Treatment systems and methods for thermoplastic polyurethane melts

Abstract

A processing system for thermoplastic polyurethane melt includes a first screw extruder and a collecting funnel. The first screw extruder includes a cylindrical outer shell and a first screw disposed within the shell. The outer shell has a first discharge hole, a second discharge hole, and a third discharge hole arranged along the extension direction of the first screw. The first, second, and third discharge holes are located at the rear of the first screw extruder along the extension direction of the first screw and are spaced apart from each other. The collecting funnel is located below the first screw extruder and includes a funnel body and a funnel cover plate disposed on top of the funnel body. The funnel cover plate has three feed holes, the positions of which correspond to the first, second, and third discharge holes, respectively.

Description

Technical Field

[0001] This application relates to a processing system for thermoplastic polyurethane melt and a processing method for thermoplastic polyurethane melt. Background Technology

[0002] TPU (thermoplastic polyurethane elastomer) is a partially crystalline material belonging to the thermoplastic elastomer category. Polyurethane elastomers are characterized by a segmented structure of macromolecules. Due to the different cohesive energy densities of these segments, ideally, the phase separates into crystalline "hard" and amorphous "soft" regions. The resulting two-phase structure determines the performance range of TPU. Thermoplastic polyurethane is a widely used plastic. Therefore, TPU is used in applications such as the automotive industry (e.g., dashboard housings, films, cable sheaths), the entertainment industry (as a deposition area), in athletic shoes (as functional and design elements), and in rigid-flexible combinations and many other applications as a flexible component.

[0003] Screw extruders are used to produce thermoplastic polyurethane. Their principle involves feeding liquid raw materials into the extruder inlet at a stoichiometric ratio using a high-precision liquid feeder. In the screw extruder, the screw is mounted on a splined shaft inside a closed cylinder, where the polyurethane reacts through continuous mixing and kneading. The material is mixed with additives such as resins and pigment concentrates, and then, after heating, extrusion, and shearing, becomes a smooth melt. Excess heat from the reaction is dissipated through the barrel wall. Based on the number of screws, screw extruders are classified as single-screw extruders and twin-screw extruders.

[0004] Screw extruders typically employ a cylindrical structure, meaning the melt temperature gradually decreases from the inlet to the outlet. This can affect the internal structure and properties of the polyurethane melt, leading to inconsistent product quality. Summary of the Invention

[0005] To address the aforementioned technical issues, it is desirable to develop a processing system for thermoplastic polyurethane melts that can remix and fully process polyurethane melts formed at different temperatures to form polyurethane particles with a uniform internal structure.

[0006] This application discloses a processing system for thermoplastic polyurethane melt, characterized in that the processing system includes a first screw extruder and a collecting funnel; wherein the first screw extruder includes a cylindrical outer shell and a first screw disposed within the outer shell, and the outer shell is provided with a first discharge hole, a second discharge hole, and a third discharge hole arranged along the extension direction of the first screw; wherein the first discharge hole, the second discharge hole, and the third discharge hole are disposed at the rear of the first screw extruder along the extension direction of the first screw and are spaced apart from each other by a certain distance; wherein the collecting funnel is disposed below the first screw extruder and includes a funnel body and a funnel cover plate disposed on the top of the funnel body, the funnel cover plate being provided with three feed holes, the positions of the three feed holes corresponding to the first discharge hole, the second discharge hole, and the third discharge hole, respectively.

[0007] According to an optional embodiment, the processing system further includes a screw feeder; wherein the screw feeder is disposed at the bottom of the collection funnel and includes two angled conical screws to agitate the material from the collection funnel and feed it into the next processing device.

[0008] According to an optional embodiment, the processing system further includes a second screw extruder; wherein the second screw extruder is connected to the screw feeder and includes a second screw to receive material from the screw feeder, agitate it, and feed it into the next processing unit.

[0009] According to an optional embodiment, the processing system further includes a water ring granulator; wherein the water ring granulator is connected to the end of the second screw extruder and includes a granulator housing, a water circulation chamber, a cutting blade, and a flushing channel; wherein the water circulation chamber is disposed in the granulator housing to receive material from the second screw extruder, wherein the cutting blade is rotatably disposed in the water circulation chamber to cut the material from the second screw extruder into granules; wherein the flushing channel is disposed around the cutting blade to flush away the material adhering to the inner wall of the water circulation chamber and the cutting blade, and the cut granules, preventing them from accumulating on the inner wall of the water circulation chamber and the cutting blade.

[0010] According to an optional embodiment, the processing system further includes a cooling unit; wherein the cooling unit is connected to the water ring granulator and includes a water cooling channel to cool the granules from the water ring granulator by means of cooling water.

[0011] According to an optional embodiment, the processing system further includes a centrifuge; wherein the centrifuge is connected to the cooling unit and includes a rotatable spin-drying drum and a centrifuge discharge port to dehydrate the granules from the cooling unit and discharge them via the centrifuge discharge port.

[0012] According to an optional embodiment, the processing system further includes a vibrating screen; wherein the vibrating screen is connected to a centrifuge and includes a vibrating screen, a first collector, and a second collector; wherein the vibrating screen receives granules from the centrifuge by means of a screen mesh, and by means of vibration of the screen mesh, granules with an outer diameter smaller than the screen mesh aperture fall below the screen mesh, while granules with an outer diameter larger than the screen mesh aperture remain on the screen mesh; wherein the screen mesh is arranged at an angle to allow granules remaining on the screen mesh to slowly move to the edge of the screen mesh during vibration, and then fall from the edge of the screen mesh; wherein the first collector is arranged near the edge of the screen mesh to collect granules larger than or equal to the screen mesh aperture; wherein the second collector is arranged below the screen mesh to collect granules smaller than the screen mesh aperture.

[0013] According to an optional embodiment, the processing system further includes a conveying device; wherein the conveying device is connected to the vibrating screen and the first screw extruder to selectively convey the granules collected in the first collector and / or the second collector to the first screw extruder for remelting and extrusion.

[0014] According to an optional embodiment, the first screw extruder is configured such that the extension direction of its first screw is perpendicular to the extension direction of the second screw of the second screw extruder.

[0015] According to an optional embodiment, the first screw extruder is configured such that the extension direction of its first screw is parallel to the extension direction of the second screw of the second screw extruder.

[0016] According to an optional embodiment, the first screw extruder is a segmented screw extruder and includes multiple processing sections arranged end to end; wherein each processing section includes a screw and an independent temperature control system to adjust the temperature of each processing section according to the reaction characteristics of different stages.

[0017] According to an optional embodiment, the first screw extruder includes a conical or cylindrical housing and a conical first screw disposed within the housing, such that the material at both ends of the first screw has different pressures and temperatures.

[0018] This application also proposes a method for processing thermoplastic polyurethane melt, characterized in that the method includes the following steps:

[0019] S101: Collect TPU melt at three different locations in the extension direction of the first screw of the first screw extruder;

[0020] S102: The collected TPU melt is mixed and fed into the second screw extruder for stirring;

[0021] S103: Cutting TPU melt into granules in a water ring granulator;

[0022] S104: The cut granules are initially screened and dehydrated using a cooling unit and a centrifuge;

[0023] S105: Using a vibrating screener to screen the primary and dewatered granules, so as to separate granules with a size greater than or equal to the screen aperture of the vibrating screener from granules with a size smaller than the screen aperture of the vibrating screener.

[0024] S106: Collect granules with a size greater than or equal to the screen aperture of the vibrating screen and granules with a size smaller than the screen aperture of the vibrating screen, and selectively convey the granules with a size greater than or equal to the screen aperture of the vibrating screen and / or the granules with a size smaller than the screen aperture of the vibrating screen to the first screw extruder for remelting and extrusion by means of a conveying device.

[0025] The processing system for thermoplastic polyurethane melt according to this application can remix and fully process polyurethane melts formed at different temperatures to form polyurethane particles with uniform internal structure. Attached Figure Description

[0026] A more complete understanding of the foregoing and other aspects of this application will be gained from the detailed description that follows, in conjunction with the accompanying drawings. It should be noted that the scale of the drawings may vary for clarity, but this will not affect the understanding of this application.

[0027] Figure 1 This is a side view of a processing system for thermoplastic polyurethane melt according to this application.

[0028] Figure 2 This is a partial top view of a processing system for thermoplastic polyurethane melt according to this application.

[0029] Figure 3 This is a flowchart of a method for processing thermoplastic polyurethane melt according to this application. Detailed Implementation

[0030] Exemplary embodiments of this application will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of this application are shown in the drawings, it should be understood that this application may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of this application and to fully convey the scope of this application to those skilled in the art.

[0031] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0032] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0033] It should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be interpreted as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "a plurality of" or "several" means two or more, unless otherwise explicitly specified.

[0034] It should be noted that the terms "installation", "connection", and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components.

[0035] Figure 1 This is a side view of a processing system for thermoplastic polyurethane melt according to this application. The processing system includes a first screw extruder 10, a collecting funnel 11, a screw feeder 12, a second screw extruder 13, a water ring granulator 14, a cooling unit 15, a centrifuge 16, a vibrating screen 17, and a conveying device 18.

[0036] The first screw extruder 10 includes a cylindrical outer casing 100 and a first screw 101 disposed within the casing. Three discharge holes are arranged on the outer casing 100 along the extending direction of the first screw 101. The first discharge hole 102 is located in the middle of the first screw extruder 10, the second discharge hole 103 is located at the end of the first screw extruder 10, and the third discharge hole 104 is located between the first discharge hole 102 and the second discharge hole 103. In the first screw extruder 10, the temperature along the extending direction of the first screw 101 does not decrease linearly, but rather is lower at both ends and higher in the middle. In other words, the temperature near the first discharge hole 102 is higher than the temperature near the third discharge hole 104, and the temperature near the third discharge hole 104 is higher than the temperature near the second discharge hole 103.

[0037] A collecting funnel 11 is disposed below the first screw extruder 10 and includes a funnel body 110 and a funnel cover plate 111 disposed on top of the funnel body 110. The funnel cover plate 111 is provided with three feed holes 112 (see...). Figure 2 The positions of the three feed holes 112 correspond to the first discharge hole 102, the second discharge hole 103, and the third discharge hole 104, respectively, so that the TPU melt discharged from the first discharge hole 102, the second discharge hole 103, and the third discharge hole 104 can pass through the corresponding feed holes 112 and fall into the funnel body 110.

[0038] A screw feeder 12 is disposed at the bottom of the collecting hopper 11 and includes two angled, co-rotating conical screws 120. The two conical screws 120 are positioned near the end of the second screw 130 of the second screw extruder 13. The two conical screws 120 rotate in the same direction or in opposite directions to agitate the mixture of TPU melt from the collecting hopper 11 and feed it into the second screw extruder 13, and then into the next processing unit.

[0039] The second screw extruder 13 is connected to the screw feeder 12 and includes a second screw 130 to receive a mixture of TPU melt from the screw feeder 12, and to agitate and feed the mixture of TPU melt from the screw feeder 12 into a next processing unit.

[0040] The water ring granulator 14 is connected to the end of the second screw extruder 13 and includes a granulator housing, a water circulation chamber, a cutting blade, and a flushing channel. The water circulation chamber is disposed within the granulator housing to receive TPU melt from the second screw extruder 13. The cutting blade is rotatably disposed within the water circulation chamber to cut the partially solidified TPU melt into granules. The flushing channel is disposed around the cutting blade to wash away solidified TPU melt and cut granules adhering to the inner wall of the water circulation chamber and the cutting blade, preventing their accumulation on the inner wall of the water circulation chamber and the cutting blade.

[0041] Cooling unit 15 is connected to water ring granulator 14 and includes water cooling channel 150 to cool the uncut TPU melt and cut granules from water ring granulator 14 by means of cooling water, forming larger TPU blocks and smaller granules.

[0042] Centrifuge 16 is connected to cooling unit 15 and includes a rotatable spin-drying drum 160 and centrifuge discharge port 161 to dehydrate TPU blocks and granules from cooling unit 15 and discharge them via centrifuge discharge port 161.

[0043] A vibrating screen 17 is connected to a centrifuge 16, specifically to the centrifuge discharge port 161, and includes a vibrating screen 170, a first collector 171, and a second collector 172. The vibrating screen 170 receives TPU blocks and granules from the centrifuge 16 via a screen mesh. Vibration of the screen mesh causes granules with an outer diameter smaller than the mesh aperture to fall below the screen, while TPU blocks and granules with an outer diameter larger than the mesh aperture remain on the screen. The screen mesh is inclined to allow the TPU blocks and granules remaining on the screen to slowly move to the edge of the screen during vibration and then fall off. The first collector 171 is located near the edge of the screen to collect granules larger than or equal to the mesh aperture. The second collector 172 is located below the screen to collect granules smaller than the mesh aperture. Depending on the final application or size requirements of the pellets, the pellets collected by the first collector 171 and / or the second collector 172 may be selectively conveyed to the first screw extruder 10 by means of a conveying device 18 (e.g., a pipe or conveyor belt) for remelting and extrusion.

[0044] Figure 2 This is a top view of a processing system for thermoplastic polyurethane melt according to this application. For clarity, in Figure 2 Only the first screw extruder 10, the collecting funnel 11, the screw feeder 12, and the second screw extruder 13 are depicted, and the first screw extruder 10 and the second screw extruder 13 are indicated by dashed lines. For example... Figure 2 As shown, the line connecting the three feed holes 112 on the funnel cover plate 111 of the collecting funnel 11 is parallel to the extension direction BB of the second screw 130 of the second screw extruder 13. Since the positions of the three feed holes 112 correspond to the first discharge hole 102, the second discharge hole 103, and the third discharge hole 104 of the first screw extruder 10, respectively, in... Figure 2 The extension direction of the first screw 101 of the first screw extruder 10 (omitted in the original text) is parallel to the extension direction of the second screw 130 of the second screw extruder 13. However, it is understood that the first screw extruder 10 can also be configured at other angles, for example, such that the extension direction of the first screw 101 of the first screw extruder 10 is perpendicular to the extension direction of the second screw 130 of the second screw extruder 13.

[0045] This application also includes the following implementation methods.

[0046] In one embodiment, the first screw extruder 10 is a segmented screw extruder and includes multiple processing sections arranged end-to-end. Each processing section includes a screw and an independent temperature control system, allowing the temperature of each processing section to be adjusted according to the reaction characteristics of different stages.

[0047] In one embodiment, the first screw extruder 10 includes a conical or cylindrical housing and a conical first screw 101 disposed within the housing, such that the TPU melt has different pressures and temperatures at the two ends of the first screw 101.

[0048] Figure 3 This is a flowchart of a method for processing thermoplastic polyurethane melt according to this application. The processing method includes the following steps:

[0049] S101: TPU melt is collected at three different locations in the extension direction of the first screw 101 of the first screw extruder 10;

[0050] S102: The collected TPU melt is mixed and fed into the second screw extruder 13 for stirring;

[0051] S103: TPU melt is cut into granules in water ring granulator 14;

[0052] S104: The cut granules are initially screened and dehydrated by means of cooling unit 15 and centrifuge 16;

[0053] S105: The primary and dewatered granules are screened by means of the vibrating screen 17 to separate granules with a size greater than or equal to the screen aperture of the vibrating screen (17) and granules with a size smaller than the screen aperture of the vibrating screen (17).

[0054] S106: Collect granules with a size greater than or equal to the screen aperture of the vibrating screener (17) and granules with a size smaller than the screen aperture of the vibrating screener (17), and selectively convey the granules with a size greater than or equal to the screen aperture of the vibrating screener (17) and / or the granules with a size smaller than the screen aperture of the vibrating screener (17) to the first screw extruder 10 by means of the conveying device 18 for remelting and extrusion.

[0055] The foregoing description of the embodiments has been provided for illustrative and descriptive purposes. It is not intended to be exhaustive or to limit the embodiments to the described variations. Many modifications and variations will be apparent to those skilled in the art. These embodiments were chosen and described to best illustrate the principles and practical applications, enabling those skilled in the art to understand them from their various implementations and modifications suited to their intended use. Within the framework of these embodiments, the aforementioned components and features may be combined among different implementations.

Claims

1. A processing system for thermoplastic polyurethane melt, characterized in that, The processing system includes a first screw extruder (10) and a collection funnel (11); The first screw extruder (10) includes a cylindrical outer shell (100) and a first screw (101) disposed in the outer shell, and the outer shell (100) is provided with a first discharge hole (102), a second discharge hole (103) and a third discharge hole (104) arranged along the extension direction of the first screw (101); The first discharge hole (102) is located in the middle of the first screw extruder (10), the second discharge hole (103) is located at the end of the first screw extruder (10), and the third discharge hole (104) is located between the first discharge hole (102) and the second discharge hole (103) so that the TPU melt discharged from different positions has different temperatures. The collecting funnel (11) is located below the first screw extruder (10) and includes a funnel body (110) and a funnel cover plate (111) located on the top of the funnel body (110). The funnel cover plate (111) is provided with three feed holes (112). The positions of the three feed holes (112) correspond to the first discharge hole (102), the second discharge hole (103) and the third discharge hole (104) respectively, so as to collect and mix TPU melts with different temperatures. The processing system also includes a vibrating screen (17); The vibrating screen (17) is connected to the centrifuge (16) and includes a vibrating screen (170), a first collector (171) and a second collector (172); The vibrating screen (170) receives the granules from the centrifuge (16) by means of the screen mesh, and by means of the vibration of the screen mesh, the granules with an outer diameter smaller than the screen mesh aperture fall below the screen mesh, while the granules with an outer diameter larger than the screen mesh aperture remain on the screen mesh. The screen is set at an angle so that the particles remaining on the screen can slowly move to the edge of the screen during vibration and then fall off the edge of the screen. The first collector (171) is located near the edge of the screen to collect granules larger than or equal to the screen aperture. The second collector (172) is located below the screen to collect particles smaller than the screen aperture.

2. The processing system for thermoplastic polyurethane melt according to claim 1, characterized in that, The processing system also includes a screw feeder (12); The screw feeder (12) is located at the bottom of the collection funnel (11) and includes two angled conical screws (120) to mix the material from the collection funnel (11) and feed it into the next processing device.

3. The processing system for thermoplastic polyurethane melt according to claim 2, characterized in that, The processing system also includes a second screw extruder (13); The second screw extruder (13) is connected to the screw feeder (12) and includes a second screw (130) to receive material from the screw feeder (12), agitate it, and feed it into the next processing unit.

4. The processing system for thermoplastic polyurethane melt according to claim 3, characterized in that, The processing system also includes a water ring granulator (14); The water ring granulator (14) is connected to the end of the second screw extruder (13) and includes a granulator housing, a water circulation chamber, a cutting blade, and a flushing channel. The water circulation chamber is located inside the granulator casing to receive material from the second screw extruder (13). The cutting blade is rotatably disposed in the water circulation chamber to cut the material from the second screw extruder (13) into pellets; The flushing channel is located around the cutting edge to wash away the material and cut particles adhering to the inner wall of the water circulation chamber and the cutting edge, preventing them from accumulating on the inner wall of the water circulation chamber and the cutting edge.

5. The processing system for thermoplastic polyurethane melt according to claim 4, characterized in that, The processing system also includes a cooling unit (15); The cooling unit (15) is connected to the water ring granulator (14) and includes a water cooling channel (150) to cool the pellets from the water ring granulator (14) by means of cooling water.

6. The processing system for thermoplastic polyurethane melt according to claim 5, characterized in that, The processing system also includes a centrifuge (16); The centrifuge (16) is connected to the cooling unit (15) and includes a rotatable spin-drying drum (160) and a centrifuge discharge port (161) to dehydrate the granules from the cooling unit (15) and discharge them through the centrifuge discharge port (161).

7. The processing system for thermoplastic polyurethane melt according to claim 1, characterized in that, The processing system also includes a conveying device (18); The conveying device (18) is connected to the vibrating screen (17) and the first screw extruder (10) to selectively convey the granules collected in the first collector (171) and / or the second collector (172) to the first screw extruder (10) for remelting and extrusion.

8. The processing system for thermoplastic polyurethane melt according to any one of claims 1-7, characterized in that, The first screw extruder (10) is configured such that the extension direction of its first screw (101) is perpendicular to the extension direction of the second screw (130) of the second screw extruder (13).

9. The processing system for thermoplastic polyurethane melt according to any one of claims 1-7, characterized in that, The first screw extruder (10) is configured such that the extension direction of its first screw (101) is parallel to the extension direction of the second screw (130) of the second screw extruder (13).

10. The processing system for thermoplastic polyurethane melt according to any one of claims 1-7, characterized in that, The first screw extruder (10) is a segmented screw extruder and includes multiple processing sections arranged end to end; Each processing section includes a screw and an independent temperature control system to adjust the temperature of each processing section according to the reaction characteristics of different stages.

11. The processing system for thermoplastic polyurethane melt according to any one of claims 1-7, characterized in that, The first screw extruder (10) includes a conical or cylindrical housing and a conical first screw (101) disposed in the housing, such that the material at both ends of the first screw (101) has different pressures and temperatures.

12. A method for processing thermoplastic polyurethane melt, characterized in that, The method includes the following steps: S101: TPU melt is collected in the extension direction of the first screw (101) of the first screw extruder (10) through the first discharge hole (102), the second discharge hole (103) and the third discharge hole (104) arranged along the extension direction of the first screw (101), wherein the first discharge hole (102) is located in the middle of the first screw extruder (10), the second discharge hole (103) is located at the end of the first screw extruder (10), and the third discharge hole (104) is located between the first discharge hole (102) and the second discharge hole (103); S102: The collected TPU melt is mixed and fed into the second screw extruder (13) for stirring; S103: Cut TPU melt into granules in a water ring granulator (14); S104: The cut granules are initially screened and dehydrated by means of a cooling unit (15) and a centrifuge (16); S105: The primary and dewatered granules are screened by means of a vibrating screener (17) to separate granules with a size greater than or equal to the screen aperture of the vibrating screener (17) from granules with a size smaller than the screen aperture of the vibrating screener (17). S106: Collect granules with a size greater than or equal to the screen aperture of the vibrating screener (17) and granules with a size smaller than the screen aperture of the vibrating screener (17) respectively, and selectively convey the granules with a size greater than or equal to the screen aperture of the vibrating screener (17) and / or the granules with a size smaller than the screen aperture of the vibrating screener (17) to the first screw extruder (10) for remelting and extrusion by means of a conveying device (18).

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