Method for reducing dissolved oxygen in MMA raw material solution, MMA raw material solution and application of MMA raw material solution

Abstract

The invention relates to a method for reducing dissolved oxygen in an MMA raw material solution, the MMA raw material solution and application of the MMA raw material solution, and the method comprises the following steps: (1) mixing the MMA raw material solution with nitrogen for gas replacement treatment to obtain a mixed MMA raw material solution; (2) decompressing and degassing the mixed MMA raw material liquid obtained in the step (1) to obtain mixed gas and MMA raw material liquid with low dissolved oxygen; and (3) sequentially pressurizing, condensing and separating the mixed gas obtained in the step (2) to realize separation of nitrogen, oxygen and the MMA raw material liquid. According to the method, the dissolved oxygen in the MMA raw material solution can be removed to 0.1 ppm or below, the polymerization reaction is completed by adopting a conventional polymerization process, and the PMMA material with excellent performance can be obtained.

Description

Technical Field

[0001] The invention relates to the technical field of PMMA synthesis, and in particular to a method for reducing dissolved oxygen in MMA raw material liquid, the MMA raw material liquid and applications thereof. Background Art

[0002] The chemical name of PMMA is polymethyl methacrylate, commonly known as acrylic or plexiglass. It has the characteristics of high surface hardness, good dimensional stability and good electrical insulation. It is currently widely used in automobiles, displays, electronic appliances, lighting, billboards and other fields.

[0003] The polymerization methods of PMMA mainly include solution polymerization and bulk polymerization. Both methods require the use of MMA monomer as a raw material for polymerization. Oxygen is required as an inhibitor before polymerization to prevent the formation of oligomers from entering the polymerization stage and affecting the molecular weight distribution of the overall polymerization reaction. Therefore, dissolved oxygen will exist in the MMA raw material solution. Usually, the dissolved oxygen content in the raw material solution is too high, which will reduce the viscosity of the polymerization product, thereby affecting the application properties of the obtained polymer product, such as thermal stability, weather resistance, and transparency.

[0004] In the existing process, the oxygen content in the MMA raw material liquid can be generally reduced to 5-10 ppm by stripping the dissolved oxygen in the MMA raw material liquid with inert gas in a vertical tower or container. However, CN1303397A states that "if the dissolved oxygen content is greater than 2 ppm, not only will the polymerization reaction be unstable, but also colored components may be easily formed in the polymerization step where the reactor mixture is kept at a high temperature for a long time", so the oxygen content in the MMA raw material liquid obtained by the existing process is still relatively high.

[0005] CN104492125A discloses a method for removing dissolved oxygen from a viscous liquid, comprising the following steps: placing a sample bottle filled with viscous liquid in a vacuum dryer, the higher the viscosity of the liquid, the longer the vacuum time; after vacuuming, connecting the vacuum dryer to high-purity nitrogen, opening the valve connecting the high-purity nitrogen bottle and the vacuum dryer, and raising the negative pressure in the vacuum dryer to atmospheric pressure; then placing the sample bottle containing the viscous liquid in an anaerobic glove box for secondary deoxygenation; finally, sealing the sample bottle with a rubber stopper and an aluminum cap to complete the deoxygenation process. This method uses an anaerobic glove box to remove dissolved oxygen from a polymer solution, but due to the high viscosity of the polymer solution, it is difficult for the glove box to extract the dissolved oxygen therein, and the glove box is not commonly used, and the operation is also relatively cumbersome. Summary of the invention

[0006] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for reducing dissolved oxygen in MMA raw material liquid, MMA raw material liquid and application thereof, which can remove dissolved oxygen in MMA raw material liquid to below 0.1 ppm, and use conventional polymerization process to complete the polymerization reaction to obtain PMMA material with excellent performance.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a method for reducing dissolved oxygen in an MMA raw material solution, the method comprising the following steps:

[0009] (1) Mixing the MMA raw material liquid with nitrogen and performing gas replacement treatment to obtain a mixed MMA raw material liquid;

[0010] (2) subjecting the mixed MMA raw material liquid obtained in step (1) to a decompression degassing treatment to obtain a mixed gas and an MMA raw material liquid with low dissolved oxygen;

[0011] (3) The mixed gas obtained in step (2) is pressurized, condensed and separated in sequence to separate nitrogen, oxygen and MMA raw material liquid.

[0012] The method for reducing dissolved oxygen in an MMA raw material liquid provided by the present invention comprises the following steps: firstly, the MMA raw material liquid is subjected to a gas replacement treatment, during which nitrogen is fully mixed into the MMA raw material liquid, which is helpful for removing dissolved oxygen; the treated MMA raw material liquid is subjected to a decompression degassing treatment, during which the solubility of the gas is reduced, and dissolved oxygen escapes from the MMA raw material liquid together with nitrogen, and the dissolved oxygen remaining in the MMA raw material liquid is further removed to obtain an MMA raw material liquid with low dissolved oxygen; in the subsequent polymerization reaction, oxygen-induced MMA polymerization reaction products can be reduced, and the obtained PMMA material has the characteristics of strong thermal stability, good weather resistance, high transparency, etc., and can be expanded for application in occasions with higher standards.

[0013] It should be noted that the "gas replacement treatment" and "decompression degassing treatment" described in the present invention refer to the process of replacing dissolved oxygen from the MMA raw material solution with nitrogen and removing the dissolved oxygen under reduced pressure.

[0014] Preferably, the temperature of the gas replacement treatment in step (1) is between -10°C and 45°C, and the pressure is greater than 2.5 MPaG.

[0015] The temperature of the gas replacement treatment is -10°C to 45°C, for example, it can be -10°C, 10°C, 20°C, 25°C, 30°C, 35°C, 40°C or 45°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0016] The pressure of the gas replacement treatment is greater than 2.5 MPaG, for example, it can be 2.8 MPaG, 3 MPaG, 3.5 MPaG, 4 MPaG, 4.5 MPaG or 5 MPaG, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable, preferably 3-4.5 MPaG.

[0017] Preferably, the pressure of the reduced pressure degassing treatment in step (2) is 0.102-0.105 MPaG, for example, it can be 0.102 MPaG, 0.103 MPaG, 0.104 MPaG or 0.105 MPaG, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0018] When the pressure increases, the solubility of the gas will increase; when the pressure decreases, the solubility of the gas will decrease. Based on the conditions of temperature -10°C and pressure 2.5MPaG, the amount of nitrogen dissolved is about 1wt%. It has been found through research that when the nitrogen dissolved in the solution is greater than 1wt%, and the gas phase nitrogen and the liquid phase are evenly mixed, the dissolved oxygen removal rate is high. However, considering the energy consumption and equipment investment cost, the pressure condition should not be greater than 5MPaG. Therefore, the present invention performs gas replacement treatment and decompression degassing treatment on the MMA raw material liquid in a medium pressure environment.

[0019] Preferably, the pressure of the supercharged mixed gas in step (3) is greater than 2.6 MPaG, for example, it can be 2.8 MPaG, 3.1 MPaG, 3.5 MPaG, 4.6 MPaG or 5 MPaG, but is not limited to the listed values. Other values ​​not listed in the numerical range are also applicable, preferably 3.1-4.6 MPaG.

[0020] Preferably, the condensation temperature in step (3) is -10°C to 40°C, for example, -10°C, 0°C, 10°C, 20°C, 25°C, 30°C or 40°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0021] The MMA raw material liquid produced after the condensation in step (3) is recycled and used in the gas replacement process.

[0022] Preferably, the separation in step (3) comprises membrane separation, and the membrane used for membrane separation is a membrane with an oxygen permeation rate greater than the nitrogen and MMA permeation rates.

[0023] The material of the membrane used for membrane separation includes polyimide or polysulfone.

[0024] After the membrane separation, oxygen-rich gas and nitrogen-rich gas are obtained, and the nitrogen-rich gas is recycled and used in the gas replacement process.

[0025] In the method provided by the present invention, the mixed gas is pressurized and condensed, and the MMA raw material liquid in the gas can be condensed and then transported to the gas replacement treatment, and the loss of the MMA raw material liquid is reduced by recycling; the mixed gas enters the membrane separation, and on the one hand, a membrane with an oxygen permeability greater than that of nitrogen and MMA is selected, so that oxygen can be effectively separated from the mixed gas; on the other hand, due to the fast permeability of oxygen, oxygen preferentially passes through the membrane and enters the downstream side of the membrane to become oxygen-rich gas; the nitrogen permeability is slow, so it is retained on the upstream side of the membrane to become nitrogen-rich gas, which not only separates the nitrogen for recycling and reduces the loss of nitrogen, but also increases the oxygen concentration, which is beneficial to reducing the energy consumption of downstream gas processing equipment.

[0026] Preferably, the method is carried out in a device system for reducing dissolved oxygen in MMA raw material liquid, the device system includes a booster pump, a mixing device, a pressure reducing valve and a degassing device which are sequentially connected along the material flow direction, the top of the degassing device is sequentially connected to a compressor, a condenser and a membrane separation device, and the bottom of the degassing device discharges MMA raw material liquid with low dissolved oxygen; a nitrogen inlet pipeline is connected between the booster pump and the mixing device.

[0027] The MMA raw material liquid discharged from the condenser is recycled and used in the mixing device.

[0028] The nitrogen-rich gas discharged from the membrane separation device is recycled back to the mixing device.

[0029] It should be noted that internal parts can be set in the degassing device, which is suitable for MMA raw material liquid containing different inhibitors, and can remove other impurities such as free acid, inhibitor, free metal ions, etc., which may affect the quality of PMMA while removing dissolved oxygen; the internal parts can preferably be ion exchange resins, but are not limited to this.

[0030] As a preferred technical solution of the method of the present invention, the method comprises the following steps:

[0031] (1) The MMA raw material liquid is pumped into a mixing device with a pressure greater than 2.5 MPaG through a booster pump, and nitrogen is introduced through a nitrogen inlet pipeline, and mixed at -10°C to 45°C for gas replacement treatment to obtain a mixed MMA raw material liquid;

[0032] (2) The mixed MMA raw material liquid obtained in step (1) is decompressed to 0.102-0.105 MPaG through a pressure reducing valve and then sent to a degassing device for decompression and degassing to obtain a mixed gas and a MMA raw material liquid with low dissolved oxygen;

[0033] (3) The mixed gas obtained in step (2) is pressurized to a level greater than 2.6 MPaG by a compressor and condensed by a condenser at a temperature of -10°C to 40°C. The generated MMA raw liquid is recycled back to the mixing device for gas replacement treatment. The mixed gas is then separated by a membrane separation device to obtain oxygen-rich gas and nitrogen-rich gas. The obtained nitrogen-rich gas is recycled back to the mixing device for gas replacement treatment, thereby achieving separation of nitrogen, oxygen and MMA raw liquid.

[0034] In a second aspect, the present invention provides a low dissolved oxygen MMA raw material solution, wherein the MMA raw material solution is obtained by processing the method described in the first aspect.

[0035] Preferably, the oxygen content of the MMA raw material solution is ≤0.1 ppm, for example, it may be 0.1 ppm, 0.08 ppm, 0.05 ppm, 0.03 ppm or 0.01 ppm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0036] The MMA raw material liquid provided by the present invention has the characteristic of low dissolved oxygen. When a subsequent polymerization reaction is carried out, oxygen-induced MMA polymerization products can be reduced, thereby obtaining a PMMA material with strong thermal stability, good weather resistance and high transparency.

[0037] In a third aspect, the present invention provides an application of the MMA raw material liquid with low dissolved oxygen as described in the second aspect, and the PMMA material obtained by polymerization of the MMA raw material liquid is used in electronic equipment, aerospace and medical fields.

[0038] The MMA raw material liquid enters the downstream section to complete polymerization and extrusion granulation to obtain PMMA material, which can be used in electronic equipment, aerospace and medical fields.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] (1) The method for reducing dissolved oxygen in MMA raw material liquid provided by the present invention first performs gas replacement treatment on the MMA raw material liquid. During this process, nitrogen is fully mixed into the MMA raw material liquid, which helps to remove dissolved oxygen. The treated MMA raw material liquid is subjected to decompression degassing treatment. During the decompression process, the solubility of the gas is reduced, and the dissolved oxygen escapes from the MMA raw material liquid together with the nitrogen, and the dissolved oxygen remaining in the MMA raw material liquid is further removed, thereby obtaining a low-dissolved-oxygen MMA raw material liquid. When a subsequent polymerization reaction is carried out, oxygen-induced MMA polymerization reaction products can be reduced. The obtained PMMA material has the characteristics of strong thermal stability, good weather resistance, high transparency, etc., and can be expanded to applications in higher standard occasions.

[0041] (2) The method for reducing dissolved oxygen in MMA raw material liquid provided by the present invention can separate the MMA raw material liquid and nitrogen in the gas for recycling, thereby reducing material loss and facilitating energy saving and efficiency improvement. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 1 is a schematic diagram of the structure of a device system for reducing dissolved oxygen in an MMA raw material solution provided in Example 1 of the present invention;

[0043] Figure 2 It is a schematic structural diagram of a device system for reducing dissolved oxygen in an MMA raw material solution provided in Comparative Example 1 of the present invention;

[0044] Figure 3 It is a schematic diagram of the structure of the mixing device system provided in Comparative Example 2 of the present invention.

[0045] Among them: 1, booster pump; 2, mixing device; 3, pressure reducing valve; 4, degassing device; 5, compressor; 6, condenser; 7, membrane separation device; 8, degassing tower; 9, cooler; 10, oxygen analyzer. DETAILED DESCRIPTION

[0046] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0047] Example 1

[0048] This embodiment provides a method for reducing dissolved oxygen in MMA raw material liquid. The method is carried out in a device system for reducing dissolved oxygen in MMA raw material liquid. The structural schematic diagram is shown in FIG. Figure 1 As shown, the method comprises the following steps:

[0049] (1) The MMA raw material liquid is pumped into a mixing device 2 at a pressure of 3 MPaG by a booster pump 1, and nitrogen is introduced from a nitrogen inlet pipeline at the same time, and mixed at 30° C. for gas replacement treatment to obtain a mixed MMA raw material liquid;

[0050] (2) The mixed MMA raw material liquid obtained in step (1) is decompressed to 0.103 MPaG through a pressure reducing valve 3 and then sent to a degassing device 4 for decompression and degassing to obtain a mixed gas and an MMA raw material liquid with low dissolved oxygen;

[0051] (3) The mixed gas obtained in step (2) is pressurized to 3.5 MPaG by a compressor 5 and condensed by a condenser 6 at 10° C. The generated MMA raw liquid is circulated back to the mixing device 2 for gas replacement treatment; then, it is separated by a membrane separation device 7 to obtain oxygen-rich gas, nitrogen-rich gas and waste gas, and the waste gas is discharged for treatment. The nitrogen-rich gas is circulated back to the mixing device 2 for gas replacement treatment, thereby achieving separation of nitrogen, oxygen and MMA raw liquid.

[0052] The MMA raw material liquid with low dissolved oxygen obtained in step (2) enters the downstream process section after being tested by the oxygen analyzer 10 and found to be qualified, and the PMMA material is obtained through polymerization reaction and extrusion granulation.

[0053] Example 2

[0054] This embodiment provides a method for reducing dissolved oxygen in an MMA raw material solution. The difference from Embodiment 1 is that the pressure of the reduced pressure in step (2) is adjusted to 0.102 MPaG, the pressure of the increased pressure in step (3) is adjusted to 3.1 MPaG, and the temperature of the process side of the condenser 6 is adjusted to -10°C. The rest is the same as Embodiment 1.

[0055] Example 3

[0056] This embodiment provides a method for reducing dissolved oxygen in an MMA raw material solution. The difference from Embodiment 1 is that the pressure of the reduced pressure in step (2) is adjusted to 0.105 MPaG, the pressure of the increased pressure in step (3) is adjusted to 4.6 MPaG, and the temperature of the process side of the condenser 6 is adjusted to 25° C. The rest is the same as Embodiment 1.

[0057] Example 4

[0058] This embodiment provides a method for reducing dissolved oxygen in MMA raw material liquid. The difference from Embodiment 1 is that the pressure of the mixing device 2 in step (1) is adjusted to 3.5 MPaG, and the rest is the same as Embodiment 1.

[0059] Example 5

[0060] This embodiment provides a method for reducing dissolved oxygen in MMA raw material liquid. The difference from Embodiment 1 is that the pressure of the mixing device 2 in step (1) is adjusted to 4.5 MPaG, and the rest is the same as Embodiment 1.

[0061] Example 6

[0062] This embodiment provides a method for reducing dissolved oxygen in MMA raw material liquid. The difference from Embodiment 1 is that the pressure of the mixing device 2 in step (1) is adjusted to 5 MPaG, and the rest is the same as Embodiment 1.

[0063] Example 7

[0064] This embodiment provides a method for reducing dissolved oxygen in MMA raw material liquid. The difference from Embodiment 1 is that the pressure of the mixing device 2 in step (1) is adjusted to 2.5 MPaG, and the rest is the same as Embodiment 1.

[0065] Example 8

[0066] This embodiment provides a method for reducing dissolved oxygen in MMA raw material solution. The difference from Embodiment 4 is that the temperature of the gas replacement treatment in step (1) is adjusted to 20° C., and the rest is the same as Embodiment 4.

[0067] Example 9

[0068] This embodiment provides a method for reducing dissolved oxygen in MMA raw material solution. The difference from Embodiment 4 is that the temperature of the gas replacement treatment in step (1) is adjusted to 25° C., and the rest is the same as Embodiment 4.

[0069] Example 10

[0070] This embodiment provides a method for reducing dissolved oxygen in MMA raw material solution. The difference from Embodiment 4 is that the temperature of the gas replacement treatment in step (1) is adjusted to 35° C., and the rest is the same as Embodiment 4.

[0071] Embodiment 11

[0072] This embodiment provides a method for reducing dissolved oxygen in MMA raw material solution. The difference from Embodiment 4 is that the temperature of the gas replacement treatment in step (1) is adjusted to 40° C., and the rest is the same as Embodiment 4.

[0073] Example 12

[0074] This embodiment provides a method for reducing dissolved oxygen in MMA raw material solution. The difference from Embodiment 4 is that the temperature of the gas replacement treatment in step (1) is adjusted to -10°C, and the rest is the same as Embodiment 4.

[0075] Example 13

[0076] This embodiment provides a method for reducing dissolved oxygen in MMA raw material liquid. The difference from Embodiment 4 is that the temperature of the gas replacement treatment in step (1) is adjusted to 45° C., and the rest is the same as Embodiment 4.

[0077] Embodiment 14

[0078] This embodiment provides a method for reducing dissolved oxygen in an MMA raw material solution. The difference from Embodiment 1 is that the pressure of the pressurization in step (3) is adjusted to 2.6 MPaG, and the rest is the same as Embodiment 1.

[0079] Comparative Example 1

[0080] This comparative example provides a method for reducing dissolved oxygen in MMA raw material liquid, wherein the method uses inert gas to strip dissolved oxygen in MMA raw material liquid in a vertical tower or container. The structural schematic diagram of the device system is shown in FIG. Figure 2 As shown, the specific steps include:

[0081] (1) The MMA raw material liquid at 15°C and 0.3MPaG is introduced into the degassing tower 8, and nitrogen at 25°C and 0.1MPaG is introduced into the degassing tower 8 at the same time. The operating conditions of the degassing tower 8 are 15°C and ATM. After the stripping and degassing treatment, the oxygen content of the MMA raw material liquid can reach 5-10ppm;

[0082] (2) The gas at the top of the degassing tower 8 is cooled by the cooler 9 and then discharged into the exhaust gas system;

[0083] (3) The treated MMA raw material liquid enters the downstream process section after being tested by an oxygen analyzer 10 to be qualified, and the polymerization reaction is completed by a conventional polymerization process, and the PMMA material is obtained by extrusion granulation.

[0084] Comparative Example 2

[0085] This comparative example provides a method for reducing dissolved oxygen in MMA raw material liquid, and the method is carried out using a mixing device system, and the structural schematic diagram is shown in FIG. Figure 3 As shown, the difference from Example 4 is that there is no step (2) and step (3), and the rest is the same as Example 4.

[0086] The oxygen content and nitrogen content of the MMA raw material solutions provided in Examples 1-14 and Comparative Examples 1 and 2 and the MMA raw material solution with low dissolved oxygen were tested by an oxygen content tester and a nitrogen detector, and the results are shown in Table 1.

[0087] Table 1

[0088]

[0089] From the data in Table 1, we can see that:

[0090] (1) At the same operating temperature, the effect of pressure change on the oxygen content in MMA is small; when the operating temperature is 30°C, the operating pressure is changed, and the oxygen content in the MMA solution obtained after treatment is close to 0.1ppm, which shows that the method of the present invention is applicable to a variety of pressure conditions and can reduce the difficulty of equipment selection. However, from the perspective of energy consumption and equipment investment cost, the pressure condition should not be greater than 5MPaG. Comparing Example 1 with Example 7, it is shown that the pressure should not be too low, which will lead to a decrease in gas solubility and a decrease in dissolved oxygen removal rate. Comparing Example 1 with Example 14, it is shown that in the separation stage, if the boost pressure is too low, the oxygen permeation will also decrease. Oxygen continues to circulate with the circulating nitrogen, increasing the load of downstream equipment and increasing the dissolved oxygen content.

[0091] (2) Comparing Example 1 with Examples 8-13, under the same operating pressure, the higher the temperature, the better the deoxygenation effect, and the oxygen content in the MMA solution is below 0.1 ppm; on the other hand, it should be considered that too high a temperature can easily induce a polymerization reaction in the MMA solution. Therefore, gas replacement treatment within a reasonable temperature range can not only prevent the polymerization reaction of the MMA solution, but also reduce the oxygen content in the MMA solution to below 0.1 ppm, which greatly improves the performance of the PMMA material obtained after treatment.

[0092] (3) It can be concluded from Comparative Example 1 that the oxygen content of the MMA solution after deoxygenation treatment by the method of the present invention is much lower than the oxygen content after treatment by the existing process.

[0093] Selecting examples with the same operating pressure and different operating temperatures, the PMMA materials obtained in Examples 4, 8, 11 and Comparative Examples 1 and 2 were tested for yellowing index by a yellowness tester. The results are shown in Table 2, and the yellowing index table is shown in Table 3. It can be seen from the data in Tables 2 and 3 that:

[0094] The lower the oxygen content of the MMA raw material liquid during the polymerization reaction, the lower the yellowing index of the PMMA material obtained, which means that the transparency of the PMMA material is better.

[0095] By comparing the data of Examples 4, 8, and 11 with those of Comparative Examples 1 and 2, it can be reflected that the yellowing index of the PMMA material obtained by polymerization of the MMA raw material solution provided by the present invention is lower than the yellowing index of the PMMA material obtained by polymerization of the MMA raw material solution of Comparative Examples 1 and 2; by comparing the PMMA yellowing index of Examples 4, 8, and 11, it can be reflected that when the oxygen content in the MMA raw material solution has a slight change, the yellowing index of PMMA also has obvious fluctuations, and the lower the oxygen content, the lower the yellowing index of the PMMA material obtained.

[0096] The lower the oxygen content during the polymerization reaction, the more beneficial it is to the improvement of the performance of the PMMA material, but it is not limited to transparency. The present invention uses transparency as an example to illustrate that the performance of the PMMA material obtained is improved.

[0097] Table 2

[0098]

[0099] Table 3

[0100]

[0101] In summary, the method for reducing dissolved oxygen in MMA raw material liquid provided by the present invention first performs gas replacement treatment on the MMA raw material liquid. During this process, nitrogen is fully mixed into the MMA raw material liquid, which is helpful for removing dissolved oxygen. The treated MMA raw material liquid is subjected to decompression degassing treatment. During the decompression process, the solubility of the gas is reduced, and the dissolved oxygen escapes from the MMA raw material liquid together with the nitrogen, and the dissolved oxygen remaining in the MMA raw material liquid is further removed, thereby obtaining a MMA raw material liquid with low dissolved oxygen. When a subsequent polymerization reaction is carried out, oxygen-induced MMA polymerization reaction products can be reduced, and the obtained PMMA material has the characteristics of strong thermal stability, good weather resistance, high transparency, etc., and can be expanded for application in occasions with higher standards.

[0102] The method for reducing dissolved oxygen in MMA raw material liquid provided by the present invention can separate the MMA raw material liquid and nitrogen in the gas for recycling, thereby reducing the loss of materials and being beneficial to energy saving and efficiency improvement.

[0103] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for reducing dissolved oxygen in MMA raw material solution, characterized in that: The method comprises the following steps: (1) Mixing the MMA raw material liquid with nitrogen and performing gas replacement treatment to obtain a mixed MMA raw material liquid; (2) subjecting the mixed MMA raw material liquid obtained in step (1) to a decompression degassing treatment to obtain a mixed gas and an MMA raw material liquid with low dissolved oxygen; (3) The mixed gas obtained in step (2) is pressurized, condensed and separated in sequence to separate nitrogen, oxygen and MMA raw material liquid.

2. The method according to claim 1, characterized in that The temperature of the gas replacement treatment in step (1) is between -10°C and 45°C, and the pressure is greater than 2.5 MPaG.

3. The method according to claim 1, characterized in that The pressure of the reduced pressure degassing treatment in step (2) is 0.102-0.105 MPaG.

4. The method according to claim 1, characterized in that: The pressure of the supercharged mixed gas in step (3) is greater than 2.6 MPaG.

5. The method according to claim 1, characterized in that The condensation temperature in step (3) is between -10°C and 40°C; The MMA raw material liquid produced after the condensation in step (3) is recycled and used in the gas replacement process.

6. The method according to claim 1, characterized in that The separation in step (3) includes membrane separation, and the membrane used for membrane separation is a membrane with an oxygen permeation rate greater than the nitrogen and MMA permeation rates; The material of the membrane used for membrane separation includes polyimide or polysulfone; After the membrane separation, oxygen-rich gas and nitrogen-rich gas are obtained, and the nitrogen-rich gas is recycled and used in the gas replacement process.

7. The method according to claim 1, characterized in that The method is carried out in a device system for reducing dissolved oxygen in an MMA raw material liquid, wherein the device system comprises a booster pump, a mixing device, a pressure reducing valve and a degassing device connected in sequence along a material flow direction, wherein a compressor, a condenser and a membrane separation device are connected in sequence to the top of the degassing device, and an MMA raw material liquid with low dissolved oxygen is discharged from the bottom of the degassing device; a nitrogen inlet pipeline is connected between the booster pump and the mixing device; The MMA raw material liquid discharged from the condenser is recycled and used in the mixing device; The nitrogen-rich gas discharged from the membrane separation device is recycled back to the mixing device.

8. The method according to claim 1, characterized in that The method comprises the following steps: (1) The MMA raw material liquid is pumped into a mixing device with a pressure greater than 2.5 MPaG through a booster pump, and nitrogen is introduced through a nitrogen inlet pipeline, and mixed at -10°C to 45°C for gas replacement treatment to obtain a mixed MMA raw material liquid; (2) The mixed MMA raw material liquid obtained in step (1) is decompressed to 0.102-0.105 MPaG through a pressure reducing valve and then sent to a degassing device for decompression and degassing to obtain a mixed gas and a MMA raw material liquid with low dissolved oxygen; (3) The mixed gas obtained in step (2) is pressurized to a level greater than 2.6 MPaG by a compressor and condensed by a condenser at a temperature of -10°C to 40°C. The generated MMA raw liquid is recycled back to the mixing device for gas replacement treatment. The mixed gas is then separated by a membrane separation device to obtain oxygen-rich gas and nitrogen-rich gas. The obtained nitrogen-rich gas is recycled back to the mixing device for gas replacement treatment, thereby achieving separation of nitrogen, oxygen and MMA raw liquid.

9. A low dissolved oxygen MMA raw material solution, characterized in that: The MMA raw material solution is obtained by processing the method according to any one of claims 1 to 8.

10. An application of the low dissolved oxygen MMA raw material solution as claimed in claim 9, characterized in that: The PMMA material obtained by polymerizing the MMA raw material liquid is used in electronic equipment, aerospace and medical fields.

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