Pipe fitting for air brake conduit

Abstract

The fitting 1 for guiding compressed air includes an inner layer 2, an internal adhesion promoter layer 3, and a carrier layer 4. The internal adhesion promoter layer 3 is disposed between the carrier layer 4 and the inner layer 2, wherein the carrier layer 4 comprises PA6 and the inner layer 2 comprises polyamide. The internal adhesion promoter layer 3 comprises a first polyamide and a second polyamide, wherein the first polyamide in the internal adhesion promoter layer 3 is PA12.

Description

Technical Field

[0001] This invention relates to pipe fittings, particularly pipe fittings for guiding compressed air, comprising an inner layer, an internal adhesion promoter layer, and a carrier layer, wherein the internal adhesion promoter layer is disposed between the carrier layer and the inner layer, wherein the carrier layer comprises PA6, wherein the inner layer comprises polyamide, wherein the internal adhesion promoter layer comprises a first polyamide, and wherein the internal adhesion promoter layer comprises a second polyamide. The invention also relates to the use of such pipe fittings. Background Technology

[0002] The fittings for an air brake duct are known in US 2009 / 0065085 A1 and comprise a total of five layers. The inner layer (0.15 mm) has impact-modified PA12 containing a plasticizer. An inner adhesion promoter layer (0.1 mm) attached to the inner layer comprises approximately 62 wt% PA6.12, 16 wt% PA6, and an additional 8 wt% plasticizer (BBSA) and 11 wt% impact modifier. The adhesion promoter layer is surrounded by a relatively thick carrier layer (0.5 mm) having 87 wt% PA6 and 12 wt% plasticizer (BBSA). This is followed by an outer adhesion promoter layer (0.1 mm) having the exact same composition as the inner adhesion promoter layer. Finally, the outer layer (0.15 mm) comprises the exact same composition as the inner layer.

[0003] The disadvantage of such known tubing is that it is exposed to fluctuating high air pressures (>25 bar) and, in particular, there is a risk of delamination. Therefore, the basic objective of this invention is to provide tubing that is particularly stable under pressure, has a low manufacturing cost, and is also free from delamination tendency at the aforementioned pressures. Summary of the Invention

[0004] This objective is achieved by a conduit for guiding compressed air, the conduit comprising an inner layer, an inner adhesion aid layer, and a carrier layer, wherein the inner adhesion aid layer is disposed between the carrier layer and the inner layer, wherein the carrier layer comprises PA6, wherein the inner layer comprises polyamide, wherein the inner adhesion aid layer comprises a first polyamide, wherein the inner adhesion aid layer comprises a second polyamide, characterized in that the first polyamide of the inner adhesion aid layer is PA12.

[0005] This invention is based on the understanding that PA6 is a very pressure-resistant and inexpensive plastic, making it ideal as a carrier layer for compressed air conduits. However, PA6 is less chemically stable than, for example, PA12, making PA12 more suitable as an inner and / or outer layer compared to PA6. Since PA6 only adheres insufficiently to PA12, US 2009 / 0065085 A1 resorts to internal and external adhesion aid layers.

[0006] It has been found that air brake ducts operating under high pressure place extremely stringent requirements on their components due to continuous pressure fluctuations throughout the vehicle's lifespan. The present invention recognizes that the long-term pressure resistance of existing components under automotive conditions (potentially very low and very high temperatures, as well as significant chemical loads from salt, oil, fuel, etc.) still needs improvement. Delamination, particularly between the inner or outer layer and the corresponding adhesive layer, is especially likely to occur after several years due to material aging, continuous pressure fluctuations within the components, and vibrations within the vehicle.

[0007] This invention is particularly based on the understanding that delamination can be counteracted by incorporating PA12 into the inner adhesion aid layer. It has been found that when the inner layer comprises PA12, PA11, and / or PA6.12, PA12 in the inner adhesion aid layer is responsible for providing excellent adhesion to the inner layer. This is unexpected because in the prior art, PA6.12 is the main component in the adhesion aid layer, and due to the monomer of PA12, PA6.12 adheres very well to the PA12, PA11, and PA6.12 inner layers. However, the inclusion of PA12 in the inner adhesion aid layer further improves adhesion.

[0008] Finally, it has been discovered that, theoretically, the internal adhesion aid layer can be designed to have sufficient adhesion through appropriate additives to improve adhesion. However, such additives require special adaptation to both the adhesion aid layer and the surrounding layers, which is a costly and relatively expensive process. Due to the small thickness of the internal adhesion aid layer, this process, or such different compositions of the layers, is uneconomical, and therefore this variant is ruled out. The mixture of two polyamides proposed in this invention is significantly more economical. The result is that the objectives described at the outset are achieved.

[0009] The inner layer is preferably the innermost layer of the fitting and is in contact with the medium transported by the fitting. Conveniently, the inner layer defines the lumen of the fitting. The inner layer and / or the inner adhesion aid layer and / or the carrier layer and / or the outer adhesion aid layer and / or the outer layer are preferably (each) integrally formed and particularly homogeneously formed.

[0010] The term "homogeneous" preferably refers to a layer derived from only one melt or extruded from only one extrusion nozzle. The term "homogeneous" preferably means that the composition of the homogeneous body is the same or substantially the same in all locations. An interface is preferably present between two (homogeneous) layers. The fitting is preferably integrally formed and, in particular, composed of multiple homogeneous layers. The term "integral" preferably means that the integral piece can only be converted into multiple pieces in an irreversible or destructive manner.

[0011] According to a particularly preferred embodiment, the second polyamide of the inner adhesion aid layer is PA6.12, wherein the weight percentage of the second polyamide or PA6.12 in the inner adhesion aid layer is less than 70, 60, 50, 40, 30, or 20%. This achieves a sufficiently high proportion of PA6.12 in the inner adhesion aid layer, thereby achieving particularly good adhesion to the inner layer. Advantageously, the weight percentage of PA6.12 in the inner adhesion aid layer is at least 10, 20, or 30% by weight.

[0012] The weight percentage of the first polyamide or PA12 in the internal adhesion aid layer is preferably at least 30, 40, 50, 60, 70, or 80%. Advantageously, the weight percentage of the first polyamide or PA12 in the internal adhesion aid layer is at most 90, 80, 70, 60, 50, 40, or 30%.

[0013] Very preferably, the inner layer comprises an aliphatic polyamide, preferably an aliphatic polyamide having more than 6 or 9 carbon atoms per repeating unit. The inner layer advantageously contains PA12 and / or PA11 and / or PA6.12 and / or PA10.10 and / or PA10.12 and / or PA6.10. This chemically separates the carrier layer from the medium in the lumen or the fitting. Oil or humid air in the lumen can particularly adversely affect the carrier layer or PA6 in the carrier layer, and the inner layer protects the carrier layer from such effects. The inner layer may include plasticizers and / or impact modifiers. Very preferably, the proportion of polyamide, or one or more aliphatic polyamides, or the proportion comprising PA12 and / or PA11 and / or PA6.12 and / or PA10.10 and / or PA10.12 and / or PA6.10, is at least 20, 30, 40, 50, 60, 70, or 80% by weight of the inner layer. Advantageously, the proportion of polyamide or one or more aliphatic polyamides or the proportion of PA12 and / or PA11 and / or PA6.12 and / or PA10.10 and / or PA10.12 and / or PA6.10 is at most 99 or 97 or 95% by weight of the inner layer.

[0014] According to a highly preferred embodiment, the thickness of the carrier layer is at least 0.6, 0.7, or 0.8 mm. This achieves higher compressive strength in the fitting. It also results in the carrier layer playing a mechanically dominant role within the fitting. Preferably, the thickness of the carrier layer is at most 3.0, 2.5, or 2.0 mm. Most preferably, the ratio of the carrier layer thickness to the wall thickness of the fitting is at least 0.4, 0.5, 0.6, or 0.7. Advantageously, the ratio is at most 0.95, 0.9, 0.85, or 0.8.

[0015] Advantageously, the carrier layer has a polyamide or PA6 proportion of at least 20, 30, 40, 50, 60, 70, 80, or 90% by weight. Preferably, the carrier layer has a polyamide or PA6 proportion of up to 99, 97, or 95% by weight.

[0016] Conveniently, the internal adhesion aid layer adheres to the inner layer and / or the carrier layer. This achieves good adhesion. It also minimizes the number of layers in the fitting. Preferably, the thickness of the internal adhesion aid layer is at most 0.30, 0.25, 0.20, 0.15, 0.10, or 0.08 mm. Conveniently, the internal adhesion aid layer surrounds the inner layer. Preferably, the carrier layer surrounds the internal adhesion aid layer.

[0017] Preferably, the fitting includes an outer layer, wherein the outer layer advantageously comprises an aliphatic polyamide, preferably an aliphatic polyamide having more than 6 or 9 carbon atoms per repeating unit. The outer layer advantageously contains PA12 and / or PA11 and / or PA6.12 and / or PA10.10 and / or PA10.12 and / or PA6.10. This protects the carrier layer from environmental influences, particularly from water, salt, oil, fuel, etc. Possibly, the outer layer includes plasticizers and / or impact modifiers. Advantageously, the proportion of polyamide, or one or more aliphatic polyamides, or the proportion comprising PA12 and / or PA11 and / or PA6.12 and / or PA10.10 and / or PA10.12 and / or PA6.10, is at least 20, 30, 40, 50, 60, 70, or 80% by weight of the outer layer. Advantageously, the proportion of polyamide or one or more aliphatic polyamides or the proportion of PA12 and / or PA11 and / or PA6.12 and / or PA10.10 and / or PA10.12 and / or PA6.10 is at most 99 or 97 or 95% by weight of the outer layer.

[0018] Preferably, the fitting includes an external adhesion promoter layer. This achieves good adhesion between the carrier layer and the outer layer. Conveniently, the external adhesion promoter layer is disposed between the outer layer and the carrier layer. Advantageously, the external adhesion promoter layer is abutted against the carrier layer and / or the outer layer. Conveniently, the external adhesion promoter layer surrounds the carrier layer. Preferably, the outer layer surrounds the external adhesion promoter layer. Very preferably, the thickness of the external adhesion promoter layer is at most 0.30 or 0.25 or 0.20 or 0.15 or 0.10 or 0.08 mm. Preferably, the external adhesion promoter layer comprises a first polyamide. Advantageously, the external adhesion promoter layer comprises a second polyamide.

[0019] Preferably, the first polyamide in the external adhesion aid layer is PA12. The weight percentage of the first polyamide or PA12 in the external adhesion aid layer is preferably at least 30, 40, 50, 60, 70, or 80%. More preferably, the weight percentage of the first polyamide or PA12 in the external adhesion aid layer is at most 90, 80, 70, 60, 50, 40, or 30%.

[0020] According to a particularly preferred embodiment, the second polyamide of the external adhesion aid layer is PA6.12, wherein the weight percentage of the second polyamide or PA6.12 in the external adhesion aid layer is less than 60, 50, or 40%. Advantageously, the weight percentage of the second polyamide or PA6.12 in the external adhesion aid layer is at least 10, 20, or 30% by weight. This achieves a relatively high proportion of PA12 in the external adhesion aid layer, thereby achieving particularly good adhesion to the outer layer.

[0021] Preferably, the wall thickness of the fitting is at least 0.8, 0.9, or 1.0 mm. This allows for higher compressive strength. Preferably, the wall thickness of the fitting is at most 3.5, 3.0, or 2.5 mm.

[0022] Advantageously, the inner and / or outer layer has a layer thickness of at most 0.40, 0.30, 0.20, or 0.15 mm. This makes the carrier layer the mechanically dominant layer within the fitting, thereby substantially limiting the inner and / or outer layer to its chemical function. The inner and / or outer layer advantageously has a layer thickness of at least 0.05, 0.07, or 0.09 mm.

[0023] The objective stated at the outset is achieved by using the fittings according to the invention preferably inside a vehicle as fittings for guiding compressed air, and in particular as fittings for air brake ducts.

[0024] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. In the accompanying drawings... Attached Figure Description

[0025] Figure 1 A perspective view of a fitting for an air brake duct according to the present invention is shown. Detailed Implementation

[0026] Figure 1 The figure shows a three-dimensional diagram of a fitting 1 for an air brake duct used in a vehicle. The layers 2-6 are shown sequentially, but this is merely for better illustration. Fitting 1 in this embodiment must withstand pressure fluctuations exceeding 25 bar and is constructed for automotive applications, exposing it to the corresponding climate over a relatively long service life.

[0027] In this embodiment, the fitting 1 preferably comprises five layers. The fitting 1 has an inner layer 2 that defines a cavity 7 within the fitting 1, such that the inner layer 2 contacts the medium within the fitting 1. The medium is compressed air with fluctuating humidity due to climate, wherein the compressed air may contain contaminant components to a small extent. These contaminant components may in particular be substances such as oil, which may be used within an effective pneumatic circulation.

[0028] The fitting 1 includes an inner adhesive layer 3 and a carrier layer 4. The inner adhesive layer 3 is disposed between the inner layer 2 and the carrier layer 4, such that the carrier layer 4 surrounds the inner adhesive layer 3. The fitting 1 preferably includes an outer layer 6 and, more preferably, an outer adhesive layer 5. The outer adhesive layer 5 is preferably disposed between the carrier layer 4 and the outer layer 6.

[0029] The carrier layer 4 conveniently comprises polyamide, and preferably PA6. The weight percentage of polyamide or PA6 in the carrier layer 4 is preferably at least 50, 60, or 70% by weight. The carrier layer 4 may have at least one additive, such as an additive for improving impact toughness (impact modifier).

[0030] Particularly preferably, the carrier layer 4 has a thickness of at least 0.8 or 1.0 mm. In this embodiment, the ratio of the thickness of the carrier layer 4 to the wall thickness of the pipe 1 is at least 0.6 or 0.7. In this embodiment, the carrier layer 4 is the mechanically dominant layer of the pipe 1.

[0031] The inner layer 2 in this embodiment may have PA12 and / or PA11 and / or PA6.12. The inner layer 2 particularly preferably comprises only polyamide, i.e., PA12. Very preferably, the proportion of polyamide in the inner layer 2 is at least 60 or 70% by weight. Advantageously, the inner layer 2 may include plasticizers and / or impact modifiers. The layer thickness of the inner layer 2 is advantageously at most 0.2 or 0.15 mm.

[0032] The internal adhesion aid layer 3 contains PA12, and preferably PA6.12. More preferably, PA12 accounts for at least 50 or 60% by weight of the internal adhesion aid layer 3. PA6.12 accounts for at most 50 or 40% by weight of the internal adhesion aid layer 3. Particularly preferably, the internal adhesion aid layer 3 has a layer thickness of at most 0.15, 0.12, 0.10, or 0.08 mm.

[0033] The outer layer 6 of this embodiment may have PA12 and / or PA11 and / or PA6.12. The outer layer 6 particularly preferably comprises only polyamide, i.e., PA12. Very preferably, the polyamide content of the outer layer 6 is at least 60 or 70% by weight. Advantageously, the outer layer 6 may include plasticizers and / or impact modifiers. The layer thickness of the outer layer 6 is advantageously at most 0.2 or 0.15 mm.

[0034] The external adhesion aid layer 5 has PA12, and preferably PA6.12. Most preferably, PA12 accounts for at least 50 or 60% by weight of the external adhesion aid layer 5. PA6.12 accounts for at most 50 or 40% by weight of the external adhesion aid layer 5. Particularly preferably, the external adhesion aid layer 5 has a layer thickness of at most 0.15, 0.12, 0.10, or 0.08 mm.

[0035] List of reference numerals

[0036] 1. Pipe fittings

[0037] 2 Inner layer

[0038] 3. Internal Adhesion Additive Layer

[0039] 4. Carrier layer

[0040] 5. External Adhesion Aid Layer

[0041] 6 Outer layer

[0042] 7. Lumen

Claims

1. A fitting (1), particularly a fitting (1) for guiding compressed air, the fitting comprising an inner layer (2), an internal adhesion aid layer (3), and a carrier layer (4), wherein the internal adhesion aid layer (3) is disposed between the carrier layer (4) and the inner layer (2), wherein the carrier layer (4) comprises PA6, wherein the inner layer (2) comprises polyamide, wherein the internal adhesion aid layer (3) comprises a first polyamide, and wherein the internal adhesion aid layer (3) further comprises a second polyamide, characterized in that, The first polyamide in the internal adhesion aid layer (3) is PA12.

2. The fitting (1) according to claim 1, wherein the second polyamide of the inner adhesion aid layer (3) is PA6.12, wherein the weight proportion of PA6.12 in the inner adhesion aid layer (3) is less than 60% or 50% or 40%.

3. The fitting (1) according to claim 1 or 2, wherein the inner layer (2) comprises an aliphatic polyamide, preferably an aliphatic polyamide having more than 6 or 9 carbon atoms per repeating unit, more preferably PA12 and / or PA11 and / or PA6.12 and / or PA10.10 and / or PA10.12 and / or PA6.

10.

4. The pipe fitting (1) according to any one of claims 1 to 3, wherein the thickness of the carrier layer (4) is at least 0.6 or 0.7 or 0.8 mm.

5. The fitting (1) according to any one of claims 1 to 4, wherein the inner adhesive layer (3) is abutted against the inner layer (2) and / or the carrier layer (4).

6. The fitting (1) according to any one of claims 1 to 5, wherein the fitting (1) comprises an outer layer (6), wherein the outer layer (6) preferably comprises an aliphatic polyamide, preferably an aliphatic polyamide having more than 6 or 9 carbon atoms per repeating unit, more preferably PA12 and / or PA11 and / or PA6.12 and / or PA10.10 and / or PA10.12 and / or PA6.

10.

7. The fitting (1) according to any one of claims 1 to 6, wherein the fitting (1) has an external adhesive layer (5).

8. The pipe fitting (1) according to any one of claims 1 to 7, wherein the wall thickness of the pipe fitting (1) is at least 0.8 or 0.9 or 1.0 mm.

9. The fitting (1) according to any one of claims 1 to 8, wherein the inner layer (2) and / or the outer layer (5) have a layer thickness of up to 0.4 or 0.3 or 0.2 mm.

10. The pipe fitting (1) according to any one of claims 1 to 9 is used for guiding compressed air, preferably for guiding compressed air inside a vehicle, and especially for use as a pipe fitting for an air brake conduit.

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