MPP pipe with enhanced tensile strength and method for manufacturing the same

Abstract

The present application relates to the technical field of MPP pipe, especially to a kind of MPP pipe of enhanced tensile strength and preparation method thereof, the MPP pipe of enhanced tensile strength, including the following weight parts of raw materials: 80-99 parts of polypropylene, 10-25 parts of composite elastomer, 20-42 parts of polypropylene fiber, 2-5 parts of heat stabilizer, 1-2 parts of antioxidant, 1-4 parts of lubricant and 0.5-1 parts of coupling agent.The purpose is to optimize the formula of MPP pipe, and the performance of fiber reinforced MPP pipe, so that MPP pipe has good mechanical properties, especially tensile strength and other properties, so that MPP pipe has wider range of use.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of MPP pipe, in particular to a MPP pipe with enhanced tensile strength and a preparation method thereof. BACKGROUND

[0002] MPP pipe, i.e. modified polypropylene pipe, is a special pipe material with excellent performance. Its unique performance, such as excellent electrical insulation, high temperature resistance, corrosion resistance, wear resistance and aging resistance, makes MPP pipe widely used in many fields, such as power system, municipal engineering, communication industry, non-excavation construction, transportation system and the like.

[0003] In some fields such as transportation system and non-excavation construction, when using MPP pipe, it is required not only to have electrical insulation, high temperature resistance, corrosion resistance and aging resistance, but also to have good flexibility, pressure resistance and impact resistance. At present, the MPP pipe on the market is generally above 15 MPa, and some standards require that the tensile strength at (23±2) ℃ should be greater than 24.0 MPa, and the tensile strength at 70 ℃ is also maintained at about 18.0 MPa, and the bending strength at (23±2) ℃ is not less than 37.0 MPa. The long-term use temperature range of MPP pipe is generally between -5 ℃ and 70 ℃, although it can be suitable for various weather conditions, but in some construction fields such as subway, highway, tunnel, bridge and non-excavation, the requirements for tensile strength, bending strength, flexibility and the like of MPP pipe are higher, and some MPP pipe manufacturers actively explore in these aspects, but it is still necessary to explore in order to provide more possibilities. SUMMARY

[0004] Therefore, the purpose of the present application is to provide a MPP pipe with enhanced tensile strength and a preparation method thereof, by optimizing the formula of the MPP pipe and using fiber to enhance the performance of the MPP pipe, so that the MPP pipe has good mechanical properties, especially tensile strength and the like, thereby making the MPP pipe have a wider range of use.

[0005] The present application solves the above technical problems by the following technical means:

[0006] A MPP pipe with enhanced tensile strength comprises the following raw materials by weight: 80-99 parts of polypropylene, 10-25 parts of composite elastomer, 20-42 parts of polypropylene fiber, 2-5 parts of heat stabilizer, 1-2 parts of antioxidant, 1-4 parts of lubricant and 0.5-1 part of coupling agent.

[0007] According to the above technical means, by adding the composite elastomer and polypropylene fibers in the polypropylene, the mechanical properties of the polypropylene can be effectively enhanced, especially the tensile strength, bending strength, flexibility and other properties, and the prepared MPP pipe can be suitable for various environments and has a wide range of applications. By adding additives, the performance of the MPP pipe can be further enhanced.

[0008] Preferably, the polypropylene comprises copolymerized polypropylene and grafted polypropylene, the melt index of the copolymerized polypropylene is 1.5-2.8 g / 10 min, and the grafted polypropylene is at least one of ethylene grafted polypropylene, styrene grafted polypropylene and methyl methacrylate grafted polypropylene.

[0009] Further preferably, the addition ratio of the copolymerized polypropylene and the grafted polypropylene is 10: (1-2.5).

[0010] Further preferably, the grafted polypropylene is styrene grafted polypropylene, and the grafting rate is 2-3%.

[0011] According to the above technical means, by using the mixture of copolymerized polypropylene and grafted polypropylene, the tensile strength, impact strength and adhesion strength of the product can be improved, and by controlling the addition ratio and grafting rate, the tensile strength and impact strength of the product can be further improved, and the processing performance can be effectively improved.

[0012] Preferably, the composite elastomer comprises ethylene-propylene-diene rubber, silicone oil, nanofiber and ethylene-vinyl acetate copolymer.

[0013] Further preferably, the nanofiber is at least one of carbon nanofiber, polypropylene nanofiber and ceramic nanofiber.

[0014] Further preferably, the silicone oil is methyl silicone oil.

[0015] According to the above technical means, by using ethylene-propylene-diene rubber, silicone oil, nanofiber and ethylene-vinyl acetate copolymer to form the composite elastomer, on the one hand, the mechanical properties of the ethylene-propylene-diene rubber can be enhanced through the mutual cooperation of these raw materials, and on the other hand, a three-dimensional network structure can be formed in the ethylene-propylene-diene rubber through the cooperation of the silicone oil, nanofiber and ethylene-vinyl acetate copolymer, and through the dispersion and crosslinking effect of the methyl silicone oil, better compatibility and crosslinking network can be formed when mixed with polypropylene, so that the ethylene-propylene-diene rubber can be more uniformly distributed to enhance the performance of the polypropylene.

[0016] Preferably, the preparation of the composite elastomer comprises the following steps:

[0017] Put the ethylene-propylene-diene rubber and ethylene-vinyl acetate copolymer into a mixing device, stir for 5-10 min at 120-140℃, then add the silicone oil and nanofiber, continue to stir for 10-30 min, transfer into an extruder, extrude and granulate to obtain the composite elastomer.

[0018] According to the above technical means, by first melting and mixing the ethylene-propylene-diene rubber and ethylene-vinyl acetate copolymer, then adding the nanofiber and silicone oil, the nanofiber can be fully dispersed in the melt mixture and crosslinked, and under the action of the ethylene-vinyl acetate copolymer, a crosslinked three-dimensional network structure is formed.

[0019] As preferred, the polypropylene fiber includes at least one of polypropylene staple fiber, polypropylene long fiber, and polypropylene chip fiber.

[0020] Further preferably, the polypropylene fiber is polypropylene staple fiber.

[0021] Further preferably, the polypropylene staple fiber is mineral-filled polypropylene staple fiber.

[0022] By using mineral-filled polypropylene staple fiber, not only the dimensional stability of the polypropylene fiber can be improved, but also the temperature resistance can be improved, thereby facilitating the preparation of the polypropylene staple fiber in the polypropylene pipe.

[0023] Further preferably, the mineral in the mineral-filled polypropylene staple fiber is one or a combination of talc, calcium carbonate, silica, and glass fiber.

[0024] Further preferably, the mineral is talc.

[0025] By adding talc-filled polypropylene staple fiber, not only the impact resistance and flexibility of the pipe can be enhanced, but also the heat resistance of the pipe can be increased, and during the addition process, the polypropylene staple fiber can be well compatible with the polypropylene, achieving better results while reducing the use of additives, thereby saving costs.

[0026] As preferred, the heat stabilizer is one or a combination of barium salt heat stabilizer, cadmium salt heat stabilizer, calcium salt heat stabilizer, stearate salt heat stabilizer, organic tin heat stabilizer, and auxiliary heat stabilizer.

[0027] Further preferably, the heat stabilizer is calcium-zinc composite stabilizer.

[0028] As preferred, the antioxidant is at least one of antioxidant 1076, antioxidant 1010, antioxidant 264, antioxidant CA, and antioxidant DNP.

[0029] Further preferably, the antioxidant is antioxidant 264.

[0030] Preferably, the lubricant is at least one of oxidized polyethylene wax, fatty acid amide, polyethylene wax, polyurethane lubricant, oleic acid amide.

[0031] Further preferably, the lubricant is a mixture of oxidized polyethylene wax and oleic acid amide, and the addition ratio of the oxidized polyethylene wax and the oleic acid amide is 1:1.

[0032] Preferably, the coupling agent is at least one of a silane coupling agent, a titanate coupling agent, and an aluminate coupling agent.

[0033] Further preferably, the coupling agent is a silane coupling agent.

[0034] The application also discloses a method for preparing the MPP pipe with enhanced tensile strength, which uses the raw material described above and comprises the following steps:

[0035] S1. Put the polypropylene into a mixer, stir for 5-10 min at 110-130℃, add the heat stabilizer and the antioxidant, continue to stir for 5-10 min, then add the composite elastomer, the polypropylene fiber, the lubricant, and the coupling agent, heat to 160-180℃, and stir for 3-6 min to obtain the mixture;

[0036] S2. Put the mixture treated in the step S1 into a double-screw extruder, and perform shaping through a spray vacuum shaping box after extrusion by the double-screw extruder to obtain the MPP pipe;

[0037] S3. Perform heat treatment on the MPP pipe in the step S2 to obtain the MPP pipe with enhanced tensile performance.

[0038] According to the above technical means, the subsequent treatment of heat treatment after the preparation of the MPP pipe can further enhance the tensile performance of the pipe.

[0039] Preferably, in the step S3, the MPP pipe is placed in a drying tunnel and baked at 35-42℃ during the heat treatment, and the rotation speed of the MPP pipe is 10-20 r / min and the residence time is 30-50 s during the baking process.

[0040] According to the above technical means, by controlling the temperature, the rotation speed, and the baking time of the MPP pipe in the drying tunnel, the tensile performance of the MPP pipe can be improved without affecting the performance of the MPP pipe.

[0041] The application using the above scheme has the following advantages:

[0042] 1. By adding composite elastomer and polypropylene fiber in polypropylene, the mechanical properties of polypropylene can be effectively enhanced, especially the tensile strength, bending strength, flexibility and other properties, and the prepared MPP pipe can be suitable for various environments and has wide application range, and by adding additives, the performance of the MPP pipe can be further enhanced;

[0043] 2. In the composite elastomer, by using ethylene-propylene-diene rubber, silicone oil, nanofiber and ethylene-vinyl acetate copolymer, on the one hand, the mechanical properties of the ethylene-propylene-diene rubber can be enhanced through the mutual cooperation of these raw materials, and on the other hand, a three-dimensional network structure can be formed in the ethylene-propylene-diene rubber through the cooperation of the silicone oil, nanofiber and ethylene-vinyl acetate copolymer, so that better compatibility and crosslinking network can be formed when mixed with polypropylene, and the performance of polypropylene can be improved;

[0044] 3. In the present application, the tensile properties of the pipe material can be further enhanced through subsequent heat treatment process after the preparation of the MPP pipe. BRIEF DESCRIPTION OF DRAWINGS

[0045] The present application can be further illustrated by the non-limiting examples shown in the accompanying drawings;

[0046] Figure 1 is a structural schematic diagram of the MPP pipe for enhancing tensile strength in the embodiments of the present application;

[0047] Among them, 1, MPP pipe. DETAILED DESCRIPTION

[0048] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application:

[0049] Example 1, preparation method of MPP pipe for enhancing tensile strength

[0050] In this embodiment, the raw materials used are as follows: copolymerized polypropylene with a melt index of 1.5-2.8 g / 10 min; grafted polypropylene with a grafting rate of 2-3%; the addition ratio of copolymerized polypropylene and grafted polypropylene is 10:1. Ethylene-propylene-diene rubber, methyl silicone oil, polypropylene nanofiber, ethylene-vinyl acetate copolymer; talc filled polypropylene short fiber; calcium-zinc composite stabilizer; antioxidant 264; oxidized polyethylene wax and oleic acid amide; silane coupling agent.

[0051] Preparation of composite elastomer

[0052] 100 parts by weight of ethylene-propylene-diene rubber and 56 parts by weight of ethylene-vinyl acetate copolymer were placed in a mixing device, stirred at 135℃ for 10 min, then 5 parts by weight of methyl silicone oil and 34 parts by weight of polypropylene nanofiber were added, and stirring was continued for 20 min, and then the mixture was transferred into an extruder and extruded and pelletized at a die head temperature of 185-190℃ to obtain a composite elastomer.

[0053] Preparation of MPP pipe with enhanced tensile strength

[0054] S1. 90 parts by weight of copolymerized polypropylene and 9 parts by weight of grafted polypropylene were placed in a mixer, stirred at 120℃ for 10 min, then 4.5 parts by weight of calcium-zinc composite stabilizer and 2 parts by weight of antioxidant 264 were added, and stirring was continued for 8 min, then 18 parts by weight of composite elastomer, 20 parts by weight of talc-filled polypropylene short fiber, 1.2 parts by weight of oxidized polyethylene wax, 1.2 parts by weight of oleic acid amide, and 0.8 parts by weight of silane coupling agent were added, and the temperature was raised to 175℃, and stirring was continued for 5 min to obtain a mixture;

[0055] S2. The mixture treated in step S1 was transferred into a twin-screw extruder, and after extrusion by the twin-screw extruder, the process parameters of the twin-screw extruder were as follows: zone 1 was 200-220℃, zone 2 was 190-200℃, zone 3 was 180-195℃, zone 4 was 170-185℃, zone 5 was 165-175℃, and the die head temperature was 180℃-190℃, and then the MPP pipe was shaped by a spray vacuum shaping box, the water cooling temperature of the spray vacuum shaping box was 17±1℃, and the pulling speed was 2.5 m / min to obtain the MPP pipe.

[0056] S3. The MPP pipe in step S2 was heat treated, and during the heat treatment, the MPP pipe was placed in a drying channel and baked at 42℃, and during the baking process, the rotation speed of the MPP pipe was 20 r / min, and the residence time was 40 s to obtain the MPP pipe 1 with enhanced tensile properties.

[0057] Example 2, preparation method two of MPP pipe with enhanced tensile strength

[0058] In the embodiments of the present application, the same raw materials as in Example 1 were used, and the difference was that the addition ratio of copolymerized polypropylene and grafted polypropylene was 10:2.

[0059] Preparation of composite elastomer

[0060] Put 100 parts by weight of ethylene-propylene-diene rubber and 56 parts by weight of ethylene-vinyl acetate copolymer into a mixing device, stir for 10 min at 135℃, then add 5 parts by weight of methyl silicone oil and 34 parts by weight of polypropylene nanofiber, continue to stir for 20 min, transfer into an extruder, extrude and pelletize at a die head temperature of 185-190℃, to obtain a composite elastomer.

[0061] Preparation of MPP pipe with enhanced tensile strength

[0062] S1. Put 77.5 parts by weight of copolymerized polypropylene and 15.5 parts by weight of grafted polypropylene into a mixer, stir for 10 min at 120℃, add 3.6 parts by weight of calcium-zinc composite stabilizer and 1.2 parts by weight of antioxidant 264, continue to stir for 8 min, then add 22 parts by weight of composite elastomer, 26 parts by weight of talc-filled polypropylene short fiber, 1.6 parts by weight of oxidized polyethylene wax, 1.6 parts by weight of oleic acid amide, and 1 part by weight of silane coupling agent, heat to 175℃, and stir for 5 min to obtain a mixture;

[0063] S2. Transfer the mixture treated in step S1 into a twin-screw extruder, and after extrusion by the twin-screw extruder, the process parameters of the twin-screw extruder are as follows: 200-220℃ for zone 1, 190-200℃ for zone 2, 180-195℃ for zone 3, 170-185℃ for zone 4, 165-175℃ for zone 5, and the die head temperature is 180℃-190℃, then perform shaping by a spray vacuum shaping box, the water cooling temperature of the spray vacuum shaping box is 17±1℃, and the pulling speed is 2.5 m / min, to obtain an MPP pipe;

[0064] S3. Perform heat treatment on the MPP pipe in step S2, and during the heat treatment, place the MPP pipe in a drying channel and bake at 42℃, the rotation speed of the MPP pipe during the baking process is 20 r / min, and the residence time is 40 s, to obtain an MPP pipe 1 with enhanced tensile properties.

[0065] Example 3, preparation method three of MPP pipe with enhanced tensile strength

[0066] In this example, the raw materials used are the same as in Example 1, and the difference is that the addition ratio of copolymerized polypropylene and grafted polypropylene is 10:2.5.

[0067] Preparation of composite elastomer

[0068] Put 100 parts by weight of ethylene-propylene-diene rubber and 56 parts by weight of ethylene-vinyl acetate copolymer into a mixing device, stir for 10 min at 135℃, then add 5 parts by weight of methyl silicone oil and 34 parts by weight of polypropylene nanofiber, continue to stir for 20 min, transfer into an extruder, extrude and pelletize at a die head temperature of 185-190℃, to obtain a composite elastomer.

[0069] Preparation of MPP pipe with enhanced tensile strength

[0070] S1. Put 64 parts by weight of copolymerized polypropylene and 16 parts by weight of branched polypropylene into a mixer, stir for 10 min at 120℃, add 2 parts by weight of calcium-zinc composite stabilizer and 1 part by weight of antioxidant 264, continue to stir for 6 min, then add 25 parts by weight of composite elastomer, 42 parts by weight of talc-filled polypropylene short fiber, 1.8 parts by weight of oxidized polyethylene wax, 1.8 parts by weight of oleic acid amide, and 1 part by weight of silane coupling agent, heat to 175℃, and stir for 6 min to obtain a mixture;

[0071] S2. Transfer the mixture treated in step S1 into a twin-screw extruder, and after extrusion by the twin-screw extruder, the process parameters of the twin-screw extruder are as follows: zone 1 is 200-220℃, zone 2 is 190-200℃, zone 3 is 180-195℃, zone 4 is 170-185℃, zone 5 is 165-175℃, and the die head temperature is 180℃-190℃. The MPP pipe is shaped by a spray vacuum shaping box, the water cooling temperature of the spray vacuum shaping box is 17±1℃, and the pulling speed is 2.5 m / min, to obtain the MPP pipe;

[0072] S3. Heat treat the MPP pipe in step S2, and during the heat treatment, the MPP pipe is placed in a drying channel and baked at 42℃, the rotation speed of the MPP pipe during the baking process is 20 r / min, and the residence time is 40 s, to obtain the MPP pipe 1 with enhanced tensile properties.

[0073] Example 4, method four for preparing MPP pipe

[0074] In this example, the same raw materials as in Example 2 are used, except that the raw materials of the composite elastomer are directly added without pre-preparation, as follows:

[0075] S1. 77.5 parts by weight of the copolymerized polypropylene and 15.5 parts by weight of the grafted polypropylene were placed in a mixer, stirred at 120℃ for 10 min, 3.6 parts by weight of calcium-zinc composite stabilizer and 1.2 parts by weight of antioxidant 264 were added, and stirring was continued for 8 min. Then 11 parts by weight of the ternary ethylene-propylene rubber, 1 part by weight of methyl silicone oil, 5 parts by weight of polypropylene nanofiber, 5 parts by weight of ethylene-vinyl acetate copolymer, 26 parts by weight of talcum powder filled polypropylene short fiber, 1.6 parts by weight of oxidized polyethylene wax, 1.6 parts by weight of oleic acid amide and 1 part by weight of silane coupling agent were added, and the temperature was raised to 175℃, and stirring was continued for 5 min to obtain a mixture;

[0076] S2. The mixture treated in step S1 was transferred into a double screw extruder. After extrusion by the double screw extruder, the process parameters of the double screw extruder were as follows: 200-220℃ for the first zone, 190-200℃ for the second zone, 180-195℃ for the third zone, 170-185℃ for the fourth zone, 165-175℃ for the fifth zone, and 180℃-190℃ for the die head temperature. The MPP pipe was obtained by shaping through a spray vacuum shaping box, with a water cooling temperature of the spray vacuum shaping box being 17±1℃ and a pulling speed being 2.5 m / min.

[0077] S3. The MPP pipe in step S2 was subjected to heat treatment. During the heat treatment, the MPP pipe was placed in a baking channel and baked at 42℃. During the baking process, the rotation speed of the MPP pipe was 20 r / min, and the residence time was 40 s. The MPP pipe 1 with enhanced tensile properties was obtained.

[0078] Example 5, Preparation method five of MPP pipe

[0079] In this example, the same raw materials as in Example 2 were used, except that no composite elastomer was added. The specific process was as follows:

[0080] S1. 77.5 parts by weight of the copolymerized polypropylene and 15.5 parts by weight of the grafted polypropylene were placed in a mixer, stirred at 120℃ for 10 min, 3.6 parts by weight of calcium-zinc composite stabilizer and 1.2 parts by weight of antioxidant 264 were added, and stirring was continued for 8 min. Then 26 parts by weight of talcum powder filled polypropylene short fiber, 1.6 parts by weight of oxidized polyethylene wax, 1.6 parts by weight of oleic acid amide and 1 part by weight of silane coupling agent were added, and the temperature was raised to 175℃, and stirring was continued for 5 min to obtain a mixture;

[0081] S2. The mixture treated in S1 step is transferred into a twin-screw extruder, after extruded by the twin-screw extruder, the process parameters of the twin-screw extruder are: 200-220℃ for the first zone, 190-200℃ for the second zone, 180-195℃ for the third zone, 170-185℃ for the fourth zone, 165-175℃ for the fifth zone, the temperature of the die head is 180℃-190℃, and the MPP pipe is obtained by shaping through a spray vacuum shaping box, the water cooling temperature of the spray vacuum shaping box is 17±1℃, the pulling speed is 2.5m / min;

[0082] S3. The MPP pipe in S2 step is heat treated, the MPP pipe is placed in a baking tunnel and baked at 42℃, during the baking process, the rotating speed of the MPP pipe is 20r / min, and the residence time is 40s, and the MPP pipe 1 with enhanced tensile properties is obtained.

[0083] Example 6, preparation method six of MPP pipe

[0084] In this embodiment, the raw materials used are the same as in Example 2, except that no composite elastomer is added, but instead, ethylene-propylene-diene rubber is added, as follows:

[0085] S1. 77.5 parts by weight of copolymerized polypropylene and 15.5 parts by weight of grafted polypropylene are placed in a mixer, stirred at 120℃ for 10min, 3.6 parts by weight of calcium-zinc composite stabilizer and 1.2 parts by weight of antioxidant 264 are added, and stirring is continued for 8min, then 22 parts by weight of ethylene-propylene-diene rubber, 26 parts by weight of talcum powder filled polypropylene short fiber, 1.6 parts by weight of oxidized polyethylene wax, 1.6 parts by weight of oleic acid amide and 1 part by weight of silane coupling agent are added, the temperature is raised to 175℃, and stirring is carried out for 5min to obtain a mixture;

[0086] S2. The mixture treated in S1 step is transferred into a twin-screw extruder, after extruded by the twin-screw extruder, the process parameters of the twin-screw extruder are: 200-220℃ for the first zone, 190-200℃ for the second zone, 180-195℃ for the third zone, 170-185℃ for the fourth zone, 165-175℃ for the fifth zone, the temperature of the die head is 180℃-190℃, and the MPP pipe is obtained by shaping through a spray vacuum shaping box, the water cooling temperature of the spray vacuum shaping box is 17±1℃, the pulling speed is 2.5m / min;

[0087] S3. The MPP pipe in S2 step is heat treated, the MPP pipe is placed in a baking tunnel and baked at 42℃, during the baking process, the rotating speed of the MPP pipe is 20r / min, and the residence time is 40s, and the MPP pipe 1 with enhanced tensile properties is obtained.

[0088] Example 7, Preparation method seven of MPP pipe

[0089] In this example, the raw materials used are the same as in Example 2, except that no composite elastomer is added, but polypropylene nanofiber is added, the use amount of polypropylene nanofiber is 22 parts by weight, and the remaining steps are the same as in Example 6.

[0090] Example 8, Preparation method eight of MPP pipe

[0091] In this example, the raw materials used are the same as in Example 2, except that no composite elastomer is added, but ethylene-vinyl acetate copolymer is added, the use amount of ethylene-vinyl acetate copolymer is 22 parts by weight, and the remaining steps are the same as in Example 6.

[0092] Example 9, Preparation method nine of MPP pipe

[0093] In this example, the raw materials used are the same as in Example 2, except that no composite elastomer is added, but ethylene-vinyl acetate copolymer is added, the use amount of ethylene-vinyl acetate copolymer is 22 parts by weight, and the remaining steps are the same as in Example 6.

[0094] Example 10, Preparation method ten of MPP pipe

[0095] In this example, the raw materials used are the same as in Example 2, except that no composite elastomer is added, but ethylene-vinyl acetate copolymer is added, the use amount of ethylene-vinyl acetate copolymer is 22 parts by weight, and the remaining steps are the same as in Example 6.

[0096] Example 11, Preparation method eleven of MPP pipe

[0097] In this example, the raw materials used are the same as in Example 2, except that no composite elastomer is added, but ethylene-vinyl acetate copolymer is added, the use amount of ethylene-vinyl acetate copolymer is 22 parts by weight, and the remaining steps are the same as in Example 6.

[0098] Example 12, Preparation method twelve of MPP pipe

[0099] In this example, the raw materials used are the same as in Example 2, except that no composite elastomer and talcum powder filled polypropylene short fiber are added, as follows:

[0100] S1. Put 77.5 parts by weight of copolymerized polypropylene and 15.5 parts by weight of grafted polypropylene into a mixer, stir at 120℃ for 10 min, add 3.6 parts by weight of calcium-zinc composite stabilizer and 1.2 parts by weight of antioxidant 264, continue to stir for 8 min, then add 1.6 parts by weight of oxidized polyethylene wax, 1.6 parts by weight of oleic acid amide and 1 part by weight of silane coupling agent, heat to 175℃, stir for 5 min, to obtain a mixture;

[0101] S2. Transfer the mixture treated in S1 step into a twin-screw extruder, after extrusion by the twin-screw extruder, the process parameters of the twin-screw extruder are: 200-220℃ for the first zone, 190-200℃ for the second zone, 180-195℃ for the third zone, 170-185℃ for the fourth zone, 165-175℃ for the fifth zone, and the die temperature is 180℃-190℃, shape by a spray vacuum shaping box, the water cooling temperature of the spray vacuum shaping box is 17±1℃, the pulling speed is 2.5 m / min, to obtain the MPP pipe;

[0102] S3. Heat treat the MPP pipe in S2 step, when heat treating, place the MPP pipe in a baking channel, bake at 42℃, during the baking process, the rotation speed of the MPP pipe is 20 r / min, and the residence time is 40 s, to obtain the MPP pipe 1 with enhanced tensile properties.

[0103] Example 13, preparation method thirteen of MPP pipe

[0104] In this example, the same raw materials as in Example 2 are used, except that the MPP pipe is not heat treated, as follows:

[0105] S1. Put 77.5 parts by weight of copolymerized polypropylene and 15.5 parts by weight of grafted polypropylene into a mixer, stir at 120℃ for 10 min, add 3.6 parts by weight of calcium-zinc composite stabilizer and 1.2 parts by weight of antioxidant 264, continue to stir for 8 min, then add 22 parts by weight of composite elastomer, 26 parts by weight of talc filled polypropylene short fiber, 1.6 parts by weight of oxidized polyethylene wax, 1.6 parts by weight of oleic acid amide and 1 part by weight of silane coupling agent, heat to 175℃, stir for 5 min, to obtain a mixture;

[0106] S2. The mixture treated in S1 is transferred into a twin-screw extruder. After extrusion, the process parameters of the twin-screw extruder are as follows: 200-220℃ for the first zone, 190-200℃ for the second zone, 180-195℃ for the third zone, 170-185℃ for the fourth zone, 165-175℃ for the fifth zone, and 180℃-190℃ for the head temperature. The MPP pipe is obtained by shaping through a spray vacuum shaping box, with a water cooling temperature of 17±1℃ of the spray vacuum shaping box and a pulling speed of 2.5m / min.

[0107] The MPP pipes prepared in Examples 1-3 are subjected to performance tests, including tensile strength, bending strength, notched impact strength, and ring stiffness tests. The tensile strength is tested according to the national standard GB / T 1040-92, the notched impact strength is tested by a simply supported beam impact strength test, and the ring stiffness is tested according to the national standard DL / T 802.1. The test results are shown in Table 1.

[0108]

[0109] According to the data in Table 1, the MPP pipes prepared in Examples 1-3 have good tensile strength, bending strength, notched impact strength, and ring stiffness. The tensile strength at 23℃ is about 2 times higher than that of conventional MPP pipes, i.e., about 33.8% higher than the standard, especially for Example 2, which is about 35% higher. The tensile strength at 70℃ is about 34.8% higher than the standard, especially for Example 2, which is about 35.5% higher. Therefore, the raw materials and preparation method used in the present application can significantly improve the tensile strength of the MPP pipes.

[0110] The bending strength is about 17.8% higher than the standard, and the bending strength of Example 2 is about 18.3% higher. Therefore, the bending strength is also significantly improved. The simply supported beam impact strength is about 29.3% higher than the standard, and the ring stiffness SN40 is about 16.7% higher than the standard. This indicates that the raw materials and preparation method used in the present application can not only improve the ring stiffness of the MPP pipes, but also improve the tensile strength.

[0111] The MPP pipes prepared in Examples 4-13 are subjected to the same performance tests as described above, and the test results are shown in Table 2.

[0112]

[0113] According to the data in Table 2, when the raw materials of the composite elastomer are directly added in the MPP pipe, the tensile strength, bending strength and notched impact strength of the MPP pipe are obviously reduced, but the ring stiffness is not obviously reduced, which shows that the pre-preparation of the composite elastomer can improve the tensile strength, bending strength and notched impact strength of the MPP pipe to a certain extent. When the composite elastomer is not added in the MPP pipe, the tensile strength, bending strength, notched impact strength and ring stiffness of the MPP pipe are obviously reduced, which shows that the addition of the composite elastomer can improve the tensile strength, bending strength, notched impact strength and ring stiffness of the MPP pipe.

[0114] According to the data in Table 2, when only one raw material or two raw materials of the composite elastomer are added in the MPP pipe, the tensile strength, bending strength, notched impact strength and ring stiffness of the MPP pipe are greatly reduced. When the ethylene-vinyl acetate copolymer is added alone, the tensile performance and bending performance of the MPP pipe are improved more obviously. When the polypropylene nanofiber is added alone, the performance of the MPP pipe is improved more obviously in the simply supported beam impact strength, but the ring stiffness of the three is similar.

[0115] Compared with adding any two of the three raw materials of the ethylene-vinyl acetate copolymer, the polypropylene nanofiber and the ethylene-vinyl acetate copolymer, the tensile strength, bending strength, notched impact strength and ring stiffness are improved, but the tensile performance at 70℃ is not obviously improved, which shows that the synergistic performance of any two materials is improved compared with adding one material alone, but it is not as obvious as adding the three materials.

[0116] According to the data in Table 2, when the composite elastomer and the talc filled polypropylene short fiber are not added, the tensile strength, bending strength, notched impact strength and ring stiffness of the MPP pipe are obviously lower than those of the conventional MPP pipe, which shows that the addition of the composite elastomer and the talc filled polypropylene short fiber can not only play the role of filler, but also synergistically improve the tensile strength, bending strength, notched impact strength and ring stiffness of the MPP pipe.

[0117] According to the data in Table 2, when the MPP pipe is not heat treated, the tensile strength is reduced compared with the MPP pipe that is heat treated, especially the tensile strength at 23℃ is reduced by about 6%, and the tensile strength at 70℃ is reduced by about 4.3%, which shows that heat treatment can effectively improve the tensile performance of the MPP pipe at room temperature. The bending strength, simply supported beam impact strength and ring stiffness are not obviously affected.

[0118] The above has carried out the detailed introduction to the MPP pipe and its preparation method for enhancing the tensile strength provided by the present application. The description of the specific embodiments is only for helping to understand the method of the present application and its core idea. It should be pointed out that for the ordinary skilled in the art, without departing from the principles of the present application, the present application can be improved and modified, and these improvements and modifications also fall within the scope of protection of the claims of the present application.

[0119] It needs to be specially pointed out that: the specific experimental steps or conditions are not specified in the examples, which can be carried out according to the conventional experimental steps described in the literature or the operation or conditions. The reagents or instruments used are not specified by the manufacturer, which are conventional reagent products that can be obtained by purchase.

[0120] The above examples are for better further understanding of the present application, and do not limit the content and protection scope of the present application, and any person under the inspiration of the present application or the combination of the present application with other existing technical features falls within the protection scope of the present application.

Claims

1. An MPP pipe with enhanced tensile strength, characterized in that, The raw materials include the following parts by weight: 80-99 parts polypropylene, 10-25 parts composite elastomer, 20-42 parts polypropylene fiber, 2-5 parts heat stabilizer, 1-2 parts antioxidant, 1-4 parts lubricant, and 0.5-1 part coupling agent; the polypropylene includes copolymer polypropylene and grafted polypropylene, the melt index of the copolymer polypropylene is 1.5-2.8 g / 10 min; the addition ratio of copolymer polypropylene and grafted polypropylene is 10:(1-2.5); the grafted polypropylene is at least one of ethylene grafted polypropylene, styrene grafted polypropylene, and methyl methacrylate grafted polypropylene; the preparation of the composite elastomer includes the following steps: Ethylene propylene diene monomer (EPDM) rubber and ethylene-vinyl acetate copolymer are placed in a mixing device and stirred at 120-140℃ for 5-10 minutes. Then, silicone oil and nanofibers are added, and stirring is continued for 10-30 minutes. The mixture is then transferred to an extruder for extrusion and granulation to obtain a composite elastomer.

2. The MPP pipe with enhanced tensile strength according to claim 1, characterized in that, The polypropylene fiber includes at least one of polypropylene short fiber, polypropylene long fiber, and polypropylene chip fiber.

3. The MPP pipe with enhanced tensile strength according to claim 1, characterized in that, The heat stabilizer is one or more of the following: barium salt heat stabilizers, cadmium salt heat stabilizers, calcium salt heat stabilizers, stearate heat stabilizers, organotin heat stabilizers, and auxiliary heat stabilizers.

4. The MPP pipe with enhanced tensile strength according to claim 1, characterized in that, The antioxidant is at least one of antioxidant 1076, antioxidant 1010, antioxidant 264, antioxidant CA, and antioxidant DNP.

5. The MPP pipe with enhanced tensile strength according to claim 1, characterized in that, The lubricant is at least one of oxidized polyethylene wax, fatty acid amide, and polyurethane lubricant; the coupling agent is at least one of silane coupling agent, titanate coupling agent, and aluminate coupling agent.

6. A method for preparing an MPP pipe with enhanced tensile strength as described in any one of claims 1-5, characterized in that, Includes the following steps: S1. Place polypropylene in a mixer and stir for 5-10 minutes at 110-130℃. Add heat stabilizer and antioxidant, continue stirring for 5-10 minutes, then add composite elastomer, polypropylene fiber, lubricant and coupling agent. Heat to 160-180℃ and stir for 3-6 minutes to obtain the mixture. S2. The mixture processed in step S1 is transferred into a twin-screw extruder. After being extruded by the twin-screw extruder, it is shaped by a spray vacuum shaping box to obtain an MPP tube. S3. Heat-treat the MPP tube from step S2 to obtain an MPP tube with enhanced tensile properties.

7. The preparation method according to claim 6, characterized in that, In step S3, during heat treatment, the MPP tube is placed in an oven and baked at 35-42°C. During the baking process, the rotation speed of the MPP tube is 10-20 r / min, and the dwell time is 30-50 s.

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