Preparation method of graphene composite PE antibacterial pipe

Abstract

The invention relates to the technical field of graphene composite high polymer materials, in particular to a preparation method of a graphene composite PE antibacterial pipe, which comprises the following steps: carrying out surface modification treatment on a graphene powder raw material to form a modified graphene powder raw material; carrying out primary mixing extrusion to output a graphene composite PE master batch; adjusting the mixing rotation speed of the modified graphene powder raw material and the polyethylene particle raw material in a feeding bin; determining a mixing uniformity adjusting mode according to the variable quantity of the discharging angle; the graphene composite PE master batch and the polyethylene particle raw material are subjected to secondary mixing extrusion according to the mixing uniformity adjusting mode, and the blowing length of the pipe raw material at a discharge port of the extruder is determined according to the temperature difference quantity; determining the flow velocity of cooling water according to the vibration interval duration of the mold; the graphene composite PE pipe is formed. The antibacterial effect is improved, and the performance stability of the pipe is improved.

Description

Technical Field

[0001] The invention relates to the technical field of graphene composite polymer materials, and in particular to a method for preparing a graphene composite PE antibacterial pipe. Background Art

[0002] In the prior art, magnesium-silver ion-doped graphene is used as an antibacterial agent. It is mixed evenly with raw materials such as high-density polyethylene and activated modified ultrafine calcium carbonate powder, granulated, and then extruded into pipes through a pipe forming machine. The pipes made in this way have an antibacterial rate of more than 98% against Staphylococcus aureus, Candida albicans and Escherichia coli, and after 3 years of use, the antibacterial effect can still reach 92% to 95%. As a new type of inorganic antibacterial agent, graphene has the advantages of long antibacterial time, good effect, safety, stability, and good heat resistance.

[0003] Chinese Patent Publication No.: CN108676243A discloses a hybrid material, graphene-modified heat-resistant PE-RT pipe and its preparation method, the preparation of which includes the following steps: mixing graphene oxide dispersion and plant polyphenol solution evenly, then adding layered silicate, stirring thoroughly, heating to 50-90°C, and reacting for 6-15h; the mass ratio of graphene oxide, plant polyphenol and layered silicate is 1: (0.5-1): (0.1-1); preferably, heating to 60-80°C, and reacting for 8-10h. It can be seen that the hybrid material, graphene-modified heat-resistant PE-RT pipe and its preparation method have problems such as bacterial growth and reproduction in the pipe during long-term use, low dispersion of graphene in PE, uneven mixing during pipe preparation, and increased internal stress of the mixture due to increased mixing uniformity during extrusion, which leads to decreased toughness of the pipe. Summary of the invention

[0004] To this end, the present invention provides a method for preparing a graphene composite PE antibacterial pipe, which is used to overcome the problems in the prior art that bacteria grow and reproduce in the pipe during long-term use, the low dispersion degree of graphene in PE leads to uneven mixing when preparing the pipe, and the internal stress of the mixture increases due to increasing the uniformity of the mixing during the extrusion process, thereby causing the toughness of the pipe to decrease.

[0005] To achieve the above object, the present invention provides a method for preparing a graphene composite PE antibacterial pipe, comprising:

[0006] Performing surface modification treatment on the graphene powder raw material to form a modified graphene powder raw material;

[0007] Injecting the mixture of the modified graphene powder raw material and the polyethylene particle raw material into an extruder for one-time mixing and extrusion to output a graphene composite PE masterbatch;

[0008] Adjusting the mixing speed of the modified graphene powder raw material and the polyethylene particle raw material in the feed bin according to the input pressure of the feed port of the extruder;

[0009] Obtaining a change in the discharge angle of the graphene composite PE masterbatch;

[0010] The mixing uniformity adjustment method is determined according to the change in the discharge angle, including adjusting the feed amount within a unit feed cycle of the extruder during a mixed extrusion,

[0011] Or, adjusting the extrusion heating temperature during the secondary mixing extrusion according to the diameter of the discharge fluid formed by the graphene composite PE masterbatch at the discharge port;

[0012] Injecting the graphene composite PE masterbatch and the polyethylene granular raw material into an extruder according to the mixing uniformity adjustment method for secondary mixing and extrusion to form a pipe raw material;

[0013] Wherein, the blowing length of the discharge port of the extruder to the pipe raw material is determined according to the temperature difference of the pipe raw material during extrusion;

[0014] pouring the pipe raw material into a mold to form an initial pipe;

[0015] Determining the cooling water flow rate of a corresponding length section of the mold according to the vibration interval length of the mold;

[0016] The initial pipe is cooled and shaped according to the cooling water flow rate to form a graphene composite PE pipe.

[0017] Furthermore, the mixing uniformity adjustment method is determined according to the change in the discharge angle, including:

[0018] Comparing the change in the discharge angle with the preset first angle change;

[0019] If the change in the discharge angle is greater than the preset first angle change, it is determined that the mixing stability of the mixed material does not meet the requirements, and the mixing uniformity adjustment method is adopted;

[0020] If the variation of the discharge angle is less than or equal to the preset first angle variation, it is determined that the mixing stability of the mixed material meets the requirements.

[0021] Further, the mixing speed of the modified graphene powder raw material and the polyethylene particle raw material in the feed bin is adjusted according to the input pressure received by the feed port of the extruder, comprising:

[0022] Obtaining the input pressure of the feed port of the extruder;

[0023] comparing the input pressure with a preset pressure;

[0024] If the input pressure is greater than the preset pressure, it is determined that the raw material input stability does not meet the requirements, and the mixing speed is increased.

[0025] Furthermore, the mixing rotation speed is positively correlated with the input pressure.

[0026] Further, adjusting the feed amount within a unit feed cycle of the extruder during a mixed extrusion process comprises:

[0027] Determine the change of the discharge angle according to the discharge angle and the standard discharge angle;

[0028] The change amount of the discharge angle is further compared with the preset second angle change amount, and the preset first angle change amount is smaller than the preset second angle change amount;

[0029] If the change in the discharge angle is greater than the preset second angle change, the feed amount within the unit feed cycle is increased.

[0030] Among them, the discharge angle is the acute angle between the discharge direction of the graphene composite PE masterbatch extruded outward from the discharge port and the horizontal plane, the standard discharge angle is the lead angle of the screw blade at the discharge port of the extruder, the change in the discharge angle is the difference between the discharge angle and the standard discharge angle, and the feed amount is positively correlated with the change in the discharge angle.

[0031] Further, the extrusion heating temperature during the secondary mixed extrusion is adjusted according to the diameter of the discharge fluid formed by the graphene composite PE masterbatch at the discharge port, including:

[0032] If the variation of the discharge angle is greater than the preset first angle variation and less than or equal to the preset second angle variation, it is preliminarily determined that the mixing uniformity of the graphene composite PE masterbatch does not meet the requirements, and the diameter of the discharge fluid formed by the graphene composite PE masterbatch at the discharge port is obtained;

[0033] If the diameter of the output fluid is greater than the preset diameter, it is determined that the mixing uniformity of the graphene composite PE masterbatch does not meet the requirements, and the extrusion heating temperature during the secondary mixing extrusion is increased.

[0034] Furthermore, the extrusion heating temperature is positively correlated with the diameter of the discharge fluid.

[0035] Furthermore, the blowing length of the discharge port of the extruder to the pipe raw material is determined according to the temperature difference of the pipe raw material during extrusion, including:

[0036] Obtaining a temperature difference of the pipe raw material;

[0037] comparing the temperature difference with a preset temperature difference;

[0038] If the temperature difference is greater than the preset temperature difference, it is determined that the heat loss degree of the pipe raw material does not meet the requirements, and the blowing length of the discharge port of the extruder to the pipe raw material is increased.

[0039] Among them, the temperature difference is the difference between the temperature of the pipe raw material at the discharge port, the temperature of the pipe raw material at the feed port of the mold, and the temperature of the pipe raw material at the discharge port of the extruder, and the blowing length is positively correlated with the temperature difference.

[0040] Further, the cooling water flow rate of a corresponding length section of the mold is determined according to the vibration interval duration of the mold, including:

[0041] Obtaining the vibration interval duration of the mold when pouring the pipe raw material;

[0042] If the vibration interval duration meets the vibration interval duration condition, it is determined that the flow continuity of the pipe material does not meet the requirement, and the cooling water flow rate of the corresponding length section of the mold that meets the vibration interval duration condition is increased.

[0043] Among them, the cooling water flow rate is positively correlated with the vibration interval duration, the vibration interval duration condition is that the vibration interval duration is greater than the preset interval duration, and the position of the corresponding length segment of the mold is determined according to the flow rate of the pipe raw material and the vibration interval duration.

[0044] Furthermore, the graphene composite PE pipe comprises graphene and polyethylene.

[0045] Compared with the prior art, the beneficial effect of the present invention lies in that the method of the present invention performs surface modification treatment on the graphene powder raw material, thereby changing the dispersibility of graphene in polyethylene resin particles and increasing the interface bonding ability between graphene and polyethylene; since PE pipes are easily contaminated with bacteria during transportation after production and bacteria are very likely to breed and spread on the surface of the pipes, thereby affecting the quality and safety of the pipes, PE pipes are also easily attached by bacteria during use. Taking the water supply and drainage system as an example, biofilm is easily formed on the inner wall of the pipe, providing a suitable growth space for bacteria; although antibacterial agents can inhibit bacterial growth to a certain extent, the amount added is large, resulting in the problem of trace heavy metal residues. By adding graphene to polyethylene to improve the uniform distribution of graphene in the PE matrix, The cloth achieves efficient and lasting antibacterial effect by utilizing the two-dimensional structure and physical and chemical properties of graphene, and can avoid the problem of heavy metal residue; by setting up two mixing extrusion processes, the graphene and PE are first mixed and extruded for the first time after the graphene is surface modified to obtain the preliminary dispersed graphene composite PE masterbatch, and the mixed extrusion at this stage enhances the uniform composite performance of graphene in PE, and the masterbatch is mixed and extruded with the polyethylene raw material for the second time to obtain the final graphene composite PE antibacterial pipe. By setting up two mixing extrusions, it is ensured that the graphene can be fully and evenly dispersed in the PE matrix, thereby improving the antibacterial effect of the graphene, improving the interface bonding effect of the graphene and PE, and realizing the improvement of the performance stability of the pipe.

[0046] Furthermore, the method of the present invention performs surface modification treatment on the graphene powder raw material, and adds an active agent to react with the functional groups on the surface of the graphene, thereby forming a new chemical structure on the surface of the graphene particles, increasing the affinity of the graphene for PE, and preventing the agglomeration of the graphene particles in the PE matrix, thereby achieving an increase in the mixing effect of the pipe raw material, and further achieving an improvement in the antibacterial property of the composite material and an improvement in the performance stability of the material during long-term use by increasing the interaction between the graphene and the PE molecular chain.

[0047] Furthermore, the method of the present invention adjusts the rotation speed of the feed bin. When the injection of the mixed material is increased, the pressure at the injection port increases, which increases the shear stress generated when the mixed material is injected, reduces the fluidity of the mixed material in the extruder, and thus affects the mixing uniformity of the mixed material. By increasing the rotation speed of the feed bin, the injection speed of the mixed material can be increased, thereby reducing the input pressure, increasing the friction heat of the mixed material in the injection machine, and thereby improving the fluidity of the mixed material before injection, thereby achieving an improved degree of mixing.

[0048] Furthermore, the method of the present invention determines the feed amount of the feed bin. Due to the dispersion characteristics of graphene and polyethylene in the process of mixing and stirring the mixture in the extruder, the mixing is uneven, which leads to a deviation in the discharge angle. The mixing and stirring degree of the extruder is compensated by increasing the feed amount to increase the extrusion degree and extrusion area of ​​the mixture in the extruder, thereby achieving improved mixing uniformity.

[0049] Furthermore, the method of the present invention adjusts the extrusion heating temperature during the secondary mixed extrusion. When the graphene composite PE masterbatch is heated and expanded during the extrusion process, the dispersion characteristics of the two materials during the mixing and shearing process cause the diameter of the graphene composite PE masterbatch to exceed the range when it is extruded. By increasing the extrusion heating temperature during the secondary mixed extrusion, the interaction and fluidity between the graphene particles and the polyethylene matrix are promoted, and the interface bonding ability between them is enhanced. At the same time, the agglomeration of the graphene particles during the extrusion process is reduced through the secondary heat treatment process, thereby achieving an improvement in the mixing uniformity of the pipe raw materials and the stability of long-term use.

[0050] Furthermore, the method of the present invention adjusts the hot air blowing power at the discharge port. Due to the secondary heat treatment, the temperature of the pipe raw material increases in the extruder to generate internal stress, and the temperature changes due to the influence of the external environment during extrusion. In order to avoid cracks in the pipe during storage or mechanical processing due to internal stress, the hot air blowing power at the discharge port is increased, the temperature change degree of the pipe raw material is reduced, the temperature drop rate is slowed down, the environmental adaptability of the raw material is increased, and the mechanical properties of the pipe raw material are increased, thereby achieving an improvement in the pipe's resistance to microbial invasion.

[0051] Furthermore, the method of the present invention adjusts the cooling water flow rate. Since the pipe raw material is cut off during the process of pouring the pipe raw material into the mold, resulting in uneven structural strength and solidification position of the pipe, the solidification speed of the cut-off position is accelerated by increasing the cooling water flow rate, and the difference in structural strength of the pipe during the shaping process is reduced, thereby further achieving an improvement in the mechanical properties of the pipe. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 The whole flow chart of the preparation method of the graphene composite PE antibacterial pipe according to the embodiment of the present invention;

[0053] Figure 2 This is a flow chart of a method for adjusting mixing uniformity according to a change in a discharge angle in a method for preparing a graphene composite PE antibacterial pipe according to an embodiment of the present invention;

[0054] Figure 3 This is a flow chart of adjusting the feed amount within a unit feed cycle of an extruder during a single mixed extrusion in a method for preparing a graphene composite PE antibacterial pipe according to an embodiment of the present invention;

[0055] Figure 4 This is a flow chart of the method for preparing the graphene composite PE antibacterial pipe according to an embodiment of the present invention, which adjusts the extrusion heating temperature during secondary mixed extrusion according to the diameter of the discharge fluid formed by the graphene composite PE masterbatch at the discharge port position. DETAILED DESCRIPTION

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] See also Figure 1 , Figure 2 , Figure 3 as well as Figure 4 As shown, they are respectively an overall flow chart of the preparation method of the graphene composite PE antibacterial pipe material of the embodiment of the present invention, a flow chart of determining the mixing uniformity adjustment method according to the change in the discharge angle, a flow chart of adjusting the feed amount within the unit feed cycle of the extruder during the first mixed extrusion, and a flow chart of adjusting the extrusion heating temperature during the second mixed extrusion according to the diameter of the discharge fluid formed by the graphene composite PE masterbatch at the discharge port position. A preparation method of a graphene composite PE antibacterial pipe material of the present invention comprises:

[0061] Step S1, performing surface modification treatment on a graphene powder raw material to form a modified graphene powder raw material;

[0062] Step S2, injecting the mixture of the modified graphene powder raw material and the polyethylene particle raw material into an extruder for one mixing and extrusion to output a graphene composite PE masterbatch;

[0063] Step S3, adjusting the mixing speed of the modified graphene powder raw material and the polyethylene particle raw material in the feed bin according to the input pressure received by the feed port of the extruder;

[0064] Step S4, obtaining a change in the discharge angle of the graphene composite PE masterbatch;

[0065] Step S5, determining a mixing uniformity adjustment method according to the change in the discharge angle, including adjusting the feed amount within a unit feed cycle of the extruder during a mixed extrusion,

[0066] Or, adjusting the extrusion heating temperature during the secondary mixing extrusion according to the diameter of the discharge fluid formed by the graphene composite PE masterbatch at the discharge port;

[0067] Step S6, injecting the graphene composite PE masterbatch and the polyethylene granular raw material into an extruder according to the mixing uniformity adjustment method for secondary mixing and extrusion to form a pipe raw material;

[0068] Wherein, the blowing length of the discharge port of the extruder to the pipe raw material is determined according to the temperature difference of the pipe raw material during extrusion;

[0069] Step S7, pouring the pipe raw material into a mold to form an initial pipe;

[0070] Step S8, determining the cooling water flow rate of the corresponding length section of the mold according to the vibration interval length of the mold;

[0071] Step S9, cooling and shaping the initial pipe according to the cooling water flow rate to form a graphene composite PE pipe.

[0072] Specifically, the input pressure received by the feed port of the extruder is detected by a pressure sensor provided at the feed port of the extruder.

[0073] Specifically, the discharge angle and the diameter of the graphene composite PE masterbatch during discharge are detected by a laser rangefinder arranged in a direction parallel to the bottom surface of the discharge port of the extruder.

[0074] Specifically, a feed bin is arranged above the feed port.

[0075] Specifically, the feed amount is adjusted by the feed valve at the bottom of the feed bin.

[0076] Specifically, the mixing speed of the modified graphene powder raw material and the polyethylene particle raw material in the feed bin is adjusted by a rotating motor arranged inside the feed bin.

[0077] Specifically, the blowing length of the pipe raw material at the discharge port of the extruder is adjusted by the output power of the annular hot air blower arranged at the discharge position of the extruder.

[0078] Specifically, the extrusion heating temperature is adjusted by a heating resistor inside the melt of the injection head of the extruder.

[0079] Specifically, the general value range of the mixing mass ratio of the modified graphene powder raw material and the polyethylene particle raw material during one-time mixed extrusion is [1:10, 1:30], and the preferred embodiment of the mixing mass ratio of the modified graphene powder raw material and the polyethylene particle raw material during one-time mixed extrusion is 1:20.

[0080] Specifically, the general value range of the mixing mass ratio of the graphene composite PE masterbatch and the polyethylene granular raw material during one-time mixed extrusion is [1:50, 1:80], and the preferred embodiment of the mixing mass ratio of the graphene composite PE masterbatch and the polyethylene granular raw material during one-time mixed extrusion is 1:60.

[0081] In practice, the method of the present invention performs surface modification on the graphene powder raw material, thereby changing the dispersibility of graphene in polyethylene resin particles and increasing the interface bonding ability between graphene and polyethylene; since PE pipes are easily contaminated with bacteria during transportation after production and bacteria are very likely to breed and spread on the surface of the pipes, thereby affecting the quality and safety of the pipes, PE pipes are also easily attached by bacteria during use. Taking the water supply and drainage system as an example, biofilm is easily formed on the inner wall of the pipe, providing a suitable growth space for bacteria; although antibacterial agents can inhibit bacterial growth to a certain extent, the amount added is large, resulting in the problem of trace heavy metal residues. By adding graphene to polyethylene to improve the uniform distribution of graphene in the PE matrix, by utilizing stone The two-dimensional structure and physical and chemical properties of graphene can achieve efficient and lasting antibacterial effect, and can avoid the problem of heavy metal residue; by setting up two mixing extrusion processes, the graphene and PE are first mixed and extruded for the first time after the graphene is surface modified to obtain the preliminary dispersed graphene composite PE masterbatch, and the mixed extrusion at this stage enhances the uniform composite performance of graphene in PE, and the masterbatch is mixed and extruded with the polyethylene raw material for a second time to obtain the final graphene composite PE antibacterial pipe. By setting up two mixing extrusions, it is ensured that the graphene can be fully and evenly dispersed in the PE matrix, thereby improving the antibacterial effect of graphene, improving the interface bonding effect of graphene and PE, and achieving the improvement of the performance stability of the pipe.

[0082] Specifically, the surface of the graphene powder raw material is modified to form a modified graphene powder raw material, including:

[0083] Adding graphene powder raw materials into a dispersion solution and stirring and dispersing them to form a graphene dispersion solution;

[0084] Adding an active agent to the graphene dispersion, and stirring and heating the graphene dispersion to form a modified graphene dispersion;

[0085] The modified graphene dispersion is precipitated, filtered and dried to output a modified graphene powder raw material.

[0086] Specifically, the process of precipitating, filtering and drying the modified graphene dispersion is an existing technology well known to those skilled in the art and will not be described in detail here.

[0087] Specifically, the general range of the precipitation time for precipitating the modified graphene dispersion is [30 min, 60 min], and the preferred embodiment of the precipitation time is 40 min.

[0088] Specifically, examples of the active agent include silane coupling agent, sodium dodecylbenzene sulfonate (SDBS), cationic surfactants DTAB, TTAB, CTAB and CPB, and a preferred example of the active agent is silane coupling agent.

[0089] Specifically, the dispersion solution is deionized water, the general value range of the volume ratio of graphene in deionized water is [10%, 20%], and the preferred embodiment of the volume ratio of graphene in deionized water is 18%.

[0090] Specifically, the stirring and heating device for stirring and heating the graphene dispersion is a magnetic stirrer.

[0091] Specifically, the device for drying the modified graphene dispersion is a vacuum drying box, the general range of the drying temperature is [55°C, 65°C], and the preferred embodiment of the drying temperature is 60°C.

[0092] Specifically, the filter agent for filtering the modified graphene dispersion is deionized water, the general value range of the filtration times is [3 times, 6 times], and the preferred embodiment of the filtration times is 4 times.

[0093] Specifically, the general value range of the heating temperature for stirring and heating the graphene dispersion is [55°C, 75°C], and the preferred embodiment of the heating temperature for stirring and heating the graphene dispersion is 60°C.

[0094] Specifically, the general value range of the stirring time for stirring and heating the graphene dispersion is [50 min, 100 min], and the preferred embodiment of the heating temperature for stirring and heating the graphene dispersion is 60 min.

[0095] Specifically, the mass ratio of the graphene powder raw material to the active agent generally ranges from [1:0.1, 1:0.5], and the preferred embodiment of the mass ratio of the graphene powder raw material to the active agent is 1:0.2.

[0096] In practice, the method of the present invention performs surface modification treatment on graphene powder raw materials, and adds an active agent to react with the functional groups on the graphene surface, thereby forming a new chemical structure on the surface of the graphene particles, increasing the affinity of the graphene for PE, and preventing the agglomeration of the graphene particles in the PE matrix, thereby achieving an increase in the mixing effect of the pipe raw materials, and further achieving an improvement in the antibacterial properties of the composite material and an improvement in the performance stability of the material during long-term use by increasing the interaction between the graphene and PE molecular chains.

[0097] Specifically, the mixing uniformity adjustment method is determined according to the change in the discharge angle, including:

[0098] Comparing the change in the discharge angle with the preset first angle change;

[0099] If the change in the discharge angle is greater than the preset first angle change, it is determined that the mixing stability of the mixed material does not meet the requirements, and the mixing uniformity adjustment method is adopted;

[0100] If the variation of the discharge angle is less than or equal to the preset first angle variation, it is determined that the mixing stability of the mixed material meets the requirements.

[0101] Specifically, adjusting the mixing speed of the modified graphene powder raw material and the polyethylene particle raw material in the feed bin according to the input pressure received by the feed port of the extruder comprises:

[0102] Obtaining the input pressure of the feed port of the extruder;

[0103] comparing the input pressure with a preset pressure;

[0104] If the input pressure is greater than the preset pressure, it is determined that the raw material input stability does not meet the requirements, and the mixing speed is increased.

[0105] Specifically, the mixing speed is positively correlated with the input pressure.

[0106] Specifically, the general value range of the preset pressure is [5MPa, 5.4MPa], and the preferred embodiment of the preset pressure is 5.2MPa.

[0107] During implementation, when the difference between the input pressure and the preset pressure is within 0.1MPa, the feed bin speed increases by 5rpm. When the difference between the input pressure and the preset pressure exceeds 0.1MPa, the feed bin speed increases by 4rpm for every 0.1MPa increase. For example, if the input pressure is 5.4MPa and the current feed bin speed is 45rpm, the feed bin speed increases to 45rpm+5rpm+4rpm=54rpm.

[0108] In practice, the method of the present invention adjusts the rotation speed of the feed bin. When the injection of the mixed material is increased, the pressure at the injection port increases, resulting in an increase in the shear stress generated when the mixed material is injected, and reduces the fluidity of the mixed material in the extruder, thereby affecting the mixing uniformity of the mixed material. By increasing the rotation speed of the feed bin, the injection speed of the mixed material can be increased to reduce the input pressure, increase the friction heat of the mixed material in the injection machine, and thus improve the fluidity of the mixed material before injection, thereby achieving an improved degree of mixing.

[0109] Specifically, adjusting the feed amount within a unit feed cycle of the extruder during a mixed extrusion process includes:

[0110] Determine the change of the discharge angle according to the discharge angle and the standard discharge angle;

[0111] The change amount of the discharge angle is further compared with the preset second angle change amount, and the preset first angle change amount is smaller than the preset second angle change amount;

[0112] If the change in the discharge angle is greater than the preset second angle change, the feed amount within the unit feed cycle is increased.

[0113] Among them, the discharge angle is the acute angle between the discharge direction of the graphene composite PE masterbatch extruded outward from the discharge port and the horizontal plane, the standard discharge angle is the lead angle of the screw blade at the discharge port of the extruder, the change in the discharge angle is the difference between the discharge angle and the standard discharge angle, and the feed amount is positively correlated with the change in the discharge angle.

[0114] Specifically, the general value range of the preset second angle change is [6°, 10°], the general value range of the preset first angle change is [3°, 5°], the preferred embodiment of the preset second angle change is 8°, and the preferred embodiment of the preset first angle change is 4°.

[0115] During implementation, when the difference between the change in the discharge angle and the preset second angle change is within 1°, the feed amount increases to 1.02 times the original amount. When the difference between the change in the discharge angle and the preset second angle change exceeds 1°, the feed amount increases by 10kg / h for each 1° increase. For example, if the discharge angle is 10° and the current feed amount is 340kg / h, the feed amount increases to 340kg / h×1.02+10kg / h=356.8kg / h.

[0116] In implementation, the method of the present invention determines the feed amount of the feed bin. Due to the dispersion characteristics of graphene and polyethylene in the process of mixing and stirring the mixture in the extruder, the mixing is uneven, which leads to a deviation in the discharge angle. The mixing and stirring degree of the extruder is compensated by increasing the feed amount to increase the extrusion degree and extrusion area of ​​the mixture in the extruder, thereby achieving improved mixing uniformity.

[0117] Specifically, the extrusion heating temperature during the secondary mixed extrusion is adjusted according to the diameter of the discharge fluid formed by the graphene composite PE masterbatch at the discharge port, including:

[0118] If the variation of the discharge angle is greater than the preset first angle variation and less than or equal to the preset second angle variation, it is preliminarily determined that the mixing uniformity of the graphene composite PE masterbatch does not meet the requirements, and the diameter of the discharge fluid formed by the graphene composite PE masterbatch at the discharge port is obtained;

[0119] If the diameter of the output fluid is greater than the preset diameter, it is determined that the mixing uniformity of the graphene composite PE masterbatch does not meet the requirements, and the extrusion heating temperature during the secondary mixing extrusion is increased.

[0120] Specifically, the general value range of the preset diameter is greater than or equal to the discharge port diameter and less than or equal to 1.1 times the discharge port diameter. The preferred embodiment of the preset diameter is 1.06 times the discharge port diameter. For example, if the discharge port diameter is 20 cm, the preferred embodiment of the preset diameter is 21.2 cm.

[0121] During implementation, when the difference between the diameter and the preset diameter is within 1 cm, the extrusion heating temperature is increased by 2°C. When the difference between the diameter and the preset diameter exceeds 1 cm, the extrusion heating temperature is increased by 3°C for each 1 cm increase. For example, when the difference between the diameter and the preset diameter is 4 cm and the current extrusion heating temperature is 210°C, the extrusion heating temperature is increased to 210°C + 2°C + 3°C + 3°C = 218°C.

[0122] In practice, the method of the present invention adjusts the extrusion heating temperature during the secondary mixed extrusion. When the graphene composite PE masterbatch is heated and expanded during the extrusion process, the dispersion characteristics of the two materials during the mixing and shearing process cause the diameter of the graphene composite PE masterbatch to exceed the range when it is extruded. By increasing the extrusion heating temperature during the secondary mixed extrusion, the interaction and fluidity between the graphene particles and the polyethylene matrix are promoted, and the interface bonding ability between them is enhanced. At the same time, the agglomeration of the graphene particles during the extrusion process is reduced through the secondary heat treatment process, thereby achieving an improvement in the mixing uniformity of the pipe raw materials and the stability of long-term use.

[0123] Specifically, the blowing length of the discharge port of the extruder to the pipe raw material is determined according to the temperature difference of the pipe raw material during extrusion, including:

[0124] Obtaining a temperature difference of the pipe raw material;

[0125] comparing the temperature difference with a preset temperature difference;

[0126] If the temperature difference is greater than the preset temperature difference, it is determined that the heat loss degree of the pipe raw material does not meet the requirements, and the blowing length of the discharge port of the extruder to the pipe raw material is increased.

[0127] Among them, the temperature difference is the difference between the temperature of the pipe raw material at the discharge port, the temperature of the pipe raw material at the feed port of the mold, and the temperature of the pipe raw material at the discharge port of the extruder, and the blowing length is positively correlated with the temperature difference.

[0128] Specifically, the blowing length is the vertical length covered on the pipe raw material by the hot air blown by the annular hot air blower along the extrusion direction of the pipe raw material.

[0129] Specifically, the temperature of the pipe material at the discharge port is detected by a temperature sensor installed at the discharge port, and the temperature of the pipe material per unit height can be detected by an infrared thermometer and a thermal imaging thermometer installed on the side of the discharge port.

[0130] Specifically, the general value range of the preset temperature difference is [4°C, 8°C], and the preferred embodiment of the preset temperature difference is 5°C.

[0131] During implementation, when the difference between the temperature difference and the preset temperature difference is within 1°C, the blowing length increases by 4cm. When the difference between the temperature difference and the preset temperature difference exceeds 1°C, the blowing length increases by 2cm for every 1°C increase. For example, if the temperature difference is 8°C and the current blowing length is 20cm, the hot air blowing power increases to 20cm+4cm+2cm+2cm=28cm.

[0132] In practice, the method of the present invention adjusts the hot air blowing power at the discharge port. Due to the secondary heat treatment, the temperature of the pipe raw material rises in the extruder to generate internal stress, and the temperature changes due to the influence of the external environment during extrusion. In order to avoid cracks in the pipe during storage or mechanical processing due to internal stress, the hot air blowing power at the discharge port is increased, the temperature change degree of the pipe raw material is reduced, and the temperature drop rate is slowed down, thereby increasing the environmental adaptability of the raw material and the mechanical properties of the pipe raw material, thereby achieving an improvement in the pipe's resistance to microbial invasion.

[0133] Specifically, determining the cooling water flow rate of a corresponding length section of the mold according to the vibration interval duration of the mold includes:

[0134] Obtaining the vibration interval duration of the mold when pouring the pipe raw material;

[0135] If the vibration interval duration meets the vibration interval duration condition, it is determined that the flow continuity of the pipe material does not meet the requirement, and the cooling water flow rate of the corresponding length section of the mold that meets the vibration interval duration condition is increased.

[0136] Among them, the cooling water flow rate is positively correlated with the vibration interval duration, the vibration interval duration condition is that the vibration interval duration is greater than the preset interval duration, and the position of the corresponding length segment of the mold is determined according to the flow rate of the pipe raw material and the vibration interval duration.

[0137] Specifically, the corresponding length segment is equal to the total length of the mold minus the product of the flow rate of the pipe raw material and the time required to meet the vibration interval time condition.

[0138] Specifically, the vibration interval duration is the interval duration between vibration peaks detected by the vibration sensor.

[0139] Specifically, the vibration intensity is detected by a displacement sensor, and the location of the displacement sensor is not limited as long as the vibration intensity of the mold can be detected.

[0140] Specifically, the flow rate of the pipe material is the flow rate of the pipe material in the discharge port along the discharge direction when the pipe material is discharged from the extruder. The flow rate of the pipe material is detected by a flow meter arranged at the discharge port.

[0141] Specifically, a plurality of condensation components arranged on the mold cool and shape the initial pipe, wherein the condensation components include a condensation pipe surrounding the mold for carrying condensation water and a condensation water pump connected to the condensation pipe for conveying condensation water.

[0142] Specifically, the general value range of the preset interval time length is [0.2s, 0.4s], and the preferred embodiment of the preset interval time length is 0.3s.

[0143] During implementation, when the difference between the vibration interval and the preset interval is within 0.05s, the cooling water flow rate on the corresponding length segment of the mold increases by 0.1m / s. When the difference between the vibration interval and the preset interval exceeds 0.05s, the cooling water flow rate on the corresponding length segment of the mold increases by 0.2m / s for every 0.5s exceeded. For example, when the vibration interval is 0.4s, the cooling water flow rate is 1.2m / s, and the cooling water flow rate on the corresponding length segment of the mold increases to 1.2m / s+0.1m / s+0.2m / s=1.3m / s.

[0144] In practice, the method of the present invention adjusts the cooling water flow rate. Since the pipe raw material is cut off during the process of pouring the pipe raw material into the mold, resulting in uneven structural strength and solidification position of the pipe, the solidification speed of the cut-off position is accelerated by increasing the cooling water flow rate, the difference in structural strength of the pipe during the shaping process is reduced, and the mechanical properties of the pipe are further improved.

[0145] Specifically, the components of the graphene composite PE pipe include graphene and polyethylene.

[0146] 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 method for preparing a graphene composite PE antibacterial pipe, characterized in that: include: Performing surface modification treatment on the graphene powder raw material to form a modified graphene powder raw material; Injecting the mixture of the modified graphene powder raw material and the polyethylene particle raw material into an extruder for one-time mixing and extrusion to output a graphene composite PE masterbatch; Adjusting the mixing speed of the modified graphene powder raw material and the polyethylene particle raw material in the feed bin according to the input pressure of the feed port of the extruder; Obtaining a change in the discharge angle of the graphene composite PE masterbatch; The mixing uniformity adjustment method is determined according to the change in the discharge angle, including adjusting the feed amount within a unit feed cycle of the extruder during a mixed extrusion, Or, adjusting the extrusion heating temperature during the secondary mixing extrusion according to the diameter of the discharge fluid formed by the graphene composite PE masterbatch at the discharge port; Injecting the graphene composite PE masterbatch and the polyethylene granular raw material into an extruder according to the mixing uniformity adjustment method for secondary mixing and extrusion to form a pipe raw material; Wherein, the blowing length of the discharge port of the extruder to the pipe raw material is determined according to the temperature difference of the pipe raw material during extrusion; pouring the pipe raw material into a mold to form an initial pipe; Determining the cooling water flow rate of a corresponding length section of the mold according to the vibration interval length of the mold; The initial pipe is cooled and shaped according to the cooling water flow rate to form a graphene composite PE pipe.

2. The method for preparing the graphene composite PE antibacterial pipe according to claim 1, characterized in that: The method of adjusting the mixing uniformity according to the change in the discharge angle includes: Comparing the change in the discharge angle with the preset first angle change; If the change in the discharge angle is greater than the preset first angle change, it is determined that the mixing stability of the mixed material does not meet the requirements, and the mixing uniformity adjustment method is adopted; If the variation of the discharge angle is less than or equal to the preset first angle variation, it is determined that the mixing stability of the mixed material meets the requirements.

3. The method for preparing the graphene composite PE antibacterial pipe according to claim 2, characterized in that: The mixing speed of the modified graphene powder raw material and the polyethylene particle raw material in the feed bin is adjusted according to the input pressure of the feed port of the extruder, comprising: Obtaining the input pressure of the feed port of the extruder; comparing the input pressure with a preset pressure; If the input pressure is greater than the preset pressure, it is determined that the raw material input stability does not meet the requirements, and the mixing speed is increased.

4. The method for preparing the graphene composite PE antibacterial pipe according to claim 3, characterized in that: The mixing speed is positively correlated with the input pressure.

5. The method for preparing the graphene composite PE antibacterial pipe according to claim 4, characterized in that: Adjusting the feed amount within a unit feed cycle of the extruder during a mixed extrusion process comprises: Determine the change of the discharge angle according to the discharge angle and the standard discharge angle; The change amount of the discharge angle is further compared with the preset second angle change amount, and the preset first angle change amount is smaller than the preset second angle change amount; If the change in the discharge angle is greater than the preset second angle change, the feed amount within the unit feed cycle is increased. Among them, the discharge angle is the acute angle between the discharge direction of the graphene composite PE masterbatch extruded outward from the discharge port and the horizontal plane, the standard discharge angle is the lead angle of the screw blade at the discharge port of the extruder, the change in the discharge angle is the difference between the discharge angle and the standard discharge angle, and the feed amount is positively correlated with the change in the discharge angle.

6. The method for preparing the graphene composite PE antibacterial pipe according to claim 5, characterized in that: The extrusion heating temperature during the secondary mixed extrusion is adjusted according to the diameter of the discharge fluid formed by the graphene composite PE masterbatch at the discharge port, including: If the variation of the discharge angle is greater than the preset first angle variation and less than or equal to the preset second angle variation, it is preliminarily determined that the mixing uniformity of the graphene composite PE masterbatch does not meet the requirements, and the diameter of the discharge fluid formed by the graphene composite PE masterbatch at the discharge port is obtained; If the diameter of the output fluid is greater than the preset diameter, it is determined that the mixing uniformity of the graphene composite PE masterbatch does not meet the requirements, and the extrusion heating temperature during the secondary mixing extrusion is increased.

7. The method for preparing the graphene composite PE antibacterial pipe according to claim 6, characterized in that: The extrusion heating temperature is positively correlated with the diameter of the discharge fluid.

8. The method for preparing the graphene composite PE antibacterial pipe according to claim 7, characterized in that: The blowing length of the discharge port of the extruder to the pipe material is determined according to the temperature difference of the pipe material during extrusion, including: Obtaining a temperature difference of the pipe raw material; comparing the temperature difference with a preset temperature difference; If the temperature difference is greater than the preset temperature difference, it is determined that the heat loss degree of the pipe raw material does not meet the requirements, and the blowing length of the discharge port of the extruder to the pipe raw material is increased. Among them, the temperature difference is the difference between the temperature of the pipe raw material at the discharge port, the temperature of the pipe raw material at the feed port of the mold, and the temperature of the pipe raw material at the discharge port of the extruder, and the blowing length is positively correlated with the temperature difference.

9. The method for preparing the graphene composite PE antibacterial pipe according to claim 8, characterized in that: Determining the cooling water flow rate of a corresponding length section of the mold according to the vibration interval duration of the mold includes: Obtaining the vibration interval duration of the mold when pouring the pipe raw material; If the vibration interval duration meets the vibration interval duration condition, it is determined that the flow continuity of the pipe material does not meet the requirement, and the cooling water flow rate of the corresponding length section of the mold that meets the vibration interval duration condition is increased. Among them, the cooling water flow rate is positively correlated with the vibration interval duration, the vibration interval duration condition is that the vibration interval duration is greater than the preset interval duration, and the position of the corresponding length segment of the mold is determined according to the flow rate of the pipe raw material and the vibration interval duration.

10. The method for preparing the graphene composite PE antibacterial pipe according to claim 1, characterized in that: The components of the graphene composite PE pipe include graphene and polyethylene.

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