Water-based SBS latex as well as preparation method and application thereof

Abstract

The invention relates to water-based SBS (styrene-butadiene-styrene) latex as well as a preparation method and application thereof. The water-based SBS latex comprises a dispersed phase part accounting for 5-55wt% of the water-based SBS latex and a continuous phase part formed by water accounting for 45-95wt% of the water-based SBS latex. The water-based SBS latex disclosed by the invention can keep ideal mechanical stability, freeze-thaw stability and storage stability, the possibility of demulsification and segregation of the latex during environmental change is avoided, and the adaptability of the water-based SBS latex is greatly widened. The water-based SBS latex can be used in the fields of asphalt modification, waterproof coatings and adhesives.

Description

Technical Field

[0001] The invention relates to the field of polymer materials, and in particular to a water-based SBS latex and a preparation method and application thereof. Background Art

[0002] SBS (Styrene-Butadiene-Styrene Block Copolymer) is a triblock copolymer with styrene and butadiene as monomers. It has the characteristics of both plastic and rubber and is called the "third generation synthetic rubber". It has excellent tensile strength, large surface friction coefficient, good low temperature performance, excellent electrical properties, good processing performance and other characteristics, becoming the thermoplastic elastomer with the largest consumption. The SBS polymer chain is a combination of two block polymers, the plastic segment and the elastic segment, in a series structure. Each middle polybutadiene segment (PB) is connected to a polystyrene segment (PS) at both ends. The soft segment (PB) and the hard segment (PS) are incompatible with each other. The hard polystyrene segment molecules are associated into physical crosslinking points and are chemically bonded to the middle polybutadiene soft segment. This phase separation structure is called a microscopic two-phase separation structure. The polystyrene segments at both ends of the molecular chain are gathered together to form a physical crosslinking area on the nanoscale, called a micro-region; while the polybutadiene segment forms a soft continuous phase, showing high elasticity.

[0003] In recent years, water-based SBS latex has been widely used in emulsified asphalt modification, adhesives, waterproof coatings and concrete modification due to its advantages of environmental protection, convenient transportation, simple application process, and easy use. It avoids the high energy consumption required for heating operations. At the same time, its application performance is easy to adjust, which is conducive to the expansion of applications.

[0004] The preparation of water-based SBS latex is mainly prepared by an external emulsification method in which an SBS resin solution containing a solvent or a viscosity reducer is emulsified in water by high-speed shearing under the condition of a large amount of surfactants. For example: Zhang Qinqin's doctoral thesis "Study on the influence of emulsification of SBS modified asphalt on its application performance", Luo Zhengbin's master's thesis "Preparation of SBS latex for asphalt and its application in micro-surfacing", including CN105237780B, CN106554470B, etc. Since SBS has a certain microscopic phase separation structure, its own emulsification is poor and difficult to disperse. In the prior art, water-based SBS latex is prepared by dissolving SBS in organic solvents such as toluene and cyclohexane to reduce the viscosity of the resin, then dispersing and emulsifying, and then removing the solvent. Although the addition of solvent can make SBS easier to disperse and emulsify in the presence of surfactants, in the process of removing the solvent, the collision of SBS latex is intensified due to the increase in temperature, and the high temperature will also cause the adsorption-desorption of surfactants to accelerate, thereby causing SBS latex to be very easy to slag, and even demulsification will occur in the process of removing the solvent. Due to the presence of a large amount of surfactants in the system, the rapid volatilization of the solvent can easily produce a large amount of foam during the desolventizing process, resulting in the problem of foam overflow or clogging the pipeline. The slow volatilization of the solvent can seriously affect the production efficiency, and the shearing of SBS latex at high temperature for a long time can also accelerate the unstable situation. In addition, due to the addition of a large amount of surfactants, when SBS latex is applied to fields with relatively high water resistance requirements such as building waterproofing, the problem of decreased water resistance may occur. In addition, the storage stability of water-based SBS latex is also a major problem in the industry. Since the density of SBS is lower than that of water, it is easy to stratify during storage. With the serious stratification, the upper SBS latex squeezes each other more and more seriously. Since the adsorption of the surfactant is non-irreversible adsorption, it eventually leads to the formation of hard agglomerates, which can no longer be dispersed. At present, due to the large particle size of water-based SBS latex, the weak stability of the surfactant causes its freeze-thaw stability and mechanical stability to be very poor, which greatly limits its use. The water-based SBS latex prepared according to the prior art often has the problems of low solid content, instability, and easy demulsification. Meanwhile, poor stability has always been a difficult problem in the industry, which seriously affects the use of water-based SBS latex. Summary of the invention

[0005] Based on the defects of the prior art, the present invention utilizes the high hydrophilicity of PVP to improve its hydrophilicity in view of the strong hydrophobic structure of SBS, and at the same time, after PVP is modified by diisobutylene, the strong compatibility of diisobutylene with the butadiene segment in SBS is utilized to stabilize SBS latex to solve the above problems. At the same time, the modified PVP also has a thickening effect, further improving the stability of SBS latex and avoiding emulsion stratification.

[0006] In order to achieve the above object, in the first aspect of the present invention, there is provided an aqueous SBS latex, wherein the aqueous SBS latex comprises a dispersed phase portion accounting for 5-55wt% of the total weight of the aqueous SBS latex and a continuous phase portion formed of water accounting for 45-95wt% of the total weight of the aqueous SBS latex;

[0007] Further, the dispersed phase part comprises an SBS resin inner layer accounting for 89-98 wt % of the total weight of the dispersed phase, a modified PVP outer layer accounting for 1-10 wt % of the total weight of the dispersed phase, and a solvent accounting for 0.1-1 wt % of the total weight of the dispersed phase.

[0008] In a second aspect of the present invention, a method for preparing an aqueous SBS latex is provided, comprising the steps of:

[0009] A. Prepare SBS glue solution and modified PVP aqueous solution respectively;

[0010] B. Dispersing the SBS glue solution into the modified PVP aqueous solution at high speed to prepare an SBS suspension;

[0011] C. Desolventize the SBS suspension to obtain an aqueous SBS latex.

[0012] In a specific embodiment, a method for preparing an aqueous SBS latex comprises the following steps:

[0013] a. Dissolve the SBS resin in a solvent to prepare a 10-25wt% SBS glue;

[0014] b. Mix the modified PVP with water and set aside;

[0015] c. Disperse the SBS glue into the modified PVP aqueous solution at high speed at 50-70°C to prepare an SBS suspension;

[0016] d. The prepared SBS suspension was evacuated at 60-70°C to remove the solvent until the solvent content was less than 1 wt% (based on the dispersed phase in the SBS latex) to obtain an aqueous SBS latex.

[0017] Preferably, the solvent in step a can be selected from one or both of toluene and cyclohexane, more preferably cyclohexane;

[0018] Preferably, the dissolution temperature in step a is preferably 50-70°C, the dissolution time is, for example, 1-2 hours, and the concentration of the dissolved SBS glue is 15-25wt%, such as 18%, 20%, 23%. If the concentration is too high, the viscosity of the SBS glue is large, which is not conducive to dispersion; if the concentration is too low, more solvent needs to be removed, which increases the desolventizing and affects the efficiency.

[0019] Preferably, the SBS resin described in step a is selected from industrially produced SBS finished products, preferably one or more of the SBS resin of Baling Petrochemical Company, the SBS resin of Asahi Kasei Corporation of Japan, the SBS resin of Anic Company of Italy, the SBS resin of Petrochim Company of Belgium, the SBS resin of Kumho Company of South Korea, the SBS resin of KRATON Company of the United States, etc.; more preferably one or more of YH-792, YH-791, YH-796, YH-188, YH-801, Daogai-2# of Baling Petrochemical Company.

[0020] Preferably, the modified PVP in step b is diisobutylene-modified PVP, specifically obtained by copolymerization of diisobutylene and vinyl pyrrolidone (NVP), and the molar proportion of diisobutylene in the modified PVP is 5-20%.

[0021] The preparation method of the modified PVP is as follows: a solvent and diisobutylene are uniformly mixed in a reaction kettle, an initiator and vinyl pyrrolidone are added, and the modified PVP is obtained after a period of reaction and desolventization.

[0022] Specifically, in the preparation method of the modified PVP, the solvent is a solvent with a boiling point greater than 140° C., such as nitrogen methyl pyrrolidone, dimethylformamide, etc.; the initiator is di-tert-butyl peroxide;

[0023] Specifically, the reaction temperature is 90-130° C., the addition time of the initiator and vinyl pyrrolidone is controlled to be 1-3 hours, and the reaction is continued for 3-8 hours after the addition is completed.

[0024] Specifically, the molar ratio of diisobutylene to vinyl pyrrolidone is 1:5-1:20, preferably 1:4-1:10;

[0025] Specifically, the initiator accounts for 0.1% to 0.5% of the total mass of the monomers (diisobutylene and vinyl pyrrolidone).

[0026] Specifically, the desolventizing operation is a prior art, such as drying at 100-180° C. for 4-8 hours to remove the solvent to obtain the modified PVP.

[0027] Preferably, the modified PVP is dissolved in water to obtain modified PVP aqueous solutions of different concentrations.

[0028] Preferably, the concentration of the modified PVP aqueous solution in step b is 10-20 wt %, which is not particularly limited in the present invention.

[0029] Preferably, in step b, hydrochloric acid or acetic acid is used to control the pH to 2-5, and the prepared modified PVP aqueous solution is heated to 50-70° C. for standby use.

[0030] The modified PVP can control the particle size of the suspension when dispersing the SBS suspension containing a solvent. The more modified PVP is added, the smaller the particle size of the SBS suspension containing a solvent under the same dispersion conditions. However, after the amount of modified PVP added reaches a certain value, the particle size of the suspension will basically not change. A sufficient amount of modified PVP can also improve the stability of the emulsion and the stability of the later product during the solvent removal process of the SBS suspension containing a solvent. As a stabilizer, the modified PVP preferably accounts for 1-10wt% of the total weight of the dispersed phase, more preferably 1-8wt%, and even more preferably 1-5wt%.

[0031] Preferably, in step c, the SBS glue is slowly added to the modified PVP aqueous solution under high-speed dispersion conditions, the dispersion speed is 1000-3000 rpm, preferably 1500-2500 rpm; the high-speed dispersion time is 10-30 min, and a solvent-containing SBS suspension with a particle size of 0.5-25 um is prepared.

[0032] Preferably, the particle size of the SBS suspension containing solvent obtained in step c is preferably controlled at 0.5-25um, more preferably 1-20um. As the solvent evaporates in step d, the dispersed phase of the SBS suspension will shrink in volume during the solvent removal process, so the average particle size of the aqueous SBS latex finally obtained in step d is preferably 2-15um.

[0033] Preferably, the vacuuming in step d is preferably carried out in a rotary evaporator, or in a desolventizing kettle containing a stirring paddle. The temperature during vacuuming is preferably stable at 60-70°C. Preferably, the solvent is removed by slowly reducing the vacuum degree at a stable temperature to prevent the vacuum degree from being too low and causing the material to overflow; preferably, after a large amount of organic solvent is not evaporated, the vacuum degree is adjusted to -0.5 to -0.6 kPa, and the reduced pressure distillation is performed for about 1-3 hours to reduce the solvent content to less than 1% (based on the dispersed phase), and the vacuuming is stopped.

[0034] Preferably, the solid content (dispersed phase portion) of the final aqueous SBS latex accounts for 5-55 wt %, preferably 20-50 wt %, of the total weight of the aqueous SBS latex.

[0035] The third aspect of the present invention provides the use of the above-mentioned water-based SBS latex in the fields of asphalt modification, waterproof coatings, and adhesives.

[0036] Terminology explanation:

[0037] The “average particle size” is the d50 value measured on a German Sympatec wet laser particle size analyzer HELOS / SUCELL (from German Sympatec GmbH).

[0038] The particle size of the SBS suspension is a statistical measurement value using a metallographic microscope SG-51 manufactured by Shanghai Optical Instrument Factory.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] (1) The high hydrophilicity of PVP is used to improve the hydrophilicity of SBS, thus preventing SBS from demulsifying and precipitating in the aqueous phase.

[0041] (2) After PVP is modified by diisobutylene, the strong compatibility of diisobutylene with the butadiene chain segment in SBS can be utilized to greatly improve the stability of SBS latex during devolatilization and greatly reduce the occurrence of demulsification.

[0042] (3) Diisobutylene-modified PVP also has a thickening effect, which further improves the storage stability of SBS latex and avoids emulsion stratification. DETAILED DESCRIPTION

[0043] The present invention is further described in detail below in conjunction with specific examples. However, the examples are not intended to limit the present invention. Unless otherwise indicated, all temperature and pressure units are standard temperature and pressure (STP). Optional addition means addition or non-addition.

[0044] Source of raw materials:

[0045] SBS resin: Baling Petrochemical Company, YH-791, YH-801, Daogai-2#;

[0046] NVP: Shandong Aite Chemical Co., Ltd.;

[0047] Diisobutylene: Hine;

[0048] The other raw materials are commercially available unless otherwise specified.

[0049] Emulsion performance test:

[0050] 1. Storage stability test: Place about 0.5L of sample into a suitable plastic or glass container, leaving about 10% of the space in the bottle. Seal it and place it in a (50±2)℃ constant temperature drying oven. Take it out after 2 weeks and place it at (23±2)℃ for 3h. Open the container and observe whether there is stratification, crusting, lumps and flocculation.

[0051] 2. Freeze-thaw stability: Referring to GB / T 20623-2006, put 50g of latex into a cylindrical plastic container or glass container of about 100ml, be careful not to mix in bubbles, seal it and put it in a -5±2℃ low temperature box, take it out after 18h, and then place it at 23±2℃ for 6h. After repeating this three times, open the container, stir with a glass rod, then apply the latex on a glass plate to obtain a uniform thin layer and observe whether there is any foreign matter such as flocculants.

[0052] 3. Mechanical stability: Weigh (400±0.5) g of the emulsion that has been filtered (pore size: 80 mesh) into a suitable container of about 1000 mL (diameter: about 100 mm, height: about 180 mm), place it on the high-speed disperser base, fix it with a clamp, start the disperser (the stirring head is disc-shaped, diameter: about 40 mm), adjust the speed to 2500 r / min, disperse for 0.5 h, filter again, and use tap water to flush the residue on the inner wall of the container into the filter screen, rinse the filter screen with tap water, and observe whether the emulsion is demulsified and whether there are obvious flocculants.

[0053] 4. Latex solid content test: refer to GB-T 2793-1995 test.

[0054] 5. Softening point test: According to the mass ratio of SBS in SBS latex to asphalt in emulsified base asphalt of 4:100, the SBS latex prepared in the embodiment and the comparative example was added to the Qilu 70# emulsified base asphalt, and the mixture was fully mixed to prepare modified emulsified asphalt. The softening point test of the prepared modified emulsified asphalt was carried out according to the national standard GB / T 4507-2014.

[0055] Modified PVP Preparation Example 1

[0056] (1) Add 100g of nitrogen methyl pyrrolidone and 40g of diisobutylene to a 1L reactor and stir evenly; (2) Add 0.4g of di-tert-butyl peroxide and 360g of vinyl pyrrolidone to a glass bottle and stir evenly. (3) After heating the reactor to 100°C, use a horizontal flow pump to drop the mixed solution in (2) into the reactor for 1 hour. The reaction process is accompanied by stirring. After maintaining the reaction at 100°C for 4 hours, the reaction is completed. (4) The modified PVP solution obtained by the reaction is placed in a vacuum oven at 150°C and dried for 8 hours to remove the solvent to obtain modified PVP-1.

[0057] Modified PVP Preparation Example 2

[0058] (1) Add 150g of dimethylformamide and 80g of diisobutylene to a 1L reactor and stir evenly; (2) Add 0.9g of di-tert-butyl peroxide and 560g of vinyl pyrrolidone to a glass bottle and stir evenly. (3) After heating the reactor to 100°C, use a horizontal flow pump to drop the mixed solution in (2) into the reactor for 2 hours. The reaction process is accompanied by stirring. After maintaining the reaction at 120°C for 3 hours, the reaction is completed. (4) The modified PVP solution obtained by the reaction is placed in a vacuum oven at 150°C and dried for 8 hours to remove the solvent to obtain modified PVP-2.

[0059] Example 1

[0060] In a closed 2L reactor with a reflux device, 200g SBS resin (YH-791) and 600g cyclohexane were mixed, heated to 60°C, stirred at 200r / min for 60min, and the SBS glue containing the solvent was kept warm for standby use. In a closed 3L dispersion reactor with a reflux device, 66g of 10wt% modified PVP-1 aqueous solution was taken, its pH was adjusted to 3 by acetic acid, heated to 60°C, and the SBS glue containing the solvent was added to the aqueous solution of modified PVP through the insulation pipeline under the condition of 2000rpm high-speed dispersion, high-speed dispersion for 20min, sampling and observing the suspension average particle size of about 4.2um under a metallographic microscope, and then stopping dispersion. The dispersed suspension was transferred to a rotary evaporator, heated to 65°C and maintained at a constant temperature, and the solvent was removed by slowly reducing the vacuum degree. After a large amount of solvent was not evaporated, the vacuum degree was adjusted to -0.5kPa, and the reduced pressure distillation was continued for about 2h, and vacuuming was stopped. The temperature was lowered to below 45° C., and the discharged material was filtered to obtain an aqueous SBS latex having an average particle size of 2.7 μm and a solid content of 40.7 wt %.

[0061] Example 2

[0062] In a closed 2L reactor with a reflux device, 110g SBS resin (YH-801) and 600g cyclohexane were mixed, heated to 60°C, stirred at 200r / min for 60min, and the SBS glue containing the solvent was kept warm for standby use. In a closed 3L dispersion reactor with a reflux device, 25g 10wt% modified PVP-1 aqueous solution was taken, its pH was adjusted to 3 using acetic acid, heated to 60°C, and the SBS glue containing the solvent was added to the aqueous solution of modified PVP through the insulation pipeline under the condition of 2000rpm high-speed dispersion, high-speed dispersion for 20min, sampling and observing the suspension under a metallographic microscope. The average particle size of the suspension was about 10um and then stopped dispersing. The dispersed suspension was transferred to a rotary evaporator, heated to 65°C and maintained at a constant temperature, and the solvent was removed by slowly reducing the vacuum degree. After a large amount of solvent was not evaporated, the vacuum degree was adjusted to -0.5kPa, and the reduced pressure distillation was continued for about 2h, and vacuuming was stopped. The temperature was lowered to below 45° C., and the discharged material was filtered to obtain an aqueous SBS latex having an average particle size of 5.6 μm and a solid content of 29.2 wt %.

[0063] Example 3

[0064] In a closed 2L reactor with a reflux device, 200g SBS resin (Daogai-2#) and 600g cyclohexane were mixed, heated to 60°C, stirred at 200r / min for 60min, and the SBS glue containing the solvent was kept warm for standby use. In a closed 3L dispersion reactor with a reflux device, 40g of a 10wt% modified PVP-2 aqueous solution was taken, and its pH was adjusted to 3 using acetic acid, heated to 60°C, and the SBS glue containing the solvent was added to the aqueous solution of the modified PVP through an insulation pipeline under the condition of 2000rpm high-speed dispersion, and high-speed dispersion was performed for 20min. The sample was observed under a metallographic microscope and the average particle size of the suspension was about 13um, and then the dispersion was stopped. The dispersed suspension was transferred to a rotary evaporator, heated to 65°C and maintained at a constant temperature, and the solvent was removed by slowly reducing the vacuum degree. After a large amount of solvent was not evaporated, the vacuum degree was adjusted to -0.5kPa, and the reduced pressure distillation was continued for about 2h, and vacuumization was stopped. The temperature was lowered to below 45° C., and the discharged material was filtered to obtain an aqueous SBS latex having an average particle size of 11.4 μm and a solid content of 41.3 wt %.

[0065] Example 4

[0066] In a closed 2L reactor with a reflux device, 200g SBS resin (YH-188) and 600g cyclohexane were mixed, heated to 60°C, stirred at 200r / min for 60min, and the SBS glue containing the solvent was kept warm for standby use. In a closed 3L dispersion reactor with a reflux device, 20g 10%wt of the modified PVP-2 aqueous solution was taken, and its pH was adjusted to 3 by acetic acid, heated to 60°C, and the SBS glue containing the solvent was added to the modified PVP aqueous solution through the insulation pipeline under the condition of 2000rpm high-speed dispersion, and the high-speed dispersion was 20min. The sample was observed under a metallographic microscope and the average particle size of the suspension was about 16um, and then the dispersion was stopped. The dispersed suspension was transferred to a rotary evaporator, heated to 65°C and maintained at a constant temperature, and the solvent was removed by slowly reducing the vacuum degree. After a large amount of solvent was not evaporated, the vacuum degree was adjusted to -0.5kPa, and the reduced pressure distillation was continued for about 2h, and the vacuum was stopped. The temperature was lowered to below 45° C., and the discharged material was filtered to obtain an aqueous SBS latex having an average particle size of 14.1 μm and a solid content of 42.2% by weight.

[0067] Comparative Example 1

[0068] Example 3 in CN105237780B

[0069] Comparative Example 2

[0070] Example 1 in CN106554470B

[0071] Comparative Example 3

[0072] In a closed 2L reactor with a reflux device, 200g of SBS resin (YH-188) and 600g of cyclohexane were mixed, heated to 60°C, stirred at 200r / min for 60min, and the SBS glue containing the solvent was kept warm for standby use. In a closed 3L dispersion reactor with a reflux device, 2g of OP-10 emulsifier was added to 300g of deionized water, the pH of which was adjusted to 3 using acetic acid, heated to 60°C, and the SBS glue containing the solvent was added to the aqueous solution containing the OP-10 emulsifier through the insulation pipeline under the condition of 2000rpm high-speed dispersion, and high-speed dispersion was performed for 20min. The dispersion was stopped after sampling and observing the average particle size of the suspension under a metallographic microscope to be about 16um. The dispersed suspension was transferred to a rotary evaporator, heated to 65°C and maintained at a constant temperature, and the solvent was removed by slowly reducing the vacuum degree. After no large amount of solvent was evaporated, the vacuum degree was adjusted to -0.5 kPa, and the reduced pressure distillation was continued for about 2 hours, and the vacuum was stopped. The temperature was lowered to below 45°C, and the material was filtered to obtain an aqueous SBS latex with an average particle size of 14.5 um and a solid content of 43% by weight.

[0073] The performance test results of the water-based SBS latex prepared in each embodiment and comparative example are shown in Table 1.

[0074] Table 1 Water-based SBS latex performance test results

[0075]

[0076]

[0077] The water-based SBS latex prepared by the process method of the present invention can maintain ideal mechanical stability, freeze-thaw stability and storage stability by adding modified PVP without reducing the emulsification point of the modified emulsified asphalt, thereby greatly broadening the adaptability of the water-based SBS latex.

Claims

1. A water-based SBS latex, characterized in that: The aqueous SBS latex comprises a dispersed phase portion accounting for 5-55 wt % of the aqueous SBS latex and a continuous phase portion consisting of 45-95 wt % of water; Preferably, the dispersed phase portion comprises an SBS resin inner layer accounting for 89-98 wt % of the total weight of the dispersed phase, an outer modified PVP layer accounting for 1-10 wt % of the total weight of the dispersed phase, and 0.1-1 wt % of the residual solvent after desolventization accounting for 0.1-1 wt % of the total weight of the dispersed phase.

2. The aqueous SBS latex according to claim 1, characterized in that The modified PVP is diisobutylene-modified PVP, which is obtained by copolymerization of diisobutylene and vinyl pyrrolidone, and the molar proportion of diisobutylene in the modified PVP is 5-20%.

3. The aqueous SBS latex according to claim 3, characterized in that The preparation method of the modified PVP is as follows: a solvent and diisobutylene are uniformly mixed in a reaction kettle, an initiator and vinyl pyrrolidone are added, and the modified PVP is obtained after a period of reaction and desolventizing.

4. The aqueous SBS latex according to claim 3, characterized in that In the preparation method of the modified PVP: The solvent is nitrogen methyl pyrrolidone or dimethyl formamide; And / or: the initiator is di-tert-butyl peroxide, and the amount of the initiator is preferably 0.1%-0.5% of the total mass of diisobutylene and vinyl pyrrolidone; and / or: the molar ratio of diisobutylene to vinyl pyrrolidone is 1:4-1:19; Preferably, the reaction temperature is 90-130° C., the addition time of the initiator and vinyl pyrrolidone is controlled to be 1-3 hours, and the reaction is continued for 3-8 hours after the addition is completed.

5. The aqueous SBS latex according to claim 1, characterized in that The solvent is one or two of toluene and cyclohexane; And / or: the SBS is selected from one or more of YH-792, YH-791, YH-796, YH-188, YH-801, Daogai-2#.

6. The aqueous SBS latex according to claim 1, characterized in that The average particle size of the aqueous SBS latex is 0.5-25 um, preferably 1-20 um.

7. A method for preparing an aqueous SBS latex, characterized in that: The method comprises the following steps: a. Prepare SBS glue solution and modified PVP aqueous solution respectively; b. Dispersing the SBS glue at high speed into the modified PVP aqueous solution to prepare an SBS suspension; c. The SBS suspension is subjected to a desolventizing treatment to obtain an aqueous SBS latex.

8. The preparation method according to claim 7, characterized in that: In step a, the concentration of the SBS glue solution is 15-25wt%, and the concentration of the modified PVP aqueous solution is 10-20wt%.

9. The preparation method according to claim 7, characterized in that: In step b, the high-speed dispersion speed is 1000-3000 rpm, preferably 1500-2500 rpm, the high-speed dispersion time is 10-30 min, and the dispersion temperature is 50-70° C.; preferably, the desolventizing in step c is performed by vacuuming.

10. Use of the water-based SBS latex according to any one of claims 1 to 6 or the water-based SBS latex prepared by the preparation method according to claim 7 or 8 in the fields of asphalt modification, waterproof coatings, and adhesives.

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