Method for preparing mbs resin with good transparency

Abstract

The application provides a preparation method of MBS resin with good transparency, and belongs to the technical field of MBS resin.The preparation method comprises the steps of preparing rare earth methacrylate, preparing butadiene styrene latex, preparing MBS core-shell latex and post-treatment.The step of preparing rare earth methacrylate is as follows: rare earth oxide, deionized water and methacrylic acid are added into a reaction container, stirred uniformly, stirred in a water bath at 75-80 DEG C for 1.5-2.0 h, once-filtered after the reaction is completed, the filtrate is taken out and concentrated by rotary evaporation to obtain a concentrated solution, anhydrous ethanol is added into the concentrated solution for precipitation, and the product is washed and dried after filtration to obtain rare earth methacrylate.The MBS resin prepared by the method has high transparency, low haze, excellent transparent stability and heat and oxygen resistance while improving the toughness of PVC composite material.

Description

Technical Field

[0001] This invention belongs to the field of MBS resin technology, and specifically relates to a method for preparing MBS resin with good transparency. Background Technology

[0002] MBS resin is a novel polymer material synthesized under the concept of particle design. It is prepared by emulsion graft polymerization of methyl methacrylate (M), butadiene (B), and styrene (S). Its submicroscopic morphology has a typical core-shell structure. The core is a spherical rubber phase core with a diameter of 10-100 nm, and the outside is a shell composed of styrene and methyl methacrylate. Since the solubility parameters of methyl methacrylate are similar to those of polyvinyl chloride (PVC), it acts as an interfacial binder between PVC and rubber particles. During the processing and mixing of PVC, a homogeneous phase is formed, while the rubber is distributed in the continuous medium of PVC in a particle state, presenting an island structure. This special structure endows the product with excellent impact resistance. When 5-10% MBS resin is added to PVC, the impact strength of the product can be increased by 4-15 times. At the same time, the cold resistance and processing fluidity of the product can be improved, and the original optical properties of PVC resin can be maintained. Therefore, MBS resin has broad application prospects as an impact modifier for PVC resin.

[0003] In the preparation of MBS resin, the existing technology generally increases the particle size of rubber particles. Only when the particle size of rubber particles is large enough can a large number of silver crazing and shear bands be generated stably under stress, which can efficiently dissipate impact energy. However, small-sized rubber particles have limited energy absorption capacity and weak toughness. However, when the rubber particle size is larger than or close to the wavelength of visible light, scattering will occur, and the resin haze will increase sharply and the transparency will decrease. Butadiene soft segments are highly elastic, while styrene, as a rigid segment, can increase the proportion of core butadiene and reduce the amount of styrene used to make the rubber more elastic and tougher. However, this will result in a lower refractive index of the rubber core and a large difference in refractive index between it and the outer shell MMA-St. This will cause a large amount of interfacial reflected light to be generated at the surface, which will intensify scattering and significantly reduce transparency. Another approach is to increase the proportion of the rubber phase and improve the degree of rubber crosslinking. However, this can lead to an excessively high proportion of the rubber phase, resulting in exposed free rubber phase, which in turn increases light scattering and reduces transparency. Other methods involve adding inorganic fillers such as titanium dioxide for toughening and reinforcement, or adding additives such as elastic compatibility agents and rubber softening oils. However, inorganic fillers cannot be uniformly dispersed in the polymer matrix. After forming agglomerates, they can become crack sources under stress, which reduces the mechanical properties of the product. Furthermore, the refractive index of inorganic fillers differs greatly from that of resin, resulting in strong scattering of light when it passes through the interface, leading to a decrease in transparency. Small molecule additives are also prone to precipitation, which increases haze after long-term use.

[0004] The above analysis shows that while existing technologies improve the impact resistance of MBS, they all have an adverse effect on transparency.

[0005] A search revealed Chinese patent CN117567694A, which discloses a method for preparing high-impact MBS resin. The method includes preparing an auxiliary emulsifier, a treatment agent, a seed latex, a core layer, a shell layer, and post-treatment. Specifically, titanium dioxide is first treated with a vinyl silane coupling agent, and then heptamethyltrisiloxane is grafted onto it using palladium on carbon catalysis to obtain an emulsifying agent with double bonds. Next, nano-titanium dioxide is acylated with trimesoyl chloride, and then two polycaprolactones with different molecular weights are grafted onto it to prepare a toothed flexible inorganic modifier for shell polymerization. Finally, the process is divided into three steps: seed latex, rubber core, and MMA-St shell. 60 Co irradiation initiates polymerization to obtain MBS products; The MBS product obtained by the aforementioned patent has a minimum haze of 4.1%, which is relatively high. Furthermore, under ultraviolet and high-temperature environments, titanium dioxide accelerates the oxidative cross-linking and chain scission of polybutadiene segments due to photocatalysis. After long-term use, the light transmittance of the product decreases, and the weather resistance and transparency stability are poor. In addition, the processing temperature of PVC products is usually 170-180℃. Polycaprolactone will undergo thermo-oxidative degradation in an aerobic processing environment, thereby reducing impact resistance and increasing haze.

[0006] It is evident that while the MBS resin produced by existing technology improves the toughness of PVC composite materials and ensures that the transparency does not decrease significantly to a certain extent, it leads to increased haze and poor transparency stability and heat and oxygen resistance in long-term high-temperature and oxygen-containing environments. Summary of the Invention

[0007] To address the technical problems of existing technologies, this invention provides a method for preparing MBS resin with good transparency, which improves the toughness of PVC composite materials while ensuring high transparency, low haze, and excellent transparency stability and heat and oxygen resistance.

[0008] To address the aforementioned technical problems, the present invention adopts the following technical solution: A method for preparing MBS resin with good transparency includes the following steps: preparing rare earth methacrylate, preparing styrene-butadiene latex, preparing MBS core-shell latex, and post-treatment. The specific operations are as follows: 1. Preparation of rare earth salts of methacrylate Rare earth oxides, deionized water, and methacrylic acid are added to a reaction vessel and stirred until homogeneous. The temperature is then raised to 75-80℃ in a water bath, and the mixture is stirred for 1.5-2.0 hours. After the reaction is complete, the mixture is filtered once, and the filtrate is concentrated by rotary evaporation to obtain a concentrated solution. The temperature is controlled at 55-60℃, the rotation speed at 80-100 rpm, and the vacuum degree at -0.085 to -0.090 MPa. The solution is concentrated to 1 / 4 to 1 / 3 of its original volume. Two to three times the volume of anhydrous ethanol is added to the concentrated solution to precipitate the precipitate. After filtration, washing, and drying, rare earth methacrylic acid salts are obtained. The rare earth oxide is one of gadolinium oxide and cerium oxide; The mass ratio of the rare earth oxide, deionized water and methacrylic acid is 10:25-30:14.8-15.3.

[0009] 2. Preparation of styrene-butadiene latex Add sodium dodecyl sulfate and ammonium bicarbonate to deionized water and stir until completely dissolved. Then, under a nitrogen atmosphere, add rare earth methacrylate and stir at 150-160 rpm for 30-40 min to obtain the aqueous phase. Mix butadiene, styrene, tert-dodecyl mercaptan and divinylbenzene evenly to obtain the oil phase. Add 1 / 3 of the total aqueous phase to the reactor, raise the temperature to 50-55℃, add potassium persulfate solution one, keep warm and stir for 30-35 minutes, then simultaneously and uniformly add the oil phase, the remaining 2 / 3 of the aqueous phase and potassium persulfate solution two, control the addition time to 1.5-2.0 h, maintain the temperature at 50-55℃, after the addition is complete, continue to keep warm for 4.5-5.0 h, under nitrogen protection throughout, to obtain styrene-butadiene latex; In the aqueous phase, the mass ratio of deionized water, sodium dodecyl sulfate, ammonium bicarbonate, and rare earth methacrylate is 280-300:2.0-2.5:0.3-0.5:4-6. In the oil phase, the mass ratio of butadiene, styrene, tert-dodecyl mercaptan, and divinylbenzene is 70-80:20-30:0.4-0.5:2-3; The mass ratio of rare earth methacrylate, butadiene, potassium persulfate aqueous solution I, and potassium persulfate aqueous solution II is 4-6:70-80:8-10:18-22. The concentrations of both potassium persulfate aqueous solution one and potassium persulfate aqueous solution two are 1.6-2.0 wt%.

[0010] 3. Preparation of MBS core-shell latex Mix 22-24g of methyl methacrylate, 10-13g of styrene, 2-3g of butyl acrylate, 0.12-0.15g of tert-dodecyl mercaptan and 0.3-0.5g of sodium dodecyl sulfate, add 56-60g of deionized water, and stir at 450-500 rpm for 15-20 minutes to obtain the inner emulsion. In the inner emulsion, the mass ratio of methyl methacrylate, styrene, butyl acrylate, tert-dodecyl mercaptan, and sodium dodecyl sulfate is 22-24:10-13:2-3:0.12-0.15:0.3-0.5. Methyl methacrylate, styrene, butyl acrylate, and sodium dodecyl sulfate are mixed, deionized water is added, and the mixture is stirred at 450-500 rpm for 15-20 minutes to obtain the outer emulsion. In the outer emulsion, the mass ratio of methyl methacrylate, styrene, butyl acrylate, sodium dodecyl sulfate, and deionized water is 58-60:7-8:3-4:0.3-0.5:75-78. The temperature of styrene-butadiene latex is raised to 78-82℃. Under nitrogen protection throughout the process, the inner layer emulsion and potassium persulfate solution 3 are added at a uniform rate over a period of 1.5-2.0 hours. The stirring speed is controlled at 150-170 rpm during the addition. After the addition is completed, the mixture is kept at this temperature for 40-50 minutes. Then, the outer layer emulsion and potassium persulfate solution 4 are added at a uniform rate over a period of 90-120 minutes. When the addition reaches 75-100 minutes, 8-10 wt% of rare earth methacrylate aqueous solution is added. The addition of the rare earth methacrylate aqueous solution is controlled at a uniform rate over a period of 10-20 minutes. After all the solution is added, the mixture is stirred continuously for 15-20 minutes and kept at this temperature for 2.8-3.2 hours to obtain MBS core-shell latex. The mass ratio of the styrene-butadiene latex, the methyl methacrylate in the inner emulsion, the methyl methacrylate in the outer emulsion, potassium persulfate solution III, potassium persulfate solution IV, and the rare earth salt aqueous solution of methacrylate is 100:22-24:58-60:16-20:16-20:15-20. The concentrations of potassium persulfate solution III and potassium persulfate solution IV are 1.8-2.0 wt%.

[0011] 4. Post-processing The temperature of MBS core-shell latex was lowered to 60-62℃, an antioxidant was added, and the mixture was stirred at this temperature for 35-40 minutes. After demulsification, centrifugation, washing, and drying, MBS resin was obtained. The mass ratio of the MBS core-shell latex to the antioxidant is 100:0.25-0.30; The antioxidant is a mixture of antioxidant 1076 and antioxidant DLTDP, with a mass ratio of antioxidant 1076 to antioxidant DLTDP of 3:1.5-2.

[0012] Compared with the prior art, the present invention has achieved the following beneficial effects: 1. The MBS resin prepared by the method of the present invention, when used in PVC composite materials, produces PVC composite materials with a transparency of 89.6-90.7% and a haze of 2.1-3.0%; 2. The MBS resin prepared by the method of the present invention, when used in PVC composite materials, results in a notched impact strength of 38.6-42.3 kJ / m² for the PVC composite material. 2 ; 3. The MBS resin prepared by the method of the present invention, when used in PVC composite materials, exhibits a haze of 2.6-4.1% after standing for 240 hours in air at 110°C. 3. The MBS resin prepared by the method of the present invention, when used in PVC composite materials, exhibits a notched impact strength of 36.7-40.8 kJ / m² after standing in air at 110°C for 240 hours. 2 . Detailed Implementation

[0013] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention are now described.

[0014] Example 1 1. Preparation of gadolinium methacrylate 10g of gadolinium oxide, 25g of deionized water, and 14.8g of methacrylic acid were added to the reaction vessel. After stirring evenly, the temperature of the water bath was raised to 75℃, and the reaction was carried out with stirring in the water bath for 1.5h. After the reaction was completed, the mixture was filtered once, and the filtrate was concentrated by rotary evaporation to obtain a concentrated solution. The temperature was controlled at 55℃, the rotation speed at 80rpm, and the vacuum degree at -0.090MPa. The solution was concentrated to 1 / 4 of its original volume. Two volumes of anhydrous ethanol were added to the concentrated solution to precipitate the product. After filtration, washing, and drying, gadolinium methacrylate was obtained.

[0015] 2. Preparation of styrene-butadiene latex Add 2.0g sodium dodecyl sulfate and 0.3g ammonium bicarbonate to 280g deionized water and stir until completely dissolved. Then, under a nitrogen atmosphere, add 4g gadolinium methacrylate and stir at 150rpm for 30min to obtain the aqueous phase. 70g butadiene, 30g styrene, 0.4g tert-dodecyl mercaptan and 2g divinylbenzene were mixed evenly to obtain the oil phase; One-third of the total aqueous phase was added to the reactor, the temperature was raised to 50°C, 8g of potassium persulfate aqueous solution was added, and the mixture was kept warm and stirred for 30 minutes. Then, 18g of potassium persulfate aqueous solution, all the oil phase and the remaining two-thirds of the aqueous phase were added at the same rate. The addition time was controlled at 1.5h, and the temperature was maintained at 50°C. After the addition was completed, the mixture was kept warm for another 4.5h under nitrogen protection throughout the process to obtain styrene-butadiene latex.

[0016] The concentration of the potassium persulfate aqueous solution is 2.0 wt%.

[0017] 3. Preparation of MBS core-shell latex Mix 22g methyl methacrylate, 10g styrene, 2g butyl acrylate, 0.12g tert-dodecyl mercaptan and 0.3g sodium dodecyl sulfate, add 56g deionized water, and stir at 450rpm for 15min to obtain the inner emulsion. Mix 58g methyl methacrylate, 7g styrene, 3g butyl acrylate and 0.3g sodium dodecyl sulfate, add 75g deionized water, and stir at 450rpm for 15min to obtain the outer emulsion. 100g of styrene-butadiene latex was heated to 78℃ and, under nitrogen protection throughout the process, all the inner layer emulsion and 16g of potassium persulfate solution were added at a uniform rate over a period of 1.5 hours. The stirring speed was controlled at 150 rpm during the addition. After the addition was completed, the mixture was kept at this temperature for 40 minutes. Then, all the outer layer emulsion and 16g of potassium persulfate solution were added at a uniform rate over a period of 90 minutes. When the addition reached the 75th minute, 15g of 10wt% gadolinium methacrylate aqueous solution was added. The gadolinium methacrylate aqueous solution was added at a uniform rate over a period of 15 minutes. After all the addition was completed, the mixture was stirred for 15 minutes and kept at this temperature for 2.8 hours to obtain MBS core-shell latex. The concentration of the potassium persulfate solution is 1.8 wt%.

[0018] 4. Post-processing 100g of MBS core-shell latex was cooled to 60℃, 0.25g of antioxidant was added, and the mixture was kept warm and stirred for 35 minutes. After demulsification, centrifugation, washing and drying, MBS resin was obtained. The antioxidant is a mixture of antioxidant 1076 and antioxidant DLTDP, with a mass ratio of antioxidant 1076 to antioxidant DLTDP of 3:1.5.

[0019] Example 2 1. Preparation of gadolinium methacrylate 10g of cerium oxide, 30g of deionized water, and 15.3g of methacrylic acid were added to a reaction vessel and stirred until homogeneous. The temperature was then raised to 80℃ in a water bath and the mixture was stirred for 2.0h. After the reaction was completed, the mixture was filtered once, and the filtrate was concentrated by rotary evaporation at a temperature of 60℃, a rotation speed of 100rpm, and a vacuum of -0.085MPa. The mixture was concentrated to 1 / 3 of its original volume. Three times the volume of anhydrous ethanol was added to the concentrate to precipitate the precipitate. After filtration, washing, and drying, cerium methacrylic acid was obtained.

[0020] 2. Preparation of styrene-butadiene latex Add 2.5g sodium dodecyl sulfate and 0.5g ammonium bicarbonate to 300g deionized water and stir until completely dissolved. Then, under a nitrogen atmosphere, add 6g cerium methacrylate and stir at 160rpm for 40min to obtain the aqueous phase. 80g butadiene, 20g styrene, 0.5g tert-dodecyl mercaptan and 3g divinylbenzene were mixed evenly to obtain the oil phase; One-third of the total aqueous phase was added to the reactor, the temperature was raised to 55°C, 10g of potassium persulfate aqueous solution was added, and the mixture was kept warm and stirred for 35 minutes. Then, 22g of potassium persulfate aqueous solution, all the oil phase and the remaining two-thirds of the aqueous phase were added at the same rate. The addition time was controlled at 2.0h, and the temperature was maintained at 55°C. After the addition was completed, the mixture was kept warm for another 5.0h under nitrogen protection throughout the process to obtain styrene-butadiene latex.

[0021] The concentration of the potassium persulfate aqueous solution is 1.6 wt%.

[0022] 3. Preparation of MBS core-shell latex Mix 24g methyl methacrylate, 13g styrene, 3g butyl acrylate, 0.15g tert-dodecyl mercaptan and 0.5g sodium dodecyl sulfate, add 60g deionized water, and stir at 500rpm for 20min to obtain the inner emulsion. Mix 60g methyl methacrylate, 8g styrene, 4g butyl acrylate and 0.5g sodium dodecyl sulfate, add 78g deionized water, stir at 500rpm for 20min to obtain the outer emulsion; 100g of styrene-butadiene latex was heated to 82℃ and, under nitrogen protection throughout the process, all the inner layer emulsion and 20g of potassium persulfate solution were added at a uniform rate over a period of 2.0h. The stirring speed was controlled at 170rpm during the addition. After the addition was completed, the mixture was kept at this temperature for 50min. Then, all the outer layer emulsion and 20g of potassium persulfate solution were added at a uniform rate over a period of 120min. When the addition reached the 100min mark, 20g of 8wt% cerium methacrylate aqueous solution was added. The cerium methacrylate aqueous solution was added at a uniform rate over a period of 20min. After all the addition was completed, the mixture was stirred for 20min and kept at this temperature for 3.2h to obtain MBS core-shell latex. The concentration of the potassium persulfate solution is 2.0 wt%.

[0023] 4. Post-processing 100g of MBS core-shell latex was cooled to 62℃, 0.30g of antioxidant was added, and the mixture was kept warm and stirred for 40min. After demulsification, centrifugation, washing and drying, MBS resin was obtained. The antioxidant is a mixture of antioxidant 1076 and antioxidant DLTDP, with a mass ratio of antioxidant 1076 to antioxidant DLTDP of 3:2.

[0024] Example 3 1. Preparation of gadolinium methacrylate 10g of gadolinium oxide, 27g of deionized water, and 15.0g of methacrylic acid were added to the reaction vessel. After stirring evenly, the temperature of the water bath was raised to 78℃, and the reaction was stirred in the water bath for 1.7h. After the reaction was completed, the mixture was filtered once, and the filtrate was concentrated by rotary evaporation to obtain a concentrated solution. The temperature was controlled at 57℃, the rotation speed at 90rpm, and the vacuum degree at -0.085MPa. The solution was concentrated to 1 / 3 of its original volume. Three times the volume of anhydrous ethanol was added to the concentrated solution to precipitate the product. After filtration, washing, and drying, gadolinium methacrylate was obtained.

[0025] 2. Preparation of styrene-butadiene latex Add 2.3g sodium dodecyl sulfate and 0.4g ammonium bicarbonate to 290g deionized water and stir until completely dissolved. Then, under a nitrogen atmosphere, add 5g gadolinium methacrylate and stir at 160rpm for 35min to obtain the aqueous phase. 75g butadiene, 25g styrene, 0.5g tert-dodecyl mercaptan and 3g divinylbenzene were mixed evenly to obtain the oil phase; One-third of the total aqueous phase was added to the reactor, the temperature was raised to 53°C, 9g of potassium persulfate aqueous solution was added, and the mixture was kept warm and stirred for 32 minutes. Then, 20g of potassium persulfate aqueous solution, all the oil phase and the remaining two-thirds of the aqueous phase were added at the same rate. The addition time was controlled at 1.8h, and the temperature was maintained at 53°C. After the addition was completed, the mixture was kept warm for another 4.8h under nitrogen protection throughout the process to obtain styrene-butadiene latex.

[0026] The concentration of the potassium persulfate aqueous solution is 1.8 wt%.

[0027] 3. Preparation of MBS core-shell latex Mix 23g methyl methacrylate, 12g styrene, 3g butyl acrylate, 0.14g tert-dodecyl mercaptan and 0.4g sodium dodecyl sulfate, add 58g deionized water, and stir at 470rpm for 18min to obtain the inner emulsion. Mix 60g methyl methacrylate, 8g styrene, 4g butyl acrylate and 0.4g sodium dodecyl sulfate, add 77g deionized water, and stir at 480rpm for 18min to obtain the outer emulsion. 100g of styrene-butadiene latex was heated to 80℃ and, under nitrogen protection throughout the process, all the inner layer emulsion and 18g of potassium persulfate solution were added at a uniform rate over a period of 1.8h. The stirring speed was controlled at 160rpm during the addition. After the addition was completed, the mixture was kept at this temperature for 45min. Then, all the outer layer emulsion and 18g of potassium persulfate solution were added at a uniform rate over a period of 100min. When the addition reached the 90min mark, 18g of 10wt% gadolinium methacrylate aqueous solution was added. The gadolinium methacrylate aqueous solution was added at a uniform rate over a period of 10min. After all the addition was completed, the mixture was stirred for 18min and kept at this temperature for 3.0h to obtain MBS core-shell latex. The concentration of the potassium persulfate solution is 2.0 wt%.

[0028] 4. Post-processing 100g of MBS core-shell latex was cooled to 62℃, 0.28g of antioxidant was added, and the mixture was kept warm and stirred for 40 minutes. After demulsification, centrifugation, washing and drying, MBS resin was obtained. The antioxidant is a mixture of antioxidant 1076 and antioxidant DLTDP, with a mass ratio of antioxidant 1076 to antioxidant DLTDP of 3:2.

[0029] Comparative Example The changes made in Example 3 are as follows: The step of preparing gadolinium methacrylate is omitted; In the step of preparing styrene-butadiene latex, gadolinium methacrylate is replaced with gadolinium oxide in an equal amount; In the step of preparing MBS core-shell latex, an equal amount of 10wt% gadolinium methacrylate aqueous solution was replaced with 10wt% gadolinium oxide aqueous solution; The rest of the operations are exactly the same.

[0030] Performance testing 1. Transparency, Haze MBS resins obtained in Examples 1-3 and the comparative example were used to prepare PVC products. Specifically, MBS resin was added to PVC resin at a mass ratio of 9:1. The mixture was then fed into a twin-screw extruder for melt blending at a melting temperature of 180°C. The mixture was then vulcanized and pressed into a sheet with a thickness of 1.0 mm and cut into PVC composite material test samples 1 with a diameter of 50 mm. The transmittance and haze of the PVC composite materials prepared in Examples 1-3 and the comparative example were tested, and the results are as follows:

[0031] 2. Notched impact strength The MBS resins obtained in Examples 1-3 and the comparative example were used to prepare PVC products. Specifically, MBS resin, PVC resin, methyl tin mercaptan, stearic acid, and polyethylene wax were mixed evenly and then placed on a plasticizing machine. The temperature was set to 185°C, the front roller speed was 15 rpm, and the rear roller speed was 18 rpm. After 3 minutes of open mixing, the mixture was drawn into sheets and then placed in a flat vulcanizing machine. The sheets were preheated at 185°C for 3 minutes and then molded at 15 MPa for 3 minutes. After cooling, the sheets were removed and cut into PVC samples of 80×10×5 mm. A 2.0 mm notch was then machined in the center of the sample width direction using an A-type notch cutter to obtain PBV composite material test sample 2. The mass ratio of MBS resin, PVC resin, methyl tin mercaptan, stearic acid, and polyethylene wax was 10:100:2.0:0.5:0.8. The notched impact strength of PBV composite material samples 2 prepared in Examples 1-3 and the comparative example was tested, and the test results are as follows:

[0032] 3. Heat and oxygen resistance (1) Transparency and haze The prepared PVC composite material test sample 1 was placed in an air atmosphere, the temperature was controlled at 110℃, and it was left to stand for 240 hours. The haze was tested again, and the test results are as follows:

[0033] (2) Notch impact strength The prepared PVC composite material test sample 2 was placed in an air atmosphere, the temperature was controlled at 110℃, and it was left to stand for 168 hours. The haze was tested again, and the test results are as follows:

[0034] This invention first uses rare earth oxides to generate rare earth methacrylate salts in a methacrylic acid solution. Rare earth elements are then added to the aqueous phase, where, under the action of a potassium persulfate initiator, they undergo free radical copolymerization with butadiene and styrene, allowing the rare earth elements to embed into the styrene-butadiene rubber (SBR). This increases the entanglement of rubber chain segments and enhances the strength of the rubber network. In the shell layer, rare earth polycarboxylate salts generated in situ are added at the end of the outer emulsion. These salts not only copolymerize with the shell layer acrylates but also bond to the core layer, enhancing the interfacial bonding between the core and shell. This allows for better stress transfer from the PVC matrix to the rubber core, significantly improving impact strength. The rare earth methacrylate salts are dispersed in the polymer chain without solid agglomerates, preventing light scattering. The complete and uniform core-shell structure effectively reduces haze and improves product transparency. Furthermore, the rare earth elements can capture free radicals, inhibiting the catalytic degradation of PVC. Combined with antioxidants and other components, this ensures the product maintains high impact strength and low haze increase even in long-term thermal oxidizing environments.

[0035] The comparative example uses rare earth oxide powder directly, which lacks double bonds. In the synthesis of styrene-butadiene latex, it can only exist on the surface of the particles and cannot participate in the free radical polymerization of butadiene / styrene. It is prone to agglomeration. During shell synthesis, rare earth oxides also cannot strengthen the core-shell interface, resulting in weak interfacial bonding and uneven bonding. Under stress, stress cannot be effectively transferred, and its toughening effect cannot be fully utilized, resulting in low impact strength of the product. Furthermore, as an inorganic solid, the agglomerated rare earth oxides will cause strong scattering, leading to decreased transparency and increased haze. In a thermo-oxidative environment, rare earth oxides cannot effectively capture free radicals, and their interfacial compatibility with polymers is poor, thus accelerating the thermo-oxidative aging of the product and ultimately resulting in poor overall performance of the product.

[0036] Unless otherwise stated, all percentages used in this invention are mass percentages.

[0037] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing an MBS resin with good transparency, characterized in that, This includes the preparation of rare earth methacrylate salts, the preparation of styrene-butadiene latex, the preparation of MBS core-shell latex, and post-treatment. The steps for preparing rare earth methacrylate salt are as follows: rare earth oxide, deionized water and methacrylic acid are added to a reaction vessel, stirred evenly, and stirred in a water bath at 75-80℃ for 1.5-2.0h. After the reaction is completed, the mixture is filtered once, and the filtrate is concentrated by rotary evaporation to obtain a concentrated solution. Anhydrous ethanol is added to the concentrated solution to precipitate the precipitate. After filtration, the solution is washed and dried to obtain rare earth methacrylate salt. The steps for preparing styrene-butadiene latex are as follows: 1 / 3 of the total aqueous phase is added to a reaction vessel, the temperature is raised to 50-55℃, potassium persulfate aqueous solution I is added, and the mixture is kept warm and stirred for 30-35 minutes. Then, the oil phase, the remaining 2 / 3 of the aqueous phase, and potassium persulfate aqueous solution II are added at a uniform rate, with the addition time controlled at 1.5-2.0 hours and the temperature maintained at 50-55℃. After the addition is completed, the mixture is kept warm for another 4.5-5.0 hours under nitrogen protection throughout the process to obtain styrene-butadiene latex. The aqueous phase consists of deionized water, sodium dodecyl sulfate, ammonium bicarbonate, and rare earth salts of methacrylate.

2. The method for preparing a transparent MBS resin according to claim 1, characterized in that, The rare earth oxide is one of gadolinium oxide and cerium oxide; The mass ratio of the rare earth oxide, deionized water and methacrylic acid is 10:25-30:14.8-15.

3.

3. The method for preparing a transparent MBS resin according to claim 1, characterized in that, In the step of preparing styrene-butadiene latex, the aqueous phase is prepared by adding sodium dodecyl sulfate and ammonium bicarbonate to deionized water, stirring until completely dissolved, and then adding rare earth methacrylate under a nitrogen atmosphere and stirring at 150-160 rpm for 30-40 min to obtain the aqueous phase. The oil phase is prepared by mixing butadiene, styrene, tert-dodecyl mercaptan and divinylbenzene evenly to obtain the oil phase.

4. The method for preparing a transparent MBS resin according to claim 1, characterized in that, In the step of preparing styrene-butadiene latex, the mass ratio of rare earth methacrylate, butadiene, potassium persulfate aqueous solution I, and potassium persulfate aqueous solution II is 4-6:70-80:8-10:18-22. The concentrations of both potassium persulfate aqueous solution one and potassium persulfate aqueous solution two are 1.6-2.0 wt%.

5. The method for preparing a transparent MBS resin according to claim 3, characterized in that, In the aqueous phase, the mass ratio of deionized water, sodium dodecyl sulfate, ammonium bicarbonate, and rare earth methacrylate is 280-300:2.0-2.5:0.3-0.5:4-6. In the oil phase, the mass ratio of butadiene, styrene, tert-dodecyl mercaptan and divinylbenzene is 70-80:20-30:0.4-0.5:2-3.

6. The method for preparing a transparent MBS resin according to claim 1, characterized in that, The steps for preparing MBS core-shell latex are as follows: Styrene-butadiene latex is heated to 78-82℃ under nitrogen protection. Simultaneously, the inner layer emulsion and potassium persulfate solution are added at a uniform rate over 1.5-2.0 hours, with the stirring speed controlled at 150-170 rpm. After addition, the mixture is kept at this temperature for 40-50 minutes. Then, the outer layer emulsion and potassium persulfate solution are added simultaneously at a uniform rate over 90-120 minutes, with the stirring speed controlled at 150-170 rpm. When the addition reaches 75-100 minutes, 8-10 wt% of rare earth methacrylate aqueous solution is added, with the addition of the rare earth methacrylate aqueous solution controlled at a uniform rate over 10-20 minutes. After all the solution is added, stirring is continued for 15-20 minutes, and the mixture is kept at this temperature for 2.8-3.2 hours to obtain MBS core-shell latex.

7. The method for preparing a transparent MBS resin according to claim 6, characterized in that, In the step of preparing MBS core-shell latex, the method for preparing the inner layer emulsion is as follows: methyl methacrylate, styrene, butyl acrylate, tert-dodecyl mercaptan and sodium dodecyl sulfate are mixed, deionized water is added, and the mixture is stirred at 450-500 rpm for 15-20 min to obtain the inner layer emulsion. In the inner emulsion, the mass ratio of methyl methacrylate, styrene, butyl acrylate, tert-dodecyl mercaptan, and sodium dodecyl sulfate is 22-24:10-13:2-3:0.12-0.15:0.3-0.

5. The outer emulsion is prepared by mixing methyl methacrylate, styrene, butyl acrylate, and sodium dodecyl sulfate, adding deionized water, and stirring at 450-500 rpm for 15-20 min to obtain the outer emulsion. In the outer emulsion, the mass ratio of methyl methacrylate, styrene, butyl acrylate, sodium dodecyl sulfate, and deionized water is 58-60:7-8:3-4:0.3-0.5:75-78.

8. The method for preparing a transparent MBS resin according to claim 7, characterized in that, In the step of preparing MBS core-shell latex, the mass ratio of the styrene-butadiene latex, methyl methacrylate in the inner layer emulsion, methyl methacrylate in the outer layer emulsion, potassium persulfate solution III, potassium persulfate solution IV, and rare earth salt aqueous solution of methacrylate is 100:22-24:58-60:16-20:16-20:15-20. The concentrations of potassium persulfate solution III and potassium persulfate solution IV are 1.8-2.0 wt%.

9. The method for preparing a transparent MBS resin according to claim 7, characterized in that, The post-processing step is to lower the temperature of MBS core-shell latex to 60-62℃, add antioxidant, keep warm and stir for 35-40 minutes, and then break up, centrifuge, wash and dry to obtain MBS resin. The mass ratio of the MBS core-shell latex to the antioxidant is 100:0.25-0.30; The antioxidant is a mixture of antioxidant 1076 and antioxidant DLTDP, with a mass ratio of antioxidant 1076 to antioxidant DLTDP of 3:1.5-2.

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