Tube body with a flame-retardant layer

Abstract

The present invention relates to a tubular body 1, the tubular body 1 comprising a flame retardant layer 2 and an outer layer 3, the outer layer 3 surrounding the flame retardant layer 2, the flame retardant layer 2 containing a thermoplastic synthetic substance and expanded graphite fine particles, the expanded graphite fine particles being formed to expand at a temperature equal to or higher than the starting temperature, the expanded graphite fine particles being in a non-expanded state, and the outer layer 3 having a thermoplastic synthetic substance. In the above tubular body, the average roughness value Ra of the outer surface of the tubular body 1 or the outer surface of the outer layer 3 is at most 200 μm or 100 μm or 50 μm, which is characterized in that.

Description

Technical Field

[0001] The present invention relates to a tubular body, which comprises a flame-retardant layer and an outer layer, wherein the outer layer surrounds the flame-retardant layer, the flame-retardant layer contains a thermoplastic synthetic substance and expanded graphite microparticles, and the outer layer has a thermoplastic synthetic substance. The present invention also relates to a fluid conduit in this manner, and the use of this tubular body or this fluid conduit.

Background Art

[0002] Tubular bodies of this type are known from Patent Document 1, where - according to each embodiment - a flame-retardant layer or a reinforcing layer constitutes the outermost layer. The reinforcing layer contains fibers, and these fibers can be made of, for example, aramid or be glass fibers. These fibers are joined to each other to form a fabric and, accordingly, a non-uniform layer, and this fabric protects the underlying flame-retardant layer. The flame-retardant layer enables the tubular body to withstand fire or heat for several seconds or minutes, or longer. The flame-retardant layer has a thickness of about 1.5 mm and contains expanded graphite, and the microparticles of this expanded graphite have an average particle size ranging from 0.2 mm to 0.4 mm. This tubular body is inserted into a conduit connector by frictional engagement.

[0003] However, the ability for particularly long-life fluid connections is disadvantageous in known tubular bodies. It has been found that there are points to be improved in the mechanical connection between a known tubular body and a conduit connector belonging to this tubular body - especially in a demanding ambient environment such as, for example, in an onshore vehicle. In particular, the vibrations of a land vehicle can, over the years, potentially loosen the engagement due to friction between the pipe body and the conduit connector. In contrast, the increasing brittleness of the pipe body material also contributes, and thus this factor also correspondingly weakens the engagement due to friction over the years. On the other hand, this brittleness is the result of high temperatures or temperature fluctuations acting on the pipe body, especially with respect to a land vehicle or within this land vehicle, in addition to normal material degradation. In short, a land vehicle is exposed to humidity and thus to sea salt and other such things, which can similarly have negative consequences for the engagement due to friction between the pipe body and the conduit connector.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Therefore, the problem underlying the present invention is to provide a pipe body, which can form a particularly long - life or tough connection with a conduit connector, even under the adverse circumstances, especially in the case of a land vehicle, and which can withstand heat for as long as possible in case of a fire.

Means for Solving the Problems

[0006] This problem is solved by a pipe body comprising a flame - retardant layer and an outer layer, wherein the outer layer surrounds the flame - retardant layer, the flame - retardant layer contains a thermoplastic synthetic substance and expanded graphite microparticles, these expanded graphite microparticles are formed to expand at a temperature above the starting temperature, and the expanded graphite microparticles are in an unexpanded state. The outer layer has a thermoplastic synthetic substance, The average roughness value Ra of the outer surface of the tube body or the outer surface of the outer layer is at most 200 μm or 100 μm or 50 μm.

Advantages of the Invention

[0007] The present invention is firstly based on the recognition that welding of the tube body to the conduit connector enables a clearly better or longer - life connection of both of these components. It has been found that a flame - retardant layer having expanded graphite, as well as the fabric layer and the associated heterogeneous layer, are not suitable for welding to the conduit connector.

[0008] The present invention is further based on the recognition that known flame - retardant layers having expanded graphite have an overly large surface roughness or an overly large average roughness value. Thus, the fine particles of expanded graphite generate a significant roughness, and this significant roughness greatly increases defective products, especially during an advantageous and fine laser - welding connection between the tube body and the conduit connector. Therefore, for laser - welding connections, it is a great advantage that the surfaces joined to contact each other form an engagement according to an actually ideal shape, and thus the surrounding weld seams are actually consistent during all possible connections between the tube body and the conduit connector.

[0009] Furthermore, for laser - welding connections, the material of the conduit connector or the material of the tube body should be sufficiently transparent for the laser beam, while the materials of the components located inside each should sufficiently absorb this laser beam. At the same time, automobile manufacturers usually require conduit connectors and tube bodies colored black. Special coloring substances satisfy the requirements for transparency for the laser beam (near - infrared) on the one hand and for the black appearance within the visible light spectrum on the other hand. However, these special coloring substances are prohibitively expensive, and for this reason, these special coloring substances are used especially in conduit connectors. Therefore, the amount of material of the conduit connector 5 is less in most cases than the amount of material of the pipe body.

[0010] The present invention is based on the recognition that the pipe body is inserted particularly advantageously into the conduit connector, and thus, advantageously, the outer surface of the pipe body is welded to the inner surface of the conduit connector. It has been found that a small average roughness value on the outside of the pipe body enables particularly good bonding, in particular welding bonding, and very particularly laser welding bonding. This is advantageously achieved by the outer layer having, in some cases, small particles and / or the thermoplastic composite material of the outer layer being advantageously formed homogeneously. A non-homogeneously formed composite material is, for example, a fabric layer or a foam material. The layer arrangement of the pipe body according to the invention thereby enables a heat-resistant pipe body, which enables a particularly long-lasting connection with the conduit connector. As a result, the problem described at the beginning is solved.

[0011] The concept "average roughness value" preferably means the arithmetic average roughness value according to DIN EN ISO 4287:2010 and DIN EN ISO 4288:1998. For the detection of the measurement section, the measuring device is guided along the circumferential direction of the pipe body, and for this purpose, in some cases, a plurality of circulations displaced in the axial direction are carried out, or, however, a helical path is taken.

[0012] According to a very advantageous embodiment, the outer layer is within the cross-section of the pipe body having particles or hollow chambers or filled hollow chambers with a radially average expansion of up to 200 μm or 150 μm or 100 μm or 50 μm, or having no particles or hollow chambers or filled hollow chambers at all. This contributes to a small average roughness value. For this determination, a tubular body piece, for example 10 mm in length, is examined, in particular by means of micro-CT (μCT). As long as 100 or 50 or 20 or less than 10 particle / hollow chambers or filled hollow chambers with an expansion in the radial direction of 5 μm or 2 μm or 1 μm are found, the criterion "no particles at all" is thus considered to be met.

[0013] According to a very advantageous embodiment, the thermoplastic composite material of the outer layer is formed homogeneously over the entire cross-section of this outer layer. This improves the weldability of the outer layer. The concept "homogeneously" preferably means a structure having exactly one intentionally created interface, one inner and one outer, within one cross-section. Individual, very small cavities (e.g. in the submillimeter range) are not intentional, for example. In contrast, the foam has intentional air bubbles and, accordingly, an inner interface. Similarly, the added particles are intentionally added particles, so that also in the case of added particles, a number of intermediate interfaces can be found between the inner and the outer interfaces of the layer. If this thermoplastic composite material has the form of a fabric or a fabric layer, the thermoplastic composite material of the outer layer is likewise not formed almost homogeneously over the entire cross-section of this outer layer.

[0014] The same also applies if the outer layer in the form of a fabric is additionally penetrated by yet another composite material on top of it. As long as the shaped material (vergossene Material) and the fabric material are considered as the connecting composite material formation for which particles or hollow chambers or filled hollow chambers are defined with respect to its composite material formation, the fabric layer thus penetrated does not have any kind of particles or hollow chambers or filled hollow chambers. It is possible for the microparticles or the filled hollow chambers to be made of a material different from the synthetic material. These microparticles can, in particular, have mineral properties, while the filled hollow chambers can, in particular, contain a gas - in particular air. In the case of a complete absence of microparticles or hollow chambers or filled hollow chambers, there may in that case, however, still be a porous synthetic material layer filled by yet another synthetic material. This includes, in particular, a fabric layer penetrated by a thermoplastic synthetic material. Such a layer does not, in that case, however, contain a thermoplastic synthetic material formed homogeneously across the entire cross - section of this outer layer. - Advantageously according to μCT images - If up to 100 or 50 or 20 structures having a size of at least 5 μm or 2 μm or 1 μm are found inside a 10 - mm - long tube section, the thermoplastic synthetic material is advantageously formed homogeneously.

[0015] It is particularly advantageous for the tube to be integrally formed. Purposefully, the outer layer is irreversibly bonded to the flame - retardant layer, directly or indirectly via the interposition of one or more layers. Along with this, the individual layers of the tube are firmly bonded to each other and the corresponding mechanical stability is ensured. For the inspection of the irreversible bonding of the layers of the tube, purposefully, an intermediate section of this tube is inspected under the separation of possible conduit connectors in some cases. For example, if the outer protective tube can be pulled out of the tube, the layer or layers of this protective tube do not belong to the tube or inner tube located therein. It is possible, for example, for the tube or inner tube to be integrally bonded to the conduit connector in terms of material structure, while the outer protective tube is not integrally bonded to the tube in terms of material structure, but is probably bonded to the conduit connector. In these cases, basically, similarly, the outer protective tube and the tube or inner tube are indirectly integrally connected to each other in terms of material structure through this conduit connector or these conduit connectors. In the intermediate section piece of the arbitrarily taken out tube, the tube is integral in the case in question here only when the layers can be separated from each other only irreversibly and in a manner that causes them to break accordingly under the separation of the conduit connector. For example, when the tube or inner tube with the outer protective tube is cut off from the conduit connector, this tube is not integrally formed in any case where the protective tube can be manually pulled out from the tube or inner tube and, advantageously, pushed in again.

[0016] According to an advantageous embodiment, the outer layer is the outermost layer of the tube, which is - in particular integral. It is possible for an integral tube or inner tube to have an outer layer and at the same time be surrounded by a protective tube that is pushed in. In that case, the outer layer of the tube or inner tube is also the outermost layer of the integral tube or inner tube at the same time. This is because the protective tube can be pulled out from the tube or inner tube in the case of separation of the conduit connector.

[0017] Particularly advantageously, the flame-retardant layer has a layer thickness of at most 1.5 mm or 1.0 mm or 0.7 mm or 0.5 mm. This avoids the tube becoming overly thick and, accordingly, overly inflexible during the bending to be performed. It is advantageous for the layer thickness of the flame-retardant layer to be at least 0.05 mm or 0.07 mm or 0.10 mm. This avoids layer peeling.

[0018] It is extremely advantageous for the outer layer to have a layer thickness of at least 0.06 mm or 0.08 mm or 0.10 mm. If not, there is a possibility that the flame retardant layer is torn during extrusion based on the expanded graphite microparticles, and as a result, the flame retardant layer is not formed to cover in a planar shape. Advantageously, the layer thickness of the outer layer is at most 1.0 mm or 0.8 mm or 0.6 mm. This avoids the tube body from becoming excessively thick and, accordingly, becoming excessively inflexible during the bending to be performed. It is extremely advantageous that the layer thickness of the outer layer is formed so as to compensate for the unevenness of the flame retardant layer located thereunder. Advantageously, the total layer thickness of the outer layer and the flame retardant layer is at least 0.15 mm or 0.2 mm or 0.25 mm or 0.3 mm. Appropriately, the total layer thickness from the layer thickness of the flame retardant layer and the layer thickness of the outer layer reaches at most 2.0 mm or 1.5 mm or 1.0 mm.

[0019] Advantageously, the weight percentage of the expanded graphite microparticles in the flame retardant layer is at least 1 wt% concentration (Gew.-%) or 3 wt% concentration or 5 wt% concentration or 7 wt% concentration or 9 wt% concentration. Appropriately, the weight percentage of the expanded graphite microparticles in the flame retardant layer reaches at most 50 wt% concentration or 40 wt% concentration or 30 wt% concentration. It has been found that an excessively large weight percentage of the expanded graphite microparticles induces an excessively large unevenness or an excessively large brittleness.

[0020] According to an advantageous embodiment, the expanded graphite microparticles in the flame retardant layer have an average height in the radial direction of at most 200 μm or 150 μm or 100 μm or 70 μm within the cross section of the tube body. This achieves that the average roughness value on the outer surface of the tube body or the outer surface of the outer layer does not become excessively large. Advantageously, the expanded graphite microparticles in the flame retardant layer have an average height in the radial direction of at least 10 μm or 20 μm or 30 μm within the cross section of the tube body. In particular, this ensures that the expansion rate of the expanded graphite particles does not become excessively small.

[0021] It is advantageous that the expanded graphite particles of the flame retardant layer have an onset temperature of at least 130 °C or 150 °C or 170 °C or 190 °C or 210 °C or 230 °C. Purposefully, the onset temperature of the expanded graphite particles is coordinated, in particular, with the melting temperature of the thermoplastic synthetic material of the flame retardant layer. Advantageously, the onset temperature of the expanded graphite particles is at least 10 °C or 20 °C or 30 °C higher than the melting temperature of the thermoplastic synthetic material of the flame retardant layer 2.

[0022] Advantageously, the expansion rate of the expanded graphite particles of the flame retardant layer is at least 10 cm 3 / g or 20 cm 3 / g or 30 cm 3 / g. Advantageously, the expansion rate of the expanded graphite particles of the flame retardant layer reaches a maximum of 350 cm 3 / g or 250 cm 3 / g or 200 cm 3 / g or 150 cm 3 / g. An extremely large expansion rate requires such expanded graphite particles, and it has been found that the magnitude of the expansion rate of these expanded graphite particles is excessively large with respect to the layer thickness of the tubular body. The present invention is based, in particular, on the recognition that an expansion rate of 100 cm 3 / g is, on the one hand, sufficient for intumescence and, on the other hand, enables sufficiently small expanded graphite particles.

[0023] It is advantageous that the tubular body contains a secondary flame retardant, which preferably acts to dilute the gas or dilute the oxygen, and the secondary flame retardant is preferably an inorganic flame retardant. In this way, it can be achieved that the flame-retardant layer is additionally assisted by the auxiliary flame retardant correspondingly or synergistically, or even further thereon. It is particularly advantageous that the auxiliary flame retardant contains ammonia and includes, for example, ammonium phosphate, ammonium sulfate, and / or ammonium polyphosphate. It is possible for the auxiliary flame retardant to be present in the flame-retardant layer and / or the outer layer. Particularly preferably, the auxiliary flame retardant is contained only in the flame-retardant layer.

[0024] Purposefully, the tubular body further comprises at least one, preferably one, other inner layer. This allows for a complex tubular structure. It is possible for the tubular body to have a plurality of other inner layers. Preferably, the flame-retardant layer surrounds at least one inner layer. It is possible for the flame-retardant layer to be adjacent to at least one of the inner layers. It is also possible for at least one other inner layer to be integrally combined with the flame-retardant layer in terms of material structure. This inner layer can be the innermost layer. It is possible to arrange another one or a plurality of other layers between the innermost layer and the flame-retardant layer. Preferably, a separation layer is arranged between the inner layer and the flame-retardant layer, and in this case, this separation layer is preferably used for the spatial separation of the flame-retardant layer and the inner layer.

[0025] Preferably, at least one inner layer contains a thermoplastic synthetic substance. This ensures coextrusion even in the case of at least one inner layer. The thermoplastic synthetic substance of at least one other inner layer can be polyamide, polyester, polyolefin, polyurethane, or a thermoplastic elastomer. It is possible for the polyester to be particularly polyethylene terephthalate (PET). It is possible that a barrier layer is disposed between yet another inner layer and the flame retardant layer. It is possible that this barrier layer contains, for example, ethylene vinyl alcohol copolymer (EVOH) or a fluoropolymer. It is advantageous that one or more separation layers are disposed between the barrier layer or the inner layer and the flame retardant layer.

[0026] It is advantageous that the tubular body is manufactured, at least in part and preferably completely, by coextrusion.

[0027] It is possible that the thermoplastic synthetic substance of the flame retardant layer and / or the thermoplastic synthetic substance of the outer layer is polyamide, polyester, polyolefin, polyurethane, a thermoplastic elastomer, or a blend of the aforementioned synthetic substances. As the polyester, PET is particularly worthy of consideration.

[0028] According to a highly advantageous embodiment, the thermoplastic synthetic substance of the outer layer contains a thermoplastic elastomer, preferably a thermoplastic vulcanizate, and particularly preferably Santoprene. The thermoplastic vulcanizate contains ethylene propylene diene rubber (EPDM) microparticles in a matrix made of polypropylene. It is highly advantageous that the thermoplastic synthetic substance of the flame retardant layer is a polyolefin and preferably polypropylene. According to an advantageous embodiment, the tubular body comprises two and preferably only two inner layers. Preferably, the innermost layer contains a thermoplastic synthetic substance, preferably a thermoplastic elastomer, more preferably a thermoplastic vulcanizate, and particularly preferably Santoprene. It is highly advantageous that the second inner layer is disposed between the innermost layer and the flame retardant layer and is a separation layer. It is advantageous that the separation layer has a thermoplastic synthetic substance, preferably a polyolefin, and particularly preferably polypropylene. It is particularly advantageous if all layers of the tube body have a common synthetic material, preferably polypropylene. The common synthetic material of all layers preferably serves to particularly well prevent the layer composite from delamination. The polypropylene material is particularly suitable as a barrier material against aqueous solutions, for example water-glycol solutions, and thus the polypropylene composite is particularly suitable as a heat exchanger tube body.

[0029] Advantageously, the fluid conduit comprises at least one tube body according to the invention as described above and at least one conduit connector. Advantageously, it is advantageous if the tube body and at least one of the conduit connectors are welded to each other. This provides, in particular, a long-life and fluid-tight connection. Advantageously, the conduit connector contains a thermoplastic synthetic material. It is particularly advantageous if the thermoplastic synthetic material of the conduit connector is a synthetic material consisting of the group "polyamide, polyester, polyolefin, polyurethane, thermoplastic elastomer" or a blend consisting of two or more synthetic materials of the aforementioned group. Advantageously, the synthetic material of the conduit connector belongs to the same group of synthetic materials as the thermoplastic synthetic material of the outer layer and / or the inner layer. For example, if the thermoplastic synthetic material of the outer layer is polyamide, the thermoplastic synthetic material of the conduit connector is preferably also polyamide. Most particularly advantageously, the thermoplastic synthetic material of the conduit connector and the thermoplastic synthetic material of the outer layer and / or the inner layer belong to the same synthetic material type PA6 or PA11 or PA12. It is possible for the thermoplastic synthetic material of the conduit connector to be supplied from the same material storage container as the thermoplastic synthetic material of the outer layer and / or the inner layer.

[0030] It is most particularly advantageous if the tube body and the conduit connector are welded to each other and, preferably, are joined to each other by laser welding. It is possible for the tube body and the conduit connector to be joined to each other by rotary friction welding or mirror welding. Advantageously, the tube body is inserted into the coupling portion of the conduit connector. It is possible for the tube body to be inserted into the coupling portion of the conduit connector. Suitably, the coupling portion has at least one weld seam extending around it. It is possible for the coupling portion to have two or more weld seams extending around it. The coupling portion of the conduit connector has inner and outer weld seams, and it is possible for these weld seams to couple the coupling portion of the conduit connector to the tube body.

[0031] The conduit connector advantageously has a connection body. The connection body is advantageously formed integrally, and particularly advantageously, integrally formed. The term "integrally" advantageously means manufacture from a single injection molding. The connection body advantageously has a connection portion for a mating member to be connected to the conduit connector. The mating member is suitably a plug, and this plug is inserted into the conduit connector. The connection body is advantageously formed such that the mating member can be inserted - advantageously reversibly - into the connection portion. The connection body advantageously has one or more connection portions for connection to the tube body. The connection portions are formed for the insertion and / or attachment of the tube body. For example, if the connection portion is formed as a groove extending around it, the tube body is simultaneously inserted against the inner wall of the groove extending around it and inserted into the outer wall of this groove extending around it.

[0032] It is possible for the conduit connector to particularly have a retainer. The retainer is, for example, formed substantially in a U-shape and has one U-shaped base portion and two U-shaped leg portions. According to one embodiment, it is possible for the retainer to be formed to extend completely around. It is possible that the mating member has a locking element, and this locking element is formed, for example, as a collar extending around or as a groove extending around. Advantageously, the locking element of the mating member or the plug is locked by the retainer of the conduit fitting throughout the insertion of this mating member 9 into this conduit fitting. According to one embodiment, it is possible that the connecting body is composed of two members and has a coupling member and a connecting member. It is possible that the coupling member and the connecting member are coupled to each other via a locking joint or a torsional joint. The conduit fitting expediently comprises a sealing material. It is possible that the sealing material has, for example, one sealing ring or two sealing rings made of an elastic material.

[0033] The problem mentioned at the beginning is solved by the use of a tube or a fluid conduit according to the invention in a land vehicle and in particular in an electric vehicle. The tube or fluid conduit is advantageously used for cooling, particularly advantageously for cooling the battery of an electric vehicle drive. It is particularly advantageous that a tube or fluid conduit is used for guiding an aqueous solution and in particular a water-glycol solution. The tube or fluid conduit is used, for example, as a supply conduit for a tube system of the battery of an electric vehicle drive. It is extremely particularly advantageous that the tube or fluid conduit is formed such that it maintains the cooling of the battery of the electric vehicle drive for several seconds or minutes longer than a conventional tube or fluid conduit without a flame-retardant layer, and thus, correspondingly, a lot of time remains for the passengers of the vehicle to evacuate or be rescued. In that case, the cooling of the battery of the electric vehicle is particularly important. This is because an excessively high temperature of the battery induces the battery to burn up more and more quickly.

[0034] The tube according to the invention or the fluid conduit according to the invention is schematically illustrated below on the basis of the figures of the embodiments.

Brief Description of the Drawings

[0035]

Figure 1

Figure 2

Figure 3

Figure 4a

Figure 4b

Figure 4c

DETAILED DESCRIPTION OF THE INVENTION

[0036] The tubular body according to the present invention comprises four layers 2, 3, 26, 27 according to the embodiment shown in FIG. 1, these layers surrounding the inner diameter 8 of the tubular body. The tubular body 1 has a flame-retardant layer 2 and an outer layer 3, and furthermore, two inner layers 4. In this embodiment, the flame-retardant layer 2 is joined to the outer layer 3 and the inner layer 4 by coextrusion, in an engagement state by material respectively. The inner layers 4, 26 form the inner layer 26 of the tubular body 1 in this embodiment, and this inner layer is separated from the flame-retardant layer 2 by an advantageous separation layer 27. In FIG. 1, possible protective tubular bodies are not shown, these protective tubular bodies being configured, for example, as corrugated tubular bodies and surrounding the tubular body 1 without being directly joined to it in an engagement state by material. In this embodiment, the outer layer 3 is the outermost layer of the integrally formed tubular body 1.

[0037] Advantageously, all layers 2, 3, 26, 27 of the tube body 1 contain a thermoplastic synthetic substance. It is possible for the flame-retardant layer 2 to have polypropylene, in particular isotactic polypropylene. The separating layer 27 contains, in this embodiment, polypropylene and advantageously isotactic polypropylene. In this embodiment, the outer layer 3 and the inner layer 26 have a thermoplastic vulcanizate, in particular Santoprene. Advantageously, the material of the inner layer 26 is supplied from the same material storage container as the material of the outer layer 3.

[0038] Since the thermoplastic vulcanizate also has polypropylene, all layers of the tube body 1 of this embodiment contain polypropylene, and for this reason, a good material structure integral bond between the four layers 2, 3, 26, 27 of the tube body 1 is achieved. Furthermore, the polypropylene composite of the tube body 1 is particularly well suited for guiding aqueous solutions - in particular water - glycol solutions. Polypropylene hardly contains water and is thereby more resistant to water compared to, for example, more expensive polyamides. The tube of this embodiment is, in particular, a supply conduit for a tube system of a drive battery of an electric vehicle.

[0039] According to the invention, the flame-retardant layer 2 contains expanded graphite microparticles, which is suggested in FIG. 1. The expanded graphite microparticles are advantageously formed in flakes and are embedded in the polypropylene of the flame-retardant layer 2. In this embodiment, the weight fraction of the expanded graphite microparticles in the flame-retardant layer 2 is at least 10%. It is possible for the expanded graphite microparticles to have an average thickness of, for example, 25 μm. Based on the flake-like shape, the surface of the expanded graphite microparticles basically has an upper surface and a lower surface, and these upper and lower surfaces can extend along several 100 μm in both dimensions. When the expanded graphite microparticles are sieved, for example, 85% of the microparticles can fall through a mesh width of the inner diameter of 180 μm (85% of the microparticles are finer than 80 mesh). The expanded graphite of this example expands by 100 cm 3 / g at 1000 °C.

[0040] The melting temperature of the isotactic propylene in layer 2 and layer 27 is 185 °C. The melting temperature of the thermoplastic vulcanizate of the outer layer 3 and the inner layer 26 reaches 165 °C. This means that in order to still avoid the expansion of the expanded graphite microparticles throughout the tubular extrusion molding, the starting temperature of the expanded graphite microparticles in this example should be adjusted to about 190 to 200 °C.

[0041] In this example, the outer surface of the outer layer 3 has an average roughness value Ra of 50 μm. This average roughness value Ra is induced particularly by the expanded graphite microparticles in the flame retardant layer 2, however, it is partially averaged by the thermoplastic composite material in this flame retardant layer 2. Because the thermoplastic composite material of the flame retardant layer 2 also serves as a filler material in this flame retardant layer 2. The non-flatness of the flame retardant layer 2 is further averaged by the outer layer 3, and this outer layer is formed microscopically homogeneously in this example, and in particular, it does not have bubbles or microparticles exceeding a maximum particle extension of 1 μm. It is advantageous that the layer thickness of the flame retardant layer 2 is about 200 μm. The layer thickness of the outer layer 3 reaches 250 μm. The layer thickness of the separation layer 27 is 150 μm in this example. The layer thickness of the inner layer 26 reaches 150 μm.

[0042] The tubular body 1 shown in FIG. 1 is connected to the fluid conduits 1, 5 via welding joints 7, 18 by means of a conduit connector 5 in accordance with FIG. 2. The conduit connector 5 comprises a connecting body 11 which, in this embodiment, is preferably made of one piece and, more preferably, is integrally formed and manufactured by injection molding from a thermoplastic synthetic material - preferably polypropylene. Since the thermoplastic vulcanizate of the outer layer 3 and the inner layer 26 also contains polypropylene, this results in particularly good welding joints 7, 18. The connecting body 11 expediently comprises a connecting portion 14 and a joining portion 15. In this embodiment, the welding joints 7, 18 are arranged in the region of the joining portion 15. The welding joints 7, 18 comprise an outer weld seam 7 and an inner weld seam 18. In this embodiment, both weld seams 7, 18 are produced by rotary friction welding, during which the tubular body 1 is inserted into the tubular body receiving portion 17 of the conduit connector 5 or the joining portion 15.

[0043] The tubular body receiving portion 17 is expediently axially limited by an abutment portion 13 and is preferably configured as a circumferentially extending, ring-shaped groove. The tubular body receiving portion 17 in particular has an outer wall portion 20 and an inner wall portion 21. The inner wall portion 21 of this embodiment tapers in the axial inward direction and, accordingly, in the direction of the tubular body 1 at the outer surface of this tubular body, so that the tubular body 1 can be pushed into the inner wall portion 21 particularly easily. The taper of the inner wall portion 21 is relatively pronounced in FIG. 2 and can be formed clearly weaker in other embodiments.

[0044] During the process of rotary friction welding, the inserted tubular body 1 is preferably held while the conduit connector 5 is rotated. This rotation is rapid enough for the frictional heat generated to be sufficient within the tubular body receiving portion 17 to melt the material at the interface. As a result, in particular, an outer weld seam 7 and an inner weld seam 18 are formed. Further additional weld seams, not shown here, are generated directly at the groove bottom of the pipe body receiving part 17 or at the abutment part 13. It is important for the formation of clean weld seams 7, 18 that the unevenness of the expanded graphite particles of the flame retardant layer 2 is compensated by the inner layer 4 and the outer layer 3.

[0045] In the embodiment according to FIG. 2, the connecting body 11 comprises a fluid passage 10 which connects the connecting part 15 to the connecting portion 14. The connecting part 15 has, in particular, an axial extension corresponding to the overlapping portion of the pipe body 1 and the connecting body 11 in the axial direction. In the longitudinal sectional view according to FIG. 2, the mating member 9 is inserted into the conduit connector 5 or into the connecting portion 14. The mating member 9 is the tip of a further pipe body 1 not shown, or, however, of a connecting element of a mechanism unit, for example a tank / pump / valve / battery. It is possible for the mating member 9 to have a locking element 23, which can advantageously be formed as a collar extending around, but equally as a groove extending around.

[0046] As exemplarily shown in FIG. 3, the conduit connector 5 expediently comprises a retainer 16. This retainer 16 is basically configured in a U-shape, in particular in a front view, and has two legs 25. The legs 25 are connected to each other via a U-shaped base part which forms an operating part 24. The retainer 16 can be inserted radially into the connecting body 11 or the connecting portion 14 of FIG. 2 by manual pressing on the operating part 24. When the mating member 9 is then inserted axially into the conduit connector 5, the locking element 23 of the mating member 9 elastically spreads the legs 25 of the retainer 16 away from each other. As soon as the locking element 23 passes through the leg portion 25 of the retainer 16, the leg portion 25 snaps back based on elastic return energy, whereby the mating member 9 is fixed within the conduit connector 5.

[0047] In addition, the conduit connector 5 has a sealing material 12, which in this embodiment comprises two sealing rings and a spacer located therebetween. The insertion shaft portion 22 of the mating member 9 is formed such that frictional engagement with the sealing material 12 is generated for the purpose, whereby a fluid-tight seal is achieved. The sealing material 12 is fixed in particular by a sealing material holder 19, and thus the sealing material 12 is also fixed in the direction outside the axis. In this embodiment, the inner wall of the connecting body 11, the insertion shaft portion 22 of the mating member 9, and the coupling portion 15 are formed concentrically with each other together with the pipe body 1 connected to this coupling portion, and have a common central axis M. In other embodiments, it is possible that the coupling portion 15 and the connecting portion 14 are formed by being bent with respect to each other.

[0048] In FIG. 4, three modified examples A to C of still another welded joint portions 6 and 21 between the pipe body 1 and the conduit connector 5 are shown. In the case of FIG. 4A, the coupling portion 15 of the conduit connector 5 has a pipe body receiving portion 17, into which the pipe body 1 is inserted. Different from FIG. 2, the pipe body receiving portion 17 does not have an inner wall portion, but rather has only an outer wall portion 20 and an abutting portion 13. Based on the absence of the inner wall portion of the pipe body receiving portion 17, therefore, no inner weld seam is generated, but rather only the single weld seam 6 is generated. The single weld seam 6 can be produced, for example, using rotary friction welding.

[0049] In FIG. 4B, yet another embodiment of the welded joint 21 between the tube body 1 and the conduit connector 5 is shown. In this example, the joint portion 15 includes a tube receiving portion 17, which does not have an outer wall portion, but instead has an inner wall portion 21. The inner wall portion 21 is formed in a tapered shape in the direction (Errichtung) towards the inside of the axis on the outer surface of this inner wall portion. Therefore, when the tube body 1 is pushed in, the tip portion of the tube body 1 expands more and more, forming an engagement due to increasing friction. The tube body 1 is also pushed in this example until it reaches the abutting portion 13 of the conduit connector 5 or the joint portion 15 or the tube receiving portion 17. A weld seam 6 can be generated by rotary friction welding.

[0050] In FIG. 4C, the joint portion 15 includes a tube receiving portion 17, which is basically formed in a hollow cylindrical shape and is terminated by the abutting portion 13. The tube receiving portion 17 is particularly configured such that the inner wall portion of the tube body 1 is flush and transitions into the inner wall portion 21 of the conduit connector 5. In this example, the material of the conduit connector 5 or the joint portion 15 is formed to be transparent based on a special coloring substance additive with respect to a laser beam, particularly a near-infrared laser beam. However, it is colored black within the visible spectrum. In contrast, the material of the tube body 1 is opaque with respect to the same laser beam. Therefore, these laser beams are absorbed at the interface between the outer surface of the tube body 1 and the inner surface of the tube receiving portion 17. The tube body 1 is also preferably colored dark or black using a conventional pigment, so that a uniform, colorful appearance of the fluid conduits 1, 5 is achieved. At the same time, the laser beam can only pass through within the tube receiving portion 17 up to the tube body 1.

[0051] This laser beam or these laser beams can be guided so as to generate a complete circulation, whereby a correspondingly circulating weld joint 6 is achieved. Since these laser beams are formed relatively finely and only an engagement due to a medium-strength friction between the tubular body 1 and the conduit connector 5 is generated, an outer surface of the tubular body 1 or, in particular, a uniform surface of the outer layer 3 is advantageous. The average roughness value of the outer surface of the tubular body 1 according to this embodiment shown in FIG. 4C is, particularly preferably, less than 50 μm and, for example, 20 μm. Thereby, a particularly long-life, fluid coupling between the tubular body 1 and the conduit connector 5 is generated, and the tubular body 1 simultaneously has particularly good flame retardancy.

Explanation of Reference Numerals

[0052] 1 Tubular body 2 Flame-retardant layer 3 Outer layer 4 Inner layer 5 Conduit connector 6 Only weld joint 7 Outer weld joint 8 Inner diameter of the tubular body 1 9 Counterpart member 10 Fluid passage of the conduit connector 5 11 Connection body of the conduit connector 5 12 Sealing material of the conduit connector 5 13 Contact portion of the conduit connector 5 14 Connection portion of the connection body 11 15 Coupling portion of the connection body 11 16 Retainer of the conduit connector 5 17 Tubular body accommodating portion of the connection body 11, coupling portion 15 18 Inner weld joint 19 Sealing material holder of the conduit connector 5 20 Outer wall portion 21 Inner wall portion 22 Insertion shaft portion of the counterpart member 9 23 Locking element of the counterpart member 9 24 Operating portion of the retainer 16 25 Leg portion of the retainer 16 26 Inner layer 27 Separation layer 1 Fluid conduit 5 Fluid conduits M Central axis 6 Weld joint 7 Weld joint 18 Weld joints

Claims

1. A pipe body (1), wherein the pipe body (1) comprises a flame-retardant layer (2) and an outer layer (3), the outer layer (3) surrounds the flame-retardant layer (2), the flame-retardant layer (2) contains a thermoplastic synthetic substance and expanded graphite fine particles, these expanded graphite fine particles are formed to expand at a temperature above the starting temperature, the expanded graphite fine particles are in a non-expanded state, the outer layer (3) has a thermoplastic synthetic substance, in the above pipe body, the average roughness value Ra of the outer surface of the pipe body (1) or the outer surface of the outer layer (3) is at most 200 μm or 100 μm or 50 μm, characterized in that the pipe body (1).

2. The outer layer (3) has, within the cross-section of the pipe body (1), particles or hollow chambers having an average expansion in the radial direction of at most 200 μm or 150 μm or 100 μm or 50 μm, or has no particles or hollow chambers or filled hollow chambers at all, characterized in that the pipe body (1) according to claim 1.

3. The thermoplastic synthetic substance of the outer layer (3) is characterized in that it is uniformly formed over the entire cross-section of the outer layer (3), the pipe body (1) according to claim 1.

4. The pipe body (1) is characterized in that it is integrally formed, the pipe body (1) according to any one of claims 1 to 3.

5. The outer layer (3) is the outermost layer of the pipe body (1), the pipe body (1) according to any one of claims 1 to 4.

6. The flame-retardant layer (2) has a layer thickness of at most 1.0 mm or 0.7 mm or 0.5 mm, the pipe body (1) according to any one of claims 1 to 5.

7. The outer layer (3) has a layer thickness of at least 0.05 mm or 0.07 mm, the pipe body (1) according to any one of claims 1 to 6.

8. The weight percentage of the expanded graphite fine particles in the flame-retardant layer (2) is at least 1 wt% concentration or 3 wt% concentration or 5 wt% concentration, the pipe body (1) according to any one of claims 1 to 7.

9. The expanded graphite fine particles in the flame retardant layer (2) have an average height in the radial direction of at most 200 μm, or 150 μm, or 100 μm within the cross section of the tubular body (1), and the tubular body (1) according to any one of claims 1 to 8 is characterized thereby.

10. The expanded graphite fine particles of the flame retardant layer (2) have an onset temperature of at least 130 °C, or 150 °C, or 170 °C, and the tubular body (1) according to any one of claims 1 to 9 is characterized thereby.

11. The expansion ratio of the expanded graphite fine particles in the flame retardant layer (2) is at least 10 cm ３ / g or 20 cm ３ / g or 30 cm ３ / g, and the tubular body (1) according to any one of claims 1 to 10 is characterized in that.

12. The tubular body (1) contains a secondary flame retardant, and this secondary flame retardant preferably acts to dilute the gas or dilute the oxygen, and the tubular body (1) according to any one of claims 1 to 11 is characterized in that the secondary flame retardant is preferably an inorganic flame retardant.

13. The tubular body (1) further comprises at least one, preferably one, inner layer (4), and preferably the flame retardant layer (2) surrounds this inner layer (4), and preferably the flame retardant layer (2) is adjacent to at least one of the inner layers (4), and the tubular body (1) according to any one of claims 1 to 12 is characterized thereby.

14. The thermoplastic synthetic material of the flame retardant layer (2) and / or the thermoplastic synthetic material of the outer layer (3) contains polyamide, polyester, polyolefin, polyurethane, or a thermoplastic elastomer, and the tubular body (1) according to any one of claims 1 to 13 is characterized thereby.

15. A fluid conduit, comprising at least one tubular body (1) according to any one of claims 1 to 14 and at least one conduit connector (5), and preferably the tubular body (1) and at least one of the conduit connectors (5) are welded to each other, and the fluid conduit (1) is characterized thereby.

16. Especially for cooling, preferably for cooling the battery of an electric vehicle drive unit, Use of the tubular body (1) according to any one of claims 1 to 14, or of the fluid conduit according to claim 15, in a land vehicle, especially in an electric vehicle.

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