Oxygen-barrier super-heat-conduction and heat-resistance polyethylene pipe and preparation method thereof

Abstract

The invention discloses an oxygen-resistant superconductive heat-resistant polyethylene pipe and a preparation method thereof. The heat-resistant polyethylene pipe is formed by co-extruding and compounding an oxygen-resistant outer layer and a hydrophobic inner layer, the oxygen barrier outer layer is prepared from PE-RT resin, a multifunctional oxygen barrier, a lubricant, an antioxidant and a pigment according to a certain ratio, and the hydrophobic inner layer is prepared from PE-RT resin, stearic acid coordination metal salt and an antioxidant according to a certain ratio. According to the invention, the problems that polyvinyl alcohol is hydrophilic and is easy to hydrolyze at high temperature when being independently used as an oxygen barrier layer are solved, the problem that polyvinyl alcohol is incompatible with the PE-RT raw material is also solved, and the oxygen barrier property and the mechanical property of the heat-resistant polyethylene pipe are ensured.

Description

Technical Field

[0001] This invention relates to the field of heat-resistant polyethylene pipe production technology, specifically to an oxygen-barrier type superconducting heat-resistant polyethylene pipe and its preparation method. Background Technology

[0002] PE-RT (heat-resistant polyethylene) pipes have become the mainstream choice for heating systems due to their good flexibility and the ability to be heat-fused. However, their high oxygen permeability means that, during long-term operation, the infiltrated oxygen can corrode metal components within the system (such as radiators and boilers), promote microbial growth, reduce thermal efficiency, and affect the system's lifespan.

[0003] Currently, the common solution is to add an EVOH (ethylene-vinyl alcohol copolymer) oxygen barrier layer to the pipe. Although the barrier effect is good, there are obvious shortcomings: ① EVOH has poor compatibility with PE-RT, and is prone to delamination and wrinkling when the pipe is bent or the temperature changes, resulting in oxygen barrier failure; ② The cost is high, increasing the cost by about 30%-50%; ③ EVOH is difficult to recycle and is not environmentally friendly.

[0004] Polyvinyl alcohol (PVA) possesses inherently high oxygen barrier properties due to its hydroxyl-rich molecular chain, theoretically superior to EVOH, and also offers significant environmental advantages due to its low cost and biodegradability. However, PVA is a hydrophilic material with extremely poor compatibility with hydrophobic PE-RT; direct blending will result in phase separation, severely impacting mechanical properties and failing to meet engineering requirements. Achieving effective compatibility between PVA and PE-RT is a key technical bottleneck in improving the overall performance of PE-RT oxygen barrier pipes. Summary of the Invention

[0005] Based on the above-mentioned prior art, the present invention provides an oxygen barrier type superconducting heat-resistant polyethylene pipe and its preparation method. The present invention solves the problems of polyvinyl alcohol being hydrophilic as an oxygen barrier layer and being easily hydrolyzed at high temperatures, and also solves the problem of incompatibility between polyvinyl alcohol and PE-RT raw materials, thus ensuring the oxygen barrier properties and mechanical properties of the heat-resistant polyethylene pipe.

[0006] The technical solution adopted to achieve the above-mentioned objectives of this invention is as follows: An oxygen-barrier type superconducting heat-resistant polyethylene pipe is made by co-extrusion composite of an oxygen-barrier outer layer and a hydrophobic inner layer. The multifunctional outer layer is made from the following raw materials in parts by weight: 60-80 parts of PE-RT resin 5-10 parts of multifunctional oxygen barrier 3-7 parts lubricant 1-2 parts antioxidant 1-3 parts pigment; The multifunctional oxygen barrier is a compatibility-modified polyvinyl alcohol / graphene oxide composite. The hydrophobic inner layer is prepared from the following raw materials in parts by weight: 60-80 parts of PE-RT resin 3-5 parts of stearic acid coordination metal salt 1-2 parts antioxidant.

[0007] Furthermore, the preparation method of the aforementioned multifunctional oxygen barrier agent is as follows: 1. Graphene oxide is dispersed in a mixed solvent of ethanol and deionized water, a polyphenolic surface modifier is added, and the mixture is heated to 70-90℃. The mixture is reacted at 70-90℃ for 2-6 hours. After the reaction is completed, the mixture is cooled to room temperature, filtered, and the filter cake is washed with methanol and dried to obtain modified graphene oxide. 2. Dissolve polyvinyl alcohol in deionized water at 90-100℃ to obtain a polyvinyl alcohol solution. Cool the polyvinyl alcohol solution to 40-60℃, then add modified graphene oxide, disperse evenly, cool to room temperature, filter, and dry the filter cake to obtain a multifunctional oxygen barrier agent.

[0008] Furthermore, the preparation method of the polyphenol-type surface modifier is as follows: 1. Under room temperature and nitrogen protection, the carboxyl functional group of pergalic acid and the secondary amine group of SCAA86T silane coupling agent undergo an acylation reaction to generate a siloxane monomer. 2. Under nitrogen protection, the tertiary amine group of the siloxane monomer undergoes a quaternization reaction with the chlorine functional group of a chlorinated long-chain alkane with not less than 12 carbon atoms to generate a polyphenolic surface modifier.

[0009] Furthermore, the chlorinated long-chain alkane is selected from at least one of chlorinated hexadecane, chlorinated octadecane, chlorinated tetradecane, and chlorinated dodecane.

[0010] Furthermore, the polyphenol surface modifier is a condensation product of gallic acid and SCA-A86T silane coupling agent.

[0011] Furthermore, the lubricant is selected from at least one of stearamide, calcium stearate, N,N′-ethylene bis-stearamide, and polyethylene wax.

[0012] Furthermore, the antioxidant is selected from at least one of antioxidant 1010, antioxidant 168 and antioxidant 1076.

[0013] Furthermore, the pigment is selected from at least one of titanium dioxide, ultramarine, phthalocyanine blue, and phthalocyanine green.

[0014] Furthermore, the stearic acid coordination metal salt is selected from at least one of zinc stearate and aluminum stearate.

[0015] A method for preparing an oxygen-barrier, superconducting, heat-resistant polyethylene pipe includes the following steps: S1. Mix PE-RT resin, multifunctional oxygen barrier agent, lubricant, antioxidant and pigment evenly to obtain oxygen barrier outer layer compound; S2. Mix PE-RT resin, hydrophobic stearic acid coordination metal salt and antioxidant evenly to obtain hydrophobic inner layer compound; S3. The oxygen-barrier outer layer compound is added to the first extruder for melt extrusion, and the hydrophobic inner layer compound is added to the second extruder for melt extrusion. Then, the mixture is co-extruded through a co-extrusion die and cooled to obtain the oxygen-barrier superconducting heat-resistant polyethylene pipe.

[0016] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows: 1. This invention modifies the polyvinyl alcohol / graphene oxide composite with a special polyphenolic surface modifier. The resulting multifunctional oxygen barrier agent is added to the outer layer of the heat-resistant polyethylene pipe, which significantly improves the compatibility of polyvinyl alcohol and graphene oxide with the heat-resistant polyethylene. Thus, the oxygen barrier performance of the heat-resistant polyethylene pipe is improved by the well-compatible and dispersed polyvinyl alcohol, and the thermal conductivity of the heat-resistant polyethylene pipe is improved by the well-compatible and dispersed graphene oxide.

[0017] 2. This invention adds polyvinyl alcohol for oxygen barrier. However, since polyvinyl alcohol is hydrophilic and easily hydrolyzed in high-temperature water environments, it is placed on the outer layer for oxygen barrier and the inner hydrophobic layer for water barrier. A hydrophobic stearate metal salt, such as zinc stearate or aluminum stearate, is added to the inner layer of the heat-resistant polyethylene pipe for hydrophobic modification. On the one hand, the hydrophobic stearate metal salt has good hydrophobic properties, ensuring the hydrophobicity of the inner layer of the heat-resistant polyethylene pipe. On the other hand, since the stearate metal salt can coordinate with polyvinyl alcohol, it improves the bonding performance between the oxygen barrier outer layer and the hydrophobic inner layer, thereby improving the strength of the heat-resistant polyethylene pipe.

[0018] 3. The addition of zinc stearate to the inner layer of the heat-resistant polyethylene pipe in this invention can also improve the antibacterial properties of the heat-resistant polyethylene pipe. Detailed Implementation

[0019] The present invention will now be described in detail with reference to specific embodiments, but these embodiments are not to be construed as limiting the scope of protection of the present invention in any sense.

[0020] The sources of the raw materials used in the following examples and comparative examples are as follows: The PE-RT resin was purchased from DAELIM in South Korea, model mMDPE XP9000.

[0021] The graphene oxide was purchased from Merck Sigma-Aldrich, Germany, model number 796034. Polyvinyl alcohol was purchased from Anhui Wanwei High-Tech Materials Co., Ltd., model 1799.

[0022] The preparation method of the polyphenol-type surface modifier (referring to the preparation method of an oxygen-barrier polyvinyl alcohol packaging material in Chinese patent) is as follows: 1. Under nitrogen protection, 1.7 g gallic acid, 2.4 g SCAA86T silane coupling agent, 1.0 g triethylamine, and 50 mL anhydrous dichloromethane were added to a three-necked flask equipped with a water separator. The mixture was stirred at room temperature for 30 min. Then, 20 mL of 1-hydroxybenzotriazole solution (prepared from 1.3 g 1-hydroxybenzotriazole and 20 mL dichloromethane) and 30 mL of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride solution (prepared from 1.9 g 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 30 mL dichloromethane) were added to the three-necked flask. The mixture was stirred at room temperature for 20 h. A 1 mol / L sodium hydroxide aqueous solution was added. The mixture was extracted with dichloromethane, dried over anhydrous magnesium sulfate, filtered, and the solvent was removed by rotary evaporation to obtain the siloxane monomer. 2. Add 3.0g of siloxane monomer and cyclohexane to a three-necked flask. Under nitrogen protection and mechanical stirring, heat to 60℃. After the temperature stabilizes, add 2.0g of 1-chlorooctadecane dropwise to the three-necked flask. Maintain the temperature at 60℃ and stir for 18h. After the reaction is complete, cool and evaporate by rotary evaporation. Wash the residue with ethyl acetate and dry under vacuum to obtain a multifunctional oxygen inhibitor.

[0023] Example 1 An oxygen-barrier type superconducting heat-resistant polyethylene pipe is made by co-extrusion composite of an oxygen-barrier outer layer and a hydrophobic inner layer. The multifunctional outer layer is made from the following raw materials in parts by weight: 60 parts of PE-RT resin 5 parts of multifunctional oxygen barrier EBS 3 copies Antioxidant 1010 0.6 parts Antioxidant 168 0.4 parts 1 part titanium dioxide; The hydrophobic inner layer is prepared from the following raw materials in parts by weight: 60 parts of PE-RT resin 2 parts zinc stearate 1 part aluminum stearate; Antioxidant 1010 0.6 parts Antioxidant 168 0.4 parts The preparation method of the above-mentioned multifunctional oxygen inhibitor is as follows: 1. Disperse 50g of graphene oxide in a mixed solvent of 80ml ethanol and 120ml water, add 10g of polyphenolic surface modifier, heat to 80℃, react at 80℃ for 4 hours, after the reaction is completed, cool to room temperature, filter, wash the filter cake with methanol and dry to obtain modified graphene oxide. 2. Dissolve 50g of polyvinyl alcohol in 450ml of deionized water at 90℃ to obtain a 10% polyvinyl alcohol solution. Cool the polyvinyl alcohol solution to 50℃, then add 4g of modified graphene oxide and continue stirring for 2 hours. After the reaction is complete, cool to room temperature, filter, and spray dry the filter cake to obtain a multifunctional oxygen barrier agent.

[0024] The preparation method of the above-mentioned oxygen-barrier superconducting heat-resistant polyethylene pipe is as follows: S1. Mix PE-RT resin, multifunctional oxygen barrier agent, EBS, antioxidant 1010, antioxidant 168 and titanium dioxide evenly to obtain oxygen barrier outer layer compound. S2. Mix PE-RT resin, zinc stearate, aluminum stearate, antioxidant 1010 and antioxidant 168 evenly to obtain hydrophobic inner layer compound. S3. The oxygen-barrier outer layer compound is added to the first extruder for melt extrusion, and the hydrophobic inner layer compound is added to the second extruder for melt extrusion. Then, the mixture is co-extruded through a co-extrusion die and cooled to obtain the oxygen-barrier superconducting heat-resistant polyethylene pipe.

[0025] Example 2 An oxygen-barrier type superconducting heat-resistant polyethylene pipe is made by co-extrusion composite of an oxygen-barrier outer layer and a hydrophobic inner layer. The multifunctional outer layer is made from the following raw materials in parts by weight: 80 parts of PE-RT resin 10 parts of multifunctional oxygen barrier EBS 7 copies Antioxidant 1010 1.2 parts Antioxidant 168 0.8 parts 3 parts titanium dioxide; The hydrophobic inner layer is prepared from the following raw materials in parts by weight: 80 parts of PE-RT resin 3 parts zinc stearate 2 parts aluminum stearate Antioxidant 1010 1.2 parts Antioxidant 168 0.8 parts.

[0026] The preparation method of the oxygen-barrier superconducting heat-resistant polyethylene pipe in this embodiment is the same as that in Example 1.

[0027] Example 3 An oxygen-barrier type superconducting heat-resistant polyethylene pipe is made by co-extrusion composite of an oxygen-barrier outer layer and a hydrophobic inner layer. The multifunctional outer layer is made from the following raw materials in parts by weight: 70 parts of PE-RT resin 7.5 parts of multifunctional oxygen barrier agent EBS 5 copies Antioxidant 1010 0.9 parts Antioxidant 168 0.6 parts 2 parts titanium dioxide; The hydrophobic inner layer is prepared from the following raw materials in parts by weight: 70 parts of PE-RT resin 2 parts zinc stearate 2 parts aluminum stearate Antioxidant 1010 0.9 parts Antioxidant 168 0.6 parts.

[0028] The preparation method of the oxygen-barrier superconducting heat-resistant polyethylene pipe in this embodiment is the same as that in Example 1.

[0029] Comparative Example 1 The difference from Example 3 lies in the use of a multifunctional oxygen barrier agent. The preparation method of the multifunctional oxygen barrier agent in this comparative example is as follows: 1. Disperse 50g of graphene oxide in a mixed solvent of 80ml ethanol and 120ml water, add 10g of maleic anhydride-grafted PE, heat to 80℃, react at 80℃ for 4 hours, after the reaction is completed, cool to room temperature, filter, wash the filter cake with methanol and dry to obtain modified graphene oxide. 2. Dissolve 50g of polyvinyl alcohol in 450ml of deionized water at 90℃ to obtain a 10% polyvinyl alcohol solution. Cool the polyvinyl alcohol solution to 50℃, then add 4g of modified graphene oxide and continue stirring for 2 hours. After the reaction is complete, cool to room temperature, filter, and spray dry the filter cake to obtain a multifunctional oxygen barrier agent.

[0030] Comparative Example 2 The difference from Example 3 lies in the use of a multifunctional oxygen barrier agent. The preparation method of the multifunctional oxygen barrier agent in this comparative example is as follows: 1. Disperse 50g of graphene oxide in a mixed solvent of 80ml ethanol and 120ml water, add 10g SCA-A86T, heat to 80℃, react at 80℃ for 4 hours, after the reaction is completed, cool to room temperature, filter, wash the filter cake with methanol and dry to obtain modified graphene oxide. 2. Dissolve 50g of polyvinyl alcohol in 450ml of deionized water at 90℃ to obtain a 10% polyvinyl alcohol solution. Cool the polyvinyl alcohol solution to 50℃, then add 4g of modified graphene oxide and continue stirring for 2 hours. After the reaction is complete, cool to room temperature, filter, and spray dry the filter cake to obtain a multifunctional oxygen barrier agent.

[0031] Comparative Example 3 The difference from Example 3 is that the hydrophobic inner layer is different; the hydrophobic inner layer of this comparative example does not contain zinc stearate and aluminum stearate.

[0032] The PE-RT pipes prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to the following tests: Mechanical properties: Tested according to the methods in standard GB / T 1040.2-2022. Thermal conductivity: Tested according to the method in standard GB / T42919-2023; Oxygen barrier performance: Tested according to the method in standard GB / T34437-2017.

[0033] The test results are shown in the table below: As shown in the table above, the addition of a special multifunctional oxygen barrier agent in this invention significantly increases the compatibility between polyvinyl alcohol and heat-resistant polyethylene compared to commonly used maleic anhydride grafted compatibilizers and silane coupling agents, thereby significantly improving the oxygen barrier properties and thermal conductivity of heat-resistant polyethylene.

Claims

1. An oxygen-barrier type superconducting heat-resistant polyethylene pipe, characterized in that: It is composed of an oxygen-barrier outer layer and a hydrophobic inner layer, co-extruded composite. The multifunctional outer layer is made from the following raw materials in parts by weight: 60-80 parts of PE-RT resin 5-10 parts of multifunctional oxygen barrier 3-7 parts lubricant 1-2 parts antioxidant 1-3 parts pigment; The multifunctional oxygen barrier is a compatibility-modified polyvinyl alcohol / graphene oxide composite. The hydrophobic inner layer is prepared from the following raw materials in parts by weight: 60-80 parts of PE-RT resin 3-5 parts of stearic acid coordination metal salt 1-2 parts antioxidant.

2. The oxygen-barrier type superconducting heat-resistant polyethylene pipe according to claim 1, characterized in that... The preparation method of the aforementioned multifunctional oxygen inhibitor is as follows: 2.

1. Graphene oxide is dispersed in a mixed solvent of ethanol and deionized water, a polyphenolic surface modifier is added, and the mixture is heated to 70-90℃ and reacted at 70-90℃ for 2-6 hours. After the reaction is completed, the mixture is cooled to room temperature, filtered, and the filter cake is washed with methanol and dried to obtain modified graphene oxide. 2.2 Dissolve polyvinyl alcohol in deionized water at 90-100℃ to obtain a polyvinyl alcohol solution. Cool the polyvinyl alcohol solution to 40-60℃, then add modified graphene oxide, disperse evenly, cool to room temperature, filter, and dry the filter cake to obtain a multifunctional oxygen barrier agent.

3. The oxygen-barrier type superconducting heat-resistant polyethylene pipe according to claim 2, characterized in that... The preparation method of the polyphenol-type surface modifier is as follows: 3.1 Under room temperature and nitrogen protection, the carboxyl functional group of gallic acid and the secondary amine group of SCAA86T silane coupling agent undergo an acylation reaction to generate a siloxane monomer. 3.2 Under nitrogen protection, the tertiary amine group of the siloxane monomer undergoes a quaternization reaction with the chlorine functional group of a chlorinated long-chain alkane with not less than 12 carbon atoms to generate a polyphenolic surface modifier.

4. The oxygen-barrier type superconducting heat-resistant polyethylene pipe according to claim 2, characterized in that: The chlorinated long-chain alkane is selected from at least one of chlorinated hexadecane, chlorinated octadecane, chlorinated tetradecane, and chlorinated dodecane.

5. The oxygen-barrier type superconducting heat-resistant polyethylene pipe according to claim 1, characterized in that: The polyphenol surface modifier is a condensation product of gallic acid and SCA-A86T silane coupling agent.

6. The oxygen-barrier type superconducting heat-resistant polyethylene pipe according to claim 1, characterized in that: The lubricant is selected from at least one of stearamide, calcium stearate, N,N′-ethylene bis-stearamide and polyethylene wax.

7. The oxygen-barrier type superconducting heat-resistant polyethylene pipe according to claim 1, characterized in that: The antioxidant is selected from at least one of antioxidant 1010, antioxidant 168 and antioxidant 1076.

8. The oxygen-barrier type superconducting heat-resistant polyethylene pipe according to claim 1, characterized in that: The pigment is selected from at least one of titanium dioxide, ultramarine, phthalocyanine blue, and phthalocyanine green.

9. The oxygen-barrier type superconducting heat-resistant polyethylene pipe according to claim 1, characterized in that: The stearic acid coordination metal salt is selected from at least one of zinc stearate and aluminum stearate.

10. A method for preparing the oxygen-barrier superconducting heat-resistant polyethylene pipe according to claim 1, characterized in that... Includes the following steps: S1. Mix PE-RT resin, multifunctional oxygen barrier agent, lubricant, antioxidant and pigment evenly to obtain oxygen barrier outer layer compound; S2. Mix PE-RT resin, hydrophobic stearic acid coordination metal salt and antioxidant evenly to obtain hydrophobic inner layer compound; S3. The oxygen-barrier outer layer compound is added to the first extruder for melt extrusion, and the hydrophobic inner layer compound is added to the second extruder for melt extrusion. Then, the mixture is co-extruded through a co-extrusion die and cooled to obtain the oxygen-barrier superconducting heat-resistant polyethylene pipe.

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