Low-temperature-resistant flame-retardant multi-barrier multi-layer composite fuel pipe and preparation method and application thereof

Abstract

The present application relates to the technical field of pipe fittings, in particular to a low-temperature-resistant flame-retardant multi-barrier multilayer composite fuel pipe and a preparation method and application thereof. The present application provides a low-temperature-resistant flame-retardant multi-barrier multilayer composite fuel pipe, which comprises, from outside to inside, a low-temperature-resistant flame-retardant layer, a barrier adhesive layer and a first barrier layer which are stacked in sequence; the material of the low-temperature-resistant flame-retardant layer comprises polyamide-11 or polyamide-12. The low-temperature-resistant flame-retardant multi-barrier multilayer composite fuel pipe provided by the present application has the advantages of high low-temperature resistance, high flame retardancy, high impact resistance, high corrosion resistance, high permeation resistance and high high-low temperature alternating capacity, and no oligomer and additive is precipitated.

Description

Technical Field

[0001] This invention relates to the field of pipe fittings technology, specifically to a low-temperature resistant, flame-retardant, multi-barrier, multi-layer composite fuel pipe, its preparation method, and its application. Background Technology

[0002] Currently, most fuel lines used in passenger vehicles are single-layer or multi-layer polymer pipes. While they possess basic oil resistance and flexibility, they also have significant limitations. On the one hand, ordinary nylon materials have weak flame retardant properties. Once exposed to external fire sources in high-temperature areas such as engine compartments, they are prone to melting and burning, which can exacerbate the spread of fire and make it difficult to meet increasingly stringent vehicle fire safety standards. Even if a barrier material is added to the outer layer of the nylon tube, the composite structure may cause delamination or peeling under external force or thermal cycling, resulting in the failure of the flame retardant layer and increasing the cost of the tube. On the other hand, traditional tubes have limited efficiency in blocking hydrocarbons. Under high-temperature and high-pressure conditions such as turbocharging and high-pressure injection, the fuel penetration rate is high, which not only causes excessive emissions but also poses a risk of volatile organic compounds (VOCs) escaping. Although multi-layer tubes introduce EVOH barrier layers, the processing window of EVOH is narrow, and it is prone to degradation due to temperature fluctuations when co-extruded with other materials, resulting in a decrease in barrier performance. In addition, under alternating high and low temperature conditions (seasonal changes or long-term engine operation), the tube is prone to aging and becoming brittle, with insufficient low-temperature impact resistance. It is easily deformed or even cracked when impacted by external forces such as stones, thus limiting its overall service life. Summary of the Invention

[0003] Therefore, the purpose of this invention is to provide a low-temperature resistant, flame-retardant, multi-barrier, multi-layer composite fuel pipe, its preparation method, and its application. The low-temperature resistant, flame-retardant, multi-barrier, multi-layer composite fuel pipe provided by this invention exhibits strong low-temperature resistance, strong flame retardancy, strong impact resistance, strong corrosion resistance, strong permeability resistance, and strong resistance to high and low temperature alternation, and does not show any oligomer or additive precipitation.

[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution: The present invention also provides a low-temperature resistant flame-retardant multi-barrier multilayer composite fuel pipe, which includes, from the outside to the inside, a low-temperature resistant flame-retardant layer, a barrier adhesive layer and a first barrier layer stacked sequentially. The material of the low-temperature resistant flame-retardant layer includes polyamide-11 or polyamide-12.

[0005] Preferably, the material of the barrier adhesive layer includes poly(m-phenylene sebacate).

[0006] Preferably, the material of the first barrier layer includes a non-conductive material or a conductive material. The non-conductive material includes one of polyvinylidene fluoride, ethylene-tetrafluoroethylene polymer, PA9T, PA10T, poly(m-phenylene adipamide), and ethylene-fluorinated ethylene propylene copolymer. The conductive material includes one of conductive polyvinylidene fluoride material, conductive ethylene-tetrafluoroethylene polymer, PA9Tcond, PA10Tcond, conductive poly(m-phenylene adipamide), and conductive ethylene-fluorinated ethylene propylene copolymer.

[0007] Preferably, an outer adhesive layer and a second barrier layer are further included between the low-temperature flame-retardant layer and the barrier adhesive layer, and the outer adhesive layer is in contact with the low-temperature flame-retardant layer.

[0008] Preferably, the material of the outer adhesive layer includes an adhesive resin.

[0009] Preferably, the material of the second barrier layer includes one of polyvinylidene fluoride, ethylene-vinyl alcohol copolymer, ethylene-tetrafluoroethylene polymer, PA9T, PA10T, poly(m-phenylene adipamide), and ethylene-fluorinated ethylene propylene copolymer.

[0010] Preferably, the thickness of the low-temperature resistant flame-retardant layer is (0.45±0.1) mm or (0.7±0.1) mm; The thickness of the outer adhesive layer is (0.1±0.03) mm; The thickness of the second barrier layer is (0.15±0.03) mm; The thickness of the barrier adhesive layer is (0.1±0.03) mm; The thickness of the first barrier layer is (0.2±0.05) mm.

[0011] The present invention also provides a method for preparing the low-temperature flame-retardant multi-barrier composite fuel pipe described in the above technical solution, comprising the following steps: co-extruding the raw materials of the low-temperature flame-retardant layer, the raw materials of the barrier adhesive layer and the raw materials of the first barrier layer to obtain the low-temperature flame-retardant multi-barrier composite fuel pipe.

[0012] Preferably, when the low-temperature flame-retardant layer and the barrier adhesive layer are further divided into an outer adhesive layer and a second barrier layer, the co-extrusion is: co-extruding the raw materials of the low-temperature flame-retardant layer, the outer adhesive layer, the second barrier layer, the barrier adhesive layer, and the first barrier layer.

[0013] The present invention also provides the application of the low-temperature resistant, flame-retardant, multi-barrier, multi-layer composite fuel pipe described in the above technical solution or the low-temperature resistant, flame-retardant, multi-barrier, multi-layer composite fuel pipe prepared by the preparation method described in the above technical solution in vehicle fuel lines.

[0014] The outermost material of the low-temperature resistant, flame-retardant, multi-barrier, multi-layer composite fuel pipe provided by this invention is modified polyamide-11 or polyamide-12. In addition to possessing the excellent physical, thermal, and electrical properties of other PA11 / PA12, it also has low-temperature resistance of -60℃ and excellent flame retardancy. It can be used in extreme low-temperature environments or high-temperature environments around the engine to improve the safety of the entire vehicle. There are no interface defects between the layers, and the flame-retardant components are uniformly dispersed throughout the pipe wall, which can better cooperate to withstand thermal aging, vibration, and pressure fluctuations, resulting in higher long-term reliability. It is suitable for large-scale applications in the automotive industry. Through formulation design, thinner and lighter pipe walls can be achieved while meeting performance requirements, thus contributing to fuel economy. It can also be used as a fuel vapor pipeline.

[0015] Furthermore, the low-temperature resistant, flame-retardant, multi-barrier, multi-layer composite fuel pipe provided by this invention uses poly(m-phenylene sebacate) (MXD10), which has adhesive properties, as the intermediate layer material (barrier adhesive layer). This barrier adhesive layer can directly bond the outermost low-temperature resistant flame-retardant layer and the innermost first barrier layer without the need for an additional resin adhesive layer. The outer layer material of this barrier adhesive layer is polyamide-11 or polyamide-12, and the inner layer material is PVDF / ETFE / PA9T / PA10T / MXD6 or its conductive material, thus achieving both double barrier properties and economic efficiency.

[0016] Furthermore, poly(m-phenylene sebacate) (MXD10) can also be used as the fourth layer material (barrier adhesive layer) in a five-layer pipe structure. The outer layer material of this barrier adhesive layer, the second barrier layer material, is EVOH / PVDF / ETFE / PA9T / PA10T / MXD6, and the inner layer material is PVDF / ETFE / PA9T / PA10T / MXD6 or its conductive material. The use of multiple barrier layers can effectively prevent fuel from penetrating to the outside of the pipe, meeting the national standard (China VI) requirements or even higher requirements; it can also effectively prevent small molecule additives and oligomers in the outer layer material from entering the inside of the pipe and forming precipitates that block the pipeline.

[0017] This invention, through the rational combination of materials in each layer and the one-time molding process using multi-layer co-extrusion, not only saves costs but also achieves environmental protection and energy conservation, possessing significant application potential. The low-temperature resistant, flame-retardant, multi-barrier, multi-layer composite fuel pipe provided by this invention, when used as a vehicle fuel pipeline, can enhance and improve the overall performance of the vehicle. Besides its use as a vehicle fuel vapor pipeline, it can also be used as a pipeline for transporting other liquids. Attached Figure Description

[0018] Figure 1 A schematic diagram of a low-temperature resistant, flame-retardant, multi-barrier, multi-layer composite fuel pipe with a three-layer structure. Figure 2This is a schematic diagram of a low-temperature resistant, flame-retardant, multi-barrier, multi-layer composite fuel pipe with a five-layer structure. Detailed Implementation

[0019] This invention provides a low-temperature resistant, flame-retardant, multi-layered composite fuel pipe with multiple barriers, comprising, from the outside to the inside, a low-temperature resistant flame-retardant layer, a barrier adhesive layer, and a first barrier layer stacked sequentially. This low-temperature resistant, flame-retardant, multi-layered composite fuel pipe has a three-layer structure, as shown in the schematic diagram. Figure 1 .

[0020] Unless otherwise specified, the materials and equipment used in this invention are all commercially available products in the field.

[0021] In this invention, an outer adhesive layer and a second barrier layer may be included between the low-temperature flame-retardant layer and the barrier adhesive layer, with the outer adhesive layer in contact with the low-temperature flame-retardant layer. This low-temperature flame-retardant multi-barrier multilayer composite fuel pipe has a five-layer structure, as shown in the schematic diagram. Figure 2 .

[0022] In this invention, the material of the low-temperature (-60℃) flame-retardant layer may include polyamide-11 or polyamide-12. In this invention, the thickness of the low-temperature flame-retardant layer in a three-layer structured, multi-layer composite fuel pipe with multiple barriers can be (0.7±0.1) mm, (0.7±0.05) mm, or further (0.7±0.02) mm, specifically 0.7 mm; the thickness of the low-temperature flame-retardant layer in a five-layer structured, multi-layer composite fuel pipe with multiple barriers can be (0.45±0.1) mm, (0.45±0.05) mm, or further (0.45±0.02) mm, specifically 0.45 mm.

[0023] In this invention, the material of the barrier adhesive layer may include poly(m-phenylene sebacate). In this invention, the thickness of the barrier adhesive layer may be (0.1±0.03) mm, (0.1±0.02) mm, (0.1±0.01) mm, or specifically 0.1 mm.

[0024] In this invention, the material of the first barrier layer includes a non-conductive material or a conductive material; the non-conductive material may include one of polyvinylidene fluoride (PVDF), ethylene-tetrafluoroethylene polymer (PVDF), PA9T, PA10T, poly(m-phenylene adipamide) (MXD6), and ethylene-fluorinated ethylene propylene copolymer (ETEP); the conductive material includes one of conductive polyvinylidene fluoride material (PVDFcond), conductive ethylene-tetrafluoroethylene polymer (ETFEcond), PA9Tcond, PA10Tcond, conductive poly(m-phenylene adipamide) (MXD6cond), and conductive ethylene-fluorinated ethylene propylene copolymer (ETEPcond). In this invention, the thickness of the first barrier layer may be (0.2±0.05) mm, (0.2±0.03) mm, or further (0.2±0.01) mm.

[0025] In this invention, an outer adhesive layer and a second barrier layer may be included between the low-temperature flame-retardant layer and the barrier adhesive layer, with the outer adhesive layer in contact with the low-temperature flame-retardant layer. This low-temperature flame-retardant multi-barrier multilayer composite fuel pipe has a five-layer structure, as shown in the schematic diagram. Figure 2 .

[0026] In this invention, the material of the outer adhesive layer may include an adhesive resin. This invention does not have a specific limitation on the adhesive resin; any adhesive resin well-known to those skilled in the art can be used. In this invention, the thickness of the outer adhesive layer can be (0.1±0.03) mm, (0.1±0.02) mm, or further (0.1±0.01) mm, specifically 0.1 mm.

[0027] In this invention, the material of the second barrier layer may include one of polyvinylidene fluoride (PVDF), ethylene-vinyl alcohol copolymer (EVOH), ethylene-tetrafluoroethylene polymer (ETFE), PA9T, PA10T, poly(m-phenylene adipamide) (MXD6), and ethylene-fluorinated ethylene propylene copolymer (ETEP). In this invention, the thickness of the second barrier layer may be (0.15±0.03) mm, (0.15±0.02) mm, or further (0.15±0.01) mm, specifically 0.15 mm.

[0028] The present invention also provides a method for preparing the low-temperature flame-retardant multi-barrier composite fuel pipe described in the above technical solution, comprising the following steps: co-extruding the raw materials of the low-temperature flame-retardant layer, the raw materials of the barrier adhesive layer and the raw materials of the first barrier layer (three-layer structure) to obtain the low-temperature flame-retardant multi-barrier composite fuel pipe.

[0029] In this invention, when an outer adhesive layer and a second barrier layer are further included between the low-temperature flame-retardant layer and the barrier adhesive layer, the co-extrusion (five-layer structure) is as follows: the raw materials of the low-temperature flame-retardant layer, the raw materials of the outer adhesive layer, the raw materials of the second barrier layer, the raw materials of the barrier adhesive layer and the raw materials of the first barrier layer are co-extruded in multiple layers.

[0030] This invention uses a co-extrusion method to prepare the raw materials of each layer, resulting in no interface defects. The flame-retardant components are uniformly dispersed throughout the pipe wall, which can better withstand thermal aging, vibration, and pressure fluctuations, resulting in higher long-term reliability. The one-step extrusion molding process has high production efficiency, near 100% material utilization, and lower overall cost, making it suitable for large-scale applications in the automotive industry. Through formula design, thinner and lighter pipe walls can be achieved while meeting performance requirements, contributing to fuel economy. It can also be used as a fuel vapor pipeline.

[0031] This invention also provides the application of the low-temperature resistant, flame-retardant, multi-barrier, multi-layer composite fuel pipe described in the above-described technical solutions, or the low-temperature resistant, flame-retardant, multi-barrier, multi-layer composite fuel pipe prepared by the preparation method described in the above-described technical solutions, in vehicle fuel lines. In this invention, the fuel line may include a liquid fuel line or a vapor fuel line.

[0032] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0033] Example 1 The low-temperature flame-retardant multilayer composite fuel pipe with a three-layer structure consists of the following layers from the inside out: the first barrier layer is made of polyvinylidene fluoride with a thickness of (0.2±0.05) mm; the barrier bonding layer is made of poly(m-phenylene sebacate) with a thickness of (0.1±0.03) mm; and the low-temperature flame-retardant layer is made of polyamide-11 with a thickness of (0.7±0.1) mm.

[0034] Preparation method: The raw materials of each layer are co-extruded in multiple layers using a multi-layer extruder.

[0035] Example 2 The low-temperature flame-retardant multilayer composite fuel pipe with a three-layer structure consists of the following layers from the inside out: the first barrier layer is made of ethylene-tetrafluoroethylene polymer with a thickness of (0.2±0.05) mm; the barrier bonding layer is made of poly(m-phenylene sebacate) with a thickness of (0.1±0.03) mm; and the low-temperature flame-retardant layer is made of polyamide-12 with a thickness of (0.7±0.1) mm.

[0036] Preparation method: The raw materials of each layer are co-extruded in multiple layers using a multi-layer extruder.

[0037] Example 3 The five-layer low-temperature flame-retardant multi-barrier composite fuel pipe consists of the following layers from the inside out: the first barrier layer is made of PA9T with a thickness of (0.2±0.03) mm; the barrier bonding layer is made of poly(m-phenylene sebacate) with a thickness of (0.1±0.03) mm; the second barrier layer is made of ethylene-fluorinated ethylene propylene copolymer with a thickness of (0.15±0.03) mm; the outer bonding layer is made of adhesive resin with a thickness of (0.10±0.03) mm; and the low-temperature flame-retardant layer is made of polyamide-11 with a thickness of (0.45±0.1) mm.

[0038] Preparation method: The raw materials of each layer are co-extruded in multiple layers using a multi-layer extruder.

[0039] Example 4 The five-layer low-temperature flame-retardant multi-barrier composite fuel pipe consists of the following layers from the inside out: the first barrier layer is made of conductive ethylene-tetrafluoroethylene polymer with a thickness of (0.2±0.03) mm; the barrier adhesive layer is made of poly(m-phenylene adipamide) with a thickness of (0.1±0.03) mm; the second barrier layer is made of poly(m-phenylene adipamide) with a thickness of (0.15±0.03) mm; the outer adhesive layer is made of adhesive resin with a thickness of (0.10±0.03) mm; and the low-temperature flame-retardant layer is made of polyamide-12 with a thickness of (0.45±0.1) mm.

[0040] Preparation method: The raw materials of each layer are co-extruded in multiple layers using a multi-layer extruder.

[0041] Test Example 1 The performance of the low-temperature resistant, flame-retardant, multi-barrier, multi-layer composite fuel pipes prepared in Examples 1 and 2 was tested.

[0042] Low temperature resistance test method: QC / T 798-2022; Flame retardancy test method: UL94-2023; Impact resistance test method: QC / T 798-2022; Corrosion resistance test method: QC / T 798-2022; Penetration resistance test method: GB18352.6-2016; High and low temperature alternation resistance test method: GB16987-2022; Oligomer precipitation test method: TL52712-2016.

[0043] Test results show that the low-temperature resistant, flame-retardant, multi-barrier, multi-layer composite fuel pipe provided by the present invention has strong low-temperature resistance, strong flame retardancy, strong impact resistance, strong corrosion resistance, strong permeability resistance, and strong resistance to high and low temperature alternation, and there is no oligomer or additive precipitation.

[0044] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A low-temperature resistant, flame-retardant, multi-barrier, multi-layer composite fuel pipe, characterized in that, From the outside to the inside, it includes a low-temperature resistant flame-retardant layer, a barrier adhesive layer, and a first barrier layer stacked sequentially. The material of the low-temperature resistant flame-retardant layer includes polyamide-11 or polyamide-12.

2. The low-temperature resistant, flame-retardant, multi-barrier, multi-layer composite fuel pipe according to claim 1, characterized in that, The material of the barrier adhesive layer includes poly(m-phenylene sebacate).

3. The low-temperature resistant, flame-retardant, multi-barrier, multi-layer composite fuel pipe according to claim 1, characterized in that, The first barrier layer is made of either a non-conductive material or a conductive material. The non-conductive material includes one of polyvinylidene fluoride, ethylene-tetrafluoroethylene polymer, PA9T, PA10T, poly(m-phenylene adipamide), and ethylene-fluorinated ethylene propylene copolymer. The conductive material includes one of conductive polyvinylidene fluoride, conductive ethylene-tetrafluoroethylene polymer, PA9Tcond, PA10Tcond, conductive poly(m-phenylene adipamide), and conductive ethylene-fluorinated ethylene propylene copolymer.

4. The low-temperature resistant, flame-retardant, multi-barrier, multi-layer composite fuel pipe according to claim 1, characterized in that, The low-temperature resistant flame-retardant layer and the barrier adhesive layer are further divided into an outer adhesive layer and a second barrier layer, and the outer adhesive layer is in contact with the low-temperature resistant flame-retardant layer.

5. The low-temperature resistant, flame-retardant, multi-barrier, multi-layer composite fuel pipe according to claim 4, characterized in that, The material of the outer adhesive layer includes adhesive resin.

6. The low-temperature resistant, flame-retardant, multi-barrier, multi-layer composite fuel pipe according to claim 4, characterized in that, The material of the second barrier layer includes one of polyvinylidene fluoride, ethylene-vinyl alcohol copolymer, ethylene-tetrafluoroethylene polymer, PA9T, PA10T, poly(m-phenylene adipamide), and ethylene-fluorinated ethylene propylene copolymer.

7. The low-temperature resistant, flame-retardant, multi-barrier, multi-layer composite fuel pipe according to any one of claims 1 to 6, characterized in that, The thickness of the low-temperature resistant flame-retardant layer is (0.45±0.1) mm or (0.7±0.1) mm; The thickness of the outer adhesive layer is (0.1±0.03) mm; The thickness of the second barrier layer is (0.15±0.03) mm; The thickness of the barrier adhesive layer is (0.1±0.03) mm; The thickness of the first barrier layer is (0.2±0.05) mm.

8. The method for preparing the low-temperature resistant, flame-retardant, multi-barrier, multi-layer composite fuel pipe according to any one of claims 1 to 7, characterized in that, Includes the following steps: The raw materials for the low-temperature flame-retardant layer, the barrier adhesive layer, and the first barrier layer are co-extruded to obtain a low-temperature flame-retardant multi-barrier multilayer composite fuel pipe.

9. The preparation method according to claim 8, characterized in that, When the low-temperature flame-retardant layer and the barrier adhesive layer are further separated by an outer adhesive layer and a second barrier layer, the co-extrusion is: co-extruding the raw materials of the low-temperature flame-retardant layer, the outer adhesive layer, the second barrier layer, the barrier adhesive layer, and the first barrier layer.

10. The application of the low-temperature resistant, flame-retardant, multi-barrier, multi-layer composite fuel pipe according to any one of claims 1 to 7, or the low-temperature resistant, flame-retardant, multi-barrier, multi-layer composite fuel pipe prepared by the preparation method according to any one of claims 8 to 9, in vehicle fuel lines.

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