MULTILAYER TUBE FOR AUTOMOTIVE APPLICATIONS

Abstract

A multilayer tube is provided for use in with transmission oil or heating and cooling fluid applications in motor vehicles. The multilayer tube has an outer layer comprising an aliphatic or an aromatic polyamide to provide protection from the outside environment; a middle layer of a lower cost material that comprises from 20-90% of the thickness of the tube materials; and an inner layer that has excellent resistance to transmission oil or glycol coolant and temperature.

Claims

1. A multilayer tube comprising an outer layer comprising an aliphatic or an aromatic polyamide; a middle layer of aliphatic polyamide comprising from 20-90% of a combined thickness of three layers within said multilayer tube; and an inner layer comprising an aliphatic or aromatic polyamide.

2. The multilayer tube of claim 1 wherein said middle layer comprises about 20-90% of said combined thickness.

3. The multilayer tube of claim 1 wherein said middle layer comprises about 30-80% of said combined thickness.

4. The multilayer tube of claim 1 wherein said middle layer is further comprising about 1-49 wt % elastomer.

5. The multilayer tube of claim 1 in a transmission cooling system at temperatures from about −40 C to 150 C.

6. The multilayer tube of claim 1 in an automotive heating and cooling system from about −40 C to 130 C.

7. The multilayer tube of claim 1 having a smooth bore or a corrugated surface.

8. The multilayer tube of claim 1 wherein the outer layer is a polyamide polymer selected from PA610, PA612, PA1010, PA1012, PA9T, PPA and Nylon MXD6.

9. The multilayer tube of claim 1 wherein the outer layer is a polyamide polymer selected from PA610, PA612, PA1010, and PA1012.

10. The multilayer tube of claim 1 wherein the middle layer is a polyamide polymer selected from PA6 and PA66.

11. The multilayer tube of claim 1 wherein the middle layer is a polyamide polymer selected from PA6, PA610 and PA612.

12. The multilayer tube of claim 1 wherein the inner layer is a polyamide polymer selected from PA610, PA612, PA1010, PA1012, PA9T, PPA and Nylon MXD6.

13. The multilayer tube of claim 1 wherein said inner layer is PA610 and said middle layer comprises PA6.

14. The multilayer tube of claim 1 wherein a layer of adhesive is located between said inner layer and said middle layer.

15. The multilayer tube of claim 1 wherein a layer of adhesive is located between said middle layer and said outer layer.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0014] Exemplary embodiments of the disclosure are explained in more detail in the following description and are represented in the drawings, in which:

[0015] FIG. 1 shows a schematic cross section of a multilayer tube with three layers.

[0016] FIG. 2 shows a schematic cross section of a multilayer tube with five layers having a layer of adhesive between the outer and middle layer, and having a layer of adhesive between the middle and inner layer

[0017] FIG. 3 shows a schematic cross section of a multilayer tube with four layers having a layer of adhesive between the outer and middle layer.

[0018] FIG. 4 shows a schematic cross section of a multilayer tube with four layers having a layer of adhesive between the middle and inner layer.

DETAILED DESCRIPTION

[0019] The disclosure provides a multilayer tube for conveying transmission oil or for conveying vehicle heating or cooling fluids, comprising an outer layer, an intermediate layer radially within the outer layer comprising an aliphatic polyamide, and an inner layer radially within the intermediate layer, wherein the layers are co-extruded layers.

[0020] Further, the multilayer tube is made by a method of manufacturing a multi-layer tube comprising the steps of providing an extrudable outer protection layer material for an outer protection layer, 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 an aliphatic or an aromatic polyamide, and co-extruding at least two of the layers.

[0021] The middle layer is selected as a lower cost material in order to provide a significant cost saving in products yet retain the desired overall properties and performance.

[0022] The multilayer tube for transmission oil applications contains an aromatic or aliphatic polyamide used for the outer layer that can be any material selected from the group of PA610, PA612, PA1010, PA1012 PA9T, PPA or Nylon MXD6. The middle layer often contains an elastomer such as from about 1% to 49% elastomer by weight. The inner layer is selected to be a similar material as the outer layer such as PA610, PA612, PA1010, PA1012 PA9T, PPA or Nylon MXD6.

[0023] PA610 is a polyamide made from one monomer with six carbon atoms and the other monomer having ten carbon atoms which is made from hexamethylenediamine and sebacic acid. Similarly, PA612 is a copolymer of a linear 6C diamine and a 12C diacid. PA1010 is the polycondensation product of 1,10-decamethylene diamine and 1,10-decanedioic acid (sebacic). PA1012 is a biobased polyamide.

[0024] In another preferred embodiment, the intermediate layer comprises at least one of PA6, PA66, PA610, PA612, PA12 or PA11.

[0025] Due to the general ability to adhere between the outer protection layer and the barrier layer, an adhesive layer may be necessary between outer and middle layers or between inner and middle layers.

[0026] The aromatic or partially aromatic polyamide used for the outer layer of the multilayer tube for heating and cooling fluids can be any material selected from the group of PA610, PA612, PA1010, PA1012 PA9T, PPA or Nylon MXD6. The intermediate or middle layer is an aliphatic polyamide. The middle layer often contains an elastomer such as from about 1% to 49% elastomer by weight. The middle layer may be selected from PA6, PA612 or PA610, PA12 or PA11. The inner layer is selected to be a similar material as the outer layer such as PA610, PA612, PA1010, PA1012 PA9T, PPA or Nylon MXD6

[0027] The middle layer is selected to provide sufficient of the desired properties but especially at lower cost compared to the inner and outer layer materials that are more critical in being the surface that the fluid is conveyed through in the case of the inner layer or the layer that is exposed to the environment in the case of the outer layer. In addition, depending upon the materials selected for the layers, there may be a layer of adhesive between the outer layer and the middle layer and/or the middle layer and the inner layer.

[0028] It will be understood that the features of the disclosure mentioned above and those yet to be explained below can be used not only in the respective combination indicated, but also in other combinations or in isolation, without leaving the scope of the present invention.

EMBODIMENTS

[0029] A multilayer tube according to the disclosure is generally shown in FIG. 1 and given the reference numeral 10.

[0030] The multilayer tube 10 is provided in FIG. 1. There are three layers shown, an outer layer 16, a middle or intermediate layer 20 and an inner layer 22. The most effective manufacturing method for layers 16, 20 and 22 is coextrusion. The middle layer may be 20-90% of the thickness of the tube in some embodiments, 30-80% of the thickness in other embodiments.

[0031] Each of the above materials can be provided in grades that are adapted to the respective function.

[0032] The outer layer may comprise of materials such as PA610, PA612, PA1010 or PA1012, PA9T. The intermediate layer 20 may comprise at least one of PA6, PA66, PA610, PA612, PA12 or PA11. The inner layer 22 may comprise at least one of PA610, PA612, PA1010, PA1012, PA9T, PPA or Nylon MXD6. The intermediate layer is a material that costs less than the outer layer or the inner layer and is a material that adheres to those layers so that an adhesive is not necessary in the embodiment shown in FIG. 1.

[0033] A second embodiment is shown in FIG. 2 in which layers of adhesive are shown between the outer layer and intermediate layer as well as between the inner layer and the intermediate layer. The adhesive may be a polyamide or other known adhesive to adhere to the polyamides in the three main layers. In FIG. 2 is shown a tube 30 in cross section with an outer layer 40, then a layer of adhesive 42, an intermediate layer 44, an adhesive layer 46 and an inner layer 48. The middle layer may be 20-90% of the thickness of the tube in some embodiments, 30-80% of the thickness in other embodiments. Each of the above materials can be provided in grades that are adapted to the respective function. The outer layer 40 may comprise materials such as PA610, PA612, PA1010, PA1012, PA9T, PPA or Nylon MXD6. The intermediate layer 44 may comprise at least one of PA6, PA66, PA610, PA612, PA12 or PA11. The inner layer 48 may comprise at least one of PA610, PA612, PA1010, PA1012, PA9T, PPA or Nylon MXD6.

[0034] A third embodiment is shown in FIG. 3 which is identical to FIG. 2 except for the absence of adhesive layer 46. FIG. 4 shows a fourth embodiment that is identical to FIG. 2 except for the absence of adhesive layer 42.