A high-strength steel-plastic composite pipe and its preparation method

Abstract

The present invention relates to the field of pipe technology, and in particular to a high-strength steel-plastic composite pipe and a preparation method thereof. The high-strength steel-plastic composite pipe provided by the present invention is composed of a plastic inner pipe, a steel outer pipe, and a bonding layer between the plastic inner pipe and the steel outer pipe; the plastic inner pipe includes the following raw materials in parts by weight: 100 parts of high-density polyethylene, 1-5 parts of tributyl phosphite, 1-5 parts of paraffin wax, 3-8 parts of di-n-octyltin bisthioglycolate, and 5-10 parts of modified silica. The plastic inner pipe provided by the present invention can improve the heat resistance of the inner pipe while improving the hardness of the plastic inner pipe, so that the steel-plastic composite pipe prepared by the present invention can have both hardness and heat resistance, while also having high strength.

Description

Technical Field

[0001] The present invention relates to the technical field of pipes, and in particular to a high-strength steel-plastic composite pipe and a preparation method thereof. Background Art

[0002] Plastic pipes, with their advantages of light weight, high strength, low cost, and corrosion resistance, have gradually become the primary pipe material used in urban construction, water network construction, and other fields. However, plastic pipes lack sufficient hardness. Steel-plastic composite pipes, an emerging composite pipe material, offer excellent corrosion resistance and high hardness, making them widely used in oil and natural gas transportation, industrial and mining pipes, drinking water pipes, and drainage pipes.

[0003] Existing steel-plastic composite pipes are mostly composed of a plastic inner tube, an adhesive layer, and a steel tube. Although they have excellent performance, the heat resistance and surface hardness of the plastic inner tube still cannot meet the requirements of many specific working environments. Therefore, it is necessary to develop a new plastic inner tube with excellent heat resistance and surface hardness, so that the resulting steel-plastic composite pipe can meet working scenarios with high heat resistance and hardness requirements. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defect that the plastic inner tube in the existing high-density polyethylene steel-plastic composite pipe cannot have both good heat resistance and surface hardness, and further provide a high-strength steel-plastic composite pipe and a preparation method thereof.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A high-strength steel-plastic composite pipe, comprising a plastic inner pipe, a steel outer pipe, and a bonding layer between the plastic inner pipe and the steel outer pipe; the plastic inner pipe comprises the following raw materials in parts by weight: 100 parts of high-density polyethylene, 1-5 parts of tributyl phosphite, 1-5 parts of paraffin wax, 3-8 parts of di-n-octyltin bis(thioglycolate), and 5-10 parts of modified silica.

[0007] Preferably, the preparation method of the modified silicon dioxide comprises the following steps:

[0008] 1) mixing ethanol, bamboo charcoal, a silane coupling agent, and water, and then performing ultrasonication to obtain a mixed solution;

[0009] 2) adding silicon dioxide and low-density polyethylene to the mixed solution, and then performing ultrasonic treatment. After the ultrasonic treatment, stirring the mixed solution, filtering the solution, and drying the filter cake to obtain the modified silicon dioxide.

[0010] Preferably, the mass ratio of silicon dioxide, low-density polyethylene, ethanol, bamboo charcoal, silane coupling agent and water is 1: (0.4-0.5): (0.3-0.5): (0.7-1.0): (0.4-0.8): (7-10).

[0011] Preferably, the ultrasonic power in step 1) is 400-600W, and the ultrasonic time is 1-5h.

[0012] Preferably, the ultrasonic power in step 2) is 400-600W, and the ultrasonic time is 1-5h.

[0013] Preferably, the stirring temperature in step 2) is 60-80° C., and the stirring time is 2-4 h.

[0014] Preferably, the silane coupling agent is KH550.

[0015] The present invention also provides a method for preparing the high-strength steel-plastic composite pipe described above, comprising the following steps:

[0016] 1) mixing high-density polyethylene, tributyl phosphite, paraffin, di-n-octyltin bis(2-ethylhexylthioglycolate), and modified silicon dioxide, heating and melting the mixture, then mixing and granulating the molten mixture, and finally extruding the granulated particles to obtain a plastic inner tube;

[0017] 2) The outer surface of the plastic inner tube and the inner surface of the steel tube are coated with adhesive respectively, and then the plastic inner tube is inserted into the steel tube, and the interior of the plastic inner tube is pressurized to obtain the composite tube.

[0018] Preferably, the heating and melting temperature is 200-210° C., and the heating and melting time is 0.5-2 h.

[0019] Preferably, the adhesive is an epoxy resin adhesive; the pressurizing pressure is 0.6-0.7 MPa, and the pressurizing time is 0.5-1 h.

[0020] Beneficial effects of the present invention:

[0021] 1) The present invention provides a high-strength steel-plastic composite pipe, comprising a plastic inner pipe, a steel outer pipe, and a bonding layer therebetween; the plastic inner pipe comprises the following raw materials in parts by weight: 100 parts high-density polyethylene, 1-5 parts tributyl phosphite, 1-5 parts paraffin wax, 3-8 parts di-n-octyltin bisthioglycolate, and 5-10 parts modified silica. By adding modified silica to the raw materials for the plastic inner pipe, the modified silica interacts with the other raw materials to improve both the hardness and heat resistance of the plastic inner pipe, resulting in a steel-plastic composite pipe having both hardness and heat resistance while also exhibiting high strength.

[0022] 2) The steel-plastic composite pipe provided by the present invention further comprises a method for preparing the modified silica, comprising the following steps: mixing ethanol, bamboo charcoal, a silane coupling agent, and water, followed by sonication to obtain a mixed solution; adding silica and low-density polyethylene to the mixed solution, followed by sonication, stirring the mixed solution after the sonication, filtering, and drying the filter cake to obtain the modified silica. The present invention utilizes bamboo charcoal and low-density polyethylene to modify silica. The resulting modified silica interacts with the other raw materials to significantly enhance the hardness and heat resistance of the plastic inner pipe. DETAILED DESCRIPTION

[0023] The following examples are provided for a better understanding of the present invention and are not intended to limit the best mode of implementation. They do not limit the content and scope of protection of the present invention. Any product identical or similar to the present invention obtained by anyone under the guidance of the present invention or by combining the features of the present invention with other prior arts shall fall within the scope of protection of the present invention.

[0024] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in this field can be used. If the manufacturer of the reagents or instruments is not specified, they are all commercially available conventional reagents.

[0025] Example 1

[0026] This embodiment provides a plastic inner tube, which includes the following materials:

[0027] High-density polyethylene 10kg Tributyl phosphite 0.4kg paraffin 0.5kg 2-Ethylhexyl bis(thioglycolate)dioctyltin 0.7kg Modified silica 0.5kg

[0028] The preparation method of the modified silicon dioxide comprises the following steps:

[0029] 1) 0.5 kg of ethanol, 0.8 kg of bamboo charcoal, 0.6 kg of KH550, and 10 kg of water were mixed, and then ultrasonicated at an ultrasonic power of 500 W for 4 h to obtain a mixed solution;

[0030] 2) adding 1 kg of silica and 0.4 kg of low-density polyethylene to the mixed solution, and then ultrasonicating the solution at an ultrasonic power of 500 W for 4 hours. After the ultrasonication, the mixed solution was stirred at 70° C. for 3 hours. After the stirring, the solution was filtered and the filter cake was dried to obtain the modified silica.

[0031] This embodiment also provides a high-strength steel-plastic composite pipe, which is composed of the aforementioned plastic inner pipe, a steel outer pipe, and a bonding layer between the plastic inner pipe and the steel outer pipe. The preparation method of the composite pipe includes the following steps:

[0032] 1) mixing high-density polyethylene, tributyl phosphite, paraffin, di-n-octyltin bis(thioglycolate), and modified silica, heating and melting the mixture at a temperature of 210° C. for 1 hour, and then granulating the molten mixture. Finally, the granulated particles are extruded to obtain a plastic inner tube;

[0033] 2) The outer surface of the plastic inner tube and the inner surface of the steel tube are coated with epoxy resin adhesive respectively, and then the plastic inner tube is inserted into the steel tube, and the interior of the plastic inner tube is pressurized at a pressure of 0.6 MPa for 0.5 h to obtain the composite tube.

[0034] Example 2

[0035] This embodiment provides a plastic inner tube, which includes the following materials:

[0036]

[0037]

[0038] The preparation method of the modified silicon dioxide comprises the following steps:

[0039] 1) 0.5 kg of ethanol, 0.8 kg of bamboo charcoal, 0.6 kg of KH550, and 10 kg of water were mixed, and then ultrasonicated at an ultrasonic power of 500 W for 4 h to obtain a mixed solution;

[0040] 2) adding 1 kg of silica and 0.4 kg of low-density polyethylene to the mixed solution, and then ultrasonicating the solution at an ultrasonic power of 500 W for 4 hours. After the ultrasonication, the mixed solution was stirred at 70° C. for 3 hours. After the stirring, the solution was filtered and the filter cake was dried to obtain the modified silica.

[0041] This embodiment also provides a high-strength steel-plastic composite pipe, which is composed of the aforementioned plastic inner pipe, a steel outer pipe, and a bonding layer between the plastic inner pipe and the steel outer pipe. The preparation method of the composite pipe includes the following steps:

[0042] 1) mixing high-density polyethylene, tributyl phosphite, paraffin, di-n-octyltin bis(thioglycolate), and modified silica, heating and melting the mixture at a temperature of 210° C. for 1 hour, and then granulating the molten mixture. Finally, the granulated particles are extruded to obtain a plastic inner tube;

[0043] 2) The outer surface of the plastic inner tube and the inner surface of the steel tube are coated with epoxy resin adhesive respectively, and then the plastic inner tube is inserted into the steel tube, and the interior of the plastic inner tube is pressurized at a pressure of 0.6 MPa for 0.5 h to obtain the composite tube.

[0044] Example 3

[0045] This embodiment provides a plastic inner tube, which includes the following materials:

[0046] High-density polyethylene 10kg Tributyl phosphite 0.4kg paraffin 0.5kg 2-Ethylhexyl bis(thioglycolate)dioctyltin 0.7kg Modified silica 1.0kg

[0047] The preparation method of the modified silicon dioxide comprises the following steps:

[0048] 1) 0.5 kg of ethanol, 0.8 kg of bamboo charcoal, 0.6 kg of KH550, and 10 kg of water were mixed, and then ultrasonicated at an ultrasonic power of 500 W for 4 h to obtain a mixed solution;

[0049] 2) adding 1 kg of silica and 0.4 kg of low-density polyethylene to the mixed solution, and then ultrasonicating the solution at an ultrasonic power of 500 W for 4 hours. After the ultrasonication, the mixed solution was stirred at 70° C. for 3 hours. After the stirring, the solution was filtered and the filter cake was dried to obtain the modified silica.

[0050] This embodiment also provides a high-strength steel-plastic composite pipe, which is composed of the aforementioned plastic inner pipe, a steel outer pipe, and a bonding layer between the plastic inner pipe and the steel outer pipe. The preparation method of the composite pipe includes the following steps:

[0051] 1) mixing high-density polyethylene, tributyl phosphite, paraffin, di-n-octyltin bis(thioglycolate), and modified silica, heating and melting the mixture at a temperature of 210° C. for 1 hour, and then granulating the molten mixture. Finally, the granulated particles are extruded to obtain a plastic inner tube;

[0052] 2) The outer surface of the plastic inner tube and the inner surface of the steel tube are coated with epoxy resin adhesive respectively, and then the plastic inner tube is inserted into the steel tube, and the interior of the plastic inner tube is pressurized at a pressure of 0.6 MPa for 0.5 h to obtain the composite tube.

[0053] Comparative Example 1

[0054] This comparative example provides a plastic inner tube. The difference between the plastic inner tube and Example 1 is that the modified silicon dioxide is replaced by silicon dioxide.

[0055] Comparative Example 2

[0056] This comparative example provides a plastic inner tube. The difference between the plastic inner tube and Example 1 is that bamboo charcoal is not added in the preparation method of the modified silica.

[0057] Test Case

[0058] The properties of the plastic inner tubes prepared in the above examples and comparative examples were tested. The test methods used for the performance test data are as follows: flexural strength was measured according to GB / T 9341-2008; thermal expansion coefficient was measured according to GB / T 36800.2-2018; and Shore hardness was measured according to GB / T 2411-2008. The test results are shown in Table 1.

[0059] Table 1 Performance test results

[0060]

[0061] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A high-strength steel-plastic composite pipe, characterized in that: The composite pipe is composed of a plastic inner pipe, a steel outer pipe, and a bonding layer between the plastic inner pipe and the steel outer pipe; the plastic inner pipe comprises the following raw materials in parts by weight: 100 parts of high-density polyethylene, 1-5 parts of tributyl phosphite, 1-5 parts of paraffin wax, 3-8 parts of di-n-octyltin bisthioglycolate, and 5-10 parts of modified silica; The preparation method of the modified silicon dioxide comprises the following steps: 1) mixing ethanol, bamboo charcoal, silane coupling agent and water, and then ultrasonicating to obtain a mixed solution; 2) adding silica and low-density polyethylene to the mixed solution, and then performing ultrasonic treatment. After the ultrasonic treatment, stirring the mixed solution, filtering the solution, and drying the filter cake to obtain the modified silica; The mass ratio of silica, low-density polyethylene, ethanol, bamboo charcoal, silane coupling agent and water is 1: (0.4-0.5): (0.3-0.5): (0.7-1.0): (0.4-0.8): (7-10).

2. The high-strength steel-plastic composite pipe according to claim 1, characterized in that: In step 1), the ultrasonic power is 400-600W, and the ultrasonic time is 1-5h.

3. The high-strength steel-plastic composite pipe according to claim 1, characterized in that: In step 2), the ultrasonic power is 400-600W, and the ultrasonic time is 1-5h.

4. The high-strength steel-plastic composite pipe according to claim 1, characterized in that: The stirring temperature in step 2) is 60-80°C, and the stirring time is 2-4 hours.

5. The high-strength steel-plastic composite pipe according to claim 1, characterized in that: The silane coupling agent is KH550.

6. The method for preparing the high-strength steel-plastic composite pipe according to any one of claims 1 to 5, characterized in that: The steps include: 1) High-density polyethylene, tributyl phosphite, paraffin, di-n-octyltin bis(2-ethylhexylthioglycolate), and modified silica are mixed and heated to melt, and the melted mixture is then mixed and granulated, and the granulated particles are finally extruded to obtain a plastic inner tube; 2) The outer surface of the plastic inner tube and the inner surface of the steel tube are coated with adhesive respectively, and then the plastic inner tube is inserted into the steel tube, and the interior of the plastic inner tube is pressurized to obtain the composite tube.

7. The method for preparing a high-strength steel-plastic composite pipe according to claim 6, characterized in that: The heating and melting temperature is 200-210° C., and the heating and melting time is 0.5-2 hours.

8. The method for preparing a high-strength steel-plastic composite pipe according to claim 6 or 7, characterized in that: The adhesive is an epoxy resin adhesive; the pressurizing pressure is 0.6-0.7 MPa, and the pressurizing time is 0.5-1 h.

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