Composite material, roller and blade

Abstract

Composite material comprising a matrix material (5) and a reinforcing structure (6) which is embedded in the matrix material (5), characterized in that the reinforcing structure (6) comprises or consists of a mixed textile (1), wherein the mixed textile (1) comprises both sustainable fibers (2) and reinforcing fibers (3).

Description

The invention relates to a composite material according to the preamble of claim 1, and to a roller and a blade-in particular a doctor blade or doctor blade-using such a composite material.In machines for producing or processing fibrous webs, such as paper machines, coating installations or else printing machines, components which consist wholly or partly of so-called composite materials are used at various points. In these composite materials, a reinforcing structure is embedded in a surrounding matrix material.In papermaking machines, use is usually made of composite materials in which the matrix material consists of one or more polymers. In polymer-based composite materials, fibers, fabrics or other textiles are used for producing correspondingly reinforced materials, with the aim of achieving a higher mechanical load capacity compared to the non-reinforced composite material. Such composite materials are used in paper machines, for example, for producing roll coverings (base layer or top layer) or scraper blades.With the increasing importance of sustainability and the aim of avoiding or at least reducing emissions which are harmful to climates, various attempts are also being made to make these composite materials more durable or to find alternative materials. However, it must always be ensured that the mechanical or chemical properties of these alternative materials are still sufficient for the intended use.For example, glass fibers and corresponding glass fiber textiles are frequently used as the reinforcing structure. A disadvantage here is that-according to current knowledge-no glass fibers and corresponding glass fiber textiles can be produced from recycled glass without the mechanical performance of such glass fibers and corresponding glass fiber textiles being compromised. The use of biodegradable glass fibers is described in the document EP 4 108 828. However, these only address the topic of disposal. During production, these glass fibers do not have a better sustainability balance than conventional glass fibers.In order to improve sustainability, in particular in order to reduce CO 2 emissions, attempts are also made to reduce the use of fossil raw materials when using polymer fibers, for example fibers made of poly(ethylene terephthalate) (PET) or polyamides (PAs). Thus, for example, in the international application WO 2021 / 074492 A1, a composite material for a roll cover is described, in which reinforcing fibers are partially produced from recycled material. Alternatively or additionally, the reinforcing fibers can also be replaced by natural fibers such as cotton, flax, hemp or similar fibers.In the context of this application, polymer fibers which are produced from recycled material or on the basis of renewable raw materials (e.g. bio-polyamide from castor oil) and natural fibers, such as e.g. cotton, flax or hemp fibers, are to be summarized under the term "sustainable fibers". These sustainable fibers have a reduced CO 2- footprint over the entire lifetime compared to polymer fibers made of fossil raw materials. Fibers other than "sustainable fibers" as defined above are referred to by the term "reinforcing fibers.". These terms have been chosen for the purpose of ease of readability. The terms "fibers" and "filaments" are used interchangeably in this application unless explicitly stated otherwise.The described fibers (lasting and reinforcing) can be used in various forms, for example as monofilaments, multifilaments or twisted yarns. In multifilaments, the individual filaments can be twisted together or guided side by side in an untwisted manner. In contrast to monofilaments, multifilaments and threads can occur that a multifilament or thread has both lasting fibers and reinforcing fibers.Likewise, the terms "composite material" and "composite material" are used interchangeably.The reinforced use of such sustainable fibers, in particular also for composite materials for use in the paper industry, is therefore desirable. However, it must be ensured that the components produced thereby continue to have the required mechanical properties. Finally, the production of the composite materials or of the components must also be possible efficiently and reproducibly. The object of the present invention is to overcome these difficulties.The object is achieved according to the invention by an embodiment according to the independent claims. Further advantageous embodiments of the present invention are found in the dependent claims.A composite material is proposed here which comprises a matrix material and a reinforcing structure which is embedded in the matrix material. According to the invention, it is provided that the reinforcing structure comprises or consists of a mixed textile, wherein the mixed textile comprises both sustainable fibers and reinforcing fibers.The combination of sustainable fibers with reinforcing fibers makes it possible to improve the possible deficiencies of the sustainable fibers, e.g. with regard to strength, stiffness or similar properties, by adding reinforcing fibers to such an extent that the resulting mixed textile or the composite material has sufficient property values for the later use. In comparison to the use of exclusively reinforcing fibers, the composite material has a significantly better climate balance due to the proportion of lasting fibers.By varying the proportion of the lasting fibers or the arrangement of the reinforcing fibers in the mixed fabric, both the material properties and the climate balance of the material can be optimized.The mixed textile can advantageously comprise or consist of a woven or laid scrim. Alternatively or additionally, the mixed textile can also comprise or consist of a knitted fabric or a nonwoven.The mixed textile can consist of one or more textile layers. These may be similar textile layers (e.g. two woven fabric layers) or different textile layers (e.g. a mixed woven fabric and a nonwoven fabric).It can be provided that only one of the textile layers has a combination of lasting fibers and reinforcing fibers, or a plurality of textile layers, in particular all of them.Different textile layers may be separate or connected to each other.The use of a textile as a reinforcing structure offers several advantages. On the one hand, a textile can be processed very well and can be wound around a roll body more easily and with more accurate positioning, for example in the form of a textile strip, than individual fibers or threads.On the other hand, in a textile, the lasting fibers and the reinforcing fibers can be prefabricated very easily and precisely, both in terms of their number and in their arrangement relative to one another. In the case of a mixed fabric, this can be effected, for example, via the weaving pattern.This ensures that during the production of the composite material (or of the component comprising this composite material), the reinforcing structure has the correct desired properties without the operating personnel having to be particularly trained or experienced.Thus, it can be advantageous, for example, if the mixed textile comprises or consists of a mixed fabric, wherein the reinforcing fibers are provided only as warp threads or only as weft threads. This can be advantageous in particular if the strength-enhancing properties of the reinforcing fibers are not required isotropically, but only in a specific direction. A very advantageous variant in this regard is if all warp threads in the mixed fabric are configured as conventional, reinforcing fibers, and lasting fibers are used only for the weft threads. Thus, even smaller amounts of the mixed fabric can be produced economically expedient, since no time-consuming remodelling of the warp beam is necessary when changing conventional fabrics from exclusively reinforcing fibers, while the changeover of the weft system can be realized very quickly.However, it is also possible for the mixed textile to comprise a mixed fabric in which the reinforcing fibers are provided both as warp threads and as weft threads.The sustainable fibers as well as the reinforcing fibers can be realized in different ways.Some or all of the sustainable fibers may consist of recycled polyamides and / or recycled polyesters.Alternatively or additionally, some or all of the sustainable fibers may be biological fibers, for example flax, hemp, cotton or viscose fibers, or silk, jute, sisal or cocoon fibers.Alternatively or additionally, some or all of the reinforcing fibers may be in the form of glass fibers, carbon fibers, aramid fibers (p- and m-variants and combinations), poly(acrylonitrile) PAN, high-strength polyester fibers, fibers made of natural materials of inorganic origin or metal threads.Combinations of the different types of fibers are also possible.It is also possible that the reinforcing fibers and the sustainable fibers consist of a same or related polymer. For example, the reinforcing fibers may be a polyamide, e.g., an aramid, which has been directly obtained from fossil raw materials, while the sustainable fibers may be a polyamide which has been obtained from recyclate.A combination of such identical or related polymers is relevant in particular with regard to the later recycling capability of the mixed textile. Here, fabrics of the same type are clearly easier to recycle.As described, the proportion of sustainable fibers is closely related to the desired use. In many applications it will be advantageous if the proportion of the sustainable fibers is at least 10%, in particular between 25% and 75%, preferably between 33% and 67%. In this connection, a balance must always be made between a high proportion of sustainable fibers, which is desirable from an ecological point of view, and a proportion of reinforcing fibers, which is necessary from a technological point of view.In principle, all customary polymer materials can be used as matrix material, for example epoxy resins, polyurethanes, rubbers, phenacrylate resins, polyesters or polyolefins-in particular polyethylene PE and polypropylene PP.Fillers, in particular polymeric or inorganic fillers, can furthermore also be embedded in the matrix material. To further increase sustainability, some or all of these fillers may also consist of recycled material.In some applications it has proven advantageous if at least some, in particular all, after-containing fibers are present in the form of twisted yarns. In this case, it is preferably possible to use biological fibers such as hemp fibers or flax fibers, etc. as twisted yarns. These threads can be embodied in particular as pure hemp threads, flax threads or cotton threads etc.In the case of multifilaments or in the case of twisted yarns, mixed forms can also be used. Thus, it can be provided that some of the filaments in the sense of this application are embodied as "sustainable fibers" and others are embodied as reinforcing fibers. It may be advantageous to use such twisted yarns as fibers in composite materials according to aspects of the present invention.The ratio of mixed textile to matrix material can also be varied within wide ranges. Thus, for example, it can be advantageous if the weight proportion of the mixed textile amounts to between 5 wt % and 80 wt %, in particular between 5 wt % and 50 wt %, preferably between 15 wt % and 50 wt %, of the total weight of the composite material.Composite materials according to aspects of the invention can be used in the field of paper machines for various applications.A very advantageous application is the covering of rollers. In a machine for producing or processing a fibrous web, in particular a paper or pulp web, different rolls are used. Frequently, these have a roll cover which provides the contact surface with the pulp web. The composite materials described are well suited for these roll covers. The roller covers also wear during operation of the system, so that they must be renewed at regular intervals. Therefore, an increase in sustainability in these covers is very important, even because of the relatively short service life.Further advantageous applications are blades for use as doctor blade or metering blade in a machine for producing or processing a fibrous web, in particular a paper or pulp web. The described composite materials are also well suited for such blades. Here, the service lives are usually still significantly shorter than in the case of the roll covers, with the result that the advantage of the increased sustainability of the material is even more effective.Such blades are essentially two-dimensional objects which extend over the width of the installation (which may be 10 m or more) and have a height of usually 5-20 cm. The thickness of the blades, on the other hand, is only a few millimetres. The loads of such a blade in the width direction and in the height direction are very different. Therefore, an embodiment may be very advantageous in which the mixed textile is anisotropic, i.e. comprises reinforcing fibers only in one direction (e.g. width direction), or in which, for example, a mixed fabric has a different density of reinforcing fibers in the width direction of the blade than in the height direction. Here, the user is very flexible in the design of the composite material.The invention is explained below with reference to figures. The figures show in detail: Figure 1 shows a mixed textile according to an aspect of the invention FIG. 2 shows a mixed textile according to a further aspect of the invention FIG. 3 shows a mixed textile according to a further aspect of the invention Fig. 4 shows a blade according to another aspect of the invention.FIG. 1 shows a mixed textile 1, more specifically a mixed fabric 1, according to one aspect of the invention. The mixed fabric 1 consists of lasting fibers or filaments 2 and of reinforcing fibers or filaments 3. The mixed textile 1 shown in FIG. 1 is highly isotropic. Both in the warp direction K and in the weft direction S, reinforcing fibers 3 and also lasting fibers 2 are provided here.It can be provided, for example, that the reinforcing fibers 3 are present in the form of glass fibers, carbon fibers, aramid fibers (p- and m-variants and combinations) or poly(acrylonitrile) PAN, while the lasting fibers 2 consist of recycled polyamides or recycled polyesters. Other combinations are also possible.In the example shown here, every second thread oriented in the warp direction K is a lasting fiber 2, while two of three threads are lasting fibers 3 in the weft direction. For the entire mixed fabric, the proportion of the lasting fibers 2 is thus (50%+66.7%) / 2~58.3%.The mixed fabric 1 shown in FIG. 2 differs from that shown in FIG. 1 in that here the reinforcing fibers 3 are arranged only in the warp direction. A fabric 1 is thus obtained which is anisotropic in that the effect of the reinforcing fibres 3 acts only along the warp direction. In this way, the mixed fabric 1 can be adapted to the respective requirements.FIG. 3 shows, by way of example, a mixed fabric 1 in which both the yarns in the warp direction K and the yarns in the weft direction S are configured as twisted yarns 4. Specifically, the threads are designed here as mixed threads 4. These mixed threads have both lasting fibers 2 and reinforcing fibers 3. If all the mixed threads 4 are identical, a mixed fabric 4 which is substantially isotropic in its properties is obtained. Alternatively, different mixed threads 4 can also be used in one fabric, for example threads 4 with different proportions of lasting fibers 2. Alternatively, some of the mixed threads 4 can also be replaced by purely sustainable or purely reinforcing threads or filaments.The mixed fabrics 1 described in FIGS. 1 to 3 can provide the reinforcing structure for a composite material according to aspects of the invention alone or together with further textile layers.Finally, FIG. 4 shows, by way of example, a blade 10, for example a metering blade 10 made of a composite material according to one aspect of the invention. A mixed textile 4, for example a mixed scrim 4 or mixed fabric 4, is embedded in a matrix material 5. The mixed textile can be, for example, a mixed textile 4, as described in FIGS. 1 to 3. The matrix material 5 can be, for example, an epoxy resin, a polyester or a polyolefin. Fillers, in particular polymeric or inorganic fillers, can furthermore also be embedded in the matrix material 5.List of reference characters1 Mixed textile 2 Lasting fiber / lasting filament 3 Reinforcing fiber / reinforcing filament 4 Mixed twist 5 Matrix material 6 Reinforcing structure 10 Blade K Warp direction S Weft directionReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedEP 4 108 828

[0005] WO 2021 / 074492 A1

[0006]

Claims

Composite material comprising a matrix material (5) and a reinforcing structure (6) which is embedded in the matrix material (5), characterized in that the reinforcing structure (6) comprises or consists of a mixed textile (1), wherein the mixed textile (1) comprises both sustainable fibers (2) and reinforcing fibers (3).Composite material according to one of the preceding claims, characterized in that the mixed textile (1) consists of one or more textile layers, and in particular comprises or consists of a mixed fabric (1) or a mixed laid scrim.Composite material according to claim 2, characterised in that the mixed textile (1) comprises or consists of a mixed fabric (1), wherein the reinforcing fibres (2) are provided only as warp threads or only as weft threads.Composite material according to claim 2, characterised in that the mixed textile (1) comprises a mixed fabric (1), wherein the reinforcing fibres (3) are provided both as warp threads and as weft threads.Composite material according to one of the preceding claims, characterized in that the mixed textile (1) comprises sustainable fibres (2) made of recycled polyamides or recycled polyesters.Composite material according to one of the preceding claims, characterized in that the mixed textile (1) comprises sustainable fibres (2) in the form of biological fibres, in particular flax, hemp, cotton or viscose fibres.Composite material according to one of the preceding claims, characterized in that the mixed textile (1) comprises reinforcing fibers (3) in the form of glass fibers, carbon fibers, aramid fibers (p- and m-variants and combinations) or poly(acrylonitrile) PAN, high-strength polyester fibers, fibers made of natural materials of inorganic origin or metal threads.Composite material according to one of the preceding claims, characterized in that the proportion of the sustainable fibres (2) is at least 10%, in particular between 25% and 75%, preferably between 33% and 67%.Composite material according to one of the preceding claims, characterized in that the matrix material (5) comprises or consists of an epoxy resin, a polyurethane, a rubber, a phenacrylate resin, a polyester or a polyolefin.Composite material according to one of the preceding claims, characterized in that fillers, in particular polymeric or inorganic fillers, are also embedded in the matrix material (5).Composite material according to Claim 10, characterized in that the fillers consist wholly or partly of recycled material.Composite material according to one of the preceding claims, characterized in that at least some, in particular all, sustainable fibres (2) are present in the form of twisted yarns (4).Composite material according to one of the preceding claims, characterized in that the proportion by weight of the mixed textile (1) makes up between 5% by weight and 80% by weight, in particular between 5% by weight and 50% by weight, preferably between 15% by weight and 50% by weight, of the total weight of the composite material.Roll for a machine for producing or processing a fibrous web, in particular a paper or cellulose web, wherein the roll has a roll cover which provides the contact surface with the cellulose web, characterized in that the roll cover consists wholly or partly of a composite material according to one of the preceding claims.Blade (10) for use as a doctor blade or metering blade in a machine for producing or processing a fibrous web, in particular a paper or pulp web, characterized in that the blade consists wholly or partly of a composite material according to one of Claims 1 to 13.

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