Recovery process of high-boiling-point monomer in bio-based rubber emulsion

Abstract

The invention provides a process for recovering high-boiling-point monomers in bio-based rubber emulsion, which comprises the following steps: S1) mixing bio-based rubber emulsion and a terminating agent, and carrying out flash evaporation to obtain pretreated bio-based rubber emulsion; s2) mixing the pretreated bio-based rubber emulsion and the agglomerant solution, and then introducing steam; s3) extracting the obtained emulsion by adopting an extracting agent; s4) carrying out centrifugal separation on the extracted extraction emulsion; s5) carrying out flash evaporation and steam stripping on the separated solvent to obtain a residual monomer; and S5) separating and purifying the residual monomer and the free monomer to obtain a recovered monomer. The agglomerating agent is added under an emulsion system, the particle size of colloidal particles is increased, steric hindrance of monomers from an emulsified state to a free state is reduced, and the monomers remaining in the colloidal particles and micelles are dissociated through steam partial pressure; and then selecting a proper extracting agent to extract the free monomer into an extracting solution, and centrifuging to separate out the residual monomer so as to realize the recovery of the monomer.

Description

Technical Field

[0001] The invention relates to the technical field of bio-based rubber preparation, and in particular to a process for recovering high-boiling-point monomers in bio-based rubber latex. Background Art

[0002] Emulsion polymerization is a process in which monomers are dispersed in water to form an emulsion with the help of emulsifiers and mechanical stirring, and then an initiator is added to initiate the polymerization of the monomers. Emulsion polymerization is a method for preparing emulsion materials and solid polymers, but due to the limitations of 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 product application performance, the monomer conversion rate is often controlled at 70-80%. The existing conversion rate of styrene-butadiene rubber and nitrile rubber polymerization process is controlled at about 70% to obtain rubber products with low branching structure. The recovery process of these two 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. After a certain recovery process, the monomer recovery and reuse can be achieved.

[0003] At present, the new generation of bio-based rubber is also prepared by emulsion polymerization technology. Its 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, initiator systems, molecular weight regulators, water and other components. Among them, itaconate and fumarate are high-boiling point monomers. The boiling point of dimethyl itaconate is 208°C, and the boiling point of dibutyl itaconate is 307°C. The emulsion polymerization system is aimed at the treatment of this type of high-boiling point residual monomers. There are no papers and patents that specifically introduce and study the recovery of high-boiling point monomers in emulsion polymerization.

[0004] As mentioned above, currently, small molecular monomers such as butadiene, isoprene, acrylonitrile, etc. in emulsion polymerization can be recovered by conventional flash evaporation or stripping processes due to their low boiling points; for some medium-boiling monomers such as styrene, methyl methacrylate, etc., the monomers remaining in the system can also be recovered by stripping processes; in the pursuit of new materials with high performance and new applications, some special monomers have also been introduced into the emulsion polymerization system. Although the demand problem has been solved to a certain extent, some monomers have high boiling points (boiling points exceeding 200°C), and monomer recovery is difficult. The flash evaporation method cannot reach the boiling point of the monomer, and the monomer removal is difficult. The stripping method cannot meet the conditions for monomer removal, 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) already has the above problems.

[0005] Polymer monomers are the basic raw materials for synthesizing polymers, but some polymer monomers remain in polymer materials during the production process, which has unpredictable effects on product performance and may overflow or be released during processing. These residual polymer monomers are toxic and harmful to a certain extent and may have adverse effects on the environment and human body.

[0006] In addition to conventional flash evaporation and stripping, residual monomers can also be treated by secondary polymerization to reduce the amount of residual monomers and achieve the effect of monomer removal. Among them, Chinese patent application number 201010231458.X provides a method for chemically removing residual monomers from rubber latex. In the process of obtaining rubber latex by emulsion polymerization of monomers, when the monomer conversion rate reaches more than 85%, heating is performed to increase the reaction temperature, and a water-soluble initiator is added under a nitrogen filling pressure of 0.02MPa to 0.04MPa. The reaction time is 1 to 3 hours. The obtained rubber has less impurity content, short degassing time, and high production efficiency. Synthetic rubber latex, but the molecular structure crosslinking and grafting caused by secondary polymerization will seriously affect the product performance, so this method is not suitable for the prepared rubber product system.

[0007] In a study similar to this process technology, a Chinese patent application numbered 201310432984.6 provides a production process for low-VOC polyurethane home decoration coatings, which introduces an extraction process into the polyurethane production process, selects a mixture of 120# gasoline and benzene as an extracting liquid, continuously extracts the free toluene diisocyanate in the polymer component, and then extracts the mixed extract by decompression or presses it into a distillation container with compressed air, and distills the extract by distillation. After distillation, the residue is a mixed liquid of unreacted toluene diisocyanate and a small amount of extracting 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 monomer recovery rate will be very low if only the extraction process is used, because most of the monomers exist in the system in an emulsified form and it is difficult to enter the extracting liquid for separation.

[0008] In summary, in the emulsion polymerization system, it is difficult to recover high-boiling-point monomers. The conventional steam stripping process consumes a large amount of steam and has a low recovery rate. In the emulsion polymerization system, the extraction process has a large steric hindrance from the emulsified state to the free state due to the presence of emulsifiers, 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 of the invention

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

[0010] In view of this, the present application provides a process for recovering high boiling point monomers in bio-based rubber latex, comprising the following steps:

[0011] S1) mixing the bio-based rubber latex and the terminator and flash evaporating the mixture to obtain a pretreated bio-based rubber latex, wherein the bio-based rubber latex has a latex solid content of 1 to 75 wt %, and a high boiling point monomer residual content of 0.01 to 100 wt %;

[0012] S2) mixing the pretreated bio-based rubber latex and agglomerating agent solution and then introducing steam;

[0013] S3) extracting the emulsion obtained in step S2) with an extractant to obtain free monomers and an extracted emulsion;

[0014] S4) centrifuging the extracted emulsion to obtain a solvent and latex containing residual monomers;

[0015] S5) flash stripping the solvent containing the residual monomer to obtain the residual monomer;

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

[0017] Preferably, the bio-based rubber latex is 100 parts by weight, the terminator is 0.1 to 5 parts by weight, the agglomerating agent is 0.01 to 5 parts by weight, and the extractant is 20 to 1000 parts by weight.

[0018] Preferably, the terminator is selected from one or more of sodium polysulfide, nitrite, hydroxylamine compounds and sodium dimethyldithiocarbamate;

[0019] 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, oleyl amino oleate, carbamate, methyl carbamate, aminopropylamine dioleate, oleyl glycerol and polyetheramine with a molecular weight of less than 400;

[0020] The extractant is selected from one or more of benzene, toluene, methyl chloride, dichloromethane, carbon disulfide, hexane, heptane, isooctane, xylene, cyclohexane, petroleum ether, pentane, ether and ethyl acetate.

[0021] Preferably, in step S1), the temperature of the flash evaporation is 30 to 45° C., and the flash evaporation is evacuated to -0.065 to -0.095 MPa.

[0022] Preferably, in step S2), the agglomerating agent solution is an agglomerating agent aqueous solution with a concentration of 0.1 to 5 wt%, the mixing temperature is 30 to 45° C., and the stirring is 0.5 to 4 h; the steam is water vapor or solvent vapor, the pressure is 0.05 to 0.45 MKPa, and the introduction time is 0.2 to 1.5 h.

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

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

[0025] Add an extractant to the emulsion obtained in step S2), stir at a stirring speed of 100-230 rpm for 20-90 min, cool to 10-25° C., and stir at a speed of 20-100 rpm.

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

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

[0028] Preferably, the bio-based rubber latex is selected from 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%, the residual amount of high boiling point monomer is 2-25wt%; the boiling point of the high boiling point monomer is greater than 200°C.

[0029] The present application provides a process for recovering high-boiling-point monomers in a bio-based rubber latex, which firstly mixes the bio-based rubber latex and a terminator and then flashes to obtain a pretreated bio-based rubber latex to remove unreacted low-boiling-point dienes in the bio-based rubber latex, then mixes the pretreated bio-based rubber latex and an agglomerating agent solution and then introduces steam to increase the particle size of the colloid particles in the emulsion through the agglomeration effect of the agglomerating agent, and reduce the steric hindrance of the high-boiling-point monomer from the emulsified state to the free state, and then releases the monomers remaining in the colloid particles and micelles through the steam partial pressure, and then extracts the free monomers through extraction, and then separates the monomer solution from the extracted emulsion after centrifugation, and then flashes the solution containing the residual monomers to obtain the residual monomers, and finally separates and purifies the above-obtained monomers to obtain recovered monomers; thus, the recovery process provided by the present application realizes the effective recovery of high-boiling-point monomers through the above-mentioned 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 invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0031] In view of the problem of high difficulty and low recovery rate of high-boiling-point monomers in bio-based rubber latex in the prior art, the present application provides a process for recovering high-boiling-point monomers in bio-based rubber latex, which adds an agglomerating agent to the bio-based rubber latex system to increase the particle size of the colloid particles, omits the amount of the colloid particle surfactant, reduces the steric hindrance of the high-boiling-point monomers from the emulsified state to the free state, and then releases the monomers remaining in the colloid particles and micelles through steam partial pressure, and then extracts the free monomers into the extract by using a suitable extractant, separates the residual monomers by centrifugation, and realizes monomer recovery. Specifically, the embodiment of the present invention discloses a process for recovering high-boiling-point monomers in bio-based rubber latex, comprising the following steps:

[0032] S1) mixing the bio-based rubber latex and the terminator and flash evaporating the mixture to obtain a pretreated bio-based rubber latex, wherein the bio-based rubber latex has a latex solid content of 1 to 75 wt %, and a high boiling point monomer residual content of 0.01 to 100 wt %;

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

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

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

[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 recovery process provided in the present application is aimed at the recovery of high-boiling monomers in the emulsion generated 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, and the above itaconate esters and fumarate esters 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 tert-butyl carbonate, epoxy resin, vinyl trimethoxy silane and vinyl triisopropoxy silane; the emulsifier, initiator system, molecular weight regulator and water are all conventional emulsion polymerization components.

[0040] In a specific embodiment, the bio-based rubber latex is selected from 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-methacrylate polymer emulsion or dimethyl itaconate-isoprene polymer emulsion; wherein the solid content of the latex is 1-75wt%, and the residual amount of high boiling point monomer is 0.01-100wt%, specifically, the solid content of the latex is 20-50wt%, and the residual amount of high boiling point monomer is 2-25wt%; the boiling point of the high boiling point monomer is greater than 200°C.

[0041] The present application first pre-treats the bio-based rubber latex to remove unreacted low-boiling dienes, such as butadiene and isoprene; specifically:

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

[0043] A terminator is added in the above pretreatment to prevent further reaction of residual monomers in the emulsion, eliminate free radical activity, and avoid self-polymerization and graft polymerization. The terminator is selected from one or more of sodium polysulfide, nitrite, hydroxylamine compounds and sodium dimethyldithiocarbamate. Specifically, the terminator is selected from one or two of isopropylhydroxylamine, sodium polysulfide, sodium dimethyldithiocarbamate, dimethylhydroxylamine and sodium nitrite. During the above pretreatment, the flash evaporation temperature is 35 to 40°C, and the vacuum degree is -0.085 to -0.090MPa.

[0044] According to the present invention, the pretreated bio-based rubber latex and agglomerant solution are then mixed for agglomeration, and then steam is introduced; the average particle size of the bio-based rubber latex is 50-150nm, and the latex particle size is increased to 200-350nm through the agglomeration process to facilitate the release of high-boiling point monomers from micelles; the agglomerant is selected from weak acids, weak acid salts, and inorganic salts, which mainly act on the emulsifier system, reduce the stability of the emulsification system, and provide the possibility of two micelles to coalesce; the ester group and amino compound are used to pull the micelles together through bridging to achieve the effect of agglomeration. In order to ensure the free effect of the monomer, the latex is further treated by introducing water vapor, solvent vapor, etc., to give the latex enough temperature or free space, and accelerate 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, oleyl amino oleate, carbamate, methyl carbamate, aminopropylamine dioleate, oleyl 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, oleyl amino oleate, potassium chloride, polyetheramine, sodium chloride, ammonium oxalate, methyl carbamate, ammonium sulfate, oxalic acid, oleyl glyceride, ammonium acetate and aminopropylamine dioleate. The agglomerating agent solution is a 0.1-5wt% agglomerating agent aqueous solution, specifically, the agglomerating agent solution is a 0.5-3wt% agglomerating agent aqueous solution, more specifically, the agglomerating agent solution is a 0.8-1wt% 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 0.5-4h for agglomeration, and then steam is introduced at a steam pressure of 0.05-0.45MPa for 0.2-1.5h.

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

[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 present application then extracts the obtained emulsion with an extractant to obtain free monomers and extracted emulsion; wherein, the extractant selects an organic solvent that is immiscible with water as the extractant, which is easy to stratify under centrifugal or static conditions, thereby achieving the purpose of extraction, and the extractant has a low boiling point and is easy to separate from the extracted monomer to achieve the purpose of monomer refining and recovery. The extractant is one or more of benzene, toluene, chloroform, dichloromethane, carbon disulfide, hexane, heptane, isooctane, xylene, cyclohexane, petroleum ether, pentane, ether and ethyl acetate; specifically, the extractant is selected from hexane, pentane, cyclohexane, carbon disulfide, ethyl acetate, benzene, isooctane, petroleum ether, dichloromethane or heptane. The above extraction process is specifically as follows:

[0049] Add an extractant to the emulsion, stir at a speed of 100 to 230 rpm, extract for 20 to 90 minutes, cool to 10 to 25°C (to reduce the emulsifying ability of the emulsifier and the amount of residual solvent), reduce the stirring speed by 20 to 100 rpm, and extract the free monomer.

[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 cooling is to 15-20° C., the stirring speed is 30-80 rpm, and more specifically, the cooling is to 16-18° C., the stirring speed is 40-60 rpm.

[0051] According to the present invention, the extracted emulsion is then centrifuged to separate the solvent containing residual monomers from the latex under centrifugal action; the feed rate of the centrifugal separation is 10 to 25 L / min, and the rotation speed is 4000 to 8000 rpm. Specifically, the feed rate of the centrifugal separation is 12 to 20 L / min, and the rotation speed is 5000 to 7000 rpm. More specifically, the feed rate of the centrifugal separation is 15 to 18 L / min, and the rotation speed is 6000 to 6800 rpm.

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

[0053] Finally, the present application purifies the above-mentioned residual monomers and free monomers to obtain recovered monomers; the purification is carried out according to methods well known to those skilled in the art, and the present application has no particular limitation on this.

[0054] In the process of recovering high-boiling-point monomers in the present application, the bio-based rubber latex is 100 parts by weight, the terminator is 0.1 to 5 parts by weight, the agglomerating agent is 0.01 to 5 parts by weight, and the extracting agent is 20 to 1000 parts by weight; specifically, the content of the terminator is 0.25 to 4 parts by weight, specifically, the content of the terminator is 0.35 to 3 parts by weight, specifically, the content of the terminator is 0.4 to 2 parts by weight, specifically, the content of the terminator is 0.45 to 1.05 parts by weight, specifically, the content of the terminator is 0.6 to 1.0 parts by weight; specifically, the content of the agglomerating agent is 0.035 to 4 parts by weight. Part by weight, more specifically, the content of the agglomerating agent is 0.065-3 parts by weight; illustratively, the content of the agglomerating 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 part 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, specifically 180-220 parts by weight.

[0055] The present application provides a process for recovering high-boiling-point monomers in bio-based rubber latex, wherein the reason why the extraction of high-boiling-point monomers is difficult is that the particle size is small and the micelles wrap the monomers. The present application implements an agglomeration process by adding an agglomerating agent to achieve the enlargement of the micelle particles, reduce the attachment of the emulsifier on the surface of the micelle particles, and allow the high-boiling-point monomers to be freed; the steam contacts the monomers to increase the system temperature to accelerate the monomer release, and at the same time, the steam can drive the monomers to move from the micelles to the outside of the micelles and be freed from the micelles; the subsequent extraction uses a low-boiling-point solvent and completes the monomer extraction through high-temperature extraction; finally, centrifugation is performed to separate the solvent from the emulsion, and the recovered monomers with a high recovery rate are obtained after purification.

[0056] In order to further understand the present invention, the recovery process of high boiling point monomers in the bio-based rubber latex provided by the present invention is described in detail below in conjunction with the examples, and the protection scope of the present invention is not limited by the following examples.

[0057] Example 1

[0058] 1. Preprocessing

[0059] After emulsion polymerization, 200 kg of di-n-butyl itaconate-butadiene polymer emulsion, wherein the rubber content is 25% and the residual amount of di-n-butyl itaconate is 2.8%, is added into a reaction kettle, 0.8 kg of isopropylhydroxylamine is added, the temperature is raised to 35° C., vacuumized to -0.085 MPa, and flash distilled to remove unreacted low-boiling dienes, butadiene or isoprene;

[0060] 2. Agglomeration

[0061] Preparation of agglomerating agent solution: Prepare 0.03 kg of acetic acid and 0.1 kg of ammonium acetate into a 1% aqueous solution:

[0062] The agglomerating agent solution was added to the pretreated polymer emulsion, the temperature was maintained at 35°C, stirred for 1 hour, the diameter was expanded, and hexane steam was introduced at a steam pressure of 0.3 MPa for a continuous introduction time of 0.5 hours; the residual monomer was accelerated to be freed from the colloid particles to the monomer droplets through steam shock, temperature increase, and the principle of similar compatibility;

[0063] 3. Extraction

[0064] Add 200 kg of hexane to the agglomerated emulsion, control the stirring speed to 100 rpm, extract for 30 min under strong stirring, cool to 15° C. (to reduce the emulsification ability of the emulsifier and the residual amount of the solvent), reduce the stirring speed to 40 rpm, and extract the free monomers;

[0065] 4. Centrifugal separation

[0066] The extracted emulsion is fed into a disc centrifuge at a speed of 15 L / min and a centrifuge speed of 6000 rpm. 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 stripped, water vapor is introduced, the vapor pressure is 0.35 MPa, and the vacuum degree is -0.085 MPa to remove the solvent to obtain residual monomers;

[0069] 6. Monomer recovery

[0070] All the monomers obtained above are separated and purified by a distillation tower to obtain recovered monomers.

[0071] Example 2

[0072] 1. Preprocessing

[0073] After emulsion polymerization, 200 kg of di-n-butyl itaconate-butadiene polymer emulsion, wherein the rubber content is 25% and the residual amount of di-n-butyl itaconate is 2.8%, is added into a reaction kettle, 0.8 kg of isopropylhydroxylamine is added, the temperature is raised to 35° C., vacuumized to -0.085 MPa, and flash distilled to remove unreacted low-boiling dienes, butadiene or isoprene;

[0074] 2. Agglomeration

[0075] Agglomerating agent solution preparation: 0.04 kg of amino oleate and 0.2 kg of potassium chloride are prepared into a 0.5% aqueous solution;

[0076] Add the agglomerating agent solution to the polymer emulsion, maintain the temperature at 30°C, stir for 1.5 hours, expand the diameter, and introduce water vapor with a steam pressure of 0.35 MPa for 0.2 hours; accelerate the release of residual monomers from the colloid particles to the monomer droplets through steam shock, temperature increase, and similar compatibility principle;

[0077] 3. Extraction

[0078] Add 200 kg of pentane to the agglomerated emulsion, control the stirring speed to 100 rpm, extract for 30 min under strong stirring, cool to 15° C. (to reduce the emulsification ability of the emulsifier and the residual amount of the solvent), reduce the stirring speed by 30 rpm, and extract the free monomers;

[0079] 4. Centrifugal separation

[0080] The extracted emulsion is fed into a disc centrifuge at a speed of 15 L / min and a centrifuge 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 stripped, water vapor is introduced, the vapor pressure is 0.35 MPa, and the vacuum degree is -0.085 MPa to remove the solvent to obtain residual monomers;

[0083] 6. Monomer recovery

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

[0085] Example 3

[0086] 1. Preprocessing

[0087] After emulsion polymerization, 200 kg of di-n-butyl itaconate-butadiene polymer emulsion, wherein the rubber content is 25% and the residual amount of di-n-butyl itaconate is 2.8%, is added into a reaction kettle, 0.8 kg of isopropylhydroxylamine is added, the temperature is raised to 35° C., vacuumized to -0.085 MPa, and flash distilled 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 are prepared into a 0.5% aqueous solution;

[0090] The agglomerating agent solution was added to the pretreated polymer emulsion, the temperature was maintained at 35°C, stirred for 1 hour, the diameter was expanded, and water vapor was introduced at a steam pressure of 0.35 MPa for a continuous introduction time of 0.4 hours; the residual monomer was accelerated to be freed from the colloid particles to the monomer droplets through steam shock, temperature increase, and the principle of similar compatibility;

[0091] 3. Extraction

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

[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. Under the action of centrifugation, the solvent with residual monomers is separated from the latex.

[0095] 5. Solvent recovery

[0096] The solvent with residual monomers is flash stripped, and water vapor is introduced at a steam pressure of 0.35 MPa and a vacuum degree of -0.09 MPa to remove the residual solvent to obtain 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, 200 kg of di-n-butyl itaconate-butadiene polymer emulsion, wherein the rubber content is 25% and the residual amount of di-n-butyl itaconate is 2.8%, is added into a reaction kettle, 0.8 kg of isopropylhydroxylamine is added, the temperature is raised to 35° C., vacuumized to -0.085 MPa, and flash distilled to remove unreacted low-boiling dienes, butadiene or isoprene;

[0102] 2. Agglomeration

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

[0104] The agglomerating agent solution was added to the pretreated polymer emulsion, the temperature was maintained at 35°C, stirred for 1 hour, and the diameter was expanded. Carbon disulfide vapor was introduced at a steam pressure of 0.15 MPa for a continuous introduction time of 0.4 hours. The residual monomer was accelerated to be freed from the colloid particles to the monomer droplets through steam shock, temperature increase, and similar compatibility principle.

[0105] 3. Extraction

[0106] Add 100 kg of carbon disulfide to the agglomerated emulsion, control the stirring speed to 200 rpm, extract for 60 min under strong stirring, cool to 10° C. (to reduce the emulsifying ability of the emulsifier and the residual amount of the solvent), reduce the stirring speed by 20 rpm, and extract the free monomers;

[0107] 4. Centrifugal separation

[0108] The extracted emulsion is fed into a disc centrifuge at a speed of 10 L / min and a centrifuge speed of 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 stripped, and water vapor is introduced at a steam pressure of 0.35 MPa and a vacuum degree of -0.095 MPa to remove the residual solvent to obtain residual monomers;

[0111] 6. Monomer recovery

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

[0113] Example 5

[0114] 1. Preprocessing

[0115] 200 kg of diethyl itaconate-isoprene polymer emulsion after emulsion polymerization, wherein the rubber content is 35% and the residual amount of diethyl itaconate monomer is 3.6%, is added into a reaction kettle, 0.3 kg of sodium polysulfide and 0.6 kg of sodium dimethyldithiocarbamate are added, the temperature is raised to 40° C., vacuumized to -0.09 MPa, and flash distilled to remove unreacted low-boiling dienes, butadiene or isoprene;

[0116] 2. Agglomeration

[0117] Preparation of agglomerating agent solution: 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] Add agglomerating agent to the polymer emulsion, maintain the temperature at 35°C, stir for 1 hour, expand the diameter, and introduce water vapor with a steam pressure of 0.35Mpa for 1 hour; accelerate the release of residual monomers from the colloid particles to the monomer droplets through steam shock, temperature increase, and similar compatibility principle;

[0119] 3. Extraction

[0120] Add 200 kg of hexane to the agglomerated emulsion, control the stirring speed to 130 rpm, extract for 45 min under strong stirring, cool to 15° C. (to reduce the emulsification ability of the emulsifier and the residual amount of the solvent), reduce the stirring speed by 30 rpm, and extract the free monomers;

[0121] 4. Centrifugal separation

[0122] The extracted emulsion is fed into a disc centrifuge at a speed of 15 L / min and a centrifuge speed of 6000 rpm to separate the solvent containing residual monomers from the latex under the action of centrifugation;

[0123] 5. Solvent recovery

[0124] The solvent with residual monomers is flash stripped, and water vapor is introduced at a steam pressure of 0.35 MPa and a vacuum degree of -0.085 MPa to remove the residual solvent to obtain residual monomers;

[0125] 6. Monomer recovery

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

[0127] Example 6

[0128] 1. Preprocessing

[0129] 200 kg of diethyl itaconate-isoprene polymer emulsion after emulsion polymerization, wherein the rubber content is 35% and the residual amount of diethyl itaconate monomer is 3.6%, is added into a reaction kettle, 0.3 kg of sodium polysulfide and 0.6 kg of sodium dimethyldithiocarbamate are added, the temperature is raised to 40° C., vacuumized to -0.09 MPa, and flash distilled to remove unreacted low-boiling dienes, butadiene or isoprene;

[0130] 2. Agglomeration

[0131] Preparation of agglomerating agent solution: 0.06 kg of methyl carbamate and 0.25 kg of sodium chloride were prepared into a 1% aqueous solution;

[0132] Add the agglomerating agent solution to the polymer emulsion, maintain the temperature at 30°C, stir for 1.5 hours, expand the diameter, and introduce water vapor with a steam pressure of 0.35 MPa for 0.5 hours; accelerate the release of residual monomers from the colloid particles to the monomer droplets through steam shock, temperature increase, and similar compatibility principle;

[0133] 3. Extraction

[0134] Add 120 kg of ethyl acetate to the agglomerated emulsion, control the stirring speed to 100 rpm, extract for 45 min under strong stirring, cool to 10° C. (to reduce the emulsification ability of the emulsifier and the residual amount of the solvent), reduce the stirring speed by 20 rpm, and extract the free monomer;

[0135] 4. Centrifugal separation

[0136] The extracted emulsion is fed into a disc centrifuge at a speed of 20 L / min and a centrifuge speed of 5000 rpm. 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 stripped, and water vapor is introduced at a steam pressure of 0.35 MPa and a vacuum degree of -0.09 MPa to remove the residual solvent to obtain residual monomers;

[0139] 6. Monomer recovery

[0140] All the monomers obtained above are separated and purified by a distillation tower to obtain recovered monomers.

[0141] Example 7

[0142] 1. Preprocessing

[0143] 200 kg of diethyl itaconate-isoprene polymer emulsion after emulsion polymerization, wherein the rubber content is 35% and the residual amount of diethyl itaconate monomer is 3.6%, is added into a reaction kettle, 0.3 kg of sodium polysulfide and 0.6 kg of sodium dimethyldithiocarbamate are added, the temperature is raised to 40° C., vacuumized to -0.09 MPa, and flash distilled to remove unreacted low-boiling dienes, butadiene or isoprene;

[0144] 2. Agglomeration

[0145] Preparation of agglomerating agent solution: 0.03 kg of 150 polyetheramine and 0.2 kg of ammonium sulfate are prepared into a 0.5% aqueous solution;

[0146] Add the agglomerating agent solution to the polymer emulsion, maintain the temperature at 35°C, stir for 1 hour, expand the diameter, and introduce water vapor with a steam pressure of 0.35 MPa for 0.4 hours; accelerate the release of residual monomers from the colloid particles to the monomer droplets through steam shock, temperature increase, and the principle of similar compatibility;

[0147] 3. Extraction

[0148] Add 150 kg of benzene to the agglomerated emulsion, control the stirring speed to 150 rpm, extract for 45 min under strong stirring, cool to 10° C. (to reduce the emulsification capacity of the emulsifier and the residual amount of the solvent), reduce the stirring speed by 20 rpm, and extract the free monomer;

[0149] 4. Centrifugal separation

[0150] Enter the disc centrifuge at a speed of 20L / min and a centrifuge speed of 7000rpm to separate the solvent with residual monomers from the latex under the action of centrifugation;

[0151] 5. Solvent recovery

[0152] The solvent with residual monomers is flash stripped, and water vapor is introduced at a steam pressure of 0.35 MPa and a vacuum degree of -0.095 MPa to remove the residual solvent to obtain residual monomers;

[0153] 6. Monomer recovery

[0154] All the monomers obtained above are separated and purified by a distillation tower to obtain recovered monomers.

[0155] Example 8

[0156] 1. Preprocessing

[0157] 200 kg of diethyl itaconate-isoprene polymer emulsion after emulsion polymerization, wherein the rubber content is 35% and the residual amount of diethyl itaconate monomer is 3.6%, is added into a reaction kettle, 0.3 kg of sodium polysulfide and 0.6 kg of sodium dimethyldithiocarbamate are added, the temperature is raised to 40° C., vacuumized to -0.09 MPa, and flash distilled to remove unreacted low-boiling dienes, butadiene or isoprene;

[0158] 2. Agglomeration

[0159] Preparation of agglomerating agent solution: 0.2 kg of ammonium oxalate, 0.05 kg of oxalic acid and 0.02 kg of oleyl glyceride were prepared into a 0.5% aqueous solution;

[0160] Add the agglomerating agent solution to the polymer emulsion, maintain the temperature at 35°C, stir for 1 hour, expand the diameter, and introduce water vapor with a steam pressure of 0.35 MPa for 0.5 hour; accelerate the release of residual monomers from the colloid particles to the monomer droplets through steam shock, temperature increase, and similar compatibility principle;

[0161] 3. Extraction

[0162] Add 100 kg of isooctane to the agglomerated emulsion, control the stirring speed to 200 rpm, extract for 60 min under strong stirring, cool to 10° C. (to reduce the emulsifying ability of the emulsifier and the residual amount of the solvent), reduce the stirring speed by 20 rpm, and extract the free monomers;

[0163] 4. Centrifugal separation

[0164] The extracted emulsion is fed into a disc centrifuge at a speed of 10 L / min and a centrifuge 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 stripped, and water vapor is introduced at a steam pressure of 0.35 MPa and a vacuum degree of -0.095 MPa to remove the residual solvent to obtain residual monomers;

[0167] 6. Monomer recovery

[0168] All the monomers obtained above are separated and purified by a distillation tower to obtain recovered monomers.

[0169] Example 9

[0170] 1. Preprocessing

[0171] 200 kg of dimethyl fumarate-butadiene polymer emulsion after emulsion polymerization, wherein the rubber content is 40% and the residual amount of dimethyl fumarate is 4.2%, is added into 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., vacuumized to -0.085 MPa, and flash distilled to remove unreacted low-boiling dienes, butadiene or isoprene;

[0172] 2. Agglomeration

[0173] Preparation of agglomerating agent solution: 0.05 kg of methyl carbamate was prepared into a 0.5% aqueous solution;

[0174] Add the agglomerating agent solution to the polymer emulsion, maintain the temperature at 35°C, stir for 3 hours, expand the diameter, and introduce water vapor with a steam pressure of 0.35 MPa for 1 hour; accelerate the release of residual monomers from the colloid particles to the monomer droplets through steam shock, temperature increase, and the principle of similar compatibility;

[0175] 3. Extraction

[0176] Add 260 kg of hexane to the agglomerated emulsion, control the stirring speed to 150 rpm, extract for 45 min under strong stirring, cool to 15° C. (to reduce the emulsifying ability of the emulsifier and the residual amount of the solvent), reduce the stirring speed by 30 rpm, and extract the free monomers;

[0177] 4. Centrifugal separation

[0178] The extracted emulsion is fed into a disc centrifuge at a speed of 20 L / min and a centrifuge speed of 6000 rpm. 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 stripped, and water vapor is introduced at a steam pressure of 0.35 MPa and a vacuum degree of -0.085 MPa to remove the residual solvent to obtain residual monomers;

[0181] 6. Monomer recovery

[0182] All the monomers obtained above are separated and purified by a distillation tower to obtain recovered monomers.

[0183] Example 10

[0184] 1. Preprocessing

[0185] After emulsion polymerization, 200 kg of dimethyl fumarate-butadiene polymer emulsion with a rubber content of 40% and a residual amount of dimethyl fumarate of 4.2% is added to a reaction kettle, and 0.2 kg of sodium nitrite and 0.5 kg of sodium dimethyldithiocarbamate are added. The temperature is raised to 40° C., and the vacuum is drawn to -0.085 MPa for flash evaporation to remove unreacted low-boiling dienes, butadiene or isoprene;

[0186] 2. Agglomeration

[0187] Preparation of agglomerating agent solution: 0.08 kg of sodium acetate and 0.2 kg of sodium chloride are prepared into a 1% aqueous solution;

[0188] Add the agglomerating agent solution to the polymer emulsion, maintain the temperature at 30°C, stir for 2 hours, expand the diameter, and introduce water vapor with a steam pressure of 0.35 MPa for 0.5 hours; accelerate the release of residual monomers from the colloid particles to the monomer droplets through steam shock, temperature increase, and similar compatibility principle;

[0189] 3. Extraction

[0190] Add 220 kg of petroleum ether to the agglomerated emulsion, control the stirring speed to 130 rpm, extract for 45 min under strong stirring, cool to 10° C. (to reduce the emulsification ability of the emulsifier and the residual amount of the solvent), reduce the stirring speed by 20 rpm, and extract the free monomer;

[0191] 4. Centrifugal separation

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

[0193] 5. Solvent recovery

[0194] The solvent with residual monomers is flash stripped, and water vapor is introduced at a steam pressure of 0.35 MPa and a vacuum degree of -0.085 MPa to remove the residual solvent to obtain residual monomers;

[0195] 6. Monomer recovery

[0196] All the monomers obtained above are separated and purified by a distillation tower to obtain recovered monomers.

[0197] Embodiment 11

[0198] 1. Preprocessing

[0199] After emulsion polymerization, 200 kg of dimethyl fumarate-butadiene polymer emulsion with a rubber content of 40% and a residual amount of dimethyl fumarate of 4.2% is added to a reaction kettle, and 0.2 kg of sodium nitrite and 0.5 kg of sodium dimethyldithiocarbamate are added. The temperature is raised to 40° C., and the vacuum is drawn to -0.085 MPa for flash evaporation to remove unreacted low-boiling dienes, butadiene or isoprene;

[0200] 2. Agglomeration

[0201] Preparation of agglomerating agent solution: 0.05 kg of 150 polyetheramine and 0.1 kg of acetic acid are prepared into a 0.5% aqueous solution;

[0202] Add the agglomerating agent solution to the polymer emulsion, maintain the temperature at 45°C, stir for 0.5h, expand the diameter, and introduce water vapor at a steam pressure of 0.35Mpa for 0.6h; accelerate the release of residual monomers from the colloid particles to the monomer droplets through steam shock, temperature increase, and similar compatibility principle;

[0203] 3. Extraction

[0204] Add 180 kg of toluene to the agglomerated emulsion, control the stirring speed to 150 rpm, extract for 45 min under strong stirring, cool to 10° C. (to reduce the emulsification capacity of the emulsifier and the residual amount of the solvent), reduce the stirring speed by 20 rpm, and extract the free monomer;

[0205] 4. Centrifugal separation

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

[0207] 5. Solvent recovery

[0208] The solvent with residual monomers is flash stripped, and water vapor is introduced at a steam pressure of 0.35 MPa and a vacuum degree of -0.095 MPa to remove the residual solvent to obtain residual monomers;

[0209] 6. Monomer recovery

[0210] All the monomers obtained above are separated and purified by a distillation tower to obtain recovered monomers.

[0211] Example 12

[0212] 1. Preprocessing

[0213] After emulsion polymerization, 200 kg of dimethyl fumarate-butadiene polymer emulsion with a rubber content of 40% and a residual amount of dimethyl fumarate of 4.2% is added to a reaction kettle, and 0.2 kg of sodium nitrite and 0.5 kg of sodium dimethyldithiocarbamate are added. The temperature is raised to 40° C., and the vacuum is drawn to -0.085 MPa for flash evaporation to remove unreacted low-boiling dienes, butadiene or isoprene;

[0214] 2. Agglomeration

[0215] Preparation of agglomerating agent solution: 0.05 kg of aminopropylamine dioleate and 0.02 kg of oleic acid glyceride are prepared into a 1% aqueous solution;

[0216] Add the agglomerating agent solution to the pretreated emulsion, maintain the temperature at 40°C, stir for 1 hour, expand the diameter, and introduce dichloromethane steam with a steam pressure of 0.4 MPa for 0.5 hour; accelerate the release of residual monomers from the colloid particles to the monomer droplets through steam shock, temperature increase, and similar compatibility principle;

[0217] 3. Extraction

[0218] Add 160 kg of dichloromethane to the agglomerated emulsion, control the stirring speed to 200 rpm, extract for 45 min under strong stirring, cool to 10° C. (to reduce the emulsification ability of the emulsifier and the residual amount of the solvent), reduce the stirring speed by 20 rpm, and extract the free monomer;

[0219] 4. Centrifugal separation

[0220] The extracted emulsion is fed into a disc centrifuge at a speed of 10 L / min and a centrifuge speed of 7000 rpm. Under the action of centrifugation, the solvent with residual monomers is separated from the latex;

[0221] 5. Solvent recovery

[0222] The solvent with residual monomers is flash stripped, and water vapor is introduced at a steam pressure of 0.35 MPa and a vacuum degree of -0.095 MPa to remove the residual solvent to obtain residual monomers;

[0223] 6. Monomer recovery

[0224] All the monomers obtained above are separated and purified by a distillation tower to obtain recovered monomers.

[0225] Example 13

[0226] 1. Preprocessing

[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 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., vacuumized to -0.085 MPa, and flash distillation is performed to remove unreacted low-boiling dienes, butadiene or isoprene;

[0228] 2. Agglomeration

[0229] Agglomerating agent solution preparation: 0.23 kg of sodium oxalate is prepared into a 1% aqueous solution;

[0230] Add the agglomerating agent solution to the polymer emulsion, maintain the temperature at 35°C, stir for 2 hours, expand the diameter, and introduce hexane steam at a steam pressure of 0.25 MPa for 1 hour; accelerate the release of residual monomers from the colloid particles to the monomer droplets through steam shock, temperature increase, and the principle of similar compatibility;

[0231] 3. Extraction

[0232] Add 300 kg of hexane to the agglomerated emulsion, control the stirring speed to 200 rpm, extract for 60 min under strong stirring, cool to 10° C. (to reduce the emulsification ability of the emulsifier and the residual amount of the solvent), reduce the stirring speed by 30 rpm, and 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. Under the action of centrifugation, the solvent with residual monomers is separated from the latex;

[0235] 5. Solvent recovery

[0236] The solvent with residual monomers is flash stripped, and water vapor is introduced at a steam pressure of 0.35 MPa and a vacuum degree of -0.085 MPa to remove the residual solvent to obtain 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] Embodiment 14

[0240] 1. Preprocessing

[0241] 200 kg of dibutyl fumarate-butadiene polymer emulsion after emulsion polymerization, wherein the rubber content is 34% and the residual amount of dibutyl fumarate is 12.4%, is added into a reaction kettle, 1.2 kg of sodium dimethyldithiocarbamate is added, the temperature is raised to 40° C., vacuumized to -0.085 MPa, and flash distilled to remove unreacted low-boiling dienes, butadiene or isoprene;

[0242] 2. Agglomeration

[0243] Preparation of agglomerating agent solution: 0.12 kg of olein was prepared into a 0.5% aqueous solution;

[0244] Add the agglomerating agent solution to the polymer emulsion, maintain the temperature at 35°C, stir for 2 hours, expand the diameter, and introduce water vapor with a steam pressure of 0.35 MPa for 1 hour; accelerate the release of residual monomers from the colloid particles to the monomer droplets through steam shock, temperature increase, and the principle of similar compatibility;

[0245] 3. Extraction

[0246] 180 kg of dichloromethane was added to the agglomerated emulsion, the stirring speed was controlled at 150 rpm, and the extraction was performed for 60 min under strong stirring. The temperature was lowered to 10° C. (to reduce the emulsifying ability of the emulsifier and the residual amount of the solvent), and the stirring speed was lowered by 30 rpm to extract the free monomers.

[0247] 4. Centrifugal separation

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

[0249] 5. Solvent recovery

[0250] The solvent with residual monomers is flash stripped, and water vapor is introduced at a steam pressure of 0.35 MPa and a vacuum degree of -0.085 MPa to remove the residual solvent to obtain residual monomers;

[0251] 6. Monomer recovery

[0252] All the monomers obtained above are separated and purified by a distillation tower to obtain recovered monomers.

[0253] Embodiment 15

[0254] 1. Preprocessing

[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 into a reaction kettle, 0.5 kg of dimethylhydroxylamine is added, the temperature is raised to 40° C., vacuumized to -0.09 MPa, and flash distillation 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 are prepared into a 1% aqueous solution;

[0258] Add the above agglomerating agent solution to the polymer emulsion, maintain the temperature at 30°C, stir for 3 hours, expand the diameter, and introduce water vapor with a steam pressure of 0.35 MPa for 0.5 hours; accelerate the release of residual monomers from the colloid particles to the monomer droplets through steam shock, temperature increase, and similar compatibility principle;

[0259] 3. Extraction

[0260] Add 210 kg of heptane to the agglomerated emulsion, control the stirring speed to 230 rpm, extract for 60 min under strong stirring, cool to 25° C. (to reduce the emulsification ability of the emulsifier and the residual amount of the solvent), reduce the stirring speed by 20 rpm, and 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. Under the action of centrifugation, the solvent with residual monomers is separated from the latex;

[0263] 5. Solvent recovery

[0264] The solvent with residual monomers is flash stripped, and water vapor is introduced at a steam pressure of 0.35 MPa and a vacuum degree of -0.095 MPa to remove the residual solvent to obtain 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, the dimethyl itaconate-isoprene polymer emulsion has a rubber content of 22% and a residual amount of diethyl itaconate of 24%. 200 kg of the dimethyl itaconate-isoprene polymer emulsion is added to a reaction kettle, 0.8 kg of sodium nitrite and 1.3 kg of isopropylhydroxylamine are added, the temperature is raised to 40° C., vacuumized to -0.095 MPa, and flash distilled to remove unreacted low-boiling dienes, butadiene or isoprene;

[0270] 2. Agglomeration

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

[0272] Add the agglomerating agent solution to the polymer emulsion, maintain the temperature at 45°C, stir for 1 hour, expand the diameter, and introduce steam (water vapor or solvent vapor) at a steam pressure of 0.35 MPa for a continuous introduction time of 0.6 hours; accelerate the release of residual monomers from colloid particles to monomer droplets through steam shock, temperature increase, and similar compatibility principle;

[0273] 3. Extraction

[0274] Add 300 kg of cyclohexane to the agglomerated emulsion, control the stirring speed to 150 rpm, extract for 60 min under strong stirring, cool to 10° C. (to reduce the emulsification ability of the emulsifier and the residual amount of the solvent), reduce the stirring speed by 20 rpm, and extract the free monomers;

[0275] 4. Centrifugal separation

[0276] The extracted emulsion is fed into a disc centrifuge at a speed of 10 L / min and a centrifuge 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 stripped, and water vapor is introduced at a steam pressure of 0.35 MPa and a vacuum degree of -0.095 MPa to remove the residual solvent to obtain residual monomers;

[0279] 6. Monomer recovery

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

[0281] Comparative Example 1

[0282] 1. Preprocessing

[0283] 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., vacuumized to -0.085 MPa, and flash distilled to remove unreacted low-boiling dienes, butadiene or isoprene;

[0284] 2. Extraction

[0285] Add 200 kg of hexane, control the stirring speed to 100 rpm, extract for 30 minutes under strong stirring, cool to 15°C (to reduce the emulsification ability of the emulsifier and the residual amount of solvent), reduce the stirring speed to 40 rpm, and extract the free monomer;

[0286] 3. Centrifugal separation

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

[0288] 4. Solvent recovery

[0289] Flash steam stripping, introducing water vapor with a steam pressure of 0.35 MPa and evacuating the vacuum degree to -0.085 MPa to remove the residual solvent and obtain the residual monomer;

[0290] 6. Monomer recovery

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

[0292] Comparative Example 2

[0293] 1. Preprocessing

[0294] 200 kg of diethyl itaconate-isoprene polymer emulsion after emulsion polymerization, wherein the rubber content is 35% and the residual amount of diethyl itaconate monomer is 3.6%, is added into a reaction kettle, 0.3 kg of sodium polysulfide and 0.6 kg of sodium dimethyldithiocarbamate are added, the temperature is raised to 40° C., vacuumized to -0.09 MPa, and flash distilled to remove unreacted low-boiling dienes, butadiene or isoprene;

[0295] 2. Extraction

[0296] Add 200 kg of hexane, control the stirring speed to 130 rpm, extract for 45 min under strong stirring, cool to 15 ° C (to reduce the emulsification ability of the emulsifier and the residual amount of solvent), reduce the stirring speed by 30 rpm, and extract the free monomer;

[0297] 3. Centrifugal separation

[0298] Enter the disc centrifuge at a speed of 15L / min and a centrifuge speed of 6000rpm. Under the action of centrifugation, the solvent with residual monomers is separated from the latex;

[0299] 4. Solvent recovery

[0300] Flash steam stripping, introducing water vapor with a steam pressure of 0.35 MPa and evacuating the vacuum degree to -0.085 MPa to remove the residual solvent and obtain the residual monomer;

[0301] 6. Monomer recovery

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

[0303] Comparative Example 3

[0304] 1. Preprocessing

[0305] 200 kg of the dimethyl fumarate-butadiene polymer emulsion after emulsion polymerization, with a rubber content of 40% and a residual dimethyl fumarate of 4.2%, is added to a reaction kettle, and 0.2 kg of sodium nitrite and 0.5 kg of sodium dimethyldithiocarbamate are added. The temperature is raised to 40° C., and the vacuum is drawn to -0.085 MPa, and flash evaporation is performed to remove unreacted low-boiling dienes, butadiene or isoprene;

[0306] 2. Extraction

[0307] Add the solvent, control the stirring speed to 100-200 rpm, extract for 20-90 min under strong stirring, cool to 10-25° C. (reduce the emulsification capacity of the emulsifier and the residual amount of the solvent), reduce the stirring speed by 20-100 rpm, and extract the free monomer;

[0308] 3. Centrifugal separation

[0309] Enter the disc centrifuge at a speed of 10 to 25 L / min, and the centrifuge speed is 4000 to 8000 rpm. Under the action of centrifugation, the solvent with residual monomers is separated from the latex;

[0310] 4. Solvent recovery

[0311] Flash steam stripping, introducing water vapor at a steam pressure of 0.25 to 0.45 MPa and evacuating the vacuum degree at -0.075 to -0.095 MPa to remove the residual solvent and obtain the residual monomer;

[0312] 6. Monomer recovery

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

[0314] Table 1 Extraction results of the embodiments and comparative examples

[0315] Extraction rate / % Residue in latex / % Recycling 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 Embodiment 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 Embodiment 14 94 0.74 22.37952 23.31 4.00 Embodiment 15 93 0.60 14.41872 15.81 8.80 Example 16 92 1.92 43.056 44.16 2.50

[0316] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0317] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A process for recovering high boiling point monomers in bio-based rubber latex, comprising the following steps: S1) mixing the bio-based rubber latex and the terminator and flash evaporating the mixture to obtain a pretreated bio-based rubber latex, wherein the bio-based rubber latex has a latex solid content of 1 to 75 wt %, and a high boiling point monomer residual content of 0.01 to 100 wt %; S2) mixing the pretreated bio-based rubber latex and agglomerating agent solution and then introducing steam; S3) extracting the emulsion obtained in step S2) with an extractant to obtain free monomers and an extracted emulsion; S4) centrifuging the extracted emulsion to obtain a solvent and latex containing residual monomers; S5) flash stripping the solvent containing the residual monomer to obtain the residual monomer; S5) separating and purifying the residual monomers and free monomers to obtain recovered monomers.

2. The recycling process according to claim 1, characterized in that: The bio-based rubber latex is 100 parts by weight, the terminator is 0.1 to 5 parts by weight, the agglomerating agent is 0.01 to 5 parts by weight, and the extractant is 20 to 1000 parts by weight.

3. The recycling process according to claim 1 or 2, characterized in that: The terminator is selected from one or more of sodium polysulfide, nitrite, hydroxylamine compounds and sodium dimethyldithiocarbamate; 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, oleyl amino oleate, carbamate, methyl carbamate, aminopropylamine dioleate, oleyl glycerol and polyetheramine with a molecular weight of less than 400; The extractant is selected from one or more of benzene, toluene, methyl chloride, dichloromethane, carbon disulfide, hexane, heptane, isooctane, xylene, cyclohexane, petroleum ether, pentane, ether and ethyl acetate.

4. The recycling process according to claim 1, characterized in that: In step S1), the flash evaporation temperature is 30-45°C, and the flash evaporation is evacuated to -0.065-0.095 MPa.

5. The recycling process according to claim 1, characterized in that: In step S2), the agglomerating agent solution is an agglomerating agent aqueous solution with a concentration of 0.1 to 5 wt%, the mixing temperature is 30 to 45° C., and the stirring is 0.5 to 4 h; the steam is water vapor or solvent vapor, the pressure is 0.05 to 0.45 MKPa, and the introduction time is 0.2 to 1.5 h.

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

7. The recycling process according to claim 1, characterized in that: In step S3), the extraction is specifically: Add an extractant to the emulsion obtained in step S2), stir at a stirring speed of 100-230 rpm for 20-90 min, cool to 10-25° C., and stir at a speed of 20-100 rpm.

8. The recycling process according to claim 1, characterized in that: In step S4), the feed rate of the centrifugal separation is 10-25 L / min, and the rotation speed is 4000-8000 rpm.

9. The recycling process according to claim 1, characterized in that: In step S5), the steam pressure of the flash steam stripping is 0.25 to 0.45 MPa, and the vacuum degree is -0.075 to -0.095 MPa.

10. The recycling process according to any one of claims 1 to 9, characterized in that: The bio-based rubber latex is selected from 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%, the residual amount of high boiling point monomer is 2-25wt%; the boiling point of the high boiling point monomer is greater than 200°C.