MULTI-LAYER AUTOMOTIVE PIPELINE

Description

[0001] The invention relates to a multi-layer motor vehicle pipeline, in particular for conveying fuels, wherein the pipeline has at least five layers. The multi-layer motor vehicle pipeline according to the invention is used in particular as a fuel pipeline in vehicles. The motor vehicle pipeline can also be used as a vent line in tank ventilation systems. In this case, the pipeline is exposed in particular to fuel vapors and their condensates.

[0002] EP 1 574 330 A1 discloses a multilayer structure that can be used for fuel tanks or fuel pipes. The multilayer structure comprises at least two polyamide layers and an intermediate EVOH layer.

[0003] EP 2 772 354 A1 discloses a multilayer fuel pipeline comprising an EVOH barrier layer. The barrier layer is sandwiched between two polyamide layers.

[0004] Multi-layer automotive pipelines of the type mentioned above are known in practice in various designs. Many of these known pipelines have the disadvantage that the pipeline layers are exposed to undesirable leaching of layer components when fuels are conveyed through them. This primarily affects the inner layer in contact with the fuel, but also the adjacent middle layers. The inner layers often contain small amounts of oligomers that can be washed out by the fuel and then precipitate in the fuel system. There, they can cause problems, particularly at nozzles and the like. The known pipelines leave much to be desired with regard to their fuel resistance or resistance to the fuels. Not least for this reason, the barrier properties of these known pipelines do not meet all requirements.Attempts have already been made to solve this problem by varying the layers—particularly the inner layers. However, improvements in reducing unwanted leaching have come at the expense of the mechanical and / or thermal resistance of the pipes. Furthermore, many of these known pipes are expensive to manufacture due to the choice of materials. This is especially true for automotive pipes with inner layers made of fluoropolymers, particularly ETFE. ETFE also has the disadvantage of producing dangerous or harmful fluorine compounds in the event of a fire.

[0005] In contrast, the invention is based on the technical problem of providing a multi-layer automotive pipeline of the type mentioned above, which avoids the disadvantages described above, offers improved chemical resistance and resistance to leaching, as well as sufficient mechanical strength and optimal resistance to various temperatures, especially higher temperatures. Furthermore, this pipeline should be as cost-effective to manufacture as possible.

[0006] To solve the technical problem, the invention teaches a multi-layer motor vehicle pipeline, in particular for the transport of fuels, wherein the pipeline has at least five layers, with the following layer structure from outside to inside: an outer layer of at least one polyolefin, a carrier layer of polyamide, a barrier layer of at least one component from the group "ethylene-vinyl alcohol copolymer (EVOH), fluoropolymer", an intermediate layer, an inner layer of polyethylene, wherein the first carrier layer has a greater thickness than the barrier layer, wherein the first carrier layer has a greater thickness than the inner layer, wherein the intermediate layer is designed as a second carrier layer and consists or consists essentially of polyamide, wherein the second carrier layer has a greater thickness than the inner layer, and wherein the total layer thickness of the pipeline is 0.7 to 2.5 mm, preferably 0.8 to 2 mm, and more preferably 0.85 to 1.8 mm. A total layer thickness of the pipeline is between 0.85 and 1.7 mm.

[0007] According to the invention, the outer layer consists of polyethylene or essentially of polyethylene. It is particularly preferred that the outer layer consists of HDPE or essentially from HDPE - It is recommended that the thickness of the outer layer be 5% to 60%, preferably 7% to 45%, and more preferably 10% to 40% of the total wall thickness of the pipeline. It is within the scope of the invention that the thickness of the outer layer be a maximum of 0.4 mm and preferably in the range between 0.1 and 0.4 mm, very preferably in the range between 0.2 and 0.4 mm.

[0008] A particularly recommended embodiment of the invention is characterized in that at least one adhesion promoter layer, and preferably an adhesion promoter layer, is interposed between the outer layer and the carrier layer. Preferably, an adhesion promoter layer based on polyamide or a polyolefin is used. If an adhesion promoter layer based on polyamide is used, it is recommended to be a modified polyamide, preferably a modified polyamide based on polyamide 612. If an adhesion promoter layer based on a polyolefin is used, it is preferably a polyolefin, in particular polyethylene, modified with a carboxylic acid derivative, preferably with a maleic acid derivative, and very preferably with maleic anhydride.- The thickness of the adhesion promoter layer is advantageously 3% to 30%, preferably 5% to 20%, and most preferably 5% to 15% of the total wall thickness of the pipeline. The thickness of the adhesion promoter layer is advantageously 0.03 to 0.15 mm and preferably 0.03 to 0.1 mm.

[0009] A highly recommended embodiment of the invention is characterized in that the carrier layer consists of polyamide 6 or essentially of polyamide 6. In principle, the first carrier layer can also consist of or essentially consist of at least one polyamide from the group "polyamide 612, polyamide 12, polyamide 10, polyamide 11, co-polyamide 6 / 6.6, co-polyamide 6 / 12." It is within the scope of the invention that the thickness of the carrier layer is 5% to 70%, preferably 10% to 60%, and more preferably 15% to 60% of the total wall thickness of the pipeline. The thickness of the carrier layer is expediently at least twice as thick and preferably at least three times as thick as the thickness of the adhesion promoter layer. It is recommended that the thickness of the carrier layer be 0.1 to 0.8 mm, preferably 0.1 to 0.75 mm, and more preferably 0.2 to 0.6 mm.According to a proven embodiment of the invention, the carrier layer is thicker than the barrier layer and preferably at least twice as thick as the barrier layer. According to one embodiment of the invention, the carrier layer is at least 2.5 times as thick as the barrier layer. It is within the scope of the invention for the carrier layer to be thicker than the outer layer and is recommended to be at least 1.5 times thicker than the outer layer.

[0010] One embodiment of particular importance within the scope of the invention is characterized in that the barrier layer consists of ethylene-vinyl alcohol copolymer (EVOH) or essentially of EVOH. This material has proven particularly useful as a barrier layer in combination with the other layers according to the invention. It is within the scope of the invention that the thickness of the barrier layer is 5% to 50%, preferably 5% to 45%, and more preferably 10% to 40% of the total wall thickness of the pipeline. The thickness of the barrier layer is expediently 0.05 to 0.4 mm, preferably 0.05 to 0.3 mm, and more preferably 0.75 to 0.25 mm.

[0011] A preferred embodiment of the invention is characterized in that the intermediate layer consists of polyamide 6 or essentially of polyamide 6. In principle, the second carrier layer can also consist of or essentially consist of at least one or more polyamides from the group "polyamide 612, polyamide 12, polyamide 10, polyamide 11, co-polyamide 6 / 6.6, co-polyamide 6 / 12". Within the scope of this preferred embodiment, the intermediate layer takes on the function of a second carrier layer. With regard to this embodiment, the carrier layer explained above is also referred to below as the first carrier layer and the intermediate layer as the second carrier layer. It is within the scope of the invention that the thickness of the intermediate layer or the second carrier layer is 5% to 70%, preferably 10% to 60% and more preferably 15% to 60% and very preferably 15% to 55% of the total wall thickness of the pipeline. The thickness of the intermediate layer orthe second carrier layer 0.1 to 0.8 mm, preferably 0.1 to 0.75 mm, and more preferably 0.2 to 0.6 mm. It is recommended that the intermediate layer or the second carrier layer be thicker than the barrier layer and preferably at least twice as thick as the barrier layer. According to one embodiment of the invention, the intermediate layer or the second carrier layer is at least 2.5 times as thick as the barrier layer. Furthermore, it is within the scope of the invention that the intermediate layer or the second carrier layer is thicker than the outer layer and preferably at least 1.5 times thicker than the outer layer.

[0012] According to a further preferred embodiment of the invention, the intermediate layer is designed as an adhesion promoter layer between the barrier layer and the inner layer. This is preferably an adhesion promoter layer based on a polyamide and / or an adhesion promoter layer based on a polyolefin. In the embodiment with the adhesion promoter layer between the outer layer and the first carrier layer, this adhesion promoter layer then forms a second adhesion promoter layer in the pipeline according to the invention. The same advantageously applies to this second adhesion promoter layer as to the first adhesion promoter layer described above. The embodiments described there then also apply to the second adhesion promoter layer between the barrier layer and the inner layer. This particularly applies to the material of the adhesion promoter layer and / or the thickness of the adhesion promoter layer.

[0013] According to the invention, the inner layer consists of polyethylene or essentially of polyethylene. In a very preferred embodiment, which is of particular importance within the scope of the invention, the inner layer consists of HDPE or essentially of HDPE (high-density polyethylene). This material has proven particularly suitable for solving the technical problem. This inner layer acts as a barrier layer against the components of the fuel or fuel vapor flowing through the pipeline and is characterized by very little leaching of layer components. It is within the scope of the invention that the thickness of the inner layer is 5% to 55%, preferably 7% to 50% and more preferably 10% to 40% of the total wall thickness of the pipeline. The thickness of the inner layer is expediently 0.05 to 0.45 mm, preferably 0.05 to 0.4 mm and more preferably 0.1 to 0.35 mm.It is within the scope of the invention that the thickness of the inner layer is less than the thickness of the carrier layer. According to one embodiment of the invention, the inner layer is designed as an electrically conductive layer and is provided with conductive additives.

[0014] If, according to the invention, the intermediate layer consists of or essentially consists of polyamide (second carrier layer), it is further within the scope of the invention for this intermediate layer or second carrier layer to have a greater thickness than the barrier layer. The first carrier layer and / or the second carrier layer is expediently at least 1.2 times, preferably at least 1.5 times, and more preferably at least 1.8 times thicker than the barrier layer.

[0015] The first carrier layer and / or the second carrier layer is expediently at least 1.2 times and preferably at least 1.4 times and more preferably at least 1.5 times thicker than the inner layer. - It is within the scope of the invention for the outer layer to be thicker than the barrier layer. Preferably, the outer layer is at least 1.1 times and more preferably at least 1.2 times thicker than the barrier layer. - According to a recommended embodiment of the invention, the first carrier layer and / or the second carrier layer is thicker than the outer layer. Preferably, the first carrier layer and / or the second carrier layer is at least 1.2 times and more preferably at least 1.3 times thicker than the outer layer.

[0016] It is within the scope of the invention that the outer layer ensures optimal protection against environmental influences. Firstly, it is corrosion-resistant and chemically resistant to splash water, especially salt water, as well as chemically resistant to oil and fuel. The two carrier layers ensure, in particular, the mechanical stability of the pipeline according to the invention. Like the barrier layer, the inner layer has a barrier effect, particularly against the components of the fuel or fuel vapor flowing through the pipeline.

[0017] According to a preferred embodiment of the invention, the automotive pipeline according to the invention is manufactured by extrusion or coextrusion of the layers. With the layer components according to the invention, very simple coextrusion is possible and, above all, coextrusion can be carried out at moderate temperatures. The pipeline according to the invention can also be designed as a smooth, unprofiled pipe or as a corrugated pipe.

[0018] The invention is based on the finding that the automotive pipeline according to the invention exhibits excellent chemical resistance and, above all, is resistant to leaching of layer components. This applies primarily to the inner layer but also to the adjacent layers. The pipeline according to the invention exhibits optimal barrier properties as well as very good fuel and aging resistance. A particular advantage is that one and the same pipeline according to the invention can be used for various fuels and offers the aforementioned advantages over these different fuels. It should be emphasized that, in addition to the chemical resistance described, the pipeline according to the invention also exhibits excellent mechanical strength.Furthermore, the pipeline according to the invention is characterized by optimal thermal resistance and can be used without problems in a temperature range between -40°C and 140°C. Compared to many previously known pipelines, the pipeline according to the invention is also very cost-effective or can be manufactured from very inexpensive materials. It should also be emphasized that the materials of the layers of the pipeline according to the invention are very easy to process and, above all, a simple and problem-free coextrusion of the layer sequence according to the invention is possible.

[0019] The invention is explained in more detail below using an exemplary embodiment: According to one embodiment of the invention, the outer layer consists of HDPE or essentially of HDPE and expediently has a layer thickness of 0.2 to 0.4 mm. According to a preferred embodiment, an adhesion promoter layer, which preferably consists of or essentially consists of a polyolefin modified with maleic anhydride - in particular polyethylene - and preferably has a layer thickness of 0.03 mm to 0.1 mm, is directly adjacent to the inside of the outer layer. The first carrier layer, which consists of polyamide 6 or essentially of polyamide 6 and is recommended to have a layer thickness of 0.2 mm to 0.75 mm, is directly adjacent to the inside of the adhesion promoter layer. The barrier layer, which consists of EVOH or essentially of EVOH and preferably has a layer thickness of 0.05 to 0.3 mm, is directly adjacent to the inside of the first carrier layer.Directly adjacent to the barrier layer on the inside is the intermediate layer, which in this embodiment is designed as an adhesion promoter layer and consists or essentially consists of a maleic anhydride-modified polyolefin, in particular polyethylene. This intermediate layer or second adhesion promoter layer preferably has a layer thickness between 0.2 and 0.75 mm. Directly adjacent to the second carrier layer on the inside is the inner layer, which consists or essentially consists of HDPE and preferably has a layer thickness of 0.1 to 0.4 mm. The total wall thickness of this pipeline is expediently between 0.8 and 2 mm.

[0020] The invention is explained in more detail below with reference to a drawing that represents only one exemplary embodiment. The drawing shows a schematic representation: Fig. 1 a perspective view of a pipeline and Fig. 2 a section through the object according to Fig. 1 .

[0021] In the exemplary embodiment according to the figures, the pipeline 1 has an outer layer 2 which consists of polyamide 12 or essentially of polyamide 12 and preferably has a layer thickness of between 0.2 and 0.4 mm. On the inside, this outer layer 2 is followed by an adhesion promoter layer 3 which preferably and in the exemplary embodiment consists of polyamide 612 modified with maleic anhydride. On the inside, this is followed by the first carrier layer 4 which preferably and in the exemplary embodiment consists of polyamide 6 or essentially of polyamide 6 and expediently has a layer thickness of between 0.2 and 0.75 mm. On the inside, this first carrier layer 4 is followed by the barrier layer 5 which preferably and in the exemplary embodiment consists of EVOH or essentially of EVOH and recommended has a layer thickness of between 0.1 and 0.3 mm.Adjoining this barrier layer 5 on the inside is the intermediate layer 6 in the form of a second carrier layer, which consists of polyamide 6 or essentially polyamide 6 and preferably has a layer thickness between 0.2 and 0.75 mm. Adjoining the intermediate layer 6 on the inside is the inner layer 7, which consists of HDPE or essentially HDPE and preferably has a layer thickness between 0.1 and 0.4 mm. The multi-layer automotive pipeline 1 shown in the figures was produced by coextrusion. It is within the scope of the invention that the inner layer 7 can be provided with conductive additives.

Claims

1. Multi-layer motor vehicle pipeline (1), in particular for transporting fuels, wherein the pipeline (1) comprises at least five layers, with the following layer structure from outside to inside: - an outer layer (2) made of at least one polyolefin, - a first support layer (4) made of polyamide, - a barrier layer (5) made of at least one component from the group "EVOH, fluoropolymer," - an intermediate layer (6), - an inner layer (7) made of polyethylene, wherein the first support layer (4) has a greater thickness than the barrier layer (5), wherein the first support layer (4) has a greater thickness than the inner layer (7), wherein the intermediate layer (6) is designed as a second support layer and consists or substantially consists of polyamide, wherein the intermediate layer has a greater thickness than the inner layer (7) and wherein the total layer thickness of the pipeline (1) is 0.7 to 2.5 mm, preferably 0.8 to 2 mm and preferably 0.85 to 1.8 mm.

2. Pipeline according to claim 1, wherein the outer layer consists of polyethylene, in particular of HDPE, or consists substantially of polyethylene, in particular substantially of HDPE.

3. Pipeline according to either of claims 1 or 2, wherein the thickness of the outer layer is 5% to 60%, preferably 7% to 45% of the total wall thickness of the pipeline (1),4. Pipeline according to any of claims 1 to 3, wherein at least one adhesive layer (3), preferably one adhesive layer (3), is interposed between the outer layer (2) and the first support layer (4).

5. Pipeline according to claim 4, wherein the thickness of the adhesive layer (3) is 3% to 30%, preferably 5% to 20% of the total wall thickness of the pipeline (1).

6. Pipeline according to any of claims 1 to 5, wherein the first support layer (4) consists of polyamide 6 or substantially of polyamide 6.

7. Pipeline according to any of claims 1 to 5, wherein the first support layer (4) consists or substantially consists of at least one or of a polyamide from the group "polyamide 612, polyamide 12, polyamide 10, polyamide 11, co-polyamide 6 / 6.6, co-polyamide 6 / 12."8. Pipeline according to any of claims 1 to 7, wherein the thickness of the first support layer (4) is 5% to 70%, preferably 10% to 60% and preferably 15% to 60% of the total wall thickness of the pipeline (1).

9. Pipeline according to any of claims 1 to 8, wherein the thickness of the barrier layer (5) is 5% to 50%, preferably 10% to 40% of the total wall thickness of the pipeline (1).

10. Pipeline according to any of claims 1 to 9, wherein the intermediate layer (6) consists of polyamide 6 or substantially of polyamide 6.

11. Pipeline according to any of claims 1 to 10, wherein the intermediate layer (6) or the second support layer (6) consists or substantially consists of at least one or of a polyamide from the group "polyamide 612, polyamide 12, polyamide 10, polyamide 11, co-polyamide 6 / 6.6, co-polyamide 6 / 12."12. Pipeline according to any of claims 1 to 11, wherein the thickness of the intermediate layer (6) is 5% to 70%, preferably 10% to 60% and preferably 15% to 60% of the total wall thickness of the pipeline (1).

13. Pipeline according to any of claims 1 to 12, wherein the intermediate layer (6) is designed as an adhesive layer and is preferably an adhesive layer based on a polyamide or an adhesive layer based on a polyolefin.

14. Pipeline according to any of claims 1 to 13, wherein the inner layer (7) consists of HDPE or substantially of HDPE.

15. Pipeline according to any of claims 1 to 14, wherein the thickness of the inner layer is 5% to 55%, preferably 7% to 50% and preferably 10% to 40% of the total wall thickness of the pipeline (1).

16. Pipeline according to any of claims 1 to 15, wherein the outer layer (2) has a greater thickness than the barrier layer (5).

17. Pipeline according to any of claims 1 to 16, wherein the pipeline is manufactured by coextrusion.