Carboxylated styrene-butadiene latex with high carboxylic acid content and method for its synthesis

Abstract

This invention provides a high-carboxylic acid content carboxylated styrene-butadiene latex and its synthesis method, belonging to the field of polymer emulsion preparation. The method uses fatty amine polyoxyethylene ether oxide, long-chain alkyl quaternary ammonium salt, or long-chain alkyl quaternary ammonium base as co-emulsifiers, and involves carboxylic acid monomer treatment and emulsion polymerization steps. The surfactants fatty amine polyoxyethylene ether oxide, long-chain alkyl quaternary ammonium salt, or long-chain alkyl quaternary ammonium base act as co-emulsifiers in the emulsion polymerization system, interacting with carboxyl-containing monomers to increase the binding degree between the carboxylic acid monomers and other monomers such as conjugated dienes and styrene. This significantly increases the carboxylic acid group content in the latex polymer and improves the stability of the reaction system. The carboxylated styrene-butadiene latex prepared by this invention has a bound carboxylic acid content of 9%-15%. This invention effectively solves the technical problems of low carboxylic acid content and poor emulsion stability in traditional carboxylated styrene-butadiene latexes.

Description

Technical Field

[0001] This invention provides a high-carboxylic acid content carboxylated styrene-butadiene latex and its synthesis method, belonging to the field of polymer emulsion preparation. It involves a process of pretreating polymerizable carboxylic acid monomers with surfactants, simultaneously improving the stability of the reaction system, significantly increasing the content of carboxylic acid groups in the latex polymer, and resulting in a low viscosity latex system. Background Technology

[0002] Styrene-butadiene latex (SBL) is a synthetic latex typically prepared by free radical emulsion polymerization of styrene and butadiene, usually using water as a solvent. It possesses excellent mechanical properties, good weather resistance, and is environmentally friendly, making it widely used in architectural coatings, industrial adhesives, and rubber products. To further enhance the properties of SBL latex, carboxyl functional groups are usually introduced into the molecular chain of the SBL copolymer to improve the latex's polarity and enhance its adhesive properties.

[0003] The amount of bound carboxyl groups in carboxylated styrene-butadiene latex is controlled by the content of carboxylic acid monomers added to the polymerization system. Traditional emulsion polymerization processes produce carboxylated styrene-butadiene latex with relatively low amounts of carboxylic acid monomers added to the polymerization system (e.g., CA1217295A, CN118307729A), generally between 1% and 5%. Excessive addition of carboxylic acid monomers has adverse effects on the polymerization system, leading to instability, high self-polymerization of carboxylic acid monomers, and a low amount of bound polybutadiene-styrene segments. Chinese patent CN101759825A proposes using a composite emulsifier, combining the anionic emulsifier sodium dodecylbenzenesulfonate and the nonionic emulsifier nonylphenol polyoxyethylene ether, to copolymerize butadiene, styrene, and carboxylic acid monomer-containing emulsion systems. This method uses potassium persulfate as an initiator, and the prepared carboxylated styrene-butadiene latex is suitable for oil and gas field cementing slurries. However, the direct addition of carboxylic acid monomers to the polymerization system results in a high degree of self-polymerization of the carboxylic acid monomers. Japanese patent JP3165534B2 employs anionic free radical emulsion polymerization, with butadiene, styrene, and carboxylic acid-containing monomers added dropwise. This method relatively reduces the degree of self-polymerization of carboxylic acid monomers, but the dropwise addition conditions are harsh, resulting in a high viscosity of the produced carboxylated styrene-butadiene latex. US patent US3817899A controls the latex particle size by adjusting the type and amount of emulsifier and initiator, preparing high-solids-content carboxylated styrene-butadiene latex for use in coatings and adhesives. Carboxylic acid monomers have a significant impact on the latex system and particle nucleation and growth process, easily leading to instability in the carboxylated styrene-butadiene latex system. How to increase the carboxyl content of carboxylated styrene-butadiene latex while simultaneously improving the stability of the latex system is currently a key issue in the field of carboxylated styrene-butadiene manufacturing. Summary of the Invention

[0004] To address the problems of existing technologies, this invention provides a high-carboxylic acid content carboxylated styrene-butadiene latex and its synthesis method. The method involves synthesizing fatty amine polyoxyethylene ether oxides, or using co-emulsifiers such as long-chain alkyl quaternary ammonium salts or long-chain alkyl quaternary ammonium bases to form an inner salt with the carboxylic acid monomer. This inner salt is then mixed with oil-soluble monomers such as styrene, resulting in the carboxylic acid monomers being distributed at the styrene interface. Simultaneously, after mixing with water and emulsifiers, the carboxylic acid monomers are distributed on the surface of the styrene emulsion. This method avoids the problem of carboxylic acid monomers being easily soluble in water and undergoing excessive self-polymerization during conventional carboxylated styrene-butadiene latex polymerization, which reduces the grafting rate between the carboxylic acid monomers and styrene-butadiene rubber. During free radical emulsion polymerization, the binding degree between the carboxylic acid monomers and other monomers such as butadiene and styrene is improved, the degree of self-polymerization of the carboxylic acid monomers is reduced, and the stability of the polymerization system is also improved. This invention effectively solves the problems of low carboxylic acid content and poor emulsion stability in current carboxylated styrene-butadiene latex preparation processes.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for synthesizing carboxylated styrene-butadiene latex with high carboxylic acid content, the method comprising the following steps:

[0007] The first step involves treating the carboxylic acid monomer with a co-emulsifier to obtain the complex;

[0008] Step 1.1, Preparation of co-emulsifier: Dissolve fatty amine polyoxyethylene ether in deionized water, add 30 wt% hydrogen peroxide solution, heat to 65-70℃ and stir for 4-6 hours, then increase the temperature to 75-80℃ and react for 6-8 hours. Distill to remove water, obtaining fatty amine polyoxyethylene ether oxide, which serves as the co-emulsifier. In this step, hydrogen peroxide reacts with the fatty amine polyoxyethylene ether, utilizing the oxidizing property of hydrogen peroxide to oxidize the fatty amine polyoxyethylene ether, forming a fatty amine polyoxyethylene ether oxide containing nitrogen-oxygen coordination bonds. The chemical reaction formula is for the preparation of fatty amine polyoxyethylene ether oxide, where R1 is an alkyl chain with a carbon chain length of 14-22; R2 and R3 are hydrophilic segments of polyoxyethylene ether with an average epoxidation degree of 5-20.

[0009]

[0010] Step 1.2, Pretreatment of carboxylic acid monomers: The co-emulsifier fatty amine polyoxyethylene ether oxide obtained in Step 1.1 is added to the carboxylic acid monomers, and the mixture is stirred at 270-300 r / min to obtain a mixture. In this step, the nitrogen atoms in the fatty amine polyoxyethylene ether oxide are positively charged and form an inner salt with the carboxyl group of the carboxylic acid monomer.

[0011] Step 1.3: The mixture is stirred with styrene monomer at a speed of 270-300 r / min to obtain a styrene mixture. In this step, styrene is the oil phase monomer. Due to the formation of an internal salt between the carboxylic acid monomer and the fatty amine polyoxyethylene ether during the pretreatment process, the presence of the fatty hydrophobic segments of the co-emulsifier enables the directional arrangement and distribution of the carboxylic acid monomer at the styrene interface.

[0012] The second step is the synthesis of carboxylic acid-rich carboxylated styrene-butadiene latex.

[0013] Step 2.1: Add a certain amount of deionized water, electrolyte, emulsifier, dispersant and molecular weight regulator to the reactor, stir and mix, then add the styrene mixture from step (1), continue stirring, and evacuate the reactor to a vacuum state to eliminate the presence of oxygen.

[0014] Step 2.2: After injecting a certain amount of conjugated diene monomer into the reactor, an appropriate amount of initiator is added, and the reactor temperature is raised to a certain temperature to start the polymerization reaction. After a certain reaction time, the conversion rate is tested and found to be qualified. A terminator is added, the temperature is lowered, and the product is discharged to obtain carboxylated styrene-butadiene latex with high carboxylic acid content. In this step, the free radical copolymerization reaction of conjugated diene, styrene, and carboxylic acid monomers at the micelle interface is realized. The micelle interface is formed in step 2.1.

[0015] This invention prepares a stable carboxylated styrene-butadiene emulsion with a high carboxylic acid content by adjusting the type and ratio of co-emulsifier and carboxylic acid monomer in a styrene mixture.

[0016] Further, in step 1.1, by weight, the fatty amine polyoxyethylene ether is 80-120 parts, the deionized water is 150-250 parts, and the hydrogen peroxide solution is 12-28 parts.

[0017] Further, in the styrene mixture of step 1.3, by weight fraction, there are 4-10 parts of co-emulsifier, 5-11 parts of carboxylic acid monomer, and 16-30 parts of styrene.

[0018] Further, the stirring time in step 1.2 is 0.5-1 hour, and the stirring temperature is 25-30°C. The stirring time in step 1.3 is 0.5-1 hour, and the stirring temperature is 25-30°C.

[0019] Further, in step 1.1, the fatty amine polyoxyethylene ether includes one or more mixtures of tetradecylamine polyoxyethylene ether oxide, hexadecylamine polyoxyethylene ether oxide, octadecylamine polyoxyethylene ether oxide, eicosylamine polyoxyethylene ether oxide, and docosylamine polyoxyethylene ether oxide, wherein the degree of epoxidation of the hydrophilic segment of the polyoxyethylene ether is 5-20.

[0020] Furthermore, in step 1.2, the co-emulsifier can be replaced with a long-chain alkyl quaternary ammonium salt or a long-chain alkyl quaternary ammonium base, wherein the carbon chain length of the alkyl group is between 12 and 22.

[0021] Further, the long-chain alkyl quaternary ammonium salt includes alkyltrimethylammonium chloride and long-chain alkyldimethylbenzylammonium bromide. The long-chain alkyl quaternary ammonium base includes alkyltrimethylammonium hydroxide and long-chain alkyldimethylbenzylammonium hydroxide. Specifically: the alkyltrimethylammonium chloride includes one or more mixtures of dodecyl, hexadecyl, and octadecyltrimethylammonium chloride; the long-chain alkyldimethylbenzylammonium hydroxide includes one or more mixtures of dodecyl, tetradecyl, hexadecyl, and octadecyldimethylbenzylammonium hydroxide; the alkyltrimethylammonium hydroxide includes one or more mixtures of hexadecyl, octadecyl, and eicosyltrimethylammonium hydroxide; the long-chain alkyldimethylbenzylammonium bromide includes one or more mixtures of dodecyl, tetradecyl, hexadecyl, and octadecyldimethylbenzylammonium bromide.

[0022] Further, in step (2), by weight fraction, there are 100-130 parts of deionized water, 25-46 parts of styrene mixture, 0.8-1.6 parts of electrolyte, 2-5 parts of emulsifier, 0.8-1.6 parts of dispersant, 0.2-0.5 parts of molecular weight regulator, 33-50 parts of conjugated diene monomer, and 0.7-1.5 parts of initiator.

[0023] Furthermore, in step (2), the reaction temperature is maintained at 60-80℃ in the reactor and the reaction is carried out continuously for about 36-48 hours to obtain styrene-butadiene latex with a high carboxylic acid content and a solid content of 35-40%.

[0024] Further, in step 1.2, the carboxylic acid monomer is selected from one or more of acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, olefinic unsaturated sulfonic acid, olefinic unsaturated phosphate and its salts, polycarboxylic anhydrides and polycarboxylic acid partial ester monomers.

[0025] Furthermore, in step 1.3, the styrene monomer includes one or more of styrene, divinylbenzene, methylstyrene, or their derivatives.

[0026] Further, in step 2.1, the emulsifier includes one or more of potassium oleate, sodium alkylbenzene sulfonate, sodium alkyl sulfate, sodium alkylnaphthalene sulfonate, sodium succinate sulfonate, fatty amine polyoxyethylene ether, and potassium and sodium soaps of disproportionated rosin acid.

[0027] Further, in step 2.1, the conjugated diene monomer includes one or more of butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene, and 1,3-pentadiene.

[0028] Furthermore, in step 2.1, the electrolyte includes one or more of potassium chloride, sodium chloride, ferrous sulfate, potassium dihydrogen phosphate, and dipotassium hydrogen phosphate.

[0029] Furthermore, in step 2.1, the dispersant includes one or more of polyvinyl alcohol, polyquaternary ammonium salt, cellulose and its derivatives.

[0030] Further, in step 2.1, the molecular weight regulator includes one or more of 2-mercaptoethanol, 3-mercaptopropionic acid, and alkyl thiols.

[0031] Furthermore, in step 2.2, the initiator includes one or more of potassium persulfate, sodium persulfate, and ammonium persulfate.

[0032] A carboxylated styrene-butadiene latex with high carboxylic acid content was prepared by the above method, with a solid content of 35%-40%, an average particle size of 400 nm, and a bound carboxylic acid content of up to 9%-15%.

[0033] Compared with existing carboxylated styrene-butadiene emulsion polymerization processes, the present invention has the following advantages:

[0034] In traditional carboxylated styrene-butadiene latex preparation processes, carboxylic acid monomers are directly added to the oil-soluble monomer micelle system. However, their water solubility leads to easy self-polymerization of the carboxylic acid monomers, reducing the degree of copolymerization with other monomers. This invention uses water-soluble carboxylic acid monomers that form internal salts with fatty amine polyoxyethylene ether oxides, or long-chain alkyl quaternary ammonium salts or long-chain alkyl quaternary ammonium bases. This results in the directional distribution of carboxylic acid monomers at the styrene interface, increasing the probability of copolymerization with other monomers and reducing their self-polymerization tendency. This allows for the preparation of carboxylated styrene-butadiene latexes with high carboxylic acid content. Attached Figure Description

[0035] Figure 1(a) is the electrospray mass spectrum of the octadecylamine polyoxyethylene ether-5 oxide prepared in step 1 of Example 1;

[0036] Figure 1(b) is a magnified view of the mass-to-charge ratio in the range of 580-630 m / z in Figure 1(a);

[0037] Figure 2 This is a graph showing the changes in solid content and conversion rate during the polymerization process of carboxylated styrene-butadiene latex in step 3 of Example 1;

[0038] Figure 3 The infrared spectrum of the gel sample prepared after demulsification of the carboxylated styrene-butadiene latex in step 3 of Example 1. Detailed Implementation

[0039] The present invention will be further described below with reference to specific implementation examples, but the present invention is not limited to these examples.

[0040] Example 1

[0041] Step 1: Preparation of octadecylamine polyoxyethylene ether-5 oxide

[0042] 120 parts of octadecylamine polyoxyethylene ether-5 and 250 parts of deionized water were added to a reactor and stirred at 55°C for 2 hours at a stirring speed of 300 r / min. Then, 28 parts of a 30% hydrogen peroxide solution were added dropwise over the next hour. The temperature was raised to 65°C and stirred for 6 hours, followed by a further increase to 75°C and stirring for 8 hours. After the reaction was complete, the water was evaporated until the octadecylamine polyoxyethylene ether-5 oxide content was above 99.5%. The electrospray ionization mass spectrum of octadecylamine polyoxyethylene ether-5 oxide is shown in Figure 1. Figure 1(a) is the electrospray ionization mass spectrum of the octadecylamine polyoxyethylene ether-5 oxide prepared in step 1 of Example 1; Figure 1(b) is a magnified view of the portion of Figure 1(a) with a mass-to-charge ratio of 580-630.

[0043] Step 2: Pretreatment of carboxylic acid monomers

[0044] In a reactor, 11 parts of acrylic acid and 10 parts of octadecylamine polyoxyethylene ether-5 oxide were stirred and mixed for 1 hour at 25°C, and then 16 parts of styrene were added and stirred and mixed for 1 hour at 25°C to obtain a styrene mixture containing carboxylic acid monomers.

[0045] Step 3: Synthesis of high carboxylic acid content carboxylated styrene-butadiene latex

[0046] Add 130 parts deionized water, 1.6 parts potassium chloride, 2.0 parts potassium oleate, 1.6 parts polyquaternium-6 dispersant, and 0.5 parts tert-dodecyl mercaptan to a reactor. After stirring and mixing at 270-300 rpm for half an hour, add 37 parts styrene mixture. After evacuating the reactor to a vacuum state, inject 50 parts butadiene and 1.5 parts potassium persulfate. Raise the temperature to 60°C and carry out the polymerization reaction. After reacting for 48 hours and achieving the required conversion rate, add a terminator and cool to 25°C. Discharge the material and filter it through a 300-mesh filter to obtain carboxylated styrene-butadiene latex with high carboxylic acid content. For changes in solid content and conversion rate during the polymerization process, please refer to [link to relevant documentation]. Figure 2 .

[0047] Step 4: Analysis of Carboxylated Styrene-Butylene Emulsion

[0048] a. Solid content test

[0049] The emulsion was placed in a foil cup for recording mass, and then placed in a forced-air drying oven at 110°C. After constant weight was achieved, the mass of the dried latex was recorded. The ratio of this mass to the mass of the added latex is the emulsion solid content. In Example 1, the emulsion solid content was 39.8%.

[0050] b. Infrared spectroscopy test

[0051] Carboxylated styrene-butadiene emulsion was demulsified to obtain a gel sample. The gel sample preparation method is as follows: the emulsion was dropped into anhydrous ethanol for demulsification, followed by sonication and filtration. The gel sample was then soaked in ethanol again, sonicated and filtered three times, and then soaked in deionized water and sonicated and filtered three times. Finally, the gel sample was dried in a 70℃ forced-air oven until its mass remained unchanged. Infrared spectroscopy was performed in transmission mode at 1705 cm⁻¹. -1 A distinct carboxyl carbonyl peak was observed. Figure 3 ).

[0052] c. Carboxyl content test

[0053] Carboxylated styrene-butadiene latex was demulsified to obtain a gel sample. The gel sample preparation method is as follows: the emulsion was dropped into anhydrous ethanol for demulsification, followed by sonication and filtration. The gel sample was then soaked in ethanol, sonicated and filtered three times, and then soaked in deionized water and sonicated and filtered three times. Finally, the gel sample was dried in a 70°C forced-air oven until its mass remained unchanged. Elemental analysis was used, with 2 mg of gel sample tested for C, H, and N elements, and 3 mg of sample tested for O element. The mass proportion of each monomer in the gel sample was calculated based on the results. In this embodiment, the mass of bound carboxylic acid monomers in the carboxylated styrene-butadiene latex sample accounted for approximately 13.12% of the total monomer mass.

[0054] Example 2

[0055] Step 1: Preparation of octadecylamine polyoxyethylene ether-5 oxide

[0056] Add 100 parts of octadecylamine polyoxyethylene ether-5 and 150 parts of deionized water to the reactor, stir at 55°C for 2 hours at a stirring speed of 300 r / min, then add 28 parts of 30% hydrogen peroxide solution dropwise over the next hour, raise the temperature to 70°C and stir for 4 hours, then raise the temperature to 80°C and stir for 6 hours. After the reaction is complete, evaporate the water until the oxide content of octadecylamine polyoxyethylene ether-5 is above 99.5%.

[0057] Step 2: Pretreatment of carboxylic acid monomers

[0058] In a reactor, 9 parts of acrylic acid and 7 parts of octadecylamine polyoxyethylene ether-5 oxide were stirred and mixed at 30°C for 0.5 h, and then added to 30 parts of styrene. The mixture was stirred and mixed at 30°C for 0.5 h to obtain a styrene mixture containing carboxylic acid monomers.

[0059] Step 3: Synthesis of high carboxylic acid content carboxylated styrene-butadiene latex

[0060] 130 parts of deionized water, 0.8 parts of potassium chloride, 5 parts of potassium oleate, 0.8 parts of polyquaternium-6 dispersant, and 0.2 parts of tert-dodecyl mercaptan were added to a reactor. After stirring and mixing at 270-300 r / min for half an hour, 46 parts of styrene mixture were added. After the reactor was evacuated to a vacuum state, 33 parts of butadiene and 0.7 parts of potassium persulfate were injected. The temperature was raised to 70℃ for polymerization reaction. After the reaction was completed and the conversion rate was qualified, a terminator was added and the temperature was lowered to 25℃. The product was discharged and filtered through a 300-mesh filter to obtain carboxylated styrene-butadiene latex with high carboxylic acid content.

[0061] Step 4: Analysis of Carboxylated Styrene-Butylene Emulsion

[0062] The analytical method for carboxylated styrene-butadiene latex was the same as in Example 1. In Example 2, the solid content of the emulsion was 38.6%. In this example, the mass ratio of bound carboxylic acid monomers to total monomer mass in the carboxylated styrene-butadiene latex sample was 11.73%.

[0063] Example 3

[0064] Step 1: Preparation of octadecylamine polyoxyethylene ether-5 oxide

[0065] 110 parts of octadecylamine polyoxyethylene ether-5 and 200 parts of deionized water were added to the reactor and stirred at 55°C for 2 hours at a stirring speed of 300 r / min. In the next hour, 28 parts of 30% hydrogen peroxide solution were added dropwise. The temperature was raised to 70°C and stirred for 5 hours. The temperature was then raised to 80°C and stirred for 8 hours. After the reaction was completed, the water was evaporated until the oxide content of octadecylamine polyoxyethylene ether-5 was above 99.5%.

[0066] Step 2: Pretreatment of carboxylic acid monomers

[0067] In a reactor, 9 parts of acrylic acid and 4 parts of octadecylamine polyoxyethylene ether-5 oxide were stirred and mixed for 1 hour at 25°C. Then, 16 parts of methylstyrene were added and stirred and mixed for 1 hour at 25°C to obtain a styrene mixture containing carboxylic acid monomers.

[0068] Step 3: Synthesis of high carboxylic acid content carboxylated styrene-butadiene latex

[0069] 100 parts of deionized water, 0.8 parts of potassium dihydrogen phosphate, 2 parts of sodium dodecylbenzenesulfonate, 0.8 parts of polyvinyl alcohol, and 0.2 parts of 2-mercaptoethanol were added to a reactor. After stirring and mixing at 270-300 r / min for half an hour, 29 parts of styrene mixture were added. After the reactor was evacuated to a vacuum state, 33 parts of butadiene and 0.7 parts of ammonium persulfate were injected. The temperature was raised to 80℃ and the polymerization reaction was carried out. After the conversion rate was qualified, a terminator was added and the temperature was lowered to 25℃. The product was discharged and filtered through a 300-mesh filter to obtain carboxylated styrene-butadiene latex with high carboxylic acid content.

[0070] Step 4: The analytical method for carboxylated styrene-butadiene latex is the same as in Example 1. In Example 3, the emulsion solid content was 39.1%. In this example, the mass ratio of bound carboxylic acid monomers in the carboxylated styrene-butadiene latex sample was 14.87%.

[0071] Example 4

[0072] Step 1: Preparation of octadecylamine polyoxyethylene ether-10 oxide

[0073] Add 100 parts of octadecylamine polyoxyethylene ether-10 and 200 parts of deionized water to the reactor, stir at 55°C for 2 hours at a stirring speed of 300 r / min, then add 19 parts of 30% hydrogen peroxide solution dropwise over the next hour, raise the temperature to 70°C and stir for 5 hours, then raise the temperature to 80°C and stir for 8 hours. After the reaction is complete, evaporate the water until the oxide content of octadecylamine polyoxyethylene ether-10 is above 99.5%.

[0074] Step 2: Pretreatment of carboxylic acid monomers

[0075] In a reactor, 5 parts of methacrylic acid and 4 parts of octadecylamine polyoxyethylene ether-10 oxide were stirred and mixed for 1 hour at 25°C, and then added to 16 parts of styrene. The mixture was stirred and mixed for 1 hour at 25°C to obtain a styrene mixture containing carboxylic acid monomers.

[0076] Step 3: Synthesis of high carboxylic acid content carboxylated styrene-butadiene latex

[0077] 110 parts of deionized water, 0.8 parts of potassium chloride, 2 parts of potassium oleate, 0.8 parts of polyquaternium-6 dispersant, and 0.2 parts of tert-dodecyl mercaptan were added to a reactor. After stirring and mixing at 270-300 r / min for half an hour, 25 parts of styrene mixture were added. After the reactor was evacuated to a vacuum state, 33 parts of isoprene and 0.7 parts of potassium persulfate were injected. The temperature was raised to 70℃ for polymerization reaction. After the reaction was completed and the conversion rate was qualified, a terminator was added and the temperature was lowered to 25℃. The product was discharged and filtered through a 300-mesh filter to obtain carboxylated styrene-butadiene latex with high carboxylic acid content.

[0078] Step 4: The analytical method for carboxylated styrene-butadiene latex is the same as in Example 1. In Example 4, the emulsion solid content is 35.3%. In this example, the mass ratio of bound carboxylic acid monomers in the carboxylated styrene-butadiene latex sample is 9.07% of the total monomer mass.

[0079] Example 5

[0080] Step 1: Preparation of octadecylamine polyoxyethylene ether-15 oxide

[0081] Add 100 parts of octadecylamine polyoxyethylene ether-15 and 200 parts of deionized water to the reactor, stir at 55°C for 2 hours at a stirring speed of 300 r / min, then add 16 parts of 30% hydrogen peroxide solution dropwise over the next hour, raise the temperature to 70°C and stir for 5 hours, then raise the temperature to 80°C and stir for 8 hours. After the reaction is complete, evaporate the water until the oxide content of octadecylamine polyoxyethylene ether-15 is above 99.5%.

[0082] Step 2: Pretreatment of carboxylic acid monomers

[0083] In a reactor, 8 parts of acrylic acid and 7 parts of octadecylamine polyoxyethylene ether-15 oxide were stirred and mixed for 1 hour at 25°C. Then, 16 parts of styrene were added at 25°C and stirred and mixed for 1 hour to obtain a styrene mixture containing carboxylic acid monomers.

[0084] Step 3: Synthesis of high carboxylic acid content carboxylated styrene-butadiene latex

[0085] 100 parts of deionized water, 0.8 parts of potassium chloride, 2 parts of potassium oleate, 0.8 parts of polyquaternium-6 dispersant, and 0.2 parts of tert-dodecyl mercaptan were added to a reactor. After stirring and mixing at 270-300 r / min for half an hour, 31 parts of styrene mixture were added. After the reactor was evacuated to a vacuum state, 33 parts of butadiene were injected, and 0.7 parts of potassium persulfate were added. The temperature was raised to 70℃ for polymerization reaction. After the reaction was completed and the conversion rate was qualified, a terminator was added and the temperature was lowered to 25℃. The product was discharged and filtered through a 300-mesh filter to obtain carboxylated styrene-butadiene latex with high carboxylic acid content.

[0086] Step 4: The analytical method for carboxylated styrene-butadiene latex is the same as in Example 1. In Example 5, the emulsion solid content is 38.6%. In this example, the mass ratio of bound carboxylic acid monomers in the carboxylated styrene-butadiene latex sample is 13.57%.

[0087] Example 6

[0088] Step 1: Preparation of octadecylamine polyoxyethylene ether-20 oxide

[0089] Add 100 parts of octadecylamine polyoxyethylene ether-20 and 200 parts of deionized water to the reactor, stir at 55°C for 2 hours at a stirring speed of 300 r / min, then add 12 parts of 30% hydrogen peroxide solution dropwise over the next hour, raise the temperature to 70°C and stir for 5 hours, then raise the temperature to 80°C and stir for 8 hours. After the reaction is complete, evaporate the water until the oxide content of octadecylamine polyoxyethylene ether-20 is above 99.5%.

[0090] Step 2: Pretreatment of carboxylic acid monomers

[0091] In a reactor, 5 parts of acrylic acid and 4 parts of octadecylamine polyoxyethylene ether-20 oxide were stirred and mixed for 1 hour at 25°C, and then 16 parts of styrene were added and stirred and mixed for 1 hour at 25°C to obtain a styrene mixture containing carboxylic acid monomers.

[0092] Step 3: Synthesis of high carboxylic acid content carboxylated styrene-butadiene latex

[0093] 100 parts of deionized water, 0.8 parts of potassium chloride, 2 parts of potassium oleate, 0.8 parts of polyquaternium-6 dispersant, and 0.2 parts of tert-dodecyl mercaptan were added to a reactor. After stirring and mixing at 270-300 r / min for half an hour, 25 parts of styrene mixture were added. After the reactor was evacuated to a vacuum state, 33 parts of butadiene and 0.7 parts of potassium persulfate were injected. The temperature was raised to 70℃ for polymerization reaction. After the reaction was completed and the conversion rate was qualified, a terminator was added and the temperature was lowered to 25℃. The product was discharged and filtered through a 300-mesh filter to obtain carboxylated styrene-butadiene latex with high carboxylic acid content.

[0094] Step 4: The analytical method for carboxylated styrene-butadiene latex is the same as in Example 1. In Example 6, the emulsion solid content was 37.8%. In this example, the mass ratio of bound carboxylic acid monomers to total monomer mass in the carboxylated styrene-butadiene latex sample was 9.13%.

[0095] Example 7

[0096] Step 1: Pretreatment of carboxylic acid monomers

[0097] In a reactor, 5 parts of acrylic acid and 4 parts of hexadecyltrimethylammonium hydroxide were stirred and mixed for 1 hour at 25°C, and then 16 parts of styrene were added and stirred and mixed for 1 hour at 25°C to obtain a styrene mixture containing carboxylic acid monomers.

[0098] Step 2: Synthesis of high carboxylic acid content carboxylated styrene-butadiene latex

[0099] 100 parts of deionized water, 0.8 parts of potassium chloride, 2 parts of potassium oleate, 0.8 parts of polyquaternium-6 dispersant, and 0.2 parts of tert-dodecyl mercaptan were added to a reactor. After stirring and mixing at 270-300 r / min for half an hour, 25 parts of styrene mixture were added. After the reactor was evacuated to a vacuum state, 33 parts of butadiene and 0.7 parts of potassium persulfate were injected. The temperature was raised to 70℃ for polymerization reaction. After the reaction was completed and the conversion rate was qualified, a terminator was added and the temperature was lowered to 25℃. The product was discharged and filtered through a 300-mesh filter to obtain carboxylated styrene-butadiene latex with high carboxylic acid content.

[0100] Step 3: The analytical method for carboxylated styrene-butadiene latex is the same as in Example 1. In Example 7, the emulsion solid content was 37.9%. In this example, the mass ratio of bound carboxylic acid monomers to total monomer mass in the carboxylated styrene-butadiene latex sample was 9.19%.

[0101] Example 8

[0102] Step 1: Pretreatment of carboxylic acid monomers

[0103] In a reactor, 8 parts of acrylic acid and 7 parts of octadecyltrimethylammonium hydroxide were stirred and mixed for 1 hour at 25°C, and then 16 parts of styrene were added and stirred and mixed for 1 hour at 25°C to obtain a styrene mixture containing carboxylic acid monomers.

[0104] Step 2: Synthesis of high carboxylic acid content carboxylated styrene-butadiene latex

[0105] 100 parts of deionized water, 0.8 parts of potassium chloride, 2 parts of potassium oleate, 0.8 parts of polyquaternium-6 dispersant, and 0.2 parts of tert-dodecyl mercaptan were added to a reactor. After stirring and mixing at 270-300 r / min for half an hour, 31 parts of styrene mixture were added. After the reactor was evacuated to a vacuum state, 33 parts of butadiene were injected, and 0.7 parts of potassium persulfate were added. The temperature was raised to 70℃ for polymerization reaction. After the reaction was completed and the conversion rate was qualified, a terminator was added and the temperature was lowered to 25℃. The product was discharged and filtered through a 300-mesh filter to obtain carboxylated styrene-butadiene latex with high carboxylic acid content.

[0106] Step 3: The analytical method for carboxylated styrene-butadiene latex is the same as in Example 1. In Example 8, the emulsion solid content was 38.8%. In this example, the mass ratio of bound carboxylic acid monomers in the carboxylated styrene-butadiene latex sample was 13.62%.

[0107] Example 9

[0108] Step 1: Pretreatment of carboxylic acid monomers

[0109] In a reactor, 5 parts of acrylic acid and 4 parts of hexadecyltrimethylammonium chloride were stirred and mixed for 1 hour at 25°C, and then 16 parts of styrene were added and stirred and mixed for 1 hour at 25°C to obtain a styrene mixture containing carboxylic acid monomers.

[0110] Step 2: Synthesis of high carboxylic acid content carboxylated styrene-butadiene latex

[0111] 100 parts of deionized water, 0.8 parts of potassium chloride, 2 parts of potassium oleate, 0.8 parts of polyquaternium-6 dispersant, and 0.2 parts of tert-dodecyl mercaptan were added to a reactor. After stirring and mixing at 270-300 r / min for half an hour, 25 parts of styrene mixture were added. After the reactor was evacuated to a vacuum state, 33 parts of butadiene and 0.7 parts of potassium persulfate were injected. The temperature was raised to 70℃ for polymerization reaction. After the reaction was completed and the conversion rate was qualified, a terminator was added and the temperature was lowered to 25℃. The product was discharged and filtered through a 300-mesh filter to obtain carboxylated styrene-butadiene latex with high carboxylic acid content.

[0112] Step 3: The analytical method for carboxylated styrene-butadiene latex is the same as in Example 1. In Example 9, the emulsion solid content is 37.7%. In this example, the mass ratio of bound carboxylic acid monomers in the carboxylated styrene-butadiene latex sample is 9.06%.

[0113] Example 10

[0114] Step 1: Pretreatment of carboxylic acid monomers

[0115] In a reactor, 8 parts of acrylic acid and 7 parts of octadecyltrimethylammonium chloride were stirred and mixed for 1 hour at 25°C, and then 16 parts of styrene were added and stirred and mixed for 1 hour at 25°C to obtain a styrene mixture containing carboxylic acid monomers.

[0116] Step 2: Synthesis of high carboxylic acid content carboxylated styrene-butadiene latex

[0117] 100 parts of deionized water, 0.8 parts of potassium chloride, 2 parts of potassium oleate, 0.8 parts of polyquaternium-6 dispersant, and 0.2 parts of tert-dodecyl mercaptan were added to a reactor. After stirring and mixing at 270-300 r / min for half an hour, 31 parts of styrene mixture were added. After the reactor was evacuated to a vacuum state, 33 parts of butadiene were injected, and 0.7 parts of potassium persulfate were added. The temperature was raised to 70℃ for polymerization reaction. After the reaction was completed and the conversion rate was qualified, a terminator was added and the temperature was lowered to 25℃. The product was discharged and filtered through a 300-mesh filter to obtain carboxylated styrene-butadiene latex with high carboxylic acid content.

[0118] Step 3: The analytical method for carboxylated styrene-butadiene latex is the same as in Example 1. In Example 10, the emulsion solid content was 38.4%. In this example, the mass ratio of bound carboxylic acid monomers in the carboxylated styrene-butadiene latex sample was 13.49% of the total monomer mass.

[0119] Example 11

[0120] Step 1: Pretreatment of carboxylic acid monomers

[0121] In a reactor, 5 parts of acrylic acid and 4 parts of octadecyl dimethyl benzyl ammonium hydroxide were stirred and mixed for 1 hour at 25°C, and then added to 16 parts of styrene. The mixture was stirred and mixed for 1 hour at 25°C to obtain a styrene mixture containing carboxylic acid monomers.

[0122] Step 2: Synthesis of high carboxylic acid content carboxylated styrene-butadiene latex

[0123] 100 parts of deionized water, 0.8 parts of potassium chloride, 2 parts of potassium oleate, 0.8 parts of polyquaternium-6 dispersant, and 0.2 parts of tert-dodecyl mercaptan were added to a reactor. After stirring and mixing at 270-300 r / min for half an hour, 25 parts of styrene mixture were added. After the reactor was evacuated to a vacuum state, 33 parts of butadiene and 0.7 parts of potassium persulfate were injected. The temperature was raised to 70℃ for polymerization reaction. After the reaction was completed and the conversion rate was qualified, a terminator was added and the temperature was lowered to 25℃. The product was discharged and filtered through a 300-mesh filter to obtain carboxylated styrene-butadiene latex with high carboxylic acid content.

[0124] Step 3: The analytical method for carboxylated styrene-butadiene latex is the same as in Example 1. In Example 11, the emulsion solid content was 38.1%. In this example, the mass ratio of bound carboxylic acid monomers to total monomer mass in the carboxylated styrene-butadiene latex sample was 9.24%.

[0125] Example 12

[0126] Step 1: Pretreatment of carboxylic acid monomers

[0127] In a reactor, 5 parts of acrylic acid and 4 parts of octadecyl dimethyl benzyl ammonium bromide were stirred and mixed for 1 hour at 25°C, and then 16 parts of styrene were added and stirred and mixed for 1 hour at 25°C to obtain a styrene mixture containing carboxylic acid monomers.

[0128] Step 2: Synthesis of high carboxylic acid content carboxylated styrene-butadiene latex

[0129] 100 parts of deionized water, 0.8 parts of potassium chloride, 2 parts of potassium oleate, 0.8 parts of polyquaternium-6 dispersant, and 0.2 parts of tert-dodecyl mercaptan were added to a reactor. After stirring and mixing at 270-300 r / min for half an hour, 25 parts of styrene mixture were added. After the reactor was evacuated to a vacuum state, 33 parts of butadiene and 0.7 parts of potassium persulfate were injected. The temperature was raised to 70℃ for polymerization reaction. After the reaction was completed and the conversion rate was qualified, a terminator was added and the temperature was lowered to 25℃. The product was discharged and filtered through a 300-mesh filter to obtain carboxylated styrene-butadiene latex with high carboxylic acid content.

[0130] Step 3: The analytical method for carboxylated styrene-butadiene latex is the same as in Example 1. In Example 12, the emulsion solid content was 37.4%. In this example, the mass ratio of bound carboxylic acid monomers to total monomer mass in the carboxylated styrene-butadiene latex sample was 9.11%.

[0131] The above embodiments are merely illustrative of the implementation methods of the present invention, but should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the protection scope of the present invention.

Claims

1. A method for synthesizing carboxylated styrene-butadiene latex with high carboxylic acid content, characterized in that, The synthesis method Includes the following steps: The first step involves treating the carboxylic acid monomer with a co-emulsifier to obtain the complex; Step 1.1, Preparation of co-emulsifier: Dissolve fatty amine polyoxyethylene ether in deionized water, add hydrogen peroxide solution, After the reaction, dehydration is carried out to obtain fatty amine polyoxyethylene ether oxide, which is used as a co-emulsifier; Step 1.2, Pretreatment of carboxylic acid monomers: Add the co-emulsifier to the carboxylic acid monomers and stir and mix at a certain speed to obtain a mixture. The nitrogen atoms in the fatty amine polyoxyethylene ether oxide form an inner salt with the carboxyl group of the carboxylic acid monomer. Step 1.3: The mixture is stirred and mixed with styrene monomer at a certain speed to obtain styrene mixture, thereby achieving the directional arrangement and distribution of carboxylic acid monomer at the styrene interface; The second step is the synthesis of carboxylic acid-containing styrene-butadiene latex with high carboxylic acid content; Step 2.1: After mixing deionized water, electrolyte, emulsifier, dispersant and molecular weight regulator in the reactor, add it to the styrene mixture and stir continuously. Step 2.2: Add conjugated diene monomer and initiator to the reactor, raise the reactor temperature to a certain temperature to carry out the polymerization reaction, test the conversion rate after the reaction and it is qualified, add terminator to cool down and discharge the material, realize the free radical copolymerization reaction of conjugated diene, styrene and carboxylic acid monomers, and obtain carboxylated styrene-butadiene latex with high carboxylic acid content.

2. The method for synthesizing a high-carboxylic acid content carboxylated styrene-butadiene latex according to claim 1, characterized in that, In step 1.1, the fatty amine polyoxyethylene ether includes tetradecylamine polyoxyethylene ether oxide and hexadecylamine polyoxyethylene ether oxide. One or more mixtures of octadecylamine polyoxyethylene ether oxide, eicosylamine polyoxyethylene ether oxide, and docosylamine polyoxyethylene ether oxide, wherein the degree of epoxidation of the hydrophilic segment of the polyoxyethylene ether is 5-20.

3. The method for synthesizing a high-carboxylic acid content carboxylated styrene-butadiene latex according to claim 1, characterized in that, In the first step: In step 1.1, by weight, the fatty amine polyoxyethylene ether is 80-120 parts, deionized water is 150-250 parts, and hydrogen peroxide solution is 12-28 parts. In the styrene mixture of step 1.3, by weight fraction, there are 4-10 parts of co-emulsifier, 5-11 parts of carboxylic acid monomer, and 16-30 parts of styrene; In step 1.1, the mass fraction of the hydrogen peroxide solution is 30 wt%. In step 1.1, the reaction process is as follows: first, the temperature is raised to 65-70℃ and stirred for 4-6 hours, then the temperature is raised to 75-80℃ and reacted for 6-8 hours. In step 1.2, the stirring speed is 270-300 r / min, the stirring time is 0.5-1 h, and the stirring temperature is 25-30℃; in step 1.3, the stirring speed is 270-300 r / min, the stirring time is 0.5-1 h, and the stirring temperature is 25-30℃. In step 2.1, the reactor is evacuated to a vacuum state.

4. The method for synthesizing a high carboxylic acid content carboxylated styrene-butadiene latex according to claim 1, characterized in that, In step 1.2, the carboxylic acid monomer is selected from one or more of acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, olefinic unsaturated sulfonic acid, olefinic unsaturated phosphoric acid and its salts, polycarboxylic anhydrides and polycarboxylic acid partial ester monomers; in step 1.3, the styrene monomer includes one or more of styrene, divinylbenzene, methylstyrene or their derivatives.

5. The method for synthesizing a high-carboxylic acid content carboxylated styrene-butadiene latex according to claim 1, characterized in that, In the second step: In step 2.1, by weight fraction, there are 100-130 parts of deionized water, 25-46 parts of styrene mixture, 0.8-1.6 parts of electrolyte, 2-5 parts of emulsifier, 0.8-1.6 parts of dispersant, 0.2-0.5 parts of molecular weight regulator, 33-50 parts of conjugated diene monomer, and 0.7-1.5 parts of initiator; In step 2.2, the reaction temperature is maintained at 60-80℃ in the reactor and the reaction is carried out continuously for about 36-48 hours to obtain styrene-butadiene latex with a high carboxylic acid content and a solid content of 35-40%.

6. The method for synthesizing a high-carboxylic acid content carboxylated styrene-butadiene latex according to claim 1, characterized in that, In step 2.1: the emulsifier includes one or more of potassium oleate, sodium alkylbenzene sulfonate, sodium alkyl sulfate, sodium alkylnaphthalene sulfonate, sodium succinate sulfonate, fatty amine polyoxyethylene ether, and potassium and sodium soaps of disproportionated rosin acid; the conjugated diene monomer includes one or more of butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene, and 1,3-pentadiene; the electrolyte includes one or more of potassium chloride, sodium chloride, ferrous sulfate, potassium dihydrogen phosphate, and dipotassium hydrogen phosphate; the dispersant includes one or more of polyvinyl alcohol, polyquaternary ammonium salts, cellulose and its derivatives; the molecular weight regulator includes one or more of 2-mercaptoethanol, 3-mercaptopropionic acid, and alkyl thiols; and the initiator includes one or more of potassium persulfate, sodium persulfate, and ammonium persulfate.

7. A carboxylated styrene-butadiene latex with high carboxylic acid content, characterized in that, The carboxylated styrene-butadiene latex is prepared by any one of the synthesis methods described in claims 1-6, with a solid content of 35%-40%, an average particle size of 400 nm, and a combined carboxylic acid content of 9%-15%.

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