EP2563959A1

EP2563959A1 - Hybrid yarn for producing molded parts

Info

Publication number: EP2563959A1
Application number: EP11719783A
Authority: EP
Inventors: Uwe Heitmann; Heinrich Planck
Original assignee: Deutsche Institute fuer Textil und Faserforschung Stuttgart
Current assignee: Deutsche Institute fuer Textil und Faserforschung Stuttgart
Priority date: 2010-04-30
Filing date: 2011-04-27
Publication date: 2013-03-06
Also published as: WO2011134995A1; US8950168B2; CN103025938A; BR112012026824A2; AU2011247675A1; CA2796747A1; KR20130096642A; IL222475A0; US20130104515A1; JP2013531138A; DE102010028433A1; RU2012151217A; MX2012012510A

Abstract

The invention relates to a hybrid yarn (1) for producing molded parts (8) which have a thermoplastic matrix and reinforcing fibers (4, 5, 6, 7) embedded therein. The hybrid yarn (1) comprises a core (2) that substantially consists of staple fibers (4, 5) oriented in a linear manner in a longitudinal direction (LR) of the hybrid yarn (1) and a jacket (3) that substantially consists of staple fibers (6, 7) looped around the core (2) in a helical line-shaped manner. The staple fibers (4, 5) that form the core (2) and the staple fibers (6, 7) that form the jacket (3) each consists of an intimate mixture (4, 5; 6, 7) of thermoplastic matrix fibers (4, 6) and reinforcing fibers (5, 7).

Description

Hvbridqarn for the production of molded parts

The present invention relates to a hybrid yarn for producing molded articles comprising a thermoplastic matrix and reinforcing fibers embedded therein.

Under a yarn is generally understood a strand-like fiber structure whose fibers are solidified by twisting. A hybrid yarn is one such yarn comprising at least two different types of fibers. Among others, special hybrid yarns are known, which are suitable for the production of molded parts with a thermoplastic matrix and with embedded reinforcing fibers. In this case, a shaped part is understood to mean a workpiece which, after its completion, remains in a structural shape predetermined by the manufacturing process.

In a known method for producing such shaped parts, a hybrid yarn which contains both thermoplastic matrix fibers and reinforcing fibers is first processed into a textile fabric. The reinforcing fibers have a higher specific tensile strength and a higher melting or decomposition temperature than the thermoplastic matrix fibers. This textile fabric is then placed in a mold, such as a press, and heated, so that the thermoplastic matrix fibers, but not the reinforcing fibers, melt. As a result, initially a uniform thermoplastic liquid with embedded reinforcing fibers, which assumes the shape predefined by the molding tool, arises from the originally discrete thermoplastic matrix fibers. After cooling and solidification, the now consolidated thermoplastic matrix fibers form a uniform thermoplastic matrix in which the reinforcing fibers are embedded. As a result of the mutual interactions of the thermoplastic matrix and the reinforcing fibers, a molded part is produced whose mechanical properties are superior to the properties of the two components. In particular, there is a particularly good ratio of strength and weight. Nevertheless, there is a need for further improved moldings.

The object of the present invention is to provide a hybrid yarn which enables the production of improved molded articles with a thermoplastic matrix and with reinforcing fibers embedded therein.

The object is achieved with a hybrid yarn of the type mentioned at the outset in that it comprises a core consisting essentially of staple fibers arranged in a straight line in a longitudinal direction of the hybrid yarn and a jacket consisting essentially of staple fibers wound around the core in a helical manner, wherein the staple fibers forming the core and the staple fibers forming the sheath each consist of an intimate mixture of thermoplastic matrix fibers and reinforcing fibers.

The hybrid yarn according to the invention comprises a core and a jacket arranged around the core. Both the core and the sheath consist at least essentially of staple fibers. By staple fibers are meant single fibers which are limited in their length. The sheath can have such a high number of staple fibers per unit length that the sheath forms a closed layer through which the staple fibers of the core are completely covered. However, such a small number of staple fibers per unit length can be provided in the jacket that the staple fibers of the core remain at least partially visible through spaces between the staple fibers of the jacket. Formed from hybrid fibers containing staple fibers have higher strength transverse to the longitudinal direction of the yarns, as such moldings, which are made of continuous fibers, also called filaments, existing hybrid yarns. In particular, the cohesion of the individual layers can thus be improved in the case of molded parts which are produced from textile fabrics arranged in layers.

In addition, hybrid yarns with staple fibers have a smaller void fraction than hybrid yarns with continuous fibers, which reduces the risk of undesired air pockets during molding of the molded article, ie when consolidating the textile fabric. In this way, the strength of the molded part is improved.

Furthermore, textile fabrics made from staple fiber-containing hybrid yarns are more drapeable than their filament counterparts. This facilitates the wrinkle-free insertion of the textile fabric into the mold, at the same time reducing the risk of damage to the structure of the textile fabric. In this way, the manufacturing cost of the molding can be reduced. In addition, more complex shaped molded parts can be produced from textile fabrics, since the textile fabrics can be better applied to the contour of the molding tool.

Furthermore, the risk is reduced by the use of staple fibers, that the fibers in the further processing, in particular during draping, are kinked. This in turn is advantageous for the strength of the later molded part.

By now both the core and the sheath of the hybrid yarn consists of staple fibers, the above-mentioned advantages that can be achieved by using staple fibers can be maximally utilized. Furthermore, the linear arrangement of the staple fibers of the core in the longitudinal direction of the hybrid yarn causes the later molded part in the longitudinal direction of the hybrid yarn, a higher strength, in particular a higher tensile strength, than when using conventional hybrid yarns, in which the fibers over the entire cross section twisted, would be possible. The reason for this is that in the molded part, a substantial proportion of the reinforcing fibers, namely the reinforcing fibers of the core of the hybrid yarn, runs parallel to one another in the longitudinal direction of the hybrid yarn.

Now, if the hybrid yarn is arranged in the textile fabric so that its longitudinal direction at least partially corresponds to a main load direction of the subsequent molded part, the molded part can better withstand mechanical stresses. In this way, the ratio of mechanical strength and weight of the molded part can be improved.

Although hybrid yarn according to the invention under certain conditions (rotation coefficient, yarn count, etc.) may have a lower strength than a corresponding hybrid yarn, in which the fibers are uniformly twisted over the entire cross section, but this is secondary, since the strength of the molded part inter alia the consolidation of the thermoplastic matrix fibers is increased and therefore substantially independent of the strength of the hybrid yarn. However, the strength of the hybrid yarn must be at least so high that a further processing to a textile fabric and on to a molded part is possible. This necessary strength is ensured in the case of the hybrid yarn according to the invention in that the staple fibers forming the sheath are wound helically around the core and consequently twisted. The reinforcing fibers contained in the sheath thereby improve the strength of the later molded part transversely to the longitudinal direction of the hybrid yarn raised therein, in comparison with those shaped parts which are manufactured from hybrid fibers consisting of continuous fibers. As a result, the cohesion of the individual layers can be further improved in the case of molded parts which are produced from textile fabrics arranged in layers.

The staple fibers forming the core, like the staple fibers forming the sheath, each consist of an intimate mixture of thermoplastic matrix fibers and reinforcing fibers. An intimate mixture of fibers of different types is understood here as meaning a mixture in which a substantially homogeneous mixture is present at the level of the individual fibers. This means that the fibers of the various types are mixed so that groupings of exclusively identical fibers essentially no longer occur. The intimate mixture or the intimate mixtures can be done even before the actual formation of the hybrid yarn. In this case, the use of staple fibers facilitates the production of uniform mixtures, which can be produced, for example, with a spinning preparation machine, for example with a mixing machine or a doubling section.

The use of intimate mixtures ensures that the thermoplastic matrix fibers and the reinforcing fibers are homogeneously distributed in the textile fabric produced from the hybrid yarn. In this way it can be achieved that the reinforcing fibers are completely wetted during melting of the thermoplastic matrix fibers, so that the interactions between the thermoplastic matrix and the reinforcing fibers are maximized in the later molding by an improved cohesive connection, so that a mechanically highly resilient molding with low Weight is created. According to an advantageous development of the invention, the volume-related proportion of the reinforcing fibers in a said intimate mixture is at least 40%, preferably at least 45%, particularly preferably at least 50%. This makes it possible to produce a molded part with particularly high strength from the hybrid yarn.

According to an advantageous development of the invention, the volume-related proportion of the thermoplastic matrix fibers in a said intimate mixture is at least 20%, preferably at least 30%, particularly preferably at least 35%. In this way it can be ensured that the reinforcing fibers are in each case completely surrounded by the thermoplastic matrix after consolidation of the thermoplastic matrix fibers, which improves the cohesive connection of thermoplastic matrix and reinforcing fibers and thus benefits the mechanical properties of the molded part.

According to an expedient development of the invention, the staple fibers forming the core and the staple fibers forming the sheath correspond in terms of their said intimate mixture. This means that, on the one hand, the proportion of the thermoplastic matrix fibers at the core is equal to the proportion of the thermoplastic matrix fibers in the sheath, and, on the other hand, the proportion of the reinforcing fibers at the core is equal to the proportion of the reinforcing fibers in the sheath. In addition, the thermoplastic matrix fibers in the core and the cladding correspond in terms of their material and their dimensions as well as the reinforcing fibers in the core and the cladding. In this way, the production of moldings is simplified, since so the core and the shell of a starting mixture can be produced. In addition, as a homogeneous formation of the thermoplastic matrix can be guaranteed in the later molding, which benefits its mechanical properties. According to an expedient development of the invention, the sum of the volume-related proportion of the thermoplastic matrix fibers and the volume-related proportion of the reinforcing fibers on the hybrid yarn is at least 90%, preferably at least 95%, particularly preferably at least 98%. In this way, molded parts can be produced with a particularly good strength and low weight. The remaining volume fractions can be attributed, for example, to a size or adhesion promoter. In this context, a size is understood to mean a typically viscous coating which protects the hybrid yarn, in particular during further processing into a textile fabric, against mechanical effects. Furthermore, an adhesion promoter is understood to mean a coating which improves the cohesive connection between matrix and reinforcing fibers which is produced during the melting and cooling of the thermoplastic matrix.

According to an advantageous embodiment of the invention, the staple fibers forming the core and / or the staple fibers forming the sheath have a length of at least 2.5 cm, preferably of at least 5 cm, more preferably of at least 10 cm and / or a length of at most 25 cm , preferably of at most 20 cm, more preferably of at most 15 cm, on. Such staple lengths lead to particularly solid moldings. In addition, such staple fibers can be produced and processed using conventional machines.

According to an expedient development of the invention, the thermoplastic matrix fibers have a fineness-related maximum tensile force of at least 20 cN / tex, preferably of at least 30 cN / tex, more preferably of at least 50 cN / tex. The maximum tensile force is that tensile force at which a fiber just barely ruptures. In this way it can be ensured that the matrix whose specific maximum tensile force corresponds to the fineness-related maximum tensile force of the thermoplastic fibers, in particular in the finished molded part, transversely to adjacent reinforcing elements. fibers can absorb mechanical stresses occurring, which further improves the load capacity of the molded part.

According to an expedient development of the invention, the thermoplastic matrix fibers comprise polyurethane fibers (in particular fibers of PU), polyamide fibers (in particular fibers of PA), polyether ketone fibers (in particular fibers of PAEK and of its derivatives, in particular PEEK, PEK, PEEEK, PEEKEK, PEKK), polypropylene fibers (in particular PP fibers), acrylonitrile-butadiene-styrene fibers (in particular ABS fibers) and / or polyester fibers (in particular fibers from PES and from its derivatives, in particular PBT, PC, PET, PEN). Such materials meet in particular the requirements in terms of their strength, are inexpensive and easy to process.

According to an advantageous development of the invention, the thermoplastic matrix fibers consist of a single material. In this way, in the finished molding in a simple manner, a homogeneous thermoplastic matrix, which improves its mechanical properties.

According to an expedient development of the invention, the reinforcing fibers have a fineness-related maximum tensile force of at least 100 cN / tex, preferably of at least 150 cN / tex, more preferably of at least 200 cN / tex. In this way, the molded part produced therefrom can absorb particularly high mechanical loads, in particular in the fiber direction.

According to an expedient development of the invention, the reinforcing fibers comprise glass fibers, carbon fibers and / or aramid fibers. Such materials meet the requirements of reinforcing fibers in particular with regard to their strength, are still inexpensive and easy to process. But there are also other high modulus fibers possible According to an advantageous embodiment of the invention, the reinforcing fibers consist of a single material. In this way, the properties of a material suitable for reinforcing fibers can be utilized to the greatest extent possible.

According to an expedient development of the invention, the rotation coefficient a _{m of} the hybrid yarn is at most 200, preferably at most 170, particularly preferably at most 150, and / or at least 70, preferably at least 90, particularly preferably at least 1 10. The coefficient of rotation cim is given by the formula a _m = T / Nm ^1/2 where T is the number of turns per meter of yarn length and Nm ^{/ 2 is} the root of the metric yarn count. In the stated ranges, the hybrid yarn generally has good strength, which makes it possible to keep the proportion of staple fibers in the sheath based on the total staple fibers low. Conversely, so the proportion of staple fibers in the core can be increased based on the total staple fibers, which is the strength of the subsequent molding useful.

According to an expedient development of the invention, the hybrid yarn has a total titer of at least 100 dtex, preferably of at least 150 dtex, more preferably of at least 200 dtex, and / or of at most 15000 dtex, preferably of at most 12000 dtex, more preferably of at most 10000 dtex, on. Hybrid yarns having a total titer in the ranges mentioned are particularly suitable for the production of textile fabrics. So they usually have the required strength for further processing. Nevertheless, it is also possible to produce thin-walled molded parts from the textile fabrics obtained therefrom. If thicker-walled molded parts are to be produced, then several of the textile fabrics thus obtained can be arranged in layers and in particular be consolidated together. Hybrid yarns with such a total titre can also be processed on common textile machines.

According to an advantageous embodiment of the invention, the proportion of the staple fibers forming the sheath on the staple fibers is at least 2%, preferably at least 5%, more preferably at least 15% and / or at most 45%, preferably at most 35%, particularly preferably at most 25%. In the genanten ranges, the hybrid yarn generally has a sufficient strength for further processing, at the same time it has a high proportion of staple fibers and thus a high proportion of reinforcing fibers in the core, so that particularly stable moldings can be produced.

According to an expedient development of the invention, the Kringelneigung is at most 200 1 / m, preferably at most 180 1 / m, more preferably at most 160 1 / m. The curl tendency is the tendency of a yarn, caused by its rotation, to twist together when it is suspended in a loop freely between two points. To measure the tendency to curl, yarn sections of, for example, 500 mm in length can be used, whose yarn ends are clamped so that the yarn section is arranged horizontally. A weight can then be hung in the middle and the yarn ends moved towards one another. The weight starts to rotate and the rotations can be counted by means of a light barrier until the direction of rotation reverses. The values of 10 measurements are evaluated and output as a measured value. Hybrid yarns with the mentioned values of the tendency to curl can be processed particularly well. In particular, textile fabrics produced therefrom can be inserted into a mold in a simple and wrinkle-free manner. According to a particularly advantageous embodiment of the invention, the hybrid yarn is produced by means of an air-spinning process. In an air spinning process, a substantially untwisted sliver is stretched to the desired fineness and passed through an air stream which gives the drawn sliver a false twist. Here, the outer fibers of the drawn sliver are much more twisted than the inner fibers. Upon further transport of the drawn sliver of false twisting wire is dissolved, with a core of the yarn thus produced almost completely loses its rotation. On the other hand remains in a coat of the yarn a permanent rotation, which holds the yarn together. The yarns thus obtained have a high uniformity.

The hybrid yarn according to the invention can now be produced simply by supplying to an air-spinning device a sliver of an intimate mixture of thermoplastic matrix fibers and reinforcing fibers. The core and sheath of the hybrid yarn are then simultaneously formed while passing through the air spinning device from a common fiber source, namely from the sliver presented to the air sliver. In this way, the hybrid yarn according to the invention can be produced inexpensively and nevertheless with a uniform shape. These advantages apply in particular to the use of wrapping devices in which the fibers forming the core of the yarn and the fibers forming the sheath are fed separately.

According to an expedient development of the invention, the air spinning process is a two-nozzle air spinning process. In such a method, the dissolving of the false twisting wire produced with a first swirling nozzle takes place with an oppositely acting second swirling nozzle. Such processes are particularly suitable for the production of hybrid yarns of longer staple fibers with a small proportion of fibers in the sheath. According to an expedient development of the invention, the air spinning process is an injection air spinning process. In such a method, the yarn formation takes place with only one swirl nozzle, which is arranged so that before the rotation of a portion of the outer fibers are spread apart. These splayed fibers are then wound around the core during reverse rotation. Such methods are particularly suitable for producing hybrid yarns of shorter staple fibers having a higher proportion of fibers in the sheath.

In another aspect, the invention relates to a fabric for making molded articles comprising a thermoplastic matrix and reinforcing fibers embedded therein. It is provided that the textile fabric comprises a hybrid yarn of the type described above, or that it consists of hybrid yarn of the type described above. This results in the already mentioned advantages.

According to an expedient development of the invention, the textile fabric is a knitted fabric, a knitted fabric, a woven fabric, a braid or a scrim. The hybrid yarn according to the invention can be processed with available textile machines in a simple manner with high efficiency in particular to knitted fabrics, knitted fabrics and braids. The production of loops is usually more complex, since scrims usually have to be stabilized by aids, for example by surrounding frames. However, the use of the loops gives rise to greater flexibility in the arrangement of the hybrid yarn, which in the case of knitted fabrics, knitted fabrics, woven fabrics and braids is at least partially predetermined by the technology used. In this way, moldings can be particularly well adapted to the expected mechanical loads. If, for example, the molded part or a region of the molded part is to be loaded only in one direction, then all sections of the hybrid yarn can be laid there so that their longitudinal direction coincides with the direction of the load. Furthermore, the invention relates to a molded part which has a thermoplastic matrix and reinforcing fibers embedded therein. In this case, the molding is produced by hot pressing a textile fabric of the type described above. This results in the already mentioned advantages.

The invention likewise relates to a method for producing a hybrid yarn of the type described above. It is provided that in one method step, a sliver consisting of an intimate mixture of thermoplastic matrix fibers and reinforcing fibers is produced, and in a further method step, the sliver by means of an air spinning device is spun.

Other advantageous embodiments and / or developments of the textile fabric according to the invention, the molding according to the invention and the method according to the invention are given above and / or in the subclaims.

The above advantageous embodiments and / or developments of the invention and / or reproduced in the dependent claims advantageous embodiments and / or developments of the invention may be provided individually or in any combination with each other.

The invention and its developments and their advantages are explained in more detail with reference to figures. Show it:

Figure 1 is an advantageous embodiment of an inventive

Hybrid yarn in a schematic side view and

Figure 2 is a block diagram of a method for producing a

Molded part, which is the production of a hybrid yarn according to FIG. 1 and the production of a textile fabric from the hybrid yarn.

Figure 1 shows an advantageous embodiment of a hybrid yarn 1 according to the invention for the production of moldings in a schematic side view. In this case, a longitudinal section A of the hybrid yarn 1 is shown, which merely shows a core 2 of the hybrid yarn 1 in order to illustrate the structure of the hybrid yarn 1. In a further illustrated longitudinal section A _{2 of} the hybrid yarn 1, the hybrid yarn 1 is shown completely, with a jacket 3 of the hybrid yarn 1 covering the core 2.

The core 2 consists of at least substantially in a longitudinal direction LR of the hybrid yarn 1 rectilinear staple fibers 4, 5. The staple fibers 4, 5 of the core 2 consist of thermoplastic matrix fibers 4 and of reinforcing fibers 5. For clarity, only some of the staple fibers 4, 5 provided with reference numerals. For the distinctness of the thermoplastic matrix fibers 4 and the reinforcing fibers 5, the former are white and the latter are filled with a dashed line. The staple fibers 4, 5 forming the core 2 consist of an intimate mixture 4, 5 of thermoplastic matrix fibers 4 and of reinforcing fibers 5.

The jacket 3, however, consists of staple fibers 6, 7, which are arranged helically around the staple fibers 4, 5 around. The staple fibers 6, 7 of the shell 3 are also made of thermoplastic matrix fibers 6 and of reinforcing fibers 7. Again, only some of the staple fibers 6, 7 provided with reference numerals. In this case, the thermoplastic matrix fibers 6 are also white and the reinforcing fibers 7 also filled with a dashed line to distinguish. In this case, the staple fibers 6, 7 forming the sheath 3 consist of an intimate mixture 6, 7 of thermoplastic matrix fibers 6 and of reinforcing fibers 7. From the staple fibers 4, 5, 6, 7 containing hybrid yarn 1 finished molded parts have transversely to the longitudinal direction LR of the hybrid yarn 1 higher strength than those moldings, which are made of continuous fibers, also called filaments, existing hybrid yarns. In particular, the cohesion of the individual layers can thus be improved in the case of molded parts which are produced from textile fabrics arranged in layers.

In addition, the hybrid yarn 1 has a lower void content than hybrid yarns with continuous fibers, which reduces the risk of undesirable air pockets during molding of the molded part, ie during consolidation of the textile fabric. In this way, the strength of the molded part is improved.

Furthermore, a fabric made of the hybrid yarn 1 is better drapable than a filament counterpart. This facilitates the wrinkle-free insertion of the textile fabric into the mold, at the same time reducing the risk of damage to the structure of the textile fabric. In this way, the manufacturing cost of the molding can be reduced. In addition, more complex shaped molded parts can be produced from textile fabrics, since the textile fabrics can be better applied to the contour of the molding tool.

Likewise, the danger is reduced by the use of staple fibers 4, 5, 6, 7, that the fibers in the further processing, in particular during draping, are kinked. This in turn is advantageous for the strength of the later molded part.

By now both the core 2 and the sheath 3 of the hybrid yarn 1 consists of staple fibers 4, 5, 6, 7, the aforementioned, by the use of staple fibers 4, 5, 6, 7 achievable advantages can be used to the maximum. In a lower section of FIG. 1, the rotation T in the hybrid yarn 1 according to the invention is shown as a function of the location x along a diameter of the hybrid yarn 1. It can be seen that in the region of the core 2 no rotation T is present. On the other hand, an essentially constant rotation T occurs in the region of the jacket 3.

It should be pointed out that FIG. 1 is an idealized representation of an exemplary embodiment of a hybrid yarn 1 according to the invention. In practice, the illustrated structure of the hybrid yarn 1 may include a core 2 of staple fibers 4, 5 rectilinearly oriented in a longitudinal direction LR of the hybrid yarn 1 and a sheath 3 of staple fibers 6, 7 helically arranged around the staple fibers 4, 5 of the core 2 be achieved with sufficient approximation, so that the advantages of the invention can be achieved. It should also be pointed out that FIG. 1 is not a true-to-scale representation.

The rectilinear arrangement, that is, the untwisted arrangement of the staple fibers 4, 5 of the core 2 in the longitudinal direction LR of the hybrid yarn 1, that the later molding in the longitudinal direction LR of the hybrid yarn 1 has a higher strength, in particular a higher tensile strength, than that in the Use of conventional hybrid yarns, in which the fibers are twisted over the entire cross section, would be possible. The reason for this is that in the molded part a substantial proportion of the reinforcing fibers 5, 7, namely the reinforcing fibers 5 of the core 2 of the hybrid yarn 1, runs parallel to one another in the longitudinal direction LR of the hybrid yarn 1.

Now, if the hybrid yarn 1 is arranged in the textile fabric so that its longitudinal direction LR at least partially corresponds to a main load direction of the later molded part, the molded part can better withstand mechanical stresses. In this way, the be improved ratio of mechanical strength and weight of the molding.

The necessary for further processing of the hybrid yarn 1 strength is ensured in the inventive hybrid yarn 1 essentially characterized in that the shell 3 forming staple fibers 6, 7 are wound helically around the core 2 and thus twisted.

The reinforcing fibers contained in the sheath 3 thereby improve the strength of the later molded part transversely to the longitudinal direction LR of the hybrid yarn 1 raised therein, in comparison with those shaped parts which are produced from hybrid fibers consisting of continuous fibers. As a result, the cohesion of the individual layers can be further improved in the case of molded parts which are produced from textile fabrics arranged in layers.

The staple fibers 4, 5 forming the core 2, as well as the staple fibers 6, 7 forming the sheath 3, each consist of an intimate mixture 4, 5, 6, 7 of thermoplastic matrix fibers 4, 6 and of reinforcing fibers 5, 7, respectively the use of intimate mixtures 4, 5 or 6, 7 ensures that in the fabric produced from the hybrid yarn 1, the thermoplastic matrix fibers 4, 6 and the reinforcing fibers 5, 7 are homogeneously distributed. In this way it can be achieved that the reinforcing fibers 5, 7 are completely wetted during melting of the thermoplastic matrix fibers 4, 6, so that in the later molding the interactions between the thermoplastic matrix and the reinforcing fibers 5, 7 are maximized by an improved cohesive connection, so that a mechanically highly resilient molding with low weight is created.

The volume-related proportion of the reinforcing fibers 5, 7 to a said intimate mixture 4, 5 or 6, 7 can expediently be at least 40%, preferably at least 45%, particularly preferably at least 50%. Furthermore, the volume-related proportion of the thermoplastic matrix fibers 4, 6 to a said intimate mixture can be 4, 5 or 6, 7 at least 20%, preferably at least 30%, particularly preferably at least 35%.

In principle, the intimate mixtures 4, 5 and 6, 7 can differ with respect to the thermoplastic matrix fibers 4 and 6 respectively contained therein. It is conceivable, for example, a different material composition and / or a different size, in particular a different thickness and / or staple length. Likewise, the intimate mixtures 4, 5 and 6, 7 can differ in terms of material and / or size with respect to the respectively contained therein reinforcing fibers 5 and 6 respectively. It is also possible that the proportionate composition of the intimate mixture 4, 5 differs from the proportionate composition of the intimate mixture 6, 7. Preferably, however, the intimate mixture 4, 5 forming the core 3 and the intimate mixture 6, 7 forming the shell 3 correspond in terms of their material and the dimensions of their staple fibers 4, 5; 6.7.

In the case of the hybrid yarn 1, the sum of the volume-related portion of the thermoplastic matrix fibers 4, 6 and the volume-related portion of the reinforcing fibers 5, 7 on the hybrid yarn 1 can be at least 90%, preferably at least 95%, particularly preferably at least 98%. The remaining volume fractions can be attributed, for example, to a size or adhesion promoter.

The staple fibers 4, 5 forming the core 2 and / or the staple fibers 6, 7 forming the shell 3 may have a length of at least 2.5 cm, preferably of at least 5 cm, more preferably of at least 10 cm and / or a length of at most 25 cm, preferably of at most 20 cm, more preferably of at most 15 cm. The thermoplastic matrix fibers 4, 6 may in particular have a fineness-related maximum tensile force of at least 20 cN / tex, preferably of at least 30 cN / tex, more preferably of at least 50 cN / tex. In this case, the thermoplastic matrix fibers 4, 6 preferably comprise polyurethane fibers, polyamide fibers and / or polyester fibers. The thermoplastic matrix fibers 4, 6 of the hybrid yarn 1 preferably consist of a single material.

The reinforcing fibers 5, 7 may have a tenacity of at least 100 cN / tex, preferably at least 150 cN / tex, more preferably at least 200 cN / tex. The reinforcing fibers 5, 7 preferably comprise glass fibers, carbon fibers and / or arabin fibers. Preferably, the reinforcing fibers 5, 7 consist of a single material.

The rotation coefficient a _{m of} the hybrid yarn 1 is expediently at most 200, preferably at most 170, particularly preferably at most 150, and / or at least 70, preferably at least 90, particularly preferably at least 110.

The hybrid yarn 1 preferably has a total titer of at least 100 dtex, preferably of at least 150 dtex, more preferably of at least 200 dtex, and / or of at most 15000 dtex, preferably of at most 12000 dtex, more preferably of at most 10000 dtex. The proportion of the staple fibers forming the sheath on the staple fibers can be at least 5%, preferably at least 10%, particularly preferably at least 15% and / or at most 45%, preferably at most 35%, particularly preferably at most 25%. In particular, the Kringelneigung of the hybrid yarn 1 may be at most 200 1 / m, preferably at most 180 1 / m, more preferably at most 160 1 / m. FIG. 2 illustrates a method for producing a molded part 8, which comprises the production of a hybrid yarn 1 according to FIG. 1 and the production of a textile fabric 9 from the hybrid yarn 1. The definition is that procedural steps are represented by rectangles and the results of the method steps by octagons.

The production of the hybrid yarn 1 comprises a method step 10 for producing a substantially untwisted sliver 1 1, which consists of an intimate mixture 4, 5, 6, 7 of thermoplastic matrix fibers 4, 6 and of reinforcing fibers 5, 7.

The method step 10 may be configured such that staple fibers 4, 5 which are in the form of flakes and which are thermoplastic matrix fibers 4, 5, and also flake-form staple fibers 6, 7, which are reinforcing fibers 6, 7, are fed to a flake mixing machine. In this way, an intimate mixture 4, 5, 6, 7 can be prepared in flake form, which can then be supplied to a card. By means of the card, this intimate mixture 4, 5, 6, 7 then be formed into a sliver. This sliver can then optionally one or more times guided over a distance and thereby refined and / or homogenized, that a spinnable sliver 1 1 is formed, which is an intimate mixture of thermoplastic matrix fibers 4, 5 and of reinforcing fibers 6, 7, respectively Stack form, includes.

Alternatively, the method step 10 may be configured such that the staple fibers 4, 5 present in flake form, which are thermoplastic matrix fibers 4, 5, are formed by means of a card into sliver of a first type, which essentially comprises thermoplastic matrix fibers 4, 5. From the present in flake form staple fibers 6, 7, which are reinforcing fibers 6, 7, sliver of a second type is also produced by means of a card, which essentially comprises reinforcing fibers 6, 7. By concealed one or more hiding little At least one sliver of the first type and at least one sliver of the second type by means of a Doublierstrecke then a spinnable sliver 1 1 can be prepared which comprises an intimate mixture of thermoplastic matrix fibers 4, 5 and of reinforcing fibers 6, 7, each in a stacked form.

In a method step 12, the sliver 1 1 is then fed to an air-spinning device. In this case, the substantially untwisted sliver 1 1 is stretched to the desired fineness and passed through an air stream, which gives the stretched sliver 1 1 a false twist. In this case, the outer staple fibers 6, 7 of the drawn sliver 1 1 are rotated much stronger than the inner staple fibers 4, 5. During further transport of the drawn sliver 1 1 of the false twisting wire is substantially dissolved, with the untwisted core 2 and the twisted shell 2 of Hybrid yarn 1 trains.

The air spinning device can work according to a two-nozzle air spinning process. In such a method, the dissolving of the false twisting wire produced with a first swirling nozzle takes place with an oppositely acting second swirling nozzle.

Alternatively, the air spinning device may be based on an injection air spinning process. In such a method, the formation of the hybrid yarn 1 is carried out with only one swirl nozzle, which is arranged so that prior to the twisting part of the outer staple fibers 6, 7 are spread apart. These splayed staple fibers 6, 7 are then wound around the core 2 during reverse rotation.

The staple fibers 4, 6 made of thermoplastic material supplied to method step 10 can be produced by first producing continuous fibers 14 of thermoplastic material in a method step 13. These endless fibers 14 can be produced, for example, by melt spinning can be generated. In a further method step 15, the continuous fibers 14 can be brought to the required length, for example by cutting or by tearing, so that the staple fibers 4, 6 are formed.

Similarly, the staple fibers 5, 7 supplied to the method step 10 can be produced from reinforcing material, by first producing endless fibers 17 from reinforcing material in a method step 16. These endless fibers 17 can also be, for example, by

Melt spinning can be generated. In a further method step 18, the endless fibers 17 can be cut to length by cutting or tearing, for example, so that the staple fibers 5, 7 are formed.

In order to produce a textile fabric 9 from the hybrid yarn 1, a method step 19 is provided. This may include a common method of making a knitted fabric, a knit fabric, a woven fabric, a braid or a fabric.

From the textile fabric 9 thus produced or from a plurality of textile fabrics 9 produced in this way, a molded part 8 can then be produced in a method step 20 by consolidating the thermoplastic matrix fibers 4, 6. Here, known hot pressing methods can be used.

The novel molding 8 thereby obtains its superior mechanical properties essentially by the use of the hybrid yarn 1 described above in the production of the molding.

Claims

Patent claims

1 . Hybrid yarn (1) for producing molded parts (8) comprising a thermoplastic matrix and reinforcing fibers (4, 5, 6, 7) embedded therein, characterized in that it comprises a core (2) consisting essentially of in a longitudinal direction ( LR) of the hybrid yarn (1) consists of rectilinear staple fibers (4, 5), and a sheath (3) consisting essentially of helically wrapped staple fibers (6, 7) wrapped around the core (2) comprises the core (2) forming staple fibers (4, 5) and the sheath (3) forming staple fibers (6, 7) each of an intimate mixture (4, 5; 6, 7) of thermoplastic matrix fibers (4, 6) and of reinforcing fibers ( 5, 7) exist.

2. hybrid yarn (1) according to the preceding claim, characterized in that the volume-related proportion of the reinforcing fibers (5, 7) to a said intimate mixture (4, 5; 6, 7) at least 40%, preferably at least 45%, particularly preferred at least 50%.

3. hybrid yarn (1) according to any one of the preceding claims, characterized in that the volume-related proportion of the thermoplastic matrix fibers (4, 6) to said intimate mixture (4, 5; 6, 7) at least 20%, preferably at least 30%, more preferably at least 35%.

4. hybrid yarn (1) according to any one of the preceding claims, characterized in that the core (2) forming staple fibers (4, 5) and the shell (3) forming staple fibers (6, 7) with respect to their said intimate mixture ( 4, 5, 6, 7).

Hybrid yarn (1) according to one of the preceding claims, characterized in that the sum of the volume-related portion of the thermoplastic matrix fibers (4, 6) and the volume-related portion of the reinforcing fibers (5, 7) on the hybrid yarn (1) is at least 90%, preferably at least 95%, more preferably at least 98%.

6. hybrid yarn (1) according to any one of the preceding claims, characterized in that the core (2) forming staple fibers (4, 5) and / or the shell (3) forming staple fibers (6, 7) has a length of at least 2 , 5 cm, preferably of at least 5 cm, more preferably of at least 10 cm and / or a length of at most 25 cm, preferably of at most 20 cm, particularly preferably of at most 15 cm.

7. Hybrid yarn (1) according to any one of the preceding claims, characterized in that the thermoplastic matrix fibers (4, 6) has a fineness-related maximum tensile force of at least 20 cN / tex, preferably of at least 30 cN / tex, more preferably of at least 50 cN / tex.

Hybrid yarn (1) according to any one of the preceding claims, characterized in that the thermoplastic matrix fibers (4, 6) comprise polyurethane fibers, polyamide fibers, polyether ketone fibers, polypropylene fibers, acrylonitrile-butadiene-styrene fibers and / or polyester fibers.

9. hybrid yarn (1) according to any one of the preceding claims, characterized in that the thermoplastic matrix fibers (4, 6) consist of a single material.

10. Hybrid yarn (1) according to one of the preceding claims, characterized in that the reinforcing fibers (5, 7) have a fineness-related maximum tensile force of at least 100 cN / tex, preferably of at least 150 cN / tex, more preferably of at least 200 cN / tex.

1 1. Hybrid yarn (1) according to one of the preceding claims, characterized in that the reinforcing fibers (5, 7) comprise glass fibers, carbon fibers and / or aramid fibers.

12. hybrid yarn (1) according to any one of the preceding claims, characterized in that the reinforcing fibers (5, 7) consist of a single material.

13. hybrid yarn (1) according to any one of the preceding claims, characterized in that its rotation coefficient a _{m is} at most 200, preferably at most 170, more preferably at most 150, and / or at least 70, preferably at least 90, more preferably at least 1 10.

Hybrid yarn (1) according to any one of the preceding claims, characterized in that it has a total titer of at least 100 dtex, preferably at least 150 dtex, more preferably at least 200 dtex, and / or at most 15000 dtex, preferably at most 12000 dtex , more preferably of at most 10000 dtex.

15. hybrid yarn (1) according to any one of the preceding claims, characterized in that the volume-related proportion of the sheath (3) forming staple fibers (6, 7) on the staple fibers (4, 5, 6, 7) at least 2%, preferably at least 5%, particularly preferably at least 15% and / or at most 45%, preferably at most 35%, particularly preferably at most 25%.

16. hybrid yarn (1) according to any one of the preceding claims, characterized in that the Kringelneigung at most 200 1 / m, preferably at most 180 1 / m, more preferably at most 160 1 / m.

17. Hybrid yarn (1) according to one of the preceding claims, characterized in that it is produced by means of an air spinning process (12).

18. hybrid yarn (1) according to any one of the preceding claims, characterized in that the air spinning process (12) is a two-nozzle air spinning process.

19. hybrid yarn (1) according to any one of the preceding claims, characterized in that the air spinning process (12) is an injection air spinning process.

A textile fabric (9) for producing molded parts (8) which have a thermoplastic matrix and reinforcing fibers (5, 7) embedded therein, characterized in that it comprises hybrid yarn (1) according to one of the preceding claims, or that it comprises Hybrid yarn (1) according to one of the preceding claims.

21. Textile fabric (9) according to claim 20, characterized in that it is a knitted fabric, a knitted fabric, a woven fabric, a mesh or a scrim.

22. molding (8), which has a thermoplastic matrix and embedded therein reinforcing fibers (5, 7), characterized in that it is produced by hot pressing a textile fabric (9) according to any one of claims 20 to 21. Method for producing a hybrid yarn (1) according to one of Claims 1 to 19, characterized in that in a method step (10) a sliver (11) consisting of an intimate mixture (4, 5, 6, 7) of thermoplastic matrix fibers ( 4, 6) and of reinforcing fibers (5, 6) is produced, and that in a further process step (12) the sliver (1 1) is spun by means of an air spinning device.