A barrier-type multilayer composite pipe and its preparation process

Abstract

The present invention relates to the technical field of composite pipes, and in particular to a barrier-type multilayer composite pipe and a preparation process thereof, the process comprising: using an extruder and a tractor to co-extrude a first PE inner core layer, a first maleic anhydride grafted adhesive layer, an EVOH barrier layer, a second maleic anhydride grafted adhesive layer and a second PE inner core layer to output a barrier inner layer; spirally winding industrial polyester filaments to output a reinforcement layer, assembling the barrier inner layer, the isolation layer, the reinforcement layer and an outer protective layer and performing heat treatment to output a multilayer composite pipe; determining the preparation stability of the multilayer composite pipe based on the variance of the extrusion speed of the multilayer composite pipe; if the preparation stability does not meet the requirements, adjusting the speed of the screw in the extruder; if the processing reliability does not meet the requirements, adjusting the traction power of the tractor. The present invention improves the preparation stability of the multilayer composite pipe.

Description

Technical Field

[0001] The present invention relates to the technical field of composite pipes, and in particular to a barrier-type multi-layer composite pipe and a preparation process thereof. Background Art

[0002] In the existing technology, in the field of pipeline industry, with the continuous improvement of pipeline performance requirements, the application of barrier-type multi-layer composite pipelines has become more and more extensive. For example, in industries such as chemical raw material transportation, food and beverage preservation transportation, and gas transportation, there are strict standards for the barrier performance, mechanical strength and durability of pipelines. Traditional single-layer pipelines can no longer meet these complex requirements, and multi-layer composite pipelines have emerged. Through the combination of different material layers, they integrate the advantages of each layer of materials, thus having better comprehensive performance.

[0003] Chinese Patent Publication No.: CN117386893A discloses a multi-layer composite antibacterial PE water supply pipe and its preparation process, including the following steps: S1. Material preparation: Ensure that the required raw materials are prepared according to the formula, and mix and weigh various raw materials in accurate proportions, including the base materials of the inner layer material, the middle layer material and the outer layer material, as well as other additives and reinforcing materials that need to be added. S2. Material mixing: Mix the raw materials of each layer of material separately. To ensure the uniformity of mixing, use a closed mixer to mix so that the components of each layer of material are evenly dispersed, and obtain a premix, which is processed into a suitable shape to obtain an inner layer masterbatch, a middle layer masterbatch and an outer layer masterbatch. S3. Melting: Heat and melt each layer of masterbatch through a twin-screw extruder to make it a hot-melt flow state, and further stir to ensure that the material is fully and evenly melted; S4. Co-extrusion: Through three-layer co-extrusion, the hot-melt masterbatch of each layer is extruded at the same time to ensure that the inner layer, middle layer and outer layer materials form a tight bond. S5. Cooling and molding: The extruded hot-melt material is cooled through a cooling device to make it solidify and shape quickly. S6. Cutting and shaping: According to the predetermined size requirements, use appropriate cutting tools to cut the pipe to ensure that the length and shape of the pipe meet the requirements. S7. Deburring and trimming: After cutting, the cut part of the pipe is deburred and trimmed to ensure that the cut is smooth and burr-free and meets the required surface quality requirements. It can be seen that the multi-layer composite antibacterial PE water supply pipe and its preparation process have the problem that the friction between the screw and the material will cause the surface wear of the screw, which affects the transportation and plasticization process of the material in the screw groove, resulting in incomplete plasticization of the material and thus causing the preparation stability of the multi-layer composite pipe to decrease. Summary of the invention

[0004] To this end, the present invention provides a barrier-type multi-layer composite pipe and a preparation process thereof, so as to overcome the problem in the prior art that the friction between the screw and the material causes wear on the screw surface, thereby affecting the conveying and plasticizing process of the material in the screw groove, resulting in incomplete plasticization of the material and thus causing a decrease in the preparation stability of the multi-layer composite pipe.

[0005] To achieve the above-mentioned purpose, the present invention provides a preparation process of a barrier-type multilayer composite pipe, comprising: using an extruder and a traction machine to co-extrude a first PE inner core layer, a first maleic anhydride grafted adhesive layer, an EVOH barrier layer, a second maleic anhydride grafted adhesive layer and a second PE inner core layer to output a barrier inner layer, and coating an aluminum foil material on the surface of the barrier inner layer to form an isolation layer; spirally winding industrial polyester filaments to output a reinforcement layer, assembling the barrier inner layer, the isolation layer, the reinforcement layer and an outer protective layer and performing heat treatment to output a multilayer composite pipe; obtaining the extrusion speed of a plurality of unit lengths of the multilayer composite pipe; determining the preparation stability of the multilayer composite pipe based on the variance of the extrusion speed of the multilayer composite pipe; if the preparation stability does not meet the requirements, adjusting the rotation speed of the screw in the extruder, or determining the processing reliability of the multilayer composite pipe based on the average length of the multilayer composite pipe; if the processing reliability does not meet the requirements, adjusting the traction power of the traction machine, or adjusting the supply rate of the coolant in the extruder based on the temperature rise rate of the radiator surface in the extruder.

[0006] Further, determining the preparation stability of the multi-layer composite pipe includes:

[0007] comparing the variance of the extrusion speed of the multi-layer composite pipe with a preset first variance;

[0008] If the variance of the extrusion speed of the multi-layer composite pipe is greater than the preset first variance, it is determined that the preparation stability of the multi-layer composite pipe does not meet the requirements.

[0009] Further, determining the processing reliability of the multi-layer composite pipe includes:

[0010] Comparing the variance of the extrusion speed of the multi-layer composite pipe with the preset first variance and the preset second variance respectively;

[0011] If the variance of the extrusion speed of the multi-layer composite pipe is greater than the preset first variance and less than or equal to the preset second variance, it is preliminarily determined that the processing reliability of the multi-layer composite pipe does not meet the requirements, and the processing reliability of the multi-layer composite pipe is determined based on the average length of the multi-layer composite pipe.

[0012] Further, the rotation speed of the screw in the extruder is adjusted, including:

[0013] comparing the variance of the extrusion speed of the multi-layer composite pipe with the preset second variance;

[0014] If the variance of the extrusion speed of the multi-layer composite pipe is greater than a preset second variance, the rotation speed of the screw in the extruder is reduced.

[0015] Furthermore, the reduction range of the rotation speed of the screw in the extruder is determined by the difference between the variance of the extrusion speed of the multi-layer composite pipe and a preset second variance.

[0016] Furthermore, the traction power of the traction machine is adjusted, including:

[0017] comparing the average length of the multilayer composite pipe with a preset first length and a preset second length respectively;

[0018] If the average length of the multi-layer composite pipe is greater than the preset first length, it is determined that the processing reliability of the multi-layer composite pipe does not meet the requirements;

[0019] If the average length of the multi-layer composite pipe is greater than the preset first length and less than or equal to the preset second length, increasing the traction power of the traction machine;

[0020] If the average length of the multilayer composite pipe is greater than the preset second length, it is preliminarily determined that the environmental stability of the preparation of the multilayer composite pipe does not meet the requirements, and the environmental stability of the preparation of the multilayer composite pipe is determined based on the temperature rise rate of the radiator surface in the extruder.

[0021] Furthermore, the increase range of the traction power of the traction machine is determined by the difference between the average length of the multi-layer composite pipe and the preset first length.

[0022] Further, the supply rate of the coolant in the extruder is adjusted, comprising:

[0023] Compare the temperature increase rate of the heat sink surface in the extruder with the preset increase rate;

[0024] If the temperature increase rate of the radiator surface in the extruder is greater than the preset increase rate, it is determined that the environmental stability of the multi-layer composite pipe preparation does not meet the requirements, and the supply rate of the coolant in the extruder is increased.

[0025] Furthermore, the increase range of the supply rate of the coolant in the extruder is determined by the difference between the temperature increase rate of the surface of the radiator in the extruder and a preset increase rate.

[0026] The present invention also provides a barrier-type multilayer composite pipe, comprising: a first PE inner core layer, a first maleic anhydride grafted adhesive layer, an EVOH barrier layer, a second maleic anhydride grafted adhesive layer, a second PE inner core layer, an aluminum foil isolation layer, a reinforcement layer and an outer protective layer.

[0027] Compared with the prior art, the beneficial effect of the present invention lies in that the process of the present invention adjusts the rotation speed of the screw in the extruder according to the variance of the extrusion speed of the multi-layer composite pipe. Due to long-term use, the friction between the screw and the material will cause wear on the screw surface. The depth and width of the screw groove after wear change, which affects the transportation and plasticization process of the material in the screw groove, resulting in a shortened residence time of the material in the extruder and incomplete plasticization. By reducing the rotation speed of the screw in the extruder, the residence time of the material in the screw can be extended, allowing the material to have more time to be plasticized in the screw groove, reducing the uneven extrusion caused by too fast flow rate, and adjusting the traction power of the traction machine according to the average length of the multi-layer composite pipe. Since the belt in the traction equipment will be damaged after long-term use, Aging and elongation lead to unstable friction between the belt and the pulley, which changes the transmission ratio and causes fluctuations in the traction speed. By increasing the traction power of the traction machine, more power can be provided for the traction equipment to overcome the effects of reduced friction and adverse changes in the transmission ratio. The supply rate of the coolant in the extruder is adjusted according to the temperature increase rate of the radiator surface in the extruder. Since the radiator of the extruder may be blocked by impurities such as dust and fiber, these impurities will cover the surface of the heat sink and hinder the transfer of heat. By increasing the supply rate of the coolant in the extruder, the flow rate of the coolant in the radiator can be increased, which can compensate for the insufficient heat dissipation caused by the blockage to a certain extent, thereby helping to reduce the temperature of the radiator and improving the preparation stability of the multi-layer composite pipe.

[0028] Furthermore, the process of the present invention adjusts the rotation speed of the screw in the extruder by setting a preset first variance and a preset second variance. Due to long-term use, the friction between the screw and the material will cause wear on the screw surface. The depth and width of the screw groove after wear change, which affects the conveying and plasticizing process of the material in the screw groove, resulting in a shortened residence time of the material in the extruder and incomplete plasticization. By reducing the rotation speed of the screw in the extruder, the residence time of the material in the screw can be extended, allowing the material to have more time to be plasticized in the screw groove, reducing the uneven extrusion caused by excessive flow rate, and further improving the preparation stability of the multi-layer composite pipe.

[0029] Furthermore, the process described in the present invention adjusts the traction power of the traction machine by setting a preset first length and a preset second length. Since the belt in the traction equipment will age and stretch after long-term use, the friction between the belt and the pulley will be unstable, causing the transmission ratio to change, and then causing the traction speed to fluctuate. By increasing the traction power of the traction machine, more power can be provided to the traction equipment to overcome the effects of reduced friction and adverse changes in the transmission ratio, thereby further improving the preparation stability of the multi-layer composite pipe.

[0030] Furthermore, the process of the present invention adjusts the supply rate of the coolant in the extruder by setting a preset increase rate. Since the radiator of the extruder may be clogged with impurities such as dust and fibers, these impurities will cover the surface of the heat sink and hinder the heat transfer. By increasing the supply rate of the coolant in the extruder, the flow rate of the coolant in the radiator can be increased, which can compensate for the insufficient heat dissipation caused by the blockage to a certain extent, thereby helping to reduce the temperature of the radiator and further improving the preparation stability of the multi-layer composite pipe. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is an overall flow chart of the preparation process of the barrier-type multi-layer composite pipe according to an embodiment of the present invention;

[0032] Figure 2 This is a cross-sectional structural diagram of a barrier-type multi-layer composite pipe according to an embodiment of the present invention;

[0033] Figure 3 It is a logic flow chart of the preparation process of the barrier-type multi-layer composite pipe according to an embodiment of the present invention;

[0034] Figure 4 A specific flow chart of the process of adjusting the speed of the screw in the extruder in the preparation process of the barrier-type multi-layer composite pipe according to an embodiment of the present invention;

[0035] The figure numbers are as follows: 1-first PE inner core layer, 2-first maleic anhydride grafted adhesive layer, 3-EVOH barrier layer, 4-second maleic anhydride grafted adhesive layer, 5-second PE inner core layer, 6-isolation layer, 7-reinforcement layer, 8-outer protective layer. DETAILED DESCRIPTION

[0036] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0037] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0038] It should be noted that, in the description of the present invention, terms such as "up", "down", "left", "right", "inside" and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings. This is merely for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0039] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0040] See also Figure 1 , Figure 2 , Figure 3 as well as Figure 4 As shown, they are respectively an overall flow chart of the barrier-type multilayer composite pipe and its preparation process according to an embodiment of the present invention, a cross-sectional structure diagram, a logic flow chart, and a specific flow chart of the process of adjusting the speed of the screw in the extruder. A preparation process of a barrier-type multilayer composite pipe according to the present invention comprises:

[0041] Step S1, using an extruder and a tractor to co-extrude the first PE inner core layer, the first maleic anhydride grafted adhesive layer, the EVOH barrier layer, the second maleic anhydride grafted adhesive layer and the second PE inner core layer to output a barrier inner layer, and coating an aluminum foil material on the surface of the barrier inner layer to form an isolation layer;

[0042] Step S2, spirally winding the industrial polyester filament to output a reinforcement layer, assembling the barrier inner layer, the isolation layer, the reinforcement layer and the outer protective layer and performing heat treatment to output a multi-layer composite pipe;

[0043] Step S3, obtaining the extrusion speed of a plurality of unit lengths of the multilayer composite pipe;

[0044] Step S4, determining the preparation stability of the multi-layer composite pipe based on the variance of the extrusion speed of the multi-layer composite pipe;

[0045] Step S5, if the preparation stability does not meet the requirements, adjusting the speed of the screw in the extruder, or determining the processing reliability of the multi-layer composite pipe based on the average length of the multi-layer composite pipe;

[0046] Step S6: if the processing reliability does not meet the requirement, the traction power of the traction machine is adjusted, or the supply rate of the coolant in the extruder is adjusted based on the temperature increase rate of the radiator surface in the extruder.

[0047] Specifically, the heat treatment is an annealing treatment, and the treatment process is to use an annealing furnace to heat the multilayer composite pipe at a heating rate of 5-10°C / min, maintain it for a period of time when the heating reaches the annealing temperature of the corresponding material, and then cool the multilayer composite pipe at a cooling rate of 3-5°C / min. When the temperature cools to room temperature, take out the multilayer composite pipe.

[0048] In implementation, the process of the present invention adjusts the speed of the screw in the extruder according to the variance of the extrusion speed of the multi-layer composite pipe. Due to long-term use, the friction between the screw and the material will cause wear on the screw surface. The depth and width of the screw groove after wear will change, which will affect the transportation and plasticization process of the material in the screw groove, resulting in a shortened residence time of the material in the extruder and incomplete plasticization. By reducing the speed of the screw in the extruder, the residence time of the material in the screw can be extended, allowing the material to have more time to be plasticized in the screw groove, reducing the uneven extrusion caused by too fast a flow rate. The traction power of the traction machine is adjusted according to the average length of the multi-layer composite pipe. Since the belt in the traction equipment will age and elongate after long-term use, the The friction between the belt and the pulley is unstable, which causes the transmission ratio to change, and then causes the traction speed to fluctuate. By increasing the traction power of the traction machine, more power can be provided for the traction equipment to overcome the effects of reduced friction and adverse changes in the transmission ratio. The supply rate of the coolant in the extruder is adjusted according to the temperature increase rate of the radiator surface in the extruder. Since the radiator of the extruder may be blocked by impurities such as dust and fiber, these impurities will cover the surface of the heat sink and hinder the transfer of heat. By increasing the supply rate of the coolant in the extruder, the flow rate of the coolant in the radiator can be increased, which can compensate for the insufficient heat dissipation caused by the blockage to a certain extent, thereby helping to reduce the temperature of the radiator and improving the preparation stability of the multi-layer composite pipe.

[0049] Specifically, determining the preparation stability of the multi-layer composite pipe includes:

[0050] comparing the variance of the extrusion speed of the multi-layer composite pipe with a preset first variance;

[0051] If the variance of the extrusion speed of the multi-layer composite pipe is greater than the preset first variance, it is determined that the preparation stability of the multi-layer composite pipe does not meet the requirements.

[0052] Specifically, determining the processing reliability of the multi-layer composite pipe includes:

[0053] Comparing the variance of the extrusion speed of the multi-layer composite pipe with the preset first variance and the preset second variance respectively;

[0054] If the variance of the extrusion speed of the multi-layer composite pipe is greater than the preset first variance and less than or equal to the preset second variance, it is preliminarily determined that the processing reliability of the multi-layer composite pipe does not meet the requirements, and the processing reliability of the multi-layer composite pipe is determined based on the average length of the multi-layer composite pipe.

[0055] It can be understood that the three intervals corresponding to the preset first variance and the preset second variance correspond to three situations respectively:

[0056] The first interval is that the variance of the extrusion speed of the multi-layer composite pipe is less than or equal to the preset first variance, and the corresponding situation is: the preparation stability of the multi-layer composite pipe meets the requirements;

[0057] The second interval is that the variance of the extrusion speed of the multilayer composite pipe is greater than the preset first variance and less than or equal to the preset second variance. The corresponding situation is that the belt in the traction equipment will age and stretch after long-term use, resulting in unstable friction between the belt and the pulley, causing the transmission ratio to change, thereby causing fluctuations in the traction speed;

[0058] The third interval is that the variance of the extrusion speed of the multi-layer composite pipe is greater than the preset second variance. The corresponding situation is: due to long-term use, the friction between the screw and the material will cause wear on the screw surface. The depth and width of the screw groove after wear will change, which will affect the transportation and plasticization process of the material in the screw groove, resulting in a shortened residence time of the material in the extruder and incomplete plasticization.

[0059] In practice, the preset first variance is generally selected in the range of [0.08 (m / min) 2 , 0.12 (m / min) 2 ], the preset second variance is generally selected in the range of [0.13 (m / min) 2 , 0.17 (m / min) 2 ].

[0060] Preferably, the preferred embodiment of the preset first variance is 0.1 (m / min) 2 The preferred embodiment of the preset second variance is 0.15 (m / min) 2 .

[0061] In implementation, the process of the present invention determines the preparation stability of the multi-layer composite pipe by setting a preset first variance and a preset second variance, thereby reducing the impact of the reduced preparation accuracy of the multi-layer composite pipe due to inaccurate determination of the preparation stability of the multi-layer composite pipe, and further improving the preparation stability of the multi-layer composite pipe.

[0062] Specifically, the rotation speed of the screw in the extruder is adjusted, including:

[0063] comparing the variance of the extrusion speed of the multi-layer composite pipe with the preset second variance;

[0064] If the variance of the extrusion speed of the multi-layer composite pipe is greater than a preset second variance, the rotation speed of the screw in the extruder is reduced.

[0065] Specifically, the reduction range of the rotation speed of the screw in the extruder is determined by the difference between the variance of the extrusion speed of the multi-layer composite pipe and a preset second variance.

[0066] Specifically, the difference between the variance of the extrusion speed of the multi-layer composite pipe and the preset second variance is 0.03 (m / min) 2 When the difference between the extrusion speed variance of the multi-layer composite pipe and the preset second variance exceeds 0.03 (m / min), the speed of the screw in the extruder is reduced to 0.9 times of the original value. 2 When the speed is reduced to 0.9 times of the original value, the speed will be increased by 0.01 (m / min) 2 , the speed of the screw in the extruder is reduced by 5r / min. For example, the difference between the variance of the extrusion speed of the multi-layer composite pipe and the preset second variance is 0.05 (m / min) 2 , the current screw speed in the extruder is 200r / min, and the reduced screw speed in the extruder is 200×0.9-5×2=170r / min.

[0067] In implementation, the process of the present invention adjusts the rotation speed of the screw in the extruder by setting a preset first variance and a preset second variance. Due to long-term use, the friction between the screw and the material will cause wear on the screw surface. The depth and width of the screw groove after wear change, which affects the conveying and plasticizing process of the material in the screw groove, resulting in a shortened residence time of the material in the extruder and incomplete plasticization. By reducing the rotation speed of the screw in the extruder, the residence time of the material in the screw can be extended, allowing the material to have more time to be plasticized in the screw groove, reducing the uneven extrusion caused by excessive flow rate, and further improving the preparation stability of the multi-layer composite pipe.

[0068] Specifically, adjusting the traction power of the traction machine includes:

[0069] comparing the average length of the multilayer composite pipe with a preset first length and a preset second length respectively;

[0070] If the average length of the multi-layer composite pipe is greater than the preset first length, it is determined that the processing reliability of the multi-layer composite pipe does not meet the requirements;

[0071] If the average length of the multi-layer composite pipe is greater than the preset first length and less than or equal to the preset second length, increasing the traction power of the traction machine;

[0072] If the average length of the multilayer composite pipe is greater than the preset second length, it is preliminarily determined that the environmental stability of the preparation of the multilayer composite pipe does not meet the requirements, and the environmental stability of the preparation of the multilayer composite pipe is determined based on the temperature rise rate of the radiator surface in the extruder.

[0073] It can be understood that the three intervals corresponding to the preset first length and the preset second length correspond to three situations respectively:

[0074] The first interval is that the average length of the multi-layer composite pipe is less than or equal to the preset first length, and the corresponding situation is: the processing reliability of the multi-layer composite pipe meets the requirements;

[0075] The second interval is when the average length of the multilayer composite pipe is greater than the preset first length and less than or equal to the preset second length. The corresponding situation is that the belt in the traction equipment will age and stretch after long-term use, resulting in unstable friction between the belt and the pulley, causing the transmission ratio to change, thereby causing fluctuations in the traction speed.

[0076] The third interval is that the average length of the multi-layer composite pipe is greater than the preset second length. The corresponding situation is: since the radiator of the extruder may be blocked by impurities such as dust and fiber, these impurities will cover the surface of the heat sink and hinder the transfer of heat.

[0077] In practice, the preset first length is generally selected from a range of [1.3m, 1.7m], and the preset second length is generally selected from a range of [1.8m, 2.2m].

[0078] Preferably, the preferred embodiment of the preset first length is 1.5 m, and the preferred embodiment of the preset second length is 2 m.

[0079] In implementation, the process of the present invention determines the processing reliability of the multi-layer composite pipe by setting a preset first length and a preset second length, thereby reducing the impact of the reduced preparation stability of the multi-layer composite pipe due to inaccurate determination of the processing reliability of the multi-layer composite pipe, and further improving the preparation stability of the multi-layer composite pipe.

[0080] Specifically, the increase range of the traction power of the traction machine is determined by the difference between the average length of the multi-layer composite pipe and the preset first length.

[0081] Specifically, when the difference between the average length of the multi-layer composite pipe and the preset first length is within 0.2m, the traction power of the traction machine increases to 1.1 times of the original value; when the difference between the average length of the multi-layer composite pipe and the preset first length exceeds 0.2m, on the basis of increasing to 1.1 times of the original value, the traction power of the traction machine increases by 50W for every 0.2m exceeding. For example, the difference between the average length of the multi-layer composite pipe and the preset first length is 0.6m, the current traction power of the traction machine is 1000W, and the increased traction power of the traction machine is 1000×1.1+50×2=1200W.

[0082] In implementation, the process of the present invention adjusts the traction power of the traction machine by setting a preset first length and a preset second length. Since the belt in the traction equipment will age and stretch after long-term use, the friction between the belt and the pulley will be unstable, causing the transmission ratio to change, and then causing the traction speed to fluctuate. By increasing the traction power of the traction machine, more power can be provided for the traction equipment to overcome the effects of reduced friction and adverse changes in the transmission ratio, thereby further improving the preparation stability of the multi-layer composite pipe.

[0083] Specifically, the supply rate of the coolant in the extruder is adjusted, comprising:

[0084] Compare the temperature increase rate of the heat sink surface in the extruder with the preset increase rate;

[0085] If the temperature increase rate of the radiator surface in the extruder is greater than the preset increase rate, it is determined that the environmental stability of the multi-layer composite pipe preparation does not meet the requirements, and the supply rate of the coolant in the extruder is increased.

[0086] It can be understood that the two intervals corresponding to the preset increase rate correspond to two situations:

[0087] The first interval is when the temperature increase rate of the heat sink surface in the extruder is less than or equal to the preset increase rate, and the corresponding situation is: the environmental stability of the multi-layer composite pipe preparation meets the requirements;

[0088] The second interval is when the temperature rise rate of the heat sink surface in the extruder is greater than the preset rise rate. The corresponding situation is: since the heat sink of the extruder may be blocked by impurities such as dust and fiber, these impurities will cover the surface of the heat sink and hinder the transfer of heat.

[0089] In practice, the preset temperature increase rate is generally selected in the range of [2°C / min, 4°C / min].

[0090] Preferably, the preset increasing rate is 3° C. / min.

[0091] In implementation, the process of the present invention determines the environmental stability of the preparation of the multi-layer composite pipe by setting a preset increase rate, thereby reducing the impact of the decreased preparation stability of the multi-layer composite pipe due to inaccurate determination of the environmental stability of the preparation of the multi-layer composite pipe, and further improving the preparation stability of the multi-layer composite pipe.

[0092] Specifically, the increase range of the supply rate of the coolant in the extruder is determined by the difference between the temperature increase rate of the surface of the radiator in the extruder and a preset increase rate.

[0093] Specifically, when the difference between the temperature rise rate of the radiator surface in the extruder and the preset rise rate is within 2°C / min, the supply rate of the coolant in the extruder is increased to 1.2 times the original rate; when the difference between the temperature rise rate of the radiator surface in the extruder and the preset rise rate exceeds 2°C / min, on the basis of increasing to 1.2 times the original rate, the supply rate of the coolant in the extruder is increased by 0.5L / min for every 1°C / min exceeding. For example, the difference between the temperature rise rate of the radiator surface in the extruder and the preset rise rate is 4°C / min, the current supply rate of the coolant in the extruder is 5L / min, and the increased supply rate of the coolant in the extruder is 5×1.2+0.5×2=7L / min.

[0094] In implementation, the process of the present invention adjusts the supply rate of the coolant in the extruder by setting a preset increase rate. Since the radiator of the extruder may be blocked by impurities such as dust and fibers, these impurities will cover the surface of the heat sink and hinder the transfer of heat. By increasing the supply rate of the coolant in the extruder, the flow rate of the coolant in the radiator can be increased, which can compensate for the insufficient heat dissipation caused by the blockage to a certain extent, thereby helping to reduce the temperature of the radiator and further improving the preparation stability of the multi-layer composite pipe.

[0095] A barrier-type multilayer composite pipe comprises: a first PE inner core layer, a first maleic anhydride grafted bonding layer, an EVOH barrier layer, a second maleic anhydride grafted bonding layer, a second PE inner core layer, an aluminum foil isolation layer, a reinforcement layer and an outer protective layer.

[0096] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A process for preparing a barrier-type multi-layer composite pipe, characterized in that: The barrier-type multilayer composite pipe comprises a first PE inner core layer, a first maleic anhydride grafted adhesive layer, an EVOH barrier layer, a second maleic anhydride grafted adhesive layer, a second PE inner core layer, an aluminum foil isolation layer, a reinforcement layer and an outer protective layer. The preparation process of the barrier-type multilayer composite pipe comprises: Co-extruding the first PE inner core layer, the first maleic anhydride grafted adhesive layer, the EVOH barrier layer, the second maleic anhydride grafted adhesive layer and the second PE inner core layer using an extruder and a tractor to output a barrier inner layer, and coating an aluminum foil material on the surface of the barrier inner layer to form an isolation layer; The industrial polyester filament is spirally wound to output a reinforcement layer, and the barrier inner layer, the isolation layer, the reinforcement layer and the outer protective layer are assembled and heat-treated to output a multi-layer composite pipe; Obtaining the extrusion speed of a multi-layer composite pipe of a certain unit length; Determining the manufacturing stability of the multi-layer composite pipe based on the variance of the extrusion speed of the multi-layer composite pipe; If the preparation stability does not meet the requirements, the speed of the screw in the extruder is adjusted, or the processing reliability of the multi-layer composite pipe is determined based on the average length of the multi-layer composite pipe; If the processing reliability does not meet the requirements, the traction power of the traction machine is adjusted, or the supply rate of the coolant in the extruder is adjusted based on the temperature increase rate of the radiator surface in the extruder; Determining the preparation stability of the multi-layer composite pipe includes: comparing the variance of the extrusion speed of the multi-layer composite pipe with a preset first variance; If the variance of the extrusion speed of the multi-layer composite pipe is greater than the preset first variance, it is determined that the preparation stability of the multi-layer composite pipe does not meet the requirements; Determining the processing reliability of the multi-layer composite pipe includes: Comparing the variance of the extrusion speed of the multi-layer composite pipe with the preset first variance and the preset second variance respectively; If the variance of the extrusion speed of the multi-layer composite pipe is greater than the preset first variance and less than or equal to the preset second variance, it is preliminarily determined that the processing reliability of the multi-layer composite pipe does not meet the requirements, and the processing reliability of the multi-layer composite pipe is determined according to the average length of the multi-layer composite pipe; The speed of the screw in the extruder is adjusted, including: comparing the variance of the extrusion speed of the multi-layer composite pipe with the preset second variance; If the variance of the extrusion speed of the multi-layer composite pipe is greater than a preset second variance, the rotation speed of the screw in the extruder is reduced.

2. The process for preparing the barrier-type multi-layer composite pipe according to claim 1, characterized in that: The reduction range of the rotation speed of the screw in the extruder is determined by the difference between the variance of the extrusion speed of the multi-layer composite pipe and a preset second variance.

3. The process for preparing the barrier-type multi-layer composite pipe according to claim 2, characterized in that: The traction power of the traction machine is adjusted, including: comparing the average length of the multilayer composite pipe with a preset first length and a preset second length respectively; If the average length of the multi-layer composite pipe is greater than the preset first length, it is determined that the processing reliability of the multi-layer composite pipe does not meet the requirements; If the average length of the multi-layer composite pipe is greater than the preset first length and less than or equal to the preset second length, increasing the traction power of the traction machine; If the average length of the multilayer composite pipe is greater than the preset second length, it is preliminarily determined that the environmental stability of the preparation of the multilayer composite pipe does not meet the requirements, and the environmental stability of the preparation of the multilayer composite pipe is determined based on the temperature rise rate of the radiator surface in the extruder.

4. The process for preparing the barrier-type multi-layer composite pipe according to claim 3, characterized in that: The increase range of the traction power of the traction machine is determined by the difference between the average length of the multi-layer composite pipe and the preset first length.

5. The process for preparing the barrier-type multi-layer composite pipe according to claim 4, characterized in that: The supply rate of the coolant in the extruder is adjusted, comprising: Compare the temperature increase rate of the heat sink surface in the extruder with the preset increase rate; If the temperature increase rate of the radiator surface in the extruder is greater than the preset increase rate, it is determined that the environmental stability of the multi-layer composite pipe preparation does not meet the requirements, and the supply rate of the coolant in the extruder is increased.

6. The process for preparing the barrier-type multi-layer composite pipe according to claim 5, characterized in that: The increase range of the supply rate of the coolant in the extruder is determined by the difference between the temperature increase rate of the surface of the radiator in the extruder and the preset increase rate.

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