A production process of a corrugated pipe and equipment used therefor

Abstract

The present invention discloses a production process of a corrugated pipe and the equipment used therefor, relating to the field of pipe production. The production process of the corrugated pipe comprises the following steps: S1, performing core mold preheating and inner layer winding forming operations at the first processing station; S2, transferring the wound inner layer and the core mold to the second processing station; S3, introducing a polypropylene single-wall corrugated pipe as an auxiliary support for the outer layer, and extruding a polyethylene tape, after the polyethylene tape completely covers the surface of the polypropylene single-wall corrugated pipe, winding and overlapping the polypropylene single-wall corrugated pipe covered with the polyethylene tape at the blank seam of the inner layer; S4, uniformly cooling and shaping the finished product of step S3; when performing the winding work of the polyethylene tape, the temperature of the polyethylene tape is 25-35 °C higher than that of the inner layer. The present application can improve the problems of "outer wall ellipse and inner layer thinning" of the corrugated pipe, is beneficial to improving the pipe structure height and ring stiffness, and can also ensure the stable combination of the inner layer and the outer layer.

Description

Technical Field

[0001] The present application relates to the field of pipeline production, and in particular to a production process of a corrugated pipe and the equipment used therefor. Background Art

[0002] High-density polyethylene (HDPE) wound structured wall pipe type B, commonly known as "corrugated pipe". The corrugated pipe is a special structured wall pipe with high-density polyethylene resin as the main raw material. After the inner layer is formed by the hot-state winding molding process, a polyethylene tape is immediately used to wrap the polypropylene single-wall corrugated pipe (i.e., the outer layer) and wind it around the outer periphery of the inner layer as an auxiliary support structure.

[0003] Currently, in the existing process of producing corrugated pipes, the inner and outer layers are wound simultaneously, that is, the inner layer and the outer layer are wound at the same station and are almost carried out simultaneously. The advantage of this method is that the inner layer and the outer layer can be firmly combined together. However, there are also the following disadvantages: The shrinkage rate of high-density polyethylene resin is 2-4%. In the forming stage of the outer wall material, since the wall material is still in a molten state, the wall material cools and shrinks to generate stress, causing the outer wall to shrink from the outside to the inside, and ultimately resulting in the sinking of the polypropylene single-wall corrugated pipe, squeezing the inner layer material of the corrugated pipe, so that the actually produced pipe is as Figure 1 : The outer wall of the pipe is oval, and the polypropylene single-wall corrugated pipe of the outer layer is embedded into the inner layer, resulting in the thinning of the inner layer, and the excess material accumulates under the oval outer wall. This situation seriously reduces the structural height of the outer wall, and further greatly reduces the ring stiffness of the pipe. At the same time, the inner layer of the pipe is too thin and is easily damaged by external forces, affecting the overall quality and service life of the pipe and unable to fully meet the engineering requirements. Summary of the Invention

[0004] In order to improve the problem that the existing process is prone to produce corrugated pipes with oval outer walls and thinning inner layers, resulting in a great reduction in the performance of corrugated pipes, the present application provides a production process of a corrugated pipe and the equipment used therefor.

[0005] A production process of a corrugated pipe includes the following steps:

[0006] S1. Perform core mold preheating and inner layer winding molding operations at the first processing station;

[0007] S2. Transfer the wound inner layer and the core mold as a whole to the second processing station, and the transfer process should be stable;

[0008] S3. Introduce a polypropylene single-wall corrugated pipe as an auxiliary support for the outer layer, and extrude a polyethylene tape. After the polyethylene tape completely covers the surface of the polypropylene single-wall corrugated pipe, wind and lap the polypropylene single-wall corrugated pipe covered with the polyethylene tape at the joint of the inner layer blank, that is, complete the winding molding operation of the outer layer;

[0009] S4. Uniformly cool and shape the finished product in step S3;

[0010] Among them, when winding the polyethylene tape, the temperature of the polyethylene tape is 25 - 35 °C higher than that of the inner layer.

[0011] Different from the existing production process of winding the inner and outer layers of the corrugated pipe simultaneously, the winding of the inner layer of the corrugated pipe in this application and the polyethylene tape (outer wall) is carried out after the overall winding of the inner layer of the corrugated pipe is completed. And when winding the polyethylene tape, the temperature difference between the polyethylene tape and the inner layer is controlled within the range of 25 - 35 °C. The purpose is to let the inner layer material cool to a certain extent first, making the texture of the inner layer slightly harder. When winding the polyethylene tape, it can reduce the influence of the cooling shrinkage of the polyethylene tape on its own non-circularity and the thickness of the inner layer structure, and can improve the problems of "outer wall ellipse and inner layer thinning" of the corrugated pipe, which is beneficial to improving the structural height and ring stiffness of the pipe. At the same time, the appropriate temperature difference can also ensure the stable combination of the inner layer and the outer layer.

[0012] Among them, the temperature difference between the polyethylene tape and the inner layer should not be too large. If it is too large, it is easy to cause the outer layer and the inner layer to be not firmly combined, and the outer layer and the inner layer are easy to delaminate due to external impact during subsequent use. The temperature difference between the polyethylene tape and the inner layer should not be too small either. If it is too small, it is easy to increase the influence of the outer wall shrinkage stress on its own non-circularity and the thickness of the inner layer structure. When the outer wall is elliptical, the structural height of the pipe decreases, affecting the ring stiffness of the pipe. When the inner layer is too thin, the pipe is easily damaged by external forces, affecting the overall quality and service life of the pipe, and cannot fully meet the engineering requirements.

[0013] Preferably, the polyethylene tape includes a surface layer and a inner layer, the shrinkage rate of the surface layer is 1.5 - 1.7%, and the shrinkage rate of the inner layer is 2 - 2.5%.

[0014] In this application, a polyethylene tape with a two-layer structure is preferably used, and the shrinkage rates of the two layers are inconsistent. The shrinkage rate of the surface layer is smaller than that of the inner layer, but the toughness is slightly worse than that of the inner layer. The combination of the surface layer and the inner layer with different shrinkage rates is beneficial to taking into account the low radial shrinkage and high impact resistance of the polyethylene tape. Among them, the low shrinkage rate of the surface layer of the polyethylene tape enhances the deformation resistance of the polyethylene tape against external shrinkage, and preferentially shapes and forms a rigid framework during the cooling process, restricting the radial shrinkage of the overall polyethylene tape, thereby reducing the elliptical deformation of the outer wall caused by uneven shrinkage. In addition, after the surface layer is shaped, when the inner layer shrinks, the stress is mainly released along the axial direction, rather than radially squeezing the surface layer, thereby reducing the compression effect of the surface layer on the inner layer of the corrugated pipe and further improving the problem of thinning of the inner layer of the corrugated pipe.

[0015] Preferably, the shrinkage rate difference between the inner layer and the surface layer is 0.3 - 0.8%.

[0016] In this application, the shrinkage rate difference between the inner layer and the outer layer is controlled between 0.3% and 0.8%, which is beneficial to reducing the risk of interlayer separation between the inner layer and the outer layer, and is also beneficial to further reducing the out-of-roundness of the outer wall.

[0017] Preferably, the raw materials for preparing the outer layer include 1.5-2 wt% of amino-silane coupling agent modified calcium carbonate, 2.5-3 wt% of PE organic masterbatch, 0.5-1 wt% of ultra-high molecular weight polyethylene, 1-2 wt% of olefin wax, and the balance of high-density polyethylene. The raw materials for preparing the inner layer include 2-3 wt% of epoxy modified polyolefin elastomer, 2-3 wt% of PE organic masterbatch, and the balance of high-density polyethylene.

[0018] In this application, the shrinkage rate of the outer layer is in the range of 1.5-1.7%, and the shrinkage rate of the inner layer is in the range of 2-2.5%. Moreover, the amino-silane coupling agent modified calcium carbonate in the outer layer can form chemical bonds with the epoxy modified polyolefin elastomer in the inner layer, improving the bonding stability between the outer layer and the inner layer, and preventing the delamination problem caused by the shrinkage rate difference or interface difference between the outer layer and the inner layer.

[0019] Among them, the preparation method of the amino-silane coupling agent modified calcium carbonate is as follows:

[0020] Add 0.2-0.3 parts by weight of amino-silane coupling agent to 100 parts by weight of ethanol solution with a mass concentration of 70-80%. After stirring evenly, add 8-10 parts by weight of calcium carbonate, then heat to 55-65 °C and reflux for 1-1.5 h. Then filter, take the filter residue, wash and dry it to obtain the amino-silane coupling agent modified calcium carbonate.

[0021] Preferably, the molecular weight of the ultra-high molecular weight polyethylene is 4 million - 6 million.

[0022] Preferably, the epoxy modified polyolefin elastomer is POE grafted with glycidyl methacrylate.

[0023] Among them, the raw materials for preparing the POE grafted with glycidyl methacrylate include glycidyl methacrylate, POE elastomer, peroxide initiator, and antioxidant in a weight ratio of (2.5-3.5):100:(0.03-0.05):(0.1-0.2).

[0024] In this application, controlling the grafting rate of glycidyl methacrylate is beneficial to taking into account the low radial shrinkage and high impact resistance of the polyethylene tape, and preventing the problem of the decrease in the interfacial bonding strength between the outer layer and the inner layer caused by too high or too low grafting rate.

[0025] Further preferably, the thickness ratio of the outer layer to the inner layer is 1:(3-4).

[0026] In this application, the thickness ratio of the control surface layer to the inner layer is 1:(3 - 4), which is beneficial to taking into account the low radial shrinkage and high impact resistance of the polyethylene tape.

[0027] The melting and extrusion temperatures of the inner layer, surface layer, and inner lining are all 180 - 190 °C.

[0028] In the second aspect, the equipment adopted in the production process of a kind of corrugated pipe provided by this application adopts the following technical solution:

[0029] An equipment adopted in the production process of a kind of corrugated pipe includes:

[0030] A chassis, on one of the two opposite sides of the chassis, a first processing station is provided, and on the other opposite side, a second processing station is provided; a core mold is placed at the first processing station, and the core mold is connected to a heating mechanism for heating the core mold, and the core mold completed with inner layer winding is placed at the second processing station;

[0031] An inner layer extrusion mechanism, which is used for heating, melting, and extruding inner layer raw materials;

[0032] A first moving mechanism, which controls the inner layer extrusion mechanism to move along the length direction of the core mold, and through the cooperation of a winding mechanism, winds the extruded inner layer raw materials on the surface of the core mold at the first processing station;

[0033] A polypropylene single-wall corrugated pipe feeding mechanism, which transports the polypropylene single-wall corrugated pipe to the core mold completed with inner layer winding at the second processing station;

[0034] A polyethylene tape extrusion mechanism, which includes an inner lining extrusion mechanism and a surface layer extrusion mechanism. First, the inner lining raw materials extruded by the inner lining extrusion mechanism are used for inner coating of the polypropylene single-wall corrugated pipe, and then the surface layer raw materials extruded by the surface layer extrusion mechanism are used for outer coating of the polypropylene single-wall corrugated pipe to obtain an outer layer material;

[0035] A second moving mechanism, which controls the polyethylene tape extrusion mechanism to move along the length direction of the core mold, and through the cooperation of a winding mechanism, winds the outer layer material on the core mold completed with inner layer winding at the second processing station;

[0036] A cooling station, which naturally cools the pipe completed with outer layer winding.

[0037] To sum up, this application at least includes the following beneficial technical effects:

[0038] (1)The winding of the inner layer of the corrugated pipe of this application and the polyethylene tape (outer pipe wall) is carried out after the overall winding of the inner layer of the corrugated pipe is completed. When carrying out the winding work of the polyethylene tape, the temperature difference between the polyethylene tape and the inner layer is controlled within the range of 25-35 °C. The purpose is to let the inner layer material cool to a certain extent and make the texture of the inner layer slightly harder, so that when winding the polyethylene tape, the influence of the cooling shrinkage of the polyethylene tape on its own non-roundness and the thickness of the inner layer structure can be reduced, the problems of "elliptical outer wall and thinning of the inner layer" of the corrugated pipe can be improved, which is beneficial to improving the structural height and ring stiffness of the pipe. At the same time, the appropriate temperature difference can also ensure the stable combination of the inner layer and the outer layer.

[0039] (2)In this application, it is preferably to use a polyethylene tape with a two-layer structure, and the shrinkage rates of the two layers are inconsistent. The shrinkage rate of the surface layer is smaller than that of the inner layer, but the toughness is slightly worse than that of the inner layer. The combination of the surface layer and the inner layer with different shrinkage rates is beneficial to taking into account the low radial shrinkage and high impact resistance of the polyethylene tape. Among them, the low shrinkage rate of the surface layer of the polyethylene tape enhances the deformation resistance of the polyethylene tape against external shrinkage, takes shape first and forms a rigid skeleton during the cooling process, restricts the radial shrinkage of the overall polyethylene tape, thereby reducing the elliptical deformation of the outer wall caused by uneven shrinkage. In addition, after the surface layer is shaped, when the inner layer shrinks, the stress is mainly released along the axial direction, rather than radially extruding the surface layer, thereby reducing the compression effect of the surface layer on the inner layer of the corrugated pipe and further improving the problem of thinning of the inner layer of the corrugated pipe.

[0040] (3)In this application, the shrinkage rate of the surface layer is in the range of 1.5-1.7%, and the shrinkage rate of the inner layer is in the range of 2-2.5%. And the amino-silane coupling agent modified calcium carbonate in the surface layer can form chemical bonds with the epoxy modified polyolefin elastomer in the inner layer, improving the bonding stability between the surface layer and the inner layer and preventing delamination problems caused by shrinkage rate differences or interface differences between the surface layer and the inner layer. Description of the Drawings

[0041] Figure 1 is a cross-sectional view of a corrugated pipe obtained by the existing corrugated pipe production process.

[0042] Figure 2 is a schematic structural diagram of the corrugated pipe production equipment of this application.

[0043] Figure 3 is a cross-sectional view of a corrugated pipe obtained by the corrugated pipe production process of this application.

[0044] Description of the Reference Numerals:

[0045] 1. Chassis; 11. First processing station; 12. Second processing station; 13. Core mold; 2. Inner layer extrusion mechanism; 3. First moving mechanism; 4. Polypropylene single-wall corrugated pipe feeding mechanism; 5. Polyethylene tape extrusion mechanism; 51. Inner layer extrusion mechanism; 52. Surface layer extrusion mechanism; 6. Second moving mechanism; 7. Cooling station. Detailed implementation mode

[0046] The embodiment of the present application discloses a production device for corrugated pipes, as Figure 2 follows:

[0047] Chassis 1, among the two opposite sides of the chassis 1, one side is provided with a first processing station 11, and the other opposite side is provided with a second processing station 12; a core mold 13 is placed at the first processing station 11, and the core mold 13 is connected with a heating mechanism for heating the core mold 13, and the core mold 13 that has completed the inner layer winding is placed at the second processing station 12;

[0048] Inner layer extrusion mechanism 2, which is used for heating and melting and extruding the inner layer raw material;

[0049] First moving mechanism 3, the first moving mechanism 3 controls the inner layer extrusion mechanism 2 to move along the length direction of the core mold 13, and through the cooperation of the winding mechanism, the extruded inner layer raw material is wound on the surface of the core mold 13 at the first processing station 11;

[0050] Polypropylene single-wall corrugated pipe feeding mechanism 4, which transports the polypropylene single-wall corrugated pipe to the core mold 13 that has completed the inner layer winding at the second processing station 12;

[0051] Polyethylene tape extrusion mechanism 5, the polyethylene tape extrusion mechanism 5 includes an inner layer extrusion mechanism 51 and a surface layer extrusion mechanism 52. First, the inner layer raw material extruded by the inner layer extrusion mechanism 51 is used for inner coating of the polypropylene single-wall corrugated pipe, and then the surface layer raw material extruded by the surface layer extrusion mechanism 52 is used for outer coating of the polypropylene single-wall corrugated pipe to obtain the outer layer material;

[0052] Second moving mechanism 6, the second moving mechanism 6 controls the polyethylene tape extrusion mechanism 5 to move along the length direction of the core mold 13, and through the cooperation of the winding mechanism, the outer layer material is wound on the core mold 13 that has completed the inner layer winding at the second processing station 12;

[0053] Cooling station 7, the cooling station 7 is used for holding the pipe that has completed the outer layer winding, so that the pipe is naturally cooled.

[0054] The following further illustrates the present application in combination with specific experiments.

[0055] Preparation example

[0056]

Preparation example 1

[0057] A glycidyl methacrylate graft-modified POE, comprising 2.5 kg of glycidyl methacrylate, 100 kg of a POE elastomer (Mitsui DF710 of Japan), 0.03 kg of diisopropylbenzene peroxide, and 0.1 kg of antioxidant 1010.

[0058] In this preparation example, the preparation method of the glycidyl methacrylate graft-modified POE is as follows:

[0059] Put glycidyl methacrylate, POE elastomer, diisopropylbenzene peroxide, and antioxidant 1010 into an extruder according to the ratio, melt and extrude at 170 - 190 °C, and pelletize to obtain the glycidyl methacrylate graft-modified POE.

[0060]

Preparation Example 2

[0061] A glycidyl methacrylate graft-modified POE, comprising 3.5 kg of glycidyl methacrylate, 100 kg of a POE elastomer (Mitsui DF710 of Japan), 0.05 kg of diisopropylbenzene peroxide, and 0.2 kg of antioxidant 1010.

[0062] In this preparation example, the preparation method of the glycidyl methacrylate graft-modified POE is as follows:

[0063] Put glycidyl methacrylate, POE elastomer, diisopropylbenzene peroxide, and antioxidant 1010 into an extruder according to the ratio, melt and extrude at 170 - 190 °C, and pelletize to obtain the glycidyl methacrylate graft-modified POE.

[0064]

Preparation Example 3

[0065] A glycidyl methacrylate graft-modified POE, different from

Preparation Example 1

[0066]

Preparation Example 4

[0067] A preparation method of an amino-silane coupling agent KH550 modified calcium carbonate is as follows:

[0068] Add 0.25 kg of amino-silane coupling agent KH550 to 100 kg of an ethanol solution with a mass concentration of 75%, stir evenly, add 8 kg of calcium carbonate, then heat to 60 °C and reflux for 1 h, then filter, take the filter residue, wash and dry to obtain the amino-silane coupling agent KH550 modified calcium carbonate. Examples

[0069]

Example 1

[0070] A production process of a corrugated pipe, comprising the following steps:

[0071] S1. Preheat the core mold at the first processing station, and then put 98 wt% high-density polyethylene (Taiwan Plastics 8001 from Taiwan, China) and 2 wt% PE organic masterbatch (the mass content of solvent black 7 is 40%) into the inner layer extrusion mechanism. Melt and extrude at 180 - 190 °C to obtain the inner layer sheet, and then control the inner layer sheet to wind along the length direction of the core mold through the winding mechanism and the first moving mechanism;

[0072] S2. After completing the inner layer winding and forming operation, transfer the core mold with the inner layer wound integrally to the second processing station, and the transfer process should be stable.

[0073] S3. Put 1.5 wt% calcium carbonate modified with amino silane coupling agent KH550 prepared in

Preparation Example 4

Preparation Example 1

[0074] S4. Uniformly cool and shape the product in step S3 to avoid rapid cooling.

[0075] In this example, the shrinkage rate of the surface layer is 1.5%, the shrinkage rate of the inner layer is 2.1%, and the shrinkage rate difference between the inner layer and the surface layer is 0.6%.

[0076]

Example 2

[0077] A production process of a corrugated pipe, different from [Example 1] in that: in step S3, the surface extrusion mechanism inputs 2 wt% of calcium carbonate modified by amino silane coupling agent KH550 prepared in [Preparation Example 4], 3 wt% of PE organic color masterbatch (the mass content of solvent black 7 is 40%), 0.5 wt% of ultra-high molecular weight polyethylene (U050 from Korea Petrochemical), 2 wt% of low molecular weight polyethylene wax (polyethylene wax A-C6A), and the balance of high density polyethylene (8001 from Formosa Plastics, Taiwan Province, China); the inner layer extrusion mechanism inputs 3 wt% of glycidyl methacrylate grafted modified POE prepared in [Preparation Example 2], 3 wt% of PE organic color masterbatch (the mass content of solvent black 7 is 40%), and the balance of high density polyethylene (8001 from Formosa Plastics, Taiwan Province, China).

[0078] In this example, the shrinkage rate of the surface layer is 1.5%, the shrinkage rate of the inner layer is 2.1%, and the shrinkage rate difference between the inner layer and the surface layer is 0.6%.

[0079] [Example 3]

[0080] A production process of a corrugated pipe, different from [Example 1] in that: the surface extrusion mechanism inputs 3 wt% of calcium carbonate modified by amino silane coupling agent KH550 prepared in [Preparation Example 4], 3 wt% of PE organic color masterbatch (the mass content of solvent black 7 is 40%), 6 wt% of ultra-high molecular weight polyethylene (U050 from Korea Petrochemical), 2 wt% of low molecular weight polyethylene wax (polyethylene wax A-C6A), and the balance of high density polyethylene (8001 from Formosa Plastics, Taiwan Province, China); the inner layer extrusion mechanism inputs 3 wt% of PE organic color masterbatch (the mass content of solvent black 7 is 40%) and the balance of high density polyethylene (8001 from Formosa Plastics, Taiwan Province, China).

[0081] In this example, the shrinkage rate of the surface layer is 1.3%, the shrinkage rate of the inner layer is 2.5%, and the shrinkage rate difference between the inner layer and the surface layer is 1.2%.

[0082] [Example 4]

[0083] A production process of a corrugated pipe, different from [Example 1] in that: in step S3, the raw material glycidyl methacrylate grafted modified POE input into the inner layer extrusion mechanism is replaced with an equal amount of glycidyl methacrylate grafted modified POE prepared in [Preparation Example 3].

[0084] In this example, the shrinkage rate of the surface layer is 1.5%, the shrinkage rate of the inner layer is 2%, and the shrinkage rate difference between the inner layer and the surface layer is 0.5%.

[0085] Comparative example

[0086] [Comparative Example 1]

[0087] A production process of a corrugated pipe, different from [Example 1] in that:

[0088] In step S3, when winding the outer layer material, the temperature of the inner layer on the core mold is 10 °C lower than the surface temperature.

[0089] [Comparative Example 2]

[0090] A production process of a corrugated pipe, different from [Example 1] in that:

[0091] In step S3, when winding the outer layer material, the temperature of the inner layer on the core mold is 45 °C lower than the surface temperature.

[0092] Performance detection test

[0093] Prepare corrugated pipe specimens with a nominal size of 300 mm, an inner layer wall thickness of 2 mm, and a ring stiffness grade of SN12.5 according to the methods of Examples 1-4 and Comparative Examples 1-2 above, and take the corrugated pipe specimens for the following performance detections.

[0094] (1) Cross-sectional shape of the outer wall: Cut the corrugated pipe along the diameter direction, observe the cross-sectional shape of the outer wall of the corrugated pipe, and record it in Table 1 below.

[0095] (2) Thinnest wall thickness of the inner layer: Cut the corrugated pipe along the diameter direction, take three samples from each of the examples and comparative examples respectively, and take three intersection positions of the outer layer and the inner layer at equal intervals for each sample for detection, and record the average value of the detection data in Table 1 below.

[0096] (3) Ring stiffness: Test according to GB / T9647-2015 "Determination of ring stiffness of thermoplastic pipes", take three samples from each of the examples and comparative examples for detection, and record the average value of the detection data in Table 1 below.

[0097] (4) Oven test: After cutting the corrugated pipe along the diameter direction, put the cut sample into an oven, the oven temperature is 110 °C, and the treatment time is 30 min. Observe whether delamination or cracking occurs at the joints between the inner layer and the surface layer, and between the outer layer and the inner layer of the outer wall, and record the results in Table 2 below.

[0098] Table 1

[0099]

[0100] Table 2

[0101]

[0102] The outer wall interface of the corrugated pipes obtained in Examples 1-4 and Comparative Example 2 of the present application is quasi-circular, as Figure 3As shown. The cross-section of the outer wall of the corrugated pipe obtained in Comparative Example 1 is elliptical, similar to Figure 1 Similar.

[0103] Combined with the detection data in Example 1, Comparative Examples 1-2, and Tables 1-2, it can be seen that when performing the outer winding operation of the corrugated pipe, controlling the temperature difference between the outer polyethylene tape and the inner layer of the corrugated pipe within the range of 25-35 °C is beneficial to improving the problems that the outer wall of the corrugated pipe is elliptical and the inner wall thickness of the inner layer at the fusion joint between the outer layer and the inner layer becomes thinner. At the same time, ensuring the stable combination of the outer layer and the inner layer of the corrugated pipe can effectively improve the ring stiffness of the corrugated pipe and extend the service life of the corrugated pipe.

[0104] Combined with the detection data in Example 1 and Example 3, and Tables 1-2, it can be seen that in Example 3, the incorporation amounts of amino-silane coupling agent KH550 modified calcium carbonate and ultra-high molecular weight polyethylene in the surface layer are increased, and glycidyl methacrylate grafted modified POE is not incorporated in the inner layer. The shrinkage rate difference between the surface layer and the inner layer of the polyethylene tape increases, and delamination is likely to occur between the surface layer and the inner layer after heat treatment, and the ring stiffness of the corrugated pipe also decreases.

[0105] Combined with the detection data in Example 1 and Example 4, and Tables 1-2, it can be seen that in the glycidyl methacrylate grafted modified POE incorporated in the inner layer of Example 4, the grafting rate of glycidyl methacrylate increases. Combining the data in the table, it can be seen that delamination is likely to occur between the surface layer and the inner layer of the polyethylene tape in Example 4 after heat treatment, and the ring stiffness of the corrugated pipe also decreases. Therefore, it is preferred to control the grafting rate of glycidyl methacrylate in the glycidyl methacrylate grafted modified POE within a reasonable range.

[0106] This specific embodiment is only an interpretation of the present application and does not limit the present application. Those skilled in the art can make modifications without creative contributions to this specific embodiment according to needs after reading this specification, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. A production process of a corrugated pipe, characterized in that, It includes the following steps: S1. Perform core mold preheating and inner layer winding forming operations at the first processing station; S2. Transfer the core mold with the inner layer wound integrally to the second processing station smoothly during the transfer process; S3. Introduce a polypropylene single-wall corrugated pipe as the auxiliary support for the outer layer, and extrude a polyethylene tape. After the polyethylene tape completely covers the surface of the polypropylene single-wall corrugated pipe, wind and lap the polypropylene single-wall corrugated pipe covered with the polyethylene tape at the joint of the inner layer blank, thus completing the winding forming operation of the outer layer; S4. Uniformly cool and shape the finished product of step S3; Among them, when winding the polyethylene tape, the temperature of the polyethylene tape is 25 - 35 °C higher than that of the inner layer; The polyethylene tape includes a surface layer and a inner layer; The preparation raw materials of the surface layer include 1.5 - 2wt% amino-silane coupling agent modified calcium carbonate, 2.5 - 3wt% PE organic color masterbatch, 0.5 - 1wt% ultra-high molecular weight polyethylene, 1 - 2wt% olefin wax, and the balance of high-density polyethylene. The preparation raw materials of the inner layer include 2 - 3wt% epoxy modified polyolefin elastomer, 2 - 3wt% PE organic color masterbatch, and the balance of high-density polyethylene; The epoxy modified polyolefin elastomer is prepared by grafting glycidyl methacrylate onto POE; The preparation raw materials of the glycidyl methacrylate grafted POE include glycidyl methacrylate, POE elastomer, peroxide initiator, and antioxidant in a weight ratio of (2.5 - 3.5):100:(0.03 - 0.05):(0.1 - 0.2); 2. The production process of a corrugated pipe according to claim 1, characterized in that: The shrinkage rate of the surface layer is 1.5 - 1.7%, and the shrinkage rate of the inner layer is 2 - 2.5%; 3. The production process of a corrugated pipe according to claim 2, characterized in that: The shrinkage rate difference between the inner layer and the surface layer is 0.3 - 0.8%; 4. The production process of a corrugated pipe according to claim 1, characterized in that: The molecular weight of the ultra-high molecular weight polyethylene is 4 million - 6 million; 5. The production process of a corrugated pipe according to claim 1, characterized in that: The thickness ratio of the surface layer to the inner layer is 1:(3 - 4); 6. The production process of a corrugated pipe according to claim 1, characterized in that: The melting and extrusion temperatures of the inner layer, surface layer, and inner layer are all 180 - 190 °C; 7. An apparatus used in the production process of a corrugated pipe as described in any one of claims 1 - 6, characterized in that, It includes: A chassis. Among the two opposite sides of the chassis, one side is provided with a first processing station, and the other opposite side is provided with a second processing station; the first processing station places the core mold, and the core mold is connected to a heating mechanism for heating the core mold. The second processing station places the core mold with the inner layer wound; An inner layer extrusion mechanism for heating, melting, and extruding the inner layer raw materials; A first moving mechanism that controls the inner layer extrusion mechanism to move along the length direction of the core mold. Through the cooperation of the winding mechanism, the extruded inner layer raw materials are wound on the surface of the core mold at the first processing station; A polypropylene single-wall corrugated pipe feeding mechanism that transports the polypropylene single-wall corrugated pipe to the core mold with the inner layer wound at the second processing station; A polyethylene tape extrusion mechanism that includes an inner layer extrusion mechanism and a surface layer extrusion mechanism. First, the inner layer raw materials extruded by the inner layer extrusion mechanism are used to internally cover the polypropylene single-wall corrugated pipe, and then the surface layer raw materials extruded by the surface layer extrusion mechanism are used to externally cover the polypropylene single-wall corrugated pipe to obtain the outer layer material; A second moving mechanism that controls the polyethylene tape extrusion mechanism to move along the length direction of the mandrel. Through the cooperation of the winding mechanism, the outer layer material is wound around the mandrel that has completed the inner layer winding at the second processing station; A cooling station that naturally cools the pipe after the outer layer winding is completed.

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