A method for preparing multifunctional polyethylene pipe for plastic-lined composite pipe

Abstract

The present invention relates to the technical field of polymer materials, and discloses a method for preparing a multifunctional polyethylene pipe for a plastic-lined composite pipe. The polyethylene pipe comprises the following raw materials: high-density polyethylene, boron nitride reinforcement, composite antibacterial additive, cross-linking agent, antioxidant, and lubricant. High-density polyethylene is used as a matrix material, and by adding the boron nitride reinforcement, the interaction and bonding force with the polyethylene matrix are enhanced, external impact energy is absorbed and dispersed, crack propagation is hindered, and the mechanical properties and toughness of the polyethylene pipe are improved. By adding the composite antibacterial additive, the antibacterial property of the polyethylene pipe is improved. Only a small amount of the composite antibacterial additive is needed to exhibit excellent antibacterial property, effectively preventing bacteria from adhering to the surface of the pipe material to cause corrosion, thereby extending the service life of the polyethylene pipe.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials, and in particular to a method for preparing a multifunctional polyethylene pipe for a plastic-lined composite pipe. Background Art

[0002] The rapid development of industrialization has led to an increasing demand for pipe materials. As a new type of pipe, plastic-lined composite pipe combines the advantages of both metal and plastic. Its composite structure offsets the shortcomings of single materials, improving the overall performance of the pipe and embracing diverse applications. It has gradually become a popular pipe material in the market, widely used in water supply systems, the chemical industry, environmental treatment systems, oil and gas transportation, agricultural irrigation, heating systems, fire protection systems, and marine engineering. Common plastic-lined composite pipes include aluminum alloy and steel-lined composite pipes. Metal pipes serve as the primary support structure of the pipe, with plastic pipes forming the inner or outer wall, or both. Plastic pipes are typically made of materials such as polyvinyl chloride, polypropylene, and polyethylene. Polyethylene has excellent corrosion resistance, ensuring long-term stable operation. When used in water supply systems, it is odorless and non-toxic, without affecting water quality, ensuring water safety and hygiene. Furthermore, polyethylene has a smooth surface and a low friction coefficient, making it less susceptible to scale accumulation. This not only ensures hygiene, but also improves transportation efficiency and reduces energy consumption. Therefore, polyethylene is often used as the plastic pipe material in plastic-lined composite pipes.

[0003] When plastic-lined composite pipes are used in water supply systems, plastic pipes need to withstand internal and external pressures, and stress concentration may cause damage to the pipes. In order to ensure the long-term safe operation of the pipes, the mechanical properties and toughness need to be enhanced, which can effectively avoid pipe deformation and cracking. At the same time, as the part that is in direct contact with domestic water, bacteria can easily attach to the inner wall of the pipe, which has a corrosive effect on the pipe material and will also pollute domestic water. In order to reduce the damage of bacteria to the pipes, plastic pipes need to have antibacterial properties, which can extend the service life of plastic pipes to a certain extent, ensure the safety of water quality, and improve the reliability and stability of the water supply system. Summary of the Invention

[0004] In order to solve the problems mentioned in the background technology, the purpose of the present invention is to provide a method for preparing a multifunctional polyethylene pipe for a plastic-lined composite pipe.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A method for preparing a multifunctional polyethylene pipe for a plastic-lined composite pipe comprises the following steps:

[0007] Step 1: Add 80-100 parts of high-density polyethylene, 4-6 parts of boron nitride reinforcement, 3-5 parts of composite antibacterial additives, 1-3 parts of cross-linking agent, 0.5-1.5 parts of antioxidant, and 1-3 parts of lubricant to a high-speed mixer, set the speed to 500-800 r / min, increase the temperature to 100-140°C, mix and stir for 10-30 minutes, and when the material temperature cools to 30-40°C, discharge the material to obtain a mixed base material;

[0008] Step 2: Add the mixed base material to a twin-screw extruder, set the screw speed of the twin-screw extruder to 30-60 r / min, extrude through the twin-screw extruder, cool and shape, and obtain a polyethylene pipe.

[0009] Furthermore, in step one, the cross-linking agent is diisopropyl peroxide or di-tert-butyl peroxide; the antioxidant is antioxidant 1076 and antioxidant 168 in a mass ratio of 1:1; and the lubricant is any one of polyethylene wax, paraffin wax or zinc stearate.

[0010] Furthermore, in step 2, the temperature of zone 1 of the twin-screw extruder is 160-180°C, the temperature of zone 2 is 170-190°C, the temperature of zone 3 is 180-200°C, the temperature of zone 4 is 200-220°C, and the temperature of zone 5 is 220-230°C.

[0011] Furthermore, the preparation method of the boron nitride reinforcement material comprises the following steps:

[0012] Step A, adding hexagonal boron nitride to a 55%-60% ethanol solution by volume, ultrasonicating for 10-30 minutes, adding the solution to a hydrothermal reactor, reacting at 140-160° C. for 5-8 hours, cooling, centrifuging, precipitating, and vacuum drying to obtain hydroxylated hexagonal boron nitride;

[0013] Step B: adding hydroxylated hexagonal boron nitride to dimethyl sulfoxide, ultrasonicating for 10-30 minutes to form a uniform dispersion, introducing nitrogen, adding isocyanate-terminated polybutadiene and a catalyst to the dispersion, raising the temperature to 85-95° C., keeping the reaction warm for 4-6 hours, filtering, washing the solid product, and vacuum drying to obtain a boron nitride reinforcement.

[0014] Furthermore, in step A, the average particle size of the hexagonal boron nitride is 120 nm.

[0015] Furthermore, in step B, the catalyst is dibutyltin dilaurate or stannous octoate.

[0016] By adopting the above technical solution, during the hydrothermal reaction of hexagonal boron nitride, boiling water accelerates the hydrolysis of hexagonal boron nitride to obtain hydroxylated hexagonal boron nitride. Under the action of the catalyst, the active hydroxyl groups in the hydroxylated hexagonal boron nitride undergo an urethanization reaction with the isocyanate groups in the isocyanate-terminated polybutadiene structure to obtain a boron nitride reinforcement. The boron nitride reinforcement material is organically modified by hexagonal boron nitride and grafted with polybutadiene. This can build a molecular bridge between the interface of hexagonal boron nitride and polyethylene, improve their compatibility, and thus avoid the agglomeration problem of hexagonal boron nitride in the polyethylene matrix. The hexagonal boron nitride is evenly dispersed and orderly arranged in the polyethylene matrix, and the interaction and bonding force between the hexagonal boron nitride and the polyethylene molecular chains are enhanced. When subjected to external force, the polyethylene pipe can bear the load more evenly, effectively disperse and transmit stress, and improve mechanical properties. At the same time, the polybutadiene molecular chain can absorb and disperse external impact energy, hinder crack propagation, reduce the degree of damage to the polyethylene matrix caused by stress concentration, and enhance the toughness of the polyethylene matrix. In addition, under the action of the cross-linking agent, the polybutadiene molecular chain in the boron nitride reinforcement material structure can be cross-linked with the polyethylene matrix polymer chain segment to form a cross-linked network structure, further enhancing the mechanical properties and toughness of the polyethylene matrix, thereby making the polyethylene pipe exhibit higher mechanical properties.

[0017] Furthermore, the preparation method of the composite antibacterial additive is as follows:

[0018] Konjac glucomannan is added to N,N-dimethylformamide, stirred evenly, and then baicalin and a composite catalyst are added. The reaction is carried out at room temperature for 4-6 hours. The product is collected, washed, and dried at 40-50° C. to a constant weight to obtain a composite antibacterial additive.

[0019] By adopting the above technical solution, the large number of active hydroxyl groups in the konjac glucomannan structure can undergo an esterification reaction with the active carboxyl groups in the baicalin structure under the action of a composite catalyst, thereby introducing the natural antibacterial substance baicalin into the konjac glucomannan structure to obtain a composite antibacterial additive. This composite antibacterial additive contains baicalin, a flavonoid antibacterial substance. As a natural antibacterial substance, baicalin has a broad-spectrum antibacterial effect and can impart excellent antibacterial properties to a polyethylene matrix. In addition, konjac glucomannan is an environmentally friendly natural macromolecular organic compound, and after being grafted with baicalin, the precipitation of the small molecule baicalin antibacterial substance can be effectively avoided, resulting in excellent antibacterial properties. By simply adding a small amount of the composite antibacterial additive to the polyethylene matrix, polyethylene pipes can be given a long-lasting antibacterial effect, effectively preventing bacteria from adhering to the surface of the pipe material and corroding the pipe material, thereby extending the service life of the polyethylene pipe.

[0020] Furthermore, the composite catalyst is 4-dimethylaminopyridine and dicyclohexylcarbodiimide in a mass ratio of 2-3:6-8.

[0021] Beneficial effects of the present invention:

[0022] The present invention prepares a boron nitride reinforcement and a composite antibacterial additive and adds them to a polyethylene matrix material, so that the prepared polyethylene pipe has a tensile strength of up to 32.5MPa, a bending elastic modulus of up to 81.8MPa, and an impact strength of up to 26.5KJ / m 2 The antibacterial rate is as high as 99.99%. It has excellent mechanical properties, toughness and antibacterial properties. It can meet the application requirements of polyethylene as a lined plastic composite pipe in the water supply system and has a long service life.

[0023] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0025] Figure 1 This is an infrared spectrum of the boron nitride reinforcement material in an embodiment of the present invention;

[0026] Figure 2 This is an infrared spectrum of konjac glucomannan and a composite antibacterial additive in an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0028] Example 1

[0029] 1. Preparation of Boron Nitride Reinforcement

[0030] Step A, adding 2 g of hexagonal boron nitride with an average particle size of 120 nm to a 55% by volume ethanol solution, ultrasonicating for 20 minutes, adding the solution to a hydrothermal reactor, reacting at 160° C. for 6 hours, cooling, centrifuging, precipitating, and vacuum drying to obtain hydroxylated hexagonal boron nitride;

[0031] Step B: 2 g of hydroxylated hexagonal boron nitride was added to dimethyl sulfoxide, ultrasonicated for 20 min to form a uniform dispersion, nitrogen was introduced, 1.2 g of terminal isocyanate polybutadiene and 0.2 g of dibutyltin dilaurate were added to the dispersion, the temperature was raised to 90 ° C, the reaction was kept warm for 5 h, and the solid product was filtered and washed and vacuum dried to obtain a boron nitride reinforcement.

[0032] The sample was prepared by potassium bromide tablet method, and the infrared test of boron nitride reinforced material was carried out by Fourier infrared spectrometer. Figure 1 As shown, the spectral wavenumber test range is 4000cm -1 -500cm -1 , analysis shows that in the infrared spectrum of boron nitride reinforcement, 3021cm -1 The absorption peak of CH in the double bond appears at 1715 cm -1 The absorption peak of C=O in carbamate appeared at 1536cm -1 The absorption peak of NH appears at 1378 cm -1 The absorption peak of BN appears at 807 cm -1 The absorption peak of BNB appears at

[0033] 2. Preparation of composite antibacterial additives

[0034] 2.5 g of konjac glucomannan was added to N,N-dimethylformamide and stirred evenly. Then, 4.2 g of baicalin, 0.3 g of 4-dimethylaminopyridine and 0.8 g of dicyclohexylcarbodiimide were added and reacted at room temperature for 5 h. The product was collected, washed and dried at 45°C to constant weight to obtain a composite antibacterial additive.

[0035] The potassium bromide tableting method was used to prepare samples, and the konjac glucomannan and the composite antibacterial additives were tested by infrared spectroscopy. Figure 2 As shown, the spectral wavenumber test range is 4000cm -1 -500cm -1 , analysis shows that in the infrared spectrum of konjac glucomannan, 1727cm -1 The absorption peak of C=O in acetyl group appeared at 1065cm -1 The absorption peak of COC appeared at 890 cm -1 The absorption peak of β-1,4 glycosidic bond appeared at 1750cm in the infrared spectrum of the composite antibacterial additive. -1 The area of ​​the C=O absorption peak at 1715 cm -1 The absorption peak of the carbonyl group C=O at position 4 of baicalin appeared at 1608 cm -1 、1571cm -1 、1494cm-1 The absorption peak is that of baicalin skeleton.

[0036] 3. Preparation of polyethylene pipes

[0037] Step 1: Add 80g high-density polyethylene, 4g boron nitride reinforcement, 3g composite antibacterial additive, 1g diisopropyl peroxide, 0.25g antioxidant 1076, 0.25g antioxidant 168, and 1g polyethylene wax into a high-speed mixer, set the speed to 500r / min, increase the temperature to 100°C, mix and stir for 10min, and when the material temperature cools to 30°C, discharge the material to obtain a mixed base material;

[0038] Step 2: Add the mixed base material to a twin-screw extruder, set the screw speed of the twin-screw extruder to 30r / min, the temperature of zone 1 of the twin-screw extruder to 160°C, the temperature of zone 2 to 170°C, the temperature of zone 3 to 180°C, the temperature of zone 4 to 200°C, and the temperature of zone 5 to 220°C. Extrude through the twin-screw extruder, cool and shape, and obtain a polyethylene pipe.

[0039] Example 2

[0040] Preparation of polyethylene pipes

[0041] Step 1: Add 90g of high-density polyethylene, 5g of the boron nitride reinforcement prepared in Example 1, 4g of the composite antibacterial additive prepared in Example 1, 2g of diisophenyl peroxide, 0.5g of antioxidant 1076, 0.5g of antioxidant 168, and 2g of polyethylene wax to a high-speed mixer, set the speed to 650r / min, increase the temperature to 125°C, mix and stir for 20min, and when the material temperature cools to 35°C, discharge the material to obtain a mixed base material;

[0042] Step 2: Add the mixed base material to a twin-screw extruder, set the screw speed of the twin-screw extruder to 45r / min, the temperature of zone 1 of the twin-screw extruder to 170°C, the temperature of zone 2 to 180°C, the temperature of zone 3 to 190°C, the temperature of zone 4 to 210°C, and the temperature of zone 5 to 225°C. Extrude through the twin-screw extruder, cool and shape, and obtain a polyethylene pipe.

[0043] Example 3

[0044] Preparation of polyethylene pipes

[0045] Step 1: Add 100g of high-density polyethylene, 6g of the boron nitride reinforcement prepared in Example 1, 5g of the composite antibacterial additive prepared in Example 1, 3g of diisophenylene peroxide, 0.75g of antioxidant 1076, 0.75g of antioxidant 168, and 3g of polyethylene wax to a high-speed mixer, set the speed to 800r / min, increase the temperature to 140°C, mix and stir for 30min, and when the material temperature cools to 40°C, discharge the material to obtain a mixed base material;

[0046] Step 2: Add the mixed base material to a twin-screw extruder, set the screw speed of the twin-screw extruder to 60r / min, the temperature of zone 1 of the twin-screw extruder to 180°C, the temperature of zone 2 to 190°C, the temperature of zone 3 to 200°C, the temperature of zone 4 to 220°C, and the temperature of zone 5 to 230°C. Extrude through the twin-screw extruder, cool and shape, and obtain a polyethylene pipe.

[0047] Comparative Example 1

[0048] Preparation of polyethylene pipes

[0049] Step 1, 90g high-density polyethylene, 5g boron nitride reinforcement prepared in Example 1, 2g diisophenylene peroxide, 0.5g antioxidant 1076, 0.5g antioxidant 168, and 2g polyethylene wax were added to a high-speed mixer, the speed was set to 650r / min, the temperature was raised to 125°C, and the mixture was stirred for 20min. When the material temperature was cooled to 35°C, the material was discharged to obtain a mixed base material;

[0050] Step 2: Add the mixed base material to a twin-screw extruder, set the screw speed of the twin-screw extruder to 45r / min, the temperature of zone 1 of the twin-screw extruder to 170°C, the temperature of zone 2 to 180°C, the temperature of zone 3 to 190°C, the temperature of zone 4 to 210°C, and the temperature of zone 5 to 225°C. Extrude through the twin-screw extruder, cool and shape, and obtain a polyethylene pipe.

[0051] Comparative Example 2

[0052] Preparation of polyethylene pipes

[0053] Step 1: Add 90g of high-density polyethylene, 4g of the composite antibacterial additive prepared in Example 1, 2g of diisophenyl peroxide, 0.5g of antioxidant 1076, 0.5g of antioxidant 168, and 2g of polyethylene wax to a high-speed mixer, set the speed to 650r / min, increase the temperature to 125°C, mix and stir for 20min, and when the material temperature cools to 35°C, discharge the material to obtain a mixed base material;

[0054] Step 2: Add the mixed base material to a twin-screw extruder, set the screw speed of the twin-screw extruder to 45r / min, the temperature of zone 1 of the twin-screw extruder to 170°C, the temperature of zone 2 to 180°C, the temperature of zone 3 to 190°C, the temperature of zone 4 to 210°C, and the temperature of zone 5 to 225°C. Extrude through the twin-screw extruder, cool and shape, and obtain a polyethylene pipe.

[0055] Comparative Example 3

[0056] Preparation of polyethylene pipes

[0057] Step 1: Add 90g of high-density polyethylene, 5g of hexagonal boron nitride, 4g of the composite antibacterial additive prepared in Example 1, 2g of diisophenyl peroxide, 0.5g of antioxidant 1076, 0.5g of antioxidant 168, and 2g of polyethylene wax to a high-speed mixer, set the speed to 650r / min, increase the temperature to 125°C, mix and stir for 20min, and when the material temperature cools to 35°C, discharge the material to obtain a mixed base material;

[0058] Step 2: Add the mixed base material to a twin-screw extruder, set the screw speed of the twin-screw extruder to 45r / min, the temperature of zone 1 of the twin-screw extruder to 170°C, the temperature of zone 2 to 180°C, the temperature of zone 3 to 190°C, the temperature of zone 4 to 210°C, and the temperature of zone 5 to 225°C. Extrude through the twin-screw extruder, cool and shape, and obtain a polyethylene pipe.

[0059] Comparative Example 4

[0060] Preparation of polyethylene pipes

[0061] Step 1: Add 90g of high-density polyethylene, 5g of the boron nitride reinforcement prepared in Example 1, 4g of baicalin, 2g of diisophenylpropene peroxide, 0.5g of antioxidant 1076, 0.5g of antioxidant 168, and 2g of polyethylene wax to a high-speed mixer, set the speed to 650r / min, increase the temperature to 125°C, mix and stir for 20min, and when the material temperature cools to 35°C, discharge the material to obtain a mixed base material;

[0062] Step 2: Add the mixed base material to a twin-screw extruder, set the screw speed of the twin-screw extruder to 45r / min, set the temperature of zone 1 of the twin-screw extruder to 170°C, the temperature of zone 2 to 180°C, the temperature of zone 3 to 190°C, the temperature of zone 4 to 210°C, and the temperature of zone 5 to 225°C. Extrude through the twin-screw extruder, cool and shape, and obtain a polyethylene pipe.

[0063] Performance testing

[0064] The polyethylene pipes prepared in Examples 1 to 3 and Comparative Examples 1 to 4 were made into specimens that met the test specifications and subjected to performance testing:

[0065] The tensile properties of the specimens were tested according to the standard GB / T 1040.1-2018; the flexural modulus of the specimens was tested according to the standard GB / T 9341-2008; the impact strength of the specimens was tested according to the standard GB / T1843-2008; and the antibacterial properties of the specimens were tested after standing at room temperature for 20 days according to the standard GB / T31402-2023. The results are shown in the following table:

[0066]

[0067] As can be seen from the above table, the polyethylene pipes prepared in Examples 1 to 3 of the present invention have excellent mechanical properties, toughness, and antibacterial properties. Comparative Example 1 did not add a composite antibacterial additive, and the antibacterial performance test results were poor; Comparative Example 2 did not add a boron nitride reinforcement, and the tensile strength, flexural modulus, and impact strength test results were poor; Comparative Example 3 added unmodified hexagonal boron nitride, which has the effect of enhancing mechanical properties, but is prone to agglomeration in the polyethylene matrix, resulting in poor tensile strength test results, and it is impossible to utilize polybutadiene to graft hexagonal boron nitride to enhance the toughness of the polyethylene pipe and cross-link with the polyethylene matrix to further enhance the mechanical properties and toughness, so the tensile strength, flexural modulus, and impact strength test results are poor; Comparative Example 4 added baicalin, but did not graft it with the high-molecular-weight konjac glucomannan. The small molecule baicalin may precipitate in the polyethylene matrix, resulting in reduced antibacterial properties, and therefore the antibacterial rate test result is poor.

[0068] The above content is merely an example and explanation of the concept of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined by the claims, they should all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a multifunctional polyethylene pipe for a plastic-lined composite pipe, characterized in that: The following steps are involved: Step 1: Add 80-100 parts of high-density polyethylene, 4-6 parts of boron nitride reinforcement, 3-5 parts of composite antibacterial additives, 1-3 parts of cross-linking agent, 0.5-1.5 parts of antioxidant, and 1-3 parts of lubricant to a high-pressure mixer, set the speed to 500-800 r / min, increase the temperature to 100-140°C, mix and stir for 10-30 minutes, and discharge the material when the material temperature cools to 30-40°C to obtain a mixed base material; Step 2: Add the mixed base material to a twin-screw extruder, set the screw speed of the twin-screw extruder to 30-60 r / min, extrude through the twin-screw extruder, cool and shape, and obtain a polyethylene pipe; In step 1, the cross-linking agent is dicumyl peroxide or di-tert-butyl peroxide; the antioxidant is antioxidant 1076 and antioxidant 168 in a mass ratio of 1:1; the lubricant is any one of polyethylene wax, paraffin wax or zinc stearate; In step 2, the temperature of the twin-screw extruder zone 1 is 160-180°C, the temperature of the zone 2 is 170-190°C, the temperature of the zone 3 is 180-200°C, the temperature of the zone 4 is 200-220°C, and the temperature of the zone 5 is 220-230°C; The preparation method of the boron nitride reinforcement material comprises the following steps: step A, adding hexagonal boron nitride to an ethanol solution with a volume fraction of 55%-60%, ultrasonically treating the solution for 10-30 minutes, adding the solution to a hydrothermal reactor, reacting the solution at a temperature of 140-160° C. for 5-8 hours, cooling, centrifuging, precipitating, and vacuum drying to obtain hydroxylated hexagonal boron nitride; step B, adding the hydroxylated hexagonal boron nitride to dimethyl sulfoxide, ultrasonically treating the solution for 10-30 minutes to form a uniform dispersion, introducing nitrogen, adding isocyanate-terminated polybutadiene and a catalyst to the dispersion, raising the temperature to 85-95° C., maintaining the reaction temperature for 4-6 hours, filtering the solution, washing the solid product, and vacuum drying the solution to obtain the boron nitride reinforcement material; In step A, the average particle size of the hexagonal boron nitride is 120 nm; In step B, the catalyst is dibutyltin dilaurate or stannous octoate.

2. The method for preparing a multifunctional polyethylene pipe for a plastic-lined composite pipe according to claim 1, characterized in that: The preparation method of the composite antibacterial additive is as follows: konjac glucomannan is added to N,N-dimethylformamide, stirred evenly, baicalin and a composite catalyst are added, reacted at room temperature for 4-6 hours, the product is collected, washed, and dried at 40-50°C to constant weight to obtain a composite antibacterial additive.

3. The method for preparing a multifunctional polyethylene pipe for a plastic-lined composite pipe according to claim 2, characterized in that: The composite catalyst is 4-dimethylaminopyridine and dicyclohexylcarbodiimide in a mass ratio of 2-3:6-8.

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