MPP pipe with lasting high-temperature resistance and preparation method of MPP pipe

Abstract

The invention relates to the technical field of MPP pipes, in particular to a durable high-temperature-resistant MPP pipe and a preparation method thereof.The durable high-temperature-resistant MPP pipe is prepared from, by weight, 90-110 parts of polypropylene, 12-17 parts of surface modified boron nitride, 8-12 parts of a toughening agent, 1-5 parts of an auxiliary toughening agent, 0.6-1.4 parts of a nucleating agent, 1-3 parts of a dispersing agent and 0.5-1.5 parts of an antioxidant; the surface modified boron nitride is prepared by reacting boron nitride with a silane coupling agent; the nucleating agent is a mixture of polyacrylamide, alkyl glycoside and a WBG-II nucleating agent; the method has the advantage of improving the high-temperature resistance of the polypropylene pipe.

Description

Technical Field

[0001] The present application relates to the technical field of MPP pipes, and in particular to a durable, high-temperature resistant MPP pipe and a preparation method thereof. Background Art

[0002] Plastics are used in various industries due to their excellent properties, convenient molding process, and relatively low cost. Among them, MPP pipes, or polypropylene pipes, are considered a new type of green building energy-saving material due to their advantages such as light weight, non-toxicity, heat resistance, corrosion resistance, long service life, and recyclability. They are widely used in building water supply systems, heating systems, gas transmission systems, chemical fluid transportation systems, water treatment systems, etc. Polypropylene pipes have the advantages of good heat resistance and low thermal conductivity. Hot water pipes made from them have significant insulation and energy-saving effects. However, for higher temperature environments, such as transporting high-temperature mud, current polypropylene pipes are prone to damage due to prolonged high temperature, which limits their application. Summary of the Invention

[0003] In order to improve the high temperature resistance of polypropylene pipes, the present application provides a durable and high temperature resistant MPP pipe and a preparation method thereof.

[0004] In the first aspect, the present application provides a durable, high-temperature resistant MPP pipe, which adopts the following technical solutions: A durable, high-temperature resistant MPP pipe comprises the following raw materials in parts by weight: 90-110 parts of polypropylene, 12-17 parts of surface-modified boron nitride, 8-12 parts of a toughening agent, 1-5 parts of an auxiliary toughening agent, 0.6-1.4 parts of a nucleating agent, 1-3 parts of a dispersant, and 0.5-1.5 parts of an antioxidant; the surface-modified boron nitride is prepared by reacting boron nitride with a silane coupling agent; and the nucleating agent is a mixture of polyacrylamide, alkyl glycoside, and a WBG-II nucleating agent.

[0005] By adopting the above technical solution, the present application mainly uses polyacrylamide, alkyl glycoside, and WBG-Ⅱ nucleating agent for compounding as a nucleating agent, wherein the molecular structure of polyacrylamide contains a large number of amide groups, and its molecular skeleton is a polypropylene chain. The polypropylene skeleton can improve the compatibility between polyacrylamide and the polypropylene pipe system, thereby making it uniformly dispersed in the system. At the same time, the amide groups it contains enable it to act as a heterogeneous nucleating agent for the polymer, provide a large number of nucleation sites, reduce the crystallization activation energy, accelerate the crystallization process of polypropylene, and form finer α-crystal spherulites. In addition, the long chain characteristics of the polymer nucleating agent can reduce the generation of cracks in the system; alkyl glycoside assists in dispersing the polypropylene chain segments through hydrogen bonds and hydrophobic interactions, inhibits excessive grain growth, and further refines the crystal size; WBG-Ⅱ (rare earth β nucleating agent): rare earth ions (such as La 3+) forms weak coordination bonds with PP segments, inducing the formation of β-crystals. The β-cells are small and evenly distributed, and their hexagonal structure offers greater thermal stability than the α-crystal (monoclinic). The three raw materials in the compound nucleating agent work synergistically to simultaneously regulate the ratio of α- and β-crystals. The α-crystal provides rigidity, while the β-crystal enhances toughness. This combined improvement in dimensional stability at high temperatures contributes to the excellent high-temperature resistance of the polypropylene pipe.

[0006] Preferably, in the nucleating agent, the mass ratio of polyacrylamide, alkyl glycoside and WBG-Ⅱ nucleating agent is (3-7):(1-3):10.

[0007] By adopting the above technical solution, the ratio of polyacrylamide, alkyl glycoside and WBG-Ⅱ nucleating agent is further limited so that their synergistic effect can be optimized.

[0008] Preferably, the average molecular weight of the polyacrylamide is in the range of 6 million to 10 million.

[0009] By adopting the above technical solution, the average molecular weight of polyacrylamide in this range can fully exert its advantages as a polymer nucleating agent and be fully dispersed in the polypropylene pipe. When its molecular weight is higher, due to its own viscosity and polarity, it is not conducive to its dispersion, affecting its effect.

[0010] Preferably, the alkyl glycoside is one or more of APG0810, APG1214, APG0816, APG1216 and APG1218.

[0011] By adopting the above technical solution, when alkyl glycoside is selected within this range, technical effects similar to those in the embodiments of the present application can be obtained. Although the embodiments of the present application have not been explored one by one, based on the principles thereof, they are all within the protection scope of the present application.

[0012] Preferably, the molecular structure of the silane coupling agent does not contain amino, epoxy, hydroxyl and carboxyl groups.

[0013] By adopting the above technical solution, the silane coupling agent is hydrolyzed in the ethanol / water system to generate silanol (-Si-OH), which combines with the hydroxyl group or oxygen vacancy on the surface of the boron nitride to form a stable interface layer. The molecular structure of the silane coupling agent does not contain polar groups such as amino, epoxy, hydroxyl and carboxyl groups, which can make the interface between the surface of the boron nitride and the polypropylene pipe system more compatible, make the boron nitride more dispersible, and enable the boron nitride to play a role in improving the strength of the polypropylene pipe.

[0014] Preferably, the average particle size of the boron nitride is in the range of 800-1200 mesh.

[0015] By adopting the above technical solution, boron nitride with this particle size can play its role in improving the strength of polypropylene pipes and is also conducive to its uniform dispersion in the system.

[0016] Preferably, the auxiliary toughening agent is dihydroxyl-terminated polyether modified silicone oil.

[0017] By employing this technical solution, the silicone oil molecular chain maintains its flexibility even at high temperatures. By sacrificing its own deformation to absorb energy, it mitigates crack propagation in the polypropylene matrix caused by thermal expansion or external forces, and also mitigates the rigidity tendencies associated with boron nitride. The double-terminated hydroxyl structure forms a physical entanglement with the polypropylene chain segments, enhancing interfacial interactions and preventing brittle fracture at high temperatures. The low viscosity of silicone oil reduces melt flow resistance, improves the dispersibility of fillers like boron nitride, and avoids processing difficulties associated with high filler content.

[0018] Preferably, the dispersant is poloxamer.

[0019] By employing this technical solution, poloxamer (an amphiphilic block copolymer) adsorbs at the interface between boron nitride and PP, creating a steric hindrance effect that prevents filler aggregation. During high-temperature processing (such as twin-screw extrusion), the poloxamer's melt viscosity adapts to the polypropylene matrix, maintaining uniform dispersion. The uniformly dispersed boron nitride and nucleating agent synergistically enhance the material's tensile strength and flexural modulus while avoiding brittleness caused by localized filler concentration.

[0020] In a second aspect, the present application provides a method for preparing a durable, high-temperature resistant MPP pipe, which adopts the following technical solution: A method for preparing a durable, high-temperature-resistant MPP pipe comprises the following steps: S1. Dispersing a silane coupling agent in an ethanol / water solution with a mass fraction of 3-5% to obtain a silane coupling agent solution; dispersing 0.8-1.2 g of boron nitride in 80-120 ml of the silane coupling agent solution, heating to 65-80° C., stirring and reacting for 8-20 hours, filtering, washing, and drying to obtain surface-modified boron nitride; S2. Mix the raw materials in proportion and then transfer them to a twin-screw extruder. The temperature settings of the twin-screw extruder from the first temperature zone to the ninth temperature zone of the die head are as follows: 170-195°C, 180-195°C, 195-205°C, 210-225°C, 225-235°C, 235-245°C, 235-245°C, 215-225°C, 215-225°C, and the temperature of the die head is 230-245°C. After extrusion by the twin-screw extruder, the extruder is naturally cooled for 0.2-1h, and then water-cooled and granulated to obtain a durable and high-temperature resistant MPP pipe.

[0021] By adopting the above technical solution, by gradually increasing the temperature, it is possible to promote PP melting and activation of the nucleating agent, induce the initial formation of the α crystal form, and then promote the growth of the β crystal form through the high temperature zone. At the same time, the boron nitride is evenly dispersed to form a stable crystal nucleus; segmented temperature control avoids local overheating, reduces PP oxidation degradation and nucleating agent decomposition, and ensures the long-term high-temperature performance stability of the material; after extrusion, through natural cooling, on the one hand, the cooling rate is controlled to avoid excessive crystallization leading to internal stress concentration; on the other hand, it can prevent the temperature from cooling too quickly, resulting in a large temperature difference between the surface and the interior of the base material, resulting in more fillers such as boron nitride precipitating to the surface, making its texture uneven and affecting the quality of the material.

[0022] In summary, this application includes at least one of the following beneficial technical effects: 1. This application mainly uses polyacrylamide, alkyl glycoside, and WBG-Ⅱ nucleating agent for compounding as a nucleating agent. Among them, the molecular structure of polyacrylamide contains a large number of amide groups, and its molecular skeleton is a polypropylene chain. The polypropylene skeleton can improve the compatibility between polyacrylamide and the polypropylene pipe system, thereby making it uniformly dispersed in the system. At the same time, the amide groups it contains enable it to act as a heterogeneous nucleating agent for polymers, provide a large number of nucleation sites, reduce crystallization activation energy, accelerate the crystallization process of polypropylene, and form finer α-crystal spherulites. In addition, the long chain characteristics of the polymer nucleating agent can reduce the generation of cracks in the system; alkyl glycoside assists in dispersing polypropylene segments through hydrogen bonds and hydrophobic interactions, inhibits excessive grain growth, and further refines the crystal size; WBG-Ⅱ (rare earth β nucleating agent): rare earth ions (such as La 3+ ) forms weak coordination bonds with PP segments, inducing the formation of β-crystals. The β-cells are small and evenly distributed, and their hexagonal structure offers greater thermal stability than the α-crystal (monoclinic). The three raw materials in the compound nucleating agent work synergistically to simultaneously regulate the ratio of α- and β-crystals. The α-crystal provides rigidity, while the β-crystal enhances toughness. This combined improvement in dimensional stability at high temperatures contributes to the excellent high-temperature resistance of the polypropylene pipe.

[0023] 2. The polypropylene pipes prepared in this application have excellent high temperature resistance, with tensile strength between 21.7-22.4MPa, bending strength between 27.4-28.7MPa, and simply supported beam notched impact strength between 37-41KJ / m 2 At the same time, after being placed at a temperature of 150°C for 2 months, the tensile strength retention rate was 92.7-95.7%, the bending strength retention rate was 92.6-95.5%, and the simply supported beam notched impact strength retention rate was 92.3-95.4%. DETAILED DESCRIPTION

[0024] The following is a further detailed description of this application in conjunction with the specific content.

[0025] raw material The raw materials used in the examples of the present application are all commercially available products, among which polypropylene was purchased from Dimin Plastic Raw Materials Department, Changping, Dongguan City, with the brand name PP H5416; the auxiliary toughening agent is double-terminated hydroxyl polyether modified silicone oil, model BY16-201, brand Dow Corning; the dispersant is poloxamer, model F68; polyacrylamide was purchased from Henan Cerrick Biotechnology Co., Ltd.; the WBG-Ⅱ nucleating agent was purchased from Guangdong Weilinna New Materials Technology Co., Ltd.; the toughening agent is PP toughening agent, purchased from Dongguan Shanyi Plastic Co., Ltd.; the model of the antioxidant is antioxidant 1010. Example

[0026] Example 1 A durable, high-temperature resistant MPP pipe, the raw materials and amounts of which are shown in Table 1, and the preparation method thereof is as follows: S1. Dispersing methyltrimethoxysilane in an ethanol / water solution with a volume ratio of 1:1, where the mass fraction of methyltrimethoxysilane is 4%, to obtain a silane coupling agent solution; dispersing 1 g of boron nitride with a particle size of 800 mesh in 100 ml of the methyltrimethoxysilane solution, heating to 70° C., stirring and reacting for 10 hours, filtering, washing, and drying to obtain surface-modified boron nitride; S2. The raw materials were mixed by a mixer according to the proportions in Table 1, and then transferred to a twin-screw extruder from the main feeding port. The temperature settings of the twin-screw extruder from the first temperature zone to the ninth temperature zone of the die head were as follows: 180°C, 190°C, 200°C, 220°C, 230°C, 240°C, 240°C, 220°C, and 220°C. The temperature of the die head was 240°C. After extrusion by the twin-screw extruder, the mixture was naturally cooled for 0.5h, and then water-cooled at 30°C and granulated to obtain a durable and high-temperature resistant MPP pipe.

[0027] Among them, the nucleating agent is a mixture of polyacrylamide, alkyl glycoside and WBG-Ⅱ nucleating agent, and the mass ratio of polyacrylamide, alkyl glycoside and WBG-Ⅱ nucleating agent is 5:2:10; polyacrylamide is cationic and its average molecular weight is 8 million; the model of alkyl glycoside is APG1214.

[0028] Table 1 Raw materials and amounts of raw materials used in Example 1 (kg) Example 2 A durable, high-temperature resistant MPP pipe is different from Example 1 in that the average molecular weight of its polyacrylamide is 6 million, and the remaining steps are the same as Example 1.

[0029] Example 3 A durable, high-temperature resistant MPP pipe is different from Example 1 in that the average molecular weight of its polyacrylamide is 10 million, and the remaining steps are the same as Example 1.

[0030] Example 4 A durable, high-temperature resistant MPP pipe is different from Example 1 in that the amount of nucleating agent added is 0.6 kg, and the remaining steps are the same as Example 1.

[0031] Example 5 A durable, high-temperature resistant MPP pipe is different from Example 1 in that the amount of nucleating agent added is 1.4 kg, and the remaining steps are the same as Example 1.

[0032] Comparative Example Comparative Example 1 A durable, high-temperature resistant MPP pipe is different from Example 1 in that polyacrylamide is not added as a nucleating agent, and the remaining steps are the same as Example 1.

[0033] Comparative Example 2 A durable, high-temperature resistant MPP pipe is different from Example 1 in that no alkyl glycoside is added to its nucleating agent, and the remaining steps are the same as Example 1.

[0034] Comparative Example 3 A durable, high-temperature resistant MPP pipe is different from Example 1 in that WBG-Ⅱ nucleating agent is not added to the nucleating agent, and the remaining steps are the same as Example 1.

[0035] Comparative Example 4 A durable, high-temperature resistant MPP pipe is different from Example 1 in that its surface-modified boron nitride is replaced by an equal mass of surface-unmodified boron nitride, and the remaining steps are the same as Example 1.

[0036] Performance testing Detection method / test method MPP pipes were prepared according to the preparation methods of Examples 1-5 and Comparative Examples 1-4, and then tested according to the following test methods. The test results are shown in Tables 2 and 3.

[0037] Tensile strength: tested according to the test method in ISO 527-2; Bending strength: tested according to the test method in ISO 178; Charpy notched impact strength: tested according to the test method in ISO 179.

[0038] Aging conditions: The samples of each embodiment were placed at a temperature of 150° C. for 2 months, and then the tensile strength, flexural strength and simply supported beam notch strength were tested, and the retention rates of the tensile strength, flexural strength and simply supported beam notch strength were calculated respectively.

[0039] Table 2 Test results of Examples 1-5 and Comparative Examples 1-4 Table 3 High temperature resistance test results of Examples 1-5 and Comparative Examples 1-4 The test data in Table 2 and Table 3 show that the polypropylene pipes prepared in this application have excellent high temperature resistance, with tensile strength between 21.7-22.4 MPa, bending strength between 27.4-28.7 MPa, and simply supported beam notched impact strength between 37-41 KJ / m 2 At the same time, after being placed at a temperature of 150°C for 2 months, the tensile strength retention rate was 92.7-95.7%, the bending strength retention rate was 92.6-95.5%, and the simply supported beam notched impact strength retention rate was 92.3-95.4%.

[0040] The present application mainly uses polyacrylamide, alkyl glycoside, and WBG-Ⅱ nucleating agent for compounding as a nucleating agent, wherein the molecular structure of polyacrylamide contains a large number of amide groups, and its molecular skeleton is a polypropylene chain. The polypropylene skeleton can improve the compatibility between polyacrylamide and the polypropylene pipe system, thereby making it uniformly dispersed in the system. At the same time, the amide groups it contains enable it to act as a heterogeneous nucleating agent for the polymer, provide a large number of nucleation sites, reduce the crystallization activation energy, accelerate the crystallization process of polypropylene, and form finer α-crystal spherulites. In addition, the long chain characteristics of the polymer nucleating agent can reduce the generation of cracks in the system; alkyl glycoside assists in dispersing the polypropylene chain segments through hydrogen bonds and hydrophobic interactions, inhibits excessive grain growth, and further refines the crystal size; WBG-Ⅱ (rare earth β nucleating agent): rare earth ions (such as La 3+ ) forms weak coordination bonds with the PP segments, inducing the formation of a β-crystal structure. The β-cells are small and uniformly distributed, and their hexagonal structure exhibits greater thermal stability than the α-crystal (monoclinic). The three raw materials in the composite nucleating agent work synergistically to simultaneously regulate the ratio of α- and β-crystals. The α-crystal provides rigidity, while the β-crystal enhances toughness. This combined improvement in dimensional stability at high temperatures results in excellent high-temperature resistance for the polypropylene pipe. This is demonstrated by the test data from Example 1 and Comparative Examples 1-3.

[0041] When the average molecular weight of polyacrylamide is between 6 million and 10 million, it can fully demonstrate its advantages as a polymer nucleating agent and fully disperse within the polypropylene pipe. Higher molecular weights, due to its inherent viscosity and polarity, hinder its dispersion, thus affecting its effectiveness. For more details, please refer to the test data of Examples 1-3. Based on this, and in conjunction with Examples 4-5, an optimal addition amount of 1 kg of nucleating agent is found.

[0042] In the ethanol / water system, the silane coupling agent hydrolyzes to form silanols (-Si-OH), which bind to hydroxyl groups or oxygen vacancies on the surface of the boron nitride, forming a stable interface layer. This enhances the interfacial compatibility between the boron nitride surface and the polypropylene pipe system, improving the dispersibility of the boron nitride and enabling the boron nitride to enhance the strength of the polypropylene pipe. For more details, please refer to the experimental data of Example 1 and Comparative Example 4.

[0043] This specific embodiment is merely an explanation of the present invention and is not intended to limit the present invention. After reading this specification, those skilled in the art may make non-creative modifications to this embodiment as needed. However, as long as such modifications are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. A durable, high-temperature-resistant MPP pipe, characterized by: The invention comprises the following raw materials in parts by weight: 90-110 parts of polypropylene, 12-17 parts of surface-modified boron nitride, 8-12 parts of a toughening agent, 1-5 parts of an auxiliary toughening agent, 0.6-1.4 parts of a nucleating agent, 1-3 parts of a dispersant and 0.5-1.5 parts of an antioxidant; the surface-modified boron nitride is prepared by reacting boron nitride with a silane coupling agent; and the nucleating agent is a mixture of polyacrylamide, alkyl glycoside and a WBG-II nucleating agent.

2. The durable, high-temperature resistant MPP pipe according to claim 1, characterized in that: In the nucleating agent, the mass ratio of polyacrylamide, alkyl glycoside and WBG-Ⅱ nucleating agent is (3-7): (1-3):

10.

3. The durable, high-temperature-resistant MPP pipe according to claim 2, characterized in that: The average molecular weight of the polyacrylamide is in the range of 6 million to 10 million.

4. The durable, high-temperature-resistant MPP pipe according to claim 2, characterized in that: The alkyl glycoside is one or more of APG0810, APG1214, APG0816, APG1216 and APG1218.

5. The durable, high-temperature-resistant MPP pipe according to claim 1, characterized in that: The molecular structure of the silane coupling agent does not contain amino, epoxy, hydroxyl and carboxyl groups.

6. The durable, high-temperature-resistant MPP pipe according to claim 1, characterized in that: The average particle size of the boron nitride is in the range of 800-1200 meshes.

7. The durable, high-temperature-resistant MPP pipe according to claim 1, characterized in that: The auxiliary toughening agent is double-terminated hydroxyl polyether modified silicone oil.

8. The durable, high-temperature-resistant MPP pipe according to claim 1, characterized in that: The dispersant is poloxamer.

9. A method for preparing the durable, high-temperature-resistant MPP pipe according to any one of claims 1 to 8, characterized in that: It includes the following steps: S1. Dispersing a silane coupling agent in an ethanol / water solution with a mass fraction of 3-5% to obtain a silane coupling agent solution; dispersing 0.8-1.2 g of boron nitride in 80-120 ml of the silane coupling agent solution, heating to 65-80° C., stirring and reacting for 8-20 hours, filtering, washing, and drying to obtain surface-modified boron nitride; S2. Mix the raw materials in proportion and then transfer them to a twin-screw extruder. The temperature settings of the twin-screw extruder from the first temperature zone to the ninth temperature zone of the die head are as follows: 170-195°C, 180-195°C, 195-205°C, 210-225°C, 225-235°C, 235-245°C, 235-245°C, 215-225°C, 215-225°C, and the temperature of the die head is 230-245°C. After extrusion by the twin-screw extruder, the extruder is naturally cooled for 0.2-1h, and then water-cooled and granulated to obtain a durable and high-temperature resistant MPP pipe.

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