Method for preparing rubber grafted rubber powder based on artificial latex

Abstract

The invention provides a method for preparing rubber grafted rubber powder based on artificial latex and application of the prepared rubber grafted rubber powder to preparation of ABS (acrylonitrile-butadiene-styrene) resin by blending, and belongs to the technical field of high polymer material synthesis. On the basis of solution polymerization rubber, large-particle-size latex is directly prepared through the steps of sol preparation, emulsification and solvent removal, and then the large-particle-size latex is subjected to a monomer free radical grafting reaction to form rubber grafted rubber powder; the rubber component of the rubber grafted rubber powder has the characteristics of accurate structure design, low gel content, molecular weight and narrow distribution; the preparation method of the rubber grafted rubber powder is different from the current continuous bulk polymerization method and emulsion grafting blending method process route, and has the advantages that the rubber gel content is low, and the steric regularity of solution polymerized rubber is higher than that of free radical emulsion polymerized rubber, and the prepared rubber grafted rubber powder can be applied to preparation of toughening resin such as ABS resin and the like, and has wide application prospects. And the practicability is high.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer material synthesis, and particularly relates to a method for preparing rubber grafted rubber powder based on artificial latex. Background Art

[0002] ABS resin is a kind of high-performance rubber toughened resin, and the structure and particle size of the rubber phase have a decisive influence on the impact resistance of the resin. At present, the mainstream production technologies of industrialized ABS resin mainly include continuous bulk polymerization method and emulsion graft polymerization blending method.

[0003] The steps for preparing ABS toughened resin by continuous bulk polymerization method include: dissolving solution polymerized rubber in monomers such as styrene and acrylonitrile and a small amount of solvent, and carrying out rubber phase grafting reaction and formation of SAN resin through free radical polymerization, so as to realize one-step preparation of toughened resin. In the toughened resin prepared by this method, the copolymer formed by graft monomers styrene and acrylonitrile is the continuous phase, and the grafted rubber phase is in the form of dispersed particles. There is no participation of water and emulsifier in the reaction process. The continuous bulk method uses solution polymerized rubber, and its rubber phase structure, polymerization process and polymerization equipment will directly affect the morphology of rubber phase particles and monomer grafting condition in the resin, and then affect the performance of ABS resin. Domestic bulk ABS resin manufacturers, such as Gaoqiao Petrochemical, Huajin Shuangxing and other enterprises, use plug flow continuous tubular reactors for production. Chinese Patent ZL201210563643.8 reports the use of a plug flow flexible device and production process for the preparation of bulk ABS resin or SAN resin; Chinese Patent ZL201210566284.1 reports a tubular plug flow reactor with material internal circulation for the preparation of bulk method ABS resin. Although the process for preparing ABS resin by bulk method is short, the equipment requirements are high. Solution polymerized rubber is mostly polybutadiene or styrene-butadiene rubber. Due to the requirement of equipment system viscosity, the rubber content in the resin is limited, and it is very difficult to prepare ABS resin with a rubber content exceeding 12%.

[0004] The emulsion grafting blending method is another mainstream preparation method for ABS toughening resin. Both Daqing Petrochemical General Factory and Jilin Chemical Industry Resin Factory in China adopt this method to produce ABS resin. This process prepares large-particle-size latex through monomer emulsion polymerization, then synthesizes rubber grafted rubber powder through monomer free radical grafting reaction of rubber latex, and finally melts and extrudes the rubber grafted rubber powder and SAN resin to prepare ABS resin. Among them, the preparation of large-particle-size latex by emulsion polymerization method is the key step, which requires first synthesizing small-particle-size rubber latex, and then preparing large-particle-size rubber latex through agglomeration method or seed method. As reported in Chinese Patent CN201210380690.9, polystyrene-butadiene-isoprene integrated latex is prepared by free radical emulsion polymerization method, and then rubber grafted rubber powder is synthesized through grafting reaction; Chinese Patent CN202111307519.0 reports the preparation of polybutadiene latex with large-particle-size rubber latex by agglomeration method, and then rubber grafted rubber powder is synthesized through grafting reaction. The above reports all adopt free radical emulsion polymerization method to prepare latex, in which the gel content of the rubber phase is relatively high, between 45-60%. The emulsion blending method can blend a higher proportion of rubber powder to prepare ABS resin with a high rubber content. However, the process of preparing large-particle-size latex in the initial step is complex, and the high rubber gel content in the latex directly affects the grafting rate.

[0005] Therefore, developing a new preparation method for rubber grafted rubber powder and applying it to the preparation of toughening resins such as ABS resin is very important for innovating the ABS preparation method and expanding the variety of ABS resin. Summary of the Invention

[0006] In view of some deficiencies in the prior art, the present invention provides a method for preparing rubber grafted rubber powder based on synthetic latex, and uses the prepared rubber grafted rubber powder for blending to prepare ABS resin; the present invention directly prepares large-particle-size latex through sol, emulsification and desolventization steps based on solution polymerization rubber, and then forms rubber grafted rubber powder through monomer free radical grafting reaction of the large-particle-size latex; the rubber grafted rubber powder has precise design of rubber structure, low gel content, molecular weight and narrow distribution characteristics; the preparation method of the rubber grafted rubber powder is different from the current continuous bulk polymerization method and emulsion grafting blending process route, and it has the advantages of low rubber gel content and stronger stereoregularity of solution polymerized rubber than free radical emulsion polymerized rubber. The prepared rubber grafted rubber powder can be applied to the preparation of toughening resins such as ABS resin, and has good practicability.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention first provides a method for preparing rubber grafted rubber powder based on synthetic latex, the method comprising: The rubber latex obtained by solution polymerization is emulsified and the solvent is removed by distillation to obtain a rubber emulsion. Then, the rubber emulsion and the graft monomers are subjected to a free radical polymerization reaction to achieve monomer grafting of the rubber emulsion. Finally, gel treatment is carried out to obtain rubber grafted powder based on synthetic latex. The graft monomers include one or more of styrene, acrylonitrile, acrylate, and methacrylate.

[0008] Preferably, the graft monomers are preferably a combination of styrene and acrylonitrile.

[0009] Preferably, the method for the rubber grafted powder includes: (1) Preparation of synthetic latex emulsion: The main emulsifier and stabilizer are added to water, stirred until evenly mixed, and the pH value is adjusted to obtain an aqueous emulsifier solution. A certain amount of the aqueous emulsifier solution is slowly added to the rubber latex under shearing operation to carry out the first shear emulsification pretreatment process. After the treatment, a water-in-oil pre-emulsified latex is formed. Then, the remaining aqueous emulsifier solution is continuously and slowly added to the pre-emulsified latex under shearing operation for the second shear treatment and kept shearing for a certain time. After the treatment, a stable oil-in-water coarse emulsion is formed, and the residual organic solvents present in the oil-in-water coarse emulsion are removed to obtain a synthetic latex emulsion. (2) Preparation of graft emulsion: The synthetic latex emulsion, graft monomers, activator, and regulator are added to a reactor for an initial graft reaction. After a certain time, an aqueous emulsifier solution, the remaining graft monomers, regulator, and initiator are added in a continuous feeding manner to continue the grafting process. After the feeding ends after a certain time, the remaining activator is added for aging treatment. After the graft reaction ends, an antioxidant emulsion and a whitening agent solution are added, and the temperature is lowered to complete the graft polymerization operation to obtain a graft emulsion. (3) Under stirring conditions, a certain amount of dilute sulfuric acid is added to the graft emulsion for demulsification and ripening treatment, and then it is filtered, washed, and dried to obtain rubber grafted powder.

[0010] Preferably, in step (1), in the aqueous emulsifier solution, the mass ratio of the main emulsifier to the stabilizer is 2 - 4:1; the main emulsifier accounts for 2% to 5% of the total mass of the aqueous emulsifier solution; The main emulsifier includes one or more mixtures of anionic surfactants or non-ionic surfactants; The stabilizer includes one or more mixtures of Span 20, 60, or 80 and Tween 20, 60, or 80; During the preparation of the aqueous emulsifier solution, it is heated and stirred at 50 - 60 °C for 4 - 8 h, and then the pH value is adjusted to 9 - 12.

[0011] Preferably, the anionic surfactant includes one or more mixtures of benzenesulfonate, disproportionated rosin acid soap, naphthalenesulfonate, fatty acid salt, oleic acid soap; The nonionic surfactant includes one or more mixtures of fatty alcohol polyoxyethylene ether, fatty amine polyoxyethylene ether, alkylphenol polyoxyethylene ether, and sorbitan oleate; wherein, the carbon number of the alkyl is between 6 and 22; Preferably, in step (1), the mass ratio of the rubber latex to the total amount of the two emulsifier aqueous solutions is 1:1; the mass concentration of rubber in the rubber latex is 2-30%; The rubber in the rubber latex includes rare earth or anionic solution-polymerized polyisoprene rubber, polybutadiene rubber or styrene-butadiene rubber, with a number average molecular weight of 50,000-800,000; the latex is obtained by dissolving solution-polymerized rubber blocks or is a rubber latex obtained by polymerizing monomers in a solvent; The solvent includes one or more of C5-C9 straight-chain alkanes, C5-C9 cycloalkanes, and benzene.

[0012] Preferably, in step (1), the steps of the first shearing treatment are: shearing at room temperature and a rotation speed of 400-500 r / min for 30-60 min; The steps of the second shearing are: shearing and emulsifying at 3000-4000 rpm for 3-5 min, and then shearing and homogenizing at 4000-5000 rpm for 5-10 min; The step of removing the residual organic solvent present in the water-in-oil crude emulsion includes: atmospheric distillation, vacuum distillation, or a combination of atmospheric distillation and vacuum distillation, and the solvent removal can be carried out by an intermittent method or a continuous method; The atmospheric distillation is carried out at 45-82 °C under atmospheric pressure for 6-9 h; The vacuum distillation is carried out at 60-80 °C and 60 KPa under reduced pressure, and maintained for 1-1.5 h after the vacuum degree is stabilized.

[0013] Preferably, in step (2), the mass concentration of the synthetic rubber latex is 20-35%, and it is prepared by adding demineralized water after removing the residual organic solvent; The activator is a redox initiation system, including: glucose, sodium pyrophosphate, ferrous sulfate; the activator also includes cumene hydroperoxide or tert-butyl cumene hydroperoxide; The regulator is one or a mixture of alkyl mercaptan and sodium dimethyldithiocarbamate; The antioxidant emulsion includes potassium disproportionated rosin, demineralized water, antioxidant PS-800 (dialkyl thiodipropionate), and hindered phenolic antioxidant I-245; The brightening agent solution is prepared from EDTA, sodium formaldehyde sulfoxylate and demineralized water.

[0014] Preferably, in step (2), the mass ratio of the graft monomer to the rubber in the synthetic latex emulsion is 1-2:4; The mass ratio of the activator, dodecyl mercaptan and the brightening agent solution to the synthetic latex emulsion is 0.2-1:0.2-1:0.5-3:100; The mass ratio of the antioxidant emulsion to the rubber in the synthetic latex emulsion is 0.1-1:100.

[0015] Preferably, in step (2), the initial graft reaction is: reacting at 40-60 °C for 0.5-2 h, and after the reaction is completed, heating up to 60-70 °C for continuous feeding; After the continuous feeding is completed, heating up to above 70 °C for continuous feeding for 1-3 h; The reaction time of the aging treatment is 20 min.

[0016] Preferably, in step (3), the volume ratio of the graft emulsion to the dilute sulfuric acid is 100:0.1-1; The conditions for demulsification and ripening are demulsification and ripening at 90 °C for 10 min.

[0017] The present invention also provides a rubber grafted powder prepared by the above method.

[0018] The present invention also provides the use of the above rubber grafted powder in the preparation of ABS resin or in increasing the rubber content of ABS resin.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention uses a solution-polymerized polyisoprene rubber, butadiene rubber or styrene-butadiene rubber rubber solution. Through emulsification and solvent removal by distillation operations, a large-particle-size rubber emulsion is directly obtained. Then, through a free radical polymerization reaction with a graft monomer, the monomer grafting process of the rubber emulsion is realized, which is different from the conventional bulk method and emulsion polymerization-grafting method-blending process for preparing ABS. Compared with the process for preparing ABS by the bulk method, the method of the present invention can prepare an ABS resin with a high rubber content, and the molecular structure of the solution-polymerized rubber used can be precisely designed. Compared with the conventional emulsion polymerization-grafting-blending method for preparing ABS, the method of the present invention directly emulsifies the solution-polymerized rubber solution to prepare a large-particle-size latex, without the monomer free radical emulsion polymerization process, nor the complex process of aggregating small-particle-size latex or seed polymerization to prepare large-particle-size latex. At the same time, the rubber gel content in the latex is low and the grafting rate is high, which is beneficial to improving the impact performance of the rubber powder. Description of the Drawings

[0020] Figure 1For the latex particle size (a) prepared in Example 1, and the F-t curve (b), morphology (c), and fracture cross-section diagram (d) of the ABS toughening resin prepared therefrom.

[0021] Figure 2 For the effects of the agglomerating agent (a) and agglomeration time (b) in Comparative Example 1 on the latex particle size during the agglomeration process.

[0022] Figure 3 For the scanning electron microscopy morphology diagram of the large-particle-size integrated latex prepared in Comparative Example 2. Detailed implementation manners

[0023] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited thereto.

[0024] Example 1: S1. Preparation of artificial latex emulsion: S11. Preparation of polyisoprene rubber solution and emulsifier aqueous solution: 18 g of polyisoprene rubber was added to 182 g of hexane, and stirred at 40 °C for 10 h to prepare a polyisoprene rubber solution with a mass ratio of 8%, and reserved; 2 g of sodium dodecylbenzenesulfonate, 6 g of potassium disproportionated rosinate, and 2 g of Tween 80 were added to 190 g of deionized water, stirred at 50 °C for 4 h, and the pH value was adjusted to 10 with KOH to obtain an emulsifier aqueous solution, and reserved.

[0025] S12. Preparation of artificial latex emulsion: At room temperature, emulsification was carried out according to the mass ratio of emulsifier aqueous solution to polyisoprene rubber solution of 1:1. The emulsification steps were as follows: First, 1 / 3 of the emulsifier aqueous solution was added to the polyisoprene rubber solution, and shear emulsification was carried out at a rotation speed of 400 r / min for 30 min to form a water-in-oil pre-emulsion; then, at a shear rotation speed of 3000 rpm, the remaining emulsifier aqueous solution was slowly added to the pre-emulsion, and after the addition was completed, shear emulsification was carried out for 3 min; the shear rotation speed was increased to 4000 rpm, and shear homogenization was continued for 5 min to form a stable oil-in-water coarse emulsion.

[0026] The above-mentioned oil-in-water coarse emulsion was distilled at normal pressure at 45 °C for 7 h to remove 80% of the total amount of hexane; then, at 80 °C and 60 KPa, vacuum distillation was carried out for 1 h to remove the residual solvent, and then it was formulated with demineralized water to obtain an artificial latex emulsion with a mass concentration of 30%.

[0027] S2. Preparation of grafted emulsion: Using the above artificial latex emulsion as the raw material, free radical latex grafting reaction was carried out according to the following formula, and the specific steps are shown as follows: Add 60 g of synthetic latex emulsion, 1.5 g of acrylonitrile, 4.5 g of styrene, and 0.08 g of dodecyl mercaptan into the reaction kettle, stir and heat up. After the temperature reaches 43 °C, add 0.06 g of the regulator sodium dimethyldithiocarbamate and the activator composed of 0.18 g of glucose, 0.15 g of sodium pyrophosphate, 0.003 g of ferrous sulfate, and 0.06 g of cumene hydroperoxide. Then continue to heat up to 55 °C and react for 55 minutes. After the reaction is completed, heat up to 65 °C and start continuous feeding. Feed 3.5 g of acrylonitrile, 11.5 g of styrene, 0.6 g of dodecyl mercaptan, 0.1 g of cumene hydroperoxide, 2 g of potassium disproportionated rosin, and 9 g of demineralized water into the reaction kettle. The feeding time is 110 minutes.

[0028] After the continuous feeding is completed, heat up the reaction kettle to 71 °C, and supplement an appropriate amount of regulator and activator. The supplementary amounts are 0.03 g of sodium dimethyldithiocarbamate, 0.09 g of glucose, 0.07 g of sodium pyrophosphate, 0.0015 g of ferrous sulfate, and 0.03 g of cumene hydroperoxide. After the supplementation, keep warm for 20 minutes to allow the unreacted monomers to fully react. Then add the antioxidant emulsion and the brightening agent solution to obtain the grafted emulsion.

[0029] Among them, the antioxidant emulsion is composed of 1.3 g of potassium disproportionated rosin (12%), 1.5 g of demineralized water, 0.25 g of PS-800, and 0.25 g of I-245. The brightening agent solution is composed of 0.07 g of EDTA, 0.07 g of sodium formaldehyde sulfoxylate, and 1.4 g of demineralized water.

[0030] S3. Preparation of rubber-grafted rubber powder: Cool down and discharge the grafted emulsion, and obtain the rubber-grafted rubber powder after coagulation, washing, dehydration, and drying.

[0031] S4. Preparation of ABS toughened resin: Weigh 24 parts by mass of the rubber-grafted rubber powder powder and 76 parts of SAN resin for blending and granulation to obtain the ABS toughened resin.

[0032] The properties of the prepared ABS resin are as follows: the Izod notched impact property of the ABS resin is 128 J / m, the tensile strength is 48.3 MPa, the melt flow rate is 2.60 g / min, the elongation at break is 32.6%, the flexural strength is 58.0 MPa, the flexural modulus is 2066 MPa, and the Rockwell hardness is 120.

[0033] Figure 1 For the prepared latex particle size (a) and the F-t curve (b), morphology (c), and fracture cross-section diagram (d) of the prepared ABS toughened resin, it can be seen from the figure that the prepared isoprene latex is a large-particle-size latex, and the primary curve and cross-section conform to the characteristics of the toughened resin, indicating that the ABS toughened resin has been successfully prepared.

[0034] Example 2: S1. Preparation of artificial latex emulsion: S11. Preparation of lithium-based anionic solution-polymerized styrene-butadiene rubber solution and aqueous emulsifier solution: Add 18 g of lithium-based anionic solution-polymerized styrene-butadiene rubber to 182 g of hexane, stir at 40 °C for 10 h to prepare a lithium-based anionic solution-polymerized styrene-butadiene rubber solution with a mass ratio of 8%, and set aside; add 2 g of sodium dodecylbenzenesulfonate, 6 g of non-ionic emulsifier OP-10, and 2 g of Tween 80 to 190 g of deionized water, stir at 50 °C for 4 h, and adjust the pH value to 10 with KOH to obtain an aqueous emulsifier solution, and set aside.

[0035] S12. Preparation of artificial latex emulsion: Perform normal-temperature emulsification according to the mass ratio of 1:1 of the aqueous emulsifier solution and the lithium-based anionic solution-polymerized styrene-butadiene rubber solution. First, add 1 / 3 of the aqueous emulsifier solution to the lithium-based anionic solution-polymerized styrene-butadiene rubber solution, shear and emulsify at a rotation speed of 400 r / min for 30 min to form a water-in-oil pre-emulsion; then, at a shear rotation speed of 3000 rpm, slowly add the remaining aqueous emulsifier solution to the pre-emulsion, and continue to shear and emulsify for 3 min after adding; increase the shear rotation speed to 4000 rpm and continue to shear and homogenize for 5 min to form a stable oil-in-water coarse emulsion.

[0036] Distill the above oil-in-water coarse emulsion at 45 °C under normal pressure for 7 h to remove 80% of the total amount of hexane; then, under the conditions of 80 °C and 60 KPa, perform vacuum distillation for 1 h to remove the residual solvent, and then adjust with deionized water to obtain an artificial latex emulsion with a mass concentration of 30%.

[0037] S2. Preparation of grafted emulsion: Using the above artificial latex emulsion as raw material, perform free radical latex grafting reaction according to the following formula, and the specific steps are as follows: Add 60 g of artificial latex emulsion, 1.5 g of acrylonitrile, 4.5 g of styrene, and 0.08 g of dodecyl mercaptan to the reaction kettle and stir to raise the temperature. When the temperature reaches 43 °C, add 0.06 g of regulator sodium dimethyldithiocarbamate and an activator composed of 0.18 g of glucose, 0.15 g of sodium pyrophosphate, 0.003 g of ferrous sulfate, and 0.06 g of cumene hydroperoxide, and then continue to raise the temperature to 55 °C and react for 55 minutes. After the reaction is completed, raise the temperature to 65 °C and start continuous feeding. Feed 3.5 g of acrylonitrile, 11.5 g of styrene, 0.6 g of dodecyl mercaptan, 0.1 g of cumene hydroperoxide, 2 g of potassium disproportionated rosin acid, and 9 g of deionized water into the reaction kettle, and the feeding time is 110 minutes.

[0038] After the continuous feeding is completed, the reaction kettle is heated to 71 °C, and an appropriate amount of regulator and activator are added. The added amounts are 0.03 g of sodium dimethyldithiocarbamate, 0.09 g of glucose, 0.07 g of sodium pyrophosphate, 0.0015 g of ferrous sulfate, and 0.03 g of cumene hydroperoxide. After the addition, keep warm for 20 minutes to allow the unreacted monomers to fully react, and then add the antioxidant emulsion and the brightening agent solution to obtain the grafted emulsion.

[0039] Among them, the antioxidant emulsion consists of 1.3 g of potassium disproportionated rosin (12%), 1.5 g of demineralized water, 0.25 g of PS-800, and 0.25 g of I-245. The brightening agent solution consists of 0.07 g of EDTA, 0.07 g of sodium formaldehyde sulfoxylate, and 1.4 g of demineralized water.

[0040] S3. Preparation of rubber-grafted rubber powder: Cool and discharge the grafted emulsion, and obtain rubber-grafted rubber powder after coagulation, washing, dehydration, and drying.

[0041] S4. Preparation of ABS toughened resin: Weigh 24 parts by mass of the rubber-grafted rubber powder and 76 parts of SAN resin for blending and granulation to obtain the ABS toughened resin.

[0042] The properties of the prepared ABS resin are as follows: the Izod notched impact property of the ABS resin is 122 J / m, the tensile strength is 54.4 MPa, the melt flow rate is 2.06 g / min, the elongation at break is 18.8%, the flexural strength is 53.4 MPa, the flexural modulus is 2136 MPa, and the Rockwell hardness is 121.

[0043] Example 3: S1. Preparation of synthetic rubber latex emulsion: S11. Preparation of rare earth polyisoprene rubber solution and aqueous emulsifier solution: Add 18 g of rare earth polyisoprene rubber to 182 g of hexane, stir at 40 °C for 10 h to prepare a 8% rare earth polyisoprene rubber solution for standby; add 4 g of sodium oleate, 6 g of potassium disproportionated rosin, 2 g of sodium dodecylbenzenesulfonate, and 4 g of Tween 80 to 184 g of deionized water, stir at 50 °C for 4 h, and adjust the pH value to 10 with KOH to obtain the aqueous emulsifier solution for standby.

[0044] S12. Preparation of synthetic rubber latex emulsion: At room temperature, emulsify according to the mass ratio of 1:1 of the emulsifier aqueous solution and the rare earth polyisoprene rubber latex. First, add 1 / 3 of the emulsifier aqueous solution to the rare earth polyisoprene rubber latex, and shear and emulsify at a rotation speed of 400 r / min for 30 min to form a water-in-oil pre-emulsified latex; then, at a shear speed of 3000 rpm, slowly add the remaining emulsifier aqueous solution to the pre-emulsified latex. After the addition is completed, continue to shear and emulsify for 3 min; increase the shear speed to 4000 rpm and continue to shear and homogenize for 5 min to form a stable oil-in-water coarse emulsion.

[0045] Distill the above oil-in-water coarse emulsion at 45 °C under normal pressure for 7 h to remove 80% of the total amount of hexane; then, under the conditions of 80 °C and 60 KPa, carry out vacuum distillation for 1 h to remove the residual solvent, and then adjust with demineralized water to obtain an artificial latex emulsion with a mass concentration of 30%.

[0046] S2. Preparation of grafted emulsion: Using the above artificial latex emulsion as the raw material, carry out a free radical latex grafting reaction according to the following formula. The specific steps are as follows: Add 60 g of artificial latex emulsion, 1.5 g of acrylonitrile, 4.5 g of styrene and 0.08 g of dodecyl mercaptan to the reaction kettle and stir to raise the temperature. When the temperature reaches 43 °C, add 0.06 g of the regulator sodium dimethyldithiocarbamate and the activator composed of 0.18 g of glucose, 0.15 g of sodium pyrophosphate, 0.003 g of ferrous sulfate and 0.06 g of cumene hydroperoxide, and then continue to raise the temperature to 55 °C and react for 55 minutes. After the reaction is completed, raise the temperature to 65 °C and start continuous feeding. Feed 3.5 g of acrylonitrile, 11.5 g of styrene, 0.6 g of dodecyl mercaptan, 0.1 g of cumene hydroperoxide, 2 g of potassium disproportionated rosin and 9 g of demineralized water into the reaction kettle, and the feeding time is 110 minutes.

[0047] After the continuous feeding is completed, raise the temperature of the reaction kettle to 71 °C, and supplement an appropriate amount of regulator and activator. The supplementary amounts are 0.09 g of glucose, 0.07 g of sodium pyrophosphate, 0.0015 g of ferrous sulfate, 0.03 g of sodium dimethyldithiocarbamate, 0.03 g of cumene hydroperoxide. After the supplementation is completed, keep warm for 20 minutes to make the unreacted monomers fully react, and then add antioxidant and brightening agent to obtain the grafted emulsion.

[0048] Among them, the composition of the antioxidant emulsion is 1.3 g of potassium disproportionated rosin (12%), 1.5 g of demineralized water, 0.25 g of PS-800 and 0.25 g of I-245, and the composition of the brightening agent solution is 0.07 g of EDTA, 0.07 g of sodium formaldehyde sulfoxylate and 1.4 g of demineralized water.

[0049] S3. Preparation of rubber grafted rubber powder: The grafted emulsion is cooled and discharged, and after coagulation, washing, dehydration, and drying, rubber grafted rubber powder is obtained.

[0050] S4. Preparation of ABS toughened resin: Weigh 24 parts by mass of rubber grafted rubber powder and 76 parts of SAN resin for blending and granulation to obtain ABS toughened resin.

[0051] The properties of the prepared ABS resin are as follows: The Izod notched impact property of the ABS resin is 113 J / m, the tensile strength is 46.8 MPa, the melt flow rate is 2.56 g / min, the elongation at break is 31.6%, the flexural strength is 53.4 MPa, the flexural modulus is 2050 MPa, and the Rockwell hardness is 121.

[0052] Example 4: S1. Preparation of synthetic rubber latex emulsion: S11. Preparation of rare earth polyisoprene rubber solution and aqueous emulsifier solution: Add 18 g of rare earth polyisoprene rubber to 182 g of hexane, stir at 40 °C for 10 h to prepare a 8% rare earth polyisoprene rubber solution by mass, and set aside; add 4 g of sodium stearate, 8 g of sodium dodecylbenzenesulfonate, and 4 g of Tween 80 to 184 g of deionized water, stir at 50 °C for 4 h, and adjust the pH value to 10 with KOH to obtain an aqueous emulsifier solution, and set aside.

[0053] S12. Preparation of synthetic rubber latex emulsion: Perform normal temperature emulsification according to the mass ratio of 1:1 of the aqueous emulsifier solution and the rare earth polyisoprene rubber solution. First, add 1 / 3 of the aqueous emulsifier solution to the rare earth polyisoprene rubber solution, shear emulsify at a speed of 400 r / min for 30 min to form a water-in-oil pre-emulsified rubber solution; then, at a shear speed of 3000 rpm, slowly add the remaining aqueous emulsifier solution to the pre-emulsified rubber solution, and continue to shear emulsify for 3 min after adding; increase the shear speed to 4000 rpm and continue to shear emulsify and homogenize for 5 min to form a stable oil-in-water coarse emulsion.

[0054] The above oil-in-water coarse emulsion is distilled at normal pressure for 7 h at 45 °C to remove 80% of the total amount of hexane; then, at 80 °C and 60 KPa, it is distilled under reduced pressure for 1 h to remove the residual solvent, and then formulated with demineralized water to obtain a synthetic rubber latex emulsion with a mass concentration of 30%.

[0055] S2. Preparation of grafted emulsion: Using the above synthetic rubber latex emulsion as the raw material, carry out free radical latex grafting reaction according to the following formula, and the specific steps are as follows: Add 60 g of artificial latex emulsion, 1.5 g of acrylonitrile, 4.5 g of styrene and 0.08 g of dodecyl mercaptan to the reaction kettle and stir to raise the temperature. After the temperature reaches 43 °C, add 0.06 g of the regulator sodium dimethyldithiocarbamate and the activator composed of 0.18 g of glucose, 0.15 g of sodium pyrophosphate, 0.003 g of ferrous sulfate and 0.06 g of cumene hydroperoxide. Then continue to raise the temperature to 55 °C and react for 55 minutes. After the reaction is completed, raise the temperature to 65 °C and start continuous feeding. Feed 3.5 g of acrylonitrile, 11.5 g of styrene, 0.6 g of dodecyl mercaptan, 0.1 g of cumene hydroperoxide, 2 g of potassium disproportionated rosin and 9 g of demineralized water into the reaction kettle. The feeding time is 110 minutes.

[0056] After the continuous feeding is completed, raise the temperature of the reaction kettle to 71 °C and add an appropriate amount of activator. The added amounts are 0.09 g of glucose, 0.07 g of sodium pyrophosphate, 0.0015 g of ferrous sulfate, 0.03 g of sodium dimethyldithiocarbamate, 0.03 g of cumene hydroperoxide. After the addition, keep warm for 20 minutes to allow the unreacted monomers to react fully. Then add the antioxidant emulsion and the brightening agent solution to obtain the grafted emulsion.

[0057] Among them, the antioxidant emulsion is composed of 1.3 g of potassium disproportionated rosin (12%), 1.5 g of demineralized water, 0.25 g of PS-800 and 0.25 g of I-245. The brightening agent solution is composed of 0.07 g of EDTA, 0.07 g of sodium formaldehyde sulfoxylate and 1.4 g of demineralized water.

[0058] S3. Preparation of rubber-grafted rubber powder: Cool and discharge the grafted emulsion, and obtain the rubber-grafted rubber powder after coagulation, washing, dehydration and drying.

[0059] S4. Preparation of ABS toughened resin: Weigh 24 parts by mass of the rubber-grafted rubber powder powder and 76 parts of SAN resin for blending and pelletizing to obtain the ABS toughened resin.

[0060] The properties of the prepared ABS resin are as follows: the Izod notched impact property of the ABS resin is 106 J / m, the tensile strength is 56.3 MPa, the melt flow rate is 1.75 g / min, the elongation at break is 17.8%, the flexural strength is 53.4 MPa, the flexural modulus is 2200 MPa, and the Rockwell hardness is 120.

[0061] Comparative Example 1: In this comparative example, the agglomeration method was used to prepare large-particle-size latex. The specific steps were as follows: 1000 g of deionized water, 21 g of potassium disproportionated rosin, 0.36 g of potassium hydroxide, 1.8 g of potassium chloride, 3.5 g of tert-dodecyl mercaptan, 1.5 g of potassium persulfate, and 120 g of styrene were added to a 2 L polymerization kettle. After purging with nitrogen three times, 480 g of butadiene was added. The polymerization kettle was started to stir, pre-emulsified for 20 minutes, and then the temperature was raised. When the temperature reached 65 °C, the timing started. After reacting for 11 hours, the temperature was lowered, and the material was discharged at 50 °C to obtain small-particle-size integrated latex with an average particle size of about 100 nm.

[0062] 6 g of the polymer agglomerating agent emulsion was added to the above-mentioned small-particle-size integrated latex, and stirred at room temperature for 30 minutes to obtain large-particle-size integrated latex with an average particle size of about 360 nm.

[0063] Latex monomer grafting reaction: 600 g of large-particle-size integrated latex, 75 g of styrene, 25 g of acrylonitrile, and 1.8 g of dodecyl mercaptan were added to a 2 L reaction kettle. The temperature was raised. When the temperature reached 43 °C, 0.6 g of sodium dimethyldithiocarbamate as a regulator was added. The activator (1.8 g of glucose, 1.5 g of sodium pyrophosphate, 0.03 g of ferrous sulfate, and 0.6 g of cumene hydroperoxide) was added, and the temperature was continuously raised to 55 °C. After reacting for 55 minutes, the temperature was raised to 65 °C, and continuous feeding started. The feed was 75 g of acrylonitrile, 225 g of styrene, 1.3 g of dodecyl mercaptan, 2 g of cumene hydroperoxide, 30 g of potassium disproportionated rosin, and 90 g of deionized water. The feeding time was 110 minutes. After the continuous feeding was completed, the temperature was raised to 71 °C, and 0.3 g of sodium dimethyldithiocarbamate as a regulator was added, and the activator (0.9 g of glucose, 0.7 g of sodium pyrophosphate, 0.015 g of ferrous sulfate, and 0.3 g of cumene hydroperoxide) was added and continued for 20 minutes to make the unreacted monomers fully react. Thereafter, an antioxidant and a brightening agent were added, the temperature was lowered and the material was discharged. After coagulation, washing, dehydration, and drying, ABS grafted powder was obtained.

[0064] Figure 2 For the effects of the agglomerating agent (a) and the agglomeration time (b) in Comparative Example 1 on the particle size of the prepared latex, it can be seen from the figure that the preparation of large-particle-size latex with a polymer agglomerating agent is a changing process, and the whole process tends to be stable when the agglomeration time reaches 30 minutes.

[0065] Table 1. Changes in latex particle size and gel (3 batches) before and after agglomeration in Comparative Example 1 It can be seen from Table 1 that the average particle size of the latex increased from 110 nm to 340 nm before and after agglomeration, and the polymer agglomeration process has strong stability.

[0066] Comparative Example 2: Add 1000 g of deionized water, 21 g of potassium disproportionated rosin, 0.36 g of potassium hydroxide, 1.8 g of potassium chloride, 3.5 g of tert-dodecyl mercaptan, and 1.5 g of potassium persulfate into a 2 L polymerization kettle. After purging with nitrogen three times, add 600 g of butadiene. Start the stirring of the polymerization kettle and pre-emulsify for 20 minutes. Then start heating. When the temperature reaches 65 °C, start timing. After reacting for 11 hours, cool down the temperature and discharge the material at 50 °C to obtain small-particle-size integrated latex with an average particle size of about 100 nm.

[0067] Add 100 g of the above-mentioned small-particle-size integrated latex, 800 g of refined water, 16 g of potassium disproportionated rosin, 0.23 g of potassium hydroxide, 1.1 g of potassium chloride, 2.5 g of tert-dodecyl mercaptan, and 0.9 g of potassium persulfate into a 2 L polymerization kettle. After purging with nitrogen three times, evacuate the air. Stir at a speed of 200 rpm, add 480 g of butadiene, and pre-emulsify for 20 minutes. Control the temperature of the reaction kettle at 60 - 85 °C and the reaction time at 32 hours. The final reaction conversion rate reaches over 90%. During the reaction process, add a certain amount of initiator and emulsifier to obtain large-particle-size integrated latex with an average particle size of about 400 nm.

[0068] Latex monomer grafting reaction: Add 600 g of the above-mentioned large-particle-size integrated latex, 75 g of styrene, 25 g of acrylonitrile, and 1.8 g of dodecyl mercaptan into a 2 L reaction kettle. Heat up the temperature. When the temperature reaches 43 °C, add 0.6 g of sodium dimethyldithiocarbamate as a regulator. Add the activator (1.8 g of glucose, 1.5 g of sodium pyrophosphate, 0.03 g of ferrous sulfate, and 0.6 g of cumene hydroperoxide) and continue heating up to 55 °C. After reacting for 55 minutes, heat up to 65 °C and start continuous feeding. The feed is 75 g of acrylonitrile, 225 g of styrene, 1.3 g of dodecyl mercaptan, 2 g of cumene hydroperoxide, 30 g of potassium disproportionated rosin, and 90 g of deionized water. The feeding time is 110 minutes. After the continuous feeding is completed, heat up to 71 °C and add an additional 0.3 g of sodium dimethyldithiocarbamate as a regulator and the activator (0.9 g of glucose, 0.7 g of sodium pyrophosphate, 0.015 g of ferrous sulfate, and 0.3 g of cumene hydroperoxide) for 20 minutes to make the unreacted monomers fully react. Then add antioxidants and brighteners, cool down the temperature and discharge the material. After coagulation, washing, dehydration, and drying, obtain ABS grafted powder.

[0069] Figure 3 It is the scanning electron microscope morphology diagram of the large-particle-size integrated latex prepared in Comparative Example 2. It can be seen from the figure that the average particle size of the large-particle-size latex prepared by the seed method is uniform.

[0070] Table 2. Particle size changes and gels of the seed latex and large-particle-size latex in Comparative Example 2 As can be seen from Table 2, for the large-particle-size latex prepared by the seed method, the average particle size is about 470 nm, and the gel content is greater than 60%.

[0071] Table 3. Grafting ratio and grafting efficiency of rubber-grafted rubber powder As can be seen from Table 3, due to the low gel content of artificial latex, the grafting ratio and grafting efficiency during the grafting process are higher than those of the latex prepared by the seed method or the agglomeration method.

[0072] Table 4. Performance indicators of ABS resin prepared by blending rubber-grafted rubber powder in Examples 1-4 As can be seen from Table 3 and Table 4, due to the relatively high grafting ratio and grafting efficiency of artificial latex, on the premise that the melt flow rate is relatively fixed, it has a relatively high impact strength, all exceeding 100 J / m, and the Vicat temperature is basically the same, which is basically the same as that of the conventional emulsion polymerization-grafting-blending method.

[0073] In summary, the present invention is based on solution-polymerized rubber, and large-particle-size latex is prepared through steps of sol, emulsification, and desolventization, and then the large-particle-size latex is subjected to monomer free-radical grafting reaction to form rubber-grafted rubber powder; the rubber-grafted rubber powder has precisely designed structure, low gel content, and characteristics of molecular weight and narrow distribution; the preparation method of the rubber-grafted rubber powder is different from the current continuous bulk polymerization method and emulsion grafting-blending method process routes, and the prepared rubber-grafted rubber powder can be applied to the preparation of toughened resins such as ABS resin, and has good practicability.

[0074] The above embodiments are the preferred embodiments of the present invention, but the present invention is not limited to the above embodiments. Without departing from the essence of the present invention, any obvious improvements, substitutions, or modifications that those skilled in the art can make all belong to the protection scope of the present invention.

Claims

1. A method for preparing rubber grafted rubber powder based on synthetic latex, characterized in that, The method includes: Emulsifying and removing solvents by distillation from the rubber latex obtained by solution polymerization to obtain a rubber emulsion, then subjecting the rubber emulsion and graft monomers to a free radical polymerization reaction to achieve monomer grafting of the rubber emulsion, and finally performing gel treatment to obtain rubber grafted powder based on synthetic latex; The graft monomers include one or more of styrene, acrylonitrile, acrylate, and methacrylate.

2. The method according to claim 1, wherein The method for the rubber grafted powder includes: (1) Preparation of synthetic latex emulsion: Adding a main emulsifier and a stabilizer to water, stirring until evenly mixed, and adjusting the pH value to obtain an aqueous emulsifier solution; Slowly adding a certain amount of the aqueous emulsifier solution to the rubber latex during shearing operation to perform the first shear emulsification pretreatment process, and forming a water-in-oil pre-emulsified latex after the treatment; Then, continuously and slowly adding the remaining aqueous emulsifier solution to the pre-emulsified latex during shearing operation, performing the second shear treatment and maintaining shearing for a certain time, and forming a stable oil-in-water coarse emulsion after the treatment. Removing the residual organic solvents present in the oil-in-water coarse emulsion to obtain the synthetic latex emulsion; (2) Preparation of graft emulsion: Adding the synthetic latex emulsion, graft monomers, activator, and regulator to a reactor for an initial graft reaction. After a certain time, adding the aqueous emulsifier solution, the remaining graft monomers, regulator, and initiator in a continuous feeding manner to continue the grafting process. After the feeding ends after a certain time, adding the remaining activator for aging treatment. After the graft reaction ends, adding an antioxidant emulsion and a whitening agent solution, and cooling to complete the graft polymerization operation to obtain the graft emulsion; (3) Under stirring conditions, adding a certain amount of dilute sulfuric acid to the graft emulsion for demulsification and ripening treatment, then filtering, washing, and drying to obtain the rubber grafted powder.

3. The method according to claim 2, wherein In step (1), in the aqueous emulsifier solution, the mass ratio of the main emulsifier to the stabilizer is 2 - 4:1; the main emulsifier accounts for 2% to 5% of the total mass of the aqueous emulsifier solution; The main emulsifier includes one or more mixtures of anionic surfactants or non-ionic surfactants; The stabilizer includes one or more mixtures of Span 20, 60, or 80 and Tween 20, 60, or 80; During the preparation of the aqueous emulsifier solution, heating and stirring are performed at 50 - 60 °C for 4 - 8 h, and then the pH value is adjusted to 9 - 12; The mass ratio of the rubber latex to the total amount of the two aqueous emulsifier solutions used is 1:1; the mass concentration of rubber in the rubber latex is 2% - 30%; The rubber in the rubber latex includes rare earth or anionic solution-polymerized polyisoprene rubber, polybutadiene rubber, or styrene-butadiene rubber, with a number average molecular weight of 50,000 - 800,000; the latex is obtained by dissolving solution-polymerized rubber blocks or directly polymerizing monomers in a solvent to obtain the rubber latex; The solvent includes one or more of C5 - C9 straight-chain alkanes, C5 - C9 cycloalkanes, and benzene; 4. The method according to claim 3, wherein The anionic surfactant includes one or more mixtures of benzenesulfonate, disproportionated rosin acid soap, naphthalenesulfonate, fatty acid salt, and oleic acid soap; The non-ionic surfactant includes one or a mixture of fatty alcohol polyoxyethylene ether, fatty amine polyoxyethylene ether, alkylphenol polyoxyethylene ether, and sorbitan oleate; wherein, the carbon number of the alkyl group is between 6 and 22.

5. The method according to claim 2, wherein In step (1), the steps of the first shearing treatment are: shearing at normal temperature and a rotation speed of 400 - 500 r / min for 30 - 60 min; The steps of the second shearing are: shearing and emulsifying at 3000 - 4000 rpm for 3 - 5 min, and then shearing and homogenizing at 4000 - 5000 rpm for 5 - 10 min; The steps of removing the residual organic solvent present in the water-in-oil crude emulsion include: atmospheric distillation, vacuum distillation, or a combination of atmospheric distillation and vacuum distillation; The atmospheric distillation is carried out at 45 - 82 °C under atmospheric pressure for 6 - 9 h; The vacuum distillation is carried out at 60 - 80 °C and 60 KPa under reduced pressure, and maintained for 1 - 1.5 h after the vacuum degree is stable.

6. The method according to claim 2, wherein In step (2), the mass concentration of the artificial latex emulsion is 20 - 35%, and it is prepared by adding demineralized water after removing the residual organic solvent; The activator is a redox initiation system, including: glucose, sodium pyrophosphate, ferrous sulfate; the activator also includes cumene hydroperoxide or tert-butyl cumene hydroperoxide; The regulator is one or a mixture of alkyl mercaptan and sodium dimethyldithiocarbamate; The antioxidant emulsion includes potassium disproportionated rosin, demineralized water, antioxidant dialkyl thiodipropionate, and hindered phenol antioxidant I-245; The whitening agent solution is prepared from EDTA, sodium formaldehyde sulfoxylate, and demineralized water.

7. The method according to claim 2, wherein In step (2), the mass ratio of the graft monomer to the rubber in the artificial latex emulsion is 1 - 2:4; The mass ratio of the activator, dodecyl mercaptan, and the whitening agent solution to the artificial latex emulsion is 0.2 - 1:0.2 - 1:0.5 - 3:100; The mass ratio of the antioxidant emulsion to the rubber in the artificial latex emulsion is 0.1 - 1:100; The initial graft reaction is: reacting at 40 - 60 °C for 0.5 - 2 h, and after the end of reaction 1, heating up to 60 - 70 °C for continuous feeding; After the continuous feeding ends, heating up to above 70 °C for continuous feeding for 1 - 3 h; The reaction time of the aging treatment is 20 min.

8. The method according to claim 2, wherein In step (3), the volume ratio of the graft emulsion to dilute sulfuric acid is 100:0.1 - 1; The conditions for demulsification and ripening are demulsification and ripening at 90 °C for 10 min.

9. The rubber grafted rubber powder prepared by the method for preparing rubber grafted rubber powder based on artificial latex according to any one of claims 1 - 8.

10. The application of the rubber grafted rubber powder according to claim 9 in the preparation of ABS resin or increasing the rubber content of ABS resin.

Images