A process for the recovery of high-boiling monomers in a bio-based rubber emulsion

Abstract

The application provides a recovery process of high-boiling-point monomers in a bio-based rubber emulsion, comprising the following steps: S1) mixing the bio-based rubber emulsion and a terminator, and then performing flash evaporation to obtain pretreated bio-based rubber emulsion; S2) mixing the pretreated bio-based rubber emulsion and an agglomerating agent solution, and then introducing steam; S3) using an extractant to extract the obtained emulsion; S4) performing centrifugal separation on the extracted emulsion; S5) performing flash evaporation on the separated solvent to obtain residual monomers; and S5) separating and purifying the residual monomers and free monomers to obtain recovered monomers. In the application, the agglomerating agent is added to the emulsion system to increase the particle size of the colloidal particles, thereby reducing the steric hindrance of monomers from the emulsified state to the free state; the steam partial pressure is used to separate the monomers remaining in the colloidal particles and micelles; then a suitable extractant is selected to extract the free monomers into an extractant solution; and finally, the residual monomers are separated out through centrifugation, so that the monomers are recovered.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of bio-based rubber preparation, and particularly relates to a recovery process of high-boiling-point monomers in bio-based rubber emulsion. BACKGROUND

[0002] Emulsion polymerization is a process in which monomers are dispersed in water to form an emulsion by means of emulsifiers and mechanical stirring, and then an initiator is added to initiate polymerization of the monomers. Emulsion polymerization is a method for preparing emulsion materials and solid polymers, but due to the polymerization process, the monomer conversion rate is generally difficult to reach 100%, especially in the preparation of rubber technology by emulsion polymerization, in order to control the molecular structure and application performance of the product, the monomer conversion rate is often controlled at 70-80%. The conversion rate of the existing butadiene styrene rubber and nitrile rubber polymerization process is controlled at about 70% to obtain a rubber product with low branching structure. The recovery process of these two kinds of rubber monomers is relatively mature. First, the unreacted butadiene monomer is removed by flash evaporation, and then the unreacted styrene or acrylonitrile is removed by stripping. Through a certain recovery process, monomer recovery and reuse can be achieved.

[0003] The current new generation of bio-based rubber is also prepared by emulsion polymerization technology. The monomers are butadiene, itaconate or fumarate, and the third monomer. It is prepared by emulsion polymerization of bio-based ester monomers-itaconate and fumarate, diene monomers, modified monomers, emulsifiers, initiation systems, molecular weight regulators, water and other components. Among them, itaconate and fumarate belong to high-boiling-point monomers. The boiling point of dimethyl itaconate is 208℃, and the boiling point of dibutyl itaconate is 307℃. There is no paper or patent to introduce and study the recovery of high-boiling-point monomers in emulsion polymerization.

[0004] As described above, the current emulsion polymerization of small molecule monomers such as butadiene, isoprene, and acrylonitrile can achieve the effect of recovery through conventional flash evaporation or stripping process; for some medium-boiling-point monomers such as styrene and methyl methacrylate, the monomers remaining in the system can be recovered by stripping process; in the pursuit of new materials with high performance and new applications, some special monomers are introduced into the emulsion polymerization system, which can solve the problem to a certain extent. However, due to the high boiling point of some monomers (boiling point above 200℃), it is difficult to recover the monomers. Flash evaporation cannot reach the boiling point of the monomers, and it is difficult to remove the monomers. The stripping method cannot meet the conditions for removing the monomers, which seriously affects the production cost and product quality. At present, the recovery of itaconate and fumarate in the production of existing bio-based rubber (itaconate or fumarate-based rubber) has the above problems.

[0005] Polymer monomers are the basic raw materials for synthetic polymers, but some polymer monomers are left in the polymer material during production, which has unpredictable effects on product performance and can overflow or release during processing. These residual polymer monomers are toxic and harmful, and can have adverse effects on the environment and the human body.

[0006] In addition to conventional flashing and stripping, residual monomers can also be treated by secondary polymerization to reduce the amount of monomer residues and achieve the effect of monomer removal. Chinese Patent No. 201010231458.X provides a method for chemically removing residual monomers in rubber latex, which adds a water-soluble initiator under a nitrogen pressure of 0.02 MPa to 0.04 MPa when the monomer conversion rate reaches 85% or more during the process of obtaining rubber latex by emulsion polymerization, and the reaction time is 1 to 3 hours. The prepared rubber has less impurities, short degassing time, and high production efficiency for synthetic rubber latex, but the crosslinking and grafting of the molecular structure caused by secondary polymerization can seriously affect product performance, so this method is not suitable for preparing rubber product systems.

[0007] A similar research to the present process technology is provided in Chinese Patent No. 201310432984.6, which provides a production process for low-VOC polyurethane home decoration coatings. The extraction process is introduced into the polyurethane production process, and a mixture of 120# gasoline and benzene is selected as the extraction liquid to continuously extract the free state toluene diisocyanate in the polymer component. Then the extraction mixture is extracted or pressed into a distillation container with compressed air, and the extraction liquid is distilled out. The residual mixture after distillation is a mixture of unreacted toluene diisocyanate and a small amount of extraction liquid, and the toluene diisocyanate is recovered. This process is easy to implement in a low-resistance system, but for an emulsion polymerization system, the recovery rate of the monomer will be low by relying on the extraction process alone, because the monomer is mostly in an emulsified form in the system, making it difficult to enter the extraction liquid for separation.

[0008] In summary, in an emulsion polymerization system, it is difficult to recover high-boiling-point monomers, and the conventional stripping process requires a large amount of steam and has a low recovery rate. In an emulsion polymerization system, the extraction process has a large steric hindrance from the emulsifier, and the recovery rate is low. Therefore, it is of great significance to provide a process for recovering high-boiling-point monomers in bio-based rubber emulsion polymerization. SUMMARY

[0009] The technical problem solved by the present application is to provide a process for recovering high-boiling-point monomers in bio-based rubber emulsion. The recovery process provided in the present application can achieve the recovery of high-boiling-point monomers with a high recovery rate.

[0010] Therefore, the application provides a recovery process of high-boiling-point monomers in a bio-based rubber emulsion, comprising the following steps:

[0011] S1) mixing the bio-based rubber emulsion and a termination agent and then performing flash evaporation to obtain a pretreated bio-based rubber emulsion; the latex solid content in the bio-based rubber emulsion is 1-75 wt%, and the residual amount of high-boiling-point monomers is 0.01-100 wt%;

[0012] S2) mixing the pretreated bio-based rubber emulsion and an agglomeration agent solution and then introducing steam;

[0013] S3) performing extraction on the emulsion obtained in step S2) by using an extraction agent to obtain free monomers and an extracted emulsion;

[0014] S4) performing centrifugal separation on the extracted emulsion to obtain a solvent containing residual monomers and a latex;

[0015] S5) performing flash steam extraction on the solvent containing residual monomers to obtain residual monomers;

[0016] S5) separating and purifying the residual monomers and the free monomers to obtain recovered monomers.

[0017] Preferably, the bio-based rubber emulsion is 100 parts by weight, the termination agent is 0.1-5 parts by weight, the agglomeration agent is 0.01-5 parts by weight, and the extraction agent is 20-1000 parts by weight.

[0018] Preferably, the termination agent is selected from one or more of sodium polysulfide, nitrite, hydroxylamine compounds, and sodium dimethyl dithiocarbamate;

[0019] The agglomeration agent is selected from one or more of acetic acid, propionic acid, butyric acid, oxalic acid, ammonium sulfate, ammonium carbonate, ammonium bicarbonate, ammonium chloride, ammonium acetate, ammonium oxalate, sodium acetate, sodium oxalate, sodium acetate, potassium chloride, sodium chloride, amino-oleic acid ester, carbamate, methyl carbamate, amino propylamine dioleate, glycerol oleate, and polyether amine with a molecular weight <400;

[0020] The extraction agent is selected from one or more of benzene, toluene, monochloromethane, dichloromethane, carbon disulfide, hexane, heptane, isooctane, dimethylbenzene, cyclohexane, petroleum ether, pentane, diethyl ether, and ethyl acetate.

[0021] Preferably, in step S1), the temperature of the flash evaporation is 30-45℃, and the flash evaporation is performed under a vacuum of -0.065 to -0.095 MPa.

[0022] Preferably, in step S2), the agglomerating agent solution is a 0.1-5wt% agglomerating agent aqueous solution, the mixing temperature is 30-45℃, and the stirring time is 0.5-4h; the steam is water steam or solvent steam, the pressure is 0.05-0.45MKPa, and the time of steam input is 0.2-1.5h.

[0023] Preferably, the average latex particle size of the pre-processed bio-based rubber emulsion is 50-150nm, and the average latex particle size after mixing with the agglomerating agent solution is 200-250nm.

[0024] Preferably, in step S3), the extraction is specifically:

[0025] In the emulsion obtained in step S2), an extraction agent is added, and stirring is performed at a speed of 100-230rpm for 20-90min, and the temperature is lowered to 10-25℃, and stirring is performed at a speed of 20-100rpm.

[0026] Preferably, in step S4), the feeding speed of the centrifugal separation is 10-25L / min, and the rotation speed is 4000-8000rpm.

[0027] Preferably, in step S5), the steam pressure of the flash steam extraction is 0.25-0.45MPa, and the vacuum degree is -0.075--0.095MPa.

[0028] Preferably, the bio-based rubber emulsion is selected from the group consisting of di-n-butyl itaconate-butadiene polymer emulsion, dimethyl fumarate-butadiene polymer emulsion, dimethyl itaconate-butadiene-glycidyl methacrylate polymer emulsion, dibutyl fumarate-butadiene polymer emulsion, diethyl itaconate-butadiene-methacrylic acid polymer emulsion, or dimethyl itaconate-isoprene polymer emulsion, the latex solid content is 20-50wt%, and the high-boiling-point monomer residual amount is 2-25wt%; the boiling point of the high-boiling-point monomer is >200℃.

[0029] The application provides a recovery process of high-boiling-point monomers in a bio-based rubber emulsion, which first mixes the bio-based rubber emulsion and a terminator, then performs flash evaporation to obtain a pretreated bio-based rubber emulsion, so as to remove unreacted low-boiling-point dienes in the bio-based rubber emulsion, then mixes the pretreated bio-based rubber emulsion and an agglomerating agent solution, and introduces steam, so as to increase the particle size of the rubber particles in the emulsion through the agglomeration of the agglomerating agent, reduce the steric hindrance of the high-boiling-point monomers from the emulsified state to the free state, then free the monomers remaining in the rubber particles and micelles through the steam partial pressure, then extracts the free monomers through extraction, then separates the monomer solution from the extracted emulsion through centrifugation, then flash evaporates the solution containing the residual monomers to obtain residual monomers, and finally separates and purifies the monomers to obtain recovered monomers. Thus, the recovery process provided by the application realizes the effective recovery of high-boiling-point monomers through the above pretreatment, agglomeration, extraction, centrifugal separation, solvent recovery and monomer recovery, and the recovery rate is ≥85%. DETAILED DESCRIPTION

[0030] In order to further understand the present application, the preferred embodiments of the present application are described below in conjunction with examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present application, and are not limitations on the claims of the present application.

[0031] In view of the problems of great difficulty in recovering high-boiling-point monomers in a bio-based rubber emulsion and low recovery rate in the prior art, the application provides a recovery process of high-boiling-point monomers in a bio-based rubber emulsion, which adds an agglomerating agent to a bio-based rubber emulsion system to increase the particle size of the rubber particles, omits the amount of surfactant on the surface of the rubber particles, reduces the steric hindrance of the high-boiling-point monomers from the emulsified state to the free state, then frees the monomers remaining in the rubber particles and micelles through the steam partial pressure, then extracts the free monomers into an extraction liquid by using a suitable extractant, and separates the residual monomers through centrifugation to realize monomer recovery. Specifically, the application discloses a recovery process of high-boiling-point monomers in a bio-based rubber emulsion, which comprises the following steps:

[0032] S1) mixing a bio-based rubber emulsion and a terminator, then performing flash evaporation to obtain a pretreated bio-based rubber emulsion; the latex solid content in the bio-based rubber emulsion is 1-75 wt%, and the residual amount of high-boiling-point monomers is 0.01-100 wt%;

[0033] S2) mixing the pretreated bio-based rubber emulsion and an agglomerating agent solution, then introducing steam;

[0034] S3) extracting the emulsion obtained in step S2) by using an extractant to obtain free monomers and an extracted emulsion;

[0035] S4) centrifugally separating the extracted emulsion to obtain a solvent containing residual monomers and a latex;

[0036] S5) flash stripping the solvent containing the residual monomer to obtain the residual monomer;

[0037] S5) separating and purifying the residual monomers and free monomers to obtain recovered monomers.

[0038] The recycling process provided in the present application is aimed at the recovery of high-boiling-point monomers in the emulsion produced in the process of preparing bio-based rubber, wherein the bio-based rubber is a rubber prepared by emulsion polymerization of bio-based ester monomers, diene monomers, modified monomers, emulsifiers, initiation systems, molecular weight regulators, water and other components, wherein the bio-based ester monomers include itaconates and fumarates; itaconates include dimethyl itaconate, monomethyl itaconate, diethyl itaconate, monoethyl itaconate, dipropyl itaconate, monopropyl itaconate, dibutyl itaconate, monobutyl itaconate, dipentyl itaconate, monopentyl itaconate, dihexyl itaconate, monohexyl itaconate, diheptyl itaconate, monoheptyl itaconate, One or more of dioctyl itaconate, monooctyl itaconate, dinonyl itaconate, monononyl itaconate, didecyl itaconate and monodecyl itaconate; fumarate esters include one or more of dimethyl fumarate, monomethyl fumarate, diethyl fumarate, monoethyl fumarate, dipropyl fumarate, monopropyl fumarate, dibutyl fumarate, monobutyl fumarate, dipentyl fumarate, monopentyl fumarate, dihexyl fumarate, monohexyl fumarate, diheptyl fumarate, monoheptyl fumarate, dioctyl fumarate, monooctyl fumarate, dinonyl fumarate, monononyl fumarate, didecyl fumarate and monodecyl fumarate. The above itaconates and fumarates all belong to the category of high boiling point monomers.

[0039] The diene monomers are specifically butadiene and isoprene; the modified monomers include one or more of styrene, p-methylstyrene, acrylonitrile, acrylic acid, methacrylic acid, ethyl acrylate, butyl acrylate, methyl methacrylate, glycidyl methacrylate, hydroxyethyl methacrylate, butyl methacrylate, dimethylaminoethyl methacrylate, ethyl acetoacetate methacrylate, diallyl phthalate, glycidyl versatate, epoxy resin, vinyltrimethoxysilane and vinyltriisopropoxysilane; the emulsifier, initiator system, molecular weight regulator and water are all conventional emulsion polymerization components.

[0040] In specific embodiments, the bio-based rubber emulsion is selected from the group consisting of di-n-butyl itaconate-butadiene polymer emulsion, dimethyl fumarate-butadiene polymer emulsion, dimethyl itaconate-butadiene-glycidyl methacrylate polymer emulsion, dibutyl fumarate-butadiene polymer emulsion, diethyl itaconate-butadiene-methacrylic acid polymer emulsion, and dimethyl itaconate-isoprene polymer emulsion; wherein the latex solid content is 1-75 wt%, the high-boiling monomer residual amount is 0.01-100 wt%, specifically, the latex solid content is 20-50 wt%, and the high-boiling monomer residual amount is 2-25 wt%; and the high-boiling monomer has a boiling point > 200°C.

[0041] The bio-based rubber emulsion is first pretreated to remove unreacted low-boiling diene monomers, such as butadiene and isoprene, specifically:

[0042] The bio-based rubber emulsion and the terminating agent are mixed, and the temperature is raised to 30-45°C, and vacuum is applied to -0.065 to -0.095 MPa for flash evaporation.

[0043] The terminating agent is added in the above pretreatment to avoid further reaction of residual monomers in the emulsion, eliminate free radical activity, and avoid self-polymerization and graft polymerization. The terminating agent is selected from one or more of sodium polysulfide, nitrite, hydroxylamine compounds, and sodium dimethyl dithiocarbamate, specifically, the terminating agent is selected from one or two of isopropyl hydroxylamine, sodium polysulfide, sodium dimethyl dithiocarbamate, dimethyl hydroxylamine, and sodium nitrite. In the above pretreatment process, the flash evaporation temperature is 35-40°C, and the vacuum degree is -0.085 to -0.090 MPa.

[0044] According to the present invention, the pretreated bio-based rubber latex and agglomerant solution are then mixed and agglomerated, and steam is then introduced. The average particle size of the bio-based rubber latex is 50-150 nm, and the agglomeration process increases the latex particle size to 200-350 nm to facilitate the release of high-boiling-point monomers from the micelles. The agglomerant is selected from a weak acid, a weak acid salt, or an inorganic salt, which primarily acts on the emulsifier system, reducing the stability of the emulsification system and providing the possibility for two micelles to coalesce. Compounds containing ester groups or amino groups act through bridging, pulling the micelles together to achieve the agglomeration effect. To ensure the release of monomers, the latex is further treated by introducing water vapor, solvent vapor, etc. to provide the latex with sufficient temperature or free space, while also accelerating the monomer release rate. Specifically, the agglomerating agent is selected from one or more of acetic acid, propionic acid, butyric acid, oxalic acid, ammonium sulfate, ammonium carbonate, ammonium bicarbonate, ammonium chloride, ammonium acetate, ammonium oxalate, ammonium acetate, sodium acetate, sodium oxalate, sodium acetate, potassium chloride, sodium chloride, oleoamino oleate, carbamate, methyl carbamate, aminopropylamine dioleate, oleic acid glyceride, and polyetheramine with a molecular weight of less than 400; illustratively, the agglomerating agent is selected from one or more of acetic acid, ammonium acetate, oleoamino oleate, potassium chloride, polyetheramine, sodium chloride, ammonium oxalate, methyl carbamate, ammonium sulfate, oxalic acid, oleic acid glyceride, ammonium acetate, and aminopropylamine dioleate. The agglomerating agent solution is a 0.1-5 wt% agglomerating agent aqueous solution, specifically, the agglomerating agent solution is a 0.5-3 wt% agglomerating agent aqueous solution, more specifically, the agglomerating agent solution is a 0.8-1 wt% agglomerating agent aqueous solution. The steam is water steam or solvent steam, and specifically, the solvent steam is hexane steam, carbon disulfide steam or dichloromethane steam. The above process is specifically as follows:

[0045] The bio-based rubber latex and the agglomerating agent are mixed, stirred at 30-45° C. for 0.5-4 hours for agglomeration, and then steam is introduced with a steam pressure of 0.05-0.45 MPa for 0.2-1.5 hours.

[0046] In the above process, the agglomeration temperature is 35-40°C, the stirring time is 1-3 hours, more specifically, the stirring time is 1.5-2 hours; the steam pressure is 0.15-0.4 MPa, and the introduction time is 0.4-1.2 hours; specifically, the steam pressure is 0.25-0.38 MPa, and the introduction time is 0.5-1 hour; more specifically, the steam pressure is 0.30-0.35 MPa, and the introduction time is 0.6-0.8 hours.

[0047] Through the above-mentioned agglomeration, steam shock and temperature increase, the residual monomers are accelerated to be freed from the colloid particles into monomer droplets.

[0048] The emulsion obtained is then extracted with an extractant to obtain free monomers and an extracted emulsion; wherein the extractant is selected from organic solvents that are mutually insoluble with water, and are prone to stratification under centrifugation or static state, so as to achieve the purpose of extraction; meanwhile, the extractant has a low boiling point and is easy to separate from the extracted monomers, so as to achieve the purpose of monomer refining and recovery. The extractant is one or more of benzene, toluene, monochloromethane, dichloromethane, carbon disulfide, hexane, heptane, isooctane, dimethylbenzene, cyclohexane, petroleum ether, pentane, diethyl ether and ethyl acetate; specifically, the extractant is selected from heptane, pentane, cyclohexane, carbon disulfide, ethyl acetate, benzene, isooctane, petroleum ether, dichloromethane or heptane. The above extraction process is specifically as follows:

[0049] The extractant is added to the emulsion, the stirring speed is 100-230 rpm, the extraction is performed for 20-90 min, the temperature is reduced to 10-25 °C (to reduce the emulsifying capacity of the emulsifier and reduce the residual amount of the solvent), the stirring speed is reduced to 20-100 rpm, and the free monomers are extracted.

[0050] In the above process, the stirring speed is specifically 130-200 rpm, and the extraction time is 30-80 min; more specifically, the stirring speed is 150-180 rpm, and the extraction time is 45-60 min; the temperature is reduced to 15-20 °C, and the stirring speed is 30-80 rpm; more specifically, the temperature is reduced to 16-18 °C, and the stirring speed is 40-60 rpm.

[0051] According to the present application, the extracted emulsion is then subjected to centrifugal separation, and the solvent with residual monomers is separated from the latex under the action of centrifugation; the feeding speed of the centrifugal separation is 10-25 L / min, and the rotation speed is 4000-8000 rpm; specifically, the feeding speed of the centrifugal separation is 12-20 L / min, and the rotation speed is 5000-7000 rpm; more specifically, the feeding speed of the centrifugal separation is 15-18 L / min, and the rotation speed is 6000-6800 rpm.

[0052] After centrifugal separation, the solvent containing residual monomers obtained is subjected to flash steam stripping to remove residual solvent; in the process of flash steam stripping, water vapor is introduced, the steam pressure is 0.25-0.45 MPa, and the vacuum degree is -0.075 to -0.095 MPa after vacuumizing; specifically, the steam pressure is 0.30-0.35 MPa, and the vacuum degree is -0.080 to -0.085 MPa after vacuumizing.

[0053] Finally, the above residual monomers and free monomers are purified to obtain recovered monomers; the purification is performed according to methods well known to those skilled in the art, and the present application does not have special limitations.

[0054] In the process of recycling high-boiling monomers in the present application, the bio-based rubber emulsion is 100 parts by weight, the terminator is 0.1-5 parts by weight, the agglomeration agent is 0.01-5 parts by weight, and the extractant is 20-1000 parts by weight; specifically, the content of the terminator is 0.25-4 parts by weight, specifically, the content of the terminator is 0.35-3 parts by weight, specifically, the content of the terminator is 0.4-2 parts by weight, specifically, the content of the terminator is 0.45-1.05 parts by weight, specifically, the content of the terminator is 0.6-1.0 parts by weight; specifically, the content of the agglomeration agent is 0.035-4 parts by weight, more specifically, the content of the agglomeration agent is 0.065-3 parts by weight; for example, the content of the agglomeration agent in the present application is 0.025 parts by weight, 0.01 parts by weight, 0.125 parts by weight, 0.12 parts by weight, 0.14 parts by weight, 0.15 parts by weight, 0.155 parts by weight, 0.16 parts by weight, 0.20 parts by weight, 0.25 parts by weight, 0.45 parts by weight, 0.60 parts by weight, 0.70 parts by weight, 0.85 parts by weight, 0.92 parts by weight, 1 parts by weight, 1.6 parts by weight, 1.9 parts by weight, 2.1 parts by weight, 2.3 parts by weight, 2.6 parts by weight, 2.8 parts by weight or 2.9 parts by weight. The content of the extractant is specifically 30-800 parts by weight, specifically 50-650 parts by weight, specifically 60-600 parts by weight, specifically 75-530 parts by weight, specifically 80-500 parts by weight, specifically 90-410 parts by weight, specifically 100-400 parts by weight, specifically 110-390 parts by weight, specifically 105-360 parts by weight, specifically 110-300 parts by weight, specifically 130-270 parts by weight, specifically 150-250 parts by weight, and specifically 180-220 parts by weight.

[0055] The present application provides a recycling process for high-boiling monomers in a bio-based rubber emulsion. The reason why the high-boiling monomers are difficult to extract is that the particle size is small and the micelles are wrapped around the monomers. The present application adds an agglomeration agent to perform an agglomeration process, which increases the size of the colloidal particles, reduces the attachment of emulsifiers on the surface of the colloidal particles, and allows the high-boiling monomers to be free. Steam contacts the monomers to increase the temperature of the system and accelerate the release of monomers. At the same time, the steam can drive the monomers to move from the micelles to the outside of the micelles, and then the monomers are released from the micelles. Subsequent extraction is performed using a low-boiling solvent to extract the monomers at high temperature. Finally, the solvent and the emulsion are separated by centrifugation, and the recycled monomers with high recovery rate are obtained after purification.

[0056] In order to further understand the present application, the recycling process for high-boiling monomers in a bio-based rubber emulsion provided by the present application is described in detail below with reference to the examples, and the protection scope of the present application is not limited by the following examples.

[0057] Example 1

[0058] 1. Pretreatment

[0059] After emulsion polymerization of di-n-butyl itaconate-diene polymer emulsion, wherein the gel content is 25% and the residual di-n-butyl itaconate is 2.8%, 200 kg of di-n-butyl itaconate-diene polymer emulsion is added into a reaction kettle, 0.8 kg of isopropyl hydroxylamine is added, the temperature is raised to 35°C, vacuum is extracted at -0.085 MPa, and flash evaporation is performed to remove unreacted low-boiling diene, butadiene or isoprene;

[0060] 2. Agglomeration

[0061] Agglomerating agent solution preparation: 0.03 kg of acetic acid and 0.1 kg of ammonium acetate are prepared into a 1% aqueous solution:

[0062] The above agglomerating agent solution is added into the pretreated polymer emulsion, the temperature is maintained at 35°C, and stirring is performed for 1 h to perform size expansion, hexane steam is introduced, the steam pressure is 0.3 MPa, and continuous introduction is performed for 0.5 h; through steam impact, temperature increase, and similar compatibility principles, the residual monomer is accelerated to separate from the colloidal particles to monomer droplets;

[0063] 3. Extraction

[0064] Hexane 200 kg is added into the agglomerated emulsion, the stirring speed is controlled at 100 rpm, under strong stirring, extraction is performed for 30 min, the temperature is reduced to 15°C (to reduce the emulsifying capacity of the emulsifier and reduce the residual amount of the solvent), the stirring speed is reduced to 40 rpm, and the extracted monomer is extracted;

[0065] 4. Centrifugal separation

[0066] The extracted emulsion is introduced into a disc centrifuge at a speed of 15 L / min, the centrifuge rotates at 6000 rpm, and under the action of centrifugation, the solvent with residual monomers is separated from the latex;

[0067] 5. Solvent recovery

[0068] The solvent with residual monomers is flash evaporated, water vapor is introduced, the solvent is removed under the conditions of steam pressure 0.35 MPa and vacuum degree -0.085 MPa, and the residual monomer is obtained;

[0069] 6. Monomer recovery

[0070] All the monomers obtained above are separated and purified through a rectifying column to obtain recovered monomers.

[0071] Example 2

[0072] 1. Pretreatment

[0073] After emulsion polymerization of itaconic acid di-n-butyl ester-butadiene polymer emulsion, wherein the gel content is 25% and the residual itaconic acid di-n-butyl ester is 2.8%, 200 kg of itaconic acid di-n-butyl ester-butadiene polymer emulsion is added into a reaction kettle, 0.8 kg of isopropyl hydroxylamine is added, the temperature is raised to 35°C, vacuum is extracted at -0.085 MPa, and unreacted low-boiling diene, butadiene or isoprene is removed by flash evaporation;

[0074] 2. Agglomeration

[0075] The agglomeration agent solution is prepared by dissolving 0.04 kg of oil amino oleate and 0.2 kg of potassium chloride in 0.5% aqueous solution;

[0076] The above agglomeration agent solution is added to the polymer emulsion, the temperature is maintained at 30°C, and stirring is performed for 1.5 h to expand the diameter. Water vapor is introduced at a steam pressure of 0.35 MPa for a continuous introduction time of 0.2 h. Through steam shock, temperature rise and similar compatibility principles, the residual monomer is accelerated to separate from the colloidal particles to monomer droplets;

[0077] 3. Extraction

[0078] Pentane 200 kg is added to the agglomerated emulsion, and the stirring speed is controlled at 100 rpm. Under strong stirring, the extraction is performed for 30 min, and the temperature is lowered to 15°C (to reduce the emulsifying capacity of the emulsifier and reduce the residual amount of solvent). The stirring speed is reduced to 30 rpm, and the extracted monomers are extracted;

[0079] 4. Centrifugal separation

[0080] The extracted emulsion is introduced into a disc centrifuge at a speed of 15 L / min, and the centrifuge rotates at a speed of 5000 rpm. Under the action of centrifugation, the solvent with residual monomers is separated from the latex;

[0081] 5. Solvent recovery

[0082] The solvent with residual monomers is flash evaporated by introducing water vapor at a steam pressure of 0.35 MPa, and the solvent is removed under the condition of vacuum extraction at a vacuum degree of -0.085 MPa to obtain residual monomers;

[0083] 6. Monomer recovery

[0084] All the monomers obtained above are separated and purified by a rectifying column to obtain recovered monomers.

[0085] Example 3

[0086] 1. Pretreatment

[0087] 200 kg of di-n-butyl itaconate-butadiene polymer emulsion after emulsion polymerization, wherein the rubber content is 25% and the residual amount of di-n-butyl itaconate is 2.8%, is added to a reaction kettle, 0.8 kg of isopropylhydroxylamine is added, the temperature is raised to 35° C., and a vacuum of -0.085 MPa is applied for flash evaporation to remove unreacted low-boiling dienes, butadiene or isoprene;

[0088] 2. Agglomeration

[0089] Preparation of agglomerating agent solution: 0.02 kg of 200 polyetheramine and 0.3 kg of sodium chloride were prepared into a 0.5% aqueous solution;

[0090] The agglomerant solution was added to the pretreated polymer emulsion, the temperature was maintained at 35°C, and the mixture was stirred for 1 hour to expand the diameter. Water vapor was introduced at a steam pressure of 0.35 MPa for 0.4 hours. The steam shock, temperature increase, and the principle of like dissolves like were used to accelerate the release of residual monomers from the colloid particles to the monomer droplets.

[0091] 3. Extraction

[0092] Add 150 kg of cyclohexane to the agglomerated emulsion, control the stirring speed to 150 rpm, extract for 45 minutes under strong stirring, cool to 10°C (to reduce the emulsification ability of the emulsifier and the amount of residual solvent), reduce the stirring speed by 20 rpm, and extract the free monomer;

[0093] 4. Centrifugal separation

[0094] The extracted emulsion is fed into a disc centrifuge at a speed of 10 L / min and a centrifuge speed of 7000 rpm to separate the solvent containing residual monomers from the latex under centrifugal action;

[0095] 5. Solvent recovery

[0096] The solvent containing the residual monomers was flash stripped, and water vapor was introduced at a steam pressure of 0.35 MPa and a vacuum degree of -0.09 MPa to remove the residual solvent to obtain the residual monomers;

[0097] 6. Monomer recovery

[0098] All the monomers obtained above are separated and purified by a distillation tower to obtain recovered monomers.

[0099] Example 4

[0100] 1. Preprocessing

[0101] After emulsion polymerization of itaconic acid di-n-butyl ester-butadiene polymer emulsion, wherein the gel content is 25% and the residual itaconic acid di-n-butyl ester is 2.8%, 200 kg of itaconic acid di-n-butyl ester-butadiene polymer emulsion is added into a reaction kettle, 0.8 kg of isopropyl hydroxylamine is added, the temperature is raised to 35°C, vacuum is extracted at -0.085 MPa, and unreacted low-boiling diene, butadiene or isoprene is removed by flash evaporation;

[0102] 2, agglomeration

[0103] Agglomerating agent solution preparation: ammonium oxalate 0.2 kg, sodium chloride 0.3 kg, methyl carbamate 0.02 kg are prepared into a 0.5% aqueous solution;

[0104] The above agglomerating agent solution is added to the pretreated polymer emulsion, the temperature is maintained at 35°C, and stirring is carried out for 1 h to expand the diameter, carbon disulfide vapor is introduced, the vapor pressure is 0.15 MPa, and the continuous introduction time is 0.4 h; by steam shock, temperature rise, and similar compatibility principle, the residual monomer is accelerated to separate from the colloidal particles to monomer droplets;

[0105] 3, extraction

[0106] In the agglomerated emulsion, 100 kg of carbon disulfide is added, the stirring speed is controlled at 200 rpm, under strong stirring, extraction is carried out for 60 min, the temperature is lowered to 10°C (to reduce the emulsifying ability of the emulsifier and reduce the residual amount of solvent), and the stirring speed is lowered to 20 rpm to extract the monomers;

[0107] 4, centrifugal separation

[0108] The extracted emulsion is introduced into a disc centrifuge at a speed of 10 L / min, and the centrifuge rotates at 7000 rpm, under the action of centrifugation, the solvent with residual monomers is separated from the latex;

[0109] 5, solvent recovery

[0110] The solvent with residual monomers is flash evaporated, water vapor is introduced, the residual solvent is removed under the conditions of steam pressure 0.35 MPa and vacuum degree -0.095 MPa, and the residual monomers are obtained;

[0111] 6, monomer recovery

[0112] All the monomers obtained above are separated and purified by a rectifying column to obtain recovered monomers.

[0113] Example 5

[0114] 1, pretreatment

[0115] After emulsion polymerization of itaconic acid diethyl ester-isoprene polymer emulsion, wherein the gel content is 35% and the residual itaconic acid diethyl ester monomer is 3.6%, 200 kg of itaconic acid diethyl ester-isoprene polymer emulsion is added into a reaction kettle, 0.3 kg of sodium polysulfide and 0.6 kg of sodium dimethyl dithiocarbamate are added, the temperature is raised to 40°C, vacuum is extracted at -0.09 MPa, and unreacted low-boiling diene, butadiene or isoprene, is removed by flash evaporation;

[0116] 2. Agglomeration

[0117] Agglomeration agent solution preparation: 0.3 kg of ammonium sulfate, 0.1 kg of ammonium oxalate, and 0.1 kg of potassium chloride are prepared into a 0.8% aqueous solution;

[0118] The agglomeration agent is added to the polymer emulsion, the temperature is maintained at 35°C, and stirring is performed for 1 h to expand the diameter. Water vapor is introduced at a steam pressure of 0.35 MPa for 1 h of continuous introduction time. The residual monomer is accelerated to separate from the latex particles to monomer droplets by steam shock, temperature rise, and similar compatibility principles;

[0119] 3. Extraction

[0120] Hexane 200 kg is added to the agglomerated emulsion, and the stirring speed is controlled at 130 rpm. Under strong stirring, the extraction is performed for 45 min, and the temperature is lowered to 15°C (to reduce the emulsifying capacity of the emulsifier and reduce the residual amount of solvent). The stirring speed is reduced to 30 rpm to extract the monomers;

[0121] 4. Centrifugal separation

[0122] The extracted emulsion is introduced into a disc centrifuge at a speed of 15 L / min, and the centrifuge rotates at 6000 rpm. Under the action of centrifugation, the solvent with residual monomers is separated from the latex;

[0123] 5. Solvent recovery

[0124] The solvent with residual monomers is flash evaporated by steam stripping. The residual solvent is removed by introducing water vapor at a steam pressure of 0.35 MPa and a vacuum degree of -0.085 MPa to obtain residual monomers;

[0125] 6. Monomer recovery

[0126] All the monomers obtained above are separated and purified by a rectifying column to obtain recovered monomers.

[0127] Example 6

[0128] 1. Pretreatment

[0129] After emulsion polymerization of itaconic acid diethyl ester-isoprene polymer emulsion, wherein the gel content is 35% and the residual itaconic acid diethyl ester monomer is 3.6%, 200 kg of itaconic acid diethyl ester-isoprene polymer emulsion is added into a reaction kettle, 0.3 kg of sodium polysulfide and 0.6 kg of sodium dimethyl dithiocarbamate are added, the temperature is raised to 40°C, vacuum is extracted at -0.09 MPa, and unreacted low-boiling diene, butadiene or isoprene, is removed by flash evaporation;

[0130] 2. Agglomeration

[0131] Agglomerating agent solution preparation: 0.06 kg of methyl carbamate and 0.25 kg of sodium chloride are prepared into a 1% aqueous solution;

[0132] The above agglomerating agent solution is added into the polymer emulsion, the temperature is maintained at 30°C, and stirring is performed for 1.5 h to expand the diameter, water vapor is introduced at a steam pressure of 0.35 MPa, and continuous introduction is performed for 0.5 h; by means of steam shock, temperature rise, and similar compatibility principle, the residual monomer is accelerated to separate from the colloidal particles to monomer droplets;

[0133] 3. Extraction

[0134] In the agglomerated emulsion, 120 kg of ethyl acetate is added, the stirring speed is controlled at 100 rpm, and under strong stirring, extraction is performed for 45 min, the temperature is lowered to 10°C (to reduce the emulsifying capacity of the emulsifier and reduce the residual amount of the solvent), the stirring speed is lowered to 20 rpm, and the extracted monomer is extracted;

[0135] 4. Centrifugal separation

[0136] The extracted emulsion is introduced into a disc centrifuge at a speed of 20 L / min, and the centrifuge rotates at a speed of 5000 rpm, and under the action of centrifugation, the solvent with residual monomers is separated from the latex;

[0137] 5. Solvent recovery

[0138] The solvent with residual monomers is flash evaporated, water vapor is introduced at a steam pressure of 0.35 MPa, and the residual solvent is removed under the condition of vacuum extraction at a vacuum degree of -0.09 MPa to obtain residual monomers;

[0139] 6. Monomer recovery

[0140] All the monomers obtained above are separated and purified through a rectifying column to obtain recovered monomers.

[0141] Example 7

[0142] 1. Pretreatment

[0143] After emulsion polymerization of itaconic acid diethyl ester-isoprene polymer emulsion, wherein the gel content is 35% and the residual itaconic acid diethyl ester monomer is 3.6%, 200 kg of itaconic acid diethyl ester-isoprene polymer emulsion is added into a reaction kettle, 0.3 kg of sodium polysulfide and 0.6 kg of sodium dimethyl dithiocarbamate are added, the temperature is raised to 40°C, vacuum is applied to -0.09 Mpa, flash evaporation is performed to remove unreacted low-boiling diene, butadiene or isoprene;

[0144] 2, agglomeration

[0145] Agglomerating agent solution preparation: 0.03 kg of 150 polyether amine and 0.2 kg of ammonium sulfate are prepared into a 0.5% aqueous solution;

[0146] The above agglomerating agent solution is added into the polymer emulsion, the temperature is maintained at 35°C, and stirring is performed for 1 h to perform size expansion, water vapor is introduced, the vapor pressure is 0.35 Mpa, and the continuous introduction time is 0.4 h; through steam shock, temperature rise, and similar compatibility principle, the residual monomer is accelerated to separate from the colloidal particles to monomer droplets;

[0147] 3, extraction

[0148] 150 kg of benzene is added into the agglomerated emulsion, the stirring speed is controlled at 150 rpm, under strong stirring, extraction is performed for 45 min, the temperature is reduced to 10°C (to reduce the emulsifying capacity of the emulsifier and reduce the residual amount of the solvent), the stirring speed is reduced to 20 rpm, and the extracted monomer is extracted;

[0149] 4, centrifugal separation

[0150] The disc centrifuge is entered at a speed of 20 L / min, and the centrifuge rotates at a speed of 7000 rpm, under the action of centrifugation, the solvent with residual monomer is separated from the latex;

[0151] 5, solvent recovery

[0152] The solvent with residual monomer is flash evaporated, water vapor is introduced, the residual solvent is removed under the conditions of steam pressure of 0.35 Mpa and vacuum degree of -0.095 Mpa, and the residual monomer is obtained;

[0153] 6, monomer recovery

[0154] All the monomers obtained above are separated and purified through a rectifying column to obtain recovered monomers.

[0155] Example 8

[0156] 1, pretreatment

[0157] After emulsion polymerization of itaconic acid diethyl ester-isoprene polymer emulsion, wherein the gel content is 35%, the residual amount of itaconic acid diethyl ester monomer is 3.6%, 200 kg of itaconic acid diethyl ester-isoprene polymer emulsion is added into a reaction kettle, 0.3 kg of sodium polysulfide and 0.6 kg of sodium dimethyl dithiocarbamate are added, the temperature is raised to 40°C, vacuum is extracted at -0.09 Mpa, and unreacted low-boiling diene, butadiene or isoprene, is removed by flash evaporation;

[0158] 2. Agglomeration

[0159] Agglomerating agent solution preparation: 0.2 kg of ammonium oxalate, 0.05 kg of oxalic acid, and 0.02 kg of glyceryl oleate are prepared into a 0.5% aqueous solution;

[0160] The above agglomerating agent solution is added into the polymer emulsion, the temperature is maintained at 35°C, and stirring is performed for 1 h to expand the diameter, water vapor is introduced, the vapor pressure is 0.35 Mpa, and the continuous introduction time is 0.5 h; by means of steam shock, temperature rise, and similar compatibility principle, the residual monomer is accelerated to separate from the colloidal particles to monomer droplets;

[0161] 3. Extraction

[0162] In the agglomerated emulsion, 100 kg of isooctane is added, the stirring speed is controlled at 200 rpm, under strong stirring, extraction is performed for 60 min, the temperature is reduced to 10°C (to reduce the emulsifying capacity of the emulsifier and reduce the residual amount of the solvent), and the stirring speed is reduced to 20 rpm to extract the monomers;

[0163] 4. Centrifugal separation

[0164] The extracted emulsion is introduced into a disc centrifuge at a speed of 10 L / min, and the centrifuge rotates at a speed of 7000 rpm, under the action of centrifugation, the solvent with residual monomers is separated from the latex;

[0165] 5. Solvent recovery

[0166] The solvent with residual monomers is flash evaporated, water vapor is introduced, the residual solvent is removed under the conditions of steam pressure of 0.35 Mpa and vacuum degree of -0.095 Mpa, and the residual monomers are obtained;

[0167] 6. Monomer recovery

[0168] All the monomers obtained above are separated and purified through a rectifying column to obtain the recovered monomers.

[0169] Example 9

[0170] 1. Pretreatment

[0171] After emulsion polymerization of dimethyl fumarate-butadiene polymer emulsion, wherein the gel content is 40% and the dimethyl fumarate residual amount is 4.2%, 200 kg of dimethyl fumarate-butadiene polymer emulsion is added into a reaction kettle, 0.2 kg of sodium nitrite and 0.5 kg of sodium dimethyl dithiocarbamate are added, the temperature is raised to 40°C, vacuum is extracted at -0.085 MPa, and unreacted low-boiling diene, butadiene or isoprene, is removed by flash evaporation;

[0172] 2. Agglomeration

[0173] Agglomerating agent solution preparation: 0.05 kg of methyl carbamate is prepared into a 0.5% aqueous solution;

[0174] The above agglomerating agent solution is added into the polymer emulsion, the temperature is maintained at 35°C, and stirring is performed for 3 h to expand the diameter, water vapor is introduced, the vapor pressure is 0.35 MPa, and the continuous introduction time is 1 h; by means of steam shock, temperature rise, and similar compatibility principle, the residual monomer is accelerated to separate from the colloidal particles to monomer droplets;

[0175] 3. Extraction

[0176] Hexane 260 kg is added into the agglomerated emulsion, the stirring speed is controlled at 150 rpm, under strong stirring, extraction is performed for 45 min, the temperature is lowered to 15°C (to reduce the emulsifying capacity of the emulsifier and reduce the residual amount of the solvent), the stirring speed is lowered to 30 rpm, and the extracted monomers are extracted;

[0177] 4. Centrifugal separation

[0178] The extracted emulsion is introduced into a disc centrifuge at a speed of 20 L / min, the centrifuge rotates at 6000 rpm, and under the action of centrifugation, the solvent with residual monomers is separated from the latex;

[0179] 5. Solvent recovery

[0180] The solvent with residual monomers is flash evaporated, water vapor is introduced, the residual solvent is removed under the conditions of steam pressure 0.35 MPa and vacuum degree -0.085 MPa, and the residual monomers are obtained;

[0181] 6. Monomer recovery

[0182] All the monomers obtained above are separated and purified through a rectifying column to obtain recovered monomers.

[0183] Example 10

[0184] 1. Pretreatment

[0185] After emulsion polymerization of dimethyl fumarate-butadiene polymer emulsion, gel content 40%, dimethyl fumarate residual amount 4.2%, take 200 kg dimethyl fumarate-butadiene polymer emulsion into the reaction kettle, add sodium nitrite 0.2 kg, dimethyl dithiocarbamic acid sodium 0.5 kg, heat to 40 °C, vacuum to -0.085 Mpa, flash distillation, remove unreacted low boiling diene, butadiene or isoprene;

[0186] 2、Agglomeration

[0187] Agglomeration agent solution preparation: sodium acetate 0.08 kg, sodium chloride 0.2 kg, prepare 1% aqueous solution;

[0188] Add the above agglomeration agent solution to the polymer emulsion, maintain the temperature at 30 °C, stir for 2 h, perform diameter expansion, pass water vapor, vapor pressure 0.35 Mpa, continuous passing time 0.5 h; through steam shock, temperature rise, similar compatible principle, accelerate the residual monomer from the colloidal particles to the monomer droplets;

[0189] 3、Extraction

[0190] In the agglomerated emulsion, add petroleum ether 220 kg, control the stirring speed at 130 rpm, under strong stirring, extract for 45 min, cool to 10 °C (reduce the emulsifying ability of emulsifier, reduce the residual amount of solvent), reduce the stirring speed to 20 rpm, extract the monomers;

[0191] 4、Centrifugal separation

[0192] The extracted emulsion enters the disc centrifuge at a speed of 20 L / min, the centrifuge speed is 7000 rpm, under the action of centrifugation, the solvent with residual monomers is separated from the latex;

[0193] 5、Solvent recovery

[0194] Flash steam stripping of the solvent with residual monomers, pass water vapor, remove residual solvent under the conditions of steam pressure 0.35 Mpa, vacuum degree -0.085 Mpa, to obtain residual monomers;

[0195] 6、Monomer recovery

[0196] Separate and purify all the monomers obtained above through a rectification column to obtain recovered monomers.

[0197] Example 11

[0198] 1、Pre-treatment

[0199] After emulsion polymerization of dimethyl fumarate-butadiene polymer emulsion, gel content 40%, dimethyl fumarate residual amount 4.2%, take 200 kg dimethyl fumarate-butadiene polymer emulsion into the reaction kettle, add sodium nitrite 0.2 kg, dimethyl dithiocarbamic acid sodium 0.5 kg, heat to 40 °C, vacuum to -0.085 Mpa, flash distillation, remove unreacted low boiling diene, butadiene or isoprene;

[0200] 2、Agglomeration

[0201] Agglomerant solution preparation: 150 polyether amine 0.05 kg, acetic acid 0.1 kg are prepared into a 0.5% aqueous solution;

[0202] Add the above agglomerant solution to the polymer emulsion, maintain the temperature at 45 °C, stir for 0.5 h, perform diameter expansion, pass in water vapor steam, steam pressure 0.35 Mpa, continuous passing-in time 0.6 h; through steam impact, temperature increase, similar compatibility principle, accelerate the residual monomer from the colloidal particles to the monomer droplets;

[0203] 3、Extraction

[0204] Add toluene 180 kg to the agglomerated emulsion, control the stirring speed at 150 rpm, under strong stirring, extract for 45 min, reduce the temperature to 10 °C (reduce the emulsifying capacity of the emulsifier, reduce the residual amount of solvent), reduce the stirring speed to 20 rpm, extract the monomers freed;

[0205] 4、Centrifugal separation

[0206] The extracted emulsion is introduced into a disc centrifuge at a speed of 10 L / min, the centrifuge speed is 7000 rpm, under the action of centrifugation, the solvent with residual monomers is separated from the latex;

[0207] 5、Solvent recovery

[0208] Flash distillation of the solvent with residual monomers, pass in water vapor, remove the residual solvent under the conditions of steam pressure 0.35 Mpa, vacuum degree -0.095 Mpa, to obtain the residual monomers;

[0209] 6、Monomer recovery

[0210] Separate and purify all the monomers obtained above through a rectification tower to obtain the recovered monomers.

[0211] Example 12

[0212] 1、Pre-treatment

[0213] After emulsion polymerization of dimethyl fumarate-butadiene polymer emulsion, gel content 40%, dimethyl fumarate residual amount 4.2%, take 200 kg dimethyl fumarate-butadiene polymer emulsion into the reaction kettle, add sodium nitrite 0.2 kg, dimethyl dithiocarbamic acid sodium 0.5 kg, heat to 40 °C, vacuum to -0.085 Mpa, flash distillation, remove unreacted low boiling diene, butadiene or isoprene;

[0214] 2、Agglomeration

[0215] Agglomerant solution preparation: amino propylamine dioleate 0.05 kg, glyceryl oleate 0.02 kg, prepare 1% aqueous solution;

[0216] Add the above agglomerant solution to the pretreated emulsion, maintain the temperature at 40 °C, stir for 1 h, perform diameter expansion, pass in dichloromethane steam, steam pressure 0.4 Mpa, continuous passing-in time 0.5 h; through steam impact, temperature increase, similar compatible principle, accelerate the residual monomer from the colloidal particles to the monomer droplets;

[0217] 3、Extraction

[0218] Add dichloromethane 160 kg to the agglomerated emulsion, control the stirring speed at 200 rpm, under strong stirring, extract for 45 min, reduce the temperature to 10 °C (reduce the emulsifying capacity of the emulsifier, reduce the residual amount of solvent), reduce the stirring speed to 20 rpm, extract the monomers freed;

[0219] 4、Centrifugal separation

[0220] Put the extracted emulsion into the disc centrifuge at a speed of 10 L / min, the centrifuge speed is 7000 rpm, under the action of centrifugation, separate the solvent with residual monomers from the latex;

[0221] 5、Solvent recovery

[0222] Flash steam stripping of the solvent with residual monomers, pass in water vapor, steam pressure 0.35 Mpa, remove residual solvent under the condition of vacuum degree -0.095 Mpa, obtain residual monomers;

[0223] 6、Monomer recovery

[0224] Separate and purify all the monomers obtained above through the rectification tower, obtain the recovered monomers.

[0225] Example 13

[0226] 1、Pre-treatment

[0227] 200 kg of dimethyl itaconate-butadiene-glycidyl methacrylate polymer emulsion after emulsion polymerization, wherein the rubber content is 30% and the residual amount of dimethyl itaconate is 3.4%, is added to a reaction kettle, 0.2 kg of sodium nitrite and 0.5 kg of sodium dimethyldithiocarbamate are added, the temperature is raised to 40° C., vacuum is applied to -0.085 MPa, and flash evaporation is performed to remove unreacted low-boiling dienes, butadiene or isoprene;

[0228] 2. Agglomeration

[0229] Agglomerant solution preparation: 0.23 kg of sodium oxalate was prepared into a 1% aqueous solution;

[0230] The agglomerant solution was added to the polymer emulsion, the temperature was maintained at 35°C, and the mixture was stirred for 2 hours. The mixture was then expanded and hexane vapor was introduced at a pressure of 0.25 MPa for 1 hour. The steam shock, temperature increase, and the principle of like dissolves like were used to accelerate the release of residual monomers from the particles to the monomer droplets.

[0231] 3. Extraction

[0232] 300 kg of hexane was added to the agglomerated emulsion, and the stirring speed was controlled at 200 rpm. Under strong stirring, the extraction was carried out for 60 minutes, and the temperature was lowered to 10° C. (to reduce the emulsification ability of the emulsifier and the amount of residual solvent) and the stirring speed was reduced by 30 rpm to extract the free monomers.

[0233] 4. Centrifugal separation

[0234] The extracted emulsion is fed into a disc centrifuge at a speed of 20 L / min and a centrifuge speed of 7000 rpm to separate the solvent containing residual monomers from the latex under centrifugal action;

[0235] 5. Solvent recovery

[0236] The solvent containing the residual monomers was flash stripped, and water vapor was introduced at a steam pressure of 0.35 MPa and a vacuum degree of -0.085 MPa to remove the residual solvent to obtain the residual monomers;

[0237] 6. Monomer recovery

[0238] All the monomers obtained above are separated and purified by a distillation tower to obtain recovered monomers.

[0239] Example 14

[0240] 1. Preprocessing

[0241] Fumaric acid dibutyl ester - butadiene polymer emulsion after emulsion polymerization, wherein the gel content is 34%, the fumaric acid dibutyl ester residual amount is 12.4%, 200 kg of fumaric acid dibutyl ester - butadiene polymer emulsion is added into a reaction kettle, 1.2 kg of sodium dimethyl dithiocarbamate is added, the temperature is raised to 40°C, vacuum is extracted at -0.085 Mpa, flash distillation is performed to remove unreacted low-boiling diene, butadiene or isoprene;

[0242] 2、Agglomeration

[0243] Agglomeration agent solution preparation: 0.12 kg of glyceryl oleate is prepared into a 0.5% aqueous solution;

[0244] The above agglomeration agent solution is added into the polymer emulsion, the temperature is maintained at 35°C, stirring is performed for 2 h, the diameter is expanded, water vapor is introduced, the vapor pressure is 0.35 Mpa, and the continuous introduction time is 1 h; through steam shock, temperature rise, and similar compatibility principle, the residual monomer is accelerated to separate from the colloidal particles to monomer droplets;

[0245] 3、Extraction

[0246] Dichloromethane 180 kg is added into the agglomerated emulsion, the stirring speed is controlled at 150 rpm, under strong stirring, extraction is performed for 60 min, the temperature is reduced to 10°C (to reduce the emulsifying capacity of the emulsifier and reduce the residual amount of the solvent), the stirring speed is reduced to 30 rpm, and the extracted monomers are separated.

[0247] 4、Centrifugal separation

[0248] The extracted emulsion is introduced into a disc centrifuge at a speed of 20 L / min, the centrifuge rotates at 7000 rpm, and under the centrifugal action, the solvent with residual monomers is separated from the latex;

[0249] 5、Solvent recovery

[0250] The solvent with residual monomers is flash distilled, water vapor is introduced, the residual solvent is removed under the conditions of steam pressure 0.35 Mpa and vacuum degree -0.085 Mpa, and the residual monomers are obtained;

[0251] 6、Monomer recovery

[0252] All the monomers obtained above are separated and purified through a rectifying column to obtain recovered monomers.

[0253] Example 15

[0254] 1、Pre-treatment

[0255] 200 kg of diethyl itaconate-butadiene-methacrylic acid polymer emulsion after emulsion polymerization, wherein the rubber content is 50% and the residual amount of diethyl itaconate is 8.5%, is added to a reaction kettle, 0.5 kg of dimethylhydroxylamine is added, the temperature is raised to 40° C., vacuum is applied to -0.09 MPa, and flash evaporation is performed to remove unreacted low-boiling dienes, butadiene or isoprene;

[0256] 2. Agglomeration

[0257] Preparation of agglomerating agent solution: 0.12 kg of sodium oxalate and 2.1 kg of potassium chloride were prepared into a 1% aqueous solution;

[0258] The agglomerant solution was added to the polymer emulsion, the temperature was maintained at 30°C, and the mixture was stirred for 3 hours. The solution was then expanded and steam was introduced at a pressure of 0.35 MPa for 0.5 hours. The steam shock, temperature increase, and the principle of like dissolves like were used to accelerate the release of residual monomers from the colloid particles to the monomer droplets.

[0259] 3. Extraction

[0260] 210 kg of heptane was added to the agglomerated emulsion, and the stirring speed was controlled at 230 rpm. Under strong stirring, the mixture was extracted for 60 min, and then the temperature was lowered to 25° C. (to reduce the emulsification capacity of the emulsifier and the amount of residual solvent) and the stirring speed was reduced by 20 rpm to extract the free monomers.

[0261] 4. Centrifugal separation

[0262] The extracted emulsion is fed into a disc centrifuge at a speed of 20 L / min and a centrifuge speed of 7000 rpm to separate the solvent containing residual monomers from the latex under centrifugal action;

[0263] 5. Solvent recovery

[0264] The solvent containing the residual monomers was flash stripped, and water vapor was introduced at a steam pressure of 0.35 MPa and a vacuum degree of -0.095 MPa to remove the residual solvent to obtain the residual monomers;

[0265] 6. Monomer recovery

[0266] All the monomers obtained above are separated and purified by a distillation tower to obtain recovered monomers.

[0267] Example 16

[0268] 1. Preprocessing

[0269] After emulsion polymerization of dimethyl itaconate-isoprene polymer emulsion, wherein the gel content is 22% and the residual diethyl itaconate is 24%, 200 kg of dimethyl itaconate-isoprene polymer emulsion is added into a reaction kettle, 0.8 kg of sodium nitrite and 1.3 kg of isopropyl hydroxylamine are added, the temperature is raised to 40°C, vacuum is extracted at -0.095 MPa, and unreacted low-boiling diene, butadiene or isoprene, is removed by flash evaporation;

[0270] 2. Agglomeration

[0271] Agglomerating agent solution preparation: 100 polyetheramine 0.15 kg and sodium chloride 0.1 kg are prepared into a 0.5% aqueous solution;

[0272] The above agglomerating agent solution is added to the polymer emulsion, the temperature is maintained at 45°C, and stirring is performed for 1 h to expand the diameter, steam (water vapor or solvent vapor) is introduced at a steam pressure of 0.35 MPa, and continuous introduction is performed for 0.6 h; by steam shock, temperature rise, and similar compatible principles, the residual monomer is accelerated to separate from the colloidal particles to monomer droplets;

[0273] 3. Extraction

[0274] Cyclohexane 300 kg is added to the agglomerated emulsion, and the stirring speed is controlled at 150 rpm. Under strong stirring, extraction is performed for 60 min, the temperature is lowered to 10°C (to reduce the emulsifying capacity of the emulsifier and reduce the residual amount of solvent), and the stirring speed is lowered to 20 rpm to extract the monomers;

[0275] 4. Centrifugal separation

[0276] The extracted emulsion is introduced into a disc centrifuge at a speed of 10 L / min, and the centrifuge rotates at a speed of 7000 rpm. Under the action of centrifugation, the solvent with residual monomers is separated from the latex;

[0277] 5. Solvent recovery

[0278] The solvent with residual monomers is flash evaporated by introducing water vapor at a steam pressure of 0.35 MPa, and the residual solvent is removed under the condition of vacuum extraction at a vacuum degree of -0.095 MPa to obtain residual monomers;

[0279] 6. Monomer recovery

[0280] All the monomers obtained above are separated and purified by a rectifying column to obtain recovered monomers.

[0281] Comparative Example 1

[0282] 1. Pretreatment

[0283] After emulsion polymerization of di-n-butyl itaconate-diene polymer emulsion, wherein the gel content is 25%, the residual amount of di-n-butyl itaconate is 2.8%, 200 kg is added into the reaction kettle, 0.8 kg of isopropyl hydroxylamine is added, the temperature is raised to 35°C, vacuum is extracted at -0.085 Mpa, and unreacted low-boiling diene, butadiene or isoprene is removed by flash evaporation;

[0284] 2. Extraction

[0285] Hexane 200 kg is added, the stirring speed is controlled at 100 rpm, under strong stirring, extraction is carried out for 30 min, the temperature is lowered to 15°C (to reduce the emulsifying ability of the emulsifier and reduce the residual amount of solvent), the stirring speed is lowered to 40 rpm, and the free monomers are extracted;

[0286] 3. Centrifugal separation

[0287] The disc centrifuge is entered at a speed of 15 L / min, the centrifuge rotates at 6000 rpm, and under the action of centrifugation, the solvent with residual monomers is separated from the latex;

[0288] 4. Solvent recovery

[0289] Flash steam stripping is carried out, water vapor is introduced, the steam pressure is 0.35 Mpa, and the residual solvent is removed under the condition of vacuum degree -0.085 Mpa, and the residual monomers are obtained;

[0290] 6. Monomer recovery

[0291] All the monomers obtained above are separated and purified by a rectifying column to obtain recovered monomers.

[0292] Comparative Example 2

[0293] 1. Pretreatment

[0294] After emulsion polymerization of diethyl itaconate-isoprene polymer emulsion, wherein the gel content is 35%, the residual amount of diethyl itaconate monomer is 3.6%, 200 kg is added into the reaction kettle, 0.3 kg of sodium polysulfide and 0.6 kg of sodium dimethyl dithiocarbamate are added, the temperature is raised to 40°C, vacuum is extracted at -0.09 Mpa, and unreacted low-boiling diene, butadiene or isoprene is removed by flash evaporation;

[0295] 2. Extraction

[0296] Hexane 200 kg is added, the stirring speed is controlled at 130 rpm, under strong stirring, extraction is carried out for 45 min, the temperature is lowered to 15°C (to reduce the emulsifying ability of the emulsifier and reduce the residual amount of solvent), the stirring speed is lowered to 30 rpm, and the free monomers are extracted;

[0297] 3. Centrifugal separation

[0298] The solvent with residual monomer and the latex are separated by centrifugation at a speed of 10-25 L / min and a centrifuge speed of 4000-8000 rpm.

[0299] 4. Solvent recovery

[0300] The residual solvent is removed by flash stripping under the conditions of steam pressure of 0.25-0.45 MPa and vacuum degree of -0.075 to -0.095 MPa to obtain residual monomer.

[0301] 6. Monomer recovery

[0302] All the monomers obtained above are separated and purified by a rectifying tower to obtain recovered monomers.

[0303] Comparative Example 3

[0304] 1. Pretreatment

[0305] The emulsion polymerization of dimethyl fumarate-butadiene polymer emulsion, the gel content is 40%, the residual amount of dimethyl fumarate is 4.2%, 200 kg is taken into the reaction kettle, 0.2 kg of sodium nitrite and 0.5 kg of sodium dimethyl dithiocarbamate are added, the temperature is raised to 40°C, vacuum is extracted to -0.085 MPa, and unreacted low-boiling diene, butadiene or isoprene, is removed.

[0306] 2. Extraction

[0307] The solvent is added, and the stirring speed is controlled at 100-200 rpm. Under strong stirring, the extraction is carried out for 20-90 min, and the temperature is lowered to 10-25°C (to reduce the emulsifying ability of the emulsifier and reduce the residual amount of solvent). The stirring speed is reduced to 20-100 rpm, and the free monomer is extracted.

[0308] 3. Centrifugal separation

[0309] The solvent with residual monomer and the latex are separated by centrifugation at a speed of 10-25 L / min and a centrifuge speed of 4000-8000 rpm.

[0310] 4. Solvent recovery

[0311] The residual solvent is removed by flash stripping under the conditions of steam pressure of 0.25-0.45 MPa and vacuum degree of -0.075 to -0.095 MPa to obtain residual monomer.

[0312] 6. Monomer recovery

[0313] All the monomers obtained above are separated and purified by a rectifying tower to obtain recovered monomers.

[0314] Table 1. Extraction results data table for examples and comparative examples

[0315] Extraction rate / % Residual amount in latex / % Recovery amount / kg Extraction amount / kg Loss rate / % Comparative Example 1 55 1.26 2.95064 3.08 4.20 Example 1 95 0.14 5.11784 5.32 3.80 Example 2 91 0.25 4.912544 5.10 3.60 Example 3 88 0.33 4.716096 4.93 4.30 Example 4 94 0.17 5.02712 5.26 4.50 Comparative Example 2 58 1.51 3.975552 4.18 4.80 Example 5 93 0.25 6.408072 6.70 4.30 Example 6 95 0.18 6.45012 6.84 5.70 Example 7 89 0.39 6.05556 6.41 5.50 Example 8 86 0.50 5.808096 6.19 6.20 Comparative Example 3 61 1.64 4.929288 5.12 3.80 Example 9 97 0.13 7.846524 8.15 3.70 Example 10 96 0.17 7.70112 8.06 4.50 Example 11 90 0.42 7.09128 7.56 6.20 Example 12 94 0.25 7.548576 7.90 4.40 Example 13 97 0.102 6.384928 6.60 3.20 Example 14 94 0.74 22.37952 23.31 4.00 Example 15 93 0.60 14.41872 15.81 8.80 Example 16 92 1.92 43.056 44.16 2.50

[0316] The above description of the examples is merely intended to help understand the method of the present application and its core idea. It should be noted that, for those skilled in the art, certain modifications and improvements can be made to the present application without departing from the principles of the present application, and these modifications and improvements also fall within the protection scope of the claims of the present application.

[0317] The above description of the disclosed examples enables those skilled in the art to carry out or use the present application. Various modifications to these examples will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other examples without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these examples shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A process for recovering high-boiling monomers in a bio-based rubber emulsion, comprising the following steps: S1) mixing a bio-based rubber emulsion and a terminating agent, and then performing flash evaporation to obtain a pretreated bio-based rubber emulsion; The bio-based rubber emulsion is selected from the group consisting of di-n-butyl itaconate-butadiene polymer emulsion, dimethyl fumarate-butadiene polymer emulsion, dimethyl itaconate-butadiene-glycidyl methacrylate polymer emulsion, dibutyl fumarate-butadiene polymer emulsion, diethyl itaconate-butadiene-methacrylic acid polymer emulsion, and dimethyl itaconate-isoprene polymer emulsion, with a latex solid content of 20-50 wt%,and a residual high-boiling monomer content of 2-25 wt%; S2) mixing the pretreated bio-based rubber emulsion and an agglomerating agent solution, and then introducing steam; S3) extracting the emulsion obtained in step S2) with an extraction agent to obtain free monomers and an extracted emulsion; S4) centrifugally separating the extracted emulsion to obtain a solvent containing residual monomers and a latex; S5) flash evaporating the solvent containing residual monomers to obtain residual monomers; S6) separating and purifying the residual monomers and free monomers to obtain recovered monomers.

2. The recycling process of claim 1, wherein, The bio-based rubber emulsion is 100 parts by weight, the terminating agent is 0.1-5 parts by weight, the agglomerating agent is 0.01-5 parts by weight, and the extraction agent is 20-1000 parts by weight.

3. The recycling process according to claim 1 or 2, characterized in that, The terminating agent is selected from one or more of sodium polysulfide, nitrite, hydroxylamine compound, and sodium dimethyl dithiocarbamate; The agglomerating agent is selected from one or more of acetic acid, propionic acid, butyric acid, oxalic acid, ammonium sulfate, ammonium carbonate, ammonium bicarbonate, ammonium chloride, ammonium acetate, ammonium oxalate, sodium acetate, sodium oxalate, potassium chloride, sodium chloride, carbamate, methyl carbamate, glyceryl oleate, and polyether amine with a molecular weight of less than 400; The extraction agent is selected from one or more of benzene, toluene, monochloromethane, dichloromethane, carbon disulfide, hexane, heptane, isooctane, dimethylbenzene, petroleum ether, pentane, diethyl ether, and ethyl acetate.

4. The recycling process of claim 1, wherein, In step S1), the flash evaporation is performed at a temperature of 30-45℃, and the flash evaporation is performed under vacuum to a pressure of -0.065 to -0.095 MPa.

5. The recycling process of claim 1, wherein, In step S2), the agglomerating agent solution is an aqueous agglomerating agent solution with a concentration of 0.1-5 wt%, the mixing is performed at a temperature of 30-45℃ for 0.5-4 h with stirring, the steam is water vapor or solvent vapor, the pressure is 0.05-0.45 MPa, and the steam is introduced for 0.2-1.5 h.

6. The recycling process of claim 1, wherein, The average latex particle size of the pretreated bio-based rubber emulsion is 50-150 nm, and the average latex particle size after mixing with the agglomerating agent solution is 200-250 nm.

7. The recycling process of claim 1, wherein, In step S3), the extraction is performed as follows: In the emulsion obtained in step S2), the extraction agent is added, stirring is performed at a speed of 100-230 rpm for 20-90 min, the temperature is reduced to 10-25℃, and stirring is performed at a speed of 20-100 rpm.

8. The recycling process of claim 1, wherein, In step S4), the feed rate for centrifugal separation is 10-25 L / min, and the rotation speed is 4000-8000 rpm.

9. The recycling process of claim 1, wherein, The steam pressure of the flash evaporation in step S5) is 0.25-0.45 MPa, and the vacuum degree is -0.075 to -0.095 MPa.

10. The recycling process of claim 1, wherein, The high-boiling monomer has a boiling point > 200°C.