Polybutadiene rubber latex, preparation method therefor, and use thereof

Abstract

The present invention relates to the field of polymer resin synthesis, and disclosed are a polybutadiene rubber latex, a preparation method therefor, and a use thereof. The polybutadiene rubber has an average particle size of 295-400 nm, a dispersity index of less than 0.16, and an ellipticity of less than 0.35. The polybutadiene rubber latex provided in the present invention is a large-particle-size butadiene rubber latex, and the rubber has a regular morphology and a uniform particle size dispersity. In the polybutadiene rubber latex preparation method provided in the present invention, the process is simple and easy to control, the reaction time is short, and the production efficiency of large-particle-size polybutadiene rubber can be effectively improved.

Description

Polybutadiene rubber latex, its preparation method and application

[0001] Cross-reference to related applications

[0002] This application claims the benefit of Chinese Patent Application No. 202411185667.3, filed on August 27, 2024, the contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to the field of polymer resin synthesis, specifically to a polybutadiene rubber latex, its preparation method, and its application. Background Technology

[0004] In the production process of ABS resin using emulsion grafting-bulk SAN blending, the rubber polymerization unit is the first polymerization step, and the structural characteristics of the latex affect the final quality of the ABS resin. Due to its high production difficulty and advanced technology, rubber polymerization has become one of the core technologies in ABS resin production. Currently, there are two main preparation processes for large-particle-size (300nm) polybutadiene (PB) latex using emulsion polymerization: one-step and two-step methods. The one-step process directly prepares 300nm PB latex through emulsion polymerization; the two-step process first prepares 80-100nm PB latex through emulsion polymerization, and then agglomerates the 100nm PB latex into 300nm PB latex through an agglomeration process. However, the particle morphology of this latex is irregular and not perfectly spherical. This instability in particle morphology leads to poor grafting polymerization results in poor overall performance of the ABS resin product.

[0005] The one-step polybutadiene polymerization process has the following main problems: First, the reaction time is too long, generally more than 25 hours, resulting in low production efficiency; second, the PB latex produced has a low gel content, and the prepared ABS resin products have large toughness decay, low gloss and low melt flow, which limits the use of the products in some application scenarios.

[0006] The core of the two-step method for preparing large-particle-size polybutadiene latex is the agglomeration process. Essentially, agglomeration involves changes in the way emulsifiers are adsorbed on the surface of latex particles under external stimuli (such as pH, pressure, and temperature changes). This alters the interfacial energy between the latex particles and the continuous phase, thermodynamically disrupting the electric double layer of the latex particles. This causes the particles to aggregate, reducing the interfacial area and enhancing their stability, ultimately forming aggregates of small particles, thus obtaining large-particle-size polybutadiene latex particles. Agglomeration processes can be categorized into chemical agglomeration, polymer agglomeration, and physical agglomeration. For example, CN1840556A designs a method for agglomerating small-particle-size latex using acetic acid, a regenerating agent, a regulator, and different operating methods to scale up small-particle latex with an average particle size of 80-120 nm to large-particle latex with a particle size of 300-700 nm. CN113651903B reports a method for preparing large-particle-size polybutadiene latex based on polymer agglomeration technology. It uses vinyl sulfate or vinyl sulfonate as a reactive emulsifier and an ionic comonomer as the agglomerating agent, achieving excellent agglomeration effect and producing narrow-distribution polybutadiene latex in the 300nm to 500nm range. CN103848942A reports a method for preparing large-particle-size polybutadiene latex using pressure agglomeration. This method involves high-pressure homogenization of small-particle-size butadiene latex, followed by high-pressure agglomeration of the small-particle-size latex into large-particle-size latex.

[0007] Compared to the one-step method for preparing large-particle-size latex, the two-step method for preparing large-particle-size polybutadiene latex has a shorter preparation cycle. From the preparation of small-particle-size latex to agglomeration, it can generally be completed within 12-18 hours, resulting in higher production efficiency. However, the agglomerated latex still contains some voids, allowing some monomers to enter the pores for internal grafting during grafting. Protrusions also exist on the particle surface, causing uneven graft layer thickness. Furthermore, the latex's stability is relatively poor. Summary of the Invention

[0008] The purpose of this invention is to overcome the problems of slow latex polymerization rate and poor particle regularity of agglomerated latex in current polybutadiene production processes, resulting in poor product quality. This invention provides a polybutadiene rubber latex, its preparation method, and its applications. The key to this invention lies in improving the polymerization process of polybutadiene rubber. By controlling the reaction and agglomeration processes and adding additional monomers, the reaction rate is increased, achieving controllable latex particle size and uniform dispersion. Specifically, this invention provides a novel emulsion polymerization method, including small-particle-size emulsion polymerization, micro-agglomeration, and re-shrinkage bonding processes, which can rapidly produce large-particle-size latex.

[0009] The polybutadiene rubber latex provided by this invention is a large-particle-size butadiene rubber latex with regular rubber morphology and uniform particle size dispersion, which can maintain the stability of various properties of the latex.

[0010] To achieve the above objectives, the present invention provides a polybutadiene rubber latex, wherein the polybutadiene rubber has an average particle size of 300-400 nm, a dispersion index of less than 0.16, and an ellipticity of less than 0.35.

[0011] A second aspect of the present invention provides a method for preparing polybutadiene rubber latex, the method comprising:

[0012] (1) Butadiene monomer is polymerized by emulsion polymerization to obtain primary latex with a butadiene monomer conversion rate of over 60%;

[0013] (2) The primary latex is agglomerated using an agglomerating agent to obtain an agglomerated emulsion;

[0014] (3) After mixing the agglomerated emulsion with butadiene monomer, the polymerization is carried out to complete the rubber conditioning and obtain polybutadiene rubber latex.

[0015] A third aspect of the present invention provides a polybutadiene rubber latex prepared by the preparation method described herein.

[0016] The fourth aspect of this invention provides the application of the polybutadiene rubber latex provided by this invention in the production of ABS resin.

[0017] The polybutadiene rubber latex provided by this invention is a large-particle-size butadiene rubber latex with regular rubber morphology and uniform particle size dispersion, which can maintain the stability of various properties of the latex. It can be used as a grafting powder for preparing high-performance ABS resin and as toughening rubber. The preparation method of polybutadiene rubber latex provided by this invention has a simple and easy-to-control process, good repeatability, and short reaction time, which can effectively improve the production efficiency of large-particle-size polybutadiene rubber. Detailed Implementation

[0018] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0019] This invention provides a polybutadiene rubber latex, wherein the polybutadiene rubber has an average particle size of 295-400 nm, a dispersion index of less than 0.16, and an ellipticity of less than 0.35.

[0020] According to a preferred embodiment of the present invention, the polybutadiene rubber latex has an average particle size of 300-350 nm, a dispersion index of less than 0.01, and an ellipticity of less than 0.2.

[0021] In this invention, the gel content of the polybutadiene rubber latex can be selected from a wide range. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the gel content of the polybutadiene rubber latex is 75-85 wt%.

[0022] In this invention, the coagulant content of the polybutadiene rubber latex can be selected from a wide range. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the coagulant content of the polybutadiene rubber latex is less than 0.15 wt%.

[0023] In this invention, the content of agglomerating agent structural units in the solid polybutadiene rubber of the polybutadiene rubber latex can be selected within a wide range. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the solid polybutadiene rubber in the polybutadiene rubber latex contains 1-12 wt% agglomerating agent structural units. The content of agglomerating agent structural units in the solid polybutadiene rubber of the polybutadiene rubber latex is calculated based on the amount of raw materials fed, and will not be elaborated here.

[0024] In this invention, the range of agglomerating agents that can be selected is relatively wide. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the agglomerating agent is selected from one or more of acrylic compounds and acrylate compounds.

[0025] According to a preferred embodiment of the present invention, the solid polybutadiene rubber in the polybutadiene rubber latex contains 3-8 wt% of agglomerating agent structural units.

[0026] According to a preferred embodiment of the present invention, the agglomerating agent is one or more selected from acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, and hydroxyethyl methacrylate.

[0027] The polybutadiene rubber latex provided by this invention is a large-particle-size butadiene rubber latex with regular rubber morphology and uniform particle size dispersion, which can maintain the stability of various properties of the latex and can be used as a grafting powder and toughening rubber for preparing high-performance ABS resin.

[0028] Polybutadiene rubber latex possessing the aforementioned characteristics can achieve the objectives of this invention. There are no special requirements for its preparation method. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the preparation method of the polybutadiene rubber latex includes:

[0029] (1) Butadiene monomer is polymerized by emulsion polymerization to obtain primary latex with a butadiene monomer conversion rate of over 60%;

[0030] (2) The primary latex is agglomerated using an agglomerating agent to obtain an agglomerated emulsion;

[0031] (3) After mixing the agglomerated emulsion with butadiene monomer, the polymerization is carried out to complete the rubber conditioning and obtain polybutadiene rubber latex.

[0032] According to a preferred embodiment of the present invention, in step (1), the emulsion polymerization is carried out in the presence of an initiator, an emulsifier, a chain transfer agent, and an electrolyte; the raw material amounts include: 0.01-1 parts by weight of initiator, 5-15 parts by weight of emulsifier, 0.01-1 parts by weight of chain transfer agent, 10-200 parts by weight of deionized water, 1-6 parts by weight of electrolyte, and 85-105 parts by weight of butadiene monomer.

[0033] In this invention, the range of initiators that can be selected is relatively wide. The following is an illustrative example, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the initiator is selected from one or more of potassium persulfate, ammonium persulfate, and azo initiators. In the embodiments of the invention, potassium persulfate is used as an illustrative example, but it does not limit the scope of the invention.

[0034] In this invention, the range of emulsifiers that can be selected is relatively wide. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the emulsifier is selected from one or more of rosin soap, potassium oleate, potassium fatty acid, potassium disproportionated rosinate, sodium lauryl sulfate, and sodium laurylbenzene sulfonate. It is preferably a mixture of rosin soap and potassium oleate. There are no special requirements for the composition of the mixture. Generally, the content of each emulsifier is not less than 10 wt% based on the total weight of the emulsifier.

[0035] In this invention, there are no special requirements for the type of chain transfer agent. Commonly used chain transfer agents can achieve the purpose of this invention. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the chain transfer agent is selected from one or more of tert-dodecyl mercaptan, n-dodecyl mercaptan, n-octyl mercaptan and isooctyl mercaptan. In the embodiments of this invention, tert-dodecyl mercaptan is used as an illustrative example, but it does not limit the scope of this invention.

[0036] In this invention, the range of electrolytes that can be selected is relatively wide. The following is an illustrative example, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the electrolyte is selected from one or more of potassium carbonate, sodium carbonate, potassium bicarbonate, sodium bicarbonate, sodium chloride, and ammonium chloride. In the embodiments of the invention, potassium carbonate is used as an illustrative example, but it does not limit the scope of the invention.

[0037] According to a preferred embodiment of the present invention, the butadiene monomer conversion rate in step (1) is above 70%.

[0038] According to a preferred embodiment of the present invention, the butadiene monomer conversion rate in step (1) is 70-85%.

[0039] In this invention, the stirring speed in step (1) can be selected from a wide range. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the stirring speed in step (1) is 20-400 rpm, for example, 50 rpm, 100 rpm, 150 rpm, 200 rpm, 250 rpm, 300 rpm, 350 rpm, etc.

[0040] In this invention, the reaction temperature in step (1) can be selected from a wide range. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the reaction temperature in step (1) is 55-85°C, for example, 60°C, 65°C, 70°C, 75°C, 80°C, etc.

[0041] In this invention, the reaction time in step (1) can be selected from a wide range. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the reaction time in step (1) is 6-12h, for example, 7h, 8h, 9h, 10h, or 11h.

[0042] In this invention, the amount of agglomerating agent in step (2) can be selected from a wide range. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the amount of agglomerating agent in step (2) is 1-12 wt% of the butadiene monomer in step (1).

[0043] According to a preferred embodiment of the present invention, the amount of the agglomerating agent is 3-8 wt% of the butadiene monomer in step (1).

[0044] In this invention, there are no special requirements for the type of agglomerating agent. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the agglomerating agent is one or more of acrylic compounds and acrylate compounds.

[0045] According to a preferred embodiment of the present invention, the agglomerating agent is one or more selected from acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, and hydroxyethyl methacrylate.

[0046] In this invention, the aforementioned preferred agglomerating agent can both act as an agglomerating agent to promote the formation of large-particle-size polybutadiene rubber and participate in the reaction as a monomer, thereby increasing the reaction rate.

[0047] In this invention, the stirring speed in step (2) can be selected from a wide range. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the stirring speed in step (2) is 20-400 rpm, for example, 50 rpm, 100 rpm, 150 rpm, 200 rpm, 250 rpm, 300 rpm, 350 rpm, etc.

[0048] In this invention, the agglomeration temperature in step (2) can be selected from a wide range. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the agglomeration temperature in step (2) is 55-85°C, for example, 60°C, 65°C, 70°C, 75°C, 80°C, etc.

[0049] In this invention, the agglomeration time in step (2) can be selected from a wide range. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the agglomeration time in step (2) is 20-45 min, for example, 25 min, 30 min, 35 min, 40 min, etc.

[0050] In this invention, in order to terminate the agglomeration process and ensure the stability of the subsequent emulsion system, after the agglomeration in step (2) is completed, the pH value of the agglomerated emulsion is adjusted to 10-11 using an alkaline substance before proceeding to step (3).

[0051] In this invention, the range of alkaline substances that can be used to adjust the pH value is relatively wide. The following is an illustrative example, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the alkaline substance is one or more of NaOH, KOH, Ca(OH)2, and Al(OH)3. In the embodiments of this invention, KOH is used as an illustrative example, but it does not limit the scope of this invention.

[0052] In this invention, the amount of butadiene monomer used in step (3) can be selected from a wide range. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the amount of butadiene monomer used in step (3) is 3-12 wt% of the butadiene monomer used in step (1).

[0053] According to a preferred embodiment of the present invention, the amount of butadiene monomer used in step (3) is 4-7 wt% of the amount of butadiene monomer used in step (1).

[0054] In this invention, the butadiene monomer conversion rate in step (3) can be selected from a wide range. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the butadiene monomer conversion rate in step (3) is above 90%.

[0055] According to a preferred embodiment of the present invention, the butadiene monomer conversion rate in step (3) is 96-98%.

[0056] In this invention, the preferred amount of butadiene monomer used in step (3) can make the rubber formed after the reaction have a regular shape and uniform particle size dispersion.

[0057] In this invention, the stirring speed in step (3) can be selected from a wide range. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the stirring speed in step (3) is 20-400 rpm, for example, 50 rpm, 100 rpm, 150 rpm, 200 rpm, 250 rpm, 300 rpm, 350 rpm, etc.

[0058] In this invention, the reaction temperature in step (3) can be selected from a wide range. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the reaction temperature in step (3) is 55-85°C, for example, 60°C, 65°C, 70°C, 75°C, 80°C, etc.

[0059] In this invention, the reaction time in step (3) can be selected from a wide range. The following is an illustrative description, but it does not limit the scope of this invention. According to a preferred embodiment of this invention, the reaction time in step (3) is 1-3h, for example, 1.5h, 2h, 2.5h, 3h, etc.

[0060] The method for preparing polybutadiene rubber latex provided by this invention has a simple and easy-to-control process, good repeatability, and short reaction time, which can effectively improve the production efficiency of large-particle-size polybutadiene rubber.

[0061] This invention provides a polybutadiene rubber latex prepared by the preparation method described herein.

[0062] The polybutadiene rubber latex provided by this invention is a large-particle-size butadiene rubber latex with regular rubber morphology and uniform particle size dispersion, which can maintain the stability of various properties of the latex and can be used as a grafting powder and toughening rubber for preparing high-performance ABS resin.

[0063] This invention provides the application of the polybutadiene rubber latex described herein in the production of ABS resin.

[0064] In this invention, the method for calculating the butadiene monomer conversion rate is as follows:

[0065] Take 2g of the final sample and place it in aluminum foil. Dry it in an 80°C oven and weigh it on a dry basis. Conversion rate = dry basis weight / (2 × theoretical solid content).

[0066] The butadiene monomer conversion rate in Table 1 is the total butadiene monomer conversion rate after step (3).

[0067] Methods for testing and calculating the gel content, average particle size, dispersion index, ellipticity, and coagulant content of polybutadiene latex:

[0068] The gel content test measures the amount of cross-linked butadiene relative to the total butadiene polymer. After fully dissolving polybutadiene rubber in toluene, the dissolved portion is filtered out, and the remaining dry basis portion relative to the original dry basis is the gel content.

[0069] The average particle size and dispersion index were determined using a laser particle size analyzer. The specific test method is as follows:

[0070] (1) Turn on the instrument power and preheat for 10-15 minutes;

[0071] (2) When the instrument indicator light turns green, it means that the standby state has ended and the instrument is ready to use (verification method: open the front cover, insert a small piece of white paper into the optical path, if a circular red spot appears on the white paper, it means that the laser is working normally).

[0072] (3) Take 3 large drops of PBL latex and dilute it to 150mL;

[0073] (4) Add an appropriate amount of the sample to be tested into the sample cell, wipe the liquid accumulated on the edge of the sample cell, and the volume of the sample to be tested should exceed 2 / 3 of the height of the sample cell.

[0074] (5) Start the software test function and observe the energy spectrum curve and concentration indication. If the concentration is too low, the sample amount can be increased appropriately.

[0075] (6) Once the energy spectrum is stable, begin the test and record the results.

[0076] Ellipticity: Measured by electron microscopy images of particles, the ellipticity is the difference between the longest diameter and the shortest diameter of the particle, divided by the average particle size.

[0077] The coagulation content is the proportion of dry coagulation in the total latex after filtration through a 120-mesh filter.

[0078] In the following embodiments, unless otherwise specified, the temperature and stirring conditions in steps (1)-(3) are the same.

[0079] Example 1

[0080] (1) Emulsion prepolymerization: Using emulsion polymerization, 0.3 parts by weight of potassium persulfate, 6 parts by weight of rosin soap, 6 parts by weight of potassium oleate, 0.4 parts by weight of tert-dodecyl mercaptan, 150 parts by weight of deionized water, and 4 parts by weight of potassium carbonate were added sequentially to a pressure-resistant polymerization reactor equipped with a stirrer. After sealing, the reactor was purged with nitrogen three times, and then 90 parts by weight of butadiene monomer was added. The stirring speed was 100 rpm, and polymerization was carried out at 70°C for 8 hours to obtain polybutadiene prepolymer latex.

[0081] (2) Rubber microagglomeration process: When the reaction time of the system reaches 8 hours and the conversion rate reaches 70%, 5 parts by weight of methacrylic acid monomer are added to the system. After reacting for 30 minutes, the pH reaches about 9. Then, KOH solution is added to adjust the pH value to about 10.5.

[0082] (3) Rubber conditioning process: Add 5 parts by weight of butadiene to the system and continue the reaction for 2 hours. The average particle size of the rubber latex reaches 300 nm. Cool down and stop the reaction. After degassing and filtration, large particle size polybutadiene latex is obtained.

[0083] The butadiene monomer conversion rate, gel content, average particle size, dispersion index, and coagulant content of polybutadiene latex are shown in Table 1.

[0084] Example 2

[0085] (1) Emulsion prepolymerization: Using emulsion polymerization, 0.3 parts by weight of potassium persulfate, 6 parts by weight of rosin soap, 6 parts by weight of potassium oleate, 0.4 parts by weight of tert-dodecyl mercaptan, 150 parts by weight of deionized water, and 4 parts by weight of potassium carbonate were added sequentially to a pressure-resistant polymerization reactor equipped with a stirrer. After sealing, the reactor was purged with nitrogen three times, and then 90 parts by weight of butadiene monomer was added. The stirring speed was 100 rpm, and polymerization was carried out at 70°C for 8 hours to obtain polybutadiene prepolymer latex.

[0086] (2) Rubber microagglomeration process: When the reaction time of the system reaches 9 hours and the conversion rate reaches 80%, 5 parts by weight of acrylic monomer are added to the system. The reaction is carried out for 30 minutes and the pH reaches about 9. Then KOH solution is added to adjust the pH value to about 10.5.

[0087] (3) Rubber conditioning process: Add 5 parts by weight of butadiene to the system and continue the reaction for 2 hours. The average particle size of the rubber latex reaches 300 nm. Cool down and stop the reaction. After degassing and filtration, large particle size polybutadiene latex is obtained.

[0088] The butadiene monomer conversion rate, gel content, average particle size, dispersion index, and coagulant content of polybutadiene latex are shown in Table 1.

[0089] Example 3

[0090] (1) Emulsion prepolymerization: Using emulsion polymerization, 0.3 parts by weight of potassium persulfate, 6 parts by weight of rosin soap, 6 parts by weight of potassium oleate, 0.4 parts by weight of tert-dodecyl mercaptan, 150 parts by weight of deionized water, and 4 parts by weight of potassium carbonate were added sequentially to a pressure-resistant polymerization reactor equipped with a stirrer. After sealing, the reactor was purged with nitrogen three times, and then 90 parts by weight of butadiene monomer was added. The stirring speed was 100 rpm, and polymerization was carried out at 70°C for 8 hours to obtain polybutadiene prepolymer latex.

[0091] (2) Rubber microagglomeration process: When the reaction time of the system reaches 8 hours and the conversion rate reaches 70%, 5 parts by weight of methyl methacrylate monomer are added to the system. The reaction is carried out for 30 minutes and the pH reaches about 9. Then KOH solution is added to adjust the pH value to about 10.5.

[0092] (3) Rubber conditioning process: Add 5 parts by weight of butadiene to the system and continue the reaction for 2 hours. The average particle size of the rubber latex reaches 300 nm. Cool down and stop the reaction. After degassing and filtration, large particle size polybutadiene latex is obtained.

[0093] The butadiene monomer conversion rate, gel content, average particle size, dispersion index, and coagulant content of polybutadiene latex are shown in Table 1.

[0094] Example 4

[0095] (1) Emulsion prepolymerization: Using emulsion polymerization, 0.3 parts by weight of potassium persulfate, 6 parts by weight of rosin soap, 6 parts by weight of potassium oleate, 0.4 parts by weight of tert-dodecyl mercaptan, 150 parts by weight of deionized water, and 4 parts by weight of potassium carbonate were added sequentially to a pressure-resistant polymerization reactor equipped with a stirrer. After sealing, the reactor was purged with nitrogen three times, and then 90 parts by weight of butadiene monomer was added. The stirring speed was 100 rpm, and polymerization was carried out at 70°C for 8 hours to obtain polybutadiene prepolymer latex.

[0096] (2) Rubber microagglomeration process: When the reaction time of the system reaches 8 hours and the conversion rate reaches 70%, 5 parts by weight of butyl acrylate monomer are added to the system. The reaction is carried out for 30 minutes and the pH reaches about 9. Then KOH solution is added to adjust the pH value to about 10.5.

[0097] (3) Rubber conditioning process: Add 5 parts by weight of butadiene to the system, continue the reaction for 2 hours, cool down and stop the reaction, and obtain large particle size polybutadiene latex after degassing and filtration.

[0098] The butadiene monomer conversion rate, gel content, average particle size, dispersion index, and coagulant content of polybutadiene latex are shown in Table 1.

[0099] Example 5

[0100] (1) Emulsion prepolymerization: Using emulsion polymerization, 0.3 parts by weight of potassium persulfate, 6 parts by weight of rosin soap, 6 parts by weight of potassium oleate, 0.4 parts by weight of tert-dodecyl mercaptan, 150 parts by weight of deionized water, and 4 parts by weight of potassium carbonate were added sequentially to a pressure-resistant polymerization reactor equipped with a stirrer. After sealing, the reactor was purged with nitrogen three times, and then 90 parts by weight of butadiene monomer was added. The stirring speed was 100 rpm, and polymerization was carried out at 70°C for 8 hours to obtain polybutadiene prepolymer latex.

[0101] (2) Rubber microagglomeration process: When the system reaction time reaches 8 hours and the conversion rate reaches 70%, 10 parts by weight of methacrylic acid monomer are added to the system. After reacting for 30 minutes, the pH reaches about 9. Then, KOH solution is added to adjust the pH value to about 10.5.

[0102] (3) Rubber conditioning process: Add 10 parts by weight of butadiene to the system and continue the reaction for 2 hours. The average particle size of the rubber latex reaches 300 nm. Cool down and stop the reaction. After degassing and filtration, large particle size polybutadiene latex is obtained.

[0103] The butadiene monomer conversion rate, gel content, average particle size, dispersion index, and coagulant content of polybutadiene latex are shown in Table 1.

[0104] Example 6

[0105] (1) Emulsion prepolymerization: Using emulsion polymerization, 0.3 parts by weight of potassium persulfate, 6 parts by weight of rosin soap, 6 parts by weight of potassium oleate, 0.4 parts by weight of tert-dodecyl mercaptan, 150 parts by weight of deionized water, and 4 parts by weight of potassium carbonate were added sequentially to a pressure-resistant polymerization reactor equipped with a stirrer. After sealing, the reactor was purged with nitrogen three times, and then 90 parts by weight of butadiene monomer was added. The stirring speed was 100 rpm, and polymerization was carried out at 70°C for 8 hours to obtain polybutadiene prepolymer latex.

[0106] (2) Rubber microagglomeration process: When the reaction time of the system reaches 8 hours and the conversion rate reaches 70%, 5 parts by weight of methacrylic acid monomer are added to the system. After reacting for 30 minutes, the pH reaches about 9. Then, KOH solution is added to adjust the pH value to about 10.5.

[0107] (3) Rubber conditioning process: Add 10 parts by weight of butadiene to the system and continue the reaction for 2 hours. The average particle size of the rubber latex reaches 300 nm. Cool down and stop the reaction. After degassing and filtration, large particle size polybutadiene latex is obtained.

[0108] The butadiene monomer conversion rate, gel content, average particle size, dispersion index, and coagulant content of polybutadiene latex are shown in Table 1.

[0109] Example 7

[0110] (1) Emulsion prepolymerization: Using emulsion polymerization, 0.3 parts by weight of potassium persulfate, 6 parts by weight of rosin soap, 6 parts by weight of potassium oleate, 0.4 parts by weight of tert-dodecyl mercaptan, 150 parts by weight of deionized water, and 4 parts by weight of potassium carbonate were added sequentially to a pressure-resistant polymerization reactor equipped with a stirrer. After sealing, the reactor was purged with nitrogen three times, and then 90 parts by weight of butadiene monomer was added. The stirring speed was 100 rpm, and polymerization was carried out at 70°C for 8 hours to obtain polybutadiene prepolymer latex.

[0111] (2) Rubber microagglomeration process: When the reaction time of the system reaches 8 hours and the conversion rate reaches more than 70%, add 1 part by weight of methacrylic acid monomer to the system, react for 30 minutes, and the pH reaches about 9. Then add KOH solution to adjust the pH value to about 10.5.

[0112] (3) Rubber conditioning process: Add 5 parts by weight of butadiene to the system and continue the reaction for 2 hours. The average particle size of the rubber latex reaches about 300 nm. Cool down and stop the reaction. After degassing and filtration, large particle size polybutadiene latex is obtained.

[0113] The butadiene monomer conversion rate, gel content, average particle size, dispersion index, and coagulant content of polybutadiene latex are shown in Table 1.

[0114] Comparative Example 1

[0115] (1) Emulsion polymerization: Using emulsion polymerization, 0.3 parts by weight of potassium persulfate, 6 parts by weight of rosin soap, 6 parts by weight of potassium oleate, 0.4 parts by weight of tert-dodecyl mercaptan, 150 parts by weight of deionized water, and 4 parts by weight of potassium carbonate were added sequentially to a pressure-resistant polymerization reactor equipped with a stirrer. After sealing, the reactor was purged with nitrogen three times, and then 95 parts by weight of butadiene monomer was added. The stirring speed was 100 rpm, and polymerization was carried out at 70°C for 12 hours. The temperature was then lowered and the reaction was stopped to obtain polybutadiene small particle size latex.

[0116] (2) Rubber agglomeration process: Add 5 parts by weight of the polymer agglomerant provided in Example 1 of CN113651903B to the system, stir for 15 min, and end the reaction to obtain large particle size polybutadiene latex. Polybutadiene does not have agglomerant structural units.

[0117] The butadiene monomer conversion rate, gel content, average particle size, dispersion index, and coagulant content of polybutadiene latex are shown in Table 1.

[0118] Comparative Example 2

[0119] (1) Emulsion polymerization: Using emulsion polymerization, 0.3 parts by weight of potassium persulfate, 6 parts by weight of rosin soap, 6 parts by weight of potassium oleate, 0.4 parts by weight of tert-dodecyl mercaptan, 150 parts by weight of deionized water, and 4 parts by weight of potassium carbonate were added sequentially to a pressure-resistant polymerization reactor equipped with a stirrer. After sealing, the reactor was purged with nitrogen three times, and then 95 parts by weight of butadiene monomer was added. The stirring speed was 100 rpm, and polymerization was carried out at 70°C for 12 hours. The temperature was then lowered and the reaction was stopped to obtain polybutadiene small particle size latex.

[0120] (2) Rubber agglomeration process: Add 5 parts by weight of 5% acetic acid solution to the system, stir for 15 minutes, then stop the reaction, add KOH solution to adjust the pH value of the agglomerated latex to 10.5 to ensure the stable storage of the latex, and obtain large particle size polybutadiene latex. Polybutadiene does not have agglomerating agent structural units.

[0121] The butadiene monomer conversion rate, gel content, average particle size, dispersion index, and coagulant content of polybutadiene latex are shown in Table 1.

[0122] Table 1 Monomer conversion rate and physical properties of polybutadiene latex

[0123] The preferred embodiments of the present invention have been described above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various specific technical features in any suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A polybutadiene rubber latex, characterized in that, The polybutadiene rubber has an average particle size of 295-400 nm, a dispersion index of less than 0.16, and an ellipticity of less than 0.

35.

2. The latex according to claim 1, characterized in that, The polybutadiene rubber has an average particle size of 300-350 nm, a dispersion index of less than 0.01, and an ellipticity of less than 0.

2.

3. The latex according to claim 1 or 2, characterized in that, The latex has a gel content of 75-85 wt% and / or a coagulation content of less than 0.15 wt%.

4. The latex according to claim 1 or 2, characterized in that, The solid polybutadiene rubber in the latex contains 1-12 wt% of agglomerating agent structural units; and / or The agglomerating agent is selected from one or more of acrylic compounds and acrylate compounds.

5. The latex according to claim 4, characterized in that, The solid polybutadiene rubber in the latex contains 3-8 wt% agglomerating agent structural units; and / or The agglomerating agent is one or more of the following: acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, and hydroxyethyl methacrylate.

6. A method for preparing polybutadiene rubber latex, characterized in that, The method includes: (1) Butadiene monomer is polymerized by emulsion polymerization to obtain primary latex with a butadiene monomer conversion rate of over 60%; (2) The primary latex is agglomerated using an agglomerating agent to obtain an agglomerated emulsion; (3) After mixing the agglomerated emulsion with butadiene monomer, the polymerization is carried out to complete the rubber conditioning and obtain polybutadiene rubber latex.

7. The method according to claim 6, characterized in that, In step (1), the emulsion polymerization is carried out in the presence of an initiator, an emulsifier, a chain transfer agent, and an electrolyte; the raw material amounts include: 0.01-1 parts by weight of initiator, 5-15 parts by weight of emulsifier, 0.01-1 parts by weight of chain transfer agent, 10-200 parts by weight of deionized water, 1-6 parts by weight of electrolyte, and 85-105 parts by weight of butadiene monomer.

8. The method according to claim 7, characterized in that, In step (1), The initiator is selected from one or more of potassium persulfate, ammonium persulfate, and azo initiators; and / or The emulsifier is selected from one or more of rosin soap, potassium oleate, potassium fatty acid, potassium disproportionated rosinate, sodium lauryl sulfate, and sodium dodecylbenzene sulfonate; and / or The chain transfer agent is selected from one or more of tert-dodecyl mercaptan, n-dodecyl mercaptan, n-octyl mercaptan, and isooctyl mercaptan; and / or The electrolyte is selected from one or more of potassium carbonate, sodium carbonate, potassium bicarbonate, sodium bicarbonate, sodium chloride, and ammonium chloride.

9. The method according to claim 6, characterized in that, In step (1), the butadiene monomer conversion rate is above 70%.

10. The method according to claim 6, characterized in that, In step (1), the butadiene monomer conversion rate is 70-85%.

11. The method according to claim 6, characterized in that, In step (1), the conditions for emulsion polymerization include: The stirring speed is 20-400 rpm; and / or The reaction temperature is 55-85℃; and / or The reaction time is 6-12 hours.

12. The method according to claim 6, characterized in that, In step (2), The amount of agglomerating agent used is 1-12 wt% of the butadiene monomer in step (1); and / or The agglomerating agent is selected from one or more of acrylic compounds and acrylate compounds.

13. The method according to claim 11, characterized in that, In step (2), The amount of agglomerating agent used is 3-8 wt% of the butadiene monomer in step (1); and / or The agglomerating agent is one or more of the following: acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, and hydroxyethyl methacrylate.

14. The method according to claim 6, characterized in that, The agglomeration conditions in step (2) include: The stirring speed is 20-400 rpm; and / or Temperature is 55-85℃; and / or The time is 20-45 minutes.

15. The method according to claim 6, characterized in that, After the agglomeration in step (2) is completed, the pH of the agglomerated emulsion is adjusted to 10-11 using an alkaline substance before proceeding to step (3).

16. The method according to claim 15, characterized in that, The alkaline substance is one or more of NaOH, KOH, Ca(OH)2, and Al(OH)3.

17. The method according to claim 6, characterized in that, In step (3), The amount of butadiene monomer used is 3-12 wt% of the butadiene monomer used in step (1); and / or The butadiene monomer conversion rate is over 90%.

18. The method according to claim 6, characterized in that, In step (3), The amount of butadiene monomer used is 4-7 wt% of the butadiene monomer used in step (1); and / or The butadiene monomer conversion rate is 96-98%.

19. The method according to claim 6, characterized in that, The rubber conditioning conditions in step (3) include: The stirring speed is 20-400 rpm; and / or The reaction temperature is 55-85℃; and / or The reaction time is 1-3 hours.

20. The polybutadiene rubber latex prepared by the preparation method according to any one of claims 6-19.

21. The use of the polybutadiene rubber latex according to any one of claims 1-5, 20 in the production of ABS resin.

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