Polymerizing kettle flexible resin production device and method

Abstract

The invention belongs to the technical field of polyvinyl chloride resin production, and discloses a polymerization kettle flexible resin production device and method, the device comprises a polymerization kettle and a cooling assembly, the cooling assembly comprises a hollow stirring rod, and a cold source is arranged in the stirring rod; the connecting rod is fixedly connected with one end of the stirring rod; the air cylinder is horizontally arranged, a piston rod of the air cylinder is fixedly connected with one end of the connecting rod, and the air cylinder is connected with a driving source used for driving the air cylinder to rotate circumferentially; according to the scheme, the piston rod of the air cylinder is controlled to extend or retract step by step, so that the stirring rod realizes radial horizontal displacement while performing circumferential rotation by taking the rotating central axis of the polymerization kettle as a circle center, and the stirring rod can move towards the kettle wall from the central area of the polymerization kettle along a spiral track; the cold source in the stirring rod continuously contacts with materials at different radial positions in the kettle for heat exchange along with the spiral movement of the stirring rod; the problem of local temperature difference of polyvinyl chloride in the later period of the polymerization kettle is solved.

Description

Technical Field

[0001] This solution belongs to the field of polyvinyl chloride resin production technology, specifically involving a production apparatus and method for flexible resin in a polymerization reactor. Background Technology

[0002] Flexible polyvinyl chloride (PVC) resin specifically refers to SG-5 type PVC products with characteristics such as moderate apparent density, thin granular film, high plasticizer absorption, excellent whiteness and transparency, few fisheye defects, and good processing performance. It is a flexible processing resin material that meets market demands.

[0003] The production of polyvinyl chloride (PVC) resin requires raw material storage and pretreatment equipment, polymerization reactor, feeding device and post-processing equipment. Among them, the polymerization reactor is the core reaction equipment of the entire production process, providing a stable environment for the polymerization reaction with controlled temperature and pressure. After the reaction reaches the set conversion rate, the polymerization is terminated by adding a terminator through the terminator feeding device, directly producing primary SG-5 type flexible PVC resin. Subsequently, after centrifuge dehydration, dryer removal of moisture, and screening of particle size by sieving machine, the finished product that meets market requirements is formed.

[0004] A method for improving the conversion rate of a large-scale domestically produced PVC polymerization reactor is disclosed in the existing publication (announcement) number CN117285667A. In the third step, when the polymerization reaction time in the polymerization reactor reaches 200 min, the pressure drop reaches 15 kPa to 22 kPa. At this time, the circulating water in the jacket of the polymerization reactor is turned off. When the temperature of the polymerization reactor rises by 10°C, the circulating water in the jacket of the polymerization reactor is turned on again to cool the polymerization reactor. When the pressure drop in the polymerization reactor reaches 150 kPa, the required amount of terminator is added. After the polymerization reaction is terminated, polyvinyl chloride is discharged.

[0005] For example, in the aforementioned polymerization reactor, a jacketed ring is installed and water is supplied through the jacketed ring to cool the resin inside the reactor. (See attached instruction manual.) Figure 1As shown, the existing polymerization reactor cavity is divided into a central region A (stirring center region) and an edge region B (region near the reactor wall). When cooling is performed on the reactor body through jacketed circulating water, the cooling medium first passes through region B and then to region A. Under the action of the stirring rod, the temperature of the resin in the reactor decreases. However, this is based on the premise that the resin in region B can be quickly mixed into region A under the rapid rotation of the stirring rod, thus causing the temperature of all resins to decrease synchronously. However, in the later stage of the PVC reaction in the polymerization reactor (polymerization growth stage), the PVC particles have basically solidified, but there are still unreacted viscous components remaining on the surface, forming a viscous non-Newtonian fluid. If rapid stirring is used, the shear force cannot achieve uniform dispersion as in the low viscosity stage. Instead, it will forcibly pull and squeeze the particles, causing the particles with strong surface viscosity to stick together and agglomerate. Moreover, the rapid stirring will generate a shear heat effect, causing the temperature in local areas to rise. Therefore, in the later stage of the PVC reaction in the polymerization reactor, even if the jacketed circulating water continues to cool, the temperature of the material in the reactor still shows a local temperature difference. Summary of the Invention

[0006] The purpose of this solution is to provide a production device for flexible resin in a polymerization reactor to mitigate the problem of localized temperature differences in polyvinyl chloride during the later stages of polymerization.

[0007] To achieve the above objectives, this solution provides a production apparatus for flexible resin in a polymerization reactor, comprising a polymerization reactor and a cooling assembly, wherein the cooling assembly includes: A stirring rod, wherein the stirring rod is hollow and a cold source is provided inside the stirring rod; A connecting rod, which is fixedly connected to one end of the stirring rod; The cylinder is horizontally arranged, and one end of the piston rod of the cylinder is fixedly connected to the connecting rod. The cylinder is connected to a drive source for driving its circumferential rotation.

[0008] The principle and effect of this scheme are as follows: (1) In the later stage of polymerization reaction, while the driving source drives the cylinder to rotate slowly in a circumferential direction, the piston rod of the cylinder is controlled to extend or retract gradually, so that the stirring rod rotates in a circumferential direction with the rotation axis of the polymerization vessel as the center, and achieves radial horizontal displacement. Its movement trajectory forms an Archimedean spiral, so that the stirring rod can move from the center area of ​​the polymerization vessel along the spiral trajectory towards the vessel wall, and can also return from the vessel wall area along the spiral trajectory to the rotation center. The cold source in the stirring rod continuously contacts and exchanges heat with the material at different radial positions in the vessel with its spiral movement. (2) On the one hand, the spiral movement allows the stirring rod with the cold source to move from the stirring center to the edge area, so that the heat exchange range between the cold source and the material is maximized; on the other hand, the stirring method of the spiral trajectory can make the material at the edge mix with the material in the center faster. Combined with the direct heat exchange of the cold source at different radial positions, it can alleviate the local temperature difference caused by viscosity in the later stage of polymerization, avoid hollow particles caused by overheating in the center area, and will not destroy the morphology of resin particles due to rapid stirring.

[0009] Furthermore, the stirring rod is provided with a jacket, which extends spirally along the length of the stirring rod and fits against the inner wall of the stirring rod. The jacket and the inner wall of the stirring rod enclose a closed cold source circulation cavity. Both ends of the jacket are connected to a circulation pump through pipes.

[0010] The principle and effect of this solution are as follows: the spiral jacket and the inner wall of the stirring rod form a cold source flow cavity. The circulating pump drives the cold source to flow along the spiral path, so that the cold source transfers the cold energy to the material in the reactor through the wall of the stirring rod. With the spiral movement of the stirring rod, the cold energy covers the area from the center to the edge, reducing the local temperature difference in the later stage of polymerization.

[0011] Furthermore, the jacket includes a first jacket and a second jacket, wherein the cold source flow chamber area of ​​the second jacket is smaller than that of the first jacket; there are two sets of the first jacket, and one end of each set of the first jacket is connected to the circulation pump through a pipe, and the other end is connected to both ends of the second jacket respectively; the two sets of the first jacket are located on the upper and lower sides of the second jacket respectively, and the two sets of the first jacket are located on the upper and lower sides of the stirring area of ​​the polymerization reactor respectively, and the second jacket is located in the middle area of ​​the stirring area of ​​the polymerization reactor.

[0012] The principle and effect of this scheme are as follows: When the cold source initially enters the stirring rod, it first contacts the material on the upper / lower sides of the stirring zone to absorb heat. By the time the cold source reaches the middle area of ​​the stirring zone, its own temperature has increased, and a temperature difference still exists in the middle area. This scheme connects the large-flow-area first jacket on the upper and lower sides with the small-flow-area second jacket in the middle area. The circulating pump drives the cold source to first absorb heat from the upper / lower side material through the large-flow first jacket, and then as it flows into the small-flow-area second jacket, the reduced flow cross-sectional area increases the cold source flow rate and enhances the heat exchange intensity, thereby compensating for the decrease in cold energy in the middle area. Simultaneously, within one cycle, by periodically switching the inlet and outlet ends of the two sets of first jackets, the upper and lower first jackets alternately serve as the cold source inlet (initial low-temperature cold source) and outlet (heat-increasing cold source after heat absorption), resulting in a more uniform temperature of the material in the reactor along the axial direction.

[0013] Furthermore, the cylinder includes a cylinder body and a piston. The cylinder body has an air inlet that communicates with the inner cavity of the cylinder body. The piston is slidably disposed in the cylinder body and is fixedly connected to one end of the piston rod. The cylinder also includes a vacuum pump that is connected to the polymerization reactor via a pipeline.

[0014] The principle and effect of this solution are as follows: During the later stages of polymerization, a vacuum pump gradually creates a negative pressure environment inside the polymerization reactor, driving the piston to slide towards the air inlet. This causes the piston rod to extend, which in turn moves the stirring rod along the reactor wall. This solution uses the pressure inside the reactor to drive the stirring rod, eliminating the need for electronic control of the cylinder to move the piston, making it more suitable for the high-temperature and humid environment inside the reactor.

[0015] Furthermore, the stirring rod is equipped with stirring blades; the driving source is a motor, which is mounted on the lid of the polymerization reactor. The output shaft of the motor passes through the lid and is fixedly connected to the cylinder body, with the connection point located on the rotation axis of the polymerization reactor.

[0016] The principle and effect of this solution are as follows: the motor is used to drive the cylinder to rotate, which in turn drives the stirring rod to rotate. The connection point between the two is located on the central axis of rotation, so that the stirring rod rotates around the central axis. During the later stage of polymerization, the horizontal movement trajectory of the stirring rod is always radially extended or retracted with the central axis as the reference, and it will not rotate eccentrically.

[0017] Furthermore, the stirring blade includes a hollow mother segment blade body and multiple daughter segment blade bodies. The outer wall of the mother segment blade body is fixedly connected to the outer wall of the stirring rod. The daughter segment blade bodies are slidably disposed within the mother segment blade body. A compression spring is provided within the mother segment blade body. One end of the compression spring is fixedly connected to the inner wall of the mother segment blade body, and the other end is fixedly connected to the inner wall of the daughter segment blade body.

[0018] The principle and effect of this scheme are as follows: Since the stirring rod needs to move and rotate horizontally inside the polymerization reactor, in order to avoid collision between the stirring blade and the reactor wall, the stirring blade is set as a retractable stirring blade. Since the rotation speed of the stirring rod is relatively low in the later stage of polymerization, the stirring blade only contacts the reactor wall and will not generate a large impact. Therefore, when the sub-segment blade contacts the reactor wall, the compression spring is compressed, thereby causing the sub-segment blade to retract into the mother segment blade. After the sub-segment blade moves away from the reactor wall, the restoring force of the compression spring drives the sub-segment blade to extend out of the mother segment blade.

[0019] Furthermore, the stirring blade includes a stirring blade body and a sleeve. The inner wall of the sleeve is fixedly connected to the outer wall of the stirring rod. The sleeve has a sliding groove. The stirring blade body is slidably disposed in the sliding groove, and a spring is provided in the sliding groove. One end of the spring is fixedly connected to the sliding groove, and the free end is fixedly connected to the stirring blade body.

[0020] The principle and effect of this solution are as follows: Although retractable stirring blades can be used to avoid collisions with the vessel wall, when the stirring rod moves the stirring blades to contact one side of the vessel wall, a large space remains between the stirring blades and the other side of the vessel wall after the blades retract. This reduces the stirring effect on the material in that area and creates a temperature difference. In this solution, the stirring blade body can elastically extend and retract radially along the stirring rod. When the end of the stirring rod contacts one side of the vessel wall, the spring is compressed, causing the stirring rod to move towards the other side of the vessel wall. This does not reduce the stirring range of the stirring blades and avoids temperature differences.

[0021] Furthermore, it also includes a separation component, which includes a suction nozzle and a slider. The slider is slidably mounted on the stirring rod, and the suction nozzle is fixedly mounted on the slider. The air inlet of the suction nozzle faces vertically downward, and the air outlet is connected to a vacuum pump through a pipe.

[0022] The principle and effect of this scheme are as follows: (1) When preparing polyvinyl chloride resin in a polymerization reactor, in the later stage of polymerization, local temperature difference or uneven stirring often leads to incomplete reaction inside the particles. The residual monomer gas is wrapped inside the particles and forms hollow particles with a lower density than solid particles after cooling. This makes the PVC particles impure and requires separation of hollow particles. However, the existing technology mostly involves screening in other equipment in the later stage, which is quite troublesome. In this scheme, because the hollow particles contain gas and have a lower density than the slurry and solid particles, they will naturally float to the surface of the slurry under the action of buoyancy. The vacuum pump provides suction to the nozzle to draw negative pressure into the reactor, thereby further promoting the hollow particles to float and gather faster. At the same time, the slider drives the nozzle to rotate along the stirring rod. The air inlet end of the nozzle is vertically downward and aligned with the hollow particles on the liquid surface. The vacuum pump sucks up the hollow particles through the negative pressure and discharges them through the pipe, thus realizing the separation of hollow particles from solid particles. (2) Since the liquid surface in the polymerization reactor is relatively wide, this design can move the stirring rod horizontally, which can drive the suction nozzle to move synchronously, thereby suctioning the hollow particles on the entire liquid surface. At the same time, the suction nozzle is set on the stirring rod, and the rotation of the stirring rod generates a vortex, which can make the hollow particles gather as much as possible towards the center of rotation, making it easier for the suction nozzle to suck up the hollow particles.

[0023] Furthermore, the separation assembly also includes a collection box and a filter screen. The collection box has an inlet and an outlet. The inlet is connected to the air outlet of the suction nozzle through a pipe. The outlet is connected to a vacuum pump through a pipe. The filter screen is located inside the collection box and between the inlet and the outlet.

[0024] The principle and effect of this scheme are as follows: the collection box receives the mixture of hollow particles and gas sucked up by the suction nozzle through the inlet. The filter screen is set between the inlet and the outlet to intercept the hollow particles and keep them in the collection box. The gas passes through the filter screen and is discharged by the vacuum pump through the outlet. The hollow particles in the collection box are then further processed.

[0025] A method for producing flexible resin in a polymerization reactor, comprising using a production apparatus for flexible resin in a polymerization reactor as described above, including the following steps: Step S10: The inner wall of the polymerization reactor is coated by a combination of steam atomization pre-condensation and wall coating agent atomization spraying, and then 10-12 parts by weight of wall coating agent are atomized and sprayed onto the reactor wall. Step S20: Start the stirring rod and stir at low speed. Add 4-6 parts by weight of low buffer to the polymerization reactor, followed by 56,000-57,000 parts by weight of 73.5℃ demineralized water and 49,000-49,500 parts by weight of vinyl chloride monomer. During the feeding process, add 40-42 parts by weight of dispersant in sequence. The dispersant is dispersant I, dispersant II, dispersant III, and dispersant IV in a weight ratio of 19:5:4-4.5:1. Dispersant I is a polymer with a mass concentration of 80%. The polymerization reaction system is constructed using polyvinyl alcohol (PVA), dispersant II (hydroxypropyl methylcellulose ether), dispersant III (45% PVA by mass), and dispersant IV (72% PVA by mass). The dispersants are added in the following order: first, add 80% PVA and 45% PVA by mass, then add hydroxypropyl methylcellulose ether and 72% PVA, followed by 29.5-31.0 parts by weight of initiator. The pH in the reactor is adjusted to 7.5-8.5. Step S30: Close the reactor, maintain the internal temperature at 56.0℃±0.5℃ and the pressure at 0.70MPa-0.95MPa, and carry out the polymerization reaction. When the reaction reaches the late stage of polymerization growth, enter the temperature-controlled stirring and separation stage. Step S40: Start the motor and circulation pump. The stirring rod rotates slowly around the central axis of the polymerization reactor. The circulation pump pumps the cold source into the jacket. The cold source flows along the cold source flow chamber and exchanges heat with the material through the wall of the stirring rod. Every preset interval, switch the connection state between the two sets of first jackets and the circulation pump, so that the two sets of first jackets alternately serve as the cold source inlet and outlet. At the same time, the vacuum pump gradually draws negative pressure into the polymerization reactor, causing the stirring rod to move from the center of the reactor to the reactor wall. Step S50: The separation component is started synchronously. Hollow particles gather towards the center of the vessel and float to the surface of the slurry. The nozzle sucks the mixture of hollow particles and gas into the nozzle and transports it to the collection box through the pipeline to separate the hollow particles from the solid particles. Step S60: The polymerization reaction proceeds for 250-280 minutes. When the pressure drop inside the reactor reaches the preset value, 60-65 parts by weight of a novel antioxidant terminator are added to the reactor to terminate the reaction. Stirring, temperature control and separation operations are stopped. After the reaction product is discharged, it is dehydrated by a centrifuge and the moisture is removed by a dryer to obtain the flexible polyvinyl chloride resin product.

[0026] The effects of this scheme are as follows: (1) The combined coating method of steam atomization pre-condensation and coating agent atomization spraying, combined with uniform atomization of the coating agent, reduces the plasticizers generated by sticking to the reactor in the traditional process, reduces the number of fish eyes of SG-5 resin from the source, and reduces the product appearance defects caused by the poor coating effect. (2) The traditional ternary dispersion system is upgraded to a quaternary dispersion system of 19:5:4-4.5:1, and the materials are added in the order of "first add 80% polyvinyl alcohol + 45% polyvinyl alcohol, then add ether + 72% polyvinyl alcohol". Combined with the effect of 73.5℃ isothermal desalination water and low buffer (4-6 parts by weight), the resin particle film is thinner, the apparent density is moderate, and the plasticizer absorption is significantly improved. At the same time, 60-65 parts by weight of new antioxidant terminator is used to replace the traditional terminator, which not only improves the whiteness and transparency of the resin, but also extends the thermal stability time, solving the problems of low oil absorption rate and poor whiteness of the original resin. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the internal structure of the polymerization reactor of the present invention; Figure 2 This is a schematic diagram of the external structure of a production apparatus for flexible resin in a polymerization reactor according to the present invention. Figure 3 This is a schematic diagram of the internal structure of a polymer reactor for producing flexible resin according to the present invention. Figure 4 This is a schematic diagram of the internal structure of the stirring rod of the present invention. Figure 1 ; Figure 5 This is a schematic diagram of the structure of the stirring blade of the present invention. Figure 1 ; Figure 6 This is a schematic diagram of the internal structure of the stirring blade of the present invention. Figure 1 ; Figure 7 This is a schematic diagram of the structure of the stirring blade of the present invention. Figure 1 ; Figure 8 This is a schematic diagram of the structure of the stirring blade of the present invention. Figure 2 ; Figure 9 This is a schematic diagram of the internal structure of the stirring blade of the present invention. Figure 2 ; Figure 10 This is a schematic diagram of the cylinder structure of the present invention; Figure 11 This is a schematic diagram of the internal structure of the collection box of the present invention.

[0028] The reference numerals in the accompanying drawings include: polymerization reactor 1, motor 11, cooling jacket 12, cooling assembly 2, stirring rod 21, rotary joint 211, bellows 212, water inlet 213, connecting rod 22, cylinder 23, piston rod 231, cylinder body 232, air inlet 2321, first chamber 2322, second chamber 2323, piston 233, tension spring 234, jacket 24, cold source circulation chamber 241, first jacket 242, second jacket 243, circulation pump 25, vacuum pump 26, stirring blade 27, mother section blade 271, daughter section blade 272, compression spring 273, stirring blade body 274, sleeve 275, slide groove 2751, spring 276, separation assembly 3, suction nozzle 31, slider 32, collection box 33, feed inlet 331, discharge outlet 332, filter screen 34. Detailed Implementation

[0029] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention. Example 1: Please see Figures 1-3 This embodiment provides a production apparatus for flexible resin in a polymerization reactor, employing a 137m³ polymerization reactor 1, including a polymerization reactor 1, a cooling assembly 2, a vacuum pump 26, and a separation assembly 3. The specific structure and connections are as follows: A drive motor 11 is fixedly installed on the reactor lid of the polymerization reactor 1, and a pressure relief valve (not shown) is provided on the lid. A cooling jacket 12 is coiled around the outer wall of the polymerization reactor 1 in the stirring zone. The cooling jacket 12 is used to cool the edge region B (e.g., Figure 1 The cooling component 2 (as shown) is used for cooling, which is existing technology and will not be described in detail. The cooling component 2 includes a stirring rod 21, a connecting rod 22, a cylinder 23, and a jacket 24.

[0030] Please see Figure 1 , Figure 3 and Figure 4The stirring rod 21 has a hollow structure, and inside it is fitted a jacket 24 that extends spirally along its length. The jacket 24 is semi-circular, and one end is tightly fitted to the inner wall of the stirring rod 21. The two together form a closed spiral cold source flow cavity 241, in which the cold source can flow along a spiral path within the cold source flow cavity 241, exchanging heat with the material in the reactor through the wall of the stirring rod 21. The jacket 24 is specifically divided into two sets of first jackets 242 and one set of second jackets 243. The cross-sectional area of ​​the cold source flow cavity 241 of the second jacket 243 is smaller than that of the cold source flow cavity 241 of the first jacket 242. The two sets of first jackets 242 are located on the upper and lower sides of the second jacket 243, respectively, and respectively cover the upper and lower spaces of the stirring area of ​​the polymerization reactor 1. The second jacket 243 is located in the middle area of ​​the stirring area of ​​the polymerization reactor 1, that is, the first jackets 242 correspond to the upper and lower A1 areas, and the second jacket 243 corresponds to the middle A2 area (e.g., Figure 1 (As shown). One end of each of the two sets of first jackets 242 is connected to the circulating pump 25 through a pipe, and the other end is connected to the two ends of the second jacket 243 respectively. When the circulating pump 25 is working, it can continuously pump the cold source into the cold source flow chamber 241: the cold source first exchanges heat with the material in the corresponding area through the first jackets 242 on the upper and lower sides, and then flows into the second jacket 243 in the middle area; because the temperature of the cold source rises after passing through the first jacket 242, the smaller flow chamber area of ​​the second jacket 243 can increase the flow rate of the cold source and enhance the heat exchange intensity to compensate for the decrease in coldness in the middle area. At the same time, every preset period, such as 5 minutes, the connection state between the two sets of first jackets 242 and the circulating pump 25 is switched by the valve, so that the two sets of first jackets 242 alternately serve as the cold source inlet and outlet, ensuring the temperature uniformity of the material in the reactor in the axial direction. It should be noted that, since the cold source needs to be circulated, a cooler (not shown) is installed at the inlet of the circulation pump 25. When the cold source flows back to the circulation pump 25, it first passes through the cooler to lower the temperature before being transported to the jacket 24 by the circulation pump 25.

[0031] Please see Figure 3 , Figures 5-9 The stirring rod 21 is equipped with two types of stirring blades 27 adapted to different working conditions. There are three sets of stirring blades 27, spaced apart along the length of the stirring rod 21. Each set of stirring blades 27 includes two pairs of stirring blades 27 arranged in a cross shape. The first type of stirring blade 27 includes a hollow mother blade body 271 and multiple daughter blade bodies 272. The outer wall of the mother blade body 271 is fixedly connected to the outer wall of the stirring rod 21 via a connecting sleeve. The daughter blade bodies 272 are slidably embedded in the inner cavity of the mother blade body 271. A compression spring 273 is also provided inside the mother blade body 271. One end of the compression spring 273 is fixed to the inner wall of the mother blade body 271, and the other end is fixed to the inner wall of the daughter blade bodies 272. When the stirring rod 21 drives the stirring blades 27 to move towards the wall of the polymerization reactor 1, the daughter blade bodies 272, after contacting the reactor wall, compress the compression spring 273 and retract into the mother blade body 271 (e.g., ...). Figure 5 and Figure 6 As shown), when the stirring rod 21 moves away from the vessel wall, the restoring force of the compression spring 273 pushes the sub-section blade 272 to extend, ensuring that the stirring range covers the corresponding area. The second type of stirring blade 27 includes a stirring blade body 274 and a sleeve 275. The sleeve 275 has a through hole (not shown) for the stirring rod 21 to pass through. The inner wall of the through hole is fixedly connected to the outer wall of the stirring rod 21. The sleeve 275 has two horizontally extending grooves 2751, which are staggered vertically and arranged in a cross shape, corresponding to two pairs of stirring blade bodies 274. The stirring blade bodies 274 are slidably fitted into the grooves 2751. A spring 276 is installed in each groove 2751. One end of the spring 276 is fixed to the inner wall of the groove 2751, and the free end is fixedly connected to the middle position of the stirring blade body 274 (e.g., ...). Figures 7-9 As shown), the stirring blade body 274 is allowed to elastically extend and retract radially along the stirring rod 21. Even if the end of the stirring rod 21 contacts one side of the vessel wall, the compression of the spring 276 can cause the stirring blade body 274 to extend to the other side, avoiding the formation of stirring dead zones and further ensuring uniform temperature.

[0032] Please see Figure 3 and Figure 10The cylinder 23 includes a cylinder body 232 and a piston 233. The cylinder body 232 is horizontally arranged and has an air inlet 2321 that communicates with the inner cavity of the cylinder body 232. The air inlet 2321 communicates with the interior of the polymerization reactor 1. The piston 233 is slidably disposed on the cylinder body 232 and is interference-fitted with the inner wall of the cylinder body 232. The piston 233 divides the inner cavity of the cylinder body 232 into two chambers, namely a first chamber 2322 and a second chamber 2323 formed by the piston 233 and the cylinder body 232 at both ends. The second chamber 2323 is a normal pressure chamber. The air inlet 2321 communicates with the first chamber 2322. A piston rod 231 is provided, with one end of the piston rod 231 fixedly connected to the piston 233. A tension spring 234 is provided in the second chamber 2323, with one end of the tension spring 234 fixedly connected to the piston 233 and the free end fixedly connected to the inner wall of the cylinder 232. This spring is used to drive the piston 233 back to its initial position, thereby causing the piston rod 231 to retract into the cylinder 232. The tension spring 234 is already at its compression limit position in the initial state, so even if the polymerization reactor 1 is under positive pressure, the piston 233 will not move, reducing the space of the second chamber 2323. This ensures that the stirring rod 21 is always located at the central axis of the polymerization reactor 1 in its natural state. The output shaft of the motor 11 passes through the reactor lid and is fixedly connected to the cylinder 232. The connection point is strictly coincident with the rotational central axis of the polymerization reactor 1, ensuring that the cylinder 23 can drive the subsequent components to rotate stably around the central axis and avoid eccentric rotation. The connecting rod 22 is L-shaped, with one end fixedly connected to the piston rod 231 and the other end fixedly connected to the stirring rod 21. This converts the extension and retraction of the cylinder 23 into the radial movement of the stirring rod 21 along the polymerization reactor 1, and it rotates circumferentially under the drive of the motor 11. The free end of the stirring rod 21 is connected to a rotary joint 211, and the other end of the rotary joint 211 is connected to a bellows 212. The other end of the bellows 212 is connected to the bottom of the polymerization reactor 1. The stirring rod 21 has a water inlet 213. The pipeline connecting the jacket 24 and the circulating pump 25 enters the stirring rod 21 from the water inlet 213, passes through the bellows 212, and finally connects to the circulating pump 25, so that while the stirring rod 21 can rotate, a cold source is supplied to the jacket inside the stirring rod 21.

[0033] Please see Figure 3 , Figure 4 and Figure 11It also includes a vacuum pump 26, which is connected to the polymerization reactor 1 through a sealed pipe and a connector; the separation component 3 includes a suction nozzle 31, a slider 32, a collection box 33 and a filter screen 34. The slider 32 is slidably mounted on the stirring rod 21 and can move along the length of the stirring rod 21. The suction nozzle 31 is fixed on the slider 32. According to the preset liquid level in the reactor, the suction nozzle 31 is moved above the liquid level and the air inlet end of the suction nozzle 31 is vertically downward and aligned with the liquid level; the collection box 33 is fixedly installed on the inner wall of the stirring reactor 1. The collection box 33 has an inlet 331 and an outlet 332. The air outlet end of the suction nozzle 31 is connected to the inlet 331 through a pipe, and the outlet 332 is connected to the vacuum pump 26 through a pipe. The filter screen 34 is horizontally installed in the collection box 33 and located between the inlet 331 and the outlet 332, so that hollow particles are temporarily stored in the collection box 33. The vortex generated by the rotation of the stirring rod 21 causes the hollow particles to gather towards the center of the polymerization reactor 1. Under the negative pressure of the vacuum pump 26, the suction nozzle 31 gradually draws the polymerization reactor 1 to a slightly negative pressure state. The pressure difference formed inside the reactor drives the piston 233 of the cylinder 23 to slide towards the air inlet 2321, thereby driving the piston rod 231 to extend. This causes the stirring rod 21 to rotate circumferentially around the rotation axis of the polymerization reactor 1, achieving radial horizontal displacement. Its movement trajectory forms an Archimedean spiral, allowing the stirring rod 21 to move gradually from the center area of ​​the polymerization reactor 1 along the spiral trajectory (similar to the structure of a mosquito coil) towards the reactor wall, and also from the reactor wall area back to the rotation center along the spiral trajectory. The cold source inside the stirring rod 21 continuously contacts and exchanges heat with the material at different radial positions inside the reactor as it moves spirally. This driving method does not require additional electrical control devices and is more suitable for the high temperature and humidity environment inside the reactor. At the same time, the negative pressure environment can promote the floating of hollow particles in the material. At the same time, the suction nozzle 31 draws in the mixture of hollow particles and gas, which is then transported through the pipeline to the collection box 33. The filter screen 34 intercepts the hollow particles and retains them in the collection box 33, while the gas passes through the filter screen 34 and is discharged from the discharge port 332, thus achieving the separation of hollow particles from solid particles without the need for subsequent additional screening equipment.

[0034] Example 2: To better realize the above-mentioned production apparatus for flexible resin in a polymerization reactor, this application also provides a method for producing flexible resin in a polymerization reactor, the specific steps of which are as follows: Step S10: The inner wall of polymerization reactor 1 is treated by a combination of steam atomization pre-condensation removal and wall coating agent atomization spraying to remove condensate in the steam pipeline entering the reactor and reduce the adhesion of the reactor surface; then 10-12 parts by weight of wall coating agent are atomized and sprayed onto the reactor wall of polymerization reactor 1 to reduce the number of fish eyes in flexible polyvinyl chloride resin from the source and avoid plasticizer residue affecting product quality; Step S20: Start stirring rod 21 at low speed and add 4-6 parts by weight of low buffer to polymerization reactor 1; then simultaneously add 56,000-57,000 parts by weight of 73.5℃ demineralized water and 49,000-49,500 parts by weight of vinyl chloride monomer to polymerization reactor 1. During the feeding process, add 40-42 parts by weight of dispersant in a specific order. This dispersant is dispersant I, dispersant II, dispersant III, and dispersant IV in a weight ratio of 19:5:4-4.5:1, wherein... Dispersant I is 80% polyvinyl alcohol (PVA), dispersant II is hydroxypropyl methylcellulose ether (HMCME), dispersant III is 45% PVA, and dispersant IV is 72% PVA. The order of addition is to add dispersant I and dispersant III first, followed by dispersant II and dispersant IV. After the vinyl chloride monomer is added, 29.5-31.0 parts by weight of initiator are added to polymerization reactor 1 to adjust the pH to 7.5-8.5, forming a stable polymerization reaction system. The combination of a low-buffered agent and 73.5℃ isothermal deionized water in the quaternary dispersion system results in a thinner resin particle film, a moderate apparent density, and increased plasticizer absorption. Step S30: Close the polymerization reactor 1 and maintain the internal temperature at 56.0℃±0.5℃ and the pressure at 0.70MPa-0.95MPa to carry out the polymerization reaction. Avoid local overheating that could cause the formation of hollow particles and ensure that the reaction proceeds smoothly to the later stage of polymerization growth. Step S40: Start the motor 11 and the circulating pump 25. The motor 11 drives the cylinder 23 and the stirring rod 21 to rotate slowly around the central axis of the polymerization reactor 1. The circulating pump 25 continuously pumps the cold source into the jacket 24. The cold source flows along the cold source flow chamber 241 and exchanges heat with the material through the wall of the stirring rod 21. During this period, the connection status of the two sets of first jackets 242 and the circulating pump 25 is switched every 10 minutes, so that the two sets of first jackets 242 alternately serve as the cold source inlet and outlet, ensuring uniform axial temperature inside the reactor. At the same time, the vacuum pump 26 is started to gradually draw negative pressure into the polymerization reactor 1. The pressure difference inside the reactor drives the piston 233 to slide, which drives the piston rod 231 to extend, so that the stirring rod 21 moves slowly from the center of the polymerization reactor 1 to the reactor wall, expanding the heat exchange range of the cold source. Step S50: Start the separation component 3. The vortex generated by the rotation of the stirring rod 21 causes the hollow particles to gather towards the center of the polymerization kettle 1 and float to the surface of the slurry. The slider 32 moves along the stirring rod 21, causing the suction nozzle 31 to cover the surface of the slurry. Under the negative pressure of the vacuum pump 26, the suction nozzle 31 sucks in the mixture of hollow particles and gas, and transports it to the collection box 33 through the pipeline. After the mixture enters the collection box 33, the filter screen 34 intercepts the hollow particles and retains them in the collection box 33. The gas passes through the filter screen 34 and is discharged from the outlet 332, realizing the separation of hollow particles and solid particles and improving the purity of the product. Step S60: The polymerization reaction proceeds for 250-280 minutes. When the pressure drop inside the polymerization reactor 1 reaches the preset value, 60-65 parts by weight of a novel antioxidant terminator is added to the reactor to terminate the reaction. Compared with traditional terminators, this terminator can improve the whiteness and transparency of the resin and extend the thermal stability time. The stirring rod 21 is stopped from rotating, the circulating pump 25 is stopped from delivering cold source, and the separation component 3 is stopped from working. After the reaction product is discharged from the polymerization reactor 1, it is dehydrated by a centrifuge and the moisture is removed by a dryer in sequence. Finally, a flexible polyvinyl chloride resin product with moderate apparent density, thin particle film, high plasticizer absorption, excellent whiteness and transparency, few fisheye defects, and good processing performance is obtained.

[0035] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific structures and characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A production apparatus for flexible resin in a polymerization reactor, comprising a polymerization reactor (1) and a cooling assembly (2), characterized in that, The cooling component (2) includes: Stirring rod (21), the stirring rod (21) is a hollow stirring rod (21), and a cold source is provided inside the stirring rod (21); Connecting rod (22), which is fixedly connected to one end of stirring rod (21); The cylinder (23) is horizontally arranged, and the piston rod (231) of the cylinder (23) is fixedly connected to one end of the connecting rod (22). The cylinder (23) is connected to a drive source for driving its circumferential rotation.

2. The apparatus for producing flexible resin in a polymerization reactor according to claim 1, characterized in that: The stirring rod (21) is provided with a jacket (24), which extends spirally along the length of the stirring rod (21) and fits against the inner wall of the stirring rod (21). The jacket (24) and the inner wall of the stirring rod (21) enclose a closed cold source circulation cavity (241). Both ends of the jacket (24) are connected to a circulation pump (25) through pipes.

3. The apparatus for producing flexible resin in a polymerization reactor according to claim 2, characterized in that: The jacket (24) includes a first jacket (242) and a second jacket (243). The area of ​​the cold source flow chamber (241) of the second jacket (243) is smaller than the area of ​​the cold source flow chamber (241) of the first jacket (242). There are two sets of the first jacket (242), and one end of each set of the first jacket (242) is connected to the circulating pump (25) through a pipe, and the other end is connected to both ends of the second jacket (243). The two sets of the first jacket (242) are located on the upper and lower sides of the second jacket (243), and the two sets of the first jacket (242) are located on the upper and lower sides of the stirring area of ​​the polymerization reactor (1), and the second jacket (243) is located in the middle area of ​​the stirring area of ​​the polymerization reactor (1).

4. The apparatus for producing flexible resin in a polymerization reactor according to claim 1, characterized in that: The cylinder (23) includes a cylinder body (232) and a piston (233). The cylinder body (232) has an air inlet (2321) and the air inlet (2321) is connected to the inner cavity of the cylinder body (232). The piston (233) is slidably disposed on the cylinder body (232) and the piston (233) is fixedly connected to one end of the piston rod (231). The cylinder also includes a vacuum pump (26), which is connected to the polymerization reactor (1) through a pipeline.

5. The apparatus for producing flexible resin in a polymerization reactor according to claim 4, characterized in that: The stirring rod (21) is provided with stirring blades (27); the driving source is a motor (11), the motor (11) is located on the lid of the polymerization reactor (1), the output shaft of the motor (11) passes through the lid and is fixedly connected to the cylinder (232), and the connection point is located on the rotation axis of the polymerization reactor (1).

6. The apparatus for producing flexible resin in a polymerization reactor according to claim 5, characterized in that: The stirring blade (27) includes a hollow mother blade (271) and multiple daughter blades (272). The outer wall of the mother blade (271) is fixedly connected to the outer wall of the stirring rod (21). The daughter blades (272) are slidably disposed inside the mother blade (271). A compression spring (273) is provided inside the mother blade (271). One end of the compression spring (273) is fixedly connected to the inner wall of the mother blade (271), and the other end is fixedly connected to the inner wall of the daughter blade (272).

7. The apparatus for producing flexible resin in a polymerization reactor according to claim 5, characterized in that: The stirring blade (27) includes a stirring blade body (274) and a sleeve (275). The inner wall of the sleeve (275) is fixedly connected to the outer wall of the stirring rod (21). The sleeve (275) has a sliding groove (2751). The stirring blade body (274) is slidably disposed in the sliding groove (2751). A spring (276) is provided in the sliding groove (2751). One end of the spring (276) is fixedly connected to the sliding groove (2751), and the free end is fixedly connected to the stirring blade body (274).

8. The apparatus for producing flexible resin in a polymerization reactor according to claim 4, characterized in that: It also includes a separation component (3), which includes a suction nozzle (31) and a slider (32). The slider (32) is slidably mounted on the stirring rod (21), and the suction nozzle (31) is fixedly mounted on the slider (32). The air inlet of the suction nozzle (31) is vertically downward, and the air outlet is connected to the vacuum pump (26) through a pipe.

9. The apparatus for producing flexible resin in a polymerization reactor according to claim 8, characterized in that: The separation component (3) also includes a collection box (33) and a filter screen (34). The collection box (33) is located inside the stirring vessel (1). The collection box (33) has an inlet (331) and an outlet (332). The inlet (331) is connected to the air outlet of the suction nozzle (31) through a pipe. The outlet (332) is connected to the vacuum pump (26) through a pipe. The filter screen (34) is located inside the collection box (33) and between the inlet (331) and the outlet (332).

10. A method for producing flexible resin in a polymerization reactor, comprising using a production apparatus for flexible resin in a polymerization reactor as described in any one of claims 1-9, characterized in that, Includes the following steps: Step S10: The inner wall of the polymerization reactor (1) is coated by a combination of steam atomization pre-condensation and wall coating agent atomization spraying, and then 10-12 parts by weight of wall coating agent are atomized and sprayed onto the reactor wall; Step S20: Start the stirring rod (21) and stir at low speed. Add 4-6 parts by weight of low buffer to the polymerization reactor (1), followed by 56,000-57,000 parts by weight of 73.5℃ deionized water and 49,000-49,500 parts by weight of vinyl chloride monomer. During the feeding process, add 40-42 parts by weight of dispersant in sequence. The dispersant is dispersant I, dispersant II, dispersant III and dispersant IV with a weight ratio of 19:5:4-4.5:

1. Dispersant I has a mass concentration of 80%. The polymerization reaction system is constructed by adding 80% polyvinyl alcohol and 45% polyvinyl alcohol by dispersant II, 45% polyvinyl alcohol by dispersant III, and 72% polyvinyl alcohol by dispersant IV. The dispersants are added in the following order: first, 80% polyvinyl alcohol and 45% polyvinyl alcohol by dispersant II, then hydroxypropyl methylcellulose ether and 72% polyvinyl alcohol by dispersant III, followed by 29.5-31.0 parts by weight of initiator. The pH of the reactor is adjusted to 7.5-8.

5. Step S30: Close the reactor, maintain the internal temperature at 56.0℃±0.5℃ and the pressure at 0.70MPa-0.95MPa, and carry out the polymerization reaction. When the reaction reaches the late stage of polymerization growth, enter the temperature-controlled stirring and separation stage. Step S40: Start the motor (11) and the circulation pump (25). The stirring rod (21) rotates slowly around the central axis of the polymerization reactor (1). The circulation pump (25) pumps the cold source into the jacket (24). The cold source flows along the cold source flow chamber (241) and exchanges heat with the material through the wall of the stirring rod (21). Every preset interval, switch the connection state between the two sets of first jackets (242) and the circulation pump (25) so that the two sets of first jackets (242) alternately serve as the cold source inlet and outlet. At the same time, the vacuum pump (26) gradually draws negative pressure into the polymerization reactor (1) so that the stirring rod (21) moves from the center of the reactor to the reactor wall. Step S50: The separation component (3) is started synchronously. Hollow particles gather towards the center of the vessel and float to the surface of the slurry. The suction nozzle (31) sucks the mixture of hollow particles and gas into the suction nozzle (31) and transports it to the collection box (33) through the pipeline to separate the hollow particles from the solid particles. Step S60: The polymerization reaction proceeds for 250-280 minutes. When the pressure drop inside the reactor reaches the preset value, 60-65 parts by weight of a novel antioxidant terminator are added to the reactor to terminate the reaction. Stirring, temperature control and separation operations are stopped. After the reaction product is discharged, it is dehydrated by a centrifuge and the moisture is removed by a dryer to obtain the flexible polyvinyl chloride resin product.

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