Method for recycling skim latex based on artificial latex preparation process

Abstract

The invention provides a skim recycling method based on an artificial latex preparation process, and belongs to the field of high polymer material synthesis and preparation. The method comprises the steps of skim treatment and skim recycling to prepare the artificial latex, and the skim treatment comprises the steps of mixing low-concentration skim generated in the preparation process of the artificial latex with insoluble cellulose, pulping, and carrying out adsorption treatment; and centrifuging, filtering and separating, and collecting the separated skim liquid to obtain the skim treatment liquid. The invention solves the problem of treatment of the byproduct low-concentration skim gum in the existing artificial latex preparation process, perfects and optimizes the artificial latex preparation process, reduces the discharge of wastewater, and realizes the green preparation process.

Description

Technical Field

[0001] The invention belongs to the field of polymer material synthesis and preparation, and particularly relates to a method for recycling low-concentration skim latex in the process of preparing artificial latex. Background Art

[0002] Medical latex products, due to contact with the human body, have high performance requirements and many limiting factors. They are strictly restricted latex products. They have high requirements for rubber properties including mechanical properties, air permeability, softness, etc., and have strict restrictions on protein content. At present, the latex raw materials widely used in latex products include PVC latex, natural latex, synthetic latex, etc.; among them, PVC latex products have high strength and low price, but poor air permeability and insufficient softness; natural latex has good flexibility and high strength, but casein in natural latex is easy to cause allergic reactions, and it is very difficult to remove protein from natural latex; synthetic latex such as chloroprene, nitrile, and styrene-butadiene latex adopt free radical polymerization, and the stereoregularity of the polymer structure is poor and the gel content is high, and the mechanical properties and flexibility of its products are greatly different.

[0003] By polymerizing isoprene monomers with rare earths, polyisoprene rubber with a structure similar to natural rubber can be obtained. Artificial polyisoprene rubber imitating natural latex can be prepared by post-emulsification, which does not contain protein and has various properties close to natural latex. Chinese patent CN201210332915.3 discloses a method for directly preparing polyisoprene latex using polyisoprene glue. The method uses an active anion solution polymerization method to prepare polyisoprene glue with different molecular weights and narrow distributions, and then prepares artificial latex through emulsification, desolvation of polyisoprene crude latex, and centrifugal concentration. Chinese patent ZL116891543A discloses a method for preparing artificial latex using a parallel-series continuous kettle distillation method, which greatly simplifies the process flow. The above inventions all adopt the four steps of emulsification, continuous distillation, reduced pressure distillation and centrifugal concentration of rubber liquid to obtain high-concentration artificial latex, but at the same time produce a large amount of low-concentration skim latex. If it is directly recycled instead of the emulsifier aqueous solution, the prepared latex particle size is too large, resulting in poor latex stability and unqualified products. How to deal with and recycle low-concentration skim latex is a thorny problem in the industry. Summary of the invention

[0004] The purpose of the present invention is to provide a method for recycling skim latex based on the preparation process of artificial latex, so as to solve the problems existing in the prior art mentioned in the above background technology.

[0005] In order to achieve the above object, the present invention adopts the following technical solution.

[0006] The present invention provides a method for recycling skim latex based on a process for preparing artificial latex, comprising the following steps: (1) Skim cleaning treatment ① Cellulose beating treatment: The low-concentration latex produced in the process of preparing artificial latex is mixed with insoluble cellulose for beating and adsorption treatment; ② Separation treatment: centrifuge and filter the skim latex after adsorption treatment, collect the skim latex liquid after separation, and obtain skim latex treatment liquid for standby use; (2) Recycling of skim latex to prepare artificial latex ① All or part of the skim latex solution obtained after the treatment in step (1) is mixed with a fresh emulsifier, stirred at 50-60°C for 4-8h, and the pH is adjusted to 10-12 with KOH to prepare a composite skim latex solution; ② Adding the compounded latex liquid to the rubber latex, performing emulsification operation, and then performing normal pressure distillation, reduced pressure distillation, and centrifugal concentration operations to prepare a high-concentration artificial latex; in the process of preparing the high-concentration artificial latex, the low-concentration latex produced is recycled using the above steps.

[0007] Furthermore, in step (1)-①, the insoluble cellulose and low-concentration skim latex are mixed in a mass ratio of 5-50:100, the rubber content in the low-concentration skim latex is 0.5-1wt%, and the emulsifier concentration is 2-4.5wt%; the beating is carried out by stirring and beating at room temperature for 4-6h.

[0008] Furthermore, in step (1)-①, in step (1)-①, the insoluble cellulose includes at least one of cellulose fibers, lignin, and cellulose particles.

[0009] Preferably, the cellulose fiber is selected from at least one of cotton, short fibers of linen, and pulp slurry.

[0010] Preferably, the lignin is natural unmodified lignin or modified lignin excluding sulfonated lignin.

[0011] Preferably, the cellulose particles are selected from at least one of cellulose microcrystals and nanocellulose.

[0012] Furthermore, in step (1)-②, the centrifugal speed is 5000-10000 rpm, and the filtration is performed using a 200-400 mesh filter.

[0013] Furthermore, in step (2)-①, the skim latex treatment liquid is first mixed with deionized water in a mass ratio of 1:1 to form a skim latex treatment aqueous solution, and the skim latex treatment aqueous solution is then mixed with a fresh emulsifier to form a composite skim latex aqueous solution, which is used for rubber latex emulsification operation, and then subjected to normal pressure distillation, reduced pressure distillation, and centrifugal concentration operations to prepare a high-concentration artificial latex.

[0014] Furthermore, in step (2)-①, the mass ratio of the skim latex treatment liquid used in the preparation process of the compounded skim latex liquid or the compounded skim latex aqueous solution is 10-100%; the fresh emulsifier includes a main emulsifier, an auxiliary emulsifier and a stabilizer in a mass ratio of 2:3:1; the main emulsifier accounts for 2-5% of the mass of the compounded skim latex liquid or the compounded skim latex aqueous solution.

[0015] Preferably, the main emulsifier is sodium dodecylbenzene sulfonate, the auxiliary emulsifier is potassium disproportionate rosin acid, and the stabilizer is Tween 80.

[0016] Furthermore, in step (2)-②, the step of preparing high-concentration artificial latex specifically includes: S1. Emulsification of rubber glue: emulsifying the rubber glue and the compound glue serum or the compound glue serum aqueous solution at a mass ratio of 1:1. The specific operation steps are as follows: at room temperature, firstly adding a part of the compound glue serum or the compound glue serum aqueous solution to the rubber glue, stirring at a speed of 400-500r / min for 30-60min to form an oil-in-water pre-emulsified glue; then adding the remaining compound glue serum or the compound glue serum aqueous solution to the above-mentioned oil-in-water pre-emulsified liquid, using a shear emulsification method, emulsifying at a shear speed of 3000-4000rpm for 3-5min; subsequently increasing the shearing machine speed within the range of 4000-5000rpm, shearing homogenization for 5-10min, to form a stable water-in-oil crude emulsion; S2, continuous distillation: when hexane is used as the solvent, atmospheric distillation is first performed, the distillation temperature is 70-72°C, the average residence time is 6-8h, 80-90% of the total amount of solvent is removed, and then vacuum distillation is performed, and it is maintained at 80°C and 60KPa for 1h to remove the residual solvent to obtain a dilute emulsion; when pentane is used as the solvent, the distillation temperature is 45-50°C, the average residence time is 7-9h, 80-90% of the total amount of solvent is removed, and then vacuum distillation is performed, and it is maintained at 60°C and 60KPa for 1h to remove the residual solvent to obtain a dilute emulsion; S3, centrifugal concentration: the dilute emulsion is placed in a high-speed centrifuge, the speed is set to 6000-10000rpm, the centrifugal time is 5-20min, and the high-concentration artificial latex with a solid content of 50-60% is obtained by centrifugal concentration, and low-concentration skim latex is obtained at the same time.

[0017] Preferably, in step S1, the rubber types used in the rubber glue include but are not limited to polyisoprene rubber, polybutadiene rubber, styrene-butadiene rubber, with a number average molecular weight of 50,000-800,000. The rubber glue is obtained by dissolving a rubber block in a solvent, or directly obtained by polymerizing a rubber monomer in a solvent. The solvent is selected from one or more of C5-C9 straight-chain alkanes, C5-C9 cycloalkanes, and benzene. The mass concentration of rubber in the rubber glue is between 2-15%.

[0018] Compared with the prior art, the present invention has the following beneficial technical effects: the present invention adopts the skim latex generated in the process of preparing artificial latex, and mixes it with insoluble cellulose for pulping, adsorption and separation treatment, removes low-concentration rubber particles in the skim latex liquid, retains the emulsifier component in the skim latex liquid, and can recycle all or part of it, and performs emulsification, atmospheric distillation, reduced-pressure distillation, and centrifugal concentration operations on the rubber latex to complete the process of preparing artificial latex, solves the problem of treating the by-product low-concentration skim latex in the current process of preparing artificial latex, improves and optimizes the process of preparing artificial latex, reduces and reduces the discharge of wastewater, and realizes a green preparation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a graph showing the particle size change of the skim latex before being treated with nanocellulose in Example 1; Figure 2 is a graph showing the change in particle size of the skim latex after it is treated with nanocellulose in Example 1; Figure 3 is the particle size distribution diagram of the artificial latex in Example 3; Figure 4 is the particle size distribution diagram of the artificial latex in Example 5; Figure 5 is the particle size distribution diagram of the artificial latex in Example 8; Figure 6 This is the particle size distribution diagram of the artificial latex in Example 9. DETAILED DESCRIPTION

[0020] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0021] Comparative Example 1: Production process of low-concentration skim latex as a byproduct of artificial latex The method disclosed in Chinese patent ZL201210332915.3 is used to prepare artificial latex, which specifically includes: Sol preparation: a certain amount of rare earth isoprene rubber is added to hexane, stirred and refluxed at 55°C for 14 hours to dissolve, and a rubber glue solution with a rubber solid content of 8% is prepared; 1% sodium dodecylbenzene sulfonate, 1.5% potassium disproportionate rosin acid, 0.5% Tween 80 and the balance deionized water are added to the container in sequence according to the mass ratio, and the pH is adjusted to 12 with KOH to obtain an emulsifier aqueous solution; Emulsification process: the rubber glue and the emulsifier aqueous solution are mixed and emulsified synchronously in a mass ratio of 1:1. Specifically, at room temperature, 1 / 3 of the emulsifier aqueous solution is first added to the rubber glue for pre-emulsification, and stirred at a speed of 450r / min for 45 minutes to form an oil-in-water pre-emulsified glue; then the remaining emulsifier aqueous solution is slowly added, and shear emulsification is performed at the same time, and emulsification is performed at a shear speed of 3500rpm for 4 minutes; the shear speed is continued to be increased for shear homogenization, and homogenization is performed at a shear speed of 4500rpm for 7 minutes to form a stable water-in-oil crude emulsion; Distillation to remove solvent: A two-stage method is used to remove solvent from the crude emulsion. First, atmospheric distillation is performed at a distillation temperature of 71°C and an average residence time of 7 hours to remove 85% of the total solvent. Then, vacuum distillation is performed at 80°C and 60KPa for 1 hour to remove residual solvent and obtain a dilute emulsion that is almost free of solvent. Centrifugal concentration: The dilute emulsion is subjected to high-speed centrifugation, with the centrifugal speed set at 6000 rpm and the centrifugal time set at 20 min, to prepare a high-concentration artificial latex with a solid content of 50%, and at the same time obtain a by-product of low-concentration skim latex.

[0022] Comparative Test Example 1 High Concentration Artificial Latex Particle Size Test The particle size of the high-concentration artificial latex prepared in Comparative Example 1 was tested using a laser particle size analyzer.

[0023] After testing, the average particle size of the high-concentration artificial latex prepared in this comparative example is 800nm.

[0024] Comparative Test Example 2 Analysis of skim latex characteristic parameters (1) Skim latex content test: Weigh 10g of skim latex and place it in an oven to heat at 105℃. Measure the weight every 10 minutes until the value remains unchanged after three consecutive measurements. After constant weight is obtained, record the weight of the evaporation residue and compare it with the weight of the skim latex before evaporation to obtain the skim latex solid content value. The skim latex solid content of many batches is between 3.1% and 3.5% (mass ratio), which includes rubber and emulsifier. Then wash the evaporation residue with 50g of ethanol three times and dry it at 105℃ to constant weight. Compare it with the weight of the skim latex before evaporation to obtain the rubber solid content value in the skim latex. The rubber content in many batches of skim latex is between 1.1% and 1.5% (mass ratio).

[0025] (2) Analysis of skim latex particle size: A laser particle size analyzer was used to analyze the skim latex. The skim latex was diluted with 0.6% sodium dodecylbenzene sulfonate solution to a concentration gradient of 0.04-0.07% (mass ratio) and then the particle size analysis test was performed. The average particle size of the skim latex was 600nm.

[0026] (3) Emulsification characteristics test of by-product skim milk of artificial latex: In Example 1, the by-product low-concentration skim milk was used to prepare high-concentration artificial latex instead of the emulsifier aqueous solution, and the particle size of the high-concentration artificial latex was tested using a laser particle size analyzer.

[0027] The specific method of using skim milk instead of emulsifier aqueous solution to prepare high-concentration artificial latex is as follows: Sol emulsification: add cis-1,4-polyisoprene rubber to hexane, stir and reflux at 50°C for 12 hours to dissolve, and prepare a rubber glue with a rubber solid content of 8%; mix and emulsify the rubber glue and skim clear in a mass ratio of 1:1, specifically, at room temperature, first add 1 / 3 of the skim clear to the rubber glue for pre-emulsification, and stir at a speed of 400r / min for 30 minutes to form an oil-in-water pre-emulsified glue; then slowly add the remaining skim clear and shear emulsify at the same time, emulsify at a shear speed of 3000rpm for 3 minutes; continue to increase the speed of the shear machine for shear homogenization, and homogenize at a shear speed of 4000rpm for 5 minutes to form a stable water-in-oil crude emulsion; Distillation to remove solvent: A two-stage method is used to remove solvent from the crude emulsion. First, atmospheric distillation is performed at a distillation temperature of 70°C and an average residence time of 6 hours to remove 80% of the total solvent. Then, vacuum distillation is performed at 80°C and 60KPa for 1 hour to remove residual solvent and obtain a dilute emulsion that is almost free of solvent. Centrifugal concentration: The dilute emulsion is subjected to high-speed centrifugation, with the centrifugal speed set at 6000 rpm and the centrifugal time set at 20 min to prepare a high-concentration artificial latex with a solid content of 50%.

[0028] After testing, based on the method of Comparative Example 1, the average particle size of the high-concentration artificial latex prepared by using skim milk instead of the emulsifier aqueous solution is 1200nm.

[0029] Example 1 Nanocellulose treatment of skim latex Weigh nanocellulose and skim latex, mix them in a mass ratio of 5-50:100, stir and beat at room temperature for 4-6 hours, then slowly add them into a butterfly centrifuge for centrifugal separation, set the centrifugal speed to 10000rpm, shut down the centrifuge regularly, clean the nanocellulose rubber adsorbent attached to the butterfly, collect the separated treatment liquid, and then filter it with a 400-mesh net to obtain the treated skim latex, i.e. skim latex treatment liquid.

[0030] Please refer to the attached Figure 1-2 , as tested by a laser particle size analyzer, the average particle size of the skim latex treated in this embodiment is 120nm.

[0031] Example 2 Lignin treatment of skim latex Weigh unmodified lignin and skim latex, mix them in a mass ratio of 5-50:100, stir and beat at room temperature for 4-6 hours, then slowly add them into a butterfly centrifuge for centrifugal separation, set the centrifugal speed to 10000rpm, shut down the centrifuge regularly, clean the lignin rubber adsorbent attached to the butterfly, collect the separated treatment liquid, and then filter it with a 200-mesh net to obtain the treated skim latex, i.e. skim latex treatment liquid.

[0032] The laser particle size analyzer test showed that the average particle size of the skim latex treated in this embodiment was 130 nm.

[0033] Example 3 Pulp treatment skim latex Weigh a pulp slurry with a concentration of 25wt%, mix it with skim latex in a mass ratio of 5-15:100, stir and beat at room temperature for 4-6h, then slowly add it into a butterfly centrifuge for centrifugal separation, set the centrifugal speed to 10000rpm, shut down the centrifuge regularly, clean the pulp fiber rubber adsorbent attached to the butterfly, collect the separated treatment liquid, and then filter it with a 200-mesh net to obtain the treated skim latex, i.e. skim latex treatment liquid.

[0034] Please refer to the attached Figure 3 , as tested by a laser particle size analyzer, the average particle size of the skim latex treated in this embodiment is 130nm.

[0035] Comparative Example 2: Direct recycling of latex to prepare artificial latex Sol emulsification: add a certain amount of rare earth polyisoprene rubber to a hexane solvent, stir at 50°C for 10 hours, and prepare a polyisoprene rubber glue solution with a mass ratio of 8%; add 2% of the total amount of sodium dodecylbenzene sulfonate, 3% of potassium disproportionate rosin acid, and 1% of Tween 80 to the low-concentration glue solution obtained in Comparative Example 1, stir at 55°C for 4 hours, and use KOH to adjust the pH to 10 to obtain a glue solution; Emulsification process: emulsify the rubber glue and the glue clear aqueous solution in a mass ratio of 1:1. Specifically, at room temperature, first add 1 / 3 of the glue clear aqueous solution to the rubber glue for pre-emulsification, and stir at a speed of 400r / min for 30min to form an oil-in-water pre-emulsified glue; then slowly add the remaining glue clear solution and shear emulsify at the same time, emulsify at a shear speed of 3000rpm for 3min; continue to increase the speed of the shear machine for shear homogenization, and homogenize at a shear speed of 4000rpm for 5min to form a stable water-in-oil crude emulsion; Distillation to remove solvent: A two-stage method is used to remove solvent from the crude emulsion. First, atmospheric distillation is performed at a distillation temperature of 45°C and an average residence time of 7 hours to remove 80% of the total solvent. Then, vacuum distillation is performed at 80°C and 60KPa for 1 hour to remove residual solvent and obtain a dilute emulsion that is almost free of solvent. High-speed centrifugal concentration: The dilute emulsion was subjected to high-speed centrifugation, with the centrifugal speed set at 6000 rpm and the centrifugal time set at 5 min to prepare a high-concentration artificial latex with a solid content of 55%.

[0036] The average particle size of the artificial latex in this comparative example was 1200 nm as measured by a laser particle size analyzer.

[0037] Example 4 Treatment of latex for recycling to prepare artificial latex Sol emulsification: adding a certain amount of rare earth polyisoprene rubber to a hexane solvent, stirring at 50° C. for 10 hours, and preparing a polyisoprene rubber glue solution with a mass ratio of 8%; adding 2% of the total amount of sodium dodecylbenzene sulfonate, 3% of potassium disproportionate rosin acid, and 1% of Tween 80 to the treated glue solution obtained in Example 1, stirring at 55° C. for 4 hours, and adjusting the pH to 10 with KOH to obtain a composite glue solution; Emulsification process: emulsify the rubber glue liquid and the compound glue clear liquid in a mass ratio of 1:1. Specifically, at room temperature, first add 1 / 3 of the compound glue clear liquid to the rubber glue liquid for pre-emulsification, and stir at a speed of 400r / min for 30 minutes to form an oil-in-water pre-emulsified glue liquid; then slowly add the remaining compound glue clear liquid and shear emulsify at the same time, emulsify at a shear speed of 3000rpm for 3min; continue to increase the speed of the shear machine for shear homogenization, and homogenize at a shear speed of 4000rpm for 5min to form a stable water-in-oil crude emulsion; Distillation to remove solvent: A two-stage method is used to remove solvent from the crude emulsion. First, atmospheric distillation is performed at a distillation temperature of 45°C and an average residence time of 7 hours to remove 80% of the total solvent. Then, vacuum distillation is performed at 60°C and 60KPa for 1 hour to remove residual solvent and obtain a dilute emulsion that is almost free of solvent. High-speed centrifugal concentration: The dilute emulsion was subjected to high-speed centrifugation, with the centrifugal speed set at 6000 rpm and the centrifugal time set at 5 min to prepare a high-concentration artificial latex with a solid content of 55%.

[0038] The average particle size of the artificial latex in this embodiment is 700 nm as measured by a laser particle size analyzer.

[0039] Example 5 Treatment of latex solution for recycling to prepare artificial latex Sol emulsification: adding a certain amount of rare earth polyisoprene rubber to a hexane solvent, stirring at 50° C. for 10 hours, and preparing a polyisoprene rubber glue solution with a mass ratio of 8%; adding 2% of the total amount of sodium dodecylbenzene sulfonate, 3% of potassium disproportionate rosin acid, and 1% of Tween 80 to the treated glue solution obtained in Example 2, stirring at 55° C. for 4 hours, and adjusting the pH to 10 with KOH to obtain a composite glue solution; Emulsification process: emulsify the rubber glue liquid and the compound glue clear liquid in a mass ratio of 1:1. Specifically, at room temperature, first add 1 / 3 of the compound glue clear liquid to the rubber glue liquid for pre-emulsification, and stir at a speed of 400r / min for 30min to form an oil-in-water pre-emulsified glue liquid; then slowly add the remaining compound glue clear liquid and shear emulsify at the same time, emulsify at a shear speed of 3000rpm for 3min; continue to increase the speed of the shear machine for shear homogenization, and homogenize at a shear speed of 4000rpm for 5min to form a stable water-in-oil crude emulsion; Distillation to remove solvent: A two-stage method is used to remove solvent from the crude emulsion. First, atmospheric distillation is performed at a distillation temperature of 45°C and an average residence time of 7 hours to remove 80% of the total solvent. Then, vacuum distillation is performed at 60°C and 60KPa for 1 hour to remove residual solvent and obtain a dilute emulsion that is almost free of solvent. High-speed centrifugal concentration: The dilute emulsion was subjected to high-speed centrifugation, with the centrifugal speed set at 6000 rpm and the centrifugal time set at 5 min to prepare a high-concentration artificial latex with a solid content of 55%.

[0040] Please refer to the attached Figure 4 , as measured by a laser particle size analyzer, the average particle size of the artificial latex of this embodiment is 670nm.

[0041] Example 6 Treatment of latex solution for recycling to prepare artificial latex Sol emulsification: adding a certain amount of rare earth polyisoprene rubber to a hexane solvent, stirring at 50° C. for 10 hours, and preparing a polyisoprene rubber glue solution with a mass ratio of 8%; adding 2% of the total amount of sodium dodecylbenzene sulfonate, 3% of potassium disproportionate rosin acid, and 1% of Tween 80 to the treated glue solution obtained in Example 3, stirring at 55° C. for 4 hours, and adjusting the pH to 10 with KOH to obtain a composite glue solution; Emulsification process: emulsify the rubber glue liquid and the compound glue clear liquid in a mass ratio of 1:1. Specifically, at room temperature, first add 1 / 3 of the compound glue clear liquid to the rubber glue liquid for pre-emulsification, and stir at a speed of 400r / min for 30 minutes to form an oil-in-water pre-emulsified glue liquid; then slowly add the remaining compound glue clear liquid and shear emulsify at the same time, emulsify at a shear speed of 3000rpm for 3min; continue to increase the speed of the shear machine for shear homogenization, and homogenize at a shear speed of 4000rpm for 5min to form a stable water-in-oil crude emulsion; Distillation to remove solvent: A two-stage method is used to remove solvent from the crude emulsion. First, atmospheric distillation is performed at a distillation temperature of 45°C and an average residence time of 7 hours to remove 80% of the total solvent. Then, vacuum distillation is performed at 60°C and 60KPa for 1 hour to remove residual solvent and obtain a dilute emulsion that is almost free of solvent. High-speed centrifugal concentration: The dilute emulsion was subjected to high-speed centrifugation, with the centrifugal speed set at 6000 rpm and the centrifugal time set at 5 min to prepare a high-concentration artificial latex with a solid content of 55%.

[0042] The average particle size of the artificial latex in this embodiment is 680 nm as measured by a laser particle size analyzer.

[0043] Example 7 Treatment of latex solution for recycling to prepare artificial latex Sol emulsification: adding a certain amount of rare earth polyisoprene rubber to a hexane solvent, stirring at 50°C for 10 hours, and preparing a polyisoprene rubber glue solution with a mass ratio of 8%; mixing the treated glue solution obtained in Example 1 with deionized water at a mass ratio of 1:1, and then adding 2% of the total amount of sodium dodecylbenzene sulfonate, 3% of potassium disproportionate rosin acid, and 1% of Tween 80, stirring at 55°C for 4 hours, and adjusting the pH to 10 with KOH to obtain a composite glue solution; Emulsification process: emulsify the rubber glue and the compound glue clear water solution in a mass ratio of 1:1. Specifically, at room temperature, first add 1 / 3 of the compound glue clear water solution to the rubber glue for pre-emulsification, and stir at a speed of 400r / min for 30min to form an oil-in-water pre-emulsified glue solution; then slowly add the remaining compound glue clear water solution and shear emulsify at the same time, emulsify at a shear speed of 3000rpm for 3min; continue to increase the speed of the shear machine for shear homogenization, and homogenize at a shear speed of 4000rpm for 5min to form a stable water-in-oil crude emulsion; Distillation to remove solvent: A two-stage method is used to remove solvent from the crude emulsion. First, atmospheric distillation is performed at a distillation temperature of 45°C and an average residence time of 7 hours to remove 80% of the total solvent. Then, vacuum distillation is performed at 60°C and 60KPa for 1 hour to remove residual solvent and obtain a dilute emulsion that is almost free of solvent. High-speed centrifugal concentration: The dilute emulsion was subjected to high-speed centrifugation, with the centrifugal speed set at 6000 rpm and the centrifugal time set at 5 min to prepare a high-concentration artificial latex with a solid content of 55%.

[0044] The average particle size of the artificial latex in this embodiment is 500 nm as measured by a laser particle size analyzer.

[0045] Example 8 Treatment of latex solution for recycling to prepare artificial latex Sol emulsification: adding a certain amount of rare earth polyisoprene rubber to a hexane solvent, stirring at 50°C for 10 hours, and preparing a polyisoprene rubber glue solution with a mass ratio of 8%; mixing the treated glue solution obtained in Example 2 with deionized water at a mass ratio of 1:1, and then adding 2% of the total amount of sodium dodecylbenzene sulfonate, 3% of potassium disproportionate rosin acid, and 1% of Tween 80, stirring at 55°C for 4 hours, and adjusting the pH to 10 with KOH to obtain a composite glue solution; Emulsification process: emulsify the rubber glue and the compound glue clear water solution in a mass ratio of 1:1. Specifically, at room temperature, first add 1 / 3 of the compound glue clear water solution to the rubber glue for pre-emulsification, and stir at a speed of 400r / min for 30min to form an oil-in-water pre-emulsified glue solution; then slowly add the remaining compound glue clear water solution and shear emulsify at the same time, emulsify at a shear speed of 3000rpm for 3min; continue to increase the shear speed for shear homogenization, and homogenize at a shear speed of 4000rpm for 5min to form a stable water-in-oil crude emulsion; Distillation to remove solvent: A two-stage method is used to remove solvent from the crude emulsion. First, atmospheric distillation is performed at a distillation temperature of 45°C and an average residence time of 7 hours to remove 80% of the total solvent. Then, vacuum distillation is performed at 60°C and 60KPa for 1 hour to remove residual solvent and obtain a dilute emulsion that is almost free of solvent. High-speed centrifugal concentration: The dilute emulsion was subjected to high-speed centrifugation, with the centrifugal speed set at 6000 rpm and the centrifugal time set at 5 min to prepare a high-concentration artificial latex with a solid content of 55%.

[0046] Please refer to the attached Figure 5 , as measured by a laser particle size analyzer, the average particle size of the artificial latex in this embodiment is 450nm.

[0047] Example 9 Treatment of latex for recycling to prepare artificial latex Sol emulsification: adding a certain amount of rare earth polyisoprene rubber to a hexane solvent, stirring at 50°C for 10 hours, and preparing a polyisoprene rubber glue solution with a mass ratio of 8%; mixing the treated glue solution obtained in Example 3 with deionized water at a mass ratio of 1:1, and then adding 2% of the total amount of sodium dodecylbenzene sulfonate, 3% of potassium disproportionate rosin acid, and 1% of Tween 80, stirring at 55°C for 4 hours, and adjusting the pH to 10 with KOH to obtain a composite glue solution; Emulsification process: emulsify the rubber glue and the compound glue clear water solution in a mass ratio of 1:1. Specifically, at room temperature, first add 1 / 3 of the compound glue clear water solution to the rubber glue for pre-emulsification, and stir at a speed of 400r / min for 30min to form an oil-in-water pre-emulsified glue solution; then slowly add the remaining compound glue clear water solution and shear emulsify at the same time, emulsify at a shear speed of 3000rpm for 3min; continue to increase the shear speed for shear homogenization, and homogenize at a shear speed of 4000rpm for 5min to form a stable water-in-oil crude emulsion; Distillation to remove solvent: A two-stage method is used to remove solvent from the crude emulsion. First, atmospheric distillation is performed at a distillation temperature of 45°C and an average residence time of 7 hours to remove 80% of the total solvent. Then, vacuum distillation is performed at 60°C and 60KPa for 1 hour to remove residual solvent and obtain a dilute emulsion that is almost free of solvent. High-speed centrifugal concentration: The dilute emulsion was subjected to high-speed centrifugation, with the centrifugal speed set at 6000 rpm and the centrifugal time set at 5 min to prepare a high-concentration artificial latex with a solid content of 55%.

[0048] Please refer to the attached Figure 6 , as measured by a laser particle size analyzer, the average particle size of the artificial latex in this embodiment is 390nm.

Claims

1. A method for recycling skim latex based on the preparation process of artificial latex, characterized in that: The following steps are involved: (1) Skim cleaning treatment ① Cellulose beating treatment: The low-concentration latex produced in the process of preparing artificial latex is mixed with insoluble cellulose for beating and adsorption treatment; ② Separation treatment: centrifuge and filter the skim latex after adsorption treatment, collect the skim latex liquid after separation, and obtain skim latex treatment liquid for standby use; (2) Recycling of skim latex to prepare artificial latex ① All or part of the skim latex solution obtained after the treatment in step (1) is mixed with a fresh emulsifier, stirred at 50-60°C for 4-8h, and the pH is adjusted to 10-12 with KOH to prepare a composite skim latex solution; ② Adding the compounded latex liquid to the rubber latex, performing emulsification operation, and then performing normal pressure distillation, reduced pressure distillation, and centrifugal concentration operations to prepare a high-concentration artificial latex; in the process of preparing the high-concentration artificial latex, the low-concentration latex produced is recycled using the above steps.

2. A method for recycling skim latex based on a process for preparing artificial latex according to claim 1, characterized in that: In step (1)-①, the insoluble cellulose and low-concentration skim latex are mixed in a mass ratio of 5-50:100, the rubber content in the low-concentration skim latex is 0.5-1wt%, and the emulsifier concentration is 2-4.5wt%; the beating is carried out by stirring and beating at room temperature for 4-6h.

3. A method for recycling skim latex based on a process for preparing artificial latex according to claim 2, characterized in that: In step (1)-①, the insoluble cellulose includes at least one of cellulose fibers, lignin, and cellulose particles.

4. A method for recycling skim latex based on a process for preparing artificial latex according to claim 3, characterized in that: The cellulose fiber is selected from at least one of cotton, short fibers of hemp, and pulp slurry; the lignin is selected from natural unmodified lignin or modified lignin excluding sulfonated lignin; and the cellulose particles are selected from at least one of cellulose microcrystals and nanocellulose.

5. A method for recycling skim latex based on a process for preparing artificial latex according to claim 4, characterized in that: In step (1)-②, the centrifugal speed is 5000-10000 rpm, and the filtration adopts a 200-400 mesh filter.

6. A method for recycling skim latex based on the preparation process of artificial latex according to claim 5, characterized in that: In step (2)-①, the skim latex treatment liquid is first mixed with deionized water in a mass ratio of 1:1 to form a skim latex treatment aqueous solution, and the skim latex treatment aqueous solution is then mixed with a fresh emulsifier to form a composite skim latex aqueous solution. The composite skim latex aqueous solution is used for rubber latex emulsification operation, and then subjected to normal pressure distillation, reduced pressure distillation, and centrifugal concentration operations to prepare a high-concentration artificial latex.

7. The method for recycling skim latex based on the preparation process of artificial latex according to claim 6, characterized in that: In step (2)-①, the mass ratio of the skim latex treatment liquid used in the preparation process of the composite skim latex liquid or the composite skim latex aqueous solution is 10-100% of the skim latex treatment liquid obtained after the treatment in step (1); the fresh emulsifier includes a main emulsifier, an auxiliary emulsifier and a stabilizer in a mass ratio of 2:3:1; the main emulsifier accounts for 2-5% of the mass of the composite skim latex liquid or the composite skim latex aqueous solution; the main emulsifier is sodium dodecylbenzene sulfonate, the auxiliary emulsifier is potassium disproportionate rosin acid, and the stabilizer is Tween 80.

8. The method for recycling skim latex based on the preparation process of artificial latex according to claim 7, characterized in that: In step (2)-②, the step of preparing high-concentration artificial latex specifically includes: S1. Emulsification of rubber glue: emulsifying the rubber glue and the compound glue serum or the compound glue serum aqueous solution at a mass ratio of 1:

1. The specific operation steps are as follows: at room temperature, firstly adding a part of the compound glue serum or the compound glue serum aqueous solution to the rubber glue, stirring at a speed of 400-500r / min for 30-60min to form an oil-in-water pre-emulsified glue; then adding the remaining compound glue serum or the compound glue serum aqueous solution to the above-mentioned oil-in-water pre-emulsified liquid, using a shear emulsification method, emulsifying at a shear speed of 3000-4000rpm for 3-5min; subsequently increasing the shearing machine speed within the range of 4000-5000rpm, shearing homogenization for 5-10min, to form a stable water-in-oil crude emulsion; S2, continuous distillation: when hexane is used as the solvent, atmospheric distillation is first performed, the distillation temperature is 70-72°C, the average residence time is 6-8h, 80-90% of the total amount of solvent is removed, and then vacuum distillation is performed, and it is maintained at 80°C and 60KPa for 1h to remove the residual solvent to obtain a dilute emulsion; when pentane is used as the solvent, the distillation temperature is 45-50°C, the average residence time is 7-9h, 80-90% of the total amount of solvent is removed, and then vacuum distillation is performed, and it is maintained at 60°C and 60KPa for 1h to remove the residual solvent to obtain a dilute emulsion; S3, centrifugal concentration: the dilute emulsion is placed in a high-speed centrifuge, the speed is set to 6000-10000rpm, the centrifugal time is 5-20min, and the high-concentration artificial latex with a solid content of 50-60% is obtained by centrifugal concentration, and low-concentration skim latex is obtained at the same time.

9. The method for recycling skim latex based on the preparation process of artificial latex according to claim 8, characterized in that: In step S1, the rubber types used in the rubber glue include but are not limited to polyisoprene rubber, polybutadiene rubber, and styrene-butadiene rubber, with a number average molecular weight of 50,000-800,000. The rubber glue is obtained by dissolving a rubber block in a solvent, or directly obtained by polymerizing a rubber monomer in a solvent. The solvent is selected from one or more of C5-C9 straight-chain alkanes, C5-C9 cycloalkanes, and benzene. The mass concentration of rubber in the rubber glue is between 2-15%.

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