A polyethylene composite tape for long-distance pipelines and its preparation method

Abstract

The application relates to the technical field of steel pipeline protection, in particular to a polyethylene composite tape for long-distance pipeline and a preparation method thereof. The polyethylene composite tape for long-distance pipeline comprises a polyolefin base material and a glue layer coated on the surface of the polyolefin base material; the raw materials of the glue layer comprise: ethylene-propylene-diene rubber, low-density polyethylene, ethylene-octene copolymer, maleic anhydride grafted polyethylene, lubricant, nano silicon dioxide and antioxidant; and the raw materials of the polyolefin base material comprise: high-density polyethylene, ethylene-propylene-diene rubber, hyperbranched polyamide ester, graphene oxide, urea-formaldehyde resin, antioxidant, ultraviolet stabilizer and silane coupling agent. The application can meet the working condition requirements of on-site joint repairing, effectively enhance the lap shear strength, has excellent peeling strength, effectively solves the interface debonding problem under the stress of the curved pipe arc surface, and the preparation method is simple and suitable for large-scale popularization and application.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steel pipeline protection, in particular to a polyethylene composite tape for long-distance pipeline and a preparation method thereof. BACKGROUND

[0002] In long-distance oil and gas pipeline engineering, for the corrosion protection of steel pipelines, the coating operation of the outer anti-corrosion layer of the hot-bending elbow pipe is more difficult due to the particularity of its shape, and it is often a weak link of the outer anti-corrosion layer of the entire pipeline.

[0003] The corrosion protection performance of the steel pipeline is directly related to the service life and safety of the pipeline. At present, the outer corrosion protection of the hot-bending elbow pipe mainly relies on epoxy coating, polyethylene adhesive tape and other materials, but it is significantly affected by environmental humidity, and there are problems such as high curing internal stress and easy failure of the bonding interface. The joint repair link has long been facing the risks of mismatched coating performance and joint failure, becoming a weak link of pipeline corrosion protection. In addition, the compatibility of EVA-based hot melt adhesive with polyethylene base material is poor, and the peel strength decays significantly during long-term service, which is prone to debonding due to soil stress or temperature alternation.

[0004] At present, a polyethylene composite tape for elbow pipe corrosion protection and steel pipe joint repair has appeared in the market. The polyethylene composite tape is composed of a double-layer structure, one layer is a high-density polyolefin base material crosslinked by radiation, and the other layer is a polyolefin adhesive. However, when the polyethylene composite tape is used in joint repair technology construction, the performance difference between the elbow pipe corrosion layer and the straight pipe section is very large due to insufficient material ductility or uneven thermal shrinkage. The peel strength of the elbow joint repair thermal shrinkage tape decreases significantly due to local stress concentration, becoming a preferential corrosion area.

[0005] Therefore, there are significant shortcomings in the adaptability of elbow pipe corrosion protection materials, the bonding strength of the joint interface and the construction reliability, which need to be solved urgently. SUMMARY

[0006] The present application relates to the technical field of steel pipeline protection, in particular to a polyethylene composite tape for long-distance pipeline and a preparation method thereof.

[0007] A polyethylene composite tape for long-distance pipeline, comprising a polyolefin base material and an adhesive layer coated on the surface of the polyolefin base material.

[0008] The raw materials of the adhesive layer include, by mass fraction, 20-40 parts of EPDM, 40-60 parts of LDPE, 5-15 parts of ethylene-octene copolymer, 1-10 parts of maleic anhydride grafted polyethylene, 1-2 parts of lubricant, 1-2 parts of nano-silicon dioxide, and 1-3 parts of antioxidant.

[0009] The raw material of the polyolefin base material includes, by mass fraction: 5-15 parts of ethylene-propylene-diene rubber, 40-60 parts of high-density polyethylene, 5-10 parts of hyperbranched polyamide ester, 1-2 parts of graphene oxide, 0.5-1 part of urea-formaldehyde resin, 1-3 parts of antioxidant, 0.1-1 part of ultraviolet stabilizer, and 1 part of silane coupling agent.

[0010] Preferably, the thickness ratio of the polyolefin base material to the adhesive layer is 1-2:0.5-1.

[0011] Preferably, the density of the high-density polyethylene is 0.95-0.98 g / cm 3 .

[0012] Preferably, the density of the low-density polyethylene is 0.923-0.927 g / cm 3 .

[0013] Preferably, the ultraviolet stabilizer is a hindered amine light stabilizer, preferably light stabilizer 944.

[0014] Preferably, the maleic anhydride grafting rate of the maleic anhydride grafted polyethylene is 1.5-2%.

[0015] Preferably, the antioxidant is antioxidant 1010 or / and antioxidant 1076.

[0016] Preferably, the lubricant includes calcium stearate and ethylene bis-stearamide, and the mass ratio of calcium stearate to ethylene bis-stearamide is 1:0.1-0.5.

[0017] The preparation method of the polyethylene composite tape for long-distance pipelines includes the following steps:

[0018] S1, premix ethylene-propylene-diene rubber, high-density polyethylene, hyperbranched polyamide ester, graphene oxide, urea-formaldehyde resin, antioxidant, and ultraviolet stabilizer, and extrude at 160-200°C, then cool to room temperature, etch the surface on one side with high-pressure water jet for 2-5 seconds at a water flow pressure of 50-150 MPa and a water flow speed of 3-5 m / s, spray the surface with an ethanol solution containing silane coupling agent, pre-dry at 80-100°C, and perform electron beam radiation treatment to obtain a polyethylene base material.

[0019] The three-dimensional dendritic molecular chains of the hyperbranched polyamide ester form a multi-hydrogen bond network with the lamellar graphene oxide and the urea-formaldehyde resin through the hydroxyl groups, and cooperate with the ethylene-propylene-diene rubber to maintain stable corrosion resistance under dynamic stress on the curved surface of the elbow.

[0020] S2, mix ethylene-propylene-diene rubber, low-density polyethylene, ethylene-octene copolymer, maleic anhydride grafted polyethylene, lubricant, nano-silicon dioxide, and antioxidant uniformly, and melt-extrude to coat the surface on one side of the polyethylene base material after high-pressure water jet etching, and vacuum adsorb and cool.

[0021] Preferably, in S1, the irradiation dose during the electron beam radiation treatment is 10-15 kGy.

[0022] Preferably, in S1, the silane coupling agent-containing ethanol solution is prepared from the silane coupling agent and anhydrous ethanol at a mass ratio of 1:5-10.

[0023] Beneficial effects:

[0024] The present application utilizes the compounding and blending of the ethylene-propylene-diene rubber, the low-density polyethylene and the maleic anhydride grafted polyethylene, the anhydride groups of the maleic anhydride grafted polyethylene form a reinforcing phase in the system, which can effectively avoid the peeling failure caused by thermal expansion mismatch, and the ethylene-octene copolymer can effectively resist the stress-induced fatigue cracking.

[0025] The present application utilizes the compounding and blending of the ethylene-propylene-diene rubber, the low-density polyethylene and the maleic anhydride grafted polyethylene, the anhydride groups of the maleic anhydride grafted polyethylene form a reinforcing phase in the system, which can effectively avoid the peeling failure caused by thermal expansion mismatch, and the ethylene-octene copolymer can effectively resist the stress-induced fatigue cracking.

[0026] The present application can meet the working condition requirements of field joint coating, effectively enhance the lap shear strength, and has excellent peeling strength, effectively solving the interface debonding problem under the stress of the curved pipe arc surface. The present application can ensure the stability of the adhesive layer in the production of composite tape and pipe joint coating, eliminate the difference in corrosion prevention quality between curved pipes and straight pipes, and the preparation method is simple, suitable for large-scale popularization and application. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 The tensile strength and lap shear strength of the polyethylene composite tape obtained in Example 5 and Comparative Examples 1-3 are compared.

[0028] Figure 2 The peeling strength of the polyethylene composite tape obtained in Example 5 and Comparative Examples 1-3 is compared.

[0029] Figure 3 The peeling strength of the polyethylene composite tape obtained in Example 5 and Comparative Examples 1-3 is compared. DETAILED DESCRIPTION

[0030] The present application will be further described below in conjunction with specific examples.

[0031] The high-density polyethylene used below is sourced from Jilin Petrochemical, grade HDPE HA7260, with a density of 0.957 g / cm³. 3 The low-density polyethylene used below is sourced from Yanshan Petrochemical, grade LDPE LD104, with a density of 0.925 g / cm³. 3 The EPDM rubber used below is sourced from Dow Chemical Company, USA, and its brand name is EPDM IP 3430. The hyperbranched polyamide ester used below is commercially available as Hybrane® PS 2550. The ethylene-octene copolymer used below is sourced from Dow Chemical Company, USA, and its brand name is ENGAGE™ POE8842. The maleic anhydride-grafted polyethylene used below was purchased from Wuhan Mouxiang Kejie Biotechnology Co., Ltd., with a maleic anhydride grafting rate of 1.76%. The urea-formaldehyde resin used below was purchased from Jinan Mouguang Chemical Co., Ltd.

[0032] Example 1

[0033] A polyethylene composite tape for long-distance pipelines includes: a polyolefin substrate with a thickness of 1 mm, and an adhesive layer (with a thickness of 0.5 mm) coated on the surface of the polyolefin substrate.

[0034] The adhesive layer consists of the following raw materials: 20g EPDM rubber, 40g low-density polyethylene, 5g ethylene-octene copolymer, 1g maleic anhydride grafted polyethylene, 1g lubricant (composed of calcium stearate and ethylene bis-stearamide in a mass ratio of 1:0.1), 1g nano-silica, and 1g antioxidant 1076. The polyolefin substrate consists of the following raw materials: 5g EPDM rubber, 40g high-density polyethylene, 5g hyperbranched polyamide ester, 1g graphene oxide, 0.5g urea-formaldehyde resin, 1g antioxidant 1010, 0.1g light stabilizer 944, and 1g KH560 coupling agent.

[0035] The preparation method of the above-mentioned polyethylene composite belt for long-distance pipelines includes the following steps:

[0036] S1. Ethylene propylene diene monomer (EPDM) rubber, high-density polyethylene (HDPE), hyperbranched polyamide ester, graphene oxide, urea-formaldehyde resin, antioxidant 1010, and light stabilizer 944 are premixed in a mixer and then extruded into a twin-screw extruder at an extrusion temperature of 160°C, then cooled to room temperature. One side of the surface is etched with high-pressure water jet for 2 seconds at a water pressure of 50 MPa and a water velocity of 3 m / s. The surface after high-pressure water jet etching is then sprayed with an ethanol solution containing KH560 coupling agent (the mass ratio of silane coupling agent to anhydrous ethanol is 1:5). The surface is pre-dried at 80°C, treated with electron beam radiation (irradiation dose of 10 kGy), and dried to obtain a polyethylene substrate.

[0037] S2. Mix EPDM rubber, low-density polyethylene, ethylene-octene copolymer, maleic anhydride grafted polyethylene, lubricant, nano silica, and antioxidant 1076 evenly, feed them into a twin-screw extruder for melt extrusion, and then coat them onto one side of the polyethylene substrate after high-pressure water jet etching at a coating temperature of 190℃; vacuum adsorption cooling is performed with the wind speed controlled at 0.5m / s.

[0038] Example 2

[0039] A polyethylene composite tape for long-distance pipelines includes: a 2mm thick polyolefin substrate and an adhesive layer (1mm thick) coated on the surface of the polyolefin substrate.

[0040] The adhesive layer consists of the following raw materials: 40g of EPDM rubber, 60g of low-density polyethylene, 15g of ethylene-octene copolymer, 10g of maleic anhydride-grafted polyethylene, 2g of lubricant (composed of calcium stearate and ethylene bis-stearamide in a mass ratio of 1:0.5), 2g of nano-silica, and 3g of antioxidant 1076. The polyolefin substrate consists of the following raw materials: 15g of EPDM rubber, 60g of high-density polyethylene, 10g of hyperbranched polyamide ester, 2g of graphene oxide, 1g of urea-formaldehyde resin, 3g of antioxidant 1010, 1g of light stabilizer 944, and 1g of KH560 coupling agent.

[0041] The preparation method of the above-mentioned polyethylene composite belt for long-distance pipelines includes the following steps:

[0042] S1. Ethylene propylene diene monomer (EPDM) rubber, high-density polyethylene (HDPE), hyperbranched polyamide ester, graphene oxide, urea-formaldehyde resin, antioxidant 1010, and light stabilizer 944 are premixed in a mixer and then extruded into a twin-screw extruder at an extrusion temperature of 200°C, which is then cooled to room temperature. One side of the surface is etched with high-pressure water jet for 5 seconds at a water pressure of 150 MPa and a water flow velocity of 5 m / s. An ethanol solution containing KH560 coupling agent (mass ratio of silane coupling agent to anhydrous ethanol is 1:10) is sprayed onto the surface after high-pressure water jet etching. The surface is then pre-dried at 100°C, treated with electron beam radiation (irradiation dose of 15 kGy), and dried to obtain a polyethylene substrate.

[0043] S2. Mix EPDM rubber, low-density polyethylene, ethylene-octene copolymer, maleic anhydride grafted polyethylene, lubricant, nano silica, and antioxidant 1076 evenly, feed them into a twin-screw extruder for melt extrusion, and then coat them onto one side of the polyethylene substrate after high-pressure water jet etching at a coating temperature of 200℃; vacuum adsorption cooling is performed with the wind speed controlled at 0.8m / s.

[0044] Example 3

[0045] A polyethylene composite tape for long-distance pipelines includes: a polyolefin substrate with a thickness of 1.5 mm, and an adhesive layer (0.75 mm thick) coated on the surface of the polyolefin substrate.

[0046] The adhesive layer consists of the following raw materials: 25g EPDM rubber, 55g low-density polyethylene, 12g ethylene-octene copolymer, 2g maleic anhydride grafted polyethylene, 1.3g lubricant (composed of calcium stearate and ethylene bis-stearamide in a mass ratio of 1:0.4), 1.8g nano-silica, and 1.5g antioxidant 1076. The polyolefin substrate consists of the following raw materials: 12g EPDM rubber, 45g high-density polyethylene, 7g hyperbranched polyamide ester, 1.7g graphene oxide, 0.7g urea-formaldehyde resin, 2.5g antioxidant 1076, 0.3g light stabilizer 944, and 1g KH560 coupling agent.

[0047] The preparation method of the above-mentioned polyethylene composite belt for long-distance pipelines includes the following steps:

[0048] S1. Ethylene propylene diene monomer (EPDM) rubber, high-density polyethylene (HDPE), hyperbranched polyamide ester, graphene oxide, urea-formaldehyde resin, antioxidant 1076, and light stabilizer 944 are premixed in a mixer and then extruded into a twin-screw extruder at an extrusion temperature of 190°C, then cooled to room temperature. One side of the surface is etched by high-pressure water jet for 3 seconds at a water pressure of 120 MPa and a water velocity of 3.5 m / s. The surface after high-pressure water jet etching is then sprayed with an ethanol solution containing KH560 coupling agent (the mass ratio of silane coupling agent to anhydrous ethanol is 1:9). The surface is pre-dried at 85°C, treated with electron beam radiation (irradiation dose of 13 kGy), and dried to obtain a polyethylene substrate.

[0049] S2. Mix EPDM rubber, low-density polyethylene, ethylene-octene copolymer, maleic anhydride grafted polyethylene, lubricant, nano silica, and antioxidant 1076 evenly, feed them into a twin-screw extruder for melt extrusion, and then coat them onto one side of the polyethylene substrate after high-pressure water jet etching at a coating temperature of 192℃; vacuum adsorption cooling is performed with the wind speed controlled at 0.7m / s.

[0050] Example 4

[0051] A polyethylene composite tape for long-distance pipelines includes: a polyolefin substrate with a thickness of 1.5 mm, and an adhesive layer (0.75 mm thick) coated on the surface of the polyolefin substrate.

[0052] The adhesive layer consists of the following raw materials: 35g EPDM rubber, 45g low-density polyethylene, 8g ethylene-octene copolymer, 8g maleic anhydride grafted polyethylene, 1.7g lubricant (composed of calcium stearate and ethylene bis-stearamide in a mass ratio of 1:0.2), 1.2g nano-silica, and 2.5g antioxidant 1076. The polyolefin substrate consists of the following raw materials: 8g EPDM rubber, 55g high-density polyethylene, 9g hyperbranched polyamide ester, 1.3g graphene oxide, 0.8g urea-formaldehyde resin, 1.5g antioxidant 1076, 0.7g light stabilizer 944, and 1g KH560 coupling agent.

[0053] The preparation method of the above-mentioned polyethylene composite belt for long-distance pipelines includes the following steps:

[0054] S1. Ethylene propylene diene monomer (EPDM) rubber, high-density polyethylene (HDPE), hyperbranched polyamide ester, graphene oxide, urea-formaldehyde resin, antioxidant 1076, and light stabilizer 944 are premixed in a mixer and then extruded into a twin-screw extruder at an extrusion temperature of 170°C, then cooled to room temperature. One side of the surface is etched with high-pressure water jet for 4 seconds at a water pressure of 80 MPa and a water velocity of 4.5 m / s. The surface after high-pressure water jet etching is then sprayed with an ethanol solution containing KH560 coupling agent (the mass ratio of silane coupling agent to anhydrous ethanol is 1:7). The surface is pre-dried at 95°C, treated with electron beam radiation (irradiation dose of 11 kGy), and dried to obtain a polyethylene substrate.

[0055] S2. Mix EPDM rubber, low-density polyethylene, ethylene-octene copolymer, maleic anhydride grafted polyethylene, lubricant, nano silica, and antioxidant 1076 evenly, feed them into a twin-screw extruder for melt extrusion, and then coat them onto one side of the polyethylene substrate after high-pressure water jet etching at a coating temperature of 198℃; vacuum adsorption cooling is performed with the wind speed controlled at 0.6m / s.

[0056] Example 5

[0057] A polyethylene composite tape for long-distance pipelines includes: a polyolefin substrate with a thickness of 1.5 mm, and an adhesive layer (0.75 mm thick) coated on the surface of the polyolefin substrate.

[0058] The adhesive layer consists of the following raw materials: 30g EPDM rubber, 50g low-density polyethylene, 10g ethylene-octene copolymer, 5g maleic anhydride grafted polyethylene, 1.5g lubricant (composed of calcium stearate and ethylene bis-stearamide in a mass ratio of 1:0.3), 1.5g nano silica, and 2g antioxidant 1010. The polyolefin substrate consists of the following raw materials: 10g EPDM rubber, 50g high-density polyethylene, 8g hyperbranched polyamide ester, 1.5g graphene oxide, 0.75g urea-formaldehyde resin, 2g antioxidant 1010, 0.5g light stabilizer 944, and 1g KH560 coupling agent.

[0059] The preparation method of the above-mentioned polyethylene composite belt for long-distance pipelines includes the following steps:

[0060] S1. Ethylene propylene diene monomer (EPDM) rubber, high-density polyethylene (HDPE), hyperbranched polyamide ester, graphene oxide, urea-formaldehyde resin, antioxidant 1010, and light stabilizer 944 are premixed in a mixer and then extruded into a twin-screw extruder at an extrusion temperature of 180°C, then cooled to room temperature. One side of the surface is etched with high-pressure water jet for 4 seconds at a water pressure of 100 MPa and a water velocity of 4 m / s. The surface after high-pressure water jet etching is then sprayed with an ethanol solution containing KH560 coupling agent (the mass ratio of silane coupling agent to anhydrous ethanol is 1:8). The surface is pre-dried at 90°C, treated with electron beam radiation (irradiation dose of 12 kGy), and dried to obtain a polyethylene substrate.

[0061] S2. Mix EPDM rubber, low-density polyethylene, ethylene-octene copolymer, maleic anhydride grafted polyethylene, lubricant, nano silica, and antioxidant 1010 evenly, feed them into a twin-screw extruder for melt extrusion, and then coat them onto one side of the polyethylene substrate after high-pressure water jet etching. The coating temperature is 195℃. Vacuum adsorption cooling is performed, and the wind speed is controlled at 0.65m / s.

[0062] Comparative Example 1

[0063] A polyethylene composite tape for long-distance pipelines includes: a polyolefin substrate with a thickness of 1.5 mm, and an adhesive layer (0.75 mm thick) coated on the surface of the polyolefin substrate.

[0064] The adhesive layer consists of the following raw materials: 30g EPDM rubber, 50g low-density polyethylene, 10g ethylene-octene copolymer, 5g maleic anhydride grafted polyethylene, 1.5g lubricant (composed of calcium stearate and ethylene bis-stearamide in a mass ratio of 1:0.3), 1.5g nano silica, and 2g antioxidant 1010. The polyolefin substrate consists of the following raw materials: 10g EPDM rubber, 50g high-density polyethylene, 8g hyperbranched polyamide ester, 1.5g graphene oxide, 0.75g urea-formaldehyde resin, 2g antioxidant 1010, 0.5g light stabilizer 944, and 1g KH560 coupling agent.

[0065] The preparation method of the above-mentioned polyethylene composite belt for long-distance pipelines includes the following steps:

[0066] S1. Ethylene propylene diene monomer (EPDM) rubber, high-density polyethylene (HDPE), hyperbranched polyamide ester, graphene oxide, urea-formaldehyde resin, antioxidant 1010, and light stabilizer 944 are premixed in a mixer and then extruded into a twin-screw extruder at an extrusion temperature of 180°C, then cooled to room temperature. One side of the surface is etched with high-pressure water jet for 4 seconds at a water pressure of 100 MPa and a water flow rate of 4 m / s. An ethanol solution containing KH560 coupling agent (the mass ratio of silane coupling agent to anhydrous ethanol is 1:8) is sprayed onto the surface after high-pressure water jet etching. The surface is then pre-dried at 90°C to obtain a polyethylene substrate.

[0067] S2. Mix EPDM rubber, low-density polyethylene, ethylene-octene copolymer, maleic anhydride grafted polyethylene, lubricant, nano silica, and antioxidant 1010 evenly, feed them into a twin-screw extruder for melt extrusion, and then coat them onto one side of the polyethylene substrate after high-pressure water jet etching. The coating temperature is 195℃. Vacuum adsorption cooling is performed, and the wind speed is controlled at 0.65m / s.

[0068] Comparative Example 2

[0069] A polyethylene composite tape for long-distance pipelines includes: a polyolefin substrate with a thickness of 1.5 mm, and an adhesive layer (0.75 mm thick) coated on the surface of the polyolefin substrate.

[0070] The adhesive layer consists of the following raw materials: 30g of EPDM rubber, 50g of low-density polyethylene, 10g of ethylene-octene copolymer, 5g of maleic anhydride-grafted polyethylene, 1.5g of lubricant (composed of calcium stearate and ethylene bis-stearamide in a mass ratio of 1:0.3), 1.5g of nano-silica, and 2g of antioxidant 1010. The polyolefin substrate consists of the following raw materials: 18g of EPDM rubber, 50g of high-density polyethylene, 1.5g of graphene oxide, 0.75g of urea-formaldehyde resin, 2g of antioxidant 1010, 0.5g of light stabilizer 944, and 1g of KH560 coupling agent.

[0071] The preparation method of the above-mentioned polyethylene composite belt for long-distance pipelines includes the following steps:

[0072] S1. Ethylene propylene diene monomer (EPDM) rubber, high-density polyethylene (HDPE), graphene oxide, urea-formaldehyde resin, antioxidant 1010, and light stabilizer 944 are premixed in a mixer and then extruded into a twin-screw extruder at an extrusion temperature of 180°C, then cooled to room temperature. One side of the surface is etched with high-pressure water jet for 4 seconds at a water pressure of 100 MPa and a water velocity of 4 m / s. The surface after high-pressure water jet etching is then sprayed with an ethanol solution containing KH560 coupling agent (the mass ratio of silane coupling agent to anhydrous ethanol is 1:8). The surface is pre-dried at 90°C, treated with electron beam radiation (irradiation dose of 12 kGy), and dried to obtain a polyethylene substrate.

[0073] S2. Mix EPDM rubber, low-density polyethylene, ethylene-octene copolymer, maleic anhydride grafted polyethylene, lubricant, nano silica, and antioxidant 1010 evenly, feed them into a twin-screw extruder for melt extrusion, and then coat them onto one side of the polyethylene substrate after high-pressure water jet etching. The coating temperature is 195℃. Vacuum adsorption cooling is performed, and the wind speed is controlled at 0.65m / s.

[0074] Comparative Example 3

[0075] A polyethylene composite tape for long-distance pipelines includes: a polyolefin substrate with a thickness of 1.5 mm, and an adhesive layer (0.75 mm thick) coated on the surface of the polyolefin substrate.

[0076] The adhesive layer consists of the following raw materials: 30g EPDM rubber, 50g low-density polyethylene, 10g ethylene-octene copolymer, 5g maleic anhydride grafted polyethylene, 1.5g lubricant (composed of calcium stearate and ethylene bis-stearamide in a mass ratio of 1:0.3), 1.5g nano silica, and 2g antioxidant 1010. The polyolefin substrate consists of the following raw materials: 10g EPDM rubber, 50g high-density polyethylene, 8g hyperbranched polyamide ester, 1.5g graphene oxide, 0.75g urea-formaldehyde resin, 2g antioxidant 1010, 0.5g light stabilizer 944, and 1g KH560 coupling agent.

[0077] The preparation method of the above-mentioned polyethylene composite belt for long-distance pipelines includes the following steps:

[0078] S1. Premix EPDM rubber, high-density polyethylene, hyperbranched polyamide ester, graphene oxide, urea-formaldehyde resin, antioxidant 1010, and light stabilizer 944 in a mixer, then extrude them in a twin-screw extruder at 180°C and allow them to cool to room temperature. Spray an ethanol solution containing KH560 coupling agent (silane coupling agent and anhydrous ethanol in a mass ratio of 1:8) onto one side surface, pre-dry at 90°C, treat with electron beam radiation (irradiation dose of 12 kGy), and dry to obtain a polyethylene substrate.

[0079] S2. Mix EPDM rubber, low-density polyethylene, ethylene-octene copolymer, maleic anhydride grafted polyethylene, lubricant, nano silica, and antioxidant 1010 evenly, and feed it into a twin-screw extruder for melt extrusion. Immediately coat the polyethylene substrate with the side sprayed with KH560 coupling agent at a coating temperature of 195℃. Vacuum adsorption cooling is performed with the air velocity controlled at 0.65m / s.

[0080] The tensile strength of the polyethylene composite tapes obtained in Example 5 and Comparative Examples 1-3 was determined with reference to GB / T 1040.2-2022 "Determination of tensile properties of plastics - Part 2: Test conditions for molded and extruded plastics".

[0081] The lap shear strength of the polyethylene composite tapes obtained in Example 5 and Comparative Examples 1-3 was determined in accordance with GB / T 7124-2008 "Determination of tensile shear strength of adhesives (rigid material to rigid material)".

[0082] The peel strength of the polyethylene composite tapes obtained in Example 5 and Comparative Examples 1-3 was determined with reference to GB / T 2790-1995 "Test Method for 180° Peel Strength of Adhesives - Flexible Materials vs. Rigid Materials" and SY / T0315 "Technical Specification for Fusion Bonded Epoxy Powder Coating of Steel Pipelines".

[0083] like Figure 1 and Figure 2 As shown, the polyethylene composite tape obtained in Example 5 has the highest tensile strength, lap shear strength, and peel strength, which are superior to those of Comparative Examples 1-3 (P<0.05).

[0084] The polyethylene composite tapes obtained in Example 5 and Comparative Examples 1-3 were cold-wrapped onto the bends using a hot-wrapping method. The bends with the polyethylene composite tapes (without edge sealing) were then immersed in a constant temperature water bath at 50±3℃ for a period of time. After that, the samples were removed from the water bath and subjected to peel strength testing.

[0085] like Figure 3 As shown, the polyethylene composite tape obtained in Example 5, after being treated with a hot water bath, still maintained the highest peel strength, which was superior to that of Comparative Examples 1-3 (P<0.05).

[0086] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A polyethylene composite tape for long distance pipelines, characterized by, The polyolefin base material and the adhesive layer coated on the surface of the polyolefin base material; The raw materials of the adhesive layer include, by mass fraction, 20-40 parts of ethylene-propylene-diene rubber, 40-60 parts of low-density polyethylene, 5-15 parts of ethylene-octene copolymer, 1-10 parts of maleic anhydride grafted polyethylene, 1-2 parts of lubricant, 1-2 parts of nano-silicon dioxide, and 1-3 parts of antioxidant. The raw materials of the polyolefin base material include, by mass fraction, 5-15 parts of ethylene-propylene-diene rubber, 40-60 parts of high-density polyethylene, 5-10 parts of hyperbranched polyamide ester, 1-2 parts of graphene oxide, 0.5-1 part of urea-formaldehyde resin, 1-3 parts of antioxidant, 0.1-1 part of ultraviolet stabilizer, and 1 part of silane coupling agent. The polyolefin base material is prepared by the following steps: S1, the ethylene-propylene-diene rubber, high-density polyethylene, hyperbranched polyamide ester, graphene oxide, urea-formaldehyde resin, antioxidant, and ultraviolet stabilizer are premixed, extruded at 160-200 DEG C, cooled to room temperature, etched on one side surface by high-pressure water jet for 2-5 s, the water flow pressure is 50-150 MPa, the water flow speed is 3-5 m / s, the surface is sprayed with an ethanol solution containing silane coupling agent, pre-dried at 80-100 DEG C, treated by electron beam radiation, and dried to obtain the polyethylene base material; S2, the ethylene-propylene-diene rubber, low-density polyethylene, ethylene-octene copolymer, maleic anhydride grafted polyethylene, lubricant, nano-silicon dioxide, and antioxidant are uniformly mixed, melt-extruded and coated on the side surface of the polyethylene base material etched by high-pressure water jet, and vacuum adsorbed and cooled.

2. The polyethylene composite tape for long distance pipeline according to claim 1, wherein The thickness ratio of the polyolefin base material to the adhesive layer is 1-2:0.5-1.

3. The polyethylene composite tape for long distance pipeline according to claim 1, wherein The high density polyethylene has a density of 0.95-0.98 g / cm 3 .

4. The polyethylene composite tape for long distance pipeline according to claim 1, wherein The low density polyethylene has a density of 0.923-0.927 g / cm 3 .

5. The polyethylene composite tape for long distance pipeline according to claim 1, wherein The ultraviolet stabilizer is a hindered amine light stabilizer.

6. The polyethylene composite tape for long distance pipeline as claimed in claim 1, wherein The maleic anhydride grafting rate of the maleic anhydride grafted polyethylene is 1.5-2%.

7. The polyethylene composite tape for long distance pipeline as claimed in claim 1, wherein The antioxidant is antioxidant 1010 or / and antioxidant 1076.

8. The polyethylene composite tape for long distance pipeline as claimed in claim 1, wherein The lubricant includes calcium stearate and ethylene bis-stearamide, and the mass ratio of calcium stearate to ethylene bis-stearamide is 1:0.1-0.

5.

9. A method of producing a polyethylene composite tape for long distance pipelines as claimed in any one of claims 1 to 8, characterized in that, The polyolefin base material is prepared by the following steps: S1, the ethylene-propylene-diene rubber, high-density polyethylene, hyperbranched polyamide ester, graphene oxide, urea-formaldehyde resin, antioxidant, and ultraviolet stabilizer are premixed, extruded at 160-200 DEG C, cooled to room temperature, etched on one side surface by high-pressure water jet for 2-5 s, the water flow pressure is 50-150 MPa, the water flow speed is 3-5 m / s, the surface is sprayed with an ethanol solution containing silane coupling agent, pre-dried at 80-100 DEG C, treated by electron beam radiation, and dried to obtain the polyethylene base material; S2, the ethylene-propylene-diene rubber, low-density polyethylene, ethylene-octene copolymer, maleic anhydride grafted polyethylene, lubricant, nano-silicon dioxide, and antioxidant are uniformly mixed, melt-extruded and coated on the side surface of the polyethylene base material etched by high-pressure water jet, and vacuum adsorbed and cooled.

10. The method for preparing polyethylene composite tape for long-distance pipelines according to claim 9, characterized in that, In S1, the irradiation dose during the electron beam radiation treatment is 10-15 kGy.

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