Styrene-butadiene latex with high freeze-thaw stability and preparation method thereof

Abstract

The invention discloses styrene-butadiene latex with high freeze-thaw stability and a preparation method thereof, and relates to the technical field of styrene-butadiene latex. The styrene-butadiene latex is prepared from the following raw materials in parts by weight: 20 to 40 parts of styrene, 60 to 80 parts of butadiene, 10 to 15 parts of glycerol ester of rosin, 1 to 5 parts of compound emulsifier, 1 to 3 parts of hydrophilic functional monomer, 0.5 to 1 part of electrolyte, 2 to 5 parts of thickening agent, 0.6 to 1.5 parts of initiator and 150 to 200 parts of deionized water. According to the preparation method disclosed by the invention, interface damage, particle coalescence and ice crystal growth in a repeated freezing and thawing process are resisted through triple synergy of interface strengthening of rosin glyceride, colloid stability of the compound emulsifier and network construction of monomers, so that exponential improvement of the stability is realized, and a theoretical basis is provided for design of a high-performance latex material.

Description

Technical Field

[0001] This invention belongs to the field of styrene-butadiene latex technology, and more specifically relates to a styrene-butadiene latex with high freeze-thaw stability and its preparation method. Background Technology

[0002] Styrene-butadiene latex (SBL) is an important synthetic latex widely used in paper coatings, carpet backings, adhesives, and building waterproofing materials. However, SBL is prone to freeze-thaw instability at low temperatures, leading to latex particle aggregation, demulsification, increased viscosity, and even gelation, severely affecting its storage stability and application performance.

[0003] Traditional methods for improving the freeze-thaw stability of styrene-butadiene rubber (SBR) latex include adding antifreeze agents (such as ethylene glycol and urea), adjusting the emulsification system (such as using composite emulsifiers), or introducing functional monomers (such as acrylic acid and methacrylic acid) to enhance the hydrophilicity of the rubber particle surface. However, these methods often suffer from high costs, negative impacts on the mechanical properties of the latex, or insufficient environmental friendliness. Therefore, developing a SBR latex with high freeze-thaw stability without compromising the overall performance of the latex is of great significance. Summary of the Invention

[0004] This invention provides a styrene-butadiene latex with high freeze-thaw stability and its preparation method, overcoming the shortcomings of poor freeze-thaw stability of styrene-butadiene latex in the prior art.

[0005] This invention provides a styrene-butadiene latex with high freeze-thaw stability, wherein the styrene-butadiene latex comprises the following raw materials in parts by weight: 20-40 parts styrene, 60-80 parts butadiene, 10-15 parts rosin glycerol ester, 1-5 parts composite emulsifier, 1-3 parts hydrophilic functional monomer, 0.5-1 part electrolyte, 2-5 parts thickener, 0.6-1.5 parts initiator, and 150-200 parts deionized water.

[0006] Compared with the prior art, the present invention creatively adds rosin glycerol ester and electrolyte to the raw materials. This is because the inventors discovered that rosin glycerol ester, composite emulsifier and hydrophilic functional monomer have a synergistic effect. When the three are used in combination, they can significantly improve the mechanical properties of styrene-butadiene latex and improve freeze-thaw stability.

[0007] Specifically, rosin glycerol esters enhance the inter-particle forces through physical entanglement, forming an elastic network that inhibits particle aggregation at low temperatures. Furthermore, as a natural tackifying resin, the rosin ester groups in its molecular structure can entangle with the styrene segments on the surface of styrene-butadiene latex particles via van der Waals forces, forming a resin-rubber interpenetrating network. During freeze-thaw cycles, this network absorbs the mechanical stress generated by ice crystal expansion through elastic deformation, preventing latex particles from agglomerating and breaking down due to direct compression.

[0008] Meanwhile, the emulsifier can encapsulate the tiny particles of rosin glycerol ester, preventing their aggregation through steric hindrance. When the mass ratio of emulsifier to rosin glycerol ester is 1:3 to 1:10, especially when the mass ratio is 1:4, the dispersed particle size of the resin in the latex can be reduced from 500 nm to below 100 nm, ensuring its uniform distribution at the particle interface and avoiding abrupt changes in colloidal viscosity caused by excessively high local concentrations.

[0009] In addition, the composite emulsifier forms a double protective film on the surface of latex particles, and the electrolyte enhances the electrostatic repulsion between particles by adjusting the potential, preventing demulsification caused by intensified particle collisions during freeze-thaw cycles.

[0010] In summary, this invention achieves an exponential improvement in the stability of latex systems during freeze-thaw cycles through a triple synergistic effect: interfacial reinforcement by rosin glycerol esters, colloidal stabilization by composite emulsifiers, and network construction by monomers, enabling the latex system to simultaneously resist interfacial damage, particle aggregation, and ice crystal growth. This synergistic effect is essentially a multi-scale coupling of physical entanglement, chemical cross-linking, and colloidal chemical effects, providing a theoretical basis for the design of high-performance latex materials.

[0011] Furthermore, the composite emulsifier is prepared by compounding sodium dodecylbenzenesulfonate and alkylphenol polyoxyethylene ether in a mass ratio of 1:1 to 1:3.

[0012] Compared to existing technologies, when the SDBS:APEO ratio is 1:1 to 1:3, the adsorption layer thickness is increased, the potential is stabilized, and the viscosity of the hydration layer is increased, forming a dual stabilizing barrier. Furthermore, the polyoxyethylene chains of APEO encapsulate rosin glycerol ester molecules through hydrogen bonds, significantly reducing their dispersed particle size and ensuring uniform distribution at the latex particle interface. The charge repulsion of SDBS prevents rosin glycerol ester particles from agglomerating due to van der Waals forces, thus improving the dispersion stability of the resin in the latex and further enhancing freeze-thaw stability.

[0013] Furthermore, the hydrophilic functional monomer is composed of hydroxyethyl methacrylate and diallyl terephthalate in a mass ratio of 1:5.

[0014] Compared with existing technologies, using the above-mentioned specific mass ratio of hydrophilic functional monomers can significantly enhance the synergistic effect with rosin glycerol esters and composite emulsifiers, improve the stability of the styrene-butadiene latex interface, and thus improve freeze-thaw stability.

[0015] Furthermore, the electrolyte includes at least one of sodium chloride and potassium chloride.

[0016] Furthermore, the thickener includes at least one of hydroxyethyl cellulose and sodium polyacrylate.

[0017] Furthermore, the initiator includes at least one of potassium persulfate and ammonium persulfate.

[0018] A second aspect of the present invention provides a method for preparing the aforementioned styrene-butadiene latex, applicable to the preparation of the aforementioned styrene-butadiene latex, comprising the following steps: (1) Pre-emulsification: Mix styrene, butadiene, rosin glycerol ester, composite emulsifier, hydrophilic functional monomer with 80-120 parts of deionized water and pre-emulsify for 20-30 minutes; (2) Polymerization reaction: Under nitrogen protection, an initiator is added and the reaction is carried out at 70-80℃ for 6-8 hours; (3) Post-processing: Cool down to 40°C, add electrolyte, remaining deionized water and thickener, adjust pH to 8-9, filter, and obtain the finished product.

[0019] Further, in step (1), the stirring speed during mixing is 700 rpm to 800 rpm.

[0020] Furthermore, in step (2), after adding the initiator, the mixture is stirred at a speed of 80 rpm to 100 rpm.

[0021] Further, in step (3), after adding electrolyte, remaining deionized water and thickener, stirring is performed at a speed of 100rpm-200rpm; the filtration is performed using a 100-200 mesh stainless steel screen.

[0022] Compared with existing technologies, the above preparation method results in stronger interfacial stability, a more homogeneous system, and thus stronger mechanical properties and greater stability after repeated freeze-thaw cycles when preparing styrene-butadiene latex. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] In the prior art, when styrene-butadiene latex is frozen and then thawed, its adhesion decreases, its tensile strength decreases, and its stability deteriorates.

[0025] To overcome the above-mentioned defects, one aspect of the present invention provides a styrene-butadiene latex with high freeze-thaw stability. The styrene-butadiene latex comprises the following raw materials in parts by weight: 20-40 parts styrene, 60-80 parts butadiene, 10-15 parts rosin glycerol ester, 1-5 parts composite emulsifier, 1-3 parts hydrophilic functional monomer, 0.5-1 part electrolyte, 2-5 parts thickener, 0.6-1.5 parts initiator, and 150-200 parts deionized water.

[0026] For example, a styrene-butadiene latex with high freeze-thaw stability comprises the following raw materials by weight: 20 parts styrene, 60 parts butadiene, 10 parts rosin glycerol ester, 1 part composite emulsifier, 1 part hydrophilic functional monomer, 1 part electrolyte, 2 parts thickener, 0.6 parts initiator, and 150 parts deionized water.

[0027] For example, a styrene-butadiene latex with high freeze-thaw stability comprises the following raw materials by weight: 40 parts styrene, 80 parts butadiene, 15 parts rosin glycerol ester, 5 parts composite emulsifier, 3 parts hydrophilic functional monomer, 0.5 parts electrolyte, 5 parts thickener, 1.5 parts initiator, and 200 parts deionized water.

[0028] For example, a styrene-butadiene latex with high freeze-thaw stability comprises the following raw materials by weight: 30 parts styrene, 70 parts butadiene, 12 parts rosin glycerol ester, 3 parts composite emulsifier, 2 parts hydrophilic functional monomer, 0.8 parts electrolyte, 3 parts thickener, 1 part initiator, and 180 parts deionized water.

[0029] When the above technical solution is adopted, rosin glycerol ester, composite emulsifier, and hydrophilic functional monomer have a synergistic effect. When used in combination, they can significantly improve the mechanical properties of styrene-butadiene latex and enhance its freeze-thaw stability. Moreover, the composite emulsifier forms a double protective film on the surface of latex particles, and the electrolyte enhances the electrostatic repulsion between particles by adjusting the potential, preventing demulsification caused by intensified particle collisions during freeze-thaw cycles.

[0030] In some embodiments, the composite emulsifier is prepared by compounding sodium dodecylbenzenesulfonate and alkylphenol polyoxyethylene ether in a mass ratio of 1:1 to 1:3.

[0031] For example, the mass ratio of sodium dodecylbenzenesulfonate to alkylphenol polyoxyethylene ether can be specifically selected as a range of values ​​consisting of 1:1, 1:2, 1:3, or any point values, preferably 1:2 to 1:3.

[0032] When using the above technical solution, the polyoxyethylene chains of APEO encapsulate rosin glycerol ester molecules through hydrogen bonds, significantly reducing their dispersed particle size and ensuring uniform distribution at the latex particle interface. The charge repulsion of SDBS prevents rosin glycerol ester particles from agglomerating due to van der Waals forces, thereby improving the dispersion stability of the resin in the latex and further enhancing freeze-thaw stability.

[0033] In some embodiments, the hydrophilic functional monomer is composed of hydroxyethyl methacrylate and diallyl terephthalate in a mass ratio of 1:5.

[0034] When the above-mentioned specific mass ratio of hydrophilic functional monomers is used, the synergistic effect with rosin glycerol ester and composite emulsifier can be significantly enhanced, thereby improving the stability of the styrene-butadiene latex interface and thus improving freeze-thaw stability.

[0035] In some embodiments, the electrolyte includes at least one of sodium chloride and potassium chloride.

[0036] In some embodiments, the thickener includes at least one of hydroxyethyl cellulose and sodium polyacrylate.

[0037] In some embodiments, the initiator includes at least one of potassium persulfate and ammonium persulfate.

[0038] The second aspect of this invention provides a method for preparing styrene-butadiene latex, applicable to the preparation of styrene-butadiene latex, comprising the following steps: (1) Pre-emulsification: Mix styrene, butadiene, rosin glycerol ester, composite emulsifier, hydrophilic functional monomer with 80-120 parts of deionized water and pre-emulsify for 20-30 minutes; (2) Polymerization reaction: Under nitrogen protection, an initiator is added and the reaction is carried out at 70-80℃ for 6-8 hours; (3) Post-processing: Cool down to 40°C, add electrolyte, remaining deionized water and thickener, adjust pH to 8-9, filter, and obtain the finished product.

[0039] For example, the pre-emulsification time can be selected as a range of values ​​consisting of 20 min, 25 min, 30 min, or any point values, preferably 25 min-30 min.

[0040] In some embodiments, in step (1), the stirring speed during mixing is 700 rpm to 800 rpm.

[0041] For example, the stirring speed can be selected as a range of values ​​consisting of 700 rpm, 750 rpm, 800 rpm, or any point value, preferably 700 rpm to 750 rpm.

[0042] In some embodiments, in step (2), after adding the initiator, the mixture is stirred at a speed of 80 rpm to 100 rpm.

[0043] For example, the stirring speed is a range of values ​​consisting of 80 rpm, 90 rpm, 100 rpm, or any point value, preferably 90 rpm to 100 rpm.

[0044] In some embodiments, in step (3), after adding electrolyte, remaining deionized water and thickener, stirring is performed at a speed of 100 rpm to 200 rpm; filtration is performed using a 100-200 mesh stainless steel screen.

[0045] For example, the stirring speed can be selected as a range of values ​​consisting of 100 rpm, 150 rpm, 200 rpm, or any point value, preferably 100 rpm to 150 rpm.

[0046] When styrene-butadiene latex is prepared using the above method, the interfacial stability of the styrene-butadiene latex is stronger, the system is more homogeneous, and thus the mechanical properties are stronger, as well as the stability after repeated freeze-thaw cycles are stronger.

[0047] To better illustrate the technical solution of the present invention, the following embodiments are provided. It should be understood that, unless otherwise stated, all raw materials used in the embodiments are commercially available.

[0048] Example 1: A styrene-butadiene latex with high freeze-thaw stability comprises the following raw materials by weight: 20 parts styrene, 60 parts butadiene, 10 parts rosin glycerol ester, 1 part composite emulsifier, 1 part hydrophilic functional monomer, 0.5 parts sodium chloride, 2 parts hydroxyethyl cellulose, 0.6 parts potassium persulfate, and 150 parts deionized water; wherein the composite emulsifier is composed of sodium dodecylbenzenesulfonate and alkylphenol polyoxyethylene ether in a 1:1 mass ratio, and the hydrophilic functional monomer is composed of hydroxyethyl methacrylate and diallyl terephthalate in a 1:5 mass ratio.

[0049] The preparation process of the above-mentioned styrene-butadiene latex is as follows: (1) Pre-emulsification: Styrene, butadiene, rosin glycerol ester, composite emulsifier, hydrophilic functional monomer and 80 parts of deionized water are mixed and pre-emulsified at 800 rpm for 20 min; (2) Polymerization reaction: Under nitrogen protection, the initiator was added and stirred at 80 rpm, and the reaction was carried out at 70°C for 6 h; (3) Post-treatment: Cool down to 40°C, add sodium chloride, the remaining deionized water and hydroxyethyl cellulose, stir at 200 rpm until uniform, adjust pH to 8, filter, and obtain the finished product.

[0050] Example 2: A styrene-butadiene latex with high freeze-thaw stability comprises the following raw materials by weight: 40 parts styrene, 80 parts butadiene, 15 parts rosin glycerol ester, 5 parts composite emulsifier, 3 parts hydrophilic functional monomer, 1 part potassium chloride, 5 parts sodium polyacrylate, 1.5 parts ammonium persulfate, and 200 parts deionized water; wherein the composite emulsifier is a mixture of sodium dodecylbenzenesulfonate and alkylphenol polyoxyethylene ether in a mass ratio of 1:3, and the hydrophilic functional monomer is a mixture of hydroxyethyl methacrylate and diallyl terephthalate in a mass ratio of 1:5. The preparation process of the above styrene-butadiene latex is as follows: (1) Pre-emulsification: Styrene, butadiene, rosin glycerol ester, composite emulsifier, hydrophilic functional monomer and 120 parts of deionized water are mixed and pre-emulsified at 730 rpm for 25 min; (2) Polymerization reaction: Under nitrogen protection, ammonium persulfate was added and stirred at 90 rpm for 8 h at 80 °C; (3) Post-treatment: Cool down to 40°C, add calcium chloride, the remaining deionized water and sodium polyacrylate, stir at 100 rpm until uniform, adjust pH to 9, filter, and obtain the finished product.

[0051] Example 3: A styrene-butadiene latex with high freeze-thaw stability comprises the following raw materials in parts by weight: 30 parts styrene, 70 parts butadiene, 12 parts rosin glycerol ester, 3 parts composite emulsifier, 2 parts hydrophilic functional monomer, 0.8 parts sodium chloride, 3 parts hydroxyethyl cellulose, 1 part potassium persulfate, and 180 parts deionized water.

[0052] The composite emulsifier is composed of sodium dodecylbenzenesulfonate and alkylphenol polyoxyethylene ether in a mass ratio of 1:2, and the hydrophilic functional monomer is composed of hydroxyethyl methacrylate and diallyl terephthalate in a mass ratio of 1:5.

[0053] The preparation process of the above-mentioned styrene-butadiene latex is as follows: (1) Pre-emulsification: Styrene, butadiene, rosin glycerol ester, composite emulsifier, hydrophilic functional monomer and 100 parts of deionized water are mixed and pre-emulsified at 700 rpm for 20 min; (2) Polymerization reaction: Under nitrogen protection, potassium persulfate was added and stirred at 100 rpm, and the reaction was carried out at 75°C for 7 h; (3) Post-treatment: Cool down to 40°C, add sodium chloride, the remaining deionized water and hydroxyethyl cellulose, stir at 150 rpm until uniform, adjust pH to 8.2, filter, and obtain the finished product.

[0054] Comparative Example 1 Taking Example 3 as an example, the only difference from Example 3 is that glycidyl methacrylate is used to replace rosin glycerol ester, while other components and preparation process remain unchanged.

[0055] Comparative Example 2 Taking Example 3 as an example, the only difference from Example 3 is the removal of rosin glycerol ester and the increase of the weight of deionized water to 212 parts, while the other components and preparation process remain unchanged.

[0056] Comparative Example 3 Taking Example 3 as an example, the only difference from Example 3 is that rosin glycerol ester is removed, and the total weight of the composite emulsifier and hydrophilic functional monomer is increased to 17 parts, of which 7 parts are composite emulsifier and 10 parts are hydrophilic functional monomer, while other components and preparation process remain unchanged.

[0057] Comparative Example 4 Taking Example 3 as an example, the only difference from Example 3 is that sodium chloride is removed and the weight of the composite emulsifier is increased to 3.8 parts, while other components and preparation process remain unchanged.

[0058] Comparative Example 5 Taking Example 3 as an example, the only difference from Example 3 is that the hydrophilic functional monomer is replaced with a mixture of acrylic acid and methacrylic acid in a mass ratio of 1:2, while the other components and preparation process remain unchanged.

[0059] The performance of the styrene-butadiene latexes prepared in Examples 1 to 3 and Comparative Examples 1 to 5 was tested: The appearance, viscosity change rate, and solid content retention rate of styrene-butadiene latex were measured after being frozen at -20℃±2℃ for 24h and thawed at 23℃±2℃ for 24h, repeated 3-5 times. Particle size and zeta potential before and after freeze-thaw were also measured. The results are shown in Tables 1 and 2. Table 1 Performance Test Results

[0060] Table 2. Results of particle size and zeta potential measurements before and after freeze-thaw.

[0061] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. The solutions disclosed in the embodiments are described simply because they correspond to the methods disclosed in the embodiments; relevant parts can be found in the method section.

[0062] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A styrene-butadiene rubber latex with high freeze-thaw stability, characterized in that, The styrene-butadiene latex comprises the following raw materials by weight: 20-40 parts styrene, 60-80 parts butadiene, 10-15 parts rosin glyceryl ester, 1-5 parts composite emulsifier, 1-3 parts hydrophilic functional monomer, 0.5-1 part electrolyte, 2-5 parts thickener, 0.6-1.5 parts initiator, and 150-200 parts deionized water.

2. The styrene-butadiene latex with high freeze-thaw stability according to claim 1, characterized in that, The composite emulsifier is prepared by compounding sodium dodecylbenzenesulfonate and alkylphenol polyoxyethylene ether in a mass ratio of 1:1 to 1:

3.

3. The styrene-butadiene latex with high freeze-thaw stability according to claim 1, characterized in that, The hydrophilic functional monomer is composed of hydroxyethyl methacrylate and diallyl terephthalate in a mass ratio of 1:

5.

4. The styrene-butadiene latex with high freeze-thaw stability according to claim 1, characterized in that, The electrolyte includes at least one of sodium chloride and potassium chloride.

5. A styrene-butadiene latex with high freeze-thaw stability according to claim 1, characterized in that, The thickener includes at least one of hydroxyethyl cellulose and sodium polyacrylate.

6. A styrene-butadiene latex with high freeze-thaw stability according to claim 1, characterized in that, The initiator includes at least one of potassium persulfate and ammonium persulfate.

7. The method for preparing styrene-butadiene latex according to any one of claims 1-6, applied to the preparation of styrene-butadiene latex according to any one of claims 1-6, characterized in that, The process includes the following: (1) Pre-emulsification: Mix styrene, butadiene, rosin glycerol ester, composite emulsifier, hydrophilic functional monomer with 80-120 parts of deionized water and pre-emulsify for 20-30 minutes; (2) Polymerization reaction: Under nitrogen protection, an initiator is added and the reaction is carried out at 70-80℃ for 6-8 hours; (3) Post-processing: Cool down to 40°C, add electrolyte, remaining deionized water and thickener, adjust pH to 8-9, filter, and obtain the finished product.

8. The preparation method according to claim 7, characterized in that, In step (1), the stirring speed during mixing is 700 rpm to 800 rpm.

9. The preparation method according to claim 7, characterized in that, In step (2), after adding the initiator, stir at a speed of 80 rpm to 100 rpm.

10. The preparation method according to any one of claims 7-9, characterized in that, In step (3), after adding electrolyte, remaining deionized water and thickener, stir at a speed of 100 rpm to 200 rpm; the filtration is carried out using a 100-200 mesh stainless steel screen.

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