A method for removing surfactant from EVA emulsion

Abstract

The invention discloses a method for removing surfactant from EVA emulsion, comprising the following steps: adding demulsifier to EVA emulsion in polymerization section, filtering to obtain EVA solid after demulsification, adding EVA solid to solvent to obtain EVA solution, respectively introducing extractant and EVA solution from the top and bottom of extraction tower, mixing and stirring, making the surfactant in EVA solution enter extraction phase, the EVA solution from which surfactant is removed enters water separation section at the top of tower, realizing oil-water separation, the separated oil phase EVA solution flows out from the top pipeline of tower, enters devolatilization section, and obtains high-purity EVA elastomer or EVA resin through devolatilization process. The method is green and efficient, with simple operation process, not only can efficiently remove surfactant, but also can greatly improve production efficiency, improve product quality of EVA elastomer and EVA resin, and reduce production cost.

Description

Technical Field

[0001] The invention relates to the technical field of emulsion polymerization, and in particular to a method for removing a surfactant from an EVA emulsion. Background Art

[0002] Ethylene-vinyl acetate copolymer (EVA) is an important commercial polymer, and its performance is closely related to the content of vinyl acetate (VA) monomer units in the polymer chain (referred to as "VA content"). In practical applications, EVA is mainly divided into three types according to the VA content: (1) EVA emulsion, the VA content in EVA emulsion is 70wt%-95wt%, the number average molecular weight ranges from 20kg / mol to 240kg / mol, it has good acid and alkali resistance, UV aging resistance and good compatibility, and is widely used in adhesives, coatings, cement modifiers and other fields; (2) EVA elastomer, the VA content in EVA elastomer is 40wt%-70wt%, the number average molecular weight ranges from 30kg / mol to 200kg / mol, it has good wear resistance and electrical insulation, and is widely used in the cable industry and automotive industry parts and other fields; (3) EVA resin, the VA content in EVA resin is 5wt%-40wt%, the number average molecular weight ranges from 30kg / mol to 160kg / mol, it has good chemical stability, corrosion resistance and non-toxicity, and is widely used in photovoltaic module packaging, medical catheters and antibacterial materials and other fields.

[0003] The VA content in EVA emulsion and EVA elastomer is higher than 40wt%. They are usually synthesized by emulsion polymerization at low temperature and low pressure of 35℃-80℃ and less than 5MPa. The production process is safe and environmentally friendly. The production process of EVA resin is mainly high-pressure bulk polymerization and emulsion polymerization. According to the different reactors used, the high-pressure bulk polymerization method is divided into tubular method and kettle method. The advantage of the tubular method is that it can be mass-produced and the VA content in the synthesized EVA resin is low (generally less than 30wt%); the advantage of the kettle method is that the reaction temperature and pressure are uniform. The high-pressure bulk polymerization process is mature and has a high degree of continuity, but it still faces some problems, such as difficulty in removing reaction heat and harsh production conditions (over 250℃, 200MPa). In addition, the obvious disadvantage of the EVA resin obtained by the high-pressure bulk method is the high degree of branching. The large number of branched chains in the molecular structure affect the comprehensive performance of the EVA resin. The emulsion polymerization method has mild conditions, and EVA resins with high ethylene content and high molecular weight can be synthesized under the conditions of 35℃-80℃ and 0MPa-10MPa (gauge pressure). Obviously, EVA emulsion, EVA elastomer and EVA resin can be synthesized under very mild conditions by using the emulsion polymerization process. However, emulsion polymerization requires the addition of surfactants. After polymerization, the surfactants will enter the polymer, resulting in the deterioration of the physical properties such as electrical properties, optical properties and water resistance of the EVA polymer used as an elastomer and resin. Therefore, it is necessary to remove the surfactants from the EVA elastomer and EVA resin to obtain pure EVA elastomer or resin.

[0004] A survey of relevant literature found that Mobarakeh et al. (Mobarakeh HS, Daronkola MR R. Effect of different parameters in emulsion copolymerization of vinyl acetate-ethylene in 7.5 liter high pressure reactor. Iranian Polymer Journal, 2005, 14 (6): 579-587.) reported a method for removing the surfactant sodium dodecyl sulfate from EVA obtained by emulsion copolymerization of ethylene and vinyl acetate. The method comprises drying the EVA emulsion at 40° C. under vacuum conditions for 24 h, dissolving the obtained dry sample in tetrahydrofuran to obtain a tetrahydrofuran solution of EVA, adding deionized water to the tetrahydrofuran solution of EVA to precipitate EVA, collecting the EVA filter cake after filtration, and rinsing it with deionized water for multiple times to remove the surfactant. Ovando-Medina et al. (Ovando-Medina VM, Díaz-Flores PE, Peralta RD, Mendizábal E, Cortez-Mazatan G Y. Semicontinuous heterophase copolymerization of vinyl acetate and butyl acrylate. Journal of Applied Polymer Science, 2013, 127(4): 2458-2464.) reported a method for removing mixed surfactants sodium dodecyl sulfate and poly(ethylene oxide) dodecyl ether from copolymers of vinyl acetate and butyl acrylate. First, the polymer emulsion was freeze-dried to obtain a dry sample, and then the solid sample was rinsed with hot water several times to remove the surfactant.

[0005] The surfactant removal method reported in the above literature has a certain effect, but it is not possible to completely remove the surfactant in the product, and the residual surfactant content is generally 10wt%-20wt%. The reason is that when washing the polymer with water, the surfactant is wrapped in EVA, and only the free surfactant on the outer surface of the EVA particles can be washed away, while the surfactant wrapped inside the EVA particles still remains in the EVA. Therefore, the surfactant wrapped in the polymer cannot be completely removed by simple water washing or alcohol washing. Summary of the invention

[0006] The invention aims to provide a method for removing a surfactant in an EVA emulsion. The method is green and efficient, has a simple operation process, can effectively remove the surfactant, and can greatly improve production efficiency, improve the product quality of an EVA elastomer and an EVA resin, and reduce production costs.

[0007] To achieve the above object, the present invention provides a method for removing a surfactant from an EVA emulsion, which specifically comprises the following steps:

[0008] S1, adding a demulsifier to the EVA emulsion from the polymerization section, the EVA micelles after demulsification aggregate into particles, and filtering to obtain EVA solid;

[0009] S2, adding the EVA solid obtained in step S1 into a solvent, stirring and dissolving at a certain temperature to obtain an EVA solution;

[0010] S3, introducing the extractant from the top of the extraction tower at a certain flow rate, opening the extraction tower for stirring, and simultaneously introducing temperature-controlled water into the jacket of the extraction tower to raise the temperature inside the extraction tower to a certain level;

[0011] S4, introducing the EVA solution obtained in step S2 from the bottom of the extraction tower at a certain flow rate;

[0012] S5, stirring the solution obtained by mixing the extractant in step S3 with the EVA solution in step S4, so that the surfactant in the EVA solution enters the extraction phase;

[0013] S6, the surfactant-containing extract phase in step S5 enters the oil separation section at the bottom of the tower to achieve oil-water separation, and the separated water phase flows out from the bottom pipeline of the tower and enters the water treatment section;

[0014] S7, the EVA solution from which the surfactant is removed in step S5 enters the water separation section at the top of the tower to achieve oil-water separation, and the separated oil phase EVA solution flows out from the pipeline at the top of the tower and enters the devolatilization section, and is processed by the devolatilization process to obtain a high-purity EVA elastomer or EVA resin.

[0015] Preferably, the demulsifier in step S1 is one of methanol, ethanol, isopropanol and ether, and the amount of the demulsifier is 1V%-25V% of the volume of the EVA emulsion.

[0016] Preferably, the solvent in step S2 is one of dichloroethane, chloroform, 1,2-dichloroethane, decahydronaphthalene, carbon disulfide, petroleum ether, xylene and trimethylbenzene, the stirring and dissolving temperature is 20° C.-80° C., and the concentration of the obtained EVA solution is 3wt%-25.5wt%.

[0017] Preferably, the extraction tower in step S3 is a rotary disk extraction tower, the height-to-diameter ratio of the rotary disk extraction tower is 1:1-10:1, and the temperature in the tower is 20°C-80°C.

[0018] Preferably, in step S3, the extractant is an aqueous solution, and a co-extractant is added to the aqueous solution.

[0019] Preferably, the auxiliary extraction agent is one of methanol, ethanol, isopropanol and dioxane, and the concentration of the auxiliary extraction agent in the extractant is 1wt%-10wt%.

[0020] Preferably, the volume flow ratio of the extractant to the EVA solution is 0.5:1-5.0:1, and the air velocity of the EVA solution is 1h -1 -25h -1 .

[0021] Therefore, the method for removing surfactant from EVA emulsion of the present invention has the following specific beneficial effects relative to the existing technology:

[0022] (1) Water is used as an extractant for the surfactant in the EVA solution. It has good solubility for the surfactant and is low in price, which is conducive to industrialization.

[0023] (2) operating the rotary disc extraction tower in countercurrent to allow the extractant and the EVA solution to be fully mixed and contacted under stirring, thereby achieving the purpose of completely removing the surfactant in the EVA;

[0024] (3) The operation process is simple, which can not only efficiently remove surfactants, but also remove other additives in the emulsion system to obtain pure EVA elastomer / resin, greatly improving production efficiency while improving product quality and reducing production costs.

[0025] The technical solution of the present invention is further described in detail below through embodiments. DETAILED DESCRIPTION

[0026] Example 1

[0027] A method for removing a surfactant from an EVA emulsion comprises the following steps:

[0028] S1. Add methanol to the EVA emulsion from the polymerization section, the amount of methanol is 7.4% of the volume of the EVA emulsion, stir and demulsify the EVA micelles to aggregate into larger particles, and centrifuge to obtain EVA solid;

[0029] S2, adding the EVA solid obtained in step S1 into petroleum ether, stirring and dissolving at 50° C. to obtain an EVA solution with a concentration of 10.5 wt %;

[0030] S3, the extractant is introduced from the top of the rotary disc extraction tower with a height-to-diameter ratio of 4, the extractant contains 4wt% of auxiliary extractant ethanol, and the space velocity of the extractant is 28.7h -1 , start the rotary disc extraction tower for stirring, and at the same time, introduce temperature-controlled water into the jacket of the rotary disc extraction tower to raise the temperature inside the tower to 50°C.

[0031] S4, the EVA solution obtained in step S2 is introduced from the bottom of the rotary disc extraction tower, and the space velocity of the EVA solution is 7h -1 , the volume flow ratio of the extractant to the EVA solution was 4.1:1;

[0032] S5, stirring the solution obtained by mixing the extractant in step S3 with the EVA solution in step S4 to allow them to be fully mixed and contacted, and the surfactant in the EVA solution enters the extraction phase;

[0033] S6, the surfactant-containing extract phase in step S5 enters the oil separation section at the bottom of the tower to achieve oil-water separation, and the separated water phase flows out from the bottom pipeline of the tower and enters the water treatment section;

[0034] S7, the EVA solution from which the surfactant is removed in step S5 enters the water separation section at the top of the tower to achieve oil-water separation, and the separated oil phase EVA solution flows out from the pipeline at the top of the tower and enters the devolatilization section, and is processed by the devolatilization process to obtain a high-purity EVA elastomer or EVA resin.

[0035] At this time, the surfactant content in EVA was measured to be 17.1 ppm.

[0036] Example 2

[0037] A method for removing a surfactant from an EVA emulsion comprises the following steps:

[0038] S1. Add ethanol to the EVA emulsion from the polymerization section, the amount of ethanol is 13.8% of the volume of the EVA emulsion, stir and demulsify the EVA micelles to aggregate into larger particles, and centrifuge to obtain EVA solid;

[0039] S2, adding the EVA solid obtained in step S1 into chloroform, stirring and dissolving at 55° C. to obtain an EVA solution with a concentration of 16.5 wt %;

[0040] S3, introducing an extractant from the top of a rotary disc extraction tower with a height-to-diameter ratio of 1, wherein the extractant contains 1 wt% of a co-extractant dioxane, and the space velocity of the extractant is 57.5 h -1 , start the rotary disc extraction tower for stirring, and at the same time, introduce temperature-controlled water into the jacket of the rotary disc extraction tower to raise the temperature inside the tower to 55°C.

[0041] S4, the EVA solution obtained in step S2 is introduced from the bottom of the rotary disc extraction tower, and the space velocity of the EVA solution is 25h-1 The volume flow ratio of the extractant to the EVA solution is 2.3:1;

[0042] S5, stirring the solution obtained by mixing the extractant in step S3 with the EVA solution in step S4 to allow them to be fully mixed and contacted, and the surfactant in the EVA solution enters the extraction phase;

[0043] S6, the surfactant-containing extract phase in step S5 enters the oil separation section at the bottom of the tower to achieve oil-water separation, and the separated water phase flows out from the bottom pipeline of the tower and enters the water treatment section;

[0044] S7, the EVA solution from which the surfactant is removed in step S5 enters the water separation section at the top of the tower to achieve oil-water separation, and the separated oil phase EVA solution flows out from the pipeline at the top of the tower and enters the devolatilization section, and is processed by the devolatilization process to obtain a high-purity EVA elastomer or EVA resin.

[0045] At this time, the surfactant content in the EVA was measured to be 18.5 ppm.

[0046] Example 3

[0047] A method for removing a surfactant from an EVA emulsion comprises the following steps:

[0048] S1. Add ether to the EVA emulsion from the polymerization section, the amount of ether is 12.2% of the volume of the EVA emulsion, stir and demulsify the EVA micelles to aggregate into larger particles, and centrifuge to obtain EVA solid;

[0049] S2, adding the EVA solid obtained in step S1 into decalin, stirring and dissolving at 60° C. to obtain an EVA solution with a concentration of 19.5 wt %;

[0050] S3, introducing an extractant from the top of a rotary disc extraction tower with a height-to-diameter ratio of 10, wherein the extractant contains 10 wt% of isopropanol as an auxiliary extractant, and the space velocity of the extractant is 22.4 h -1 , start the rotary disc extraction tower for stirring, and at the same time, introduce temperature-controlled water into the jacket of the rotary disc extraction tower to raise the temperature inside the tower to 60°C.

[0051] S4, the EVA solution obtained in step S2 is introduced from the bottom of the rotary disc extraction tower, and the space velocity of the EVA solution is 7h -1 The volume flow ratio of the extractant to the EVA solution is 3.2:1;

[0052] S5, stirring the solution obtained by mixing the extractant in step S3 with the EVA solution in step S4 to allow them to be fully mixed and contacted, and the surfactant in the EVA solution enters the extraction phase;

[0053] S6, the surfactant-containing extract phase in step S5 enters the oil separation section at the bottom of the tower to achieve oil-water separation, and the separated water phase flows out from the bottom pipeline of the tower and enters the water treatment section;

[0054] S7, the EVA solution from which the surfactant is removed in step S5 enters the water separation section at the top of the tower to achieve oil-water separation, and the separated oil phase EVA solution flows out from the pipeline at the top of the tower and enters the devolatilization section, and is processed by the devolatilization process to obtain a high-purity EVA elastomer or EVA resin.

[0055] At this time, the surfactant content in EVA was measured to be 13.9 ppm.

[0056] Example 4

[0057] A method for removing a surfactant from an EVA emulsion comprises the following steps:

[0058] S1. Add ethanol to the EVA emulsion from the polymerization section, the amount of ethanol is 10.6% of the volume of the EVA emulsion, stir and demulsify the EVA micelles to aggregate into larger particles, and centrifuge to obtain EVA solid;

[0059] S2, adding the EVA solid obtained in step S1 into chloroform, stirring and dissolving at 55° C. to obtain an EVA solution with a concentration of 24.0 wt %;

[0060] S3, introducing an extractant from the top of a rotary disc extraction tower with a height-to-diameter ratio of 7, wherein the extractant contains 4 wt% of methanol as an auxiliary extractant, and the space velocity of the extractant is 125 h -1 , start the rotary disc extraction tower for stirring, and at the same time, introduce temperature-controlled water into the jacket of the rotary disc extraction tower to raise the temperature inside the tower to 55°C.

[0061] S4, the EVA solution obtained in step S2 is introduced from the bottom of the rotary disc extraction tower, and the space velocity of the EVA solution is 25h -1 The volume flow ratio of the extractant to the EVA solution is 5.0:1;

[0062] S5, stirring the solution obtained by mixing the extractant in step S3 with the EVA solution in step S4 to allow them to be fully mixed and contacted, and the surfactant in the EVA solution enters the extraction phase;

[0063] S6, the surfactant-containing extract phase in step S5 enters the oil separation section at the bottom of the tower to achieve oil-water separation, and the separated water phase flows out from the bottom pipeline of the tower and enters the water treatment section;

[0064] S7, the EVA solution from which the surfactant is removed in step S5 enters the water separation section at the top of the tower to achieve oil-water separation, and the separated oil phase EVA solution flows out from the pipeline at the top of the tower and enters the devolatilization section, and is processed by the devolatilization process to obtain a high-purity EVA elastomer or EVA resin.

[0065] At this time, the surfactant content in EVA was measured to be 15.1 ppm.

[0066] Example 5

[0067] A method for removing a surfactant from an EVA emulsion comprises the following steps:

[0068] S1. Add methanol to the EVA emulsion from the polymerization section, the amount of methanol is 15.4% of the volume of the EVA emulsion, stir and demulsify the EVA micelles to aggregate into larger particles, and centrifuge to obtain EVA solid;

[0069] S2, adding the EVA solid obtained in step S1 into trimethylbenzene, stirring and dissolving at 80° C. to obtain an EVA solution with a concentration of 15.0 wt %;

[0070] S3, introducing an extractant from the top of a rotary disc extraction tower with a height-to-diameter ratio of 1, wherein the extractant contains 7 wt% of a co-extractant dioxane, and the space velocity of the extractant is 1.4 h -1 , start the rotary disc extraction tower for stirring, and at the same time, introduce temperature-controlled water into the jacket of the rotary disc extraction tower to raise the temperature inside the tower to 80°C.

[0071] S4, the EVA solution obtained in step S2 is introduced from the bottom of the rotary disc extraction tower, and the space velocity of the EVA solution is 1h -1 The volume flow ratio of the extractant to the EVA solution is 1.4:1;

[0072] S5, stirring the solution obtained by mixing the extractant in step S3 with the EVA solution in step S4 to allow them to be fully mixed and contacted, and the surfactant in the EVA solution enters the extraction phase;

[0073] S6, the surfactant-containing extract phase in step S5 enters the oil separation section at the bottom of the tower to achieve oil-water separation, and the separated water phase flows out from the bottom pipeline of the tower and enters the water treatment section;

[0074] S7, the EVA solution from which the surfactant is removed in step S5 enters the water separation section at the top of the tower to achieve oil-water separation, and the separated oil phase EVA solution flows out from the pipeline at the top of the tower and enters the devolatilization section, and is processed by the devolatilization process to obtain a high-purity EVA elastomer or EVA resin.

[0075] At this time, the surfactant content in EVA was measured to be 17.2 ppm.

[0076] Example 6

[0077] A method for removing a surfactant from an EVA emulsion comprises the following steps:

[0078] S1. Add isopropanol to the EVA emulsion from the polymerization section, the amount of isopropanol is 2.6% of the volume of the EVA emulsion, stir and demulsify the EVA micelles to aggregate into larger particles, and centrifuge to obtain EVA solid;

[0079] S2, adding the EVA solid obtained in step S1 into trimethylbenzene, stirring and dissolving at 50° C. to obtain an EVA solution with a concentration of 22.5 wt %;

[0080] S3, introducing an extractant from the top of a rotary disc extraction tower with a height-to-diameter ratio of 7, wherein the extractant contains 10 wt% of methanol as an auxiliary extractant, and the space velocity of the extractant is 6.5 h -1 , start the rotary disc extraction tower for stirring, and at the same time, introduce temperature-controlled water into the jacket of the rotary disc extraction tower to raise the temperature inside the tower to 50°C.

[0081] S4, the EVA solution obtained in step S2 is introduced from the bottom of the rotary disc extraction tower, and the space velocity of the EVA solution is 13h -1 The volume flow ratio of the extractant to the EVA solution is 0.5:1;

[0082] S5, stirring the solution obtained by mixing the extractant in step S3 with the EVA solution in step S4 to allow them to be fully mixed and contacted, and the surfactant in the EVA solution enters the extraction phase;

[0083] S6, the surfactant-containing extract phase in step S5 enters the oil separation section at the bottom of the tower to achieve oil-water separation, and the separated water phase flows out from the bottom pipeline of the tower and enters the water treatment section;

[0084] S7, the EVA solution from which the surfactant is removed in step S5 enters the water separation section at the top of the tower to achieve oil-water separation, and the separated oil phase EVA solution flows out from the pipeline at the top of the tower and enters the devolatilization section, and is processed by the devolatilization process to obtain a high-purity EVA elastomer or EVA resin.

[0085] At this time, the surfactant content in the EVA was measured to be 16.3 ppm.

[0086] Example 7

[0087] A method for removing a surfactant from an EVA emulsion comprises the following steps:

[0088] S1. Add ether to the EVA emulsion from the polymerization section, the amount of ether is 20.2% of the volume of the EVA emulsion, stir and demulsify the EVA micelles to aggregate into larger particles, and centrifuge to obtain EVA solid;

[0089] S2, adding the EVA solid obtained in step S1 into carbon disulfide, stirring and dissolving at 20° C. to obtain an EVA solution with a concentration of 9.0 wt %;

[0090] S3, introducing an extractant from the top of a rotary disc extraction tower with a height-to-diameter ratio of 4, wherein the extractant contains 4 wt% of isopropanol as an auxiliary extractant, and the space velocity of the extractant is 57.5 h -1 , start the rotary disc extraction tower for stirring, and at the same time, introduce temperature-controlled water into the jacket of the rotary disc extraction tower to raise the temperature inside the tower to 20°C.

[0091] S4, the EVA solution obtained in step S2 is introduced from the bottom of the rotary disc extraction tower, and the space velocity of the EVA solution is 25h -1 The volume flow ratio of the extractant to the EVA solution is 2.3:1;

[0092] S5, stirring the solution obtained by mixing the extractant in step S3 with the EVA solution in step S4 to allow them to be fully mixed and contacted, and the surfactant in the EVA solution enters the extraction phase;

[0093] S6, the surfactant-containing extract phase in step S5 enters the oil separation section at the bottom of the tower to achieve oil-water separation, and the separated water phase flows out from the bottom pipeline of the tower and enters the water treatment section;

[0094] S7, the EVA solution from which the surfactant is removed in step S5 enters the water separation section at the top of the tower to achieve oil-water separation, and the separated oil phase EVA solution flows out from the pipeline at the top of the tower and enters the devolatilization section, and is processed by the devolatilization process to obtain a high-purity EVA elastomer or EVA resin.

[0095] At this time, the surfactant content in EVA was measured to be 18.9 ppm.

[0096] Example 8

[0097] A method for removing a surfactant from an EVA emulsion comprises the following steps:

[0098] S1. Add isopropanol to the EVA emulsion from the polymerization section, the amount of isopropanol is 17.0% of the volume of the EVA emulsion, stir and demulsify the EVA micelles to aggregate into larger particles, and centrifuge to obtain EVA solid;

[0099] S2, adding the EVA solid obtained in step S1 into 1,2-dichloroethane, stirring and dissolving at 65° C. to obtain an EVA solution with a concentration of 4.5 wt %;

[0100] S3, the extractant is introduced from the top of the rotary disc extraction tower with a height-to-diameter ratio of 10, the extractant contains 4 wt% of auxiliary extractant ethanol, and the space velocity of the extractant is 2.3 h -1 , start the rotary disc extraction tower for stirring, and at the same time, introduce temperature-controlled water into the jacket of the rotary disc extraction tower to raise the temperature inside the tower to 65°C.

[0101] S4, the EVA solution obtained in step S2 is introduced from the bottom of the rotary disc extraction tower, and the space velocity of the EVA solution is 1h -1 The volume flow ratio of the extractant to the EVA solution is 2.3:1;

[0102] S5, stirring the solution obtained by mixing the extractant in step S3 with the EVA solution in step S4 to allow them to be fully mixed and contacted, and the surfactant in the EVA solution enters the extraction phase;

[0103] S6, the surfactant-containing extract phase in step S5 enters the oil separation section at the bottom of the tower to achieve oil-water separation, and the separated water phase flows out from the bottom pipeline of the tower and enters the water treatment section;

[0104] S7, the EVA solution from which the surfactant is removed in step S5 enters the water separation section at the top of the tower to achieve oil-water separation, and the separated oil phase EVA solution flows out from the pipeline at the top of the tower and enters the devolatilization section, and is processed by the devolatilization process to obtain a high-purity EVA elastomer or EVA resin.

[0105] At this time, the surfactant content in the EVA was measured to be 17.7 ppm.

[0106] Example 9

[0107] A method for removing a surfactant from an EVA emulsion comprises the following steps:

[0108] S1. Add methanol to the EVA emulsion from the polymerization section, the amount of methanol is 25.0% of the volume of the EVA emulsion, stir and demulsify the EVA micelles to aggregate into larger particles, and centrifuge to obtain EVA solid;

[0109] S2, adding the EVA solid obtained in step S1 into petroleum ether, stirring and dissolving at 40° C. to obtain an EVA solution with a concentration of 18.0 wt %;

[0110] S3, introducing an extractant from the top of a rotary disc extraction tower with a height-to-diameter ratio of 1, wherein the extractant contains 10 wt% of isopropanol as an auxiliary extractant, and the space velocity of the extractant is 65.0 h -1 , start the rotary disc extraction tower for stirring, and at the same time introduce temperature-controlled water into the jacket of the rotary disc extraction tower to raise the temperature inside the tower to 40°C.

[0111] S4, the EVA solution obtained in step S2 is introduced from the bottom of the rotary disc extraction tower, and the space velocity of the EVA solution is 13h -1 The volume flow ratio of the extractant to the EVA solution is 5.0:1;

[0112] S5, stirring the solution obtained by mixing the extractant in step S3 with the EVA solution in step S4 to allow them to be fully mixed and contacted, and the surfactant in the EVA solution enters the extraction phase;

[0113] S6, the surfactant-containing extract phase in step S5 enters the oil separation section at the bottom of the tower to achieve oil-water separation, and the separated water phase flows out from the bottom pipeline of the tower and enters the water treatment section;

[0114] S7, the EVA solution from which the surfactant is removed in step S5 enters the water separation section at the top of the tower to achieve oil-water separation, and the separated oil phase EVA solution flows out from the pipeline at the top of the tower and enters the devolatilization section, and is processed by the devolatilization process to obtain a high-purity EVA elastomer or EVA resin.

[0115] At this time, the surfactant content in the EVA was measured to be 16.5 ppm.

[0116] Example 10

[0117] A method for removing a surfactant from an EVA emulsion comprises the following steps:

[0118] S1, adding ether to the EVA emulsion from the polymerization section, the amount of ether being 1.0% of the volume of the EVA emulsion, stirring, and demulsifying the EVA micelles to aggregate into larger particles, and centrifugally filtering to obtain EVA solid;

[0119] S2, adding the EVA solid obtained in step S1 into carbon disulfide, stirring and dissolving at 35° C. to obtain an EVA solution with a concentration of 12.0 wt %;

[0120] S3, the extractant is introduced from the top of the rotary disc extraction tower with a height-to-diameter ratio of 10, the extractant contains 7wt% of the auxiliary extractant methanol, and the space velocity of the extractant is 41.6h -1 , start the rotary disc extraction tower for stirring, and at the same time, introduce temperature-controlled water into the jacket of the rotary disc extraction tower to raise the temperature inside the tower to 35°C.

[0121] S4, the EVA solution obtained in step S2 is introduced from the bottom of the rotary disc extraction tower, and the space velocity of the EVA solution is 13h -1 The volume flow ratio of the extractant to the EVA solution is 3.2:1;

[0122] S5, stirring the solution obtained by mixing the extractant in step S3 with the EVA solution in step S4 to allow them to be fully mixed and contacted, and the surfactant in the EVA solution enters the extraction phase;

[0123] S6, the surfactant-containing extract phase in step S5 enters the oil separation section at the bottom of the tower to achieve oil-water separation, and the separated water phase flows out from the bottom pipeline of the tower and enters the water treatment section;

[0124] S7, the EVA solution from which the surfactant is removed in step S5 enters the water separation section at the top of the tower to achieve oil-water separation, and the separated oil phase EVA solution flows out from the pipeline at the top of the tower and enters the devolatilization section, and is processed by the devolatilization process to obtain a high-purity EVA elastomer or EVA resin.

[0125] At this time, the surfactant content in the EVA was measured to be 18.4 ppm.

[0126] Embodiment 11

[0127] A method for removing a surfactant from an EVA emulsion comprises the following steps:

[0128] S1. Add ethanol to the EVA emulsion from the polymerization section, the amount of ethanol is 4.2% of the volume of the EVA emulsion, stir and demulsify the EVA micelles to aggregate into larger particles, and centrifuge to obtain EVA solid;

[0129] S2, adding the EVA solid obtained in step S1 into 1,2-dichloroethane, stirring and dissolving at 70° C. to obtain an EVA solution with a concentration of 21.0 wt %;

[0130] S3, the extractant is introduced from the top of the rotary disc extraction tower with a height-to-diameter ratio of 7, the extractant contains 7wt% of the auxiliary extractant methanol, and the space velocity of the extractant is 1.4h -1 , start the rotary disc extraction tower for stirring, and at the same time, introduce temperature-controlled water into the jacket of the rotary disc extraction tower to raise the temperature inside the tower to 70°C.

[0131] S4, the EVA solution obtained in step S2 is introduced from the bottom of the rotary disc extraction tower, and the space velocity of the EVA solution is 1h -1 The volume flow ratio of the extractant to the EVA solution is 1.4:1;

[0132] S5, stirring the solution obtained by mixing the extractant in step S3 with the EVA solution in step S4 to allow them to be fully mixed and contacted, and the surfactant in the EVA solution enters the extraction phase;

[0133] S6, the surfactant-containing extract phase in step S5 enters the oil separation section at the bottom of the tower to achieve oil-water separation, and the separated water phase flows out from the bottom pipeline of the tower and enters the water treatment section;

[0134] S7, the EVA solution from which the surfactant is removed in step S5 enters the water separation section at the top of the tower to achieve oil-water separation, and the separated oil phase EVA solution flows out from the pipeline at the top of the tower and enters the devolatilization section, and is processed by the devolatilization process to obtain a high-purity EVA elastomer or EVA resin.

[0135] At this time, the surfactant content in the EVA was measured to be 17.3 ppm.

[0136] Example 12

[0137] A method for removing a surfactant from an EVA emulsion comprises the following steps:

[0138] S1. Add methanol to the EVA emulsion from the polymerization section, the amount of methanol is 21.8% of the volume of the EVA emulsion, stir and demulsify the EVA micelles to aggregate into larger particles, and centrifuge to obtain EVA solid;

[0139] S2, adding the EVA solid obtained in step S1 into xylene, stirring and dissolving at 75° C. to obtain an EVA solution with a concentration of 3.0 wt %;

[0140] S3, introducing an extractant from the top of a rotary disc extraction tower with a height-to-diameter ratio of 1, wherein the extractant contains 7 wt% of a co-extractant dioxane, and the space velocity of the extractant is 60.8 h -1 , start the rotary disc extraction tower for stirring, and at the same time, introduce temperature-controlled water into the jacket of the rotary disc extraction tower to raise the temperature inside the tower to 75°C.

[0141] S4, the EVA solution obtained in step S2 is introduced from the bottom of the rotary disc extraction tower, and the space velocity of the EVA solution is 19h -1 The volume flow ratio of the extractant to the EVA solution is 3.2:1;

[0142] S5, stirring the solution obtained by mixing the extractant in step S3 with the EVA solution in step S4 to allow them to be fully mixed and contacted, and the surfactant in the EVA solution enters the extraction phase;

[0143] S6, the surfactant-containing extract phase in step S5 enters the oil separation section at the bottom of the tower to achieve oil-water separation, and the separated water phase flows out from the bottom pipeline of the tower and enters the water treatment section;

[0144] S7, the EVA solution from which the surfactant is removed in step S5 enters the water separation section at the top of the tower to achieve oil-water separation, and the separated oil phase EVA solution flows out from the pipeline at the top of the tower and enters the devolatilization section, and is processed by the devolatilization process to obtain a high-purity EVA elastomer or EVA resin.

[0145] At this time, the surfactant content in the EVA was measured to be 16.7 ppm.

[0146] Example 13

[0147] A method for removing a surfactant from an EVA emulsion comprises the following steps:

[0148] S1. Add isopropanol to the EVA emulsion from the polymerization section, the amount of isopropanol is 18.6% of the volume of the EVA emulsion, stir and demulsify the EVA micelles to aggregate into larger particles, and centrifuge to obtain EVA solid;

[0149] S2, adding the EVA solid obtained in step S1 into xylene, stirring and dissolving at 80° C. to obtain an EVA solution with a concentration of 7.5 wt %;

[0150] S3, introducing an extractant from the top of a rotary disc extraction tower with a height-to-diameter ratio of 4, wherein the extractant contains 10 wt% of ethanol as an auxiliary extractant, and the space velocity of the extractant is 0.5 h -1 , start the rotary disc extraction tower for stirring, and at the same time, introduce temperature-controlled water into the jacket of the rotary disc extraction tower to raise the temperature inside the tower to 80°C.

[0151] S4, the EVA solution obtained in step S2 is introduced from the bottom of the rotary disc extraction tower, and the space velocity of the EVA solution is 1h -1 The volume flow ratio of the extractant to the EVA solution is 0.5:1;

[0152] S5, stirring the solution obtained by mixing the extractant in step S3 with the EVA solution in step S4 to allow them to be fully mixed and contacted, and the surfactant in the EVA solution enters the extraction phase;

[0153] S6, the surfactant-containing extract phase in step S5 enters the oil separation section at the bottom of the tower to achieve oil-water separation, and the separated water phase flows out from the bottom pipeline of the tower and enters the water treatment section;

[0154] S7, the EVA solution from which the surfactant is removed in step S5 enters the water separation section at the top of the tower to achieve oil-water separation, and the separated oil phase EVA solution flows out from the pipeline at the top of the tower and enters the devolatilization section, and is processed by the devolatilization process to obtain a high-purity EVA elastomer or EVA resin.

[0155] At this time, the surfactant content in EVA was measured to be 15.9 ppm.

[0156] Embodiment 14

[0157] A method for removing a surfactant from an EVA emulsion comprises the following steps:

[0158] S1. Add ether to the EVA emulsion from the polymerization section, the amount of ether is 5.8% of the volume of the EVA emulsion, stir and demulsify the EVA micelles to aggregate into larger particles, and centrifuge to obtain EVA solid;

[0159] S2, adding the EVA solid obtained in step S1 into ethylene dichloride, stirring and dissolving at 50° C. to obtain an EVA solution with a concentration of 13.5 wt %;

[0160] S3, introducing an extractant from the top of a rotary disc extraction tower with a height-to-diameter ratio of 4, wherein the extractant contains 1 wt% of a co-extractant dioxane, and the space velocity of the extractant is 77.9 h -1, start the rotary disc extraction tower for stirring, and at the same time, introduce temperature-controlled water into the jacket of the rotary disc extraction tower to raise the temperature inside the tower to 50°C.

[0161] S4, the EVA solution obtained in step S2 is introduced from the bottom of the rotary disc extraction tower, and the space velocity of the EVA solution is 19h -1 The volume flow ratio of the extractant to the EVA solution is 4.1:1;

[0162] S5, stirring the solution obtained by mixing the extractant in step S3 with the EVA solution in step S4 to allow them to be fully mixed and contacted, and the surfactant in the EVA solution enters the extraction phase;

[0163] S6, the surfactant-containing extract phase in step S5 enters the oil separation section at the bottom of the tower to achieve oil-water separation, and the separated water phase flows out from the bottom pipeline of the tower and enters the water treatment section;

[0164] S7, the EVA solution from which the surfactant is removed in step S5 enters the water separation section at the top of the tower to achieve oil-water separation, and the separated oil phase EVA solution flows out from the pipeline at the top of the tower and enters the devolatilization section, and is processed by the devolatilization process to obtain a high-purity EVA elastomer or EVA resin.

[0165] At this time, the surfactant content in EVA was measured to be 16.1 ppm.

[0166] Embodiment 15

[0167] A method for removing a surfactant from an EVA emulsion comprises the following steps:

[0168] S1. Add ethanol to the EVA emulsion from the polymerization section, the amount of ethanol is 23.4% of the volume of the EVA emulsion, stir and demulsify the EVA micelles to aggregate into larger particles, and centrifuge to obtain EVA solid;

[0169] S2, adding the EVA solid obtained in step S1 into decalin, stirring and dissolving at 80° C. to obtain an EVA solution with a concentration of 25.5 wt %;

[0170] S3, the extractant is introduced from the top of the rotary disc extraction tower with a height-to-diameter ratio of 7, the extractant contains 1wt% of auxiliary extractant ethanol, and the space velocity of the extractant is 9.8h -1 , start the rotary disc extraction tower for stirring, and at the same time, introduce temperature-controlled water into the jacket of the rotary disc extraction tower to raise the temperature inside the tower to 80°C.

[0171] S4, the EVA solution obtained in step S2 is introduced from the bottom of the rotary disc extraction tower, and the space velocity of the EVA solution is 7h -1 The volume flow ratio of the extractant to the EVA solution is 1.4:1;

[0172] S5, stirring the solution obtained by mixing the extractant in step S3 with the EVA solution in step S4 to allow them to be fully mixed and contacted, and the surfactant in the EVA solution enters the extraction phase;

[0173] S6, the surfactant-containing extract phase in step S5 enters the oil separation section at the bottom of the tower to achieve oil-water separation, and the separated water phase flows out from the bottom pipeline of the tower and enters the water treatment section;

[0174] S7, the EVA solution from which the surfactant is removed in step S5 enters the water separation section at the top of the tower to achieve oil-water separation, and the separated oil phase EVA solution flows out from the pipeline at the top of the tower and enters the devolatilization section, and is processed by the devolatilization process to obtain a high-purity EVA elastomer or EVA resin.

[0175] At this time, the surfactant content in the EVA was measured to be 12.5 ppm.

[0176] Example 16

[0177] A method for removing a surfactant from an EVA emulsion comprises the following steps:

[0178] S1. Add isopropanol to the EVA emulsion from the polymerization section, the amount of isopropanol is 9.0% of the volume of the EVA emulsion, stir and demulsify the EVA micelles to aggregate into larger particles, and centrifuge to obtain EVA solid;

[0179] S2, adding the EVA solid obtained in step S1 into ethylene dichloride, stirring and dissolving at 40° C. to obtain an EVA solution with a concentration of 6.0 wt %;

[0180] S3, introducing an extractant from the top of a rotary disc extraction tower with a height-to-diameter ratio of 10, wherein the extractant contains 1 wt% of isopropanol as an auxiliary extractant, and the space velocity of the extractant is 9.5 h -1 , start the rotary disc extraction tower for stirring, and at the same time introduce temperature-controlled water into the jacket of the rotary disc extraction tower to raise the temperature inside the tower to 40°C.

[0181] S4, the EVA solution obtained in step S2 is introduced from the bottom of the rotary disc extraction tower, and the space velocity of the EVA solution is 19h -1 The volume flow ratio of the extractant to the EVA solution is 0.5:1;

[0182] S5, stirring the solution obtained by mixing the extractant in step S3 with the EVA solution in step S4 to allow them to be fully mixed and contacted, and the surfactant in the EVA solution enters the extraction phase;

[0183] S6, the surfactant-containing extract phase in step S5 enters the oil separation section at the bottom of the tower to achieve oil-water separation, and the separated water phase flows out from the bottom pipeline of the tower and enters the water treatment section;

[0184] S7, the EVA solution from which the surfactant is removed in step S5 enters the water separation section at the top of the tower to achieve oil-water separation, and the separated oil phase EVA solution flows out from the pipeline at the top of the tower and enters the devolatilization section, and is processed by the devolatilization process to obtain a high-purity EVA elastomer or EVA resin.

[0185] At this time, the surfactant content in the EVA was measured to be 16.3 ppm.

[0186] Therefore, the present invention provides a method for removing surfactants in EVA emulsions. The method is green and efficient, and has a simple operation process. It can not only efficiently remove surfactants, but also greatly improve production efficiency, improve the product quality of EVA elastomers and EVA resins, and reduce production costs.

[0187] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for removing surfactant from EVA emulsion, characterized in that: The specific steps include: S1, adding a demulsifier to the EVA emulsion from the polymerization section, the EVA micelles after demulsification aggregate into particles, and filtering to obtain EVA solid; S2, adding the EVA solid obtained in step S1 into a solvent, stirring and dissolving at a certain temperature to obtain an EVA solution; S3, introducing the extractant from the top of the extraction tower at a certain flow rate, opening the extraction tower for stirring, and simultaneously introducing temperature-controlled water into the jacket of the extraction tower to raise the temperature inside the extraction tower to a certain level; S4, introducing the EVA solution obtained in step S2 from the bottom of the extraction tower at a certain flow rate; S5, stirring the solution obtained by mixing the extractant in step S3 with the EVA solution in step S4, so that the surfactant in the EVA solution enters the extraction phase; S6, the surfactant-containing extract phase in step S5 enters the oil separation section at the bottom of the tower to achieve oil-water separation, and the separated water phase flows out from the bottom pipeline of the tower and enters the water treatment section; S7, the EVA solution from which the surfactant is removed in step S5 enters the water separation section at the top of the tower to achieve oil-water separation, and the separated oil phase EVA solution flows out from the pipeline at the top of the tower and enters the devolatilization section, and is processed by the devolatilization process to obtain a high-purity EVA elastomer or EVA resin; In step S1, the demulsifier is one of methanol, ethanol, isopropanol and ether, and the amount of the demulsifier is 1V%-25V% of the volume of the EVA emulsion; In step S2, the solvent is one of dichloroethane, chloroform, decahydronaphthalene, carbon disulfide, petroleum ether, xylene, and trimethylbenzene, the stirring and dissolving temperature is 20° C.-80° C., and the concentration of the obtained EVA solution is 3wt%-25.5wt%; In step S3, the extractant is an aqueous solution, and an auxiliary extractant is added to the aqueous solution; The auxiliary extraction agent is one of methanol, ethanol, isopropanol and dioxane, and the concentration of the auxiliary extraction agent in the extractant is 1wt%-10wt%.

2. A method for removing surfactant from EVA emulsion according to claim 1, characterized in that: The extraction tower in step S3 is a rotary disk extraction tower, the height-to-diameter ratio of the rotary disk extraction tower is 1:1-10:1, and the temperature in the tower is 20°C-80°C.

3. A method for removing surfactant from EVA emulsion according to claim 1, characterized in that: The volume flow ratio of the extractant to the EVA solution is 0.5:1-5.0:1, and the space velocity of the EVA solution is 1h -1 -25h -1 .