Anionic hydroxyl silicone oil emulsion and method for preparing the same

Abstract

This invention discloses an anionic hydroxyl silicone oil emulsion and its preparation method, relating to the field of polysiloxane emulsion technology, and belonging to patent classification number C08G77 / 04. The preparation method is as follows: Triethanolamine dodecylbenzenesulfonate salt, tridecyl alcohol polyether, and deionized water are mixed and dissolved, heated, and polydimethylsiloxane alcohol is added under high-speed shearing for homogenization. Water is added and the reaction is maintained at a constant temperature to obtain a basic emulsion. γ-(methacryloyloxy)propyltrimethoxysilane is added dropwise to react and obtain an interface-reinforced emulsion. Acrylamide, N-hydroxymethylacrylamide, etc., are pre-emulsified and then added to the interface-reinforced emulsion with ammonium persulfate under nitrogen protection. Polymerization forms a cross-linked polymer shell. After cooling, tert-butylhydroquinone and disodium ethylenediaminetetraacetate are added to obtain an antioxidant emulsion. Phenoxyethanol and octyl glycol are added to obtain the final emulsion. This method significantly improves the thermal stability of the emulsion through the synergistic effects of composite emulsification, interface reinforcement, shell protection, and antioxidant properties, making it suitable for high-temperature environments.

Description

Technical Field

[0001] This invention relates to the field of polysiloxane emulsion technology, belonging to patent classification number C08G77 / 04, specifically to an anionic hydroxyl silicone oil emulsion and its preparation method. Background Technology

[0002] Hydroxyl silicone oil emulsion is a homogeneous emulsion of polydimethylsiloxane with hydroxyl-terminated ends. Visually, it appears as a white, homogeneous emulsion free of mechanical impurities. Due to its unique molecular structure, hydroxyl silicone oil emulsion possesses numerous superior properties, playing a crucial role in the finishing of various textiles. It not only significantly improves fabric elasticity but also effectively enhances fabric hand feel, making the fabric softer and smoother. Furthermore, it is suitable for fabric finishing and sewing thread treatment, enhancing thread strength and toughness, preventing breakage, and increasing sewing speed. It can also be used as a release agent and mold release agent. In the demolding process of rubber, plastics, and other materials, it reduces friction between the material and the mold, making the demolding process smoother, improving production efficiency and product quality.

[0003] Silicone oil emulsions can be classified into several types based on the surfactants they use, including cationic, anionic, nonionic, and complex ionic emulsions. Among them, anionic hydroxyl silicone oil emulsions are highly favored. Anionic hydroxyl emulsions exhibit good compatibility in fabric finishing agents and are very stable. In textile printing and dyeing processes, most auxiliaries are anionic. If cationic hydroxyl emulsions are used, they often easily cause emulsion breaking and oil floating phenomena, while anionic hydroxyl emulsions can effectively avoid this drawback. Therefore, they are more popular with users in practical applications and have extremely wide applications. For example, in the textile printing and dyeing industry, using it for fabric finishing instantly makes cotton, linen, silk, and wool fabrics soft and smooth, enhances elasticity and abrasion resistance, and improves waterproof and heat resistance; in the thread manufacturing industry, it greatly increases the strength and toughness of high-speed sewing threads, reduces needle and thread breakage, and improves sewing efficiency; in the treatment of wigs, it makes them soft and shiny, and easier to comb; in the leather industry, it serves as an excellent release agent; and in the rubber and plastics industry, it serves as a highly efficient water-based release agent.

[0004] However, existing anionic hydroxyl silicone oil emulsions still have some shortcomings, the most prominent being poor thermal stability. Silicone oil emulsions are essentially thermodynamically unstable multiphase dispersion systems composed of silicone oil, emulsifiers, and water. Under normal conditions, the emulsifier reduces the interfacial tension between silicone oil and water, allowing the silicone oil to be uniformly dispersed in the water, forming a relatively stable emulsion. However, when the ambient temperature rises, the movement of water molecules in the emulsion intensifies, potentially disrupting the stable structure formed by the silicone oil and emulsifier, leading to emulsion demulsification, i.e., the separation of silicone oil and water. For example, in scenarios requiring high-temperature processing of materials, if the anionic hydroxyl silicone oil emulsion has poor stability, it cannot maintain good performance at high temperatures. In environments with temperatures between 120°C and 180°C, the emulsion may demulsify, preventing it from effectively providing softening and waterproofing properties in fabric finishing, and hindering smooth demolding, thus affecting product quality and production efficiency. Furthermore, demulsification may leave residues on equipment or mold surfaces, increasing cleaning difficulty and costs, and adversely impacting production. Summary of the Invention

[0005] The purpose of this invention is to provide an anionic hydroxyl silicone oil emulsion and its preparation method, thereby solving the technical problem of poor thermal stability of silicone oil emulsions mentioned in the background art. The anionic hydroxyl silicone oil emulsion prepared by this invention has good thermal stability and is suitable for use under harsh high-temperature environments.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for preparing an anionic hydroxyl silicone oil emulsion includes the following steps:

[0008] a) Mix triethanolamine dodecylbenzenesulfonate, tridecyl alcohol polyether and deionized water, stir to dissolve and heat, add polydimethylsiloxane alcohol under high-speed shearing for homogenization, then add deionized water and keep the reaction at a constant temperature to obtain the basic emulsion.

[0009] b) Add a mixture of γ-(methacryloyloxy)propyltrimethoxysilane and dibutyltin dilaurate to the base emulsion and react to obtain an interface-enhanced emulsion;

[0010] c) Acrylamide, N-hydroxymethylacrylamide, N,N'-methylenebisacrylamide and deionized water are mixed and pre-emulsified to obtain a monomer pre-emulsion. Under nitrogen protection, the monomer pre-emulsion and ammonium persulfate are slowly added to the interface-strengthened emulsion to carry out the polymerization reaction, forming a cross-linked polymer shell on the surface of the emulsion particles, and obtaining a polymer shell-protected emulsion.

[0011] d) After the temperature of the polymer shell protective emulsion drops below 40°C, add tert-butylhydroquinone and disodium ethylenediaminetetraacetate, stir and mix evenly to obtain an antioxidant emulsion;

[0012] e) Add phenoxyethanol and octyl glycol to the antioxidant emulsion, stir well, and then add triethanolamine aqueous solution dropwise to adjust the pH to obtain anionic hydroxy silicone oil emulsion.

[0013] In this invention, the base emulsion uses a composite emulsification system composed of triethanolamine dodecylbenzenesulfonate (anionic) and tridecyl alcohol polyether (nonionic). The electrostatic repulsion of the anionic emulsifier and the steric hindrance effect of the nonionic emulsifier jointly construct a stable interface structure for the base emulsion, effectively preventing the aggregation and fusion of latex particles at high temperatures. This invention achieves thermal stability of the base emulsion through a triple mechanism: First, interface strengthening is achieved through the bonding of γ-(methacryloyloxy)propyltrimethoxysilane with hydroxyl silicone oil. γ-(methacryloyloxy)propyltrimethoxysilane undergoes hydrolysis under the catalysis of dibutyltin dilaurate, generating reactive silanol groups. These silanol groups undergo a directional condensation reaction with the silanol groups at the ends of the hydroxyl silicone oil molecules, forming stable covalent siloxane bonds. This process forms a covalently bonded organosilicon hybrid layer at the oil-water interface of latex particles, significantly reducing interfacial energy, increasing interfacial film strength and elastic modulus, and enhancing resistance to deformation at high temperatures. This effectively suppresses latex particle collision and aggregation caused by intensified Brownian motion. Simultaneously, it significantly reduces the Ostwald ripening effect, ensuring the emulsion maintains stable particle size distribution at high temperatures. Secondly, acrylamide and N-hydroxymethylacrylamide, under the action of the crosslinking agent N,N'-methylenebisacrylamide, undergo a free radical polymerization reaction initiated by ammonium persulfate. This process grafts and copolymerizes on the surface of latex particles with reactive double bonds (double bonds on silane coupling agents), forming a polymer shell with a three-dimensional network structure and a high glass transition temperature. This ensures the shell maintains a rigid structure at high temperatures, effectively blocking the thermal motion and escape of the core silicone oil molecules. Furthermore, the formed hydrogen bond network effectively dissipates heat stress, preventing shell cracking and providing physical protection for the core. Finally, the thermo-oxidative degradation reaction of silicone oil polymer chains is inhibited through antioxidant effects. Specifically, tert-butylhydroquinone acts as a free radical scavenger to quench the active free radicals generated by thermo-oxidation, and disodium ethylenediaminetetraacetate cuts off the metal-catalyzed oxidation pathway by chelating transition metal ions. Through the above actions, the thermo-oxidative degradation reaction of hydroxyl silicone oil polymer chains can be effectively inhibited, thereby further improving the thermal stability of silicone oil emulsions.

[0014] Preferably, in step a), the mass ratio of triethanolamine dodecylbenzenesulfonate to tridecyl alcohol polyether is 6:1 to 4.

[0015] Preferably, in step a), the heat preservation reaction temperature is 75-80°C and the reaction time is 2-3 hours.

[0016] Preferably, in step b), the mass ratio of γ-(methacryloyloxy)propyltrimethoxysilane to dibutyltin dilaurate is 10:0.5 to 1.5.

[0017] Preferably, in step c), the mass ratio of acrylamide to N-hydroxymethylacrylamide is 10:2 to 5.

[0018] Preferably, in step c), octadecyl methacrylate is also added to the monomer preemulsion.

[0019] In the technical solution of this invention, as described above, acrylamide and N-hydroxymethylacrylamide are grafted and copolymerized on the surface of latex particles to form a polymer shell with a three-dimensional network structure, thereby improving the thermal stability of the emulsion. However, after in-depth research, the research team found that the subsequently added tert-butylhydroquinone oil-soluble antioxidant was blocked outside the polymer shell and confined in the hydrophilic polymer network, unable to effectively migrate to the hydrophobic silicone oil core region, thus affecting the full effectiveness of the main antioxidant tert-butylhydroquinone. To further solve this problem, this invention introduces octadecyl methacrylate into the polymer shell. Its long-chain alkyl groups spontaneously align during polymerization according to the principle of like dissolves like, forming continuous hydrophobic microchannels in the hydrophilic polyacrylamide crosslinking network. These microchannels provide a directional migration path for the oil-soluble antioxidant tert-butylhydroquinone molecules, enabling them to efficiently penetrate the polymer shell barrier and rapidly diffuse to the silicone oil core, thereby solving the problem of local failure of the antioxidant due to steric hindrance and significantly improving the utilization efficiency and overall thermal-oxidative stability of the antioxidant system.

[0020] Preferably, the amount of octadecyl methacrylate added is 1 to 5 wt% of the total mass of acrylamide and N-hydroxymethylacrylamide.

[0021] Preferably, in step d), the mass ratio of tert-butylhydroquinone to disodium ethylenediaminetetraacetate is 3:1 to 2.

[0022] Preferably, in step e), the mass ratio of phenoxyethanol to octanelyl glycol is 8:3 to 5.

[0023] An anionic hydroxyl silicone oil emulsion is prepared by the method described above.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] 1. A composite emulsion system using anionic triethanolamine dodecylbenzenesulfonate and nonionic tridecyl alcohol polyether is adopted. Through electrostatic repulsion and steric hindrance, a stable basic emulsion interface is constructed, which effectively prevents the aggregation and fusion of latex particles under high temperature conditions, thus providing a basis for the thermal stability of the emulsion.

[0026] 2. An organosilicon hybrid layer is formed through the bonding reaction of γ-(methacryloyloxy)propyltrimethoxysilane and hydroxyl silicone oil, which reduces the interfacial energy, improves the interfacial film strength and elastic modulus, and inhibits latex particle collision aggregation and Ostwald curing. At the same time, acrylamide monomers polymerize on the surface of latex particles to form a three-dimensional network polymer shell. Its high glass transition temperature ensures high-temperature rigidity, which can prevent silicone oil from escaping. In addition, the hydrogen bond network dissipates heat and stress, preventing the shell from cracking.

[0027] 3. By capturing thermally oxidized free radicals with tert-butylhydroquinone and chelating transition metal ions with disodium ethylenediaminetetraacetate to cut off the catalytic oxidation pathway, the thermal-oxidative degradation of hydroxyl silicone oil chains is directly inhibited. At the same time, octadecyl methacrylate is introduced to form hydrophobic microchannels in the polymer shell, which helps oil-soluble antioxidants migrate efficiently to the silicone oil core, solves the problem of local failure caused by steric hindrance, and significantly improves antioxidant efficiency and overall thermal stability. Detailed Implementation

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] Example 1

[0030] A method for preparing an anionic hydroxyl silicone oil emulsion includes the following steps:

[0031] Step 1: Add 6.0 g of triethanolamine dodecylbenzenesulfonate, 3.0 g of tridecyl alcohol polyether-12, and 60 mL of deionized water to a four-necked flask equipped with a mechanical stirrer, thermometer, and condenser. Stir at 300 rpm and heat to 75°C until completely dissolved. Then, turn on a high-speed shear emulsifier (5000 rpm) and slowly add 100 g of hydroxyl-terminated polydimethylsiloxane alcohol (viscosity 5000 mPa·s). Homogenize for 20 minutes to form a primary emulsion. After adding 32 mL of deionized water, reduce the stirring speed to 300 rpm and react at 78°C for 2.5 hours to obtain a basic emulsion with uniform particles.

[0032] Step 2: 1.5g of γ-(methacryloyloxy)propyltrimethoxysilane and 0.15g of dibutyltin dilaurate were premixed and added dropwise to the base emulsion (temperature 80℃) at a rate of 1 drop / second through a constant pressure dropping funnel, completing the addition within 30 minutes. The reaction was then maintained at 80℃ for 1.5 hours to allow the silane coupling agent to fully condense with the silanol groups on the silicone oil surface, forming an interface-strengthened emulsion.

[0033] Step 3: Mix 8.0g acrylamide, 3.0g N-hydroxymethylacrylamide, octadecyl methacrylate (4wt% of the total mass of acrylamide and N-hydroxymethylacrylamide), 0.1g N,N'-methylenebisacrylamide, and 20mL deionized water, and sonicate for 5 minutes to prepare a pre-emulsion. Purge the interfacial strengthening emulsion (60℃) with nitrogen for protection. While stirring at 200rpm, slowly add the pre-emulsion and 0.3g ammonium persulfate (dissolved in 10mL water) dropwise through a double dropping funnel, controlling the addition to complete over 2 hours. Then continue the reaction at 60℃ for 1 hour to complete interfacial polymerization and form a core-shell emulsion.

[0034] Step 4: Stop heating and allow the emulsion to cool naturally to below 40°C. Add 0.3g tert-butylhydroquinone and 0.18g disodium ethylenediaminetetraacetate. Stir at 300 rpm for 30 minutes to ensure that the antioxidant is fully and evenly dispersed, and obtain an antioxidant emulsion.

[0035] Step 5: Add 0.8g phenoxyethanol and 0.45g octyl glycol to the emulsion and stir for 20 minutes to achieve the preservative function. Finally, slowly adjust the pH to the range of 7.5-8.0 with a 5wt% triethanolamine aqueous solution, and filter through a 200-mesh sieve to obtain anionic hydroxyl silicone oil emulsion.

[0036] Example 2

[0037] A method for preparing an anionic hydroxyl silicone oil emulsion includes the following steps:

[0038] Step 1: Add 6.0 g of triethanolamine dodecylbenzenesulfonate, 2.0 g of tridecyl alcohol polyether-12, and 60 mL of deionized water to a four-necked flask equipped with a mechanical stirrer, thermometer, and condenser. Stir at 300 rpm and heat to 75°C until completely dissolved. Then, turn on a high-speed shear emulsifier (5000 rpm) and slowly add 100 g of hydroxyl-terminated polydimethylsiloxane alcohol (viscosity 5000 mPa·s). Homogenize for 20 minutes to form a primary emulsion. After adding 32 mL of deionized water, reduce the stirring speed to 300 rpm and react at 78°C for 2.5 hours to obtain a basic emulsion with uniform particles.

[0039] Step 2: 1.5g of γ-(methacryloyloxy)propyltrimethoxysilane and 0.09g of dibutyltin dilaurate were premixed and added dropwise to the base emulsion (temperature 80℃) at a rate of 1 drop / second through a constant pressure dropping funnel, completing the addition within 30 minutes. The reaction was then maintained at 80℃ for 1.5 hours to allow the silane coupling agent to fully condense with the silanol groups on the silicone oil surface, forming an interface-strengthened emulsion.

[0040] Step 3: Mix 8.0g acrylamide, 2.0g N-hydroxymethylacrylamide, octadecyl methacrylate (2wt% of the total mass of acrylamide and N-hydroxymethylacrylamide), 0.1g N,N'-methylenebisacrylamide, and 20mL deionized water, and sonicate for 5 minutes to prepare a pre-emulsion. Purge the interfacial strengthening emulsion (60℃) with nitrogen for protection. While stirring at 200rpm, slowly add the pre-emulsion and 0.3g ammonium persulfate (dissolved in 10mL water) dropwise through a double dropping funnel, controlling the addition to complete over 2 hours. Then continue the reaction at 60℃ for 1 hour to complete interfacial polymerization and form a core-shell emulsion.

[0041] Step 4: Stop heating and allow the emulsion to cool naturally to below 40°C. Add 0.3g tert-butylhydroquinone and 0.12g disodium ethylenediaminetetraacetate, and stir at 300 rpm for 30 minutes to ensure that the antioxidant is fully and evenly dispersed to obtain an antioxidant emulsion.

[0042] Step 5: Add 0.8g phenoxyethanol and 0.35g octyl glycol to the emulsion and stir for 20 minutes to achieve the preservative function. Finally, slowly adjust the pH to the range of 7.5-8.0 with a 5wt% triethanolamine aqueous solution, and filter through a 200-mesh sieve to obtain anionic hydroxyl silicone oil emulsion.

[0043] Example 3

[0044] A method for preparing an anionic hydroxyl silicone oil emulsion includes the following steps:

[0045] Step 1: Add 6.0 g of triethanolamine dodecylbenzenesulfonate, 2.5 g of tridecyl alcohol polyether-12, and 60 mL of deionized water to a four-necked flask equipped with a mechanical stirrer, thermometer, and condenser. Stir at 300 rpm and heat to 75°C until completely dissolved. Then, turn on a high-speed shear emulsifier (5000 rpm) and slowly add 100 g of hydroxyl-terminated polydimethylsiloxane alcohol (viscosity 5000 mPa·s). Homogenize for 20 minutes to form a primary emulsion. After adding 32 mL of deionized water, reduce the stirring speed to 300 rpm and react at 78°C for 2.5 hours to obtain a basic emulsion with uniform particles.

[0046] Step 2: 1.5g of γ-(methacryloyloxy)propyltrimethoxysilane and 0.10g of dibutyltin dilaurate were premixed and added dropwise to the base emulsion (temperature 80℃) at a rate of 1 drop / second through a constant pressure dropping funnel, completing the addition within 30 minutes. The reaction was then maintained at 80℃ for 1.5 hours to allow the silane coupling agent to fully condense with the silanol groups on the silicone oil surface, forming an interface-strengthened emulsion.

[0047] Step 3: Mix 8.0g acrylamide, 3.0g N-hydroxymethylacrylamide, octadecyl methacrylate (3.5wt% of the total mass of acrylamide and N-hydroxymethylacrylamide), 0.1g N,N'-methylenebisacrylamide, and 20mL deionized water, and sonicate for 5 minutes to prepare a pre-emulsion. Purge the interfacial strengthening emulsion (60℃) with nitrogen for protection. While stirring at 200rpm, slowly add the pre-emulsion and 0.3g ammonium persulfate (dissolved in 10mL water) dropwise through a double dropping funnel, controlling the addition to complete over 2 hours. Then continue the reaction at 60℃ for 1 hour to complete interfacial polymerization and form a core-shell emulsion.

[0048] Step 4: Stop heating and allow the emulsion to cool naturally to below 40°C. Add 0.3g tert-butylhydroquinone and 0.15g disodium ethylenediaminetetraacetate. Stir at 300 rpm for 30 minutes to ensure that the antioxidant is fully and evenly dispersed, and obtain an antioxidant emulsion.

[0049] Step 5: Add 0.8g phenoxyethanol and 0.4g octyl glycol to the emulsion and stir for 20 minutes to achieve the preservative function. Finally, slowly adjust the pH to the range of 7.5-8.0 with a 5wt% triethanolamine aqueous solution, and filter through a 200-mesh sieve to obtain anionic hydroxyl silicone oil emulsion.

[0050] Example 4

[0051] A method for preparing an anionic hydroxyl silicone oil emulsion includes the following steps:

[0052] Step 1: Add 6.0 g of triethanolamine dodecylbenzenesulfonate, 4.0 g of tridecyl alcohol polyether-12, and 60 mL of deionized water to a four-necked flask equipped with a mechanical stirrer, thermometer, and condenser. Stir at 300 rpm and heat to 75°C until completely dissolved. Then, turn on a high-speed shear emulsifier (5000 rpm) and slowly add 100 g of hydroxyl-terminated polydimethylsiloxane alcohol (viscosity 5000 mPa·s). Homogenize for 20 minutes to form a primary emulsion. After adding 32 mL of deionized water, reduce the stirring speed to 300 rpm and react at 80°C for 3 hours to obtain a basic emulsion with uniform particles.

[0053] Step 2: 1.5g of γ-(methacryloyloxy)propyltrimethoxysilane and 0.225g of dibutyltin dilaurate were premixed and added dropwise to the base emulsion (temperature 80℃) at a rate of 1 drop / second through a constant pressure dropping funnel, completing the addition within 30 minutes. The reaction was then maintained at 80℃ for 1.5 hours to allow the silane coupling agent to fully condense with the silanol groups on the silicone oil surface, forming an interface-strengthened emulsion.

[0054] Step 3: Mix 8.0g acrylamide, 4.0g N-hydroxymethylacrylamide, octadecyl methacrylate (5wt% of the total mass of acrylamide and N-hydroxymethylacrylamide), 0.1g N,N'-methylenebisacrylamide, and 20mL deionized water, and sonicate for 5 minutes to prepare a pre-emulsion. Purge the interfacial strengthening emulsion (60℃) with nitrogen for protection. While stirring at 200rpm, slowly add the pre-emulsion and 0.3g ammonium persulfate (dissolved in 10mL water) dropwise through a double dropping funnel, controlling the addition to complete over 2 hours. Then continue the reaction at 60℃ for 1 hour to complete interfacial polymerization and form a core-shell emulsion.

[0055] Step 4: Stop heating and allow the emulsion to cool naturally to below 40°C. Add 0.3g tert-butylhydroquinone and 0.2g disodium ethylenediaminetetraacetate, and stir at 300 rpm for 30 minutes to ensure that the antioxidant is fully and evenly dispersed to obtain an antioxidant emulsion.

[0056] Step 5: Add 0.8g phenoxyethanol and 0.5g octyl glycol to the emulsion and stir for 20 minutes to achieve the preservative function. Finally, slowly adjust the pH to the range of 7.5-8.0 with a 5wt% triethanolamine aqueous solution, and filter through a 200-mesh sieve to obtain anionic hydroxyl silicone oil emulsion.

[0057] Example 5

[0058] A method for preparing an anionic hydroxyl silicone oil emulsion includes the following steps:

[0059] Step 1: Add 6.0 g of triethanolamine dodecylbenzenesulfonate, 1.0 g of tridecyl alcohol polyether-12, and 60 mL of deionized water to a four-necked flask equipped with a mechanical stirrer, thermometer, and condenser. Stir at 300 rpm and heat to 75°C until completely dissolved. Then, turn on a high-speed shear emulsifier (5000 rpm) and slowly add 100 g of hydroxyl-terminated polydimethylsiloxane alcohol (viscosity 5000 mPa·s). Homogenize for 20 minutes to form a primary emulsion. After adding 32 mL of deionized water, reduce the stirring speed to 300 rpm and react at 75°C for 2 hours to obtain a basic emulsion with uniform particles.

[0060] Step 2: 1.5g of γ-(methacryloyloxy)propyltrimethoxysilane and 0.075g of dibutyltin dilaurate were premixed and added dropwise to the base emulsion (temperature 80℃) at a rate of 1 drop / second through a constant pressure dropping funnel, completing the addition within 30 minutes. The reaction was then maintained at 80℃ for 1.5 hours to allow the silane coupling agent to fully condense with the silanol groups on the silicone oil surface, forming an interface-strengthened emulsion.

[0061] Step 3: Mix 8.0g acrylamide, 1.6g N-hydroxymethylacrylamide, octadecyl methacrylate (1wt% of the total mass of acrylamide and N-hydroxymethylacrylamide), and 0.1g N,N'-methylenebisacrylamide with 20mL of deionized water, and sonicate for 5 minutes to prepare a pre-emulsion. Purge the interfacial strengthening emulsion (60℃) with nitrogen for protection. While stirring at 200rpm, slowly add the pre-emulsion and 0.3g ammonium persulfate (dissolved in 10mL water) dropwise through a double dropping funnel, controlling the addition to complete over 2 hours. Then continue the reaction at 60℃ for 1 hour to complete interfacial polymerization and form a core-shell emulsion.

[0062] Step 4: Stop heating and allow the emulsion to cool naturally to below 40°C. Add 0.3g tert-butylhydroquinone and 0.1g disodium ethylenediaminetetraacetate, and stir at 300 rpm for 30 minutes to ensure that the antioxidants are fully and evenly dispersed to obtain an antioxidant emulsion.

[0063] Step 5: Add 0.8g phenoxyethanol and 0.3g octyl glycol to the emulsion and stir for 20 minutes to achieve the preservative function. Finally, slowly adjust the pH to the range of 7.5-8.0 with a 5wt% triethanolamine aqueous solution, and filter through a 200-mesh sieve to obtain anionic hydroxyl silicone oil emulsion.

[0064] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that step 2 is omitted.

[0065] Comparative Example 2: The difference between Comparative Example 2 and Example 1 is that step 3 is omitted.

[0066] Comparative Example 3: The difference between Comparative Example 3 and Example 1 is that octadecyl methacrylate is not added in step 3.

[0067] Comparative Example 4: The difference between Comparative Example 4 and Example 1 is that step 4 is omitted.

[0068] Performance testing:

[0069] 1. Thermal stability test: 50 mL of the emulsion to be tested was placed into a stoppered glass centrifuge tube, sealed, and placed in a precision constant temperature oven at 120℃, 150℃, and 180℃ (temperature fluctuation ≤ ±1℃). The state was observed every 2 hours, and the time when the first layering, oil floating, or demulsification occurred was recorded; if no abnormalities were observed within 24 hours, it was recorded as "≥24h". Each temperature condition was tested in parallel 3 times, and the average value was taken as the result. The test results are shown in Table 1.

[0070] Table 1:

[0071]

[0072] 2. Centrifugation stability test: 10 mL of the emulsion was injected into a graduated centrifuge tube and centrifuged at 3000 rpm (accuracy ±50 rpm) for 30 minutes. After standing to room temperature, the layering was observed. Evaluation was based on three levels: "no layering (uniform and without layering), slight layering (supernatant ≤5%)," and "severe layering (supernatant >5% or oil clumping)." The test was performed in triplicate, and the majority result was used as the final evaluation. The test results are shown in Table 2.

[0073] 3. Particle size distribution stability test: A laser particle size analyzer (0.1-1000μm, accuracy ≤±2%) was used. The emulsion was diluted 100 times with deionized water and ultrasonically dispersed for 2 minutes (300W, 40kHz). The initial particle size distribution and the particle size distribution after being kept at 150℃ for 24 hours were measured, and the coefficient of variation (CV = standard deviation / average particle size × 100%) was calculated. Each sample was tested in triplicate, and the average value was taken. The smaller the CV value, the more stable the particle size distribution. The test results are shown in Table 2.

[0074] 4. Viscosity Retention Rate Test under Thermo-Oxidative Degradation: The initial viscosity (η0) of the emulsion was measured at 60 rpm using a rotational viscometer (1-10000 mPa·s, accuracy ±1%) in a 25℃ constant temperature water bath (±0.1℃). After the emulsion was placed in a 150℃ oven for 24 hours, it was cooled to 25℃ and the viscosity after aging (η1) was measured. The viscosity retention rate (%) was calculated using the formula "Viscosity retention rate (%) = (η1 / η0) × 100%". Three parallel tests were performed, and the average value was taken. The higher the value, the stronger the resistance to thermo-oxidative degradation. The test results are shown in Table 2.

[0075] Table 2:

[0076]

[0077] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing an anionic hydroxyl silicone oil emulsion, characterized in that, Includes the following steps: a) Mix triethanolamine dodecylbenzenesulfonate, tridecyl alcohol polyether and deionized water. The mass ratio of triethanolamine dodecylbenzenesulfonate to tridecyl alcohol polyether is 6:1 to 4. After stirring to dissolve and heating, add polydimethylsiloxane alcohol under high-speed shearing for homogenization. Then add deionized water and keep the reaction at a constant temperature to obtain the basic emulsion. b) A mixture of γ-(methacryloyloxy)propyltrimethoxysilane and dibutyltin dilaurate is added dropwise to the base emulsion for reaction. The mass ratio of γ-(methacryloyloxy)propyltrimethoxysilane to dibutyltin dilaurate is 10:0.5 to 1.5 to obtain an interface-enhanced emulsion. c) Acrylamide, N-hydroxymethylacrylamide, N,N'-methylenebisacrylamide, octadecyl methacrylate and deionized water are mixed and pre-emulsified. The mass ratio of acrylamide to N-hydroxymethylacrylamide is 10:2-5, and the amount of octadecyl methacrylate added is 1-5 wt% of the total mass of acrylamide and N-hydroxymethylacrylamide. A monomer pre-emulsion is obtained. Under nitrogen protection, the monomer pre-emulsion and ammonium persulfate are slowly added to the interface-strengthened emulsion to carry out the polymerization reaction. A cross-linked polymer shell is formed on the surface of the emulsion particles to obtain a polymer shell-protected emulsion. d) After the temperature of the polymer shell protective emulsion drops below 40°C, add tert-butylhydroquinone and disodium ethylenediaminetetraacetate. The mass ratio of tert-butylhydroquinone to disodium ethylenediaminetetraacetate is 3:1 to 2. Stir and mix evenly to obtain an antioxidant emulsion. e) Add phenoxyethanol and octyl glycol to the antioxidant emulsion, with a mass ratio of phenoxyethanol to octyl glycol of 8:3 to 5, stir evenly, and then add triethanolamine aqueous solution dropwise to adjust the pH to obtain anionic hydroxy silicone oil emulsion.

2. The method for preparing an anionic hydroxyl silicone oil emulsion according to claim 1, characterized in that, In step a), the heat preservation reaction temperature is 75-80℃, and the reaction time is 2-3h.

3. An anionic hydroxyl silicone oil emulsion, characterized in that, It is obtained by the preparation method described in claim 1 or 2.

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