A method for preparing organosilicon phosphate surfactants by trimethylsilyl phosphate method

Abstract

The application belongs to the technical field of organic silicon surfactant synthesis, and particularly relates to a method for preparing an organic silicon phosphate surfactant by a trimethyl silicon phosphate method. The method mixes single-end hydroxyl polyether modified siloxane with a water content of not more than 0.05% and trimethyl silicon phosphate, carries out phosphate esterification under dry nitrogen protection, and continuously condenses and removes trimethyl silanol, hexamethyl disiloxane and a small amount of water; after the reaction, a water-containing organic base is added to carry out controlled hydrolysis and neutralization, and then the product is obtained through pressure reduction and filtration. The application has mild reaction conditions, can reduce hydrolysis and rupture of the siloxane segment, improve the hydroxyl conversion rate, the molecular weight retention rate and the heat storage and emulsification stability of the product.

Description

Technical Field

[0001] This invention belongs to the field of organosilicon surfactant synthesis technology, and particularly relates to a method for preparing organosilicon phosphate surfactants using the trimethylsilyl phosphate method. Background Technology

[0002] Organosilicon phosphate surfactants are a class of organosilicon functional materials whose molecules simultaneously contain siloxane segments, hydrophilic polyether segments, and phosphate groups. The siloxane segments possess low surface energy and good spreading properties, the polyether segments improve the hydrophilicity, wettability, and emulsifying properties of the material, and the phosphate groups impart antistatic properties, electrolyte resistance, and interfacial adsorption capabilities. Therefore, organosilicon phosphate surfactants can be applied in textile auxiliaries, water-based coatings, daily chemical products, pesticide adjuvants, and oilfield chemicals.

[0003] Existing organosilicon phosphates are typically made from hydroxyl-containing polyether-modified siloxanes, with phosphate groups introduced via phosphorylation reagents such as phosphorus pentoxide, polyphosphoric acid, phosphoryl halides, or phosphoric acid. Different phosphorylation reagents exhibit significant differences in reactivity, selectivity for mono- and diesters, impact on the siloxane backbone, and post-processing methods.

[0004] Patent document US5070171A discloses a class of phosphorylated organosilicon polymers and their preparation methods. This document reacts organosilicon polymers containing polyether hydroxyl groups with polyphosphoric acid or phosphorus pentoxide to introduce phosphate ester groups onto the side chains of the organosilicon polymer. After the reaction, the polymer is neutralized to near neutrality using alkaline solutions such as sodium hydroxide, potassium hydroxide, or ammonium hydroxide. The document also points out that polyphosphoric acid is more conducive to the formation of more monophosphate esters, while phosphorus pentoxide has a stronger phosphorylation ability and readily forms more diester phosphate esters. This method can obtain organosilicon phosphate esters with antistatic and fiber lubricating properties, but both polyphosphoric acid and phosphorus pentoxide create a strongly acidic environment in the reaction system; phosphorus pentoxide is highly hygroscopic, and the reaction becomes more vigorous after the addition of hydroxyl-containing materials, making it difficult to uniformly control the exothermic reaction and viscosity. For raw materials containing long siloxane segments, the presence of acidic media alongside the raw materials or water generated in the reaction may also affect the stability of the siloxane segments. At the same time, the proportions of monoesters, diesters, and unreacted phosphates can easily change with the amount of feed, moisture content, and mass transfer state, which is not conducive to stable control of product composition.

[0005] Patent document EP0659804A1 discloses a phosphate ester-modified organopolysiloxane and its preparation method. The method involves reacting an organopolysiloxane containing alcohol hydroxyl groups with phosphorus halides such as phosphorus oxychloride, followed by hydrolysis of the phosphorus-halogen bond and alkali neutralization to obtain the phosphate ester-modified organopolysiloxane. This method can introduce phosphate ester groups into organopolysiloxanes and yield products with emulsifying properties and compatibility with polar media. However, phosphorus oxychloride has strong reactivity and corrosiveness, and the reaction usually needs to be carried out in organic solvents at low temperatures, with the addition of tertiary amine acid-binding agents to control the reaction. After the reaction, an alkaline aqueous solution is added for hydrolysis, and purification is completed through steps such as extraction, phase separation, water washing, and solvent removal under reduced pressure. This process easily generates halide-containing wastewater and organic solvent discharge, resulting in a long process flow and high requirements for equipment corrosion resistance and process control.

[0006] Furthermore, when using orthophosphoric acid to directly esterify hydroxyl-containing organosilicon compounds, the relatively low esterification reactivity of orthophosphoric acid typically necessitates increasing the reaction temperature or extending the reaction time. Additionally, the water generated during esterification restricts the shift of the reaction equilibrium towards the product. If the water is not removed promptly under acidic conditions, it may exacerbate the hydrolysis of the siloxane chain. Therefore, traditional methods struggle to simultaneously achieve phosphorylation reaction efficiency, siloxane backbone stability, product structural uniformity, and the green requirements of industrial production.

[0007] In summary, while existing technologies can prepare organosilicon phosphates with different structures, they still suffer from problems such as a highly acidic phosphorylation reaction system, difficulty in controlling water content and exothermic reactions, insufficient stability of siloxane segments, fluctuations in the mono- and diester ratios, cumbersome post-processing steps, and large emissions of waste salts, wastewater, or organic solvents. Therefore, it is necessary to develop a method for preparing organosilicon phosphate surfactants that offers mild reaction conditions, reduces the use of strongly acidic phosphorus sources and halogenated phosphorylation reagents, maintains siloxane segment stability, and facilitates improved phosphorylation conversion and product structural uniformity. Summary of the Invention

[0008] The purpose of this invention is to provide a method for preparing organosilicon phosphate surfactants using trimethylsilyl phosphate. The method uses tri(trimethylsilyl) phosphate as a phosphorylating agent and achieves directional phosphorylation of siloxanes modified with single-terminated hydroxyl polyethers, simultaneous removal of reaction byproducts, and hydrolysis and neutralization of residual silyl phosphate groups. This solves the problems of strong acidity in the reaction system, easy breakage of siloxane segments, poor product structural uniformity, and cumbersome post-processing in existing preparation methods.

[0009] Firstly, in order to achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0010] A method for preparing organosilicon phosphate surfactants via a trimethylsilyl phosphate method, the method comprising the following steps:

[0011] 1) A hydroxyl-terminated polyether-modified siloxane is mixed with tris(trimethylsilyl)phosphate, such that the molar ratio of the hydroxyl groups in the hydroxyl-terminated polyether-modified siloxane to the tris(trimethylsilyl)phosphate is 1.2–1.3:1. The mixture is reacted at 60–80°C for 2–4 hours under dry nitrogen protection. Dry nitrogen is continuously introduced during the reaction, and the reaction tail gas is collected by condensation to continuously remove the trimethylsilanol generated in the reaction, the hexamethyldisiloxane generated by the condensation of trimethylsilanol, and the water generated by the condensation. The hydroxyl-terminated polyether-modified siloxane contains one polyether-terminal carbon hydroxyl group and does not contain any silanol groups.

[0012] 2) Cool the reactants obtained in step 1) to 10-40°C, add an aqueous organic base, hydrolyze the P-O-Si(CH3)3 groups that are not substituted by the terminal carbon hydroxyl groups of the polyether to form phosphate hydroxyl groups, and make at least some of the phosphate hydroxyl groups form phosphate ester salts with the organic base, and adjust the pH of the 10w% aqueous solution of the obtained product at 25°C to 6.5-7.5.

[0013] 3) The reactants obtained in step 2) are heated to 100-120°C for vacuum devolatilization to remove water, trimethylsilanol and hexamethyldisiloxane, and then filtered to obtain the organosilicon phosphate surfactant.

[0014] As a further improvement, the single-terminated hydroxyl polyether modified siloxane described in step 1) has a moisture content of no more than 0.05 w and provides tris(trimethylsilyl)phosphate with a purity of no less than 98.5 w%.

[0015] As a further improvement, the single-hydroxyl-terminated polyether modified siloxane is selected from at least one of single-hydroxyl-terminated polyether modified trisiloxane and single-hydroxyl-terminated polyether modified polydimethylsiloxane.

[0016] As a further improvement, the number-average molecular weight of the single-hydroxyl-terminated polyether-modified siloxane described in step 1) is 600–2000 g / mol, and the dynamic viscosity at 25°C is 20–1000 mPa·s.

[0017] As a further improvement, in step 1), no organic solvent or esterification catalyst is added to the reaction, and tris(trimethylsilyl)phosphate is directly dispersed or dissolved in the single-terminated hydroxyl polyether modified siloxane to form a homogeneous reaction system.

[0018] As a further improvement, in step 1), dry nitrogen gas is continuously introduced during the reaction process, and the reaction tail gas is collected by condensation to continuously remove the trimethylsilanol generated in the reaction, the hexamethyldisiloxane generated by the condensation of trimethylsilanol, and the water generated by the condensation.

[0019] As a further improvement, in step 1), dry nitrogen gas is introduced from below the surface of the reaction liquid during the reaction process, and a condenser and a receiving device are connected in sequence to the gas phase outlet of the reaction vessel to collect trimethylsilanol and hexamethyldisiloxane while the reaction is in progress.

[0020] As a further improvement, the organic base in the aqueous organic base is selected from at least one of triethanolamine, triethylamine, dimethylethanolamine, monoisopropanolamine, diisopropanolamine, and tert-butanolamine.

[0021] As a further improvement, step 2) includes: adding the aqueous organic base dropwise at 10–40°C, and continuing to stir for 1–4 hours after the addition is complete, so that the residual P—O—Si(CH3)3 groups are hydrolyzed and the phosphate hydroxyl groups formed by the hydrolysis are neutralized.

[0022] As a further improvement, the vacuum devolatilization time in step 3) is 2-4 hours. During the vacuum devolatilization process, dry nitrogen is continuously introduced or the reaction system is stirred to remove residual small molecules.

[0023] Secondly, the present invention also provides an organosilicon phosphate surfactant prepared by the method.

[0024] This invention uses tris(trimethylsilyl)phosphate instead of phosphorus pentoxide, polyphosphoric acid, and phosphorus oxychloride. Under relatively mild conditions without the participation of strong protic acids and halogenated phosphorylating agents, the hydroxyl groups at the polyether end of the monohydroxyl-terminated polyether-modified siloxane undergo a substitution reaction with phosphorus atoms to form stable P-O-C bonds, reducing the hydrolysis and chain scission effects of acidic media on the siloxane backbone. By controlling the water content of the raw materials, the molar ratio of hydroxyl groups to tris(trimethylsilyl)phosphate, and the reaction temperature and time, the selectivity and structural uniformity of the phosphorylation reaction are improved. During the reaction, dry nitrogen is continuously introduced and trimethylsilanol, hexamethyldisiloxane, and trace amounts of water are collected by condensation, which helps to shift the reaction equilibrium towards the product direction and reduces the hydrolysis of siloxane segments caused by water accumulation. Subsequently, an aqueous organic base is used to hydrolyze and neutralize the residual P-O-Si(CH3)3 groups, which can form a phosphate salt structure with good hydrophilicity. Residual small molecules are removed by vacuum devolatilization. Therefore, this invention can achieve a hydroxyl conversion rate of not less than 92% while maintaining a number-average molecular weight retention rate of not less than 95% for siloxane segments. The resulting product has good water solubility, wettability, emulsification, electrolyte resistance, and storage stability. In addition, this method does not generate chlorine-containing corrosive gases or corresponding waste salts, reduces organic solvents, water washing, and extraction operations, and has the advantages of mild reaction conditions, easy process control, simplified post-processing, and suitability for industrial production. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the overall process flow of the present invention.

[0026] Figure 2 This is a schematic diagram of the reaction and byproduct condensation and collection device used in the embodiments of the present invention.

[0027] Figure 3 This is a schematic diagram of the reaction process of phosphorylation, trimethylsilanol condensation and controlled hydrolysis of residual silanyl phosphate in this invention.

[0028] Figure 4 This is a comparison chart of hydroxyl conversion rate and number-average molecular weight retention rate of siloxane segments for Examples 1-3 and Comparative Examples 1-5.

[0029] Figure 5 This is a comparison chart of the residual silicon-based phosphate ratios in Examples 1-3 and Comparative Examples 3-5.

[0030] Figure 6 The graph shows the changes in pH value and dynamic viscosity of Examples 1-3 and Comparative Examples 1-5 before and after storage at 54°C for 14 days.

[0031] Figure 7 The diagram shows a comparison of the emulsification stability of the products prepared in Examples 1-3 and Comparative Examples 1-5.

[0032] Figure 8 Product of Example 1 31 P{ 1 H} nuclear magnetic resonance spectrum.

[0033] In the diagram: 1. Reactor; 2. Mechanical stirrer; 3. Temperature detection device; 4. Nitrogen source; 5. Gas dryer; 6. Nitrogen inlet pipe; 7. Condenser; 8. Receiver; 9. Vacuum device; 10. Dropping device; 11. Filter device. Detailed Implementation

[0034] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be noted that the following embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. Unless otherwise specified, all raw materials used are industrial grade or chemically pure, and all water used is deionized water.

[0035] I. General Description of Preparation Method

[0036] like Figure 1 As shown, the preparation method of the present invention mainly includes raw material dehydration, phosphorylation, simultaneous removal of by-products, controlled hydrolysis and neutralization, vacuum devolatilization, and filtration purification.

[0037] First, the hydroxyl-terminated polyether-modified siloxane was dehydrated under reduced pressure to ensure a moisture content of no more than 0.05% by mass. Then, under dry nitrogen protection, the hydroxyl-terminated polyether-modified siloxane was mixed with tris(trimethylsilyl)phosphate, allowing the terminal hydroxyl groups of the polyether to undergo a substitution reaction with the tris(trimethylsilyl)phosphate. During the reaction, dry nitrogen was continuously introduced, and the reaction tail gas was passed into a condenser to continuously remove the trimethylsilanol, hexamethyldisiloxane, and trace amounts of water produced from the reaction system.

[0038] After phosphorylation, the reactants are cooled, and an aqueous organic base is added to hydrolyze the remaining silanyl phosphate bonds that are not substituted by the terminal hydroxyl groups of the polyether, and to form at least some of the phosphate hydroxyl groups into organic amine salts. Finally, water, trimethylsilanol, and hexamethyldisiloxane, among other low-molecular-weight substances, are removed by vacuum devolatilization, and the product is cooled and filtered to obtain an organosilicon phosphate surfactant.

[0039] This invention sets up the phosphorylation stage under low moisture content conditions and the hydrolysis and neutralization stage under moist conditions in sequence, so as to avoid the hydrolysis of tris(trimethylsilyl) phosphate esters caused by moisture before the start of phosphorylation, while at the same time, it can convert the residual silyl phosphate ester structure into phosphate hydroxyl groups or phosphate salts after the reaction is completed.

[0040] II. Reaction Apparatus

[0041] like Figure 2 As shown, the reaction apparatus includes a reaction vessel 1, a mechanical stirrer 2, a temperature detection device 3, a nitrogen source 4, a gas dryer 5, a nitrogen inlet pipe 6, a condenser 7, a receiver 8, a vacuum device 9, a dropping device 10, and a filter device 11.

[0042] Mechanical stirrer 2 is installed on reactor 1 to ensure that the single-hydroxyl-terminated polyether modified siloxane and tris(trimethylsilyl)phosphate form a homogeneous reaction system. Temperature detection device 3 has its detection end inserted into the reactants to detect the actual material temperature.

[0043] Nitrogen source 4 is connected to nitrogen inlet pipe 6 via gas dryer 5. The outlet of nitrogen inlet pipe 6 is preferably located below the surface of the reaction liquid to ensure sufficient contact between the dried nitrogen and the reactants. Molecular sieves, color-changing silica gel, or other drying materials capable of removing moisture from the nitrogen can be installed inside the gas dryer 5.

[0044] The gas phase outlet of reactor 1 is connected to condenser 7, and the liquid phase outlet of condenser 7 is connected to receiver 8. During the phosphorylation process, nitrogen gas carries trimethylsilanol, hexamethyldisiloxane, and trace amounts of water out of reactor 1, which are then condensed by condenser 7 and enter receiver 8, thereby reducing the concentration of the above-mentioned low-molecular-weight substances in the reaction system.

[0045] Vacuum device 9 is connected to the gas phase outlet of reactor 1 and is used to depressurize and devolatilize the material after the reaction. Dropping device 10 is used to add tris(trimethylsilyl)phosphate or aqueous organic base. Filter device 11 is located at the discharge end of reactor 1 and is used to remove small amounts of mechanical impurities.

[0046] Figure 2 The apparatus shown is suitable for both laboratory glass reactors and industrial stainless steel reactors. During industrial scale-up, the nitrogen flow rate can be adjusted according to the reactor volume, liquid level, and gas-liquid contact efficiency; however, excessive nitrogen flow should be avoided to prevent material entrainment into the condenser.

[0047] III. Reaction Principle

[0048] like Figure 3 As shown, the reaction process of the present invention includes three interconnected reaction stages.

[0049] The first stage is the phosphorylation reaction. In the monohydroxyl-terminated polyether-modified siloxane, the terminal carbon hydroxyl group attacks the phosphorus atom in the tris(trimethylsilyl)phosphate, replacing the trimethylsiloxy group and forming a phosphorus-oxygen-carbon bond. This reaction can be represented as:

[0050] ;

[0051] In the formula, ROH represents a single-hydroxyl-terminated polyether modified siloxane containing a polyether-terminated carbon hydroxyl group.

[0052] The second stage is the trimethylsilanol condensation reaction. The trimethylsilanol generated by phosphorylation can undergo condensation to form hexamethyldisiloxane and water:

[0053] ;

[0054] pass Figure 2 The nitrogen inlet pipe 6, condenser 7, and receiver 8 shown can remove trimethylsilanol, hexamethyldisiloxane, and trace amounts of water while the reaction is in progress, thereby driving the first-stage reaction to continue.

[0055] The third stage is controlled hydrolysis and neutralization. After phosphorylation, an aqueous organic base is added, and the water hydrolyzes the remaining silicon-based phosphate bonds.

[0056] ;

[0057] The phosphate hydroxyl groups formed by hydrolysis then react with organic bases to form phosphate ester salts. Since water is added after the phosphate esterification is basically complete, it will not consume a large amount of tris(trimethylsilyl)phosphate in the initial reaction stage.

[0058] IV. Main Raw Materials

[0059] The tris(trimethylsilyl)phosphate used in the examples had a purity of 98.8% and a moisture content of 0.018% by mass.

[0060] The number average molecular weight of PEG-8 hydroxyl-terminated polyether modified trisiloxane is approximately 600 g / mol, and the hydroxyl value is 94.0 mg KOH / g; the number average molecular weight of hydroxyl-terminated polyether modified polydimethylsiloxane A is approximately 2000 g / mol, and the hydroxyl value is 28.0 mg KOH / g; the number average molecular weight of hydroxyl-terminated polyether modified polydimethylsiloxane B is approximately 1200 g / mol, and the hydroxyl value is 46.8 mg KOH / g.

[0061] The aforementioned single-hydroxyl-terminated polyether-modified siloxanes all contain only one hydroxyl group attached to the terminal carbon atom of the polyether chain, and do not contain silanol groups directly attached to silicon atoms. Before use, the raw materials are placed in a vacuum drying kettle and dehydrated for 2 hours at 90°C and -0.09 MPa.

[0062] The organic bases used in the examples include dimethylethanolamine, triethylamine, and triethanolamine, all with a purity of not less than 99.0%.

[0063] V. Preparation of tris(trimethylsilyl)phosphate

[0064] Add 98.0 g of anhydrous phosphoric acid to a 1 L reactor equipped with a stirrer, thermometer, condenser, and tail gas absorption device, and heat to 60 °C under dry nitrogen protection. Weigh 260.8 g of hexamethyldisilazane with a purity of 99.0% and slowly add it dropwise to the reactor over 2 hours.

[0065] The feed amount of hexamethyldisilazane was 1.60 mol, equivalent to 3.20 mol of trimethylsilyl equivalent. The ammonia gas generated during the dropwise addition was condensed and then introduced into the dilute sulfuric acid absorption solution.

[0066] After the addition was complete, the reaction system was heated to 100℃ and reacted at a constant temperature for 4 hours. After the reaction was completed, vacuum distillation was carried out under a vacuum of -0.095 MPa, with the reactor temperature controlled at 115–125℃, to remove unreacted hexamethyldisilazane and low-boiling-point impurities, yielding 298.6 g of colorless and transparent liquid.

[0067] The obtained tris(trimethylsilyl)phosphate had a purity of 98.8%, a moisture content of 0.018% by mass, and a separation yield of 95.0%. The product was stored in a sealed container at 5–10°C under dry nitrogen protection.

[0068] Its reaction can be represented as:

[0069] ;

[0070] It should be noted that the theoretical molar ratio of hexamethyldisilazane to anhydrous phosphoric acid is 1.5:1; the 3.20:1 ratio is the ratio of trimethylsilyl equivalent to anhydrous phosphoric acid, not the ratio of hexamethyldisilazane molecules to anhydrous phosphoric acid.

[0071] VI. Testing Methods

[0072] 1. Hydroxyl conversion rate

[0073] Quantitative proton nuclear magnetic resonance (NMR) was used for determination. The residual hydroxyl content was expressed as the normalized integral ratio of the characteristic peak of the terminal hydroxymethyl group in the polyether to that of the characteristic peak of the silylic methyl group. The hydroxyl conversion rate was calculated using the following formula:

[0074] ;

[0075] In the formula, Hydroxyl conversion rate; The normalized integral value of the end-hydroxymethyl characteristic peak of the polyether relative to the silanyl characteristic peak before the reaction; This is the normalized integral value of the residual polyether terminal hydroxymethyl characteristic peak relative to the silanyl characteristic peak after the reaction.

[0076] 2. Number-average molecular weight retention

[0077] The determination was performed using gel permeation chromatography. The mobile phase was tetrahydrofuran, the flow rate was 1.0 mL / min, the column temperature was 35 °C, and the detector was a differential refractive index detector.

[0078] The product was acidified, desalted, and vacuum dried before analysis, and the mass of the theoretically introduced phosphate groups was deducted based on the hydroxyl conversion rate. The number-average molecular weight retention was calculated using the following formula:

[0079] ;

[0080] In the formula, The number-average molecular weight retention rate of siloxane segments; The number-average molecular weight of the desalted product; Net mass of phosphate ester groups introduced, calculated based on hydroxyl conversion rate; This represents the number-average molecular weight of the starting materials before the reaction.

[0081] 3. Residual silicon-based phosphate ratio

[0082] The quantitative phosphorus nuclear magnetic resonance method was used for determination, and the result was calculated according to the following formula:

[0083] ;

[0084] In the formula, The percentage of residual silicon-based phosphate esters; The peak area corresponding to the residual silicon-based phosphate ester; This represents the sum of the peak areas of all phosphorus species.

[0085] 4. Other performance tests

[0086] The pH value of the product was determined by a 10% by mass aqueous solution at 25°C; the dynamic viscosity was determined by a rotational viscometer at 25°C; the color was determined by the platinum-cobalt colorimetric method; and the surface tension was determined by the platinum ring method for the equilibrium surface tension of a 0.1% by mass aqueous solution of the product at 25°C.

[0087] The thermal storage stability test was conducted by sealing the sample and storing it in a 54°C constant temperature chamber for 14 days. The pH value, dynamic viscosity, and surface tension before and after storage were measured, and the presence of stratification, precipitation, or gelation was observed.

[0088] The emulsification stability test was conducted by mixing 10g of dimethyl silicone oil, 1g of the test sample and 89g of deionized water, shearing at 10000r / min for 3min, and allowing it to stand at room temperature for 24h and 7d, and recording the volume of the precipitated water layer.

[0089] VII. Examples and Comparative Examples

[0090] Example 1

[0091] according to Figure 1 The process shown and Figure 2 The apparatus shown is used to clean, dry, and purge a 2L glass reactor with nitrogen.

[0092] 720g of PEG-8 single-hydroxyl-terminated polyether modified trisiloxane was weighed and added to reactor 1. After dehydration, the moisture content of the raw material was 0.032% by mass. Based on the hydroxyl value, the raw material contained 1.206 mol of hydroxyl groups.

[0093] Under the stirring of mechanical stirrer 2 and the protection of drying nitrogen, the raw material is heated to 50°C, and 310g of tris(trimethylsilyl)phosphate with a purity of 98.8% is added dropwise over 30 minutes through dropwise addition device 10. The effective amount of tris(trimethylsilyl)phosphate is 0.975mol, and the molar ratio of hydroxyl groups to tris(trimethylsilyl)phosphate is 1.24:1.

[0094] After the feed is completed, the reaction system is heated to 60℃ and reacted for 4 hours. During the reaction, nitrogen from nitrogen source 4 is dried by gas dryer 5 and then introduced into reactor 1 from below the liquid level through nitrogen inlet pipe 6. The reaction tail gas is condensed by condenser 7 and then enters receiver 8. A total of 91.4g of condensate is collected during the reaction.

[0095] After the reaction was complete, the temperature was lowered to 30°C. 35.0 g of deionized water and 126.5 g of dimethylethanolamine were mixed and added dropwise to reactor 1 over 60 min using a dropping device 10. The highest material temperature during the dropping process was 36.2°C. After the dropping was completed, stirring was continued for 4 h. The pH of the resulting 10% (w / w) aqueous solution was 6.98.

[0096] The material was then heated to 110°C, and the pressure in the reactor was adjusted to -0.09 MPa using vacuum device 9, followed by depressurization and devolatilization for 3 hours. After cooling to 45°C, the material was filtered through filter device 11 to obtain an organosilicon phosphate surfactant.

[0097] like Figure 8 As shown, using 31 P{ 1 The phosphorus-containing components of the product from Example 1 were characterized by ¹H NMR spectroscopy. D₂O was used as the solvent, 85% phosphoric acid as the external standard, and the test temperature was 25°C. 31 The P-resonance frequency is 161.98 MHz, using an inverse-gated proton decoupling method, with a relaxation delay of 10 s and 128 scans. Example 1 product in δ... 3.62 A phosphate monoester signal was observed nearby, at δ 0.12 A phosphate diester signal was observed nearby, at δ 5.78 A small amount of inorganic phosphorus component signal was observed nearby. The integration results showed that the relative integrated areas of phosphate monoester, phosphate diester, and inorganic phosphorus component were 82.6%, 16.6%, and 0.8%, respectively.

[0098] Example 1 was performed in three parallel batches. The average hydroxyl conversion rate was 94.1%, the average number-average molecular weight retention rate was 97.9%, the average residual silanized phosphate ratio was 0.8%, the color was 150 Hazen, the dynamic viscosity at 25°C was 69 mPa·s, and the surface tension was 20.9 mN / m.

[0099] Example 2

[0100] according to Figure 2 The apparatus shown was used to clean, dry, and purge a 5L reactor with nitrogen. 2600g of hydroxyl-terminated polyether-modified polydimethylsiloxane A was weighed and added to reactor 1. After dehydration, the moisture content of the raw material was 0.028% by mass, and the raw material contained 1.298 mol of hydroxyl groups.

[0101] Under stirring and nitrogen protection, the raw material was heated to 60°C, and 318g of tris(trimethylsilyl)phosphate with a purity of 98.8% was added dropwise over 40 minutes. The effective amount of the substance was 0.999mol, and the molar ratio of hydroxyl groups to tris(trimethylsilyl)phosphate was 1.30:1.

[0102] After feeding, the temperature was raised to 80℃ and the reaction was carried out for 4 hours. Dry nitrogen gas was continuously introduced during the reaction. The reaction tail gas was condensed by condenser 7 and then entered receiver 8. A total of 96.8g of condensate was collected.

[0103] After the reaction was complete, the temperature was lowered to 30°C. 35.0 g of deionized water and 146.0 g of triethylamine were added to the reactor in batches, controlling the material temperature to not exceed 40°C. After the addition was complete, stirring was continued for 4 hours. The pH of the 10% by mass aqueous solution of the product was 7.02.

[0104] Subsequently, the surfactant was subjected to devaporization under reduced pressure at 115℃ and -0.095MPa for 3 hours, followed by cooling and filtration to obtain an organosilicon phosphate surfactant.

[0105] The average hydroxyl conversion rate of the three parallel batches was 93.6%, the average number-average molecular weight retention rate was 96.8%, the average residual silica-based phosphate ratio was 0.9%, the color was 40 Hazen, the dynamic viscosity at 25°C was 351 mPa·s, and the surface tension was 24.9 mN / m.

[0106] Example 3

[0107] Weigh 1200g of hydroxyl-terminated polyether-modified polydimethylsiloxane B and add it to a 3L reactor that has been dried and purged with nitrogen. After dehydration, the moisture content of the raw material is 0.035% by mass, and the raw material contains 1.001mol of hydroxyl groups.

[0108] The raw material was heated to 50°C under stirring and nitrogen protection, and 255g of tris(trimethylsilyl)phosphate with a purity of 98.8% was added dropwise over 30 minutes. The amount of effective substance was 0.801mol, and the molar ratio of hydroxyl groups to tris(trimethylsilyl)phosphate was 1.25:1.

[0109] After feeding, the reaction was carried out at 70°C for 3 hours. Dry nitrogen gas was continuously introduced during the reaction, and a total of 74.6 g of condensate was collected.

[0110] After the reaction was complete, the temperature was lowered to 30°C. 28.5 g of deionized water and 173.0 g of triethanolamine were mixed and slowly added to the reactor, with the temperature controlled not to exceed 40°C. After the addition was complete, stirring was continued for 3 hours. The pH of the resulting 10% (by mass) aqueous solution was 6.95.

[0111] Subsequently, the surfactant was de-idhopped under reduced pressure at 110℃ and -0.09MPa for 3 hours, and then cooled and filtered to obtain an organosilicon phosphate surfactant.

[0112] The average hydroxyl conversion rate of the three parallel batches was 95.0%, the average number-average molecular weight retention rate was 97.4%, the average residual silica-based phosphate ratio was 0.7%, the color was 52 Hazen, the dynamic viscosity at 25°C was 184 mPa·s, and the surface tension was 22.7 mN / m.

[0113] Comparative Example 1

[0114] The same batch of PEG-8 single-hydroxyl-terminated polyether modified trisiloxane as in Example 1 was used, with phosphorus pentoxide replacing tris(trimethylsilyl)phosphate in an equal molar amount of phosphorus. 720g of raw material was added to the reactor, and phosphorus pentoxide was added in batches over 2 hours under nitrogen protection and stirring. Local agglomeration and significant exothermic reactions occurred during the addition process, with the highest material temperature reaching 118°C. After addition, the reaction was carried out at 100°C for 3 hours, followed by neutralization with dimethylethanolamine, and then vacuum devolatilization and filtration. The average hydroxyl conversion rate of the three parallel batches was 85.6%, the average number-average molecular weight retention was 86.9%, the average color of the product was 186 Hazen, and the surface tension was 27.6 mN / m.

[0115] Comparative Example 2

[0116] The same batch of single-hydroxyl-terminated polyether-modified polydimethylsiloxane A as in Example 2 was used, with polyphosphoric acid used instead of tris(trimethylsilyl)phosphate in an equal molar amount of phosphorus. The reactants were reacted at 100°C for 4 hours, and the water generated in the reaction was removed under -0.08 MPa. The viscosity of the material increased significantly in the later stage of the reaction. After the reaction, the mixture was neutralized with triethylamine, followed by vacuum devolatilization and filtration. The average hydroxyl conversion rate of the three parallel batches was 89.3%, the average number-average molecular weight retention was 90.8%, the average color of the product was 113 Hazen, and the surface tension was 26.9 mN / m.

[0117] Comparative Example 3

[0118] Except that nitrogen was not introduced during the phosphate esterification process and the reaction tail gas was not introduced into condenser 7 and receiver 8, the other conditions were the same as in Example 1. The average hydroxyl conversion rate of the three parallel batches was 88.7%, the average number-average molecular weight retention rate was 94.0%, the residual silanized phosphate ratio was 2.8%, and the surface tension was 24.7 mN / m. These results indicate that if no nitrogen gas is introduced during the phosphate esterification process, the reaction tail gas will be less likely to be successfully phosphated. Figure 2 The nitrogen purging and condensation collection structure shown indicates that low-molecular-weight byproducts accumulate in the reaction system, preventing the phosphorylation reaction from proceeding fully towards the product.

[0119] Comparative Example 4

[0120] The phosphoesterification reaction was carried out according to Example 1. After the reaction, no deionized water was added; only anhydrous dimethylethanolamine was added to adjust the initial pH, followed by direct vacuum devolatilization. The average hydroxyl conversion rate of the three parallel batches was 94.0%, and the average number-average molecular weight retention rate was 97.7%, but the proportion of residual silanized phosphate was 14.6%. The initial pH of the product was 7.03, which decreased to 5.82 after storage at 54°C for 14 days, and slight turbidity appeared. This result indicates that anhydrous organic bases cannot fully hydrolyze the residual silanized phosphate structure. Figure 3 The controlled hydrolysis step shown plays an important role in reducing the proportion of residual silanol phosphates and maintaining pH stability during storage.

[0121] Comparative Example 5

[0122] Except for adjusting the initial moisture content of the PEG-8 single-hydroxyl-terminated polyether-modified trisiloxane to 0.10% by mass, the other conditions were the same as in Example 1. The average hydroxyl conversion rate of the three parallel batches was 90.1%, the average number-average molecular weight retention was 91.7%, the residual silanyl phosphate ratio was 4.9%, the average color of the product was 96 Hazen, and the surface tension was 25.8 mN / m. These results indicate that excessive moisture in the raw material before the start of phosphate esterification will cause premature hydrolysis of tris(trimethylsilyl)phosphate and the formation of acidic phosphorus species that can promote the hydrolysis of siloxane segments.

[0123] VIII. Structural and Transformation Effect Analysis

[0124] The main detection results of the examples and comparative examples are shown in Table 1.

[0125] Table 1. Structural and performance test results of the embodiments and comparative examples.

[0126]

[0127] Figure 4 The graph was plotted based on the hydroxyl conversion rate and number-average molecular weight retention rate in Table 1. Figure 4 As shown, the hydroxyl conversion rate of Examples 1-3 is not less than 92%, and the number average molecular weight retention rate is not less than 95%. The phosphorus pentoxide method, the polyphosphoric acid method, the comparative examples that do not remove byproducts, and the raw material with excessive moisture content cannot simultaneously achieve the above two indicators.

[0128] Among them, the number-average molecular weight retention rates of Comparative Examples 1 and 2 were significantly reduced, indicating that the strong acidic phosphorus source would have an adverse effect on the siloxane segments; the hydroxyl conversion rate of Comparative Example 3 was lower than that of Example 1, indicating that the simultaneous removal of low-molecular-weight byproducts could promote the phosphorylation reaction; Comparative Example 5 showed a decrease in both hydroxyl conversion rate and number-average molecular weight retention rate, indicating that the control of raw material moisture and the protection of drying nitrogen have a synergistic effect.

[0129] like Figure 5 As shown, the residual silicon-based phosphate ester ratios in Examples 1-3 were 0.7%-0.9%, while the ratio in Comparative Example 4, which did not undergo controlled hydrolysis, reached 14.6%. This result indicates that simply adding anhydrous organic bases cannot fully convert the residual silicon-based phosphate ester structure; controlled addition of water and organic bases is a crucial step in ensuring the stability of the final product structure.

[0130] IX. Stability Analysis of Thermal Storage

[0131] The test results of the examples and comparative examples stored at 54°C for 14 days are shown in Table 2.

[0132] Table 2 Results of thermal storage stability test

[0133]

[0134] Figure 6 The plot was drawn based on the pH and dynamic viscosity data in Table 2. Figure 6 As shown, in Examples 1-3, the pH value change before and after heat storage was no greater than 0.07, the dynamic viscosity change rate was no greater than 3%, and no stratification, precipitation or gelation occurred.

[0135] The pH value of Comparative Example 4 decreased from 7.03 to 5.82 after thermal storage, indicating that the residual siloxane phosphate structure continued to hydrolyze and release acidic groups during storage. The dynamic viscosity of Comparative Examples 1, 2, and 5 increased significantly, indicating that a strongly acidic reaction environment or excessively high initial moisture content can lead to further condensation or association of siloxane segments after breakage.

[0136] 10. Emulsion Stability Analysis

[0137] Emulsion stability tests were conducted using the same ratio of dimethyl silicone oil, water, and surfactant, and the results are shown in Table 3.

[0138] Table 3 Results of emulsification stability test

[0139]

[0140] like Figure 7 As shown, the water content after standing for 7 days in Examples 1-3 was no more than 1.2 mL, significantly lower than that in the comparative examples. The better emulsification stability of the products in these examples corresponds to their higher hydroxyl conversion rate, lower residual silanol phosphate ratio, and better retention of siloxane segments.

[0141] XI. Comprehensive Analysis

[0142] Combination Figure 4It can be seen that simply replacing the traditional phosphorylating agent with tris(trimethylsilyl)phosphate does not necessarily achieve the technical effect of this invention. Comparative Example 3 used the same phosphorylating agent, but did not remove byproducts during the reaction process; its hydroxyl conversion rate and number-average molecular weight retention rate were both lower than the limits set by this invention.

[0143] Combination Figure 5 It can be seen that adding anhydrous organic base directly after phosphoesterification will not significantly reduce the hydroxyl conversion rate and number-average molecular weight retention rate, but it will retain a high proportion of silicon-based phosphate ester structure, which will cause changes in pH and viscosity during storage.

[0144] Combination Figure 6 and Figure 7 It can be seen that the low moisture content raw material control, dry nitrogen protection, simultaneous condensation and removal of by-products, and subsequent controlled hydrolysis and neutralization of the present invention work together to enable the product to have a high phosphorylation conversion rate, a good degree of siloxane chain segment retention, a low residual silicon-based phosphate ratio, and good thermal storage and emulsification stability.

[0145] Therefore, this invention is not a simple parallel of known phosphorylation reagents and conventional post-treatment conditions, but rather a synergistic control of the time when water enters the reaction system, the removal of low-molecular-weight byproducts, and the conversion of residual silicon-based phosphate esters, so that the hydroxyl conversion rate of the obtained organosilicon phosphate ester surfactant is not less than 92%, the number-average molecular weight retention rate of siloxane segments is not less than 95%, and it remains stable after being stored at 54°C for 14 days.

Claims

1. A process for the preparation of organosilicon phosphate surfactants by the trimethylsilyl phosphate method, characterized in that, Includes the following steps: 1) A hydroxyl-terminated polyether-modified siloxane is mixed with tris(trimethylsilyl)phosphate, such that the molar ratio of the hydroxyl groups in the hydroxyl-terminated polyether-modified siloxane to the tris(trimethylsilyl)phosphate is 1.2–1.3:

1. The mixture is reacted at 60–80°C for 2–4 hours under dry nitrogen protection. Dry nitrogen is continuously introduced during the reaction, and the reaction tail gas is collected by condensation to continuously remove the trimethylsilanol generated in the reaction, the hexamethyldisiloxane generated by the condensation of trimethylsilanol, and the water generated by the condensation. The hydroxyl-terminated polyether-modified siloxane contains one polyether-terminal carbon hydroxyl group and does not contain any silanol groups. 2) Cool the reactants obtained in step 1) to 10-40°C, add an aqueous organic base, hydrolyze the P-O-Si(CH3)3 groups that are not substituted by the terminal carbon hydroxyl groups of the polyether to form phosphate hydroxyl groups, and make at least some of the phosphate hydroxyl groups form phosphate ester salts with the organic base, and adjust the pH of the 10w% aqueous solution of the obtained product at 25°C to 6.5-7.

5. 3) The reactants obtained in step 2) are heated to 100-120°C for vacuum devolatilization to remove water, trimethylsilanol and hexamethyldisiloxane, and then filtered to obtain the organosilicon phosphate surfactant.

2. The method according to claim 1, characterized in that, The single-hydroxyl-terminated polyether modified siloxane described in step 1) has a moisture content of no more than 0.05 w and provides tris(trimethylsilyl)phosphate with a purity of no less than 98.5 w%.

3. The method according to claim 1, characterized in that, The single-hydroxyl-terminated polyether modified siloxane mentioned in step 1) is selected from at least one of single-hydroxyl-terminated polyether modified trisiloxane and single-hydroxyl-terminated polyether modified polydimethylsiloxane.

4. The method according to claim 1, characterized in that, The number-average molecular weight of the single-hydroxyl-terminated polyether modified siloxane described in step 1) is 600–2000 g / mol, and the dynamic viscosity at 25°C is 20–1000 mPa·s.

5. The method according to claim 1, characterized in that, In step 1), no organic solvent or esterification catalyst is added to the reaction. Tris(trimethylsilyl)phosphate is directly dispersed or dissolved in the single-terminated hydroxyl polyether modified siloxane to form a homogeneous reaction system.

6. The method according to claim 1, characterized in that, Step 1) During the reaction, dry nitrogen gas is introduced from below the surface of the reaction liquid. The gas phase outlet of the reaction vessel is connected in sequence to a condenser and a receiving device to collect trimethylsilanol and hexamethyldisiloxane while the reaction is in progress.

7. The method according to claim 1, characterized in that, The organic base in the aqueous organic base is selected from at least one of triethanolamine, triethylamine, dimethylethanolamine, monoisopropanolamine, diisopropanolamine, and tert-butanolamine.

8. The method according to claim 1, characterized in that, Step 2) includes: adding the aqueous organic base dropwise at 10-40°C, and continuing to stir for 1-4 hours after the addition is complete, so that the residual P-O-Si(CH3)3 groups are hydrolyzed and the phosphate hydroxyl groups formed by the hydrolysis are neutralized.

9. The method according to claim 1, characterized in that, The vacuum devolatilization time in step 3) is 2-4 hours. During the vacuum devolatilization process, dry nitrogen gas is continuously introduced or the reaction system is stirred to remove residual small molecules.

10. The organosilicon phosphate surfactant prepared by the method of any one of claims 1-9.

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