Flexible composite pipeline and preparation method thereof

Abstract

The invention provides a flexible composite pipeline and a preparation method thereof. The flexible composite pipeline comprises: 1) an inner layer formed by thermoplastic resin or an elastomer; 2) a reinforcing layer formed by winding a fiber band formed by fibers impregnated with an elastomer adhesive on the outer wall of the inner layer at an angle of 45-75 degrees with respect to the center of the pipe, and 3) an outer layer bonded on the surface of the reinforcing layer and formed of a thermoplastic resin or an elastomer; the elastomer adhesive of the reinforcing layer comprises the following components in parts by weight: a) 0-20 parts of polypropylene; b) 50-70 parts by weight of a polyolefin elastomer; c) 0-30 parts by weight of polyethylene; d) 0.5-5 parts by weight of a polar monomer; e) 0.2 to 1.5 parts by weight of an initiator; and f) 0-5 parts by weight of an auxiliary agent. The flexible composite pipeline has enhanced flexibility, coil transportation of the pipeline is achieved, long-distance joint-free rapid laying is achieved, and joint hidden danger and construction difficulty are reduced.

Description

Technical Field

[0001] The present invention relates to the field of large-diameter pipelines, and particularly to a large-diameter flexible conveying pipeline and a preparation method thereof. Background Art

[0002] Flexible composite pipelines are a kind of pipeline system composed of different materials, usually consisting of an internal medium conveying layer, a reinforcing layer and a protective layer. These different layers cooperate with each other to make the pipeline have high strength and durability. Flexible composite pipelines have the advantages of light weight, low thermal conductivity, convenient installation and maintenance, etc. Their flexibility and bendability make them suitable for complex terrains and environments where it is difficult to lay traditional pipelines. Therefore, flexible composite pipelines are widely used in fields such as petroleum, chemical industry, water supply, drainage and gas transmission.

[0003] CN201507728U discloses a continuous fiber-reinforced thermoplastic composite pipeline, belonging to the technical field of double-layer pipes. It has at least three layers of structure, and in each layer, a thermoplastic resin is used as the matrix. With continuous fibers or their fabrics with different contents as the reinforcing materials, the continuous fibers or their fabrics are laid in longitudinal, winding and weaving ways. This composite pipeline can improve and enhance impact resistance, aging resistance and temperature resistance, and has more excellent mechanical properties.

[0004] CN213479408U discloses a high-barrier flexible composite pipe, including an inner lining layer, a reinforcing layer and an outer pipe layer. An anti-gas permeation membrane is arranged between the inner lining layer and the reinforcing layer and / or between the reinforcing layer and the outer pipe layer. The anti-gas permeation membrane is a metal sheet layer with a thickness of not less than 0.04 mm, and the metal sheet layer includes but is not limited to aluminum foil, stainless steel thin sheet, or the anti-gas permeation membrane is a non-metal sheet layer composed of at least one isolation layer made of nylon, PVDF, EVOH or POK plastic and protective layers made of polyethylene respectively located on both sides of the isolation layer. This high-barrier flexible composite pipe has the characteristics of high pressure-bearing structural strength, good coiling flexibility, tight anti-gas permeation and long service life.

[0005] CN211624464U discloses a large-diameter flexible composite pipe, which includes an inner pipe, a warp belt, a reinforcing layer and an outer pipe. The warp belt is arranged on the outer surface of the inner pipe along the axial direction parallel to the inner pipe. The reinforcing layer is wound around the warp belt, and the outer pipe is wrapped around the reinforcing layer. The large-diameter flexible composite pipe adds a warp belt layer between the inner pipe and the reinforcing layer, improving the pressure resistance, tensile resistance, oil resistance, corrosion resistance and long service life of the composite pipe. The composite pipe simplifies the winding method, has no special requirements for the winding angle, and one winding tape can solve the one-layer or multi-layer winding structure in the same direction; any metal and non-metal reinforcing strips and wires can be used for winding, and winding tapes of any width can be used, with a wide range of applications; the inner pipe and the outer pipe are not limited to extruded pipes, and are also applicable to the inner pipe sealing layer and the outer pipe protection layer formed by strip winding; the equipment requirements are simple, the cost is low, and it is easy to implement.

[0006] CN201507728U realizes the fiber reinforcement of polyolefin pipes, which can be coiled and transported at a DN200mm diameter, but it is difficult to coil for larger diameters.

[0007] CN211624464U solves the problem of large-diameter pipe processing, but still cannot be coiled.

[0008] Therefore, there is an urgent need for a large-diameter flexible composite pipe that can be coiled. Summary of the Invention

[0009] Aiming at the problems existing in the prior art, the present invention aims to provide a flexible composite pipe and its preparation method. By optimizing the inner and outer layer materials of pipes with different diameters, the flexibility of the pipe is enhanced, realizing the coiled transportation of the pipe, rapid laying without joints over a long distance, reducing the hidden dangers of joints and the construction difficulty.

[0010] According to the first aspect of the present invention, there is provided a flexible composite pipe, which includes:

[0011] (1) An inner layer, which is formed of a thermoplastic resin or an elastomer,

[0012] (2) A reinforcing layer, which is formed by winding a fiber tape impregnated with an elastomer adhesive on the outer wall of the inner layer at an angle of 45 to 75° with respect to the center of the pipe, and

[0013] (3) An outer layer, which is combined on the surface of the reinforcing layer and is formed of a thermoplastic resin or an elastomer;

[0014] Wherein, the elastomer adhesive of the reinforcing layer includes the following components:

[0015] (a) 0 to 20 parts by weight, preferably 5 to 15 parts by weight of polypropylene;

[0016] (b) 50 to 70 parts by weight, preferably 55 to 70 parts by weight of a polyolefin elastomer;

[0017] (c) 0 to 30 parts by weight, preferably 5 to 30 parts by weight of polyethylene;

[0018] (d) 0.5 to 5 parts by weight of a polar monomer;

[0019] (e) 0.2 to 1.5 parts by weight of an initiator; and

[0020] (f) 0 to 5 parts by weight of an auxiliary agent.

[0021] Preferably, the inner diameter of the flexible composite pipe is 20 mm or more, more preferably 100 mm or more.

[0022] Preferably, the inner diameter of the flexible composite pipe is 800 mm or less.

[0023] The flexible composite pipe of the present invention has particularly good flexibility and a small coiling radius, and is particularly suitable for making a large-sized inner diameter.

[0024] Preferably, the melt index of the polypropylene is 0.5 to 5 g / 10 min, preferably 0.5 to 4.0 g / 10 min (2.16 kg, 230 °C, detected according to ISO1133). Preferably, the polypropylene is homopolypropylene or a propylene copolymer.

[0025] Preferably, the propylene copolymer is at least one selected from random copolymers or block copolymers formed by propylene and other C 2-20 α-olefins, and at least one of terpolymers of propylene, ethylene and at least one other C 2-20 α-olefins, or a mixture of at least two of them. Among them, the weight ratio of the propylene unit in the propylene copolymer is 50% or more.

[0026] Preferably, the melt index of the polyolefin elastomer is 0.1 to 5.0 g / 10 min, preferably 0.2 to 2.0 g / 10 min (2.16 kg, 190 °C, detected according to ISO1133).

[0027] Preferably, the polyolefin elastomer is a copolymer of ethylene and propylene, a copolymer of ethylene and 1-butene, a copolymer of ethylene and 1-hexene or a copolymer of ethylene and 1-octene.

[0028] Preferably, the melt index of the polyethylene is 0.5 to 20 g / 10 min, preferably 1 to 5 g / 10 min (2.16 kg, 190 °C, detected according to ISO1133).

[0029] Preferably, the polyethylene is high-density polyethylene or linear low-density polyethylene.

[0030] Preferably, the polar monomer is at least one of maleic anhydride, glycidyl methacrylate, fumaric acid, diisopropyl maleate, itaconic acid, citraconic acid and its anhydride, vinyl succinic anhydride, acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, methyl methacrylate, or a mixture of at least two of them.

[0031] Preferably, the initiator is at least one of cumene hydroperoxide, benzoyl peroxide, lauroyl peroxide, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, di-tert-butyl peroxide, cumene hydroperoxide, tert-butyl hydroperoxide, tert-butyl perbenzoate, tert-butyl peroxy pivalate, diisopropyl peroxydicarbonate, and dicyclohexyl peroxydicarbonate, or a mixture of at least two of them.

[0032] Preferably, the auxiliary agent is at least one of triallyl isocyanurate; electron donors such as N,N-dimethylformamide; grafting aids such as styrene; antioxidants such as 1010; tackifying resins such as modified phenolic resin TKM-M80; viscosity regulators such as low molecular weight waxes; light aging resistant agents; heat stabilizers; anti-dripping agents; mold release agents; nucleating agents, or a mixture of at least two of them.

[0033] Preferably, the fibers in the reinforcing layer are selected from glass fibers, carbon fibers, aramid fibers, basalt fibers, ultra-high molecular weight polyethylene fibers, and steel wires.

[0034] Preferably, the weight percentage of the fibers in the fiber tape is 40% to 60%.

[0035] Preferably, the fiber tape is formed by the following steps:

[0036] 1) Mix the components of the elastomeric adhesive to prepare elastomeric adhesive particles;

[0037] 2) Impregnate the fibers: Immerse the fibers in the melt of the elastomeric adhesive and extrude and cool to form a fiber tape.

[0038] Preferably, the step of impregnating the fibers is carried out in a continuous fiber impregnating machine, the width of the laid fibers is 100 to 200 mm, and the impregnating temperature is 230 to 270 °C.

[0039] Preferably, the thickness of the fiber tape is 0.05 to 0.5 mm.

[0040] Preferably, the materials of each layer of the flexible composite pipe are selected as follows according to the inner diameter of the pipe:

[0041] 1) When the inner diameter of the flexible composite pipe is 20 mm to less than 160 mm, the materials of the inner layer and the outer layer are independently selected from PE, PP, PET, PA, and PVDF;

[0042] 2) When the inner diameter of the flexible composite pipe is 160 mm to less than 480 mm, the material of the inner layer is selected from TPU, TPE, EPDM, styrene-butadiene rubber, nitrile rubber, silicone rubber, etc., and the material of the outer layer is selected from PE, PP, PET, PA, and PVDF;

[0043] 3) When the inner diameter of the flexible composite pipe is greater than or equal to 480 mm, the materials of the inner layer and the outer layer are independently selected from TPU, TPE, EPDM, styrene-butadiene rubber, nitrile rubber, silicone rubber, etc.

[0044] Preferably, the thickness of the inner layer is 1 to 10 mm; and / or, the winding layer number of the fiber tape is 2 to 10 layers; and / or, the thickness of the outer layer is 1 to 10 mm.

[0045] According to the second aspect of the present invention, a method for preparing the flexible composite pipe of the present invention is provided, which includes the following steps:

[0046] i) Extrude the inner layer using a fiber tape winding extruder;

[0047] ii) Before the inner layer is cooled, wind the preheated fiber tape on the outer wall of the inner layer at an angle of 45 to 75° with the pipe center, and the winding layer number is 2 to 10 layers, so as to form a reinforcing layer;

[0048] iii) Extrude the outer layer, which is sleeved on the surface of the fiber tape, and cool to obtain the flexible composite pipe,

[0049] The fiber tape is formed by the following steps:

[0050] 1) Mix the components of the elastomeric adhesive to prepare elastomeric adhesive particles;

[0051] 2) Impregnate the fiber: Immerse the fiber in the melt of the elastomeric adhesive, and extrude and cool to form a fiber tape.

[0052] Preferably, the step of impregnating the fiber is carried out in a continuous fiber impregnating machine, the width of the fiber laid flat is 100 to 200 mm, and the impregnating temperature of the elastomeric adhesive is 230 to 270 °C.

[0053] Preferably, the thickness of the fiber tape is 0.05 to 0.5 mm.

[0054] Preferably, the weight percentage of the fiber in the fiber tape is 40% to 60%.

[0055] Preferably, in step ii), the prestress during winding the fiber tape is 1 to 50 N.

[0056] Preferably, the following materials are selected for each layer of the flexible composite pipe according to the pipe inner diameter:

[0057] 1) When the inner diameter of the flexible composite pipe is from 20 mm to less than 160 mm, the materials of the inner layer and the outer layer are independently selected from PE, PP, PET, PA, and PVDF respectively;

[0058] 2) When the inner diameter of the flexible composite pipe is from 160 mm to less than 480 mm, the material of the inner layer is selected from TPU, TPE, EPDM, styrene-butadiene rubber, nitrile rubber, silicone rubber, etc., and the material of the outer layer is selected from PE, PP, PET, PA, and PVDF;

[0059] 3) When the inner diameter of the flexible composite pipe is greater than or equal to 480 mm, the materials of the inner layer and the outer layer are independently selected from TPU, TPE, EPDM, styrene-butadiene rubber, nitrile rubber, silicone rubber, etc.

[0060] Preferably, the thickness of the inner layer is 1 - 10 mm.

[0061] Preferably, the winding layer number of the fiber tape is 2 - 10.

[0062] Preferably, the thickness of the outer layer is 1 - 10 mm.

[0063] Beneficial effects

[0064] In the present invention, the fiber tape is combined with the pipe matrix through a specific adhesive to overcome the risk of delamination; different inner and outer layer materials are selected for pipes with different inner diameters, which not only ensures the strength of the pipe but also provides good flexibility, realizes long-distance coiling of the pipe, long-distance jointless rapid laying, reduces joint hidden dangers and construction difficulties. Description of the drawings

[0065] Figure 1 It is a schematic diagram showing the layer structure of the flexible composite pipe according to the present invention.

[0066] Reference signs

[0067] 1 - Inner layer

[0068] 2 - Reinforcement layer

[0069] 3 - Outer layer Specific embodiments

[0070] The present invention will be described in detail below in conjunction with embodiments. The embodiments of the present invention are only used to illustrate the present invention and do not limit the scope of the present invention.

[0071] Measurement of the coiling radius

[0072] Coiling is carried out using the Zhangjiagang Hengruitai Machinery 50 - 110 automatic coiling machine, with a maximum coiling radius of 1800 mm. Record the minimum coiling radius of the pipe under the maximum torque. The coiling radius of the pipes that cannot be coiled is uniformly recorded as >1800.

[0073] Example 1

[0074] 1. Preparation of elastomeric adhesive

[0075] Mix 5 parts by weight of homopolypropylene (PPH, L5E89, melt index 3.5 g / 10 min), 65 parts by weight of elastomer (POE, 8150, melt index 0.5 g / 10 min), 30 parts by weight of linear low density polyethylene (LLDPE, 7042, melt index 2 g / 10 min), 0.5 part by weight of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, 3.5 parts by weight of MAH, 1 part by weight of styrene (grafting aid), and 0.1 part by weight of Irganox1010 thoroughly in a high-speed mixer, and then conduct reactive extrusion granulation through a twin-screw extruder. Among them, the processing temperature of each section of the twin-screw is 180 - 230 °C to prepare the elastomeric adhesive.

[0076] 2. Preparation of fiber tape

[0077] Use a continuous fiber impregnator to impregnate glass fibers. The fibers are laid flat and pass through a sheet die with a width of 155 mm, and are mixed with the melt of the elastomeric adhesive at the die outlet. The melt temperature of the elastomeric adhesive is 250 °C. After extrusion and cooling, a continuous fiber tape is formed and coiled for standby. The thickness of the fiber tape is 0.1 mm, and the weight fraction of glass fiber in the fiber tape is 50%.

[0078] 3. Extrusion of flexible composite pipe

[0079] Use a fiber tape winding extruder to extrude a composite pipe to prepare a flexible composite pipe.

[0080] First, extrude the inner layer 1 of the pipe. The inner layer material is HDPE (6100M), the inner diameter of the pipe is 110 mm, and the thickness is 4 mm. Then, while it is hot, wind the preheated fiber tape outside the inner layer 1. The winding angle forms a 45° angle with the pipe center. The prestress of the fiber tape is 30 N, and the winding layer number is 6 layers to form the reinforcing layer 2. Then, extrude the outer layer 3 of the composite pipe through a pipe extruder. The outer layer material is HDPE (6100M), and the thickness is 2 mm. It is sleeved on the surface of the fiber tape. After extrusion, it is cooled and sized, and then coiled, wound, and packaged. The performance is shown in Table 1.

[0081] Example 2

[0082] 1. Preparation of elastomeric adhesive

[0083] Mix 10 parts by weight of homopolypropylene (PPH, L5E89), 60 parts by weight of elastomer (POE, 8150), 30 parts by weight of linear low density polyethylene (LLDPE, 7042), 0.5 part by weight of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, 3.5 parts by weight of MAH, 1 part by weight of styrene and 0.1 part by weight of Irganox1010 evenly in a high-speed mixer, and then carry out reactive extrusion granulation through a twin-screw extruder. Among them, the processing temperature of each section of the twin-screw is 180-230 °C to prepare an elastomer adhesive.

[0084] 2. Preparation of fiber tape

[0085] Use a continuous fiber impregnator to impregnate glass fibers. The fibers are laid flat and pass through a sheet die with a width of 155 mm, and are mixed with the melt of the elastomer adhesive at the die. The temperature of the adhesive melt is 250 °C. After extrusion and cooling, a continuous tape is formed and coiled for standby. The thickness of the fiber tape is 0.1 mm, and the weight fraction of glass fiber in the fiber tape is 50%.

[0086] 3. Extrusion of flexible composite pipe

[0087] Use a fiber tape winding extruder to extrude composite pipes.

[0088] First, extrude the inner layer 1 of the pipe. The inner layer material is TPE (Shandong Dawn 7002), the inner diameter of the pipe is 360 mm, and the thickness is 6 mm. Then, while it is still hot, wind the pre-heated fiber impregnated tape on the outside of the inner layer 1. The winding angle forms a 60° angle with the center of the pipe. The prestress of the fiber tape is 20 N, and the number of winding layers is 4 layers, thus forming a reinforcing layer 2. Then, extrude the outer layer 3 of the composite pipe through a pipe extruder. The outer layer material is HDPE, and the thickness is 2 mm. Line it on the surface of the fiber tape. After extrusion, it is cooled and sized, and then coiled, wound and packaged. The performance is shown in Table 1.

[0089] Example 3

[0090] 1. Preparation of elastomer adhesive

[0091] Mix 5 parts by weight of homopolypropylene (PPH, L5E89), 60 parts by weight of elastomer (POE, 8150), 35 parts by weight of linear low density polyethylene (LLDPE, 7042), 0.5 part by weight of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, 3.5 parts by weight of MAH, 1 part by weight of styrene and 0.1 part by weight of Irganox1010 evenly in a high-speed mixer, and then carry out reactive extrusion granulation through a twin-screw extruder. Among them, the processing temperature of each section of the twin-screw is 180-230 °C to prepare an elastomer adhesive.

[0092] 2. Preparation of fiber tape

[0093] The glass fiber is impregnated using a continuous fiber impregnating machine. The fibers are laid flat and pass through a sheet die with a width of 155 mm, and are mixed with the elastomeric adhesive melt at the die exit. The temperature of the elastomeric adhesive melt is 250 °C. After extrusion and cooling, a continuous strip is formed and coiled for standby. The thickness of the fiber strip is 0.1 mm, and the weight fraction of the glass fiber in the fiber strip is 50%.

[0094] 3. Extrusion of flexible composite pipes

[0095] A fiber tape winding extruder is used for the extrusion of composite pipes. First, the inner layer 1 of the pipe is extruded. The inner layer material is TPE, the inner diameter of the pipe is 600 mm, and the thickness is 6 mm. While it is still hot, a pre-heated fiber impregnated tape is wound around the outer wall of the inner layer 1. The winding angle forms an angle of 72° with the pipe center. The prestress of the fiber tape is 40 N, and the number of winding layers is 2 layers, thereby forming the reinforcement layer 2. Then, the outer layer 3 of the composite pipe is extruded through a pipe extruder. The outer layer material is TPE, and the thickness is 4 mm. It is sleeved on the surface of the fiber tape. After extrusion, it is cooled and sized, and then coiled, wound, and packaged.

[0096] Table 1: Materials and properties of flexible composite pipes prepared in Examples 1 to 3

[0097]

[0098] Comparative Example 1

[0099] A fiber tape winding extruder is used for the extrusion of composite pipes.

[0100] First, the inner layer of the pipe is extruded. The inner layer material is HDPE (6100M), the inner diameter of the pipe is 360 mm, and the thickness is 6 mm. Then, while it is still hot, a commercially available pre-heated fiber impregnated tape (Qingdao CIMC Chuangying Composite Materials Technology Co., Ltd., which is a glass fiber impregnated tape with a thickness of 0.1 mm and a glass fiber weight percentage of 50%) is wound around the outside of the inner layer. The winding angle forms an angle of 60° with the pipe center. The prestress of the fiber tape is 20 N, and the number of winding layers is 4 layers. Then, the outer layer of the composite pipe is extruded through a pipe extruder. The outer layer material is HDPE, and the thickness is 2 mm. It is sleeved on the surface of the fiber tape. After extrusion, it is cooled and sized, and then coiled, wound, and packaged. The performance is shown in Table 2.

[0101] Comparative Example 2

[0102] A fiber tape winding extruder is used for the extrusion of composite pipes.

[0103] First, extrude the inner layer of the pipe. The inner layer material is HDPE (6100M), the inner diameter of the pipe is 600 mm, and the thickness is 6 mm. Then, while it is still hot, wind a pre-heated commercially available fiber impregnated tape (Qingdao CIMC Chuangying Composite Materials Technology Co., Ltd., which is a glass fiber impregnated tape with a thickness of 0.1 mm and a glass fiber weight percentage of 50%) around the outside of the inner layer. The winding angle forms a 72° angle with the center of the pipe, the prestress of the fiber tape is 20 N, and the number of winding layers is 2. Then, extrude the outer layer of the composite pipe through a pipe extruder. The outer layer material is HDPE with a thickness of 4 mm. It is lined on the surface of the fiber tape. After extrusion, it is cooled and sized, and then coiled, wound, and packaged. The performance is shown in Table 2.

[0104] Comparative Example 3

[0105] 1. Preparation of fiber tape

[0106] Use a continuous fiber impregnating machine to impregnate glass fibers. The fibers are laid flat and pass through a sheet die with a width of 155 mm, and are mixed with the melt of a commercially available adhesive (Lushan EP252) at the die exit. The melt temperature of the elastomeric adhesive is 250°C. After extrusion and cooling, a continuous fiber tape is formed and coiled for standby. The thickness of the fiber tape is 0.1 mm, and the glass fiber weight percentage is 50%.

[0107] 2. Extrusion of flexible composite pipe

[0108] Use a fiber tape winding extruder to extrude a composite pipe to prepare a flexible composite pipe.

[0109] First, extrude the inner layer of the pipe. The inner layer material is HDPE (6100M), the inner diameter of the pipe is 110 mm, and the thickness is 4 mm. Then, while it is still hot, wind a pre-heated fiber tape around the outside of the inner layer. The winding angle forms a 45° angle with the center of the pipe, the prestress of the fiber tape is 10 N, and the number of winding layers is 6. Then, extrude the outer layer of the composite pipe through a pipe extruder. The outer layer material is HDPE with a thickness of 2 mm. It is lined on the surface of the fiber tape. After extrusion, it is cooled and sized, and then coiled, wound, and packaged. The performance is shown in Table 2.

[0110] Table 2: Materials and properties of the pipes prepared in Comparative Example 1 to Comparative Example 3

[0111]

[0112] It can be seen that the flexible composite pipes of Comparative Example 1 and Comparative Example 2 have a large inner diameter. The inner and outer layer materials are both common HDPE materials on the market, and the coiling radius is very large, which is not conducive to coiling and transportation.

[0113] Comparative Example 3 uses a commercially available adhesive, and the coiling radius is relatively large under the same conditions.

Claims

1. A flexible composite pipe, which comprises: (1) An inner layer formed of a thermoplastic resin or an elastomer, (2) A reinforcing layer formed by winding a fiber tape impregnated with an elastomeric adhesive around the outer wall of the inner layer at an angle of 45 to 75° with respect to the pipe center, and (3) An outer layer bonded to the surface of the reinforcing layer and formed of a thermoplastic resin or an elastomer; Wherein, the elastomeric adhesive of the reinforcing layer comprises the following components: (a) 0 to 20 parts by weight, preferably 5 to 15 parts by weight of polypropylene; (b) 50 to 70 parts by weight, preferably 55 to 70 parts by weight of a polyolefin elastomer; (c) 0 to 30 parts by weight, preferably 5 to 30 parts by weight of polyethylene; (d) 0.5 to 5 parts by weight of a polar monomer; (e) 0.2 to 1.5 parts by weight of an initiator; and (f) 0 to 5 parts by weight of an auxiliary agent.

2. The flexible composite pipe according to claim 1, wherein, the melt index of the polypropylene is 0.5 to 5 g / 10 min, preferably 0.5 to 4.0 g / 10 min, wherein the melt index is measured at 230 °C under a load of 2.16 kg according to ISO1133; and / or the melt index of the polyolefin elastomer is 0.1 to 5.0 g / 10 min, preferably 0.2 to 2.0 g / 10 min, wherein the melt index is measured at 190 °C under a load of 2.16 kg according to ISO1133; and / or the melt index of the polyethylene is 0.5 to 20 g / 10 min, preferably 1 to 5 g / 10 min, wherein the melt index is measured at 190 °C under a load of 2.16 kg according to ISO1133.

3. The flexible composite pipe according to claim 1 or 2, wherein, the polypropylene is a homopolypropylene or a propylene copolymer; and / or the polyolefin elastomer is a copolymer of ethylene and propylene, a copolymer of ethylene and 1-butene, a copolymer of ethylene and 1-hexene or a copolymer of ethylene and 1-octene; and / or the polyethylene is a high-density polyethylene or a linear low-density polyethylene; and / or the polar monomer is at least one of maleic anhydride, glycidyl methacrylate, fumaric acid, diisopropyl maleate, itaconic acid, citraconic acid and its anhydride, vinyl succinic anhydride, acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, methyl methacrylate, or a mixture of at least two of them; and / or the initiator is at least one of cumene hydroperoxide, benzoyl peroxide, lauroyl peroxide, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, di-tert-butyl peroxide, cumene hydroperoxide, tert-butyl hydroperoxide, tert-butyl peroxybenzoate, tert-butyl peroxypivalate, diisopropyl peroxydicarbonate and dicyclohexyl peroxydicarbonate, or a mixture of at least two of them; and / or The auxiliary agent is triallyl isocyanurate; electron donors such as N,N-dimethylformamide; grafting aids such as styrene; antioxidants such as 1010; tackifying resins such as modified phenolic resin TKM-M80; viscosity regulators such as low molecular weight waxes; light anti-aging agents; heat stabilizers; anti-dripping agents; release agents; nucleating agents, at least one of them, or a mixture of at least two of them.

4. The flexible composite pipe according to claim 3, wherein, The propylene copolymer is at least one selected from random copolymers or block copolymers formed by propylene and other C 2-20 α-olefins, and at least one of propylene-ethylene-α-olefin terpolymers with at least one other C 2-20 α-olefin, or a mixture of at least two of them.

5. The flexible composite pipe according to any one of claims 1 to 4, wherein, The materials of each layer of the flexible composite pipe are selected as follows according to the inner diameter of the pipe: 1) When the inner diameter of the flexible composite pipe is 20 mm to less than 160 mm, the materials of the inner layer and the outer layer are independently selected from PE, PP, PET, PA, and PVDF; 2) When the inner diameter of the flexible composite pipe is 160 mm to less than 480 mm, the material of the inner layer is selected from TPU, TPE, EPDM, styrene-butadiene rubber, nitrile rubber, and silicone rubber, and the material of the outer layer is selected from PE, PP, PET, PA, and PVDF; 3) When the inner diameter of the flexible composite pipe is greater than or equal to 480 mm, the materials of the inner layer and the outer layer are independently selected from TPU, TPE, EPDM, styrene-butadiene rubber, nitrile rubber, and silicone rubber.

6. The flexible composite pipe according to any one of claims 1 to 5, wherein, The thickness of the inner layer is 1 to 10 mm; and / or The number of winding layers of the fiber tape is 2 to 10 layers; and / or The thickness of the outer layer is 1 to 10 mm.

7. The flexible composite pipe according to any one of claims 1 to 5, wherein, The fibers in the reinforcing layer are selected from glass fibers, carbon fibers, aramid fibers, basalt fibers, ultra-high molecular weight polyethylene fibers, and steel wires; and / or The weight percentage of the fibers in the fiber tape is 40% to 60%; and / or The fiber tape is formed by the following steps: 1) Mixing the components of the elastomeric adhesive to prepare elastomeric adhesive particles; 2) Impregnating the fibers: impregnating the fibers in the melt of the elastomeric adhesive, and forming a fiber tape after extrusion and cooling.

8. The flexible composite pipe according to claim 7, wherein, The step of impregnating the fibers is carried out in a continuous fiber impregnating machine, the width of the flat-laid fibers is 100 to 200 mm, and the impregnating temperature is 230 to 270 °C; and / or The thickness of the fiber tape is 0.05 to 0.5 mm.

9. A method for preparing the flexible composite pipe according to any one of claims 1 to 8, which comprises the following steps: i) Extruding the inner layer using a fiber tape winding extruder; ii) Winding a preheated fiber tape on the outer wall of the inner layer at an angle of 45 to 75° with the center of the pipe before the inner layer is cooled, and the number of winding layers is 2 to 10 layers, so as to form a reinforcing layer; iii) Extruding the outer layer, which is sleeved on the surface of the fiber tape, and cooling to obtain a flexible composite pipe, The fiber tape is formed by the following steps: 1) Mixing the components of the elastomeric adhesive to prepare elastomeric adhesive particles; 2) Impregnating the fibers: impregnating the fibers in the melt of the elastomeric adhesive, and forming a fiber tape after extrusion and cooling.

10. The method for preparing a flexible composite pipe according to claim 9, In step ii), the prestress during winding the fiber tape is 1 to 50 N.

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