Multilayer tube for guiding fuel fluid and method of manufacturing same

Abstract

A multilayer tube for guiding fuel fluid or brake fluid. The multilayer tube comprises an outer protection layer, a barrier layer radially within the outer protection layer, an intermediate layer radially within the barrier layer, and an inner layer radially within the intermediate layer. At least two of the layers are co-extruded layers. Each of the barrier layer and the inner layer comprises a partially aromatic polyamide.

Claims

1. A multilayer tube for guiding fuel fluid or brake fluid, comprising: an outer protection layer; a barrier layer radially within the outer protection layer; an intermediate layer radially within the barrier layer; and an inner layer radially within the intermediate layer; wherein at least two of the layers are co-extruded layers, and wherein each of the barrier layer and the inner layer comprises a partially aromatic polyamide, and wherein the partially aromatic polyamide is PA-MXD6 which is an aliphatic polyamide resin.

2. The multilayer tube according to claim 1, wherein the outer protection layer comprises at least one of PA6, PA12, P6.12, PA6.6, PA11, PA6.10 and PPA.

3. The multilayer tube according to claim 1, wherein the outer protection layer comprises a thermoplastic elastomer.

4. The multilayer tube according to claim 1, wherein the intermediate layer comprises at least one of PA6, PA12, P6.12, PA6.6, PA11, PA6.10, PA10.10 and PPA.

5. The multilayer tube according to claim 1, wherein the intermediate layer comprises a thermoplastic elastomer.

6. The multilayer tube according to claim 1, wherein the inner layer is an electrically conductive layer.

7. The multilayer tube according to claim 1, wherein the nominal layer thickness of the inner layer is in a range from 0.05 mm to 0.2 mm.

8. The multilayer tube according to claim 1, wherein a supplemental layer is provided between the outer protection layer and the barrier layer.

9. The multilayer tube according to claim 1, wherein the inner layer and the barrier layer are directly adjacent to each other.

10. The multilayer tube according to claim 1, wherein a ratio of a nominal layer thickness of the barrier layer and of a nominal layer thickness of the inner layer is in a range from 1:0.5 to 1:2.

11. The multilayer tube according to claim 1, wherein a ratio of a nominal layer thickness of the barrier layer and of a nominal layer thickness of the intermediate layer is in a range from 1:2 to 1:10.

12. The multilayer tube according to claim 1, wherein a ratio of a nominal layer thickness of the inner layer and of a nominal layer thickness of the intermediate layer is in a range from 1:2 to 1:10.

13. A multilayer tube for guiding fuel fluid or brake fluid, comprising an outer protection layer, a barrier layer radially within the outer protection layer, an intermediate layer radially within the barrier layer, and an inner layer radially within the intermediate layer, wherein at least two of the layers are co-extruded layers, and wherein each of the barrier layer and the inner layer comprises a partially aromatic polyamide.

14. A method of manufacturing a multilayer tube, comprising the steps: providing an extrudable outer protection layer material for an outer protection layer; providing an extrudable barrier layer material for a barrier layer, wherein the barrier layer material comprises a partially aromatic polyamide; providing an extrudable intermediate layer material for an intermediate layer; providing an extrudable inner layer material for an inner layer, wherein the inner layer material comprises a partially aromatic polyamide; and co-extruding at least two of the layers.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) Exemplary embodiments of the disclosure are explained in more detail in the following description and are represented in the drawings, in which:

(2) FIG. 1 shows a schematic cross section of a multilayer tube together with a schematic view of an extruder; and

(3) FIG. 2 is a detail II of FIG. 1.

EMBODIMENTS

(4) A multilayer tube according to the disclosure is generally shown in FIG. 1 and given the reference numeral 10.

(5) The multilayer tube 10 has an outer diameter 12, for example 8.0 mm and an inner diameter 14, for example 6.0 mm.

(6) Further, the multilayer tube 10 has an outer protection layer 16. Radially within the outer protection layer, the multilayer tube 10 comprises a barrier layer 18. An intermediate layer 20 is provided radially within the barrier layer 18, and an inner layer 22 is provided radially within the intermediate layer 20.

(7) The four layer 16-22 have been coextruded by an extruder 24 as is shown schematically in FIG. 1.

(8) The main component of the outer protection layer 16 is PA6.12. The main component of the barrier layer 18 is PA-MXD6. The main component of the intermediate layer 20 is PA6. The main component of the intermediate layer 22 is PA-MXD6.

(9) Each of the above materials can be provided in grades that are adapted to the respective function, e.g. as a fuel tube for motor vehicle applications.

(10) In general, each of the barrier layer 18 and the inner layer 22 may comprise a partially aromatic polyamide.

(11) The partially aromatic polyamide is preferably PA-MXD6.

(12) The outer protection layer may comprise of materials such as PA6, PA12, PA6.12, PA6.6, PA11, PA6.10 and/or PPA, or may comprise a thermoplastic elastomer.

(13) Similarly, the intermediate layer 20 may comprise at least one of PA6, PA12, PA6.12, PA6.6, PA11, PA6.10, PA10.10 and/or PPA, or may comprise a thermoplastic elastomer.

(14) The inner layer 22 is preferably an electrically conductive layer. The nominal layer thickness of the inner layer 22 is preferably in a range from 0.05 mm to 0.2 mm.

(15) The inner layer 22 and the intermediate layer 20 are preferably directly adjacent to each other. In other words, no separate adhesive layer is provided therebetween.

(16) Preferably, no such adhesive layer is provided between the outer protection layer 16 and the barrier layer 18. However, in some embodiments, a supplemental layer 26 (see FIG. 2) can be provided therebetween.

(17) The multilayer tube 10 has a nominal radial thickness T.sub.10, as shown in FIG. 2.

(18) The outer protection layer 16 has a nominal radial thickness T.sub.16. The barrier layer 18 has a nominal radial thickness T.sub.18. The intermediate layer 20 has a nominal radial thickness T.sub.20, and the inner layer 22 has a nominal radial thickness T.sub.22.

(19) The multilayer tube 10 can be extruded at extrusion speed of approximately 30-40 m/min.

(20) The PA-MXD6 can be provided in a grade that has the following properties:

(21) Tensile property (measured according to ISO527, at 23 C. and at 50% relative humidity:

(22) Tensile modulus: 2.9 to 3.3 GPa

(23) Yield strength: 75 to 81 MPa

(24) Yield elongation: 3% to 5%

(25) Break strength: 52 MPa to 60 MPa

(26) Break elongation: 32% to 40%.

(27) In addition, such grade can have the following flexural properties (measured according to ISAO178 at 23 C. and 50% relative humidity):

(28) Flexural modules: 2.9 to 3.3 GPa

(29) Flexural strength: 115 to 140 MPa.

(30) In addition, such grade may have the following charpy impact strength (measured according to ISO 179/1 eA, 1 eU at 23 C. and 50% relative humidity):

(31) Notched 13.2 to 14.4 kJ/m.sup.2

(32) Unnotched 300 to 350 kJ/m.sup.2.

(33) Finally, the above grade may be provided with the following CE10 barrier property, as a film at 40 C., cup method: 300 hours):

(34) CE10 permeability 0.3 to 0.5 g*mm/(m.sup.2*day)

(35) The PA-MXD6 can be provided in a grade that has a low price, a good adhesiveness to aliphatic PA, a good chemical resistance, a good cold impact strength, a good cold extrudability and a good CE10 barrier property.

(36) In a multilayer tube that uses PA-MXD6 as a barrier layer and for example PA12 as an outer protection layer, no adhesive is needed. The multilayer tube is tolerable to thicker barrier layers. In addition, the barrier layer is tolerable to direct contact with fuel.

(37) The multilayer tube may provide improved pressure and chemical resistance.

(38) Further, in addition to a simpler structure, a mild process may be established, by using mild processing temperatures at low cost, wherein the resource of a barrier layer can be multiplied.

(39) Finally, the barrier property can be enhanced. The multilayer tube can have a lower oligomer, and can have a rigid structure.

(40) It is to be understood that the foregoing description is not a definition of the invention, but is a description of one or more preferred exemplary embodiments of the invention. The invention is not limited to the particular embodiment(s) disclosed herein, but rather is defined solely by the claims below. Furthermore, the statements contained in the foregoing description relate to particular embodiments and are not to be construed as limitations on the scope of the invention or on the definition of terms used in the claims, except where a term or phrase is expressly defined above. Various other embodiments and various changes and modifications to the disclosed embodiment(s) will become apparent to those skilled in the art. All such other embodiments, changes, and modifications are intended to come within the scope of the appended claims.

(41) As used in this specification and claims, the terms for example, e.g., for instance, such as, and like, and the verbs comprising, having, including, and their other verb forms, when used in conjunction with a listing of one or more components or other items, are each to be construed as open-ended, meaning that that the listing is not to be considered as excluding other, additional components or items. Other terms are to be construed using their broadest reasonable meaning unless they are used in a context that requires a different interpretation.