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EP-4741151-A1 - MULTILAYER PIPE FOR AN AIR CONDITIONING SYSTEM OF A MOTOR VEHICLE

EP4741151A1EP 4741151 A1EP4741151 A1EP 4741151A1EP-4741151-A1

Abstract

Pipe (10) for an air conditioning system of a motor vehicle; said pipe comprising: an inner tube (12), located in a radially internal position and configured to carry a fluid to be transported, wherein the inner tube (12) is made of one of the following materials: PA6/66, PA66, PA6T/66, PA6T/6, or EX1; an outer tube (14), located in a radially external position, wherein the outer tube (14) is made of polyamide having, in the repeating units of its macromolecules, a ratio between the number of CH2 methylene groups and the number of CONH amide groups greater than or equal to 8; wherein EX1 is a reactive thermoplastic composition, comprising a continuous phase of at least one thermoplastic polymer, and in which a discontinuous phase is dispersed which is based on at least one reactive reinforcing chemical agent.

Inventors

  • ROSSI, Katia
  • PARENTE, GIUSEPPE
  • HÉRAULT, Florence

Assignees

  • HUTCHINSON S.r.l.

Dates

Publication Date
20260513
Application Date
20251106

Claims (12)

  1. Pipe (10) for an air conditioning system of a motor vehicle; said pipe comprising: - an inner tube (12), located in a radially internal position and configured to carry a fluid to be transported, wherein the inner tube (12) is made of one of the following materials: PA6/66, PA66, PA6T/66, PA6T/6, or EX1, - an outer tube (14), located in a radially external position, wherein the outer tube (14) is made of polyamide having, in the repeating units of its macromolecules, a ratio between the number of CH2 methylene groups and the number of CONH amide groups greater than or equal to 8; wherein EX1 is the following material: a reactive thermoplastic composition, comprising a continuous phase based on at least one thermoplastic polymer, and in which a discontinuous phase is dispersed which is based on at least one reactive reinforcing chemical agent, wherein said reactive reinforcing chemical agent may be immiscible with said at least one thermoplastic polymer, and wherein said reinforcing chemical agent is selected from the group including epoxy resins, polyorganosiloxanes having SiH functional group(s), diisocyanates or polyisocyanates, and mixtures thereof; wherein such thermoplastic composition is free of any compatibilizing agents between the continuous phase and the discontinuous phase, and comprises the product of an in situ grafting, branching and/or crosslinking reaction, wherein such product is obtained by reactive mixing of said continuous and discontinuous phases at a shear rate greater than 10 2 s -1 ; said product of the in situ reaction between said reactive reinforcing agent and the polymeric chains of said at least one thermoplastic polymer is such that the latter has a grafted, branched or crosslinked structure, and that the discontinuous phase is homogeneously dispersed in the continuous phase.
  2. Pipe according to claim 1, wherein the outer tube (14) is made of one of the following materials: PA610, PA612, PA12, PA11, PA1012, or PA10T.
  3. Pipe according to claim 1 or 2, wherein the inner tube (12) is made of PA6/66.
  4. Pipe according to claim 1 or 2, wherein the inner tube (12) is made of EX1.
  5. Pipe according to claim 4, wherein the inner tube (12) is made of the following material called EX2: said EX1 material, wherein said at least one thermoplastic polymer is selected from the group including homopolymers and copolymers of olefins, aliphatic, semi-aromatic and aromatic polyamides of the polyphthalamide type, polyimides (PI), polyamide-imides (PAI), polyetherimides (PEI), thermoplastic elastomers (TPE), polyphenylsulfones, polyethersulfones (PES), polystyrenes (PS), polysulfones (PSU), polyesters, ethylene polyoxides and other olefin-based monomers, polyether ether ketones (PEEK), polyether ketones (PEK), polyetherketoneketone (PEKK), block copolymers of the same, and mixtures thereof.
  6. Pipe according to any one of the preceding claims, comprising at least one intermediate tube (16), radially interposed between the inner tube (12) and the outer tube (14).
  7. Pipe according to claim 6, wherein said intermediate tube (16) is made of EVOH.
  8. Pipe according to any one of the preceding claims, wherein the thickness of the inner tube (12) is greater than the thickness of the outer tube (14).
  9. Pipe according to claim 5, wherein the inner tube (12) is made of the following material called EX3: said EX2 material, wherein said discontinuous phase is based on at least one epoxy resin, and preferably on an amide crosslinking system with or without an acrylated or methacrylated amide block agent; wherein said continuous phase is selected from the group including aliphatic, semi-aromatic and aromatic polyamides of the polyphthalamide type.
  10. Air conditioning system for a motor vehicle, comprising a pipe (10) according to any one of the preceding claims.
  11. Motor vehicle comprising an air conditioning system according to claim 10.
  12. Method for making a pipe (10) according to any one of claims 1 to 9, comprising the steps of simultaneously extruding both the inner tube (12) and the outer tube (14).

Description

Technical field The present invention relates to a multilayer pipe for an air conditioning system of a motor vehicle. The pipe is configured to transport a fluid circulating in the air conditioning system. Technical background In the automotive field, the pipes currently being used for air conditioning systems are made of aluminium, possibly with a rubber tube. This solution can ensure product functionality, but has some drawbacks due to: heavy weight, poor vibration absorption, generally high cost, risk of permanent deformation. Moreover, the connections between the pipe's ends and the fittings must be made by brazing or cold-deformation, which are processes that require much energy. US 2023/055055 A1 discloses a hose for transportation of refrigerant, which includes an inner layer, a reinforcing layer, and an outer layer. The inner and outer layers each include a thermoplastic resin composition having a sea-island structure including a matrix containing a thermoplastic resin and a domain containing an elastomer. The water vapour permeability coefficient of the thermoplastic resin composition of the outer layer, at a temperature of 60 °C and a relative humidity of 100%, is 10.0 g·mm/(m2·24 h) or less. The oxygen permeability coefficient of the thermoplastic resin composition of the inner layer, at a temperature of 21 °C and a relative humidity of 50%, is 0.05 cm3·mm/(m2·day·mmHg) or less. The water vapour permeation amount of the hose is 6.0 mg/(240 h·cm2) or less. The hydrofluoroolefin HFO-1234yf permeation amount of the hose is 170 g/(m2·72 h) or less, and the mass per 1 m2 of the outer surface area of the hose if 3,000 g/m2 or less. Summary of the invention It is one object of the present invention to provide a pipe able to overcome the drawbacks of the prior art. According to the present invention, this object is achieved through a pipe having the technical features set out in the appended independent claim. In particular, such technical features result in a pipe with improved mechanical strength, which will maintain its insulating properties even after having been bent. Another advantage lies in the fact that the pipe can be manufactured easily, quickly and economically, while ensuring good thermal insulation. It is understood that the appended claims are an integral part of the technical teachings provided in the following detailed description of the present invention. In particular, the appended dependent claims define some preferred embodiments of the present invention that include some optional technical features. Further features and advantages of the present invention will become apparent in light of the following detailed description, provided herein merely as a non-limiting example and referring, in particular, to the annexed drawings as summarized below. Brief description of the drawings Figure 1 is a perspective view of a pipe made in accordance with an exemplary embodiment of the present invention.Figure 2 is a perspective view of a pipe made in accordance with another exemplary embodiment of the present invention. Detailed description of the invention With reference to the drawings, numeral 10 designates as a whole a pipe for an air conditioning system of a motor vehicle; said pipe 10 comprising: an inner tube 12, located in a radially internal position and configured to carry a fluid to be transported, wherein inner tube 12 is based on, in particular made of, one of the following materials: PA6/66, PA66, PA6T/66, PA6T/6, or "EX1" (which will be defined later on),an outer tube 14, located in a radially external position, wherein outer tube 14 is based on, in particular made of, polyamide having, in the repeating units of its macromolecules, a ratio between the number of CH2 methylene groups and the number of CONH amide groups greater than or equal to 8. For example, pipe 10 can be used in a motor vehicle, like a car. In particular, pipe 10 may find application in an air conditioning system of a motor vehicle, particularly for high-pressure liquid lines. Inner tube 12 is configured to carry a fluid to be transported, in particular a refrigerant fluid, such as refrigerant liquid or refrigerant gas. The coolant fluids that can flow in inner tube 12 may be per se known. Inner tube 12 has low permeability to gases (e.g. R-1234YF, R134a, R290, or R744) used in air conditioning circuits, thus limiting the dispersion thereof in the outside environment. PA6/66, PA66, PA6T/66, or PA6T/6, which are the materials that inner tube 12 is made of, are particular types of polyamide. Preferably, inner tube 12 is based on, in particular made of, PA6/66. This material offers a particularly satisfactory level of impermeability to gases used in air conditioning circuits. According to some preferred variants of the invention, inner tube 12 is based on, in particular made of, the material defined by any one of claims 11-16 of patent EP 2415824 B1, or the material defined by any one of claims 13-24 of patent FR 29