Buried modified polypropylene cable protection tube and preparation method thereof

Abstract

The invention discloses a buried modified polypropylene cable protection tube and a preparation method thereof, belonging to the technical field of buried pipelines. By using an inorganic mixture that has been subjected to ultrasonic cavitation treatment, cryogenic treatment and coupling agent surface treatment in sequence as an inorganic modified filler, the compatibility and dispersibility of the inorganic filler and the resin system can be significantly improved under the premise of adding a small amount of coupling agent, thereby solving the problems of low tensile strength, poor smoothness of inner and outer walls of the pipeline and rapid decline in mechanical properties caused by adding a large amount of fillers such as nano calcium carbonate.

Description

Technical Field

[0001] The invention belongs to the technical field of buried pipelines, and in particular relates to a modified polypropylene buried pipe and a preparation method thereof. Background Art

[0002] Pipes made of polypropylene composite materials have the advantages of low density, non-toxicity, odorlessness, excellent mechanical properties such as strength, hardness and stiffness, and good dielectric properties and high-frequency insulation. It is suitable for use as a buried pipe and has good load-bearing capacity. At present, the modification research on polypropylene at home and abroad mainly focuses on blending modification, copolymerization modification, grafting modification and cross-linking modification. For example, the Chinese invention patent with application number 202010398013.4 discloses a modified polypropylene plastic. The modified polypropylene plastic is prepared by adding PE wax and silicone powder. PE wax increases the compatibility of the mixed system, reduces the cohesive force of polypropylene, and promotes the bonding effect between silicone powder and the plastic matrix to be stronger, thereby improving the mechanical properties of polypropylene plastics and improving the toughness of polypropylene plastics. For example, the Chinese invention patent with application number 201210096621.5 discloses a modified polypropylene cable conduit, which improves the impact resistance, compressive resistance and low-temperature brittleness of the material by adding EPDM rubber. However, the current modification methods have problems such as low tensile strength, poor smoothness of the inner and outer walls of the pipe, and rapid decrease in mechanical properties due to the addition of a large amount of inorganic materials for reinforcement during the modification process. Summary of the invention

[0003] In order to overcome the defects of the prior art, the technical problem to be solved by the present invention is: how to simultaneously overcome the problems of low tensile strength, poor surface smoothness and rapid decline in mechanical properties of the modified polypropylene buried pipe.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: the modified polypropylene buried pipe of the present invention comprises the following raw materials in parts by weight:

[0005] 65-80 parts of polypropylene, 15-25 parts of modified filler, 3-6 parts of chlorinated polyethylene and 1-2 parts of lubricant;

[0006] The modified filler is an inorganic mixture which is sequentially subjected to ultrasonic cavitation treatment, deep cryogenic treatment and coupling agent surface treatment, and the inorganic mixture is nano calcium carbonate and aluminum nitride.

[0007] The method for preparing the buried modified polypropylene cable protection tube comprises the following steps:

[0008] S1. After the modified filler, polypropylene and chlorinated polyethylene are dried, the modified filler, polypropylene, chlorinated polyethylene and lubricant are added in sequence under stirring, and stirred evenly to obtain a blend;

[0009] S2, the blended material is melt-extruded and granulated through a twin-screw extruder to obtain a modified polypropylene special material;

[0010] S3. The modified polypropylene special material is extruded, sized and cooled to obtain the buried modified polypropylene cable protection tube.

[0011] The beneficial effects of the present invention are as follows: the inorganic filler is modified by ultrasonic cavitation treatment, cryogenic treatment and coupling agent surface treatment to improve the interface bonding performance, so that the compatibility and dispersibility of the inorganic filler and the resin system can be significantly improved under the premise of adding a small amount of coupling agent, and the problems of low tensile strength, poor smoothness of the inner and outer walls of the pipeline, and rapid decline in mechanical properties caused by adding a large amount of fillers such as nano calcium carbonate are solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a variation trend diagram of the tensile strength of the buried modified polypropylene cable protection tube of Example 1, Comparative Example 1 and Comparative Example 2 according to the specific implementation mode of the present invention;

[0013] Figure 2 It is a variation trend diagram of the bending strength of the buried modified polypropylene cable protection tube of Example 1, Comparative Example 1 and Comparative Example 2 according to the specific implementation mode of the present invention;

[0014] Figure 3 Shown is a graph showing the variation trend of the ring stiffness of the buried modified polypropylene cable protection tubes of Example 1, Comparative Example 1 and Comparative Example 2 according to the specific implementation of the present invention. DETAILED DESCRIPTION

[0015] In order to explain the technical content, achieved objectives and effects of the present invention in detail, the following is an explanation in conjunction with the implementation modes and the accompanying drawings.

[0016] The most critical concept of the present invention is to modify the inorganic filler by ultrasonic cavitation treatment, cryogenic treatment and coupling agent surface treatment in sequence.

[0017] The buried modified polypropylene cable protection tube of the present invention comprises the following raw materials in parts by weight:

[0018] 65-80 parts of polypropylene, 15-25 parts of modified filler, 3-6 parts of chlorinated polyethylene and 1-2 parts of lubricant;

[0019] The modified filler is an inorganic mixture which is sequentially subjected to ultrasonic cavitation treatment, deep cryogenic treatment and coupling agent surface treatment, and the inorganic mixture is nano calcium carbonate and aluminum nitride.

[0020] From the above description, it can be seen that the beneficial effects of the present invention are: the inorganic filler is modified by ultrasonic cavitation treatment, cryogenic treatment and coupling agent surface treatment to improve the interface bonding performance, so that the compatibility and dispersibility of the inorganic filler and the resin system can be significantly improved under the premise of adding a small amount of coupling agent, and the problem of low tensile strength, poor smoothness of the inner and outer walls of the pipeline, and rapid decline in mechanical properties caused by adding a large amount of fillers such as nano calcium carbonate is solved.

[0021] Furthermore, the mass ratio of nano calcium carbonate to aluminum nitride is 10-15:1.

[0022] From the above description, it can be seen that aluminum nitride has good thermal conductivity and can increase the thermal conductivity of the obtained pipe. However, in order to ensure the mechanical properties of the pipe, its mass ratio to nano-calcium carbonate should be controlled within 10 to 15:1.

[0023] Furthermore, the preparation method of the modified filler is: nano calcium carbonate and aluminum nitride are mixed and ball-milled for 1 to 3 minutes to obtain an inorganic mixture, the inorganic mixture is subjected to ultrasonic cavitation treatment using water as a medium, and after drying, it is subjected to deep freezing treatment below -130°C, and then a coupling agent of 0.1 to 0.5% by mass of the inorganic mixture is added and mixed and stirred to obtain the modified filler.

[0024] From the above description, it can be seen that the ball milling time should not be too long. Otherwise, it will cause agglomeration and affect the effects of subsequent ultrasonic cavitation treatment and cryogenic treatment.

[0025] Furthermore, the power of the ultrasonic cavitation treatment is 20000-30000 Hz, the time is 12-20 min. Furthermore, the temperature of the cryogenic treatment is -130°C to -150°C, the time is 1-2 h, and the cooling rate is 10-20°C / min, preferably 15°C / min.

[0026] Furthermore, after adding the coupling agent, the mixing rate is 1000-1300 r / min and the mixing time is 6-8 min.

[0027] Ultrasonic cavitation treatment can produce local high temperature, high pressure environment, and large instantaneous force, which can better impact and disperse the polymerization of inorganic mixtures. After ultrasonic cavitation treatment, the inorganic mixture is cryogenically treated, and the pores on the surface of aluminum nitride are enlarged, which is combined with a large part of nano-calcium carbonate. Compared with direct cryogenic treatment, it can further improve the modification effect, and the inorganic particles are better combined with the coupling agent in the later stage. It should be noted that ultrasonic cavitation treatment should be carried out first and then cryogenic treatment, otherwise it will increase the edges and corners on the surface of inorganic particles, resulting in reduced mechanical properties of the modified pipe.

[0028] Furthermore, the silane coupling agent is selected from one or both of KH-550 and KH-570.

[0029] Furthermore, the polypropylene is a random copolymer polypropylene; the model is 3003, produced by Formosa Plastics in Taiwan, China; the model is T30S3, produced by Zhongjing Petrochemical; or the model is EPS30R, produced by Dushanzi Petrochemical; or the model is K8003, produced by Dushanzi Petrochemical.

[0030] From the above description, it can be seen that random copolymer polypropylene can provide the pipe with better impact resistance and heat resistance.

[0031] Furthermore, the particle size of the nano calcium carbonate is 100-800 nm, and the particle size of the aluminum nitride is 1-5 μm. The nano calcium carbonate is rose crystal nano calcium carbonate from Fujian Wanqi Non-metallic Materials Co., Ltd.

[0032] Furthermore, the lubricant is calcium stearate, silicone, oleamide, erucamide or polyethylene wax.

[0033] Furthermore, it also includes 0.5 to 2 parts of color powder.

[0034] The method for preparing the buried modified polypropylene cable protection tube comprises the following steps:

[0035] S1. After the modified filler, polypropylene and chlorinated polyethylene are dried, the modified filler, polypropylene, chlorinated polyethylene and lubricant are added in sequence under stirring, and stirred evenly to obtain a blend;

[0036] S2, the blended material is melt-extruded and granulated through a twin-screw extruder to obtain a modified polypropylene special material;

[0037] S3. The modified polypropylene special material is extruded, sized and cooled to obtain the buried modified polypropylene cable protection tube.

[0038] Furthermore, the stirring rate in S1 is 600-800 r / min, the stirring time after adding all the raw materials is 30-60 min, and the drying temperature is 80°C.

[0039] Furthermore, in S2, the screw speed is 200-260 r / min, and the processing temperature is 150-215°C.

[0040] Furthermore, the operating parameters of the twin-screw extruder are: zone 1 temperature is 150°C, zone 2 temperature is 175°C, zone 3 temperature is 205°C, zone 4 temperature is 215°C, zone 5 temperature is 185°C, die head temperature is 185°C, feed speed is 210r / min, and screw speed is 220r / min.

[0041] Furthermore, the extrusion molding rate in S3 is preferably 1.8 m / min.

[0042] Example 1

[0043] The buried modified polypropylene cable protection tube includes the following raw materials:

[0044] Random copolymer polypropylene (3003) 80kg, modified filler 20kg, chlorinated polyethylene 4kg and lubricant 1kg;

[0045] The lubricant is calcium stearate, model S100, from Hunan Shaoyang Tiantang Auxiliary Chemical Co., Ltd.

[0046] The preparation method of the modified filler is as follows: nano calcium carbonate and aluminum nitride are mixed and ball-milled for 90 seconds to obtain an inorganic mixture, the inorganic mixture is subjected to ultrasonic cavitation treatment using water as a medium, the inorganic mixture is dried and cooled at a rate of 15° C. / min, and then deep-cold treated at -148 to -150° C. for 1.5 hours, and then a coupling agent of 0.3% by weight of the inorganic mixture is added and mixed and stirred to obtain the modified filler;

[0047] The silane coupling agent is a mixture of KH-550 and KH-570 in a mass ratio of 1:1;

[0048] The mass ratio of nano-calcium carbonate and aluminum nitride is 12:1;

[0049] The particle size of the nano calcium carbonate is 100-800 nm, which is a rose crystal nano calcium carbonate, and the particle size of the aluminum nitride is 1-5 μm;

[0050] The power of ultrasonic cavitation treatment was 30000 Hz and the time was 12 min.

[0051] The method for preparing the buried modified polypropylene cable protection tube of Example 1 comprises the following steps:

[0052] S1, modified filler, polypropylene, chlorinated polyethylene, after drying, add modified filler, polypropylene, chlorinated polyethylene and lubricant in sequence under stirring at 600r / min, and stir for 45min to obtain a blend;

[0053] S2, the blended material is melt-extruded and granulated through a twin-screw extruder to obtain a modified polypropylene special material;

[0054] The working parameters of the twin-screw extruder are: the temperature of zone 1 is 150℃, the temperature of zone 2 is 175℃, the temperature of zone 3 is 205℃, the temperature of zone 4 is 215℃, the temperature of zone 5 is 185℃, the die temperature is 185℃, the feed speed is 210r / min, and the screw speed is 220r / min;

[0055] S3, modified polypropylene special material is extruded at 1.8m / min, sized and cooled to obtain buried modified polypropylene cable protection tube.

[0056] Example 2

[0057] The buried modified polypropylene cable protection tube includes the following raw materials:

[0058] Random copolymer polypropylene (T30S) 65kg, modified filler 15kg, chlorinated polyethylene 3kg and lubricant 1.2kg;

[0059] The lubricant is polyethylene wax.

[0060] The preparation method of the modified filler is as follows: nano calcium carbonate and aluminum nitride are mixed and ball-milled for 1 minute to obtain an inorganic mixture, the inorganic mixture is subjected to ultrasonic cavitation treatment using water as a medium, the inorganic mixture is dried and cooled at a rate of 10° C. / min, and then deep-cold treated at -135 to -138° C. for 2 hours, and then a coupling agent of 0.5% by weight of the inorganic mixture is added and mixed and stirred to obtain the modified filler;

[0061] The silane coupling agent is a mixture of KH-550 and KH-570 in a mass ratio of 1:1;

[0062] The mass ratio of nano-calcium carbonate and aluminum nitride is 15:1;

[0063] The particle size of the nano calcium carbonate is 100-800 nm, which is a rose crystal nano calcium carbonate, and the particle size of the aluminum nitride is 1-5 μm;

[0064] The power of ultrasonic cavitation treatment was 25000 Hz and the time was 18 min.

[0065] The method for preparing the buried modified polypropylene cable protection tube of Example 2 comprises the following steps:

[0066] S1, modified filler, polypropylene, chlorinated polyethylene, after drying, add modified filler, polypropylene, chlorinated polyethylene and lubricant in sequence under stirring at 700r / min, and stir for 60min to obtain a blend;

[0067] S2, the blended material is melt-extruded and granulated through a twin-screw extruder to obtain a modified polypropylene special material;

[0068] The working parameters of the twin-screw extruder are: the temperature of zone 1 is 150℃, the temperature of zone 2 is 175℃, the temperature of zone 3 is 205℃, the temperature of zone 4 is 215℃, the temperature of zone 5 is 185℃, the temperature of die head is 185℃, the feeding speed is 210r / min, and the screw speed is 200r / min;

[0069] S3, modified polypropylene special material is extruded at 1.9m / min, sized and cooled to obtain buried modified polypropylene cable protection tube.

[0070] Example 3

[0071] The buried modified polypropylene cable protection tube includes the following raw materials:

[0072] Random copolymer polypropylene (EPS30R) 70kg, modified filler 22kg, chlorinated polyethylene 5kg and lubricant 3kg;

[0073] The lubricant is silicone.

[0074] The preparation method of the modified filler is as follows: nano calcium carbonate and aluminum nitride are mixed and ball-milled for 2 minutes to obtain an inorganic mixture, the inorganic mixture is subjected to ultrasonic cavitation treatment using water as a medium, the inorganic mixture is dried and cooled at 20°C / min, and then deep-cold treated at -138 to -140°C for 1 hour, and then 0.1% of the mass of the inorganic mixture is added with a coupling agent KH-550, mixed and stirred to obtain a modified filler;

[0075] The mass ratio of nano-calcium carbonate and aluminum nitride is 13:1;

[0076] The particle size of the nano calcium carbonate is 100-800 nm, which is a rose crystal nano calcium carbonate, and the particle size of the aluminum nitride is 1-5 μm;

[0077] The power of ultrasonic cavitation treatment was 20000 Hz and the time was 20 min.

[0078] The method for preparing the buried modified polypropylene cable protection tube of Example 3 comprises the following steps:

[0079] S1, modified filler, polypropylene, chlorinated polyethylene, after drying, add modified filler, polypropylene, chlorinated polyethylene and lubricant in sequence under stirring at 800r / min, and stir for 30min to obtain a blend;

[0080] S2, the blended material is melt-extruded and granulated through a twin-screw extruder to obtain a modified polypropylene special material;

[0081] The working parameters of the twin-screw extruder are: zone 1 temperature is 150°C, zone 2 temperature is 175°C, zone 3 temperature is 205°C, zone 4 temperature is 215°C, zone 5 temperature is 185°C, die head temperature is 185°C, feed speed is 210r / min, screw speed is 260r / min;

[0082] S3. The modified polypropylene special material is extruded at 2m / min, sized and cooled to obtain the buried modified polypropylene cable protection tube.

[0083] Example 4

[0084] The buried modified polypropylene cable protection tube includes the following raw materials:

[0085] Random copolymer polypropylene (K8003) 75kg, modified filler 25kg, chlorinated polyethylene 6kg, lubricant 1.5kg and color powder 1kg;

[0086] The lubricant is oleamide.

[0087] The preparation method of the modified filler is as follows: nano calcium carbonate and aluminum nitride are mixed and ball-milled for 3 minutes to obtain an inorganic mixture, the inorganic mixture is subjected to ultrasonic cavitation treatment using water as a medium, the inorganic mixture is dried and cooled at a rate of 18° C. / min, and then deep-cold treated at -145 to -148° C. for 1.2 hours, and then 0.2% of the mass of the inorganic mixture is added with a coupling agent KH-570, mixed and stirred to obtain the modified filler;

[0088] The mass ratio of nano-calcium carbonate and aluminum nitride is 14:1;

[0089] The particle size of the nano calcium carbonate is 100-800 nm, which is a rose crystal nano calcium carbonate, and the particle size of the aluminum nitride is 1-5 μm;

[0090] The power of ultrasonic cavitation treatment was 28000 Hz and the time was 15 min.

[0091] The preparation method of the buried modified polypropylene cable protection tube of Example 4 is the same as the preparation method of the buried modified polypropylene cable protection tube of Example 1, wherein the color powder is added to S1 after the modified filler.

[0092] According to the above formula and method, the single-layer pipe with DN200 and wall thickness of 4mm is processed.

[0093] Comparative Example 1: The only difference from Example 1 is that the ultrasonic cavitation treatment and cryogenic treatment are not performed.

[0094] Comparative Example 2: The only difference from Example 1 is that the order of ultrasonic cavitation treatment and cryogenic treatment is exchanged.

[0095] Table 1

[0096]

[0097]

[0098] The pipes of Examples 1-2 and Comparative Examples 1-2 were cut into 6 samples each, and the samples were placed in a constant temperature water bath at 80°C, filled with water and pressurized to 0.82MPa. After aging in the constant temperature water bath for 10 days, three samples were taken from each group for mechanical property testing. After aging for 20 days, the remaining three samples were taken from each group for mechanical property testing. The results are shown in Table 2 (10 days) and Table 3 (20 days), and the test standards are the same as those in Table 1.

[0099] Table 2

[0100]

[0101] Table 3

[0102]

[0103]

[0104] It can be seen that on the 20th day of the accelerated aging experiment, the tensile strength, bending strength and ring stiffness of Comparative Example 1 which did not use modified fillers decreased significantly, that is, decreased rapidly, while although the performance of Example 1 which used modified fillers also decreased, the decrease in mechanical properties slowed down; at the same time, by comparing Example 1 and Comparative Example 2, it can be seen that the change in the order of the processing steps in the modification process will also affect the mechanical properties of the final product to a certain extent.

[0105] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention's specification and drawings, or directly or indirectly applied in related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. Buried modified polypropylene cable protection tube, characterized in that: The invention comprises the following raw materials in parts by weight: 65-80 parts of polypropylene, 15-25 parts of modified filler, 3-6 parts of chlorinated polyethylene and 1-2 parts of lubricant; The modified filler is an inorganic mixture that has been subjected to ultrasonic cavitation treatment, deep cryogenic treatment and coupling agent surface treatment in sequence, and the inorganic mixture is a mixture of nano calcium carbonate and aluminum nitride.

2. The buried modified polypropylene cable protection tube according to claim 1, characterized in that: The mass ratio of the nano calcium carbonate to aluminum nitride is 10-15:

1.

3. The buried modified polypropylene cable protection tube according to claim 1, characterized in that: The preparation method of the modified filler is as follows: nano calcium carbonate and aluminum nitride are mixed and ball-milled for 1 to 3 minutes to obtain an inorganic mixture, the inorganic mixture is subjected to ultrasonic cavitation treatment using water as a medium, the inorganic mixture is dried and deep-cold treated below -130°C, and then a coupling agent of 0.1 to 0.5% by mass of the inorganic mixture is added, mixed and stirred to obtain the modified filler.

4. The buried modified polypropylene cable protection tube according to claim 1, characterized in that: The polypropylene is random copolymer polypropylene.

5. The buried modified polypropylene cable protection tube according to claim 1, characterized in that: The particle size of the nano calcium carbonate is 100-800 nm, and the particle size of the aluminum nitride is 1-5 μm.

6. The buried modified polypropylene cable protection tube according to claim 1, characterized in that: The lubricant is calcium stearate, silicone, oleamide, erucamide or polyethylene wax.

7. The buried modified polypropylene cable protection tube according to claim 1, characterized in that: It also includes 0.5 to 2 parts of color powder.

8. The method for preparing the buried modified polypropylene cable protection tube according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1. Add modified filler, polypropylene, chlorinated polyethylene and lubricant in sequence under stirring, and stir evenly to obtain a blend; S2, the blended material is melt-extruded and granulated through a twin-screw extruder to obtain a modified polypropylene special material; S3. The modified polypropylene special material is extruded, sized and cooled to obtain the buried modified polypropylene cable protection tube.

9. The method for preparing the buried modified polypropylene cable protection tube according to claim 8, characterized in that: The stirring rate in S1 is 600-800 r / min, and the stirring time after adding all the raw materials is 30-60 min.

10. The method for preparing the buried modified polypropylene cable protection tube according to claim 8, characterized in that: In S2, the screw speed is 200-260 r / min and the processing temperature is 150-215°C.

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