A helically wound pipe repair profile and method of preparation thereof by coextrusion

Abstract

This invention discloses a spiral-wound pipe repair profile and its co-extrusion composite preparation method, belonging to the field of pipe repair material preparation technology. This invention utilizes three extruders to independently mix and plasticize the raw materials for the upper and lower rigid PVC surface layers and the middle foamed core layer, then simultaneously extrude them into a three-layer co-extrusion die for one-time molding. This process avoids the cumbersome steps of step extrusion and secondary compounding, achieving continuous production and improving production efficiency. The three layers of molten material are compounded in one step within the die, significantly enhancing the interlayer bonding force and preventing delamination. By precisely controlling the mixing, extrusion, shaping, and cooling parameters of each layer, defects such as uneven profile thickness, uneven foaming, and low dimensional accuracy are overcome. The prepared profile has high dimensional accuracy, stable quality, and combines high strength, high toughness, excellent impact resistance, and sound damping performance, making it suitable for pipe repair needs under complex working conditions.

Description

Technical Field

[0001] This invention relates to the field of pipeline repair material preparation technology, and in particular to a spiral wound pipeline repair profile and its co-extrusion composite process preparation method. Background Technology

[0002] Existing processes for manufacturing spiral-wound pipe repair profiles mostly employ step-by-step extrusion and secondary compounding, which are cumbersome, inefficient, and result in weak interlayer bonding, leading to delamination and peeling, thus affecting the overall stability and service life of the repaired pipe. Furthermore, the lack of precise control over process parameters can cause uneven raw material mixing, extrusion temperature fluctuations, and unreasonable cooling rates, resulting in uneven profile thickness, uneven foaming, and low dimensional accuracy. This further reduces the profile's overall performance, including strength, toughness, impact resistance, and sound damping. Summary of the Invention

[0003] This invention provides a spiral wound pipe repair profile and its co-extrusion composite process preparation method to solve the problems of cumbersome preparation process, low production efficiency, and difficulty in controlling process parameters in the prior art for spiral wound pipe repair profiles, as well as the poor overall performance of the profiles prepared by the above-mentioned preparation process, such as overall strength, toughness, impact resistance, and sound damping performance.

[0004] In a first aspect, the present invention provides a method for preparing a helical wound pipe repair profile using a co-extrusion composite process, the method comprising: Step 100: Obtain the raw materials for the upper rigid PVC surface layer of the pipe repair profile, the raw materials for the middle foamed core layer of the pipe repair profile, and the raw materials for the lower rigid PVC surface layer of the pipe repair profile. Step 200: The raw materials of the upper rigid PVC surface layer are controlled to be mixed according to the first preset conditions, the raw materials of the middle foamed core layer are controlled to be mixed according to the second preset conditions, and the raw materials of the lower rigid PVC surface layer are controlled to be mixed according to the third preset conditions, to obtain the first layer material for forming the upper rigid PVC surface layer, the second layer material for forming the middle foamed core layer, and the third layer material for forming the lower rigid PVC surface layer. Step 300: Using three extruders, the first layer material, the second layer material and the third layer material are plasticized and then simultaneously extruded into a three-layer co-extrusion die for molding to obtain an extruded profile with a three-layer co-extrusion composite structure. Step 400: The extruded profile is subjected to shaping and cooling treatment to obtain the spiral wound pipe repair profile.

[0005] In a second aspect, the present invention provides a spiral wound pipe repair profile, which is prepared by a co-extrusion composite process as described in the first aspect.

[0006] The aforementioned spiral-wound pipe repair profile and its co-extrusion composite process utilize three extruders to independently mix and plasticize the raw materials for the upper rigid PVC surface layer, the middle foamed core layer, and the lower rigid PVC surface layer, then simultaneously extrude them into a three-layer co-extrusion mold for one-time molding. This process avoids the cumbersome steps of step extrusion and secondary compounding, achieving continuous production and improving production efficiency. The three layers are compounded in the mold in a molten state, significantly enhancing the interlayer bonding force and effectively preventing delamination and separation. By precisely controlling the process parameters such as mixing, extrusion, shaping, and cooling of each layer, technical defects such as uneven profile thickness, uneven foaming, and low dimensional accuracy are overcome. Compared with existing technologies, the co-extrusion composite process of this invention produces profiles with high dimensional accuracy and stable quality. Simultaneously, the synergistic effect of the three-layer co-extrusion structure gives the profiles high strength, high toughness, excellent impact resistance, and sound damping performance, making them suitable for pipe repair needs under complex working conditions. Attached Figure Description

[0007] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0008] Figure 1 This is a flowchart of the co-extrusion composite process for preparing the spiral wound pipe repair profile in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the cross-sectional structure of the spiral wound pipe repair profile in Embodiment 10 of the present invention; Figure 3 This is a schematic diagram of the structure of the base plate of the spiral wound pipe repair profile in Embodiment 10 of the present invention; Figure 4 This is a schematic diagram of the foam core structure of the intermediate foam core layer of the spiral wound pipe repair profile provided in Embodiment 10 of the present invention. Detailed Implementation

[0009] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0010] In Example 1, as Figure 1 As shown, this embodiment provides a co-extrusion composite process for preparing a spiral-wound pipe repair profile. The co-extrusion composite process for preparing the spiral-wound pipe repair profile includes: Step 100: Obtain the raw materials for the upper rigid PVC surface layer of the pipe repair profile, the raw materials for the middle foamed core layer of the pipe repair profile, and the raw materials for the lower rigid PVC surface layer of the pipe repair profile. The upper rigid PVC surface layer refers to the solid rigid PVC layer located on the topmost layer of the profile base plate, facing the water flow side of the pipe cavity. It is used to ensure the overall yield strength, ring stiffness, and weather resistance of the pipe repair profile. The middle foamed core layer refers to the PVC foam material layer located between the upper and lower rigid PVC surface layers. It is used to absorb external impact energy and provide sound damping performance. The lower rigid PVC surface layer refers to the solid rigid PVC layer located on the bottommost layer of the profile base plate, facing the inner wall of the old pipe to be repaired. Its formula and properties are consistent with the upper rigid PVC surface layer. Together with the upper rigid PVC surface layer, it is used to ensure the overall yield strength, ring stiffness, and weather resistance of the pipe repair profile, and to provide a stable interlayer bond with the inner wall of the old pipe.

[0011] Step 200: The raw materials of the upper rigid PVC surface layer are controlled to be mixed according to the first preset conditions, the raw materials of the middle foamed core layer are controlled to be mixed according to the second preset conditions, and the raw materials of the lower rigid PVC surface layer are controlled to be mixed according to the third preset conditions, to obtain the first layer material for forming the upper rigid PVC surface layer, the second layer material for forming the middle foamed core layer, and the third layer material for forming the lower rigid PVC surface layer. The first preset condition refers to the pre-set combination of raw material mixing process parameters for the upper rigid PVC surface layer. The second preset condition refers to the pre-set combination of raw material mixing process parameters for the middle foamed core layer. The third preset condition refers to the pre-set combination of raw material mixing process parameters for the lower rigid PVC surface layer. Mixing treatment refers to placing the raw materials of the three layers into their respective dedicated mixers and mixing and dispersing them according to their corresponding preset conditions. The first layer material refers to the uniform rigid PVC dry mix obtained after mixing according to the first preset condition, used for extrusion molding to form the upper rigid PVC surface layer. The second layer material refers to the uniform foamed PVC dry mix obtained after mixing according to the second preset condition, used for extrusion molding to form the middle foamed core layer. The third layer material refers to the uniform rigid PVC dry mix obtained after mixing according to the third preset condition, used for extrusion molding to form the lower rigid PVC surface layer.

[0012] In this embodiment, the first preset condition and the third preset condition are the same.

[0013] Step 300: Using three extruders, the first layer material, the second layer material and the third layer material are plasticized and then simultaneously extruded into a three-layer co-extrusion die for molding to obtain an extruded profile with a three-layer co-extrusion composite structure. The three extruders refer to three independent extrusion units, each used to plasticize the raw materials for the upper rigid PVC surface layer, the middle foamed core layer, and the lower rigid PVC surface layer, respectively. Plasticization refers to the process of transforming powdered or granular solid PVC raw materials (such as resin and various additives) into a uniform, continuous melt with certain fluidity and plasticity through heating, shearing, mixing, and melting within the extruder. Three-layer co-extrusion mold refers to a special composite molding mold with three independent melt flow channels, which respectively transport the melt of the upper rigid PVC surface layer, the middle foamed core layer, and the lower rigid PVC surface layer. The mold cavity is designed according to a preset cross section, so that the three melts are composited in a layered manner in the mold core or mold lip area in an ABA sequence. At the same time, the rigid PVC melt is diverted to form T-shaped longitudinal reinforcing ribs, end lips, sealing strips, male and female locking buckles, etc. The melts of each structure are thermally melted and bonded with the three-layer base plate melt in the mold and are simultaneously shaped. After extrusion, an integrated profile is formed with an ABA three-layer structured profile base plate and the remaining structures of solid rigid PVC (T-shaped longitudinal reinforcing ribs, end lips, sealing strips, male and female locking buckles, etc.). The interlayer bonding is firm and the layers do not mix. Molding process refers to the process where the molten structural elements and the three-layer base plate are thermally melted and bonded together in the mold, simultaneously shaped, and then extruded through the die orifice to initially form a continuous profile with a preset cross-sectional structure (including the profile base plate, T-shaped longitudinal reinforcing ribs, end lips, sealing strips, male and female locking latches). A three-layer co-extrusion composite structure refers to a three-layer integrated structure formed in one piece through a co-extrusion process, without subsequent bonding or splicing. Extruded profiles refer to long strip-shaped plastic products that are continuously produced through an extrusion process, with a fixed cross-sectional shape and a length that can be cut as needed.

[0014] In this embodiment, the extruded profile of the three-layer co-extruded composite structure is a long strip of ABA three-layer co-extruded composite plastic sheet used for pipe repair. The three extruders are three single-screw extruders, or a combination of a twin-screw extruder and a single-screw extruder. Preferably, the extruder used to form the upper rigid PVC surface layer is an SJ60 single-screw extruder, the extruder used to form the middle foamed core layer is an SJ60 twin-screw extruder, and the extruder used to form the lower rigid PVC surface layer is an SJ45 single-screw extruder.

[0015] Step 400: The extruded profile is subjected to shaping and cooling treatment to obtain the spiral wound pipe repair profile.

[0016] The shaping process refers to the operation of rapidly fixing the molten extruded profile from the three-layer co-extrusion die into its final cross-sectional shape, size, and interlayer structure through vacuum adsorption. The cooling process involves cooling the shaped profile to room temperature to stabilize the material dimensions, fully solidify it, and eliminate internal stress. The spiral-wound pipe repair profile refers to a PVC profile with an ABA three-layer co-extruded composite structure, obtained after complete co-extrusion, shaping, shaping, and cooling processes, meeting dimensional and performance standards for trenchless spiral-wound lining repair.

[0017] This embodiment of the co-extrusion composite process for preparing spiral-wound pipe repair profiles utilizes three extruders. The raw materials for the upper rigid PVC surface layer, the middle foamed core layer, and the lower rigid PVC surface layer are independently mixed, plasticized, and then simultaneously extruded into a three-layer co-extrusion mold for one-time molding. This process avoids the cumbersome steps of step extrusion and secondary compounding, achieving continuous production and improving efficiency. The three layers are compounded in a single step within the mold while in a molten state, significantly enhancing interlayer bonding and effectively preventing delamination. By precisely controlling the process parameters such as mixing, extrusion, shaping, and cooling of each layer, technical defects such as uneven profile thickness, uneven foaming, and low dimensional accuracy are overcome. The co-extrusion composite process produces profiles with high dimensional accuracy and stable quality. Simultaneously, the synergistic effect of the three-layer co-extrusion structure gives the profiles high strength, high toughness, excellent impact resistance, and sound damping performance, making them suitable for pipe repair needs under complex working conditions.

[0018] In Example 2, the sum of the thicknesses of the upper rigid PVC surface layer and the lower rigid PVC surface layer is equal to the thickness of the intermediate foamed core layer.

[0019] In this embodiment, preferably, the sum of the thicknesses of the upper and lower rigid PVC surface layers is equal to the thickness of the middle foamed core layer (thickness ratio is 1:1).

[0020] The co-extrusion composite process for preparing the spiral wound pipe repair profile in this embodiment achieves a precise balance of structural strength, impact resistance, noise reduction, and lightweight by designing the upper and lower rigid PVC surface layers and the middle foamed core layer with equal thickness in a 1:1 ratio, thus meeting the needs of most pipe repair projects.

[0021] In Example 3, in step 200, the first preset condition includes mixing for 5-8 minutes at 1500 r / min and 115-125°C, and then cooling to below 45°C at 150 r / min; the second preset condition includes mixing for 3-5 minutes at 600 r / min and 80-90°C; the third preset condition is the same as the first preset condition.

[0022] In this embodiment, preferably, the first preset condition is to mix for 5-8 minutes at 1500 r / min (rpm) and 115℃-125℃, and then cool to below 45℃ at 150 r / min (rpm); the second preset condition is to mix for 3-5 minutes at 600 r / min (rpm) and 80℃-90℃; the third preset condition is the same as the first preset condition.

[0023] The co-extrusion composite process for preparing the spiral-wound pipe repair profile in this embodiment employs differentiated mixing parameters for the three layers of raw materials. This ensures that the components of the upper and lower rigid PVC surface layers are fully and uniformly dispersed, preventing agglomeration and guaranteeing high plasticization quality and mechanical properties of the surface material. Simultaneously, it effectively protects the activity of the foaming agent in the middle foam core layer, preventing premature decomposition and failure, ensuring uniform foaming and fine cell structure, and guaranteeing excellent impact resistance and noise reduction performance of the middle foam core layer. Using the same mixing conditions for both the upper and lower surface layers ensures a symmetrical profile structure and a simple process. These differentiated mixing conditions provide a high-quality, stable three-layer material base for subsequent three-layer co-extrusion molding.

[0024] In Example 4, in step 300, the extrusion temperature of both the first layer material and the third layer material is 165℃-185℃.

[0025] Among them, the extrusion temperature refers to the heating temperature range set in the heating and plasticizing sections of the extruder, which is used to heat, melt, and plasticize the solid dry mixture to form a uniform and flowable melt.

[0026] In this embodiment, preferably, the extrusion temperature of both the first layer material and the third layer material is 165℃-185℃.

[0027] The co-extrusion composite process for preparing the spiral wound pipe repair profile in this embodiment, through precise control of the extrusion temperature of the first and third layer materials, ensures that the upper and lower rigid PVC surface layers are fully plasticized, melted uniformly, and flow stably, avoiding insufficient plasticization or overheating degradation; it also ensures that the upper and lower surface layers have uniform thickness, smooth surface, accurate dimensions, and tight interlayer bonding, thereby improving the overall high strength and good structural stability of the profile, simplifying process control, and improving production stability and yield.

[0028] In Example 5, in step 300, the extrusion temperature of the second layer material is 155℃-175℃.

[0029] In this embodiment, preferably, the extrusion temperature of the second layer material is 155℃-175℃.

[0030] The co-extrusion composite process for preparing the spiral wound pipe repair profile in this embodiment, through precise control of the extrusion temperature of the second layer material, avoids premature decomposition and failure of the foaming agent, retains the activity of the foaming agent, and ensures that the dry mixture of the middle foam core layer is gently plasticized, melted uniformly, and has controllable flow, thus ensuring a stable foaming ratio and achieving uniform decomposition of the foaming agent to form a fine and uniform cell structure. It also ensures a strong bond between layers, avoids overheating and collapse or under-foaming of the middle foam core layer, improves the overall high impact resistance and excellent noise reduction effect of the profile, simplifies process control, and improves production stability and the lightweight level of the finished product.

[0031] In Example 6, in step 300, the temperature of the three-layer co-extrusion die is 160℃-175℃.

[0032] In this embodiment, preferably, the temperature of the three-layer co-extrusion die is 160℃-175℃.

[0033] The co-extrusion composite process for preparing spiral-wound pipe repair profiles in this embodiment, through precise control of the temperature of the three-layer co-extrusion die, ensures both consistent fluidity of the three melt layers, allowing each melt layer to uniformly fill the die channels and form a profile with precise dimensions and a smooth surface; it also ensures temperature matching of each melt layer, resulting in tight adhesion at the interface melting points and strong interlayer bonding, preventing delamination. This die temperature control avoids surface roughness and dimensional deviations caused by rapid cooling of the upper and lower rigid PVC surface layers, ensuring a regular profile cross-section, precise dimensions, and good straightness. Simultaneously, it prevents technical defects such as uneven cell formation, collapse, or under-foaming in the intermediate foamed core layer due to excessive temperature differences. This allows the profile to achieve high strength, high impact resistance, and noise reduction performance, effectively improving the overall quality and production stability of the profile.

[0034] In Example 7, step 400, the shaping process of the extruded profile includes a vacuum shaping process, wherein the negative pressure of the vacuum shaping process is 0.03 MPa-0.05 MPa.

[0035] Vacuum shaping refers to a process that uses vacuum to create negative pressure, causing the outer wall of the molten profile just extruded from the mold to adhere to the inner wall of the shaping mold, thereby quickly fixing the cross-sectional shape and size of the profile.

[0036] In this embodiment, preferably, the extruded profile is shaped by vacuum shaping, with a negative pressure of 0.03 MPa-0.05 MPa.

[0037] The co-extrusion composite process for preparing spiral wound pipe repair profiles in this embodiment, through precise control of the shaping treatment method and specific process parameter range of the extruded profile, can provide sufficient adsorption force to enable the extruded profile to quickly and tightly adhere to the inner wall of the shaping die, ensuring a regular cross-section, accurate dimensions, and a smooth surface; at the same time, it can avoid excessive negative pressure that could lead to surface collapse of the profile, excessive shrinkage of the foam layer, or deformation of the foam cells, effectively maintaining the stability of the three-layer composite structure, ensuring the overall dimensional accuracy and appearance quality of the profile, and effectively improving the overall quality and production qualification rate of the profile.

[0038] In Example 8, step 400 involves cooling the extruded profile by controlling it to undergo a first stage of water cooling, a second stage of water cooling, and a third stage of water cooling. The temperature range of the first stage of water cooling is 18℃-22℃, the temperature range of the second stage of water cooling is 14℃-18℃, and the temperature range of the third stage of water cooling is 10℃-14℃.

[0039] In this embodiment, preferably, the cooling treatment of the extruded profile is to control the extruded profile to undergo a first stage of water cooling treatment, a second stage of water cooling treatment, and a third stage of water cooling treatment in sequence. The temperature range of the first stage of water cooling treatment is 18℃-22℃, the temperature range of the second stage of water cooling treatment is 14℃-18℃, and the temperature range of the third stage of water cooling treatment is 10℃-14℃.

[0040] The co-extrusion composite process for preparing the spiral-wound pipe repair profile in this embodiment employs a three-stage gradient water cooling treatment from high to low: the first stage uses a higher water temperature to moderate the rapid cooling of the profile, avoiding warping and cracking caused by the rapid shrinkage of the rigid PVC surface layer, and protecting the foam core layer cells from sudden cooling collapse; the second stage uses a transitional cooling to continuously dissipate internal heat and stabilize the cell formation structure; the third stage uses low-temperature water cooling to thoroughly cool the profile, completely releasing the internal stress and locking the profile cross-sectional dimensions. Gradient cooling can balance the cooling and shrinkage rate of the three-layer co-extruded composite profile, reducing profile deformation and bending defects, ensuring profile straightness and dimensional accuracy, improving the overall mechanical properties of the profile, and reducing the production scrap rate.

[0041] In Example 9, the profile traction speed of the first, second, and third water cooling treatments is 1.5m / min-3.0m / min, the length of the cooling section is 0.5m, and the total cooling time is 10s-25s.

[0042] Among them, the profile traction speed refers to the linear speed at which the traction equipment (such as a tracked traction machine) pulls the extruded profile through the three water-cooling sections at a constant speed during the cooling process, and the unit is m / min (meters per minute).

[0043] In this embodiment, preferably, the profile traction speed for the first, second, and third water cooling treatments is 1.5m / min-3.0m / min, the cooling section length is 0.5m, and the total cooling time is 10s-25s.

[0044] The co-extrusion composite process for preparing spiral-wound pipe repair profiles in this embodiment achieves precise control over the cooling treatment method and specific process parameter range of the extruded profile. A constant traction speed ensures uniform and controllable heat dissipation time within the three-stage gradient water cooling sections, preventing excessively long or short local cooling times. Simultaneous cooling and shrinkage of the upper and lower rigid PVC surface layers and the middle foamed core layer, with matched shrinkage rates, effectively suppresses profile twisting and warping, ensuring profile straightness and dimensional accuracy, and balancing profile forming quality and production pass rate. A fixed cooling section length, combined with a total cooling time range, guarantees sufficient cooling time for the profile to release internal stress and solidify the cell structure, without reducing production line processing efficiency due to excessive cooling time.

[0045] In Example 10, a spiral wound pipe repair profile is provided, which is prepared using the co-extrusion composite process of the spiral wound pipe repair profile described in any one of Examples 1 to 9 above. To avoid repetition, further details are omitted here.

[0046] In this embodiment, the spiral wound pipe repair profile includes a profile base plate, which includes an upper rigid PVC surface layer, an intermediate foamed core layer, and a lower rigid PVC surface layer. The profile base plate is also provided with additional structures such as T-shaped longitudinal reinforcing ribs, end lips, sealing strips, male and female locking buckles, and all additional structures are made of solid rigid PVC.

[0047] In this embodiment, as Figure 2 The image shown is a schematic diagram of the cross-sectional structure of a spirally wound pipe repair profile; as shown... Figure 3 The image shown is a structural schematic diagram of the base plate of a spiral-wound pipe repair profile; as shown... Figure 4 The diagram shows the cell structure of the middle foam core layer of a spirally wound pipe repair profile. A1 is the upper rigid PVC surface layer, B is the middle foam core layer, and A2 is the lower rigid PVC surface layer. A1, B, and A2 together constitute the base plate of the pipe repair profile. w e is the total thickness of the profile base plate (in mm), e0 is the maximum height of the profile (in mm), e R1 is the height of the male lock (in mm); w is the effective unfolded width of the profile cross-section (excluding the buckle, in mm); w1 is the width of the profile cross-section (in mm); 1 and 3 are both male locks, 5 and 6 are both female locks; 2 is the end lip; 4 is the sealing strip.

[0048] In Example 11, when the total thickness of the profile base plate is 3mm, the thickness of the upper and lower rigid PVC surface layers is 0.75mm, the thickness of the middle foam core layer is 1.5mm, the density of the middle foam core layer is 0.81g / cm³, and the foaming ratio is 2.1 times.

[0049] The tensile yield strength of the profile base plate was tested according to the testing standard GB / T1040.2-2022, and the measured tensile yield strength was 38 MPa, which is 95% of that of a pure solid rigid PVC profile of the same specification. The impact energy absorption capacity of the profile base plate was tested according to the testing standard GB / T1043.1, and the measured notched impact strength of a simply supported beam at 23℃ was 50.6 kJ / m², which is 2.1 times that of a pure solid rigid PVC profile of the same specification. The sound pressure level of the profile base plate was tested according to the testing standard GB / T3222.2-2022, and the measured sound pressure level was 62 dB(A), which is 9.2 dB(A) lower than that of a pure solid rigid PVC profile of the same specification.

[0050] In Example 12, when the total thickness of the profile base plate is 3mm, the thickness of the upper and lower rigid PVC surface layers is 0.60mm, the thickness of the middle foam core layer is 1.8mm, and the density of the middle foam core layer is 0.71g / cm³.

[0051] The tensile yield strength of the profile base plate was tested according to the testing standard GB / T1040.2-2022, and the measured tensile yield strength was 36 MPa, which is 90% of that of a pure solid rigid PVC profile of the same specification. The impact energy absorption capacity of the profile base plate was tested according to the testing standard GB / T1043.1, and the measured notched impact strength of a simply supported beam at 23℃ was 60 kJ / m², which is 2.49 times that of a pure solid rigid PVC profile of the same specification. The sound pressure level of the profile base plate was tested according to the testing standard GB / T3222.2-2022, and the measured sound pressure level was 60 dB(A), which is 10.5 dB(A) lower than that of a pure solid rigid PVC profile of the same specification.

[0052] In the comparative example, the total thickness of the solid rigid PVC profile base plate is 3mm.

[0053] The tensile yield strength of the solid rigid PVC profile base plate was tested according to the testing standard GB / T1040.2-2022, and the measured tensile yield strength was 40 MPa. The impact energy absorption capacity of the solid rigid PVC profile base plate was tested according to the testing standard GB / T1043.1, and the measured notched impact strength of the simply supported beam at 23℃ was 24.1 kJ / m². The sound pressure level of the profile base plate was tested according to the testing standard GB / T3222.2-2022, and the measured sound pressure level was 71.2 dB(A).

[0054] Compared with Example 11, the notched impact strength of the simply supported beam of the spiral wound pipe repair profile of the present invention at 23°C is increased by 111%, the tensile yield strength is reduced by 5%, and the sound pressure level is reduced by 9.2 dB(A), which proves that the spiral wound pipe repair profile of the present invention has significant effects in improving impact resistance, maintaining yield strength, and reducing noise.

[0055] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0056] While specific embodiments of the invention have been described in detail by way of example, those skilled in the art should understand that the examples are for illustrative purposes only and not intended to limit the scope of the invention. Those skilled in the art should also understand that various modifications can be made to the embodiments without departing from the scope and spirit of the invention. The scope of this invention is defined by the appended claims.

Claims

1. A method for preparing a helical wound pipe repair profile using a co-extrusion composite process, characterized in that, The co-extrusion composite process for preparing the spiral wound pipe repair profile includes: Step 100: Obtain the raw materials for the upper rigid PVC surface layer of the pipe repair profile, the raw materials for the middle foamed core layer of the pipe repair profile, and the raw materials for the lower rigid PVC surface layer of the pipe repair profile. Step 200: The raw materials of the upper rigid PVC surface layer are controlled to be mixed according to the first preset conditions, the raw materials of the middle foamed core layer are controlled to be mixed according to the second preset conditions, and the raw materials of the lower rigid PVC surface layer are controlled to be mixed according to the third preset conditions, to obtain the first layer material for forming the upper rigid PVC surface layer, the second layer material for forming the middle foamed core layer, and the third layer material for forming the lower rigid PVC surface layer. Step 300: Using three extruders, the first layer material, the second layer material and the third layer material are plasticized and then simultaneously extruded into a three-layer co-extrusion die for molding to obtain an extruded profile with a three-layer co-extrusion composite structure. Step 400: The extruded profile is subjected to shaping and cooling treatment to obtain the spiral wound pipe repair profile.

2. The method for preparing the spiral wound pipe repair profile by co-extrusion composite process according to claim 1, characterized in that, The sum of the thicknesses of the upper rigid PVC surface layer and the lower rigid PVC surface layer is equal to the thickness of the intermediate foamed core layer.

3. The method for preparing the spiral wound pipe repair profile by co-extrusion composite process according to claim 1, characterized in that, In step 200, the first preset condition includes mixing for 5-8 minutes at 1500 r / min and 115-125°C, and then cooling to below 45°C at 150 r / min; the second preset condition includes mixing for 3-5 minutes at 600 r / min and 80-90°C; the third preset condition is the same as the first preset condition.

4. The method for preparing the spiral wound pipe repair profile by co-extrusion composite process according to claim 1, characterized in that, In step 300, the extrusion temperature of both the first layer material and the third layer material is 165℃-185℃.

5. The method for preparing the spiral wound pipe repair profile by co-extrusion composite process according to claim 1, characterized in that, In step 300, the extrusion temperature of the second layer material is 155℃-175℃.

6. The method for preparing the spiral wound pipe repair profile by co-extrusion composite process according to claim 1, characterized in that, In step 300, the temperature of the three-layer co-extrusion die is 160℃-175℃.

7. The method for preparing the spiral wound pipe repair profile by co-extrusion composite process according to claim 1, characterized in that, In step 400, the extruded profile is shaped, including a vacuum shaping process, wherein the negative pressure of the vacuum shaping process is 0.03 MPa to 0.05 MPa.

8. The method for preparing the spiral wound pipe repair profile by co-extrusion composite process according to claim 1, characterized in that, In step 400, cooling the extruded profile includes controlling the extruded profile to undergo a first stage of water cooling, a second stage of water cooling, and a third stage of water cooling in sequence. The temperature range of the first stage of water cooling is 18℃-22℃, the temperature range of the second stage of water cooling is 14℃-18℃, and the temperature range of the third stage of water cooling is 10℃-14℃.

9. The method for preparing the spiral wound pipe repair profile by co-extrusion composite process according to claim 7, characterized in that, The profile traction speed for the first, second, and third water cooling stages is 1.5 m / min to 3.0 m / min, the cooling section length is 0.5 m, and the total cooling time is 10 s to 25 s.

10. A spiral-wound pipe repair profile, characterized in that, It is prepared using the co-extrusion composite process of the spiral wound pipe repair profile as described in any one of claims 1-9.

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