EP3015576A1 - Method and device for the preparation of carbon fibre semi-finished products - Google Patents

Abstract

The present invention relates to a process for the preparation of fiber webs for the production of carbon fiber semi-finished products, comprising the following steps: a) providing Fasergewirren at least containing carbon fibers and / or carbon fiber bundles in a swirl region; b) at least partially separating the fiber webs in a turbulent flow in the vortex region to obtain isolated carbon fibers and / or carbon fiber bundles; c) optionally wind views of the singulated carbon fibers and / or carbon fiber bundles in the vortex region to obtain fractionated carbon fibers and / or carbon fiber bundles; d) discharging the separated and / or fractionated carbon fibers and / or carbon fiber bundles from the swirl region obtained in step b) into an alignment region, wherein the carbon fiber semi-finished products are obtained in or subsequent to step d).

Description

BACKGROUND OF THE INVENTION

The present invention relates to a method and an apparatus for the production of carbon fiber semi-finished carbon fiber yarns. Another object of the invention is a carbon fiber tape obtainable by the method and its use.

STATE OF THE ART

Methods of making carbon staple fibers are known in the art. Here, carbon fiber wefts and / or flakes are processed by a carding process and provided as a card sliver. The purpose of the carding process is the dissolution of the carbon fiber wefts and / or flakes into individual fibers or fiber bundles and their orientation along the fiber axis. In the carding belt produced in this way, the fibers are largely oriented and are suitable for further processing up to the desired end product.

That's how it describes DE 10 2009 023 529 For example, a method for recycling fiber composite waste from unimpregnated carbon fibers, in which the fiber composite waste is cut and digested by impactors. The resulting fiber worms are then restructured into fiber webs or webs. The composite waste is processed in the described method under a high mechanical load into fiber entanglements.

The WO 2011/134995 in turn, describes a hybrid yarn for making molded articles consisting of a core of rectilinear staple fibers and a sheath of staple fibers wound around the core. The staple fibers each consist of reinforcing fibers embedded in a thermoplastic matrix.

In the WO 2012/000827 For example, a method for producing a sewing thread from carbon fiber materials is described. The fibers of the sewing thread described are staple fibers of finite length of stretched or cut multifilament yarns which are spun together to form a yarn and coated or impregnated.

From the WO 2011/095826 is a spun yarn made from recycled carbon fibers. The recycled carbon fibers can come from different sources and are obtained by cutting a recycled carbon fiber material. The method described comprises separating, digesting, blending, and spinning the carbon fibers into a yarn.

The EP 1 854 911 A1 describes a hybrid carbon fiber spun yarn having a core region and an outer region surrounding the core region. At least 20% by mass of the fibers in the core region are "long" carbon fibers having a length of 500 mm or more, and in the outer region at least 80% by mass of the fibers are "short" carbon fibers having a fiber length of less than 500 mm.

The EP 1 696 057 describes a method of making a carbon fiber ribbon starting from a mat of stacked, pitch-oriented oriented grain carbon fibers. The obtained carbon fiber ribbon is pulled and twisted to obtain a carbon fiber spun yarn having 50 to 400 primary twist / m and at least 3 wt% of fibers having a fiber length of at least 150 mm.

Carbon fibers, also known as carbon fibers, are industrially produced fibers from carbonaceous organic feedstocks that are converted to graphitic carbon by pyrolysis. It is possible to distinguish isotropic and anisotropic types of carbon fibers. The isotropic carbon fibers have only low strengths and less technical importance. Due to their chemical structure, the anisotropic carbon fibers show high strengths and stiffnesses with low elongation at break in the axial direction and are of great industrial significance. Due to these properties, carbon fibers are only extensible to a very small extent and are also susceptible to forces acting transversely to the fiber longitudinal axis. Processes known in the prior art for the production of carbon fiber semifinished products therefore usually lead to a significant reduction in the average fiber length and to loss of strength due to the process.

Known processes for the production of carbon fiber semi-finished products usually describe production processes of staple fibers. The known methods often have the disadvantage that they lead to a reduction of the mechanical properties of the individual fibers. In particular, during carding or combing processes, the fibers experience high rates of acceleration and / or heavy stress due to shear and deflection forces. which results, for example, in a strong reduction of the mean fiber lengths and thus reduced strength properties.

The present invention is therefore based on the object to provide an improved process for the processing of carbon fiber entanglements, in which the aforementioned disadvantages are avoided. In particular, a fiber-sparing preparation of carbon fiber worms is to be made available in which the structural and mechanical properties of the processed carbon fibers are preserved or only slightly damaged. Furthermore, the average fiber length of the carbon fibers should be largely retained from the carbon fiber entanglements used. Furthermore, the method should be procedurally simple to implement and with little structural effort.

DESCRIPTION OF THE INVENTION

Surprisingly, it has now been found that carbon fiber worms can be separated in a technologically simple manner in a turbulent air stream into fiber bundles or individual fibers. The thus separated carbon fibers can be stored with a high degree of orientation of the individual fibers or fiber bundles in the fiber longitudinal direction to a band. A fiber band produced in this way can be subjected to a suitable binding agent and thus solidified for the purpose of fixing or connecting separated individual fibers to one another. Furthermore, a sliver produced in this way can be profiled or shaped and provided for further processing steps.

1. a) Bereitstellen von Fasergewirren wenigstens enthaltend Carbonfasern und/oder Carbonfaserbündel in einem Wirbelbereich;
2. b) wenigstens teilweises Vereinzeln der Fasergewirre in einer turbulenten Strömung im Wirbelbereich unter Erhalt vereinzelter Carbonfasern und/oder Carbonfaserbündel;
3. c) gegebenenfalls Windsichten der vereinzelten Carbonfasern und/oder Carbonfaserbündel im Wirbelbereich unter Erhalt fraktionierter Carbonfasern und/oder Carbonfaserbündel; und
4. d) Austragen der in Schritt b) erhaltenen vereinzelten und/oder in Schritt c) fraktionierten Carbonfasern und/oder Carbonfaserbündel aus dem Wirbelbereich in einen Ausrichtungsbereich.

According to the invention, this object is achieved by a process for the preparation of fiber wovens for the production of semi-finished carbon fiber products, which comprises the following steps:

1. a) providing Fasergewirren at least containing carbon fibers and / or carbon fiber bundles in a swirl region;
2. b) at least partially separating the fiber webs in a turbulent flow in the vortex region to obtain isolated carbon fibers and / or carbon fiber bundles;
3. c) if appropriate, air classification of the singulated carbon fibers and / or carbon fiber bundles in the vortex region to obtain fractionated carbon fibers and / or carbon fiber bundles; and
4. d) discharging the isolated and / or fractionated in step c) carbon fibers and / or carbon fiber bundles from the swirl region in an alignment region.

The semi-finished carbon fiber products are obtained in or subsequent to step d).

In the context of the present invention, processing means a recycling process by recycling for the reuse of Fasergewirren be processed in the defined waste streams or parts of Fasergewirren to recover from it again marketable secondary raw materials. In the context of the present invention, the intention is to exclude the use of energy and the preparation of materials intended for use as fuel or for backfilling.

In the context of the present invention, fiber structures are understood to mean flat or spatial structures, such as scrims, woven fabrics, braids, knitted fabrics, knitted fabrics, flakes and any combination thereof. The fiber wovens to be used according to the invention contain carbon fiber constituents of generally at least 1% by weight, for example in the range from 1 to 100% by weight, preferably at least 5% by weight, for example in the range from 5 to 100% by weight preferably at least 10 wt .-%, for example in the range of 10 to 100 wt .-%, in particular at least 15 wt .-%, for example in the range of 15 to 100 wt .-%.

In the context of the present invention, carbon fiber semifinished products are band, line and / or thread-like structures made of carbon fibers. According to the invention, the semi-finished carbon fiber products are obtained in or following step d). In addition to the alignment carried out in step d), they may be subjected to a fabrication in one or more further steps. Carbon fiber semi-finished products obtained in accordance with the invention generally contain carbon fiber constituents of at least 50% by weight, for example in the range from 50 to 100% by weight, preferably at least 60% by weight, for example in the range from 60 to 100% by weight preferably at least 75 wt .-%, for example in the range of 75 to 100 wt .-%, in particular at least 90 wt .-%, for example in the range of 90 to 100 wt .-%.

In the context of the present invention, carbon fibers, here and hereinafter also referred to as carbon fibers, are industrially produced carbon-containing fibers organic starting materials, which are converted, for example by pyrolysis in graphitic carbon, understood. It may be both isotropic and anisotropic types of carbon fibers. The isotropic carbon fibers have comparatively low strengths. The anisotropic carbon fibers, however, have due to their chemical structure high strength and stiffness with low elongation at break in the axial direction. At least partially anisotropic carbon fibers are preferably used in the context of the present invention. The carbon fibers used in the present invention generally have a diameter in the micrometer range, for example in the range of 1 to 100 .mu.m, preferably in the range of 2 to 50 .mu.m, in particular in the range of 5 to 10 microns.

In the context of the present invention, a carbon fiber bundle is understood to mean a bundle composed of carbon fibers. A carbon fiber bundle may also comprise fibers other than carbon fibers. As a rule, such a carbon fiber bundle consists of 10 to 400,000 individual fibers, preferably from 10 to 100,000 individual fibers, in particular from 100 to 10,000 individual fibers.

In the context of the present invention, fractionated carbon fibers or carbon fiber bundles are understood as meaning individual fibers or fiber bundles which are separated from a fiber tangle and have different properties, such as geometric dimensions, in particular length, diameter, area, shape, such as density, such as flow resistance, such as composition, etc., separated and optionally separated from impurities.

In the context of the present invention, a vortex region is understood as meaning an area of a device or a device in which a fluid is fluidized. In particular, swirling in the spinal area is non-invasive in a highly turbulent flow.

In the context of the present invention, a turbulent flow is understood to mean the movement of fluids in which turbulences occur. The turbulent flow is characterized by mostly three-dimensional, seemingly random, unsteady movements of fluid particles. The fluctuation movement leads to increased diffusion, which is several orders of magnitude greater than the molecular diffusion.

For the purposes of the present invention, air classification means the fractionation of the carbon fibers and / or carbon fiber bundles according to their geometric dimensions.

In the context of the present invention, the term alignment region is understood as meaning a region of a device and / or device for increasing the orientation of the fibers in their longitudinal direction.

• e) Ausrichten der in Schritt d) ausgetragenen Carbonfasern und/oder Carbonfaserbündel in Strömungsrichtung einer laminaren Strömung im Ausrichtungsbereich, wobei die Carbonfasern und/oder Carbonfaserbündel entlang ihrer Längsachse gestreckt vorliegen;
• f) Ausströmen der in Schritt d) ausgetragenen und gegebenenfalls in Schritt e) in Strömungsrichtung der laminaren Strömung ausgerichteten Carbonfasern und/oder Carbonfaserbündel;
• g) Ablegen der in Schritt d) ausgetragenen und gegebenenfalls in Schritt e) in Strömungsrichtung der laminaren Strömung ausgerichteten und/oder gegebenenfalls in Schritt f) erhaltenen ausströmenden Carbonfasern und/oder Carbonfaserbündel als ein Carbonfaserband in einem Ablegebereich.

The method according to the invention preferably additionally comprises at least one of the following steps:

• e) aligning the carbon fibers and / or carbon fiber bundles discharged in step d) in the direction of flow of a laminar flow in the alignment region, wherein the carbon fibers and / or carbon fiber bundles are stretched along their longitudinal axis;
• f) outflow of the carbon fibers and / or carbon fiber bundles discharged in step d) and optionally aligned in step e) in the direction of flow of the laminar flow;
• g) depositing the effluent carbon fibers and / or carbon fiber bundles discharged in step d) and optionally in step e) in the flow direction of the laminar flow and / or optionally obtained in step f) as a carbon fiber strip in a deposition area.

In the context of the present invention, a laminar flow is understood to mean a movement of liquids and gases in which no visible turbulences, such as turbulences or crossflows, occur. Liquids and gases are referred to here and below as fluids. The fluid flows in laminar flow in layers that do not mix with each other. At a constant flow rate, a laminar flow is usually a steady state flow.

In the context of the present invention, a carbon fiber tape is understood to mean a strip-shaped fabric or scrim made of isolated fibers with a limited width and a longitudinal axis.

In the context of the present invention, a depositing area is an area of a device and / or device for the uniform collection of separated carbon fibers and / or carbon fiber bundles understood. The carbon fibers are oriented in particular uniformly in their longitudinal direction.

The process according to the invention for the steps a) to d) particularly preferably comprises at least step g).

• h) Lagenbilden des in Schritt g) erhaltenen Carbonfaserbandes;
• i) Profilieren des in Schritt g) erhaltenen Carbonfaserbandes;
• j) Aufbringen mindestens eines Bindemittels wenigstens auf Teilbereiche des in Schritt g) erhaltenen Carbonfaserbandes mit einer Auftragsvorrichtung unter Ausbildung eines wenigstens in Teilbereichen mit dem mindestens einen Bindemittel punktuell und/oder flächig benetzten Carbonfaserbandes;
• k) Profilieren des in Schritt j) erhaltenen, wenigstens in Teilbereichen mit dem mindestens einen Bindemittel punktuell und/oder flächig benetzten Carbonfaserbandes;
• I) Fixieren des in einem der Schritte j) oder k) erhaltenen, wenigstens in Teilbereichen mit dem mindestens einen Bindemittel punktuell und/oder flächig benetzten Carbonfaserbandes; und/oder
• m) Aufbringen einer Schlichte wenigstens auf Teilbereiche des in Schritt g) erhaltenen Carbonfaserbandes mit einer Auftragsvorrichtung.

According to a particularly suitable embodiment, in addition to step g), the process according to the invention comprises at least one of the following steps:

• h) layer forming the carbon fiber ribbon obtained in step g);
• i) profiling the carbon fiber ribbon obtained in step g);
• j) application of at least one binder to at least portions of the carbon fiber tape obtained in step g) with an applicator to form a at least in some areas with the at least one binder selectively and / or surface wetted carbon fiber tape;
• k) profiling of the carbon fiber band obtained in step j), at least in some areas with the at least one binder selectively and / or wetted surface;
• I) fixing the carbon fiber band obtained in one of the steps j) or k), at least in some areas with the at least one binder, in a point-wise and / or flat-wetted manner; and or
• m) applying a size to at least portions of the carbon fiber tape obtained in step g) with an applicator.

In the context of the present invention, layering is understood to mean the stacking, in particular superimposition, unification of several carbon fiber ribbons.

In the context of the present invention profiling is understood to mean a shaping step. For this purpose, the carbon fiber tape is passed through a device with a suitable profile tool, wherein the desired cross-sectional profile of the carbon fiber tape is configured. The profiling may additionally comprise a surface treatment.

In the context of the present invention, binder is understood to mean an additive and / or a composition for fixing the geometric arrangement of carbon fiber ribbons and their constituents, in particular filament geometries.

In the context of the present invention, fixing is understood in particular to be the thermal solidification of a binder applied to carbon fiber ribbons and their constituents.

In the context of the present invention, point and / or surface wetted carbon fiber ribbons are understood as meaning the application of binders to a profiled carbon fiber tape.

In the context of the present invention, the term sizing is understood as meaning the application of sizing agents and / or sizing compositions to profiled and fixed carbon fiber ribbons.

In a preferred embodiment of the method according to the invention, the turbulent flow in the vortex region is generated pneumatically in step b).

In a further preferred embodiment of the method according to the invention, the turbulent flow in the vortex region is generated in step b) by means of static and / or dynamic vortex elements arranged in the vortex region.

In the context of the present invention, a whirl element is generally understood to mean a device which causes swirling of the fluid flow, here and hereinafter also referred to as whirl. Vortexes can be forced by static vortex elements as well as by dynamic vortex elements. Under static vortex elements are here and below rigid or stationary solids, which are flowed around by a fluid to be understood. Examples of static vortex elements are all types of fixed baffles. Under dynamic vortex elements here and below moving devices, which in turn make a fluid in motion, to be understood. Examples of dynamic vortex elements are all types of stirrers.

In a preferred embodiment of the method according to the invention, the turbulent flow in the vortex region in step b) with compressed air in a range of 0.1 to 3 MPa absolute, preferably in a range of 0.15 to 2 MPa absolute, more preferably in a range of 0.2 to 1 MPa produced absolutely.

In particular, the turbulent flow in the vortex region in step b) is characterized by a Reynolds number greater than 1200.

The Reynolds number, here and hereafter also referred to as Re-number or simply as Re, is a dimensionless index which represents the ratio of inertial to ductile forces. The turbulence behavior of geometrically similar bodies is the same for a corresponding Reynolds number. $$\mathrm{re}=\frac{\mathrm{\rho }*\mathrm{u}*\mathrm{d}}{\mathrm{\eta }}=\frac{\mathrm{u}*\mathrm{d}}{\mathrm{\nu }}\mathrm{With}\mathrm{\eta }=\mathrm{\nu }*\mathrm{\rho }$$

ρ :

Dichte des Fluids (kg m^-3)

u :

relative Strömungsgeschwindigkeit des Fluids (m s^-1)

d :

charakteristische Länge des Gegenstandes (m)

η :

dynamische Viskosität des Fluids (kg s^-1 m^-1)

v :

kinematische Viskosität des Fluids (m² s^-1)

The individual formula symbols stand for the following sizes:

ρ:

Density of the fluid (kg m ^-3)

u:

relative flow velocity of the fluid (ms ^-1 )

d:

characteristic length of the object (m)

η:

dynamic viscosity of the fluid (kg s ^-1 m ^-1 )

v:

kinematic viscosity of the fluid (m ² s ^-1 )

The characteristic length, also referred to as reference length, can in principle be chosen freely. When comparing two flows, however, this length must be the same type. For pipe flows, here and in the following, the clear diameter of the pipe is chosen as the reference length. If the Reynolds number exceeds a system-dependent critical value Re _crit , a laminar flow until then becomes susceptible to minute disturbances. Correspondingly, Re> Re _{crit is} expected to _undergo a transition from laminar to turbulent flow.

In a further preferred embodiment of the method according to the invention, the turbulent flow in the vortex region in step b) is a stationary flow, a discontinuous flow, a pulsating flow and / or an alternating combination thereof.

A stationary flow is understood here and below to mean a flow without significant temporal change of the flow state.

A discontinuous flow is understood here and below as meaning a flow which undergoes a discontinuous, jerky and / or abrupt change in the flow state with respect to the time or the location.

In the context of the present invention, a pulsating flow is understood as meaning a continuous, transient flow in which the speed and pressure at a fixed location change periodically. Periodic transient flow processes can be treated as quasi-stationary processes if the frequency of the state changes is sufficiently small, since the same averaged flow state is present at all times as in a stationary flow.

In particular, the laminar flow in the alignment region in step e) is characterized by a Reynolds number in the range of 10 to 1200.

In the context of the present invention, an alignment region is understood as meaning a region of a device and / or device for increasing the orientation of the fibers in their longitudinal direction. In particular, the increase in the orientation of the fibers in their longitudinal direction in an alignment region is improved with a reduction in fluid velocity and the formation of a laminar flow.

In a preferred embodiment of the method according to the invention, the deposition area in step g) is subjected to a force field. In this case, the force field generation is selected from a negative pressure, an electric field, a magnetic field, an adhesive force, combinations thereof.

In a suitable embodiment of the method according to the invention, the deposition area in step g) is subjected to a vacuum in a range of 50 to 70 hPa absolute.

In a likewise suitable embodiment of the method according to the invention, the depositing area in step g) is subjected to an electrical voltage of more than 15 kV.

In a preferred embodiment of the method according to the invention, no torsional force is exerted on the effluent carbon fibers and / or carbon fiber bundles obtained in step f) and / or the carbon fiber strip obtained in step g).

In the context of the present invention, torsional force is understood to mean a force for the twisting of a carbon fiber band along the longitudinal extension axis.

In a preferred embodiment of the method according to the invention, the layer formation in step h) takes place with a winding device which rotates in a direction coinciding with the longitudinal axis of the carbon fiber strip obtained in step g). In particular, the layer formation in step h) takes place with its own longitudinal axis rotating take-up device and / or arranged at a right angle to the longitudinal axis of the carbon fiber strip obtained in step g).

In the context of the present invention, a winding device is understood to mean a device for winding up a carbon fiber tape. In particular, the winding device is a vacuum-loaded drum with a perforated surface on which a carbon fiber tape is wound.

In a further preferred embodiment of the method according to the invention, after profiling in step i) and / or in step k), the carbon fiber tape has a cross-sectional profile according to the geometric shape of the profiling tool.

In the context of the present invention, a profiling tool is understood to mean a tool giving shape to the carbon fiber tape.

In particular, the carbon fiber tape has a cross section with an oval, in particular an elliptical or round, a triangular, a quadrangular, in particular a rectangular or square, a regular polygonal shape or any combination of said forms. Particularly suitable are convex cross-sectional shapes or a combination of two or more convex cross-sectional shapes to a non-convex inner cross-section, such as an angular or a T-profile. Also suitable are non-convex cross-sections in a curved or round shape, such as a sickle-shaped or annular cross-section.

According to a preferred embodiment, the method according to the invention comprises at least step j) in addition to step g).

In a particularly preferred embodiment, the application of the at least one binder in step j) is carried out by one of the method selected from dipping, sumping, immersing, spraying, impregnating, sprinkling, coating, curtain coating, transfer roll application, combinations thereof.

• mindestens einen Wirbelbehälter;
• mindestens einen Wirbelbehältereinlauf;
• mindestens einen Wirbelbehälterauslauf;
• mindestens ein Ausrichtungselement, wobei das Ausrichtungselement in Auslaufströmungsrichtung nach dem mindestens einen Wirbelbehälterauslauf angeordnet ist; und
• mindestens ein Ausströmelement, wobei das Ausströmelement in Auslaufströmungsrichtung nach dem mindestens einen Ausrichtungselement angeordnet ist,

umfasst. Dabei ist das Ausströmelement derart ausgestaltet, dass der lichte Durchmesser an seinem Einlauf größer ist als an seinem Auslauf.The invention also provides a device for the treatment of Fasergewirren for the production of carbon fiber semi-finished products, the

• at least one vortex container;
• at least one vortex tank inlet;
• at least one vortex tank outlet;
• at least one alignment element, wherein the alignment element is arranged in the outlet flow direction after the at least one vortex container outlet; and
• at least one outflow element, wherein the outflow element is arranged in the outlet flow direction downstream of the at least one alignment element,

includes. In this case, the outflow is designed such that the clear diameter is greater at its inlet than at its outlet.

In the context of the present invention, a vortex container is understood as meaning a mixing device which essentially comprises a container, a vessel or a chamber, in which a fluid is fluidized. In particular, swirling in the spinal area is non-invasive.

In the context of the present invention, the term vortex container inlet is understood to mean a device and / or device for supplying at least partially ununsulated fiber entanglements.

• vereinzelt,
• bezüglich der Ausrichtung linearisiert,
• beruhigt und
• abgelegt.

With the device according to the invention, fiber wovens for the production of carbon fiber semi-finished products can be processed in a particularly gentle way. Here are the carbon fibers or carbon fiber bundles

• occasionally,
• linearized with respect to orientation,
• calms down and
• stored.

In the context of the present invention, the term "vortex container outlet" is understood to mean an apparatus and / or device for a discharge of at least partially separated fiber entanglements, in particular singulated carbon fibers and / or carbon fiber bundles. In particular, a vortex container outlet is designed as a diaphragm.

In the context of the present invention, an alignment element is a device for aligning carbon fibers and / or carbon fiber bundles along their Longitudinal axis understood. The alignment element can be traversed by carbon fibers and / or carbon fiber bundles and has a longitudinal axis and a clear diameter. In particular, the alignment element is a tube.

In the context of the present invention, an outflow element is understood to be a device and / or device for a discharge of at least partially separated fiber worms, in particular singulated carbon fibers and / or carbon fiber bundles, which is arranged downstream of the discharge element. In particular, a discharge element is configured as a discharge nozzle, a diffuser and combinations thereof.

• mindestens eine Abnahmevorrichtung mit einem Ablegebereich;
• mindestens ein erstes Profilwerkzeug;
• mindestens eine Auftragsvorrichtung;
• mindestens ein zweites Profilwerkzeug, welches nach der mindestens einen Auftragsvorrichtung angeordnet ist;
• mindestens eine Fixiervorrichtung.

In a preferred embodiment, the device according to the invention additionally comprises at least one of the following components:

• at least one removal device with a deposit area;
• at least a first profile tool;
• at least one applicator device;
• at least one second profile tool, which is arranged after the at least one application device;
• at least one fixing device.

According to a further preferred embodiment, the device according to the invention is characterized in that the at least one alignment element and / or the at least one outflow element is selected from a pipe, a pipe, a hose or combinations thereof.

According to a further preferred embodiment, the device according to the invention is characterized in that the at least one vortex container outlet is selected from a venturi, an orifice, a bore, a flap, a tube constriction, a valve, a slide, a diffuser, or combinations thereof.

According to a further preferred embodiment, the device according to the invention is characterized in that the ratio of the clear diameter of the alignment element to the clear diameter at the outlet of the discharge element is in the range of 1: 1 to 1:50.

According to a further preferred embodiment, the device according to the invention is characterized in that the at least one outflow element is selected from a conically tapered tube, a nozzle, a tube constriction or combinations thereof.

According to a further preferred embodiment, the device according to the invention is characterized in that the at least one removal device is a take-up device, a rotating drum, a movable belt or a combination thereof.

According to a further preferred embodiment, the device according to the invention is characterized in that the depositing area has a perforated surface.

In the context of the present invention, a perforated surface is understood as meaning a surface which is permeable to fluid media at least in some areas. In particular, a perforated surface may be configured as perforated with slots, holes and combinations thereof.

According to a further preferred embodiment, the device according to the invention is characterized in that the at least one first and / or second profile tool has an inner cross section with a point or axisymmetric geometry or a combination of two or more identical or different point or axisymmetric geometries.

In particular, the inner cross section of the respective profile tool has an oval, in particular an elliptical or round, a triangular, a quadrangular, in particular a rectangular or square, a regular polygonal shape or any combination of said shapes. Particularly suitable are convex cross-sectional shapes or a combination of two or more convex cross-sectional shapes to a non-convex inner cross-section, such as an angular or a T-profile. Also suitable are non-convex internal cross-sectional profiles in a curved or round shape, such as a sickle-shaped or annular inner cross-section.

According to a further preferred embodiment, the device according to the invention is characterized in that the at least one application device is selected from an immersion bath, a spray applicator, an impregnation device, a spreader, a coater, a curtain applicator, transfer roll, or combinations thereof.

According to a further preferred embodiment, the device according to the invention is characterized in that the at least one fixing device is selected from a calender, a press, a forming roll, a thermal fixing device, a radiation dryer, a radiation hardener, a thermal dryer or combinations thereof.

The invention further relates to a carbon fiber tape which is obtainable by a process according to the invention and / or produced in a device according to the invention.

The carbon fiber tape according to the invention is a band- or thread-shaped carbon fiber yarn which is fixed, for example, bebindert or sizing.

In particular, it is an inventive carbon fiber tape, in which the carbon fibers and / or carbon fiber bundles are arranged unidirectionally. In this case, the carbon fibers and / or carbon fiber bundles can be arranged at least partially offset from one another. The carbon fibers and / or carbon fiber bundles may additionally or alternatively be arranged at least partially overlapping one another. For this purpose, punctiform and / or flat bonding regions are then formed between two and / or more carbon fibers and / or carbon fiber bundles.

The invention also provides the use of a carbon fiber tape which is obtainable by a process according to the invention and / or produced in a device according to the invention. It is used in particular for the production of lightweight components for the aerospace and / or automotive industry and / or in mechanical engineering, for further processing in weaving processes, laying processes, in particular for the production of carbon fibers, woven fabrics, braids, knitted fabrics, knitted fabrics, carbon fiber-containing textile structures, fabrics used for combination with non-carbon fiber materials and / or materials or combinations thereof.

In the context of the present invention, non-carbon-containing fiber materials and / or materials, fiber materials and / or materials are understood which in their composition do not contain carbon-containing organic constituent (s), which are converted by pyrolysis in graphitic carbon arranged to have.

FIGURE DESCRIPTION AND EXAMPLES

Figuren 1 - 4

zeigen verschiedene Formen von Carbonfaser-Anordnungen.

Figur 5

zeigt schematisch eine einfache Ausführungsform der erfindungsgemäßen Vorrichtung.

Figur 6

zeigt schematisch eine erfindungsgemäße Anordnung mit einem Ausströmelement.

Figur 7

zeigt eine Ausführungsform einer erfindungsgemäßen Abnahmevorrichtung.

Figur 8

zeigt schematisch eine erfindungsgemäße Ausgestaltung einer Auftrags- und Fixiervorrichtung.

The invention will be described below with reference to the FIGS. 1 to 8 explained, without being limited to these embodiments.

Figures 1 - 4

show different forms of carbon fiber assemblies.

FIG. 5

schematically shows a simple embodiment of the device according to the invention.

FIG. 6

schematically shows an inventive arrangement with a discharge element.

FIG. 7

shows an embodiment of a removal device according to the invention.

FIG. 8

schematically shows an inventive embodiment of a job and fixing device.

1

Faserverbundabfall

2

Fasergewirr bzw. Flocken

3

Einzelfaser

4

Faserbündel

5

Faserband

6

Band aus gerichteten Fasern

7

Druckluftdüse

8

Wirbelbehälterauslauf

9

Ausrichtungselement

10

Ausströmelement

11

Reduzierer

12

Wirbelgefäß bzw. Wirbelzone

13

Beschickung

15

Absaugung

16

Rotierende Trommel

17

Perforierte Oberfläche

18

Motor

20

erste Düse zur Formgebung

21

zweite Düse zur Formgebung

22

Tauchbad

23

(Umlenk-)Walzen

24

Walzenpaar

In the FIGS. 1 to 8 the following reference numbers are used:

1

Fiber composite waste

2

Fiber tangles or flakes

3

single fiber

4

fiber bundles

5

sliver

6

Band of directed fibers

7

compressed air nozzle

8th

Eddy container outlet

9

alignment member

10

outflow element

11

reducer

12

Vortex vessel or vortex zone

13

feed

15

suction

16

Rotating drum

17

Perforated surface

18

engine

20

first nozzle for shaping

21

second nozzle for shaping

22

dip

23

(Deflection) rolls

24

roller pair

The present invention is characterized in that a resolution and orientation of the carbon fiber worms and / or flakes, hereinafter referred to as flakes (2), takes place via a pneumatic process without damaging the carbon fibers. Flakes (2), which are obtained, for example, fiber composite waste (1) are fed to a vortex vessel (12). In the vortex vessel (12), the flakes (2) via a compressed air nozzle (7) with a via a reducer (11) adjustable compressed air flow is applied. Due to induced shear forces, which are caused by the turbulent flow conditions, the flakes (2) are singulated into individual fibers (3) or fiber bundles (4). The individual fibers (3) or individual fiber bundles (4) leave the vortex vessel (12) via the vortex container outlet (8). Insufficiently isolated flakes (2) are prevented due to their size at the outlet from the vortex vessel (12) via the vortex container outlet (8) and fed back to the flow by the air flow of the compressed air nozzle (7). At the vortex container outlet (8), an alignment element (9) can be connected. This leads to a largely laminar extraction flow and optimizes the alignment of the individual fibers (3) or isolated fiber bundles (4). The alignment element (9) is not limited in its design to a cylindrical body, but may also be designed to reduce the speed in a conical shape.

The individual fibers (3) or individual fiber bundles (4) emerging from the alignment element (9) or the vortex container outlet (8) are fed to a forming unit for forming the strip (4), as sketched in FIG. This consists in the case shown of a rotating drum (16), a motor (18) and an exhaust (15). The drum (16) is designed in a region (17) with a mesh fabric as a shell material to ensure a suction. The individual fibers (3) or fiber bundles (4) are deposited on the perforated surface (17) of the drum (16) through the suction (15). Alternatively, the acceptance unit can be designed as a suctioned conveyor belt. The shaped band (5) has a high degree of orientation of the individual fibers (3) or fiber bundles (4) in the fiber longitudinal direction.

In the present invention, the increase in the strength of the strip (5), which ensures its textile processability, achieved by the application of a binder according to the requirements. Alternatively, a consolidation for warranty the textile processability of the product over the application of the belt (5) are achieved with a rotation.

According to the invention, the damage-free produced sliver (5) is applied via a padding process, as outlined in Figure 8, with a suitable binder. Suitable for this purpose are, for example, aqueous systems, such as polyurethane dispersions, styrene-butadiene dispersions, epoxy dispersions or polyacrylate dispersions. It is also possible to use solutions such as PU-DMF solutions for binding the tape (5). Before and after the immersion of the strip (5), nozzles (20; 21) can be used for the purpose of shaping. Excess binder is squeezed off after the dipping process via a pair of rollers (24).

After drying of the binder, the finishing of the finished product (6) is carried out on bobbins, which can then be a textile processing, for example, a surface formation on Multiaxiallegemaschinen, fed.

The binder content in the product (6) is essentially dependent on the parameters selected in the padding process, as exemplified in FIG. 8, especially on the chosen binder and its solution concentration. Possible binder concentrations are between 0 wt.% And 99 wt.%, Preferably between 1 wt.% And 15 wt.%, Ideally between 2 wt.% And 8 wt.

Examples Example 1:

For example, a desized carbon fiber tangle is cut and presented to a mean length of 50 mm. An amount of 1.00 g carbon fibers are removed from the tangle and fed to the vortex vessel (12). The reducer (11) is set to 1 bar. About the compressed air nozzle (7) a turbulent flow is generated in the vortex vessel (12), whereby the submitted carbon fiber tangle is isolated. The individual fibers or fiber bundles emerge from the vortex vessel (12) via the vortex container outlet (8). The separated carbon fibers pass through the alignment element (9) to the acceptance unit, which is designed as a rotating drum (16). Through the suction (15) and the rotational speed of the drum (15), the isolated carbon fibers lie in the direction of rotation on the perforated region (17) of the under-sucked drum (16).

The thus prepared, 1 m long band (5) of oriented carbon fibers is padded with 5% butadiene-styrene solution, pre-dried at 100 ° C for 5 min and fixed at 175 ° C for 2 min.

A manufactured in the manner described carbon roving (6) of oriented fibers is ideal for textile fabrication and can be further processed via known processes to a fiber composite component. The test specimens produced according to DIN EN ISO 527-5 have up to 86% of the tensile modulus of the starting material and up to 90% of the original tensile strength.

Claims (15)

Process for the preparation of fiber worms for the production of semi-finished carbon fiber products, comprising the following steps: a) providing Fasergewirren at least containing carbon fibers and / or carbon fiber bundles in a swirl region; b) at least partially separating the fiber webs in a turbulent flow in the vortex region to obtain isolated carbon fibers and / or carbon fiber bundles; c) if appropriate, air classification of the singulated carbon fibers and / or carbon fiber bundles in the vortex region to obtain fractionated carbon fibers and / or carbon fiber bundles; d) discharging the separated and / or fractionated carbon fibers and / or carbon fiber bundles from the swirl region obtained in step b) into an alignment region, wherein the carbon fiber semi-finished products are obtained in or subsequent to step d). The method of claim 1, further comprising at least one of the following steps: e) aligning the carbon fibers and / or carbon fiber bundles discharged in step d) in the direction of flow of a laminar flow in the alignment region, wherein the carbon fibers and / or carbon fiber bundles are stretched along their longitudinal axis; f) outflow of the carbon fibers and / or carbon fiber bundles discharged in step d) and optionally aligned in step e) in the direction of flow of the laminar flow; g) depositing the in step d) discharged and optionally in step e) aligned in the flow direction of the laminar flow and / or optionally effluent carbon fibers and / or carbon fiber bundles obtained in step f) as a carbon fiber ribbon in a deposition area. Method according to claim 2, comprising in addition to step g) at least one of the following steps: h) layer forming the carbon fiber ribbon obtained in step g); i) profiling the carbon fiber ribbon obtained in step g); j) application of at least one binder to at least portions of the carbon fiber tape obtained in step g) with an applicator to form a at least in some areas with the at least one binder selectively and / or surface wetted carbon fiber tape; k) profiling of the carbon fiber band obtained in step j), at least in some areas with the at least one binder selectively and / or wetted surface; l) fixing the carbon fiber strip obtained in one of the steps j) or k), at least in some areas with the at least one binder, in a point-wise and / or flat-wetted manner; m) applying a size to at least portions of the carbon fiber tape obtained in step g) with an applicator. Method according to one of claims 1 to 3, wherein the turbulent flow in the vortex region in step b) is generated by means arranged in the vortex region static and / or dynamic vortex elements. Method according to the preceding claim 4, wherein the turbulent flow in the vortex region in step b) with compressed air in a range of 0.1 to 3 MPa absolute, preferably in a range of 0.15 to 2 MPa absolute, more preferably in a range of 0.2 to 1 MPa is generated absolutely. Method according to one of the preceding claims, wherein the turbulent flow in the vortex region in step b) is characterized by a Reynolds number greater than 1200. Method according to one of the preceding claims, wherein the laminar flow in the alignment region in step e) is characterized by a Reynolds number in the range of 10 to 1200. Method according to one of the preceding claims, wherein the deposition area in step g) is subjected to a force field and wherein the force field generation is selected under a negative pressure, an electric field, a magnetic field, an adhesive force or combinations thereof. Method according to one of the preceding claims, wherein no torsional force is exerted on the effluent carbon fibers and / or carbon fiber bundles obtained in step f) and / or the carbon fiber ribbon obtained in step g). Apparatus for the preparation of fiber worms for the production of semi-finished carbon fiber products, comprising: - At least one vortex container; - At least one vertebral container inlet; - At least one vortex container outlet; - At least one alignment element, wherein the alignment element is arranged in the outflow direction after the at least one vortex tank outlet; at least one outflow element, wherein the outflow element is arranged in the outflow direction downstream of the at least one alignment element, wherein the discharge element is designed such that the clear diameter is greater at its inlet than at its outlet. Device according to the preceding claim 10, characterized in that the at least one vortex tank outlet is selected from a venturi nozzle, an orifice, a bore, a flap, a pipe constriction, a valve, a slide, a diffuser or combinations thereof. Device according to one of claims 10 to 11, characterized in that the ratio of the clear diameter of the alignment element for clearing Diameter at the outlet of the discharge element in the range of 1: 1 to 1: 50. Device according to one of claims 10 to 12, characterized in that the at least one outflow element is selected from a tapered pipe, a nozzle, a pipe constriction or combinations thereof. Carbon fiber tape, obtainable by a method according to one of claims 1 to 9 and / or produced in a device according to one of claims 10 to 13, wherein the carbon fibers and / or carbon fiber bundles are unidirectional, at least partially offset from one another and / or at least partially overlapping each other and wherein between two and / or more carbon fibers and / or carbon fiber bundles punctiform and / or flat bonding areas are formed. Use of a carbon fiber tape, obtainable by a method according to one of claims 1 to 9, and / or produced in a device according to one of claims 10 to 13 for producing lightweight components for the aerospace and / or automotive industry and / or in mechanical engineering , for further processing in weaving processes, laying processes, in particular for the production of carbon fibers, woven fabrics, braids, knitted fabrics, knitted fabrics, carbon fiber-containing textile structures, fabrics, for combination with non-carbon fiber materials and / or materials or combinations thereof.

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