Method for separating bio-based itaconate rubber in emulsion

Abstract

The invention provides a method for separating bio-based itaconate rubber in an emulsion. According to the method, firstly, an agglomerating agent is added, so that the particle size of bio-based itaconate rubber latex particles with the original small particle size in the emulsion is increased, the stability of the emulsion is reduced, polymer separation is facilitated, meanwhile, an emulsifier attached to the surfaces of the latex particles can be released into a water phase, and the residual amount of the emulsifier in the polymer (namely the soap content of the product) is reduced. Compared with the traditional method, the method provided by the invention is suitable for large-scale production, the generation of waste liquid in the production process is greatly reduced, meanwhile, the residues of monomers and oligomers in the product can be effectively reduced, the product quality is improved, particularly, through the design of four functional areas of the double-screw extruder, the efficient pretreatment, compression, shearing and separation of the material are realized, and the product quality is improved. And the whole separation process is more efficient and stable.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of polymer separation, and particularly relates to a method for separating bio-based itaconate rubber in an emulsion. BACKGROUND

[0002] With the increasing emphasis on environmental protection and sustainable development, the research and application of bio-based materials have gradually become a hot topic. Among them, bio-based itaconate rubber, as a new type of environmentally friendly material, has shown broad application prospects in the rubber industry due to its excellent physical and mechanical properties and high bio-based content. At present, bio-based itaconate rubber is prepared by emulsion polymerization, and itaconate monomers are copolymerized with conjugated diene monomers to form high molecular materials with specific structure and properties.

[0003] CN119955016A discloses a bio-based itaconate rubber prepared by emulsion polymerization and a preparation method thereof. The method uses itaconate monomers and butadiene as raw materials to prepare bio-based itaconate rubber through free radical emulsion polymerization, and the monomer conversion rate can reach more than 85%. CN115124653B proposes a bio-based rubber preparation method, which uses low-temperature oxidation-reduction emulsion polymerization process for polymerization reaction, and then uses flocculants for demulsification and drying. The prepared rubber has suitable molecular weight and molecular weight distribution, and the monomer conversion rate can reach more than 96%. CN116217809B discloses a method for preparing bio-based rubber by adding conjugated diene monomers and emulsifiers multiple times, so that the conversion rate of itaconate monomers can reach more than 99%, and the prepared bio-based rubber has low structure gel content and good wear resistance.

[0004] At present, the emulsion polymer obtained by the above method usually needs to be post-treated. Traditional post-treatment methods mainly include coagulation method, spray drying method and freeze drying method, etc. However, the above post-treatment methods have a series of problems. First, the traditional coagulation method usually needs a large amount of coagulant and water, which produces a large amount of waste liquid and does not meet the environmental protection requirements. Second, the spray drying method and the freeze drying method have high energy consumption, large equipment investment and high production cost. Third, the existing post-treatment methods are usually intermittent operation, which has low efficiency and is difficult to realize continuous production. Fourth, the traditional post-treatment method is difficult to effectively remove the residual monomers and oligomers in the emulsion, resulting in high impurity content in the final product and affecting the product quality. Moreover, the bio-based itaconate rubber separated by the post-treatment method in the prior art has the problem of insufficient adaptability to bio-based itaconate rubber with special structure, which easily leads to the problem of performance decline or structure damage. SUMMARY

[0005] Therefore, the present application aims to provide a method for separating bio-based itaconate rubber in emulsion.

[0006] To achieve this goal, the present application adopts the following technical solutions:

[0007] The present application provides a method for separating bio-based itaconate rubber in emulsion, comprising the following steps:

[0008] S1: mixing bio-based itaconate rubber emulsion with an aqueous solution of agglomeration agent, a solution of pH regulator, degassing, and obtaining large-particle-size bio-based itaconate rubber emulsion;

[0009] S2: mixing large-particle-size bio-based itaconate rubber emulsion with organic solvent, extraction, adding the extracted emulsion into a twin-screw extruder, solid-liquid separation, and obtaining bio-based itaconate rubber.

[0010] Preferably, the solid content of the bio-based itaconate rubber emulsion is 20-60%.

[0011] Preferably, the agglomeration agent in the aqueous solution of agglomeration agent is selected from any one or more of potassium chloride, potassium sulfate, magnesium chloride, magnesium sulfate, or calcium chloride.

[0012] Preferably, the mass fraction of the aqueous solution of agglomeration agent is 0.1-0.5%, preferably 0.2-3%.

[0013] Preferably, the fraction of the agglomeration agent is 0.1-0.5 parts based on 100 parts of bio-based itaconate rubber in bio-based itaconate rubber emulsion.

[0014] Preferably, the pH regulator in the solution of pH regulator is selected from any one or more of oxalic acid, acetic acid, propionic acid, hydrochloric acid, carbonic acid, phosphoric acid, hydroxyacetic acid, ethylenediaminetetraacetic acid, or sulfamic acid.

[0015] Preferably, the mass fraction of the solution of pH regulator is 1-20%, preferably 3-15%.

[0016] Preferably, the fraction of the pH regulator is 0.05-0.2 parts based on 100 parts of bio-based itaconate rubber in bio-based itaconate rubber emulsion.

[0017] Preferably, the parameters for emulsion devolatilization are: temperature 5-70℃, pressure -0.1-0 MPa, time 5-40 min; preferably: temperature 10-40℃, pressure -0.09--0.04 MPa, time 10-30 min.

[0018] Preferably, the organic solvent is selected from any one or more of toluene, xylene, DMF, n-hexane, cyclohexane or ethyl acetate.

[0019] Preferably, the fraction of the organic solvent is 100-200 parts, based on 100 parts of the bio-based itaconate rubber in the bio-based itaconate rubber emulsion.

[0020] Preferably, the mixing in step S2 further comprises an auxiliary agent.

[0021] Preferably, the auxiliary agent is selected from any one or more of an antioxidant, an antifoaming agent, a UV stabilizer, an antistatic agent, a reinforcing agent or a flame retardant.

[0022] Preferably, the mixing in step S2 is performed under stirring, and the stirring time is 5-20 min.

[0023] Compared with the prior art, the present application has the following advantages:

[0024] The present application provides a method for separating bio-based itaconate rubber in an emulsion. First, an agglomerating agent is added to increase the particle size of the bio-based itaconate rubber latex particles in the emulsion, reduce the stability of the emulsion, facilitate the separation of the polymer, and release the emulsifier attached to the surface of the latex particles into the water phase, thereby reducing the residual amount of emulsifier in the polymer (i.e., the soap content of the product). Subsequently, the large-particle-size bio-based itaconate rubber emulsion is extracted to separate the residual monomers and oligomers from the polymer emulsion. Finally, the extracted emulsion is fed into a twin-screw extruder for demulsification and purification, thereby realizing an efficient, continuous and environmentally friendly solid-liquid separation process of the polymer emulsion. Compared with the traditional method, the method provided by the present application is suitable for large-scale production, greatly reduces the generation of waste liquid during production, and effectively reduces the residual amount of monomers and oligomers in the product, thereby improving the product quality. In particular, through the design of the four functional zones of the twin-screw extruder, efficient pretreatment, compression, shearing and separation of the material are realized, making the entire separation process more efficient and stable. In addition, the present application can further optimize the separation effect and improve the quality of the bio-based itaconate rubber by reasonably controlling the devolatilization parameters and selecting appropriate agglomerating agents, pH adjusters and organic solvents. DETAILED DESCRIPTION

[0025] The technical solutions of the present application will be described clearly and completely below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0026] In view of the problems that the existing technology may have low efficiency, be discontinuous and not environmentally friendly, and may generate a large amount of waste liquid and have high residual monomer and oligomer in the product, affecting the product quality, the present application provides a method for separating bio-based itaconate rubber in an emulsion, comprising the following steps:

[0027] S1: mixing the bio-based itaconate rubber emulsion with an aqueous solution of an agglomerating agent and a pH adjusting agent solution, degassing, and obtaining a large-particle-size bio-based itaconate rubber emulsion;

[0028] S2: mixing the large-particle-size bio-based itaconate rubber emulsion with an organic solvent, extracting, adding the extracted emulsion into a twin-screw extruder, and solid-liquid separation, to obtain bio-based itaconate rubber.

[0029] In the present application, the bio-based itaconate rubber emulsion is first mixed with an aqueous solution of an agglomerating agent and a pH adjusting agent solution, and degassed to obtain a large-particle-size bio-based itaconate rubber emulsion.

[0030] As a preferred embodiment, the present application first performs emulsion devolatilization treatment on the bio-based itaconate rubber emulsion, and then mixes it with an aqueous solution of an agglomerating agent and a pH adjusting agent solution. In the emulsion devolatilization treatment, the bio-based itaconate rubber emulsion is preferably pumped into a degassing kettle, and direct steam stripping is used to remove residual conjugated diene monomers, with the control parameters being: temperature 5-70°C, preferably 10-40°C; pressure -0.1-0 MPa, preferably -0.09--0.04 MPa; and time 5-40 min, preferably 10-30 min.

[0031] The bio-based itaconate rubber emulsion includes a copolymer of conjugated diene monomer units and itaconate monomer units (i.e., bio-based itaconate rubber) and other components. In the present application, the itaconate monomer units are selected from any one or more of dimethyl itaconate, diethyl itaconate, di-n-propyl itaconate, di-n-butyl itaconate, diisopropyl itaconate, diisobutyl itaconate, di-n-pentyl itaconate, diisopentyl itaconate, dihexyl itaconate, diheptyl itaconate, dioctyl itaconate, dinonyl itaconate, or didecyl itaconate; the conjugated diene is isoprene and / or 1,3-butadiene; and the molar ratio of itaconate monomer to conjugated diene monomer is 1:(1-4.5), such as 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, or 1:4.5, etc.

[0032] In the present application, the solid content in the bio-based itaconate rubber emulsion is 20-60%, such as 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, or 60%, etc.

[0033] In the present application, after the devolatilization of the emulsion is finished, the obtained emulsion is preferably mixed with an aqueous solution of agglomerating agent and a solution of pH adjusting agent.

[0034] In the present application, the agglomerating agent in the aqueous solution of agglomerating agent is selected from any one or more of potassium chloride, potassium sulfate, magnesium chloride, magnesium sulfate or calcium chloride, preferably any one or more of potassium chloride, magnesium chloride or calcium chloride; and the mass fraction of the aqueous solution of agglomerating agent is 0.1% to 5%, such as 0.1%, 0.5%, 1%, 2%, 3%, 4% or 5%, etc.

[0035] In some embodiments of the present application, the fraction of the agglomerating agent is 0.1 to 0.5 parts, such as 0.1 part, 0.15 part, 0.2 part, 0.25 part, 0.3 part, 0.35 part, 0.4 part, 0.45 part or 0.5 part, etc., based on 100 parts of the bio-based itaconate rubber in the bio-based itaconate rubber emulsion.

[0036] In the present application, the addition of the above-mentioned agglomerating agent can make the particle size of the bio-based itaconate rubber latex particles originally smaller in the emulsion larger, reduce the stability of the emulsion, facilitate the separation of the polymer, and at the same time release the emulsifier attached to the surface of the latex particles into the aqueous phase, reducing the residual amount of emulsifier in the polymer (i.e., the soap content of the product).

[0037] It should be noted that the agglomerating agent in the present application is different from the flocculating agent. The agglomerating agent needs to neutralize the surface charge of the smaller particle size latex particles, destroy the balance state of the smaller particle size latex particles, make them agglomerate into larger latex particles, and then reach a new balance state, i.e., the polymer is still dispersed in the emulsion in the form of latex particles after agglomeration, the difference is that the particle size of the latex particles is increased. The flocculating agent completely destroys the balance state of the latex particles, making them precipitate and coagulate into blocks.

[0038] In the present application, the pH adjusting agent in the solution of pH adjusting agent is selected from any one or more of oxalic acid, acetic acid, propionic acid, hydrochloric acid, carbonic acid, phosphoric acid, glycolic acid, ethylenediaminetetraacetic acid or sulfamic acid, preferably any one or more of oxalic acid, hydrochloric acid, glycolic acid and ethylenediaminetetraacetic acid. The mass fraction of the solution of pH adjusting agent is 1% to 20%, such as 1%, 3%, 5%, 8%, 10%, 13%, 15%, 18% or 20%, etc.

[0039] In some embodiments of the present application, the fraction of the pH adjusting agent is 0.05 to 0.2 parts, such as 0.05 part, 0.08 part, 0.1 part, 0.13 part, 0.15 part, 0.18 part or 0.2 part, etc., based on 100 parts of the bio-based itaconate rubber in the bio-based itaconate rubber emulsion.

[0040] In the present application, the addition of the above-mentioned pH regulator is used to reduce the pH value of the system, change the surface charge distribution of the latex particles, affect the agglomeration behavior, promote dispersion and stability; at the same time, it reduces the polarity of the surface of the latex particles, reduces the van der Waals force by adsorbing on the particle surface, and prevents flocculation.

[0041] Then, according to the present application, the large particle size bio-based itaconate rubber emulsion is mixed with an organic solvent for extraction. The organic solvent is used to effectively dissolve the residual monomers and oligomers (referring to the dimers, trimers and polymers of conjugated diene monomers) in the emulsion.

[0042] The organic solvent is selected from any one or more of toluene, xylene, DMF, n-hexane, cyclohexane or ethyl acetate, preferably any one or more of n-hexane, cyclohexane or ethyl acetate, and more preferably cyclohexane.

[0043] In some embodiments of the present application, the amount of the organic solvent is 100-200 parts, such as 100 parts, 110 parts, 120 parts, 130 parts, 140 parts, 150 parts, 160 parts, 170 parts, 180 parts, 190 parts or 200 parts, etc., based on 100 parts of the bio-based itaconate rubber in the bio-based itaconate rubber emulsion.

[0044] As a preferred embodiment, the large particle size bio-based itaconate rubber emulsion is mixed with an organic solvent and an auxiliary agent. The auxiliary agent is used to improve the stability and performance of the final product.

[0045] In the present application, the auxiliary agent is selected from any one or more of antioxidants, antifoaming agents, UV stabilizers, antistatic agents, reinforcing agents or flame retardants.

[0046] In the present application, the mixing in step S2 is preferably carried out under stirring, and the stirring time is 5-20 min, such as 5 min, 10 min, 15 min or 20 min, etc.

[0047] Finally, according to the present application, the bio-based itaconate rubber emulsion after extraction is sent into a twin-screw extruder for solid-liquid separation.

[0048] In some embodiments of the present application, the process flow of the twin-screw extruder is as follows:

[0049] The bio-based itaconate rubber emulsion after extraction is fed into a feed pump→ a co-rotating twin-screw extruder 1→ a counter-rotating twin-screw pump→ a co-rotating twin-screw extruder 2→ a discharge port.

[0050] The length-diameter ratio of the counter-rotating twin-screw pump is 10-20, such as 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20, preferably 12-18, and more preferably 16, so that the pressure and structural strength are more suitable, and the water-containing rubber can be efficiently, stably and non-pulsatingly conveyed.

[0051] The process parameters of the co-rotating twin-screw extruder 1 are as follows: the first-stage temperature is 50-75℃, and the first-stage absolute pressure is 10-20 kPa; the second-stage temperature is 70-85℃, and the second-stage absolute pressure is 8-15 kPa.

[0052] The first-stage temperature is 50-75℃, which can be 50℃, 55℃, 60℃, 65℃ or 75℃, and the first-stage absolute pressure is 10-20 kPa, which can be 10 kPa, 12 kPa, 15 kPa, 18 kPa or 20 kPa.

[0053] The second-stage temperature is 70-85℃, which can be 70℃, 72℃, 75℃, 78℃, 80℃ or 85℃, and the second-stage absolute pressure is 8-15 kPa, which can be 8 kPa, 9 kPa, 10 kPa, 11 kPa, 12 kPa, 13 kPa, 14 kPa or 15 kPa.

[0054] The process parameters of the co-rotating twin-screw extruder 2 are as follows: the first-stage temperature is 105-120℃, and the first-stage absolute pressure is 4-10 kPa; the second-stage temperature is 105-120℃, and the second-stage absolute pressure is 3-6 kPa.

[0055] The first-stage temperature is 105-120℃, which can be 105℃, 108℃, 110℃, 112℃, 115℃, 118℃ or 120℃, and the first-stage absolute pressure is 4-10 kPa, which can be 4 kPa, 5 kPa, 6 kPa, 7 kPa, 8 kPa, 9 kPa or 10 kPa.

[0056] The second-stage temperature is 105-120℃, which can be 105℃, 108℃, 110℃, 112℃, 115℃, 118℃ or 120℃, and the second-stage absolute pressure can be 3 kPa, 4 kPa, 5 kPa or 6 kPa.

[0057] The co-rotating twin-screw extruder 1 can remove water, and the co-rotating twin-screw extruder 2 can remove high-boiling substances, such as some oligomers. Moreover, the separation efficiency can be significantly improved by the first stage and the second stage.

[0058] The length-diameter ratio of the double screw extruder is 50-60, such as 50, 51, 52, 53, 54, 55, 56, 57, 58, 59 or 60, preferably 52-58, and more preferably 56, so that the double screw extruder has better shearing and separating effects.

[0059] Compared with the combination of two counter-rotating double screw extruders or the combination of a homo-rotating double screw extruder and a counter-rotating double screw extruder, the combination of the two homo-rotating double screw extruders has more excellent shearing and separating effects, can destroy the stability of the bio-based itaconate emulsion, and separate the polymer from the emulsion. Compared with the traditional chemical flocculation method, the homo-rotating double screw extruder has excellent self-cleaning performance, reduces the use of a large amount of coagulant and cleaning water, and avoids the generation of a large amount of waste liquid; at the same time, the residual monomers and dimers in the emulsion can be effectively removed at a lower operating temperature, the product quality is not affected by the residual impurities, and the product structure is not damaged at the operating temperature (≤120°C) and the performance is not reduced.

[0060] In some preferred embodiments of the present application, the method comprises the following steps:

[0061] Based on the total amount of bio-based itaconate rubber in the emulsion being 100 parts:

[0062] (1) Emulsion devolatilization: The bio-based itaconate rubber emulsion is punched into a degassing kettle, and direct steam stripping is used to remove residual conjugated diene monomers;

[0063] (2) Agglomeration: 0.1-0.5 parts of an agglomeration agent aqueous solution and 0.05-0.2 parts of a pH regulator solution are added, and the degassing is continued for ≥30 minutes to obtain a large-particle-size bio-based itaconate rubber emulsion;

[0064] (3) Extraction: 100-200 parts of an organic solvent and an additive are added and stirred for 5-20 minutes;

[0065] (4) Double screw extruder solid-liquid separation: the emulsion pretreated in the foregoing is added into a double screw extruder, and solid-liquid separation is performed to obtain bio-based itaconate rubber raw rubber.

[0066] In order to further illustrate the present application, the following examples are used for detailed description. The experimental raw materials used in the following examples of the present application are all commercially available.

[0067] Preparation Example 1

[0068] The present preparation example provides a bio-based itaconate rubber emulsion, and the method is as follows:

[0069] In a polymerization device, water-soluble components: 870 g of deionized water, 12 g of emulsifier fatty acid sodium / diffused rosin acid potassium complex emulsifier, 1.2 g of electrolyte potassium chloride, 0.26 g of activator ferrous sulfate-ethylenediaminetetraacetic acid disodium salt, 0.20 g of formaldehyde sodium hydrogensulfite, and 0.09 g of oxygen scavenger sodium hydrosulfite, and oil-soluble components: 176 g of diethyl itaconate, 0.29 g of molecular weight regulator n-dodecyl mercaptan, and 114 g of conjugated diene butadiene were mixed, and then the polymerization device was closed; vacuum was drawn and then nitrogen was filled, and the operation was performed 2-5 times; 0.23 g of initiator p-menthane hydroperoxide was added to the polymerization device, and the reaction was performed at 3-20°C and under a pressure of 0.1-2 MPa, and after 10 h, 1.5 g of terminator isopropyl hydroxylamine was added to terminate the reaction, and finally a bio-based rubber emulsion was obtained.

[0070] In the following examples, the mass of the bio-based itaconate rubber in the bio-based itaconate rubber emulsion is 100 parts.

[0071] Example 1

[0072] In this example, a method for separating polymers in an emulsion is provided, in particular for separating polymers in a bio-based itaconate rubber emulsion. The method comprises the following steps:

[0073] (1) Emulsion devolatilization: The bio-based itaconate rubber emulsion is pumped into a degassing kettle, and direct steam stripping is used to remove residual conjugated diene monomers. The bio-based itaconate rubber emulsion comprises a copolymer of conjugated diene monomer units and itaconate monomer units, wherein the itaconate monomer is diethyl itaconate, the conjugated diene is butadiene, the molar ratio of diethyl itaconate to butadiene is 1:3, and the emulsion solid content is 35%.

[0074] (2) Agglomeration: 0.45 parts of potassium chloride aqueous solution (mass fraction of 3%) is added to the devolatilized emulsion as an agglomeration agent, and 0.18 parts of oxalic acid solution (mass fraction of 10%) is added as a pH adjuster, and the temperature in the degassing kettle is 20°C and the pressure is -0.06 MPa, and the degassing time is 40 min, and a large particle size bio-based itaconate rubber emulsion is obtained. During the agglomeration process, potassium chloride can effectively promote the aggregation of polymer particles in the emulsion to form larger particles, which is convenient for subsequent separation.

[0075] (3) Extraction: 180 parts of cyclohexane as an organic solvent and 0.01 parts of an additive mixture (antioxidant 3530T: defoamer DF-163: UV stabilizer UV-531 = 5:2:3, mass ratio) are added to the agglomerated emulsion, and stirring is performed for 15 minutes. During the extraction process, cyclohexane can effectively dissolve the residual monomers and oligomers in the emulsion, and the additive can improve the stability and performance of the final product.

[0076] (4) Solid-liquid separation by a twin-screw extruder: the emulsion subjected to the foregoing pretreatment is added to a twin-screw extruder for solid-liquid separation to obtain bio-based itaconate rubber crumb;

[0077] The process of the twin-screw extruder is as follows: emulsion through a feeding pump → a co-rotating twin-screw extruder 1 → a counter-rotating twin-screw pump → a co-rotating twin-screw extruder 2 → a discharge port, and the specific process is as follows:

[0078] S1: Twin-screw extruder temperature rising: the co-rotating twin-screw extruder 1 and the co-rotating twin-screw extruder 2 are respectively raised in temperature, and the specific parameters are as follows: the first section of the co-rotating twin-screw extruder 1 is raised in temperature to 50-70℃, and the second section is raised in temperature to 70-85℃; the first section and the second section of the co-rotating twin-screw extruder 2 are both raised in temperature to 105-120℃; in this embodiment, the first section of the co-rotating twin-screw extruder 1 is raised in temperature to 60℃, and the second section is raised in temperature to 75℃; the first section of the co-rotating twin-screw extruder 2 is raised in temperature to 110℃, and the second section is raised in temperature to 105℃.

[0079] S2: Emulsion feeding, and negative pressure extraction of the first chamber of the twin-screw extruder 1: the negative pressure pipeline of the co-rotating twin-screw extruder 1 is opened, and the negative pressure in the first chamber of the co-rotating twin-screw extruder 1 is controlled to be about 15 KPa, and a large amount of air bubbles (liquid water changes into gaseous water vapor) appear in the emulsion;

[0080] S3: Negative pressure extraction of the second chamber of the twin-screw extruder 1: the negative pressure pipeline of the co-rotating twin-screw extruder 1 is opened, and the negative pressure in the second chamber of the co-rotating twin-screw extruder 1 is controlled to be about 10 KPa; after the co-rotating twin-screw extruder 1 discharges, the material (the emulsion has been completely demulsified, and the water content is 5%-15%) is transported to the co-rotating twin-screw extruder 2 through the counter-rotating twin-screw pump;

[0081] S4: Feeding of the co-rotating twin-screw extruder 2: the two chambers of the co-rotating twin-screw extruder 2 are extracted at a negative pressure of about 10 KPa;

[0082] The parameters of the co-rotating twin-screw extruder 1, the co-rotating twin-screw extruder 2 and the counter-rotating twin-screw pump are shown in Table 1:

[0083] Table 1

[0084] Apparatus name Model Screw diameter (mm) Screw rotation speed (r / min) Screw length-diameter ratio Power (KW) Counter-rotating twin screw pump SLB-35 / 45-1.5-16 35 45 16 1.5 Co-rotating twin screw extruder 1 / 2 TSD-36 / 300-11-56 38.2 / 35.6 300 56 11

[0085] Example 2

[0086] In this embodiment, the bio-based itaconate rubber emulsion solid content is 40%, in which the itaconate monomer is selected by dibutyl itaconate, the conjugated diene is butadiene, and the molar ratio of dibutyl itaconate to butadiene is 1:3. The method comprises the following steps:

[0087] (1) Emulsion devolatilization: the bio-based itaconate rubber emulsion is pumped into the degassing kettle, and the direct steam stripping method is used to remove the residual conjugated diene monomer.

[0088] (2) Agglomeration: 0.2 parts of a mixture of magnesium chloride and potassium chloride 1:1 (mass ratio) aqueous solution (mass fraction of 2.5%) and 0.1 parts of hydrochloric acid solution (mass fraction of 5%) as pH regulator are added to the devolatilized emulsion, and the temperature is 500℃, the pressure is-0.04 MPa, and the degassing time is 30 min, to obtain a large particle size bio-based itaconate rubber emulsion. In the agglomeration process, magnesium chloride and potassium chloride can effectively promote the aggregation of polymer particles in the emulsion to form larger particles, which is convenient for subsequent separation.

[0089] (3) Extraction: 120 parts of cyclohexane are added to the agglomerated emulsion as an organic solvent, and 0.01 parts of an additive mixture (antioxidant 3530T: defoamer DF-163: UV stabilizer UV-531 = 5:2:3, mass ratio) are added, and stirred for 15 minutes. In the extraction process, cyclohexane can effectively dissolve the residual monomers and oligomers in the emulsion, and the additives can improve the stability and performance of the final product.

[0090] (4) Solid-liquid separation by twin-screw extruder: the emulsion pretreated by the foregoing is added to the twin-screw extruder for solid-liquid separation to obtain bio-based itaconate rubber raw rubber.

[0091] Example 3

[0092] In this embodiment, the bio-based itaconate rubber emulsion solid content is 50%, in which the itaconate monomer is selected by diethyl itaconate, the conjugated diene is isoprene, and the molar ratio of diethyl itaconate to isoprene is 1:3. The method comprises the following steps:

[0093] (1) Emulsion devolatilization: the bio-based itaconate rubber emulsion is pumped into the degassing kettle, and the direct steam stripping method is used to remove the residual conjugated diene monomer.

[0094] (2) Agglomeration: 0.3 parts of a mixture of magnesium chloride and potassium chloride 1:1 (mass ratio) aqueous solution (mass fraction of 2.5%) was added to the emulsion after devolatilization, and 0.15 parts of glycolic acid solution (mass fraction of 15%) was added as a pH regulator. The temperature in the degassing kettle was 15°C, the pressure was -0.09 MPa, and the degassing time was 35 min. A large particle size bio-based itaconate rubber emulsion was obtained. During the agglomeration process, magnesium chloride and potassium chloride can effectively promote the aggregation of polymer particles in the emulsion to form larger particles, facilitating subsequent separation.

[0095] (3) Extraction: 100 parts of DMF were added to the agglomerated emulsion as an organic solvent, and 0.01 parts of an additive mixture (antioxidant 1010: defoamer DF-163: UV stabilizer UV-531 = 5:2:3, mass ratio) was added, and stirred for 15 minutes. During the extraction process, cyclohexane can effectively dissolve the residual monomers and oligomers in the emulsion, and the additives can improve the stability and performance of the final product.

[0096] (4) Solid-liquid separation by twin-screw extruder: The emulsion prepared by the foregoing pretreatment was added to a twin-screw extruder for solid-liquid separation, and a bio-based itaconate rubber raw rubber was obtained.

[0097] The bio-based itaconate rubber raw rubber prepared by the above method has significantly reduced impurity content, moisture content, and oligomer residual amount, with ash content below 0.3%. Compared with the traditional coagulation method, the separation efficiency is improved by more than 30%, the energy consumption is reduced by about 25%, the product quality is more stable, and the environmental friendliness is significantly improved.

[0098] Comparative Example 1

[0099] Latex flocculation: 1 kg of deionized water was taken, 3 g of calcium chloride was added, the temperature was raised to 60°C, and the stirring paddle was stirred at a speed of 800 rpm. The bio-based itaconate rubber emulsion after removing butadiene under reduced pressure was slowly added to the calcium chloride solution, and 1% dilute sulfuric acid solution was added dropwise to make the pH value of the system 6.5-7.5. The bio-based itaconate rubber precipitated out.

[0100] Washing and drying: The flocculated bio-based itaconate rubber was washed with 1 kg of deionized water for 2 times, squeezed to remove water, and dried at 110°C for 2 h.

[0101] Comparative Example 2

[0102] Laboratory flocculation method:

[0103] The bio-based itaconate rubber was obtained by removing butadiene under reduced pressure, demulsifying with 500 g of ethanol, and drying in a vacuum oven to constant weight.

[0104] Performance test

[0105] The bio-based itaconate rubber raw rubber obtained from each example and comparative example was tested according to the following test methods, and the test methods were as follows:

[0106] (1) Itaconate monomer residual amount, conjugated diene residual amount, and oligomer residual amount test: tested by gas chromatography;

[0107] (2) Water content test: tested according to GB / T 37191-2018 Rubber, Crude Rubber Determination of Moisture Content Karl Fischer Method;

[0108] (3) Soap content test: tested according to GB / T 8657-2014 Styrene-butadiene crude rubber Determination of soap and organic acid content;

[0109] (4) Ash content test: tested according to GBT4498.1-2013 Rubber, Determination of ash content Part 1: Muffle method.

[0110] The test results are shown in Table 2:

[0111] Table 2

[0112] Itaconate ester monomer residual amount / ppm Conjugated diene residual amount / ppm Oligomer residual amount / ppm Water content / % Soap content / % Ash content / % Example 1 64 18 21 0.43 1.78 0.19 Example 2 72 15 20 0.36 1.56 0.23 Example 3 59 20 29 0.29 1.82 0.21 Comparative Example 1 95 18 85 0.41 3.32 0.62 Comparative Example 2 101 17 69 0.35 2.16 0.47

[0113] As can be seen from Table 1, the itaconate monomer residual amount and the oligomer residual amount in the products of the three groups of examples are significantly lower than those in the products of the two groups of comparative examples, indicating that the extraction and twin-screw separation techniques in the method can effectively reduce the residual monomers and oligomers in the products; and the soap content and ash content in the products of the examples are far lower than those in the products of the two groups of comparative examples, indicating that the techniques of agglomeration, pH adjustment, and twin-screw separation in the method can significantly reduce the residual emulsifiers in the products.

[0114] The above description of disclosed examples enables one of ordinary skill in the art to make or use the application. Various modifications to these examples will be readily apparent to those of ordinary skill in the art, and the generic principles defined herein can be applied to other examples without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the examples shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for separating bio-based itaconic acid ester rubber from an emulsion, characterized in that, Includes the following steps: S1: Mix the bio-based itaconic acid rubber latex with an aqueous agglomerating agent and a pH adjusting agent solution, and degas to obtain a large-particle-size bio-based itaconic acid rubber latex. S2: Mix the large-particle-size bio-based itaconic acid ester rubber emulsion with an organic solvent, extract it, add the extracted emulsion to a twin-screw extruder, and separate the solid and liquid to obtain bio-based itaconic acid ester rubber.

2. The method according to claim 1, characterized in that, The solid content of the bio-based itaconic acid ester rubber latex is 20-60%.

3. The method according to claim 1 or 2, characterized in that, The agglomerating agent in the aqueous solution is selected from any one or more of potassium chloride, potassium sulfate, magnesium chloride, magnesium sulfate, or calcium chloride. The mass fraction of the agglomerating agent aqueous solution is 0.1%~5%; Based on 100 parts of bio-based itaconic acid ester rubber in the bio-based itaconic acid ester rubber emulsion, the agglomerating agent comprises 0.1 to 0.5 parts.

4. The method according to any one of claims 1 to 3, characterized in that, The pH adjuster in the pH adjuster solution is selected from any one or more of oxalic acid, acetic acid, propionic acid, hydrochloric acid, carbonic acid, phosphoric acid, glycolic acid, ethylenediaminetetraacetic acid, or aminosulfonic acid; The pH adjuster solution has a mass fraction of 1% to 20%; Based on 100 parts of bio-based itaconic acid ester rubber in the bio-based itaconic acid ester rubber emulsion, the pH adjuster comprises 0.05 to 0.2 parts.

5. The method according to any one of claims 1 to 4, characterized in that, The parameters for emulsion devolatilization are: temperature 5~70℃, pressure -0.1~0 MPa, and time 5~40 min.

6. The method according to any one of claims 1 to 5, characterized in that, The organic solvent is selected from any one or more of toluene, xylene, DMF, n-hexane, cyclohexane, or ethyl acetate.

7. The method according to claim 6, characterized in that, Based on 100 parts of bio-based itaconic acid ester rubber in the bio-based itaconic acid ester rubber emulsion, the organic solvent comprises 100 to 200 parts.

8. The method according to any one of claims 1 to 7, characterized in that, The mixing in step S2 also includes additives.

9. The method according to claim 8, characterized in that, The additives are selected from any one or more of antioxidants, defoamers, UV stabilizers, antistatic agents, reinforcing agents, or flame retardants.

10. The method according to any one of claims 1 to 9, characterized in that, The mixing in step S2 is carried out under stirring conditions, and the stirring time is 5 to 20 minutes.