Static mixer for a sheet production plant

Abstract

This utility model discloses a static mixer for sheet material production equipment, including a working tube, several first arc-shaped blocks, and several second arc-shaped blocks. A flow channel is provided within the working tube. The first and second arc-shaped blocks are alternately arranged within the flow channel along the flow direction of the melt. Adjacent first and second arc-shaped blocks form a melt mixing zone. The melt to be mixed enters the flow channel from a melt pump and flows sequentially between the alternately arranged first and second arc-shaped blocks under the pressure of the melt pump. The arc-shaped concave surfaces of the first and second arc-shaped blocks cause the melt to split and tumble. When flowing through the melt mixing zone, the multiple sub-streams that split interweave and overlap. Compared to existing technologies, this invention utilizes the fluidity of the melt, through the outer contour and curved portion of the arc-shaped blocks, to achieve tumbling, folding, and wrapping of the melt flowing through the flow channel during its forward flow, thus achieving a mixing effect.

Description

Technical Field

[0001] This utility model relates to the technical field of sheet production equipment, and in particular to a static mixer for sheet production equipment. Background Technology

[0002] Polypropylene (PP) and polyethylene (PE) are two general-purpose thermoplastic resins. Blending them creates a composite material that combines the good rigidity and heat resistance of PP with the excellent flexibility, environmental stress cracking resistance, and low-temperature impact resistance of PE. PP / PE blend sheets, produced by melt blending followed by casting or calendering, have broad application prospects in packaging, automotive interiors, building waterproofing, and electronic device protection. Industrially, the production of these blend sheets typically involves melting PP and PE separately, then feeding them through an extruder into a melt pump for online melt blending in a static mixer, and finally extruding them through a die. The uniformity of the mixture directly determines the mechanical properties, appearance quality, and long-term stability of the sheet.

[0003] Currently, the commonly used static mixers are mainly Kenics type (helical blade type) and its derivatives (refer to Chinese patent publication numbers "CN224071688U" and "CN224127015U"), which are composed of a series of alternating left-handed and right-handed helical elements. The mixing principle of the above mixers is based on "segmentation-recombination". Specifically, the melt is segmented every time it passes through a helical element. The number of fluid layers theoretically increases exponentially with the increase of the number of elements. By continuously segmenting, the stripe spacing is reduced, and the apparent mixing between components is achieved.

[0004] However, when existing static mixers are used for melts with special blending behaviors, such as PP and PE, this multi-stage mixing method leads to the following prominent technical problems and defects: 1. In a conventional static mixer, the melt undergoes intense shearing and stretching as it passes through the various spiral elements. The more times the mixture is divided, the longer the cumulative shearing process. Both PP and PE are polyester polymers that are highly sensitive to shear and thermodynamics. Excessive shear can easily lead to molecular chain breakage, causing a decrease in the intrinsic viscosity of the melt. This not only weakens the mechanical strength of the sheet but also produces yellow or even charred material due to degradation, severely affecting the appearance and transparency of the sheet.

[0005] 2. The segmenting effect of the spiral element forces the high-viscosity polymer melt to flow in a relatively narrow, tortuous channel, resulting in significant pressure loss and increasing extruder energy consumption and equipment load. Simultaneously, conventional static mixers easily form flow dead zones and stagnation zones at the connection between the spiral element and the tube wall, as well as in the transition zone between elements. Small amounts of PP or PE melt remain in these areas for extended periods, undergoing thermal degradation and carbonization, leading to black spots and crystal points on the molded sheets, constituting molding quality defects.

[0006] 3. Although PP and PE can form a compatible amorphous state under certain conditions, they are prone to phase separation during cooling processing and molding. Furthermore, the viscosity and viscoelasticity of the two melts often differ. While simple repeated segmentation can refine the layered striations, it fails to produce sufficient macroscopic inversion, folding, and convection fusion. Due to the lack of structures enabling radial migration and overall volume exchange of materials, the mixture exhibits a strong "layering and thinning" characteristic, failing to truly break the macroscopic interface between the dispersed and continuous phases. This leads to serious problems such as fluctuating striations within the sheet, uneven local component separation, and microscopic layering caused by phase separation, making it difficult to obtain a uniform microstructure.

[0007] 4. When there is a significant difference in the melt viscosity of PP and PE, existing mixers tend to allow the low-viscosity component to pass through the flow channel with less resistance first, while the melt of the high-viscosity component is easily blocked in the segmentation zone, resulting in uneven distribution of the mixing ratio in the flow channel cross-section and sheet width direction, which further aggravates component separation.

[0008] It is evident that existing static mixers used for blending PP and PE into sheets suffer from defects such as insufficient mixing uniformity, high melt degradation pressure, and fluctuating sheet quality due to their reliance on multiple divisions and lack of low-shear tumbling and fusion of materials. Utility Model Content

[0009] The technical problem to be solved by this utility model is to provide a static mixer for sheet production equipment.

[0010] To achieve the above objectives, this utility model discloses a static mixer for sheet production equipment, comprising a working tube, a plurality of first arc-shaped blocks and a plurality of second arc-shaped blocks. Both ends of the working tube are provided with flanges, which are respectively connected to a melt pump and an extrusion die. A flow channel is provided inside the working tube, and the flow channel is connected to both ends of the working tube.

[0011] A plurality of first arc-shaped blocks and a plurality of second arc-shaped blocks are alternately arranged in the flow channel along the flow direction of the melt. A melt mixing zone is formed between adjacent first arc-shaped blocks and second arc-shaped blocks. The concave arc surfaces of the first arc-shaped blocks and second arc-shaped blocks face the input end of the working tube. The blended melt is output from the melt pump and enters the flow channel through the input end of the working tube. Under the pressure drive of the melt pump, it flows sequentially between the alternately arranged first arc-shaped blocks and second arc-shaped blocks. The concave arc surfaces of the first arc-shaped blocks and second arc-shaped blocks cause the melt to split and flip. When flowing through the melt mixing zone, the multiple sub-streams that are split off intertwine and overlap, and finally form a highly uniform mixing state at the end of the flow channel and are output from the output end of the working tube.

[0012] Furthermore, both the first arc-shaped block and the second arc-shaped block have curved portions extending from their ends, with the curved portions bent toward the input end of the working tube.

[0013] Furthermore, the end of the curved portion is provided with a semi-circular chamfer.

[0014] Furthermore, the arc directions of the adjacent first arc blocks and the second arc blocks are opposite.

[0015] Furthermore, it also includes a cover, the top of the working tube is provided with a downward mounting recess, the flow channel is connected to the mounting recess, and the cover is movably placed in the mounting recess.

[0016] Furthermore, the first and second arc-shaped blocks are fixedly connected to the two sides along the length of the flow channel, respectively, and the top and bottom of the first and second arc-shaped blocks abut against the bottom of the cover and the bottom of the flow channel, respectively.

[0017] Compared with the prior art, the beneficial effects of this utility model are as follows: 1. By utilizing the fluidity of the melt, the outer contour and curved part of the arc block enable the melt flowing through the flow channel to achieve diversion, flipping, folding and wrapping during the forward flow process.

[0018] 2. By reducing excessive segmentation elements, the melt is prevented from repeatedly subjected to high-intensity shearing, effectively inhibiting the breakage and thermal degradation of PP and PE molecular chains, maintaining the intrinsic viscosity of the melt, thereby improving the mechanical strength and color of the sheet, and reducing defects such as yellowing, scorching, and black spots.

[0019] 3. The alternating arrangement of the first and second arc blocks reduces flow dead zones and stagnation areas formed at the connection of the spiral elements, prevents long-term carbonization of materials, and improves the cleanliness of the sheet appearance and production stability.

[0020] 4. The arrangement of the first and second arc-shaped blocks also allows PP and PE to fully convect and merge in the radial and flow directions, effectively suppressing micro-layering and stripe-like uneven composition caused by phase separation, and obtaining a sheet with a uniform structure. Attached Figure Description

[0021] Fig. 1 This is a schematic diagram of the working tube after the cover has been removed in this embodiment; Fig. 2 This is a schematic diagram of the cover installed on the working tube in this embodiment. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this utility model clearer, the following will be combined with... Figs. 1-2 The accompanying drawings provide a further detailed description of this utility model.

[0023] Reference Figs. 1-2 As shown, a static mixer for sheet material production equipment includes a working tube 1, a cover 2, several first arc-shaped blocks 3, and several second arc-shaped blocks 4. In this embodiment, the outer contour of the working tube 1 is square. Flanges 11 are provided at both ends of the working tube 1, and the flanges 11 are integrally formed with the working tube 1. In use, the two ends of the working tube 1 are respectively connected to the output end of a screw melt pump (not shown in the figure) and the input end of an extrusion die (not shown in the figure) via the flanges 11.

[0024] The working tube 1 has a flow channel 12 inside, which is connected to both ends of the working tube 1. A mounting recess 13 is located at the top of the working tube 1, and the flow channel 12 is connected to the mounting recess 13. A cover 2 is detachably bolted and placed in the mounting recess 13. When cleaning the inside of the working tube 1, loosen the bolts screwed onto the cover 2 and remove the cover 2 upwards to open the flow channel 12 for easy cleaning.

[0025] Several first arc-shaped blocks 3 and several second arc-shaped blocks 4 are respectively arranged at intervals on both sides of the horizontal direction within the flow channel 12 along the flow direction of the melt.

[0026] Furthermore, adjacent first arc-shaped blocks 3 and second arc-shaped blocks 4 are staggered and form a melt mixing zone 5. In this embodiment, the concave arc surfaces of the first arc-shaped block 3 and the second arc-shaped block 4 both face the input end 14 of the working tube 1.

[0027] The arc direction of the second arc block 4 is opposite to that of the first arc block 3.

[0028] Specifically, the first end of the first arc-shaped block 3 is connected to one side of the flow channel 12 along its length, and its end is set towards the center of the flow channel 12. The bottom of the first arc-shaped block 3 is connected to the bottom of the flow channel 12, and the top of the first arc-shaped block 3 is flush with the bottom of the mounting recess 13. When the cover 2 is placed on the working tube 1, the top of the first arc-shaped block 3 abuts against the bottom of the cover 2.

[0029] The second arc-shaped block 4 in this embodiment is set in the same way as the first arc-shaped block 3, and will not be described again here.

[0030] In this embodiment, the arc length of the second arc block 4 is the same as that of the first arc block 3.

[0031] Furthermore, both the first arc-shaped block 3 and the second arc-shaped block 4 have curved portions 6 extending from their ends, which are bent towards the input end 14 of the working tube body 1. In this embodiment, the curved portion 6 is integrally formed with the first arc-shaped block 3 and the second arc-shaped block 4. The end of the curved portion 6 is provided with a semi-circular chamfer 61, which facilitates the flow of the melt while avoiding cutting the melt. In this embodiment, the overall shape of the second arc-shaped block 4 is consistent with that of the first arc-shaped block 3, and will not be described further here. At the same time, the curved portions 6 of the first arc-shaped block 3 and the curved portions 6 of the second arc-shaped block 4 are vertically aligned.

[0032] The working principle of this equipment is as follows: The PP and PE blend melt is output by the melt pump and enters the flow channel 12 from the input end 14 of the working tube 1. Under the pressure drive of the melt pump, it flows sequentially between several alternating first arc blocks 3 and several second arc blocks 4. During the forward flow of the melt, it first contacts the first arc block 3. The arc concave surface of the first arc block 3 divides the melt into at least two sub-streams. Each sub-stream undergoes its first rotation and reversal along the arc concave surface of the first arc block 3. Subsequently, the melt continues to flow forward and comes into contact with the second arc block 4. Since the arc direction of the second arc block 4 is opposite to that of the first arc block 3, the melt that has been initially mixed by the first arc block 3 undergoes a second twist and split. At this time, the adjacent sub-streams intersect and overlap in the melt mixing zone 5. Through the alternating arrangement of the first arc block 3 and the second arc block 4, the melt continuously undergoes a cycle of splitting-twisting-merging-re-splitting during the flow process, and finally forms a highly uniform mixing state at the end of the flow channel 12 and is output from the output end of the working tube 1. Compared to the direct cutting of melt in the prior art, this embodiment utilizes the fluidity of the melt to achieve flipping, folding and wrapping of the melt flowing through the flow channel by using the outer contour and curved part of the arc block; Furthermore, by reducing excessive segmentation elements, this equipment structure avoids the melt from repeatedly enduring high-intensity shearing, effectively inhibiting the breakage and thermal degradation of PP and PE molecular chains, maintaining the intrinsic viscosity of the melt, thereby improving the mechanical strength and color of the sheet, and reducing defects such as yellowing, scorching, and black spots. The alternating arrangement of the first and second arc blocks reduces flow dead zones and stagnation areas formed at the connection of the spiral elements, prevents long-term carbonization of materials, and improves the cleanliness of the sheet appearance and production stability. Unlike pure segmentation and mixing, the arrangement of the first and second arc-shaped blocks allows PP and PE to fully convect and fuse in the radial and flow directions, effectively suppressing microscopic stratification and stripe-like uneven composition caused by phase separation, and obtaining a sheet with a uniform structure.

[0033] Of course, the above embodiments are only for illustrating the technical concept and features of this utility model. Their purpose is to enable those skilled in the art to understand the content of this utility model and implement it accordingly. They cannot be used to limit the protection scope of this utility model. All modifications made in accordance with the spirit of the main technical solution of this utility model should be covered within the protection scope of this utility model.

Claims

1. A static mixer for sheet production equipment, characterized in that, It includes a working tube (1), several first arc blocks (3) and several second arc blocks (4). Both ends of the working tube (1) are provided with flanges (11). The flanges (11) at both ends of the working tube (1) are respectively connected to the melt pump and the extrusion die. A flow channel (12) is provided in the working tube, and the flow channel (12) is connected to both ends of the working tube (1). Several first arc-shaped blocks (3) and several second arc-shaped blocks (4) are alternately arranged in the flow channel (12) along the flow direction of the melt. A melt mixing zone (5) is formed between adjacent first arc-shaped blocks (3) and second arc-shaped blocks (4). The concave arc surfaces of the first arc-shaped blocks (3) and the second arc-shaped blocks (4) are all facing the input end (14) of the working tube (1). The blended melt is output from the melt pump and enters the flow channel (12) through the input end of the working tube (1). Under the pressure drive of the melt pump, it flows sequentially between several alternately arranged first arc-shaped blocks (3) and several second arc-shaped blocks (4). The melt is split and overturned by the concave arc surfaces of the first arc-shaped blocks and the second arc-shaped blocks (4). When flowing through the melt mixing zone (5), the multiple sub-streams that are split off intertwine and overlap, and finally form a highly uniform mixing state at the end of the flow channel (12) and are output from the output end of the working tube (1).

2. The static mixer for sheet production equipment according to claim 1, characterized in that, Both the first arc block (3) and the second arc block (4) have a curved portion (6) extending from their ends, and the curved portion (6) is bent toward the input end (14) of the working tube (1).

3. The static mixer for sheet production equipment according to claim 2, characterized in that, The end of the curved portion (6) is provided with a semi-circular chamfer (61).

4. The static mixer for sheet production equipment according to claim 1, characterized in that, The adjacent first arc block (3) has an arc direction opposite to that of the second arc block (4).

5. The static mixer for sheet production equipment according to claim 1, characterized in that, It also includes a cover (2), and the top of the working tube (1) is provided with an installation recess (13) facing downward. The flow channel (12) is connected to the installation recess (13), and the cover (2) is movably covered in the installation recess (13).

6. The static mixer for sheet production equipment according to claim 5, characterized in that, The first arc-shaped block (3) and the second arc-shaped block (4) are fixedly connected to the two sides of the flow channel (12) along the length direction, respectively. The top and bottom of the first arc-shaped block (3) and the second arc-shaped block (4) abut against the bottom of the cover (2) and the bottom of the flow channel (12), respectively.

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