeable composite structure is formed from the fibers of the fiber layer and the further polymer material by the further polymer material only partially filling and / or bridging voids between fibers of the fiber layer.

In this case, the further polymer material forms in particular a permeable polymer-coherent structure or a one-piece and permeable polymer layer. A one-piece polymer layer is to be understood here as meaning a polymer layer which is formed from a single coherent piece. To provide the permeability, the polymer layer has openings extending therethrough, the openings in the polymer layer being formed by the polymer material forming the polymer layer only partially filling and / or bridging voids formed between fibers of the fiber layer. To demonstrate the integrity of the permeable polymer layer, the fiber material, if it is, for example, of polyamide, for example, be dissolved out by means of formic acid.

Preferably, the polymer material forming the film has a higher melting temperature than the other polymeric material which fills and / or bridges voids formed between fibers of the web material contact surface providing fiber layer.

It is advantageous if the further polymer material, viewed from the web material contact surface, extends into the layer of fibrous material that provides this, up to a maximum depth of 500 μm, preferably 300 μm, particularly preferably 200 μm. As a result, a band is created, which has both a high "inner" water storage volume as well as a smooth and thus marking low web material contact surface.

For example, it may be provided that the polymer material with respect to the fibrous material layer containing it has at least 10% by weight. In order to be able to ensure the desired recovery property of this band, in particular in the layer containing the polymeric material, it is proposed that the polymer material have a hardness in the range from 50 to 97 Shore A.

Preferably, the polymer material is an elastomer, in particular a polyurethane.

Preferably, the structure formed by the at least one layer of fiber material with the fibers of this layer at least partially covering film is elastically compressible, so that after passing through a press nip the tape returns very quickly to its original shape and thus the risk of rewetting is largely excluded ,

Preferably, the band is permeable to fluid.

In order to further increase the elasticity of the tape according to the invention, it makes sense if fibers of the at least one layer of fiber material are interconnected at intersections by the polymer material.

Furthermore, it may be useful to increase the elasticity of the tape when fiber bundle forming portions of fibers in the at least one layer of fibrous material are bonded together by the polymeric material.

1. a) Bereitstellen einer Tragestruktur und mehrere Lagen aus Fasermaterial,
2. b) Einbringen von Polymermaterial in zumindest eine der Lagen aus Fasermaterial,
3. c) Anordnen der zumindest einen das Polymermaterial enthaltenden Lage aus Fasermaterial zwischen der Tragestruktur und der eine Bahnmaterialkontaktfläche bereitstellenden Lage aus Fasermaterial,
4. d) Bewirken, dass das in der Lage aus Fasermaterial (22) eingebrachte Polymermaterial (24) einen Film bildet, der zumindest einen Teil der Fasern (22) dieser Lage zumindest teilweise überzieht,
5. e) festes Verbinden der Lagen aus Fasermaterial (20, 22) mit der Tragestruktur (12).

The above-mentioned object is further achieved by a method for producing a belt for a machine for producing web material, in particular according to one of the preceding claims, comprising the measures:

1. a) providing a support structure and a plurality of layers of fiber material,
2. b) introducing polymer material into at least one of the layers of fiber material,
3. c) arranging the at least one layer of fibrous material containing the polymer material between the support structure and the layer of fiber material providing a web material contact surface,
4. d) causing the polymeric material (24) introduced in the fiber material layer (22) to form a film which at least partially covers at least a portion of the fibers (22) of that layer,
5. e) firmly connecting the layers of fiber material (20, 22) with the support structure (12).

The method according to the invention can be carried out on the one hand, the measure d) before the measure e) is executed. This means that after the polymer material has been introduced into at least one layer of fibrous material, the polymer material introduced into at least one of the layers of fibrous material will at least partially envelop fibers of that layer before the layers of fibrous material and the support structure are firmly bonded together.

Alternatively, it is conceivable that the measure e) before the measure d) is executed. This means that after the polymer material has been introduced into at least one layer of fibrous material, the layers of fibrous material and the support structure are first firmly bonded to each other before causing the polymer material introduced into at least one of the layers of fibrous material to at least partially encase fibers of that layer.

It is also conceivable for the polymer material to be introduced into the at least one layer of fiber material before it is arranged above the support structure and under the layer of fiber material which provides the web material contact surface.

Alternatively, it is conceivable to arrange at least one layer of fiber material on the support structure, then to introduce the polymer material into it and then to subsequently arrange the layer of fiber material providing the web material contact surface over the fiber layer with polymer material.

Preferably, there is substantially no polymeric material in the fibrous material layer providing the web material contact surface.

To increase the elasticity of the band, an embodiment of the method according to the invention provides that after and / or during the measure d) the layer of fiber material is compressed with the introduced polymer material under the effect of heat.

Furthermore, for example, the procedure can be such that the measure b) comprises the provision of polymer material in at least one layer of fiber material by applying a preferably aqueous dispersion of particulate polymer material to this layer of fiber material.

Furthermore, measure d) preferably comprises the removal of liquid, in particular water, from the aqueous dispersion of particulate polymer material, thereby causing the polymer material to coat at least a portion of the fibers of the at least one layer of fibrous material.

The measure e) may include the needling of the layers of fiber material with the support structure.

The layer of fibrous material in which the polymeric material is disposed, which at least partially covers at least a portion of the fibers of the sheet, forming a film, may have fibers in the region of 44dtex or more.

By way of example, the at least one layer comprises fibers in the range of 44 to 200 dtex. Preferably, this layer of fibers in the range of 44 to 200 dtex, preferably in the range 44 to 140dtex, constructed. When such fibers are provided, it is ensured that, in principle, a comparatively coarse structure of this layer is present, that is to say that the void fraction in the volume is large compared to layers of fiber material with fibers having smaller dtex values, and thus provides a correspondingly large volume for receiving liquid becomes. In particular, it may be provided that the at least one layer of fibrous material containing the particulate polymer material is coarser than the layer of fibrous material providing the web material contact surface. In this way it is ensured that a very fine structure is present at the web material contact surface, in which the danger that the individual fibers of the layer of fiber material are apparent in the web material to be produced, practically does not exist.

The support structure may be fabric-like or random. An education with a so-called spiral link structure is basically possible, as well as any other structure, which ensures that the forces resulting from the advancement of such a band can be accommodated in this support structure.

One or all layers of fiber material may be formed as a nonwoven layer.

Fig. 1

eine Prinzip-Schnittansicht eines erfindungsgemäß aufgebauten Bands,

Fig. 2

eine Elektronenmikroskopaufnahme einer derartigen Lage aus Fasermaterial darin enthaltenem Polymermaterial;

The present invention will be described below in detail with reference to the accompanying drawings. It shows:

Fig. 1

a principle sectional view of an inventively constructed bands

Fig. 2

an electron micrograph of such a layer of fiber material contained therein polymer material;

This in Fig. 1 shown in section tape 10, which can be used for example in a press section of a paper machine contains as the essential forces receiving structure a support structure 12, which may be formed, for example, as a fabric or as a scrim or as a spiral link structure. At a machine contact side 14, a layer 16 of fiber material is connected to the support structure 12. On a side facing the web material contact surface 26 side 18 of the support structure 12, two layers 20, 22 of fiber material with the support structure 12 are connected. The bonding of these layers 16, 18, 20 of fibrous material to the support structure 12 can be done for example by needling, so that individual fibers of this example fleece-like or felt-like layers 16, 20, 22 are pulled into each of the next layer and the support structure and thus lead to a stable connection.

The layer 22 of fibrous material lying between the support structure 12 and the layer 20 of fiber material contains a polymer material 24 which forms a film which at least partially covers fibers of this layer 22. The polymeric material 24 is particularly an elastomeric polymer material such as polyurethane or the like. The fibrous material layer 20, which also provides a web material contacting surface 26, does not substantially contain such polymeric material.

This in the Fig. 1 shown band 10 can be prepared so that first the support structure 12, for example, produced in an endless configuration and stretched over two rollers. Subsequently, the layer 22 is first applied after the polymer material 24 has been introduced into this, for example, by spiraling over the after externally exposed side of the support structure 12 is wound until it is completely covered.

The introduction of polymer material 24 in the layer 22 of fiber material may in this case comprise the application of a preferably aqueous dispersion of particulate polymer material 24 to this layer 22.

Following this, then the layer 20 is e.g. Applied in a similar manner. The layer 16 may have previously been provided on the support structure 12 or may be omitted.

After the support structure 12, in particular with the layers 20, 22 in the in Fig. 1 As shown arrangement is connected by needling, causing the introduced in the position of fibrous material 22 polymer material 24 to form a polymer film fibers of this layer 22 at least partially enveloped. The effecting may include the removal of liquid, in particular water, from the aqueous dispersion of particulate polymer material 24.

Simultaneously or subsequently with this method step, the layer of fiber material 22 can be compressed with the introduced polymer material 24 under the action of heat. This compacts the structure.

The partial enveloping of the fibers with the polymer material 24 results in a comparatively rigid structure which, however, is elastically deformable due to the elasticity of the polymer material and which is formed by the layer 22 of fiber material with polymer material 24 contained therein. This structure returns after passing through press nips very quickly back to its original shape and thus provides sufficient volume to accommodate the pressed through the layer 22 through liquid and then to the back, so the Machine contact page 14 to submit.

In order to obtain the desired distribution of the polymer material 24 in the volume range of the layer 22 of fiber material in the above-described procedure for producing such a belt 10, that is, for example, the in Fig. 1 It is also possible to proceed to obtain visible, more or less uniform penetration with polymer material 24 in such a way that, as already described, a preferably aqueous dispersion of polymer particles 24 is applied to the layer 22. The proportion should be such that the polymer material 24 has at least 10 percent by weight relative to the layer 22 of fibrous material. The proportion by weight may be, for example, 50 to 600 g / m ² . The polymer material 24 used, for example polyurethane, may have a hardness in the range from 55 to 100 Shore A. Furthermore, it can be provided that the layer 22 is constructed of fiber material with fibers in the range of 44 to 200 dtex. This ensures that this layer 22 is sufficiently coarse, that is, has a very large void fraction, so as to obtain the desired liquid receiving cavity therein even after the provision of the polymer material 24 (see FIG. 2 ). The layer 20 of fiber material which provides the web material contact surface 26 is formed finer, that is, for example, with fibers having a dtex value of less than 40 and also a smaller void fraction, ie a lower porosity than the layer 22.

It should be noted that various variations can be made in the band described above without departing from the principles of the present invention. For example, more than the two layers of fibrous material shown may be provided on the web material contact side of the support structure 12, however, in a variety of embodiments, that layer or layers of fibrous material in which polymer material is to be included will not provide the web material contact side, that is, at least a location from Fiber material over this lies. When providing several layers of fiber material with polymer material contained therein, of course, the polymer portion or the polymer material used can differ to obtain a stepped patterning, in which, for example, the void content, ie the porosity of the individual layers in the direction of support structure increases.

Claims (25)

A belt, in particular press felt, for a machine for producing web material, in particular paper or cardboard, comprising a support structure (12), a fibrous material layer (20) providing web material contact surface (26) and at least one between the support structure (12) and the web material contact surface (26) providing layer (20) of fibrous material, in which polymer material (28) is contained, which forms a film which at least partially covers at least part of the fibers of this layer (22). Tape according to claim 1,
characterized in that the layer of fibrous material (22) containing the polymer material (28) contains fibers in the range of 44dtex or more. Tape according to claim 2,
characterized in that the layer of fibrous material (22) containing the polymer material (28) comprises fibers in the range of 44 to 200 dtex, preferably composed of fibers in the range of 44 to 200 dtex, more preferably fiber in the range of 44 to 140 dtex is. A belt according to any one of claims 1 to 3,
characterized in that in a layer of fiber material (20) providing a web material contact surface (26) there is substantially no attached to the fibers Polymer material is included. Tape according to one of claims 1 to 4,
characterized in that the polymer material (28) in the at least one layer of fiber material (22) applied in the form of an aqueous dispersion and this was subsequently removed from the liquid. Tape according to one of claims 1 to 5,
characterized in that in a layer of fiber material (20) providing a web material contact surface (26) is contained a further polymer material which has been introduced in particle form from the web material contact surface (26) into this layer and subsequently melted to form a fluid-permeable composite structure with this situation (22). Tape according to claim 6,
characterized in that the further polymer material, viewed from the web material contact surface (26), extends into the layer of fibrous material (20) which provides it to a depth of 500 μm, preferably 300 μm, particularly preferably 200 μm. Tape according to one of claims 1 to 7,
characterized in that the polymer material (28) has at least 10% by weight with respect to the fibrous material layer (22) containing it. Tape according to one of claims 1 to 8,
characterized in that the polymeric material (28) has a hardness in the range of 50 to 97 Shore A. Tape according to one of claims 1 to 9,
characterized in that the polymer material (28) is an elastomer, in particular polyurethane. Tape according to one of claims 1 to 10
characterized in that fibers of the at least one layer of fiber material (22) are interconnected at intersections by the polymeric material (28). Tape according to one of claims 1 to 11,
characterized in that fiber bundle forming portions of fibers in the at least one layer of fibrous material (22) are interconnected by the polymeric material (28). Tape according to one of claims 1 to 12,
characterized in that the at least one layer of fiber material (22) formed with the fibers of this layer at least partially coating film structure is elastically compressible. A belt according to any one of claims 1 to 13,
characterized in that the layers of fiber material (20, 22) are connected to the support structure (12) by needling. Method for producing a belt for a machine for producing web material, in particular according to one of the preceding claims, comprising the measures: a) providing a support structure and a plurality of layers of fiber material, b) introducing polymer material into at least one of the layers of fiber material, c) arranging the at least one polymer material containing Layer of fibrous material between the support structure and the web material contact surface providing layer of fiber material, d) causing the polymeric material (24) introduced in the fiber material layer (22) to form a film which at least partially covers at least part of the fibers of that layer (22), e) firmly connecting the layers of fiber material (20, 22) with the support structure (12). Method according to claim 15,
characterized in that the measure d) is carried out before the measure e). Method according to claim 15,
characterized in that the measure e) is carried out before the measure d). Method according to one of claims 15 to 17,
characterized in that substantially no polymer material (24) is contained in the layer of fiber material (20) providing the web material contact surface (26). Method according to one of claims 15 to 18,
characterized in that after and / or during the measure d) the layer of fiber material (22) is compressed with the introduced polymer material (24) under the action of heat. Method according to one of claims 15 to 19,
characterized in that the measure b) the introduction of polymer material (24) in at least one layer of fiber material (22) by applying a preferably aqueous dispersion of particulate polymer material (24) to said nonwoven web (22). Method according to one of claims 15 to 20,
characterized in that the measure e) comprises needling the layers of fiber material (20, 22) with the support structure (12). Method according to one of claims 15 to 21,
characterized in that the layer of fibrous material (22) containing at least one polymeric material (24) contains fibers in the range of 44 to 200 dtex, preferably fibers in the range 44 to 200 dtex, more preferably fibers in the range 44 to 140 dtex is constructed. Method according to one of claims 15 to 22,
characterized in that the at least one layer of fibrous material (22) containing the polymer material (24) is coarser than the fibrous material layer (20) providing the web material contact surface (26). Method according to one of claims 15 to 23,
characterized in that the support structure (12) is fabric-like or random. Method according to one of claims 15 to 245,
characterized in that the measure d) comprises the removal of liquid, in particular water, from the aqueous dispersion of particulate polymer material (24).

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