CN-122006628-A - Multistage circulating rubber devolatilization device and method based on microwave-infrared coupling heating

CN122006628ACN 122006628 ACN122006628 ACN 122006628ACN-122006628-A

Abstract

The invention discloses a multistage circulating rubber devolatilization device and method based on microwave-infrared coupling heating, and belongs to the technical field of polymer material processing. The device comprises a quartz glass tank body, a metal microwave shielding cavity, a microwave generator, an infrared lamp tube, a multistage falling strip distributor and a bottom direct-connection screw pump. The invention directly heats the rubber melt by utilizing the volume heating of microwaves and is assisted with infrared radiation to compensate the surface temperature drop, thereby avoiding the thermal crosslinking and coking of the rubber caused by the traditional wall surface heating. The device adopts an intermittent circulation process, and by on-line switching of the coarse pore, the middle pore and the micropore distributors and the gradient regulation and control of the vacuum degree and the temperature, the rubber solution forms falling strips matched with the rheological properties of the rubber solution in different devolatilization stages. The bottom wide-mouth screw pump realizes zero-holding liquid direct discharge and eliminates flowing dead angles. The invention effectively realizes the efficient and mild devolatilization of the high-viscosity heat-sensitive synthetic rubber, the final volatile content can be stably controlled below 500ppm, and the product does not generate obvious thermal crosslinking.

Inventors

XI ZHENHAO
ZHAO LING
WANG YIAN
QIU XIAOYI
HUANG HUAN
WANG XUESONG
CUI ZHAOQI
LU GUOLONG

Assignees

华东理工大学

Dates

Publication Date: 20260512
Application Date: 20260415

Claims (8)

1. The utility model provides a multistage circulation rubber devolatilization device based on microwave-infrared coupling heating which characterized in that includes: a quartz glass tank (16) for containing rubber material and performing devolatilization treatment; A metal microwave shielding cavity (15), wherein the quartz glass tank body (16) is arranged inside the metal microwave shielding cavity (15); the microwave generator (10) is arranged on the side wall of the metal microwave shielding cavity (15) and is used for heating the rubber material in the quartz glass tank body (16) in volume; the infrared lamp tube (11) is arranged between the quartz glass tank body (16) and the metal microwave shielding cavity (15) and is used for radiation compensation of the surface temperature drop of the rubber material; The multistage falling strip distributor comprises a falling strip distributor A (12), a falling strip distributor B (13) and a falling strip distributor C (14) which are arranged at the top of a quartz glass tank body (16) in parallel and are sequentially reduced in aperture, and the falling strip distributor A, the falling strip distributor B (5) and the falling strip distributor C (14) are respectively controlled to be on-off through a material inlet valve A (4), a material inlet valve B (6); The inlet of the screw pump (23) is directly connected to the bottom of the quartz glass tank body (16) through a wide-mouth transition section, the outlet end of the screw pump is provided with a material outlet pressure detection system (21), and the screw pump is divided into two paths, one path is connected to a discharge port through a material outlet valve (19), and the other path is connected to the inlet of the multistage falling strip distributor at the top of the quartz glass tank body (16) through a material circulating valve (20); A material inlet (22) arranged at the upstream of the screw pump (23) and used for injecting a rubber solution to be devolatilized into the system; A vacuum pump (18) connected to the quartz glass tank (16) through a vacuum valve (8); a nitrogen bottle (17) connected to the quartz glass tank (16) through a nitrogen valve (9); The tank pressure detection system (2) is arranged on the quartz glass tank (16); a tank body temperature detection system (3) arranged on the quartz glass tank body (16); the material inlet pressure detection system (1) is arranged on an inlet pipeline of the multi-stage falling bar distributor; and the atmosphere valve (7) is arranged at the top of the quartz glass tank body (16).
2. The multistage circulating rubber devolatilization device based on microwave-infrared coupling heating according to claim 1, wherein the pore diameters of the falling strip distributor A (12), the falling strip distributor B (13) and the falling strip distributor C (14) are configured to be 6-10 mm for a coarse pore distributor, 4-6 mm for a medium pore distributor and 2-4 mm for a micropore distributor, so as to adapt to rheological characteristics of gradually rising viscosity in the rubber devolatilization process.
3. The multistage circulating rubber devolatilization device based on microwave-infrared coupling heating according to claim 1, wherein the screw pump (23) is a wide-mouth direct-connection screw pump, and the inlet of the screw pump and the bottom of the quartz glass tank body (16) adopt a zero-liquid-holding direct-connection mode without a liquid collecting area structure, so that flow dead angles are eliminated.
4. A multistage circulating rubber devolatilization method based on microwave-infrared coupling heating by adopting the device of any one of claims 1-3, which is characterized by comprising the following steps: S1, system replacement and oxygen discharge, namely closing all valves, opening a vacuum valve (8), pumping out gas in a quartz glass tank body (16) through a vacuum pump (18), then closing the vacuum valve (8), opening a nitrogen valve (9) and a nitrogen cylinder (17), introducing nitrogen into the quartz glass tank body (16), repeating the operations of pumping and charging nitrogen for at least three times, monitoring the pressure through a tank body pressure detection system (2), and completing replacement and discharge of oxygen in the system; S2, feeding and establishing circulation, namely opening a screw pump (23), opening a material inlet (22), a material circulation valve (20) and a material inlet valve A (4), injecting a rubber solution to be devolatilized through the material inlet (22), filling a circulation pipeline under the driving of the screw pump (23), forming falling strips through a falling strip distributor A (12), falling the falling strips back to the bottom of a quartz glass tank body (16), monitoring pressure stability through a material inlet pressure detection system (1) and a material outlet pressure detection system (21), and closing the material inlet (22) after a liquid seal is established at the bottom of the tank, so that the device enters an independent closed loop circulation devolatilization mode; s3, primary devolatilization, namely starting a microwave generator (10) and an infrared lamp tube (11), setting heating temperature, opening a vacuum valve (8), adjusting a vacuum pump (18) to enable the quartz glass tank body (16) to be in a low vacuum state, enabling rubber solution to circularly flow through coarse falling strips formed by a falling strip distributor A (12), heating by utilizing the volume of microwaves and compensating surface temperature drop of infrared radiation to remove a large amount of volatile matters, and sampling and monitoring the volatile matters through a material outlet valve (19) to a first set value; S4, secondary devolatilization, namely when the volatile content is reduced to a first set value, closing a material inlet valve A (4), opening a material inlet valve B (5), adjusting a vacuum valve (8) to improve the vacuum degree in a quartz glass tank body (16) to a medium level, adjusting the heating power of a microwave generator (10) and an infrared lamp tube (11), enabling rubber solution to form medium-diameter falling strip circulation flow through a falling strip distributor B (13), enhancing gas-liquid mass transfer, and sampling and monitoring the volatile content to a second set value through a material outlet valve (19); S5, three-stage devolatilization, namely when the volatile content is reduced to a second set value, closing a material inlet valve B (5), opening a material inlet valve C (6), adjusting a vacuum valve (8) to enable the quartz glass tank body (16) to reach a limit high vacuum state, adjusting heating power of a microwave generator (10) and an infrared lamp tube (11), enabling rubber melt to circularly flow through micro falling strips formed by a falling strip distributor C (14), deeply removing residual volatile, and sampling and monitoring the volatile content to a third set value through a material outlet valve (19); s6, discharging, namely when the volatile content is reduced to a third set value, closing the vacuum valve (8) and the vacuum pump (18), opening the nitrogen valve (9) and the nitrogen cylinder (17) to break vacuum to positive pressure, closing the material circulation valve (20), opening the material outlet valve (19), and discharging a finished product through the screw pump (23).
5. The multistage circulating rubber devolatilization method based on microwave-infrared coupling heating according to claim 4, wherein the low vacuum state in step S3 is 30-80 kPa in absolute pressure, the medium vacuum state in step S4 is 5-30 kPa in absolute pressure, and the extreme high vacuum state in step S5 is 0.1-5 kPa in absolute pressure.
6. The multistage circulating rubber devolatilization method based on microwave-infrared coupling heating according to claim 4, wherein the heating temperature of the microwave generator (10) and the infrared lamp tube (11) in the steps S3 to S5 is increased step by step, wherein the primary devolatilization temperature is 120-150 ℃, the secondary devolatilization temperature is 150-170 ℃, and the tertiary devolatilization temperature is 170-200 ℃.
7. The method for devolatilizing a multistage circulating rubber based on microwave-infrared coupled heating as claimed in claim 4, wherein the first set value in steps S3 to S5 is 30000 to 50000ppm, the second set value is 3000 to 6000ppm, and the third set value is not more than 500ppm.
8. The method for devolatilizing the multistage circulating rubber based on microwave-infrared coupling heating as claimed in claim 4, wherein the rubber solution to be devolatilized is selected from ethylene propylene rubber, solution polymerized styrene-butadiene rubber or butyl rubber solution polymerized glue solution, and the solvent is selected from one or more of cyclohexane, n-hexane or Isopar E.

Description

Multistage circulating rubber devolatilization device and method based on microwave-infrared coupling heating Technical Field The invention relates to the technical field of high polymer material processing and chemical equipment, in particular to a multistage circulating rubber devolatilization device and method based on microwave-infrared coupling heating. Background Synthetic rubber (such as ethylene propylene rubber, solution polymerized styrene-butadiene rubber, butyl rubber and the like) is a base material in the modern industry and has wide application in the fields of automobiles, buildings, electronics and the like. In the traditional solution polymerization process, the activity of the early Ziegler-Natta catalyst system is low, high-concentration metal ions generally remain in the polymerization glue solution, washing and deashing must be carried out by a large amount of acidic water or hot water, and a wet condensation process with huge energy consumption, namely, high-temperature steam stripping is used for removing the solvent, is limited. However, with the progress of the synthetic rubber industry technology, particularly the wide application of high-activity catalyst systems such as metallocene and post-metallocene, the catalyst residue in the polymerization product is greatly reduced, so that the traditional water-washing ash removing process is not an essential link. The innovation of this chemical process provides a prerequisite for dry devolatilization. Compared with the wet process, the dry devolatilization directly heats and flashes the polymer solution or melt, utilizes the characteristic that the vaporization latent heat of the organic solvent is far lower than that of water, has the remarkable advantages of short flow, low energy consumption, no wastewater discharge and the like, and has become the necessary trend of industry development. However, the synthetic rubber melt generally has extremely high viscosity (thousands to tens of thousands of Pa.s) and extremely poor thermal conductivity (generally in the range of 0.15 to 0.25W/(m.K)), and most of the synthetic rubber molecular chains contain unsaturated double bonds, which are typical heat-sensitive materials. In the dry devolatilization process, how to solve the contradiction of low heat transfer efficiency, easy occurrence of thermal crosslinking denaturation, easy coking of the wall surface, uncontrollable residence time distribution and the like of the high-viscosity rubber solution or melt becomes a key bottleneck for restricting the industrial application of the technology. The prior art CN110639461a discloses a falling film devolatilizer and a falling film element thereof, and the device enables the material to flow along the element surface in a film forming way under the action of gravity through a specific falling film element structure so as to increase the evaporation area. While this design improves surface renewal to some extent, its heat input is still essentially dependent on the surface heat conduction of the walls or internals. Because the elastomeric melt is a poor conductor of heat, the heated walls must be maintained at a high degree of superheat (typically 30-50 ℃ higher than the bulk temperature) in order to ensure the activation energy required for devolatilization within the fluid. The heating mode of external heat and internal cooling causes the adherent fluid layer to be in a high temperature state for a long time, so that the free radical crosslinking reaction of the polymer chain is extremely easy to induce, a colloid coating and a coking layer which are difficult to remove are formed on the inner wall of the equipment, the heat transfer efficiency is deteriorated, and the peeled scorched particles pollute the product quality. The prior art CN115572337a discloses a polymer solution devolatilization method and apparatus which adopts a multi-stage flash evaporation technology, and a liquid collecting zone is arranged at the bottom of the devolatilizer in order to maintain the continuity of production and pumping pressure. While this design ensures suction head of the pump, the pool structure at the bottom can lead to severe material retention and flow dead angles for high viscosity non-newtonian fluids. In industrial production, this means that the residence time distribution of the material is extremely wide, a part of the material with a long residence time is susceptible to thermal crosslinking at high temperature, gel particles are formed, the consistency between product batches is deteriorated, and strict process control is difficult to achieve. The prior art CN117507293B discloses a process method for drying and devolatilizing halogenated butyl rubber based on microwave drying and treating tail gas, and introduces a microwave heating technology. However, this prior art is mainly directed to broken porous rubber particles, the object of treatment being in solid state accumulation mode, focusing on