EP3147393A1 - Textile reinforcement using yarn and method for preparing a yarn - Google Patents

Abstract

The invention relates to a method for preparing a yarn, in particular a multifilament yarn, for use as a textile reinforcement in a matrix material, in particular a mineral matrix material, a textile reinforcement and a component comprising this reinforcement. The object of the invention is to improve the wettability of multifilament yarns, especially for aqueous mineral coatings. To solve the surface of the yarn is modified by means of a plasma-chemical and / or plasma-physical process in such a way that at least the wettability is improved by the resulting modification.

Description

The invention relates to a textile reinforcement by means of yarn, so that a component comprising a matrix material and the reinforcement is formed. An aqueous, mineral matrix material, for example concrete, is also suitable as the matrix material. The invention furthermore relates to a method for preparing a yarn, in particular multifilament yarn, which can be used as textile reinforcement, in particular in an aqueous, mineral matrix material.

The building material concrete is very well suited for absorbing pressure loads. However, it has only a low absorption capacity in terms of tensile stress and shows a pronounced brittle material failure. Therefore, concrete components for receiving tensile stresses, for example resulting from bending moments or from forced stresses (eg shrinkage, temperature), require reinforcement. The combination of concrete and tension-absorbing reinforcement creates a high-performance building material. In this case, the reinforcement can be installed in various geometric arrangements, with lattice-shaped structures or bars generally being used. Structural steel has hitherto been used as the material, which must be protected against corrosion depending on existing exposures with concrete coverages of up to 5.5 cm. To reduce concrete coverages, corrosion-resistant materials such as carbon or alkali-resistant glass (AR glass) have been researched for several years, and reinforcements made from these materials are being prepared for a wide practical application. A first step was achieved with the composite material textile concrete.

Textile concrete or textile-reinforced concrete is a composite material made of concrete and a textile fabric (scrim). The textile fabric used as reinforcement preferably consists of multifilament yarns, the materials used being AR glass, carbon and / or basalt. The individual multifilament yarns, referred to below as roving, are composed of several thousand filaments. The filament diameters are in a range between about 7 μm (carbon) and 20 μm (AR glass). If you were to place the rovings uncoated in the concrete, only the outer filaments of the rovings would connect with the concrete. The inner filaments have no regular connection to the concrete matrix. Thus, primarily only the outer filaments will participate in the load transfer and the potential carrying capacity of the yarns will not be exploited.

For the desired participation of all filaments in the load transfer of the roving or the textile is provided with a polymer coating with respect to the filaments or an impregnation of the entire roving, which infiltrates into the structure. The coating materials used today are predominantly styrene butadiene and epoxy resin. The composite behavior between the inner filaments of the yarns is improved, and thus the load-bearing reserves of the yarn material are utilized to a greater extent. At the same time, the bond between yarn and surrounding fine concrete is increased. The load-bearing capacity of the coated structures is thus significantly higher than that of uncoated rovings or textiles. In the same way, the load transfer takes place even with rod-shaped reinforcements made of fiber-reinforced plastic.

The typically used reinforcing materials, such as carbon, and also the concrete as the matrix material are significantly more temperature resistant and durable than the plastic coating that wraps and bonds the reinforcing material to each other and to the matrix material. The coating, which is decisive as a boundary layer, in particular for the decisive bond to the surrounding matrix of the component, therefore essentially determines the temperature or fire behavior, the creep behavior and the time-dependent deformation behavior of textile concrete under load (creep). Therefore, the properties of the coating material is of great importance.

In addition to the many advantages in terms of manufacturing technology and use, the current reinforcements, similar to fiber-reinforced plastics, have a coating or a bonding matrix in flat or rod-shaped form, which, however, is neither very temperature-resistant nor durable. The problem of the plastics used so far is that they are usually very susceptible to temperature, depending on the system used. From temperatures between 40 ° C and 120 ° C, the positive effect of the coating decreases. Softening significantly reduces their function. When proving a component for a fire, a temperature resistance of the coating of up to 600 ° C is usually required. Furthermore, a continuous loading of the plastics can lead to pronounced creep of the coating and thus to the unwanted, very significant increase in the deformation of the composite component. The durability given to plastics for a limited time can lead to embrittlement and / or aging, in particular due to the alkaline environment in the concrete.

The polymer dispersions used to increase the utilization of the theoretical yarn strength can be applied to the yarn structures relatively favorably in terms of production technology and are also able to more easily infiltrate the structures. By modification and adaptation of the polymers, the properties of the coated reinforcement structures can be adjusted specifically to the requirements of the handling. This concerns for example the deformability. The polymers are usually applied in the form of dispersions on coating rollers on flat textile structures and thermally dried by infrared radiation and crosslinked. Rod-shaped fiber reinforcements are made by pultruding with suitable systems of thermoplastic or thermosetting resins. Such a method describes by way of example the document US 4,728,387 A. ,

While the polymers used in the prior art allow a good coating of rovings, this is not the case for alternative materials that are very temperature resistant and durable and also in the alkaline environment in the concrete to embrittlement or aging. Suitable coating materials with regard to their properties in the concrete are, for example, aqueous suspensions of mineral inorganic binders.

It would thus be useful to develop a method that can be dispensed with the polymeric plastic coating and the binding of the individual filaments by temperature-resistant matrices, for example on a mineral basis occurs. This is of great importance, above all, for ensuring the high-temperature behavior (fire resistance). If this multifilament yarns are guided in a compact form by a mineral binder suspension, due to the particle size of the binder components infiltration takes place only in the outer region of the yarn, so that the inner filaments remain unwetted. A solution attempt is with the publication US Pat. No. 6,174,559 B1 offered with a stainless sheathing of rods, pipes or pipes to be achieved and also as a mineral matrix material cement provides (see Sp 8, Z. 63). It does not depend on static aspects, but on the tightness of the envelope. However, the filament bundles are twisted or wrapped again transversely to the main fiber direction. Both would destroy carbon fibers in view of the low strength transverse to the longitudinal direction. There are therefore doubts about the feasibility, as far as the Revelation on mineral matrix material or on carbon fibers (see Sp. 14, Z. 14 - 17) turns off. However, how to achieve a secure connection between the fibers and the surrounding matrix, which is important for static applications, is not explained, but only asserted (compare Sp 8, Z 38-39, Sp 10, Z 16-17). , In fact, there will be unresolved problems in achieving adequate wetting of the fibers with the matrix material if an aqueous mineral matrix or coating material is to be used.

A technological problem with the aforementioned approach is therefore that the uncoated fiber surfaces of multifilament yarns (eg carbon) are not affine towards the aqueous suspensions of mineral inorganic binders. The known solutions for application of the polymeric coatings can therefore not be transferred in particular to aqueous mineral coatings and matrix systems without adjustments and / or extensions of the technology. Due to the low affinity properties of the multifilament yarns compared to the suspensions, only an insufficient coating and / or embedding in the mineral matrix is achieved. Due to the reduced composite, the carrying reserves of the fiber structures are only insufficiently utilized.

The object of the invention is therefore to improve the wettability of multifilament yarns in a simple and cost-effective manner, especially for aqueous mineral coatings, so that additional mineral or metallic layers can be applied to the fiber surface. A method or a method is to be made available with which the fiber surface of reinforcing structures can be designed affine or more hydrophilic compared to aqueous suspensions of mineral, inorganic binder matrices. Furthermore, a textile reinforcement with improved wettability and a reinforced component to be offered.

The object of the invention is achieved by a method according to claim 1. Advantageous embodiments are specified in the subclaims.

Although plasma-chemical or plasma-physical processes are known per se from the prior art:

Käppler, Iris; Dog, Rolf-Dieter, Cherif, Chokri: Surface modification of carbon fibers using plasma technique. Autex Research Journal, Vol. 14, No. 1, pp. 34-38, ISSN (Print) 1470-9589, 001: 10.2478 / v10304-012-0048-y, March 2014 ,
Here, however, only the surface properties are manipulated by means of plasma with the aim of better wettability of the filaments for gluing the yarns, which is to serve as a replacement for the textile-technical binding.

Lee, Seung-Wook; Lee, Hwa Young; Jang, Sung-Yeon; Jo, Seong Mu; Lee Hun-Soo; and Le, Sungho: Tensile Properties and Morphology of Carbon Fibers Stabilized by Plasma Treatment. Carbon Letters, Vol. 12, no. 1 March 2011, pp. 16-20 ,
In this case, however, the plasma treatment only serves to modify the production process of a fiber. By aftertreatment with plasma while the mechanical properties are to be improved.

• die Faseroberfläche von Multifilamentgarnen affiner/hydrophiler gegenüber den wässrigen Suspensionen von mineralischen anorganischen Bindemittelmatrices gestaltet werden kann,
• auf der Faseroberfläche von Multifilamentgarnen zusätzliche mineralische Schichten (beispielsweise Keramik) zur Steigerung des Verbundes aufgetragen werden können,
• auf der Faseroberfläche von Multifilamentgarnen zusätzliche elektrisch leitfähige Schichten zur Kontaktierung aufgetragen werden können (beispielsweise für Heizgelege, Sensorik etc.).

Surprisingly, after the adaptation according to the invention and application of such processes to yarns, in particular multifilament yarns, for use as textile reinforcement, it has been found that improved bonding of the fibers to the coating or to the surrounding (in particular mineral) matrix is achieved by pretreatment of the fibers Surface to the result, could be achieved. The approach of the present invention is to provide methods and methods known per se on the basis of plasma-chemical and -physical processes and to modify them so that with them:

• the fiber surface of multifilament yarns can be made more affine / hydrophilic than the aqueous suspensions of mineral inorganic binder matrices,
• on the fiber surface of multifilament yarns additional mineral layers (for example ceramic) can be applied to increase the bond,
• on the fiber surface of multifilament yarns additional electrically conductive layers can be applied for contacting (for example, for Heizgelege, sensors, etc.).

Due to the improved wettability of the filaments or the application of mineral layers, the bonding behavior or the load transfer of reinforcement structures made of multifilament yarns can generally be decisively increased.

A promising positive effect with regard to increasing the bonding behavior was found in the plasma treatment of carbonic anhydrides for surface modification (hydrophilization), which were subsequently embedded in mineral matrices. For the technological implementation, it has proven to be particularly advantageous that light crystalline structures can be formed on the fiber surface and between the filaments in the fiber bundle.

To improve the composite properties, additional measures can be carried out, for example by profiling the yarns or structures. These can be carried out by a local application with resin systems, which in turn behave problematic in terms of higher temperatures and / or fire.

The object of the invention is further achieved by a plasma-chemical process. In this case, a specific modification of the fiber surface (for example, carbon, AR glass, basalt) for a subsequent order with a further substance, here for example in the form of an aqueous suspension with mineral fines carried out. In the context of the plasma-based modification, an interaction of the plasma with the fiber surfaces or with the production-technologically applied fiber size takes place. Depending on the selected process parameters (composition of the process gases, process time, excitation frequency and power, pressure and gas flow rate), the surface energy can be selectively adjusted by the interaction plasma surface in the form of changes of the molecular structures on the surface and the associated increase in the polar binding fraction , which leads to an improvement of wettability or reactivity with the coating / impregnation material.

In addition to the mentioned aqueous mineral suspension, other types of coating / matrix materials are conceivable by adapting the process conditions and the technological boundary conditions. Such boundary conditions are especially process parameters, such as composition of process gases, process time, excitation frequency and power, pressure and gas flow rate.

The approach to the activation of fiber surfaces can thus be transferred to other matrix systems, such as polymer dispersions or various resin systems in addition to mineral-based systems such as reinforced concrete.

Furthermore, the composite behavior of the reinforcement structures can be improved by the deposition of ceramic layers. The process of applying a layer is based on plasma-chemical processes (PECVD), in which a precursor corresponding to the ceramic material, e.g. HMDSO (hexamethyldisiloxane) or TEOS (tetraethyl orthosilicate) is used. The job can be done in sections or locally limited (for example, nodes), so that the advantage of flexibility of the reinforcement structures of multifilament yarns is maintained.

Electrically conductive contacts of carbon structures (Heizgelegen) are, so far known, previously produced by pressing metallic sleeves or bands. By applying metallic layers, which is done by means of PVD process, electrically conductive yarns (carbon) can be permanently contacted. The PVD process is based on the sputtering of conductive material, which is condensed on the yarn structure during the coating process and thus deposited there. The sputtering process is magnetron sputtering with argon as working gas.

The essence of the invention lies above all in the possibility of plasma technology for modifying the surface properties of materials, which in itself has been known for several decades. The practical and commercial application for industrial problem solutions has increased significantly over time. The fields of application are very different. In addition to the surface modification for joining various materials, the surface modification (inter alia by means of layer application) also plays an important role in improving the performance characteristics, for example scratch protection, mirroring, printability, barrier protection, etc. In contrast, the use of plasma technology for the modification of fiber surfaces in multifilament yarns with the aim of better wettability (hydrophilization) with aqueous mineral suspensions despite the long knownness of the underlying technology is not known and represents the essence of the present invention with its surprising effect.

The ultimate goal for the primary application is to increase the bond properties between the individual filaments and the mineral matrix both within the yarns and outside of the surrounding mineral matrix in cementitious components. Instead of the mineral matrix, other matrix systems are also conceivable.

Another novelty is the order of mineral layers (ceramics) using PECVD processes on (carbon) reinforcement structures. Plasma-enhanced chemical vapor deposition (PECVD) is a special form of chemical vapor deposition (CVD) in which chemical deposition is assisted by a plasma. The plasma can burn directly on the substrate to be coated (direct plasma method) or in a separate chamber (remote plasma method).

The order can be made over the entire surface or gradually. The gradual or sectional application allows a metered introduction of the composite forces in order to control the load-deformation behavior and failure behavior of the material according to the respective requirements.

Similarly, end anchorages of prestressed reinforcement structures (for example carbon, AR glass, basalt) can be produced by the application of ceramic layers. In carbon, these have the additional advantage of reducing the transverse pressure sensitivity for gripping the reinforcements.

The electrical contacting of carbon by applying metals allows a low-resistance and durable connection.

The object of the invention is also achieved by a textile reinforcement according to claim 8 and such a reinforced component according to claim 13.

• bessere Benetzbarkeit der Filamentoberflächen von Multifilamentgarnen mit wässrigen mineralischen Suspensionen (Hydrophilierung);
• keine chemische Behandlung zur Aktivierung der Faseroberflächen erforderlich;
• Anwendbarkeit in einem großtechnischen Herstellungsprozess;
• eine zusätzliche Kunststoffbeschichtung zwischen Beton und Garnen oder Filamenten ist nicht notwendig;
• die Bewehrungsstrukturen sind damit temperaturbeständiger und dauerhafter als bisherige Lösungen;
• durch vollständiges oder graduelles Auftragen keramischer Schichten kann das Verbundverhalten gesteuert werden;
• eine gradueller Schichtauftrag ermöglicht den Erhalt der Flexibilität der Bewehrung beim Handling;
• durch Abscheidung metallischer Schichten können Carbonstrukturen leitfähig kontaktiert werden (beispielsweise Heizmatten);
• die Bewehrungsstrukturen besitzen einen hervorragenden Verbund zum später umgebenden Beton (chemisch kompatible Matrices von Bewehrung und Beton).

Key benefits include:

• better wettability of the filament surfaces of multifilament yarns with aqueous mineral suspensions (hydrophilization);
• no chemical treatment required to activate fiber surfaces;
• Applicability in a large-scale manufacturing process;
• an additional plastic coating between concrete and yarns or filaments is not necessary;
• The reinforcement structures are thus more temperature-resistant and more durable than previous solutions;
• By complete or gradual application of ceramic layers, the bonding behavior can be controlled;
• a gradual layer application allows maintaining the flexibility of the reinforcement during handling;
• by depositing metallic layers, carbon structures can be conductively contacted (for example, heating mats);
• the reinforcing structures have an excellent bond to the surrounding concrete (chemically compatible matrices of reinforcement and concrete).

Due to the improved wettability of the individual filaments, the bonding behavior and the load transfer of the final reinforcement structure are significantly increased. This makes it possible to achieve a high utilization of the load-bearing reserves of the yarn structures when embedded in mineral matrix systems, in particular with regard to the behavior of composite components (eg of textile-reinforced concrete) at elevated temperatures (including fire stress). As reinforcing structures, both bars and lattice-shaped structures are provided.

Further details, features and advantages of the invention will become apparent from the following description of exemplary embodiments with reference to the accompanying drawings.

Fig. 1 schematically shows an embodiment of a reinforcement according to the invention comprising a yarn 1 and a detail of the yarn 1, in particular a multifilament yarn. The multifilament yarns or rovings form a scrim. The treatment according to the invention of the roving takes place only as a partial modification 2 in order to allow the application of mineral layers, here a ceramic as an additional mineral layer 3, at the nodal points of the layer.

Fig. 2 schematically shows an embodiment of a yarn 1 according to the invention, which has the modification 2 instead of a full-surface modification 2, ie treatment of the surface or order of a further material, also in sections or only at the end. It is of importance how the forces are transferred to the matrix material, especially while avoiding tearing out of matrix material by overload. The treatment in the end area provides for an improved final anchorage 4. Shown is the coating order of a ceramic as an additional mineral layer 3.

Claims (14)

Method for preparing a yarn, in particular a multifilament yarn, for use as textile reinforcement in a matrix material, in particular a mineral matrix material, characterized in that the surface of the yarn (1) is modified by means of a plasma-chemical and / or plasma-physical process in such a way that at least the wettability is improved by the resulting modification (2). The method of claim 1, wherein the fiber surface of the yarn (1) is affine and / or hydrophilic to aqueous suspensions of mineral inorganic binder matrices designed by a surface chemistry of the filaments in the yarn is influenced by a plasma-chemical and / or plasma physical process, that improved Penetration of an aqueous mineral coating within the yarn (1) and thus a secure connection to a mineral matrix material is possible. A method according to claim 1, wherein the fiber surface of the yarn (1) is made more affine and / or hydrophilic to polymer dispersions or resin systems by influencing the surface energy of the filaments in the yarn (1) by a plasma-chemical and / or plasma-physical process Penetration of polymer dispersions or resin systems takes place within the yarn and thus a secure connection to the matrix material is possible. The method of claim 1, wherein the fiber surface of the yarn (1) is prepared so that all over or gradually at least one additional mineral layer (3) can be applied to increase the bond with the coating and / or the matrix material, wherein the order by the PECVD method is carried out and a mineral material corresponding precursor is used. A method according to claim 4, wherein a ceramic is provided as an additional mineral layer (3). The method of claim 5, wherein as a precursor HMDSO or TEOS are provided. Method according to claim 1, wherein the fiber surface of the yarn (1) is prepared such that at least one additional electrically conductive layer suitable for electrical contacting can be applied to the fiber surface of the yarn (1), in that the deposition of metallic layers takes place by means of the PVD method, wherein the sputtering process is provided by magnetron sputtering with argon as the working gas. A textile reinforcement comprising a yarn, in particular multifilament yarn, characterized in that the multifilament yarn comprises filaments treated by a process according to any one of claims 1 to 7. Reinforcement according to claim 8, wherein at least one additional mineral layer (3) for increasing the bond with the coating and / or the matrix material is applied to the fiber surface of the yarn (1). Reinforcement according to claim 9, wherein a ceramic is provided as additional mineral layer (3). Reinforcement according to one of claims 8 to 10, wherein on the fiber surface of the yarn (1) at least one additional electrically conductive layer (3), suitable for electrical contacting, is applied. Reinforcement according to claim 11, wherein the reinforcement (1) serving as reinforcement is additionally used as an electrically active component of a heating system or a sensor arrangement. Component comprising a matrix material and a yarn, in particular multifilament yarn, as a reinforcement, characterized in that the reinforcement comprises a yarn (1) according to one of claims 8 to 12. Component according to claim 13, wherein the component is designed as a concrete component comprising concrete as matrix material.

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