Method and device for removing volatile components of polymer particles and application of method and device

Abstract

The invention provides a method and a device for removing volatile components in polymer particles and application of the method. The method comprises the following steps: removing the volatile components in the polymer particles by adopting a microwave fluidized bed; the method specifically comprises the following steps: heating polymer particles entering the devolatilization chamber by using a microwave generator, and introducing fluidizing gas into the devolatilization chamber at the same time. The device comprises a devolatilization chamber and a microwave generator, wherein the microwave generator can emit microwaves into the devolatilization chamber; the devolatilization chamber is provided with a feed port, a discharge port, an air inlet and an air outlet. The polymer obtained by the method disclosed by the invention has the advantages of low volatile component content, weak odor, environment friendliness, good safety and the like; the device disclosed by the invention is simple in structure, good in devolatilization effect and high in efficiency when being used for devolatilizing polymer particles.

Description

Technical Field

[0001] The invention relates to the technical field of polymer processing, and in particular to a method and device for removing volatile matter from polymer particles and application thereof. Background Art

[0002] During the polymer processing, the raw materials often contain too much water, gas or various volatile substances such as monomers, oligomers, solvents, etc., which makes the volatile component content of the obtained product too high, resulting in defects such as dull surface, dents, and bubbles inside the product, which seriously affects the quality of the product. The high content of volatile components in polymer products has an important impact not only on product quality, but also on post-system safety and environmental protection. Therefore, it is necessary to remove the volatile components in polymer products, that is, "devolatilization". With the deepening of people's understanding of green, healthy, safe, and environmental protection, as well as the improvement of quality standards of high-end plastic products for special purposes such as medicine and food, traditional polymer devolatilization technology can no longer meet the growing demand for devolatilization, and the development of new technologies is urgently needed.

[0003] Microwaves usually refer to electromagnetic waves with frequencies between 300MHz and 300GHz. They can be used as an efficient heat source to heat, dry, extract, sinter, and perform other operations on various materials. They are widely used in the chemical industry. Microwave heating technology is a technology that, under an external alternating electromagnetic field, polar molecules in a material are rapidly polarized and rubbed against each other, thereby converting electromagnetic energy into thermal energy and heating the material as a whole. Microwave heating belongs to the category of electric heating technology. Unlike traditional heating methods based on temperature difference heat transfer, conventional microwave heaters convert electrical energy into electromagnetic energy through a magnetron. The generated electromagnetic waves are transmitted to the microwave resonant cavity through a waveguide. The polar particles in the material undergo a dielectric response, converting the absorbed electromagnetic energy into thermal energy to achieve the purpose of heating the material.

[0004] When a polymer is heated by microwaves, the microwave energy absorbed by the polymer is converted into the heat energy of the polymer itself, which can achieve rapid and controllable heating of the material, uniform heating inside and outside, and effectively improve the production efficiency and product quality of polymer processing, and obtain a polymer product with weak odor and low volatile content. It has the advantages of simple method, high product quality, large processing volume, low energy consumption, etc., and is of great significance to the field of material processing such as high molecular polymer devolatilization. The prior art also discloses some methods of heating polymers by microwaves to remove small molecular substances in polymers, such as:

[0005] Patent application CN 102564074 A discloses a drying device and drying method for triglycidyl isocyanurate, which uses microwave heating to heat TGIC so that the methanol in TGIC is volatilized. During the heating period, the entire oven is in a negative pressure state, and the volatilized methanol gas enters the methanol recovery system. The characteristic of microwave selective heating of the product enables TGIC to be evenly heated during the drying process, solving the problems of material agglomeration and material agglomeration in traditional processes. The volatilized methanol gas is cooled by three condensers, and 95% of the methanol is recycled.

[0006] Patent application CN 114456555 A discloses a low-VOC polycaprolactone resin and a preparation method thereof, the preparation method comprising the following steps: pre-treating the polycaprolactone with a microwave vacuum two-stage devolatilizer, and then preparing the pre-treated polycaprolactone into pellets and blending and extruding the pellets with a processing aid; wherein the microwave vacuum two-stage devolatilizer pre-treatment step comprises: firstly performing vacuum heat treatment, the vacuum degree is above -0.05MPa, the treatment temperature is 30-55°C, and the treatment time is 10min-120min; then performing microwave heating, the heating time is 4-10min, the microwave power density is 10-50W / L, and the material gas-solid ratio is ≥4. The total volatile organic matter and odor of the polycaprolactone resin prepared by the preparation method can be significantly reduced, and it can be applied to fields such as high-end automotive interior parts, medical and food packaging materials with high environmental protection requirements.

[0007] However, the inventors of the present invention have found that the devolatilization methods used in the prior art are mostly multi-stage devolatilization technologies, and there are still few reports on devolatilization technologies that can achieve efficient removal of volatile components in polymers. Summary of the invention

[0008] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a method and device for removing volatiles from polymer particles and their application. The polymer obtained by the method of the present invention has the advantages of low volatile content, weak odor, good environmental protection and safety. The device of the present invention has a simple structure and is used to carry out devolatilization treatment on polymer particles with good devolatilization effect and high efficiency.

[0009] The purpose of the present invention is achieved through the following technical solutions:

[0010] In a first aspect, the present invention provides a method for removing volatiles from polymer particles, the method using a microwave fluidized bed to remove volatiles from polymer particles; the method specifically comprises using a microwave generator to heat the polymer particles entering a devolatilization chamber, and simultaneously introducing a fluidizing gas into the devolatilization chamber.

[0011] In some embodiments of the present invention, the temperature of the polymer particles in the devolatilization chamber is lower than the melting temperature and the pyrolysis temperature of the polymer particles.

[0012] In some embodiments of the present invention, the temperature of the polymer particles in the devolatilization chamber is higher than the volatilization temperature of at least one volatile component contained therein, but lower than the melting temperature and pyrolysis temperature of the polymer particles; at this temperature, the volatile components of the polymer particles can be effectively devolatilized without causing the polymer particles to melt or degrade. Preferably, the temperature of the polymer particles in the devolatilization chamber is higher than the volatilization temperature of the main volatile components contained therein, but lower than the melting temperature and pyrolysis temperature of the polymer particles. More preferably, the temperature of the polymer particles in the devolatilization chamber is higher than the volatilization temperature of all volatile components contained therein, but lower than the melting temperature and pyrolysis temperature of the polymer particles.

[0013] In some embodiments of the present invention, the superficial gas velocity of the fluidizing gas is greater than zero and less than the carrying-out velocity of the polymer particles; the polymer particles are in any of a fixed state, a fluidized state or other stationary state under the fluidizing gas, preferably a fluidized state.

[0014] In some embodiments of the present invention, the polymer particles are in a fluidized state under the fluidizing gas, and the fluidizing velocity of the fluidized material is 1 to 15 times the initial fluidizing velocity.

[0015] In some embodiments of the present invention, the average residence time of the polymer particles in the devolatilization chamber is 1 to 180 min, preferably 10 to 60 min; too short a residence time will result in poor devolatilization effect, while too long a residence time will result in material sticking to the wall and agglomeration.

[0016] In some embodiments of the present invention, the pressure in the devolatilization chamber is 0.001 to 1 MPa, preferably 0.001 to 0.1 MPa.

[0017] In some embodiments of the present invention, the temperature of the fluidizing gas is not lower than the feed temperature of the polymer particles, but lower than the melting temperature and pyrolysis temperature of the polymer particles.

[0018] In some embodiments of the present invention, the microwave power density in the devolatilization chamber is 10 to 1000 W / kg, preferably 100 to 500 W / kg; too low a microwave power density will affect the devolatilization effect of the material, and too high a microwave power density will lead to too high a heating temperature and too much energy loss.

[0019] In some embodiments of the present invention, the form of the polymer particles includes but is not limited to any one or more of powder, granules, and blocks, preferably powder; that is, under the premise of not affecting the normal use of the polymer particles, the smaller the size of the polymer particles, the better the devolatilization efficiency.

[0020] In some embodiments of the present invention, the polymer particles include polar polymer particles and / or non-polar polymer particles, and specific types include but are not limited to any one or more of plastic, rubber, and fiber. The polymer particles include but are not limited to any one or more of polyethylene, polypropylene, polybutene, and butadiene rubber.

[0021] In some embodiments of the present invention, the volatile matter includes water, gas, various volatile substances, etc.; the volatile matter mainly refers to volatile organic compounds, including any one or more of various polymerization monomers (such as ethylene, propylene, α-olefins, n-hexane, formaldehyde, acetone, etc.), solvents, condensing agents, etc. used in the polymer polymerization or further processing process.

[0022] In some embodiments of the present invention, the fluidizing gas includes but is not limited to any one or more of air, nitrogen, and helium, preferably nitrogen.

[0023] In some embodiments of the present invention, the flow mode of the fluidizing gas and the polymer particles is co-current and / or counter-current and / or cross-current, preferably counter-current.

[0024] In some embodiments of the present invention, the microwave heating method provided by the microwave generator is any one of intermittent heating, continuous heating and the like, preferably continuous heating.

[0025] In some embodiments of the present invention, the method further comprises adding additives into the devolatilization chamber; the types of the additives include but are not limited to microwave absorbers, devolatilization aids, antistatic agents, antioxidants, etc., which respectively play the role of improving microwave heating effect, improving material devolatilization efficiency, reducing static electricity accumulation, reducing material thermal oxidation degradation, etc.; preferably, the components of the additives include but are not limited to any one or more of water vapor, liquid water, supercritical carbon dioxide, low molecular hydrocarbons, and surfactants. More preferably, the low molecular hydrocarbons include but are not limited to any one or more of ethylene, propylene, propane, pentane, isopentane, and hexane. The surfactants include but are not limited to any one or more of stearic acid, sodium dodecylbenzene sulfonate, quaternary ammonium compounds, amino acid types, and fatty acid glycerides.

[0026] In some embodiments of the present invention, the percentage of the added mass of the additive to the feed mass of the polymer particles is 0 to 5%, preferably 0 to 1%.

[0027] In some embodiments of the present invention, the additives are added in ways including but not limited to:

[0028] (1) The additives are premixed with the polymer particles before entering the devolatilization chamber; preferably, the additives are mixed with the polymer particles in a premixing section before feeding the polymer particles or in a high-speed mixer, preferably in a high-speed mixer.

[0029] (2) The additive enters the devolatilization chamber from an additive feed port separately provided on the devolatilization chamber; preferably, the additive is gravity fed through the additive feed port or sprayed through a nozzle, preferably sprayed through a nozzle.

[0030] (3) The additive is mixed with the fluidizing gas and then enters the devolatilization chamber; preferably, the additive is premixed with the fluidizing gas and then enters the devolatilization chamber or is indirectly mixed with the fluidizing gas by the blowing force of the fluidizing gas and then enters the devolatilization chamber, preferably, the additive is premixed with the fluidizing gas and then enters the devolatilization chamber.

[0031] In some embodiments of the present invention, the total volatile content of the polymer particles before devolatilization treatment is greater than 100 μg·C / g, and the total volatile content after the treatment is less than 50 μg·C / g; preferably, the total volatile content before devolatilization treatment is greater than 1000 μg·C / g, and the total volatile content after the treatment is less than 30 μg·C / g.

[0032] In a second aspect, the present invention provides a device for removing volatile components from polymer particles, the device comprising a devolatilization chamber and a microwave generator, the microwave generator being capable of emitting microwaves into the devolatilization chamber; the devolatilization chamber being provided with a feed inlet and a discharge inlet, an air inlet and an air outlet.

[0033] In some embodiments of the present invention, a temperature measuring hole is provided on the wall of the devolatilization chamber and / or at the discharge port, and the temperature measuring method is preferably optical fiber temperature measurement, and the temperature of the material product is measured, and the microwave power is adjusted according to the temperature, which can prevent the material product from being melted and agglomerated due to excessive temperature.

[0034] In some embodiments of the present invention, a material level meter is provided in the devolatilization chamber, which can monitor the retention amount of polymer particles in real time and adjust the feeding and discharging speed according to the material level to prevent too much or too little material in the devolatilization chamber.

[0035] In some embodiments of the present invention, the operating parameters of the microwave generator are open-loop controlled or closed-loop controlled by a computer; preferably closed-loop control, which can control the microwave power in real time based on the material parameters including temperature and material level in the devolatilization chamber obtained by feedback.

[0036] In the following embodiment of the present invention, the feed port and the feed port, the air inlet and the air outlet of the devolatilization chamber are arranged so that the flow mode of the fluidizing gas and the polymer particles in the devolatilization chamber is co-current and / or counter-current and / or cross-current, preferably counter-current.

[0037] In some embodiments of the present invention, the devolatilization chamber is provided with a volatile matter detector, which can detect the concentration of volatile matter in the devolatilization chamber in real time, exhaust the waste gas in time, and ensure production safety.

[0038] In the following embodiment of the present invention, the device further comprises a gas distribution chamber, and the devolatilization chamber and the gas distribution chamber are integrated or independently arranged.

[0039] When the devolatilization chamber and the gas distribution chamber are integrated, the gas distribution chamber is arranged at a position inside the devolatilization chamber near the air inlet, and the indoor and outdoor spaces of the gas distribution chamber are separated by a gas distribution plate. The gas distribution plate is provided with air holes, and the air inlet of the devolatilization chamber is connected with the indoor space of the gas distribution chamber. The fluidizing gas first enters into the gas distribution chamber and then evenly enters into the outdoor space of the gas distribution chamber through the air holes on the gas distribution plate, so that the gas distribution inside the devolatilization chamber is more uniform.

[0040] When the devolatilization chamber and the gas distribution chamber are arranged independently of each other, the gas distribution chamber is arranged outside the devolatilization chamber and separated from the devolatilization chamber by a gas distribution plate, and an air inlet is arranged on the gas distribution chamber; air holes are opened on the gas distribution plate, and the air holes are equivalent to the air inlet of the devolatilization chamber; the fluidizing gas first enters the gas distribution chamber, and then evenly enters the devolatilization chamber through the air holes on the gas distribution plate between the gas distribution chamber and the devolatilization chamber.

[0041] In some embodiments of the present invention, the wall shape of the devolatilization chamber is a circular tube, a square tube, a polygonal tube and a combination thereof, preferably a circular tube. The wall shape should ensure the efficiency and uniformity of microwave reflection in the devolatilization chamber.

[0042] In some embodiments of the present invention, the wall of the devolatilization chamber is made of metal, preferably stainless steel, which can shield and reflect microwaves, thereby improving the efficiency of microwave heating of materials in the devolatilization chamber and the utilization rate of microwaves.

[0043] In some embodiments of the present invention, the microwave leakage value at 5 cm outside the wall of the devolatilization chamber is not greater than 5 mW / cm 2 , preferably not more than 3mW / cm 2 , which can ensure the safety of operators and the energy utilization of microwaves.

[0044] In some embodiments of the present invention, the wall seams of the devolatilization chamber are subjected to microwave sealing treatment to prevent microwave leakage and energy loss.

[0045] In the following embodiment of the present invention, the discharge port of the devolatilization chamber is far away from the feed port of the devolatilization chamber; for example, the feed port of the devolatilization chamber is arranged at the top of the devolatilization chamber, and the discharge port of the devolatilization chamber is arranged at the bottom of the devolatilization chamber; and for a tubular devolatilization chamber, the discharge port and feed port of the devolatilization chamber are respectively arranged at both ends of the tube.

[0046] In the following embodiments of the present invention, the air outlet of the devolatilization chamber is far away from the air inlet of the devolatilization chamber; for example, the air outlet of the devolatilization chamber is arranged at the top of the devolatilization chamber, and the air inlet of the devolatilization chamber is arranged at the bottom of the devolatilization chamber; and for a tubular devolatilization chamber, the air outlet and air inlet of the devolatilization chamber are respectively arranged at both ends of the tube.

[0047] In some embodiments of the present invention, a sealing partition is provided at the connection between the devolatilization chamber and the microwave generator for supporting materials and transmitting microwaves; the material of the sealing partition includes but is not limited to non-polar insulating materials such as polytetrafluoroethylene, polyethylene, polypropylene, etc., preferably polytetrafluoroethylene.

[0048] In some embodiments of the present invention, the devolatilization chamber is provided with one or more waveguide holes for installing a microwave generator and introducing microwaves.

[0049] In some embodiments of the present invention, the microwave generator comprises a magnetron, a waveguide, a switching power supply, a fan, etc. The waveguide of the microwave generator is fixed in the waveguide hole of the devolatilization chamber by flanges, bolts, gaskets, etc. The material of the gasket includes but is not limited to non-polar insulating materials such as polytetrafluoroethylene, polyethylene, and polypropylene, preferably polytetrafluoroethylene.

[0050] In some embodiments of the present invention, the waveguide holes of the devolatilization chamber and the microwave generator are evenly arranged to ensure that the microwave energy is evenly heated in the devolatilization chamber.

[0051] In some embodiments of the present invention, sampling holes are provided on the wall of the devolatilization chamber and / or at the discharge port to facilitate sampling of the material product for volatile content analysis or odor analysis.

[0052] In some embodiments of the present invention, the gas outlet of the devolatilization chamber is connected to a fan and an exhaust gas treatment system, so that the discharged volatile-containing gas flow can be separated, recovered or burned.

[0053] In some embodiments of the present invention, the feed port, the discharge port, the air inlet, the air outlet, the sampling hole, etc. of the devolatilization chamber are provided with a microwave shielding structure to ensure that no microwaves leak out when the material and the air flow enter and exit.

[0054] In some embodiments of the present invention, the device further comprises any one of the following arrangements for adding additives into the devolatilization chamber:

[0055] (1) The other end of the pipeline connected to the devolatilization chamber feed port is respectively connected to a polymer particle storage tank for providing polymer particles to be devolatilized and a storage tank for providing additives, or the other end of the pipeline connected to the devolatilization chamber air inlet is respectively connected to a gas supply tank for providing fluidizing gas and a storage tank for providing additives.

[0056] (2) The device also includes a high-speed mixer for premixing polymer particles and additives; the high-speed mixer is provided with a polymer particle feed port, an additive feed port, and a mixed material discharge port, wherein the mixed material discharge port is connected to the feed port of the devolatilization chamber, and the polymer particle feed port and the additive feed port can be independently provided or integrated.

[0057] (3) The device also includes a premixing chamber for premixing the fluidizing gas and the additive; the premixing chamber is provided with a fluidizing gas inlet, an additive feed inlet, and a mixed gas outlet, wherein the mixed gas outlet is connected to the air inlet of the devolatilization chamber, and the fluidizing gas inlet and the additive feed inlet can be independently provided or integrated.

[0058] (4) The devolatilization chamber is also provided with an additive feed port. Preferably, the additive feed port is in the shape of a nozzle, and / or the additive feed port is provided at the top of the devolatilization chamber.

[0059] In a third aspect, the present invention provides a method for removing volatilization from polymer particles using the device described in the second aspect.

[0060] In some embodiments of the present invention, the method includes: adding polymer particles to be devolatilized into a devolatilization chamber, emitting microwaves into the devolatilization chamber using a microwave generator to heat the polymer particles to be devolatilized, and simultaneously introducing a fluidizing gas into the devolatilization chamber.

[0061] In some embodiments of the present invention, the temperature of the polymer particles in the devolatilization chamber is lower than the melting temperature and the pyrolysis temperature of the polymer particles.

[0062] In some embodiments of the present invention, the temperature of the polymer particles in the devolatilization chamber is higher than the volatilization temperature of at least one volatile component contained therein, but lower than the melting temperature and pyrolysis temperature of the polymer particles. Preferably, the temperature of the polymer particles in the devolatilization chamber is higher than the volatilization temperature of the main volatile components contained therein, but lower than the melting temperature and pyrolysis temperature of the polymer particles. Most preferably, the temperature of the polymer particles in the devolatilization chamber is higher than the volatilization temperature of all volatile components contained therein, but lower than the melting temperature and pyrolysis temperature of the polymer particles.

[0063] In some embodiments of the present invention, the superficial gas velocity of the fluidizing gas is greater than zero and less than the carrying-out velocity of the polymer particles; the polymer particles are in any of a fixed state, a fluidized state or other stationary state under the fluidizing gas, preferably a fluidized state.

[0064] In some embodiments of the present invention, the polymer particles are in a fluidized state under the fluidizing gas, and the fluidizing velocity of the fluidized material is 1 to 15 times the initial fluidizing velocity.

[0065] In some embodiments of the present invention, the average residence time of the polymer particles in the devolatilization chamber is 1 to 180 min, preferably 10 to 60 min.

[0066] In some embodiments of the present invention, the pressure in the devolatilization chamber is 0.001 to 1 MPa, preferably 0.001 to 0.1 MPa.

[0067] In some embodiments of the present invention, the temperature of the fluidizing gas is not lower than the feed temperature of the polymer particles, but lower than the melting temperature and pyrolysis temperature of the polymer particles.

[0068] In some embodiments of the present invention, the microwave power density in the devolatilization chamber is 10 to 1000 W / kg, preferably 100 to 500 W / kg.

[0069] In some embodiments of the present invention, the fluidizing gas enters the gas distribution chamber from a gas inlet at the gas distribution chamber.

[0070] In some embodiments of the present invention, the method further comprises adding additives into the devolatilization chamber by means of a device for adding additives into the devolatilization chamber; the types of additives include, but are not limited to, microwave absorbers, devolatilization aids, antistatic agents, antioxidants, etc., which respectively play the role of improving microwave heating effect, improving material devolatilization efficiency, reducing static electricity accumulation, and reducing thermal oxidation degradation of materials. Preferably, the components of the additives include, but are not limited to, any one or more of water vapor, liquid water, supercritical carbon dioxide, low molecular hydrocarbons, and surfactants. More preferably, the low molecular hydrocarbons include, but are not limited to, any one or more of ethylene, propylene, propane, pentane, isopentane, and hexane. The surfactants include, but are not limited to, any one or more of stearic acid, sodium dodecylbenzene sulfonate, quaternary ammonium compounds, amino acid types, and fatty acid glycerides.

[0071] In some embodiments of the present invention, the percentage of the added mass of the additive to the feed mass of the polymer particles is 0 to 5%, preferably 0 to 1%.

[0072] In some embodiments of the present invention, the form of the polymer particles includes but is not limited to any one or more of powder, granules, and blocks, preferably powder; that is, under the premise of not affecting the normal use of the polymer particles, the smaller the size of the polymer particles, the better the devolatilization efficiency.

[0073] In some embodiments of the present invention, the polymer particles include polar polymer particles and / or non-polar polymer particles, and specific types include but are not limited to any one or more of plastic, rubber, and fiber. The polymer particles include but are not limited to any one or more of polyethylene, polypropylene, polybutene, and butadiene rubber.

[0074] In some embodiments of the present invention, the volatile matter includes water, gas, various volatile substances, etc.; the volatile matter mainly refers to volatile organic compounds, including any one or more of various polymerization monomers (such as ethylene, propylene, α-olefins, n-hexane, formaldehyde, acetone, etc.), solvents, condensing agents, etc. used in the polymer polymerization or further processing process.

[0075] In some embodiments of the present invention, the fluidizing gas includes but is not limited to any one or more of air, nitrogen, and helium, preferably nitrogen.

[0076] In some embodiments of the present invention, the microwave heating method provided by the microwave generator is any one of intermittent heating, continuous heating and the like, preferably continuous heating.

[0077] In some embodiments of the present invention, the total volatile content of the polymer particles before devolatilization treatment is greater than 100 μg·C / g, and the total volatile content after the treatment is less than 50 μg·C / g; preferably, the total volatile content before devolatilization treatment is greater than 1000 μg·C / g, and the total volatile content after the treatment is less than 30 μg·C / g.

[0078] In some embodiments of the present invention, the method may include using the apparatus described in the second aspect to implement the method described in the first aspect.

[0079] In a fourth aspect, the present invention provides use of the method described in the first aspect and / or the device described in the second aspect or the method described in the third aspect in removing volatiles from polymer particles.

[0080] The beneficial effects of the present invention are as follows:

[0081] The present invention provides a method for removing volatiles from polymer particles, the method comprising heating the polymer particles entering a devolatilization chamber by using a microwave generator, and heating the polymer particles by microwave heating. Compared with the traditional heating method, since the microwave energy absorbed by the polymer is converted into the heat energy of the polymer itself during microwave heating, the material can be quickly and controllably heated evenly inside and outside, and the production efficiency and product quality of polymer processing can be effectively improved, and a polymer product with weak odor and low volatile content can be obtained. The method has the advantages of simple method, high product quality, large processing volume, low energy consumption, etc., and is of great significance to the field of material processing such as high molecular polymer devolatilization. In addition, the method of the present invention introduces fluidizing gas into the devolatilization chamber while heating the material with microwaves, and the fluidizing gas can not only promote the rapid discharge of volatiles generated after heating; the fluidizing gas can also make the polymer particles in the devolatilization chamber fluidized, and the fluidized material can obtain more uniform heat, and can reduce the phenomenon of material sticking to the wall or agglomeration. The method of the present invention is used to devolatilize polymer particles, and it is not necessary to provide negative pressure conditions, and the pressure conditions of the devolatilization process are easier to meet; and the devolatilization efficiency is high, and the volatile matter in the polymer particles can be quickly and effectively removed in one stage of devolatilization, and even if the polymer particles with a total volatile matter content of more than 1000 μg·C / g are devolatilized, the removal rate can reach more than 97%. The polymer obtained by the method of the present invention has the advantages of low volatile matter content, weak odor, good environmental protection and safety.

[0082] The present invention also provides a device for removing volatiles from polymer particles. The main structure only includes a devolatilization chamber and a microwave generator. The structure is simple and the manufacturing cost is low. The device is used to carry out devolatilization treatment on polymers, and the devolatilization effect is good and the efficiency is high. In order to improve the devolatilization efficiency of the device, the device of the present invention is also provided with a gas distribution chamber, which can be used to evenly distribute the gas entering the devolatilization chamber to improve the heating uniformity of the material product. In order to improve the microwave utilization rate and safety of use of the device, the device of the present invention is also treated to prevent microwave leakage. The device of the present invention can be used for industrial production of removing volatiles from polymer particles, and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] Figure 1 A schematic diagram showing a device for removing volatile components from polymer particles provided by the present invention;

[0084] Figure 1 Identification of the icons in the figure: 1-devolatilization chamber, 1a-feed port, 1b-discharge port, 1c-gas outlet, 2-gas distribution chamber, 2a-gas inlet, 2b-gas distribution plate, 3-microwave generator, 3a-sealing partition.

[0085] Figure 2The figure shows the data results of the total volatile content and temperature change of the polymer particles when the volatile matter in the polymer particles is removed by the method of Example 1; the rising curve in the figure is the data result of the temperature change, and the falling curve is the data result of the total volatile content change.

[0086] Figure 3 The figure shows the data results of the total volatile content and temperature change of the polymer particles when the volatile matter in the polymer particles is removed by the method of Example 2; the rising curve in the figure is the data result of the temperature change, and the falling curve is the data result of the total volatile content change.

[0087] Figure 4 The figure shows the data results of the total volatile content and temperature change of the polymer particles when the volatile matter in the polymer particles is removed by the method of Example 3; the rising curve in the figure is the data result of the temperature change, and the falling curve is the data result of the total volatile content change.

[0088] Figure 5 The figure shows the data results of the total volatile content and temperature change of the polymer particles when the volatile matter in the polymer particles is removed by the method of Example 4; the rising curve in the figure is the data result of the temperature change, and the falling curve is the data result of the total volatile content change.

[0089] Figure 6 The figure shows the data results of the total volatile content and temperature change of the polymer particles when the volatile matter in the polymer particles is removed by the method of Example 5; the rising curve in the figure is the data result of the temperature change, and the falling curve is the data result of the total volatile content change.

[0090] Figure 7 It shows the data results of the total volatile content and temperature change of the polymer particles when the volatile matter in the polymer particles is removed by the method of Comparative Example 1; the rising curve in the figure is the data result of the temperature change, and the falling curve is the data result of the total volatile content change. DETAILED DESCRIPTION

[0091] The following examples further illustrate the technology of the present invention. These examples are for illustration and example of the present invention and are not intended to limit the scope of the present invention in any form.

[0092] The following combination Figure 1 The device and method provided by the present invention are described in detail.

[0093] Figure 1The device for removing volatiles from polymer particles provided by the present invention is shown, comprising a devolatilization chamber 1, a gas distribution chamber 2, and a microwave generator 3. The gas distribution chamber 2 is independently arranged at the bottom of the devolatilization chamber 1, and the devolatilization chamber 1 and the gas distribution chamber 2 are separated by a gas distribution plate 2b, and air holes are initially provided on the gas distribution plate 2b, and an air inlet 2a is provided on the side wall of the gas distribution chamber 2. The microwave generator 3 is arranged on the outer side wall of the devolatilization chamber 1, and a sealing partition 3a that can transmit microwaves is arranged between the devolatilization chamber 1 and the microwave generator 3. The devolatilization chamber 1 is also provided with a feed port 1a, a discharge port 1b, and an air outlet 1c; wherein the feed port 1a is arranged at the top of the devolatilization chamber 1; the air outlet 1c is arranged on the upper side wall of the devolatilization chamber 1, and the discharge port 1b is arranged on the lower side wall of the devolatilization chamber 1.

[0094] The components of microwave generator 3 include magnetron, waveguide, switching power supply, fan and so on.

[0095] Example 1

[0096] This embodiment adopts Figure 1 The apparatus shown devolatilizes polymer particles.

[0097] The main body of the devolatilization chamber is a vertical circular tube made of stainless steel, with a height of 540mm and an inner diameter of 350mm. There are 6 rectangular waveguide holes on the side wall of the devolatilization chamber, which are evenly arranged in two layers according to the height of the devolatilization chamber, with 3 holes in each layer, staggered at an angle of 120° on the same horizontal side wall, in order to make the microwave generator arrangement as dispersed as possible and improve the uniformity of microwave heating. The waveguides of the 6 microwave generators are fixed in the 6 rectangular waveguide holes of the devolatilization chamber through flanges, bolts, gaskets, etc., and the microwaves enter the devolatilization chamber through waveguide reflection; among them, the gasket for fixing the waveguide is a sealing gasket made of polytetrafluoroethylene, which is used to support the material and transmit the microwave. The operating frequency of the microwave generator is 2450MHz, using continuous wave continuous heating and open-loop control. The output power range of a single microwave generator is 250~1000W, which is continuously and infinitely adjustable, that is, the total microwave input power range is 250~6000W. Two temperature measuring holes are evenly arranged on the upper edge of the side wall of the devolatilization chamber, and an optical fiber temperature measuring probe is inserted to measure the working temperature in the devolatilization chamber. A volatile matter detector is arranged in the devolatilization chamber near the air outlet to perform real-time detection of the volatile matter concentration in the devolatilization chamber. Two sampling holes are evenly arranged on the upper edge of the side wall of the devolatilization chamber, and a sampling port is also arranged at the discharge port to measure the total volatile matter content of the polymer particles and perform product devolatilization performance detection. The air outlet of the devolatilization chamber is connected to the fan and the exhaust gas treatment system.

[0098] The polymer type is LLDPE powder, with an average particle size of 0.52 mm, a melting temperature of about 120°C, and a density of 0.908 kg / m 3. The type of additive is deionized water, the dosage is 0.2% of the polymer weight, and the mixing method is to pre-mix it with LLDPE powder in a high-speed mixer and then feed it into the devolatilization chamber through the feed port of the devolatilization chamber. The devolatilization process is an intermittent treatment, the single feeding amount is 10kg, the microwave power density is 250W / kg, and the residence time is 30min. The ambient temperature outside the devolatilization chamber is 25°C, and the working pressure of the devolatilization chamber is 0.1MPa. The fluidizing gas is air, which is in countercurrent contact with the polymer particles. The gas temperature is 25°C and the air inlet flow rate is 23m 3 / h; the superficial velocity of the fluidizing gas in the devolatilization chamber is 0.173m / s.

[0099] The data results of the total volatile content and temperature change of polymer particles are shown in the attached Figure 2 The total volatile content of the polymer particles is the data obtained by analyzing the sampling at the sampling port at the discharge port, and the temperature data of the polymer particles is the average value of the temperatures measured from the two temperature measuring holes.

[0100] Example 2

[0101] The only difference from Example 1 is that the fluidizing gas inlet flow rate is 65m 3 / h, the superficial velocity of the fluidizing gas in the devolatilization chamber is 0.225m / s. The data results of the total volatile content and temperature change of the polymer particles are shown in the attached Figure 3 .

[0102] Example 3

[0103] The only difference from Example 1 is that the fluidizing gas inlet flow rate is 80m 3 / h, the superficial velocity of the fluidizing gas in the devolatilization chamber is 0.276m / s. The data results of the total volatile content and temperature change of the polymer particles are shown in the attached Figure 4 .

[0104] Example 4

[0105] The only difference from Example 1 is that the fluidizing gas inlet flow rate is 95m 3 / h, the superficial velocity of the fluidizing gas in the devolatilization chamber is 0.328m / s. The data results of the total volatile content and temperature change of the polymer particles are shown in the attached Figure 5 .

[0106] Example 5

[0107] The only difference from Example 1 is that no additives are added. The data results of the total volatile content of the polymer particles and the temperature change are shown in the attached Figure 6 .

[0108] Comparative Example 1

[0109] The only difference from Example 1 is that no fluidizing gas is introduced into the devolatilization chamber (i.e., the fluidizing gas inlet flow rate is 0 m 3 / h). The data results of the total volatile content and temperature change of the polymer particles are shown in the attached Figure 7 .

[0110] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation of the present invention. The present invention has been described with reference to the embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein, on the contrary, the present invention can be extended to all other methods and applications with the same functions.

Claims

1. A method for removing volatiles from polymer particles, characterized in that: The method is to use a microwave fluidized bed to remove volatiles from polymer particles; the method specifically comprises using a microwave generator to heat the polymer particles entering a devolatilization chamber, and simultaneously introducing a fluidizing gas into the devolatilization chamber.

2. The method according to claim 1, characterized in that The temperature of the polymer particles in the devolatilization chamber is lower than the melting temperature and the pyrolysis temperature of the polymer particles; and / or The superficial velocity of the fluidizing gas is greater than zero and less than the carrying-out velocity of the polymer particles; the polymer particles are in any of a fixed state, a fluidized state or other stationary state under the fluidizing gas, preferably a fluidized state; more preferably, when the polymer particles are in a fluidized state under the fluidizing gas, the fluidizing velocity of the fluidized material is 1 to 15 times the initial fluidizing velocity.

3. The method according to claim 1 or 2, characterized in that: The average residence time of the polymer particles in the devolatilization chamber is 1 to 180 min, preferably 10 to 60 min; and / or The pressure in the devolatilization chamber is 0.001 to 1 MPa, preferably 0.001 to 0.1 MPa; and / or The temperature of the fluidizing gas is not lower than the feed temperature of the polymer particles, but lower than the melting temperature and pyrolysis temperature of the polymer particles; and / or The microwave power density in the devolatilization chamber is 10 to 1000 W / kg, preferably 100 to 500 W / kg; and / or The fluidizing gas and the polymer particles flow in a co-current and / or counter-current and / or cross-current manner, preferably a counter-current manner; and / or The microwave heating method provided by the microwave generator is any one of intermittent heating and continuous heating, preferably continuous heating.

4. The method according to any one of claims 1 to 3, characterized in that: The method further comprises adding additives into the devolatilization chamber, wherein the types of the additives include microwave absorbers, devolatilization aids, antistatic agents, and antioxidants; preferably, the components of the additives include any one or more of water vapor, liquid water, supercritical carbon dioxide, low molecular weight hydrocarbons, and surfactants; more preferably, the percentage of the added mass of the additives to the feed mass of the polymer particles is 0 to 5%, preferably 0 to 1%; further preferably, the addition method of the additives includes any one or more of the following: (1) The additives are premixed with the polymer particles and then enter the devolatilization chamber; preferably, the additives are mixed with the polymer particles in a premixing section before the polymer particles are fed or in a high-speed mixer, preferably in a high-speed mixer; (2) the additive enters the devolatilization chamber from an additive feed port separately provided on the devolatilization chamber; preferably, the additive is gravity fed through the additive feed port or sprayed through a nozzle, preferably sprayed through a nozzle; (3) The additive is mixed with the fluidizing gas and then enters the devolatilization chamber; preferably, the additive is premixed with the fluidizing gas and then enters the devolatilization chamber or is indirectly mixed with the fluidizing gas by the blowing force of the fluidizing gas and then enters the devolatilization chamber, preferably, the additive is premixed with the fluidizing gas and then enters the devolatilization chamber.

5. The method according to any one of claims 1 to 4, characterized in that: The polymer particles may be in the form of any one or more of powder, granules, and blocks, preferably powder; and / or The polymer particles include polar polymer particles and / or non-polar polymer particles, preferably include any one or more of plastic, rubber, and fiber, and more preferably include any one or more of polyethylene, polypropylene, polybutene, and butadiene rubber; and / or The volatile matter includes water, gas, and various volatile substances; preferably, the volatile matter mainly refers to volatile organic compounds, including any one or more of various polymerization monomers, solvents, and condensing agents used in the polymerization or further processing of polymers; more preferably, the polymerization monomers include any one or more of ethylene, propylene, α-olefins, n-hexane, formaldehyde, and acetone; and / or The fluidizing gas includes any one or more of air, nitrogen and helium, preferably nitrogen.

6. A device for removing volatiles from polymer particles, characterized in that: The device comprises a devolatilization chamber and a microwave generator, wherein the microwave generator can emit microwaves into the devolatilization chamber; and the devolatilization chamber is provided with a feed inlet and a discharge inlet, an air inlet and an air outlet.

7. The device according to claim 6, characterized in that A temperature measuring hole is provided on the wall of the devolatilization chamber and / or at the discharge port, and the temperature measuring method is preferably optical fiber temperature measurement; and / or The devolatilization chamber is provided with a material level meter, which can monitor the retention amount of polymer particles in real time; and / or The working parameters of the microwave generator are controlled by a computer in an open loop or closed loop; preferably in a closed loop, and the microwave power can be controlled in real time according to the material parameters including temperature and material level in the devolatilization chamber obtained by feedback; and / or, The feed inlet and the discharge inlet, the air inlet and the air outlet of the devolatilization chamber are arranged so that the flow of the fluidizing gas and the polymer particles in the devolatilization chamber is co-current and / or counter-current and / or cross-current, preferably counter-current; and / or, The devolatilization chamber is provided with a volatile matter detector, which can detect the concentration of volatile matter in the devolatilization chamber in real time; and / or, The devolatilization chamber wall and / or the discharge port are provided with sampling holes; and / or, The air outlet of the devolatilization chamber is connected to a fan and an exhaust gas treatment system.

8. The device according to claim 6 or 7, characterized in that The device further comprises a gas distribution chamber, and the devolatilization chamber and the gas distribution chamber are integrated or independently arranged; preferably, When the devolatilization chamber and the gas distribution chamber are integrated, the gas distribution chamber is arranged in the devolatilization chamber near the air inlet, the indoor and outdoor spaces of the gas distribution chamber are separated by a gas distribution plate, and air holes are provided on the gas distribution plate. The air inlet of the devolatilization chamber is connected with the indoor space of the gas distribution chamber, and the fluidizing gas first enters the indoor space of the gas distribution chamber and then evenly enters the outdoor space of the gas distribution chamber through the air holes on the gas distribution plate; When the devolatilization chamber and the gas distribution chamber are arranged independently of each other, the gas distribution chamber is arranged outside the devolatilization chamber and separated from the devolatilization chamber by a gas distribution plate, and an air inlet is arranged on the gas distribution chamber; air holes are opened on the gas distribution plate, and the air holes are equivalent to the air inlet of the devolatilization chamber; the fluidizing gas first enters the gas distribution chamber, and then evenly enters the devolatilization chamber through the air holes on the gas distribution plate between the gas distribution chamber and the devolatilization chamber.

9. The device according to any one of claims 6 to 8, characterized in that The device also includes any one of the following arrangements for adding additives into the devolatilization chamber: (1) The other end of the pipeline connected to the devolatilization chamber feed port is respectively connected to a polymer particle storage tank for providing polymer particles to be devolatilized and a storage tank for providing additives, or the other end of the pipeline connected to the devolatilization chamber air inlet is respectively connected to a gas supply tank for providing fluidizing gas and a storage tank for providing additives; (2) The device further comprises a high-speed mixer for premixing polymer particles and additives; the high-speed mixer is provided with a polymer particle feed port, an additive feed port, and a mixed material discharge port, wherein the mixed material discharge port is connected to the feed port of the devolatilization chamber, and the polymer particle feed port and the additive feed port can be independently provided or integrally provided; (3) The device further comprises a premixing chamber for premixing the fluidizing gas and the additive; the premixing chamber is provided with a fluidizing gas inlet, an additive feed inlet, and a mixed gas outlet, wherein the mixed gas outlet is connected to the gas inlet of the devolatilization chamber, and the fluidizing gas inlet and the additive feed inlet can be provided separately or integrally; (4) The devolatilization chamber is also provided with an additive feed port. Preferably, the additive feed port is in the shape of a nozzle, and / or the additive feed port is provided at the top of the devolatilization chamber.

10. The device according to any one of claims 6 to 9, characterized in that: The microwave generator comprises a magnetron, a waveguide, a switching power supply, and a fan; preferably, one or more waveguide holes are provided on the devolatilization chamber for installing the microwave generator and introducing microwaves; more preferably, the waveguide of the microwave generator is fixed in the waveguide hole of the devolatilization chamber by a flange, bolts, and a gasket; further preferably, the waveguide hole of the devolatilization chamber and the microwave generator are evenly arranged; and / or A sealing baffle is provided at the connection between the devolatilization chamber and the microwave generator for supporting the material and transmitting the microwave; preferably, the sealing baffle is made of a non-polar insulating material; more preferably, the sealing baffle is made of any one or more of polytetrafluoroethylene, polyethylene, and polypropylene, preferably polytetrafluoroethylene; and / or The wall shape of the devolatilization chamber is a round tube, a square tube, a polygonal tube and a combination thereof, preferably a round tube; and / or The wall of the devolatilization chamber is made of metal, preferably stainless steel; and / or The microwave leakage value at 5 cm outside the wall of the devolatilization chamber is not greater than 5 mW / cm 2 , preferably not more than 3mW / cm 2 ; and / or The wall seams of the devolatilization chamber are microwave sealed; and / or The feed inlet, the discharge port, the air inlet, the air outlet and the sampling hole of the devolatilization chamber are provided with a microwave shielding structure.

11. A method for devolatile polymer particles using the apparatus according to any one of claims 6 to 10, preferably comprising using the apparatus to implement the method according to any one of claims 1 to 5.

12. Use of the method according to any one of claims 1 to 5 and / or the device according to any one of claims 6 to 10 or the method according to claim 11 in devolatile matter removal from polymer particles.

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